Patent Application
20250223782
The present invention relates to a work machine equipped with a hydraulic actuator.
In a conventional work machine, various hydraulic actuators such as a traveling motor for making a vehicle body travel, a swing motor for making an upperstructure swing, hydraulic cylinders for raising and lowering a front working device, and the like are mounted.
In such a work machine, an operation of braking of a hydraulic actuator causes the vehicle body to vibrate due to an inertial force, which degrades a ride quality. For this problem, Patent Literature 1 discloses a technique of reducing an inertial force generated in braking of a hydraulic actuator to prevent degradation in a ride quality.
Patent Literature 1: WO2014/013877
On the other hand, the works that a work machine performs include such a work that uses a large inertial force generated in braking of a hydraulic actuator while forcing an operator to tolerate the degradation in a ride quality, such as a work of dropping mud in the bucket. However, in the technique of Patent Literature 1, the work of dropping mud in the bucket as described above cannot be performed due to a reduced inertial force.
The present invention has been made in view of the circumstances described above, and an object thereof is to provide a work machine capable of appropriately switching between prevention of the degradation in a ride quality caused by an inertial force generated in braking of a hydraulic actuator and a work using the inertial force.
In order to achieve the object described above, the present invention provides a work machine comprising: a prime mover; a hydraulic pump configured to pump a hydraulic oil upon being driven by the prime mover; a hydraulic actuator configured to operate upon being supplied with or discharging the hydraulic oil; a supply flow path for supplying the hydraulic oil pumped by the hydraulic pump to the hydraulic actuator; a return flow path for bringing the hydraulic oil discharged from the hydraulic actuator to a hydraulic oil tank; a directional control valve having a spool that moves between a supply and discharge position and a blocking position, the supply and discharge position being a position for opening the supply flow path and the return flow path to cause the hydraulic oil to be supplied to and discharged from the hydraulic actuator, and the blocking position being a position for blocking the supply flow path and the return flow path to stop the hydraulic oil to be supplied to and discharged from the hydraulic actuator; an operation device configured to be operated between an operation position corresponding to the supply and discharge position of the spool and a neutral position corresponding to the blocking position of the spool; and a controller configured to bring the spool closer to the supply and discharge position as the operation device approaches the operation position to increase a volume of the hydraulic oil to be supplied to and discharged from the hydraulic actuator, and bring the spool closer to the blocking position as the operation device approaches the neutral position to reduce the volume of the hydraulic oil to be supplied to and discharged from the hydraulic actuator, wherein in a case where the operation device has been operated from the operation position toward the neutral position, the controller is configured to: move the spool from the supply and discharge position toward the blocking position at a first speed that is slower than a reference speed in a case where an operation speed of the operation device is less than a quick operation threshold; and move the spool from the supply and discharge position toward the blocking position at a second speed that is faster than the first speed in a case where the operation speed is equal to or more than the quick operation threshold.
According to the present invention, it is possible to obtain a work machine capable of appropriately switching between prevention of the degradation in a ride quality caused by an inertial force generated when a hydraulic actuator is braked and a work using the inertial force. The problems, arrangements, and advantageous effects other than those described above will be clarified by explanation of the embodiments below.
An embodiment of a hydraulic excavator 1 (work machine) according to the present invention will be described with reference to the drawings. It should be noted that a specific example of the work machine is not limited to the hydraulic excavator 1, but may be a wheel loader, a crane, a dump truck, or the like. It should be also noted that, the front, rear, left, and right are mentioned herein based on the viewpoint of an operator who rides on to operate the hydraulic excavator 1 unless otherwise specified.
The upperstructure 3 is supported on the undercarriage 2 so as to be made swung by a swing motor 3a (see
The front working device 4 includes a boom 4a supported on the upperstructure 3 so as to raise and lay down, an arm 4b supported on the distal end of the boom 4a so as to be rotatable, a bucket 4c supported on the distal end of the arm 4b so as to be rotatable, boom cylinders 4d for driving the boom 4a, an arm cylinder 4e for driving the arm 4b, and a bucket cylinder 4f for driving the bucket 4c. The counterweight 6 is a heavy object having an arc shape as viewed from the above, which is provided to adjust the weight balance with the front working device 4.
Each of the traveling motor 2a, the swing motor 3a, the boom cylinders 4d, the arm cylinder 4e, and the bucket cylinder 4f is an example of a hydraulic actuator that operates upon being supplied with and discharging hydraulic oil. However, specific examples of the hydraulic actuators are not limited thereto. Hereinafter, these actuators may be collectively referred to as “hydraulic actuators 2a, 3a, 4d to 4f” and the like.
The cab 7 has an internal space allowing an operator who operates the hydraulic excavator 1 to ride therein. In the internal space of the cab 7, a seat on which the operator sits and an operation device to be operated by an operator who has sit on the seat are placed.
The operation device accepts an operation for operating the hydraulic excavator 1 from an operator. An operation which has been made to the operation device by the operator causes the undercarriage 2 to travel, the upperstructure 3 to swing, and the front working device 4 to work. Specific examples of the operation device include a lever, a steering wheel, an accelerator pedal, a brake pedal, a switch, and the like. As illustrated in
The traveling pedal accepts an operation for instructing to cause the traveling motor 2a to rotate from the operator. The swing lever 7a accepts an operation for instructing to cause the swing motor 3a to rotate from the operator. The boom lever 7b accepts an operation for instructing to cause the boom cylinders 4d to expand and contract from the operator. The arm lever 7c accepts an operation for instructing to cause the arm cylinder 4e to expand and contract from the operator. The bucket lever 7d accepts an operation for instructing to cause the bucket cylinder 4f to extend and contract from the operator. The levers 7a to 7d do not have to be provided independently, but first and second levers may be provided and set such that the front and rear direction of the first lever corresponds to the swing lever 7a, the left and right direction of the first lever corresponds to the boom lever 7b, the front and rear direction of the second lever corresponds to the arm lever 7c, and the left and right direction of the second lever corresponds to the bucket lever 7d.
The engine 10 is a prime mover that generates power for driving the hydraulic excavator 1. The hydraulic oil tank 12 stores the hydraulic oil therein. The main pump 13 is rotated by the power of the engine 10, and pumps the hydraulic oil stored in the hydraulic oil tank 12 to a hydraulic oil supply flow path L1. The pilot pump 14 is rotated by the power of the engine 10 also serving as the power source of the main pump 13, and pumps the hydraulic oil stored in the hydraulic oil tank 12 to a pilot supply flow path L3 as pilot pressure oil.
The hydraulic oil supply flow path L1 is a flow path for the hydraulic oil, which extends from the hydraulic oil tank 12 to the hydraulic actuators 3a, 4d to 4f via the main pump 13 and the directional control valves 15 to 18 (in
The hydraulic actuators 3a, 4d to 4f are connected to the hydraulic oil tank 12 through a hydraulic oil return flow path L2. The hydraulic oil return flow path L2 is a flow path extending from the hydraulic actuators 3a, 4d to 4f to the hydraulic oil tank 12 via the directional control valves 15 to 18. That is, the hydraulic oil return flow path L2 is a return flow path for bringing the hydraulic oil discharged from the hydraulic actuators 3a, 4d to 4f back to the hydraulic oil tank 12.
A pilot supply flow path L3 is a flow path for the pilot pressure oil, which extends from the hydraulic oil tank 12 to pilot ports 15a to 18b of the directional control valves 15 to 18 via the pilot pump 14, the pilot primary valve 19, and the pilot control valves 20a to 23b. That is, the pilot supply flow path L3 is a flow path for supplying the pilot pressure oil pumped by the pilot pump 14 to the pilot ports 15a to 18b.
The pilot ports 15a to 18b are connected to the hydraulic oil tank 12 through a pilot return flow path L4. The pilot return flow path L4 is a flow path extending from the pilot ports 15a to 18b to the hydraulic oil tank 12 via the pilot control valves 20a to 23b. That is, the pilot return flow path L4 is a flow path for bringing the pilot pressure oil discharged from the pilot ports 15a to 18b back to the hydraulic oil tank 12.
The directional control valves 15 to 18 are placed on the hydraulic oil supply flow path L1 and the hydraulic oil return flow path L2. The directional control valves 15 to 18 control the volume and direction of the hydraulic oil supplied to the hydraulic actuators 3a, 4d to 4f through the hydraulic oil supply flow path L1 and the volume of the hydraulic oil discharged from the hydraulic actuators 3a, 4d to 4f through the hydraulic oil return flow path L2.
More specifically, the directional control valve 15 controls the supply and discharge of the hydraulic oil to and from the swing motor 3a, the directional control valve 16 controls the supply and discharge of the hydraulic oil to and from the boom cylinders 4d, the directional control valve 17 controls the supply and discharge of the hydraulic oil to and from the arm cylinder 4e, and the directional control valve 18 controls the supply and discharge of the hydraulic oil to and from the bucket cylinder 4f. The directional control valves 15 to 18 have the structures which are common to each other, and thus, in the following, the directional control valve 18 will be described in detail.
The directional control valve 18 includes a spool that moves between a blocking position A, a dump position B, and a cloud position C. The blocking position A is a position for blocking the hydraulic oil supply flow path L1 and the hydraulic oil return flow path L2 to stop the supply and discharge of the hydraulic oil to and from the bucket cylinder 4f. The dump position B and the cloud position C are positions for opening the hydraulic oil supply flow path L1 and the hydraulic oil return flow path L2 to allow the hydraulic oil to be supplied to and discharged from the bucket cylinder 4f. The dump position B and the cloud position C are located opposite to each other across the blocking position A.
More specifically, the dump position B is a position for causing the hydraulic oil to be supplied to a rod chamber of the bucket cylinder 4f and to be discharged from a bottom chamber so as to make the bucket cylinder 4f contract. The cloud position C is a position for causing the hydraulic oil to be supplied to the bottom chamber of the bucket cylinder 4f and to be discharged from the rod chamber so as to make the bucket cylinder 4f extend. As the spool approaches the blocking position A, the volume of hydraulic oil supplied to and discharged from the bucket cylinder 4f decreases. On the other hand, as the spool approaches the dump position B or the cloud position C, the volume of hydraulic oil supplied to and discharged from the bucket cylinder 4f increases.
The spool of the directional control valve 18 is initially at the blocking position A. In the directional control valve 18, the pilot pressure oil is supplied to the pilot port 18a and discharged from the pilot port 18b, whereby the spool moves from the blocking position A toward the dump position B. Furthermore, in the directional control valve 18, the pilot pressure oil is supplied to the pilot port 18b and discharged from the pilot port 18a, whereby the spool moves from the blocking position A toward the cloud position C.
The pilot primary valve 19 is placed on the pilot supply flow path L3 at a position closer to the pilot pump 14 than the pilot control valves 20a to 23b. The pilot primary valve 19 controls the volume of pilot pressure oil supplied from the pilot pump 14 to the pilot control valves 20a to 23b. The pilot primary valve 19 is a directional solenoid valve that controls the volume of supply in accordance with the control by the controller 50.
The pilot control valves 20a to 23b are placed on the pilot supply flow path L3 and the pilot return flow path L4 at positions closer to the pilot ports 15a to 18b than the pilot primary valve 19. The pilot control valves 20a to 23b control the volume of hydraulic oil supplied to the pilot ports 15a to 18b through the pilot supply flow path L3 and the volume of hydraulic oil discharged from the pilot ports 15a to 18b through the pilot return flow path L4. The pilot control valves 20a to 23b are directional solenoid valves that control the volume of supply in accordance with the control by the controller 50. The pilot control valves 20a to 23b have the structures which are common to each other, and thus, in the following, the pilot control valves 23a, 23b will be described in detail.
The pilot control valve 23a is placed between the pilot port 18a and the pilot pump 14, and, between the pilot port 18a and the hydraulic oil tank 12. The pilot control valve 23a includes a spool that moves between a supply position D and a return flow position E. The supply position D is a position for supplying the pilot pressure oil pumped from the pilot pump 14 to the pilot port 18a. The return flow position E is a position for bringing the pilot pressure oil discharged from the pilot port 18a back to the hydraulic oil tank 12. The spool of the pilot control valve 23a is initially at the return flow position E. The spool approaches the supply position D from the return flow position E as a command current output from the controller 50 increases.
The pilot control valve 23b is placed between the pilot port 18b and the pilot pump 14, and, between the pilot port 18b and the hydraulic oil tank 12. The pilot control valve 23b includes a spool that moves between the supply position D and the return flow position E. The spool moves in accordance with the magnitude of the command current, whereby the pilot control valve 23b is switched to the supply position D or the return flow position E.
The pressure sensors 24a to 27b are placed between the pilot control valves 20a to 23b and the pilot ports 15a to 18b. The pressure sensors 24a to 27b detect the pressure of pilot pressure oil (hereinafter, referred to as “pilot pressure”) supplied from the pilot control valves 20a to 23b to the pilot ports 15a to 18b. Then, the pressure sensors 24a to 27b output pressure signals indicating the pilot pressure as detected to the controller 50.
In the hydraulic oil supply flow path LIA, a main relief valve 28 for bringing the hydraulic oil flowing through the hydraulic oil supply flow path L1 back to the hydraulic oil tank 12 is mounted in the case where the discharge pressure of the main pump 13 exceeds a predetermined pressure. In the pilot supply flow path L3, a pilot relief valve 29 for bringing the pilot pressure oil flowing through the pilot supply flow path L3 back to the hydraulic oil tank 12 is mounted in the case where the discharge pressure of the pilot pump 14 exceeds a predetermined pressure. Furthermore, between the directional control valve 15 and the swing motor 3a, swing relief valves 30a, 30b that open in the case where the driving pressure or braking pressure of the swing motor 3a exceeds a predetermined pressure to prevent the driving pressure or the braking pressure from excessively increasing are mounted.
As illustrated in
However, a specific configuration of the controller 50 is not limited thereto, but may be implemented with hardware such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like.
The controller 50 controls the operations of the whole of the hydraulic excavator 1. The controller 50 causes the engine 10, the main pump 13, and the pilot pump 14 to rotate based on operation signals output from the various levers 7a to 7d and pressure signals output from the pressure sensors 24a to 27b, and also causes the pilot primary valve 19 and the pilot control valves 20a to 23b to open or close (outputs command currents).
As illustrated in
The controller 50 calculates a target operation pressure of the pilot pressure oil to be supplied to the pilot ports 18a, 18b based on the operation amount of the bucket lever 7d (more specifically, a current output operation amount MOcur, which will be described later). More specifically, the controller 50 increases the target operation pressure for the pilot port 18a as the fallen amount of the bucket lever 7d toward the dump position increases. Furthermore, the controller 50 increases the target operation pressure of the pilot port 18b as the fallen amount of the bucket lever 7d toward the cloud position increases.
As illustrated in
A previous input operation amount MIpre is an operation amount indicated in an operation signal output from the bucket lever 7d in the previous flag setting processing and hydraulic control processing (that is, an actual operation amount). A previous output operation amount MOpre is an operation amount corrected in the previous hydraulic control processing (that is, an operation amount for a command current). A current input operation amount MIcur is an operation amount indicated in an operation signal output from the bucket lever 7d in the current flag setting processing and hydraulic control processing (that is, an actual operation amount). A current output operation amount MOcur is an operation amount corrected in the current hydraulic control processing (that is, an operation amount for a command current). The previous input operation amount MIpre and the previous output operation amount MOpre are stored in the memory 52.
As illustrated in
Then, in response to the previous output operation amount MOpre being less than the neutral output threshold THno (S12: Yes), the controller 50 sets “inactive (first value)” in a quick operation flag stored in the memory 52 (S13), and ends the flag setting processing. The previous output operation amount MOpre being less than the neutral output threshold THno refers to the case that the bucket lever 7d has been pulled back in vicinity of the neutral position (in other words, the spool of the directional control valve 18 has moved near the blocking position A). The quick operation flag is a flag indicating that the bucket lever 7d has been quickly operated toward the neutral position. The “inactive” is indicative of the case that the bucket lever 7d has not been quickly operated toward the neutral position.
On the other hand, in response to the previous output operation amount MOpre being equal to or more than the neutral output threshold THno (S12: No), the controller 50 compares an input operation variation amount ΔMI with a quick operation threshold THr stored in the memory 52 (S14). The input operation variation amount ΔMI is the amount of change expressed with a difference of the current input operation amount MIcur relative to the previous input operation amount MIpre (MIpre−Micur), or is the ratio of the current input operation amount MIcur relative to the previous input operation amount MIpre (MIcur/MIpre). The quick operation threshold THr is a threshold relating to the speed of an operation (referred to as an “operation speed” herein) expressed as the amount of change in an operation per unit time, and is set to a value allowing the bucket lever 7d to be evaluated as having been quickly operated toward the neutral position (for example, the value set based on the difference of the current input operation amount MIcur relative to the previous input operation amount MIpre or the ratio of the current input operation amount MIcur relative to the previous input operation amount MIpre is 10% to 50% or the like).
In response to the input operation variation amount ΔMI being equal to or more than the quick operation threshold THr (S14: Yes), the controller 50 sets “active (second value)” in the quick operation flag (S15), and ends the flag setting processing. “Active” is indicative of the case that the bucket lever 7d has been quickly operated toward the neutral position. On the other hand, in response to the input operation variation amount ΔMI being less than the quick operation threshold THr (S14: No), the controller 50 ends the flag setting processing without changing the value of the quick operation flag.
Next, as illustrated in
The input and output difference ΔMIO is the amount of variation of the previous output operation amount MOpre relative to the current input operation amount MIcur (MIcur−MOpre or MOpre/MIcur). The first limit threshold TH1 and the second limit threshold TH2 are set to values allowing the previous output operation amount MOpre to be evaluated as having reached the current input operation amount MIcur (for example, 0% to 5%). The first limit threshold TH1 and the second limit threshold TH2 may be the same values or different values.
In response to the input and output difference ΔMIO being less than the first limit threshold TH1 (S22: Yes), the controller 50 sets the current output operation amount MOcur to a value which is the same as the current input operation amount MIcur (S24). That is, in the case where the bucket lever 7d has not been quickly operated toward the neutral position (S21: Yes) and also the previous output operation amount MOpre has reached the current input operation amount MIcur (S22: Yes), the controller 50 sets the current input operation amount MIcur to the current output operation amount MOcur without correcting the current input operation amount MIcur (S24).
In response to the input and output difference ΔMIO being equal to or more than the first limit threshold TH1 (S22: No), the controller 50 corrects the previous output operation amount MOpre with a first correction value VAL1 (for example, MOpre-VAL1) and sets it to the current output operation amount MOcur (S25). That is, in the case where the bucket lever 7d has not been quickly operated toward the neutral position (S21: Yes) and also the previous output operation amount MOpre has not reached the current input operation amount MIcur (S22: No), the controller 50 subtracts the first correction value VAL1 from the previous output operation amount MOpre and sets it to the current output operation amount MOcur regardless of the value of the current input operation amount MIcur (S25).
In response to the input and output difference ΔMIO being less than the second limit threshold TH2 (S23: No), the controller 50 sets the current output operation amount MOcur to a value which is the same as the current input operation amount MIcur (S24). That is, in the case where the bucket lever 7d has been quickly operated toward the neutral position (S21: No) and also the previous output operation amount MOpre has reached the current input operation amount MIcur (S23: No), the controller 50 sets the current input operation amount MIcur to the current output operation amount MOcur without correcting the current input operation amount MIcur (S24).
In response to the input and output difference ΔMIO being equal to or more than the second limit threshold TH2 (S23: Yes), the controller 50 corrects the previous output operation amount MOpre with a second correction value VAL2 (for example, MOpre−VAL2) and sets it to the current output operation amount MOcur (S26). That is, in the case where the bucket lever 7d has been quickly operated toward the neutral position (S21: No) and also the previous output operation amount MOpre has not reached the current input operation amount MIcur (S23: Yes), the controller 50 subtracts the second correction value VAL2 from the previous output operation amount MOpre and sets it to the current output operation amount MOcur regardless of the value of the current input operation amount MIcur (S26).
Next, the controller 50 calculates a target operation pressure for the current output operation amount MOcur set in steps S24 to S26 (S27). Subsequently, the controller 50 identifies a target current for the target operation pressure calculated in step S27, based on the correlation illustrated
The second correction value VAL2 is set to a value which is greater than the first correction value VAL1. That is, the difference between the previous output operation amount MOpre and the current output operation amount MOcur in step S25 is smaller than the difference between the previous output operation amount MOpre and the current output operation amount MOcur in step S26. Accordingly, the speed of movement of the spool of the directional control valve 18 based on the current output operation amount MOcur set in step S25 is slower than that of the spool of the directional control valve 18 based on the current output operation amount MOcur set in step S26. As a result, the braking of the bucket cylinder 4f in the case where the process in step S25 has been executed is limited more than that in the case where the process in step S26 has been executed.
Referring to
A period P1 illustrated in
A period P2 illustrated in
As described above, in the periods P1 and P2, a value which is the same as the current input operation amount MIcur is set to the current output operation amount MOcur, whereby the spool of the directional control valve 18 moves from the blocking position A toward the dump position B (the bucket cylinder 4f contracts) at the speed following the speed of an actual operation of the bucket lever 7d (the amount of an operation per unit time).
A period P3 illustrated in
A period P4 illustrated in
A period P5 illustrated in
In the periods P3 to P4 illustrated in
On the other hand, in
In the flag setting processing and the hydraulic control processing during the period P3-2 of
The variation in speed (decrease in speed) of the current output operation amount MOcur in the period P3-2 of
In the period P3 of
According to the embodiment described above, for example, the following advantageous effects can be obtained.
According to the embodiment described above, in the case where the speed of an operation for the bucket lever 7d toward the neutral position is less than the quick operation threshold THr, the spool of the directional control valve 18 is made moved at the first speed which is slower than the reference speed. This enables prevention of the degradation in a ride quality caused by an inertial force generated in braking of the bucket cylinder 4f.
On the other hand, according to the embodiment described above, in the case where the speed of an operation for the bucket lever 7d toward the neutral position is equal to or more than the quick operation threshold THr, the spool of the directional control valve 18 is made moved at the second speed which is slower than the reference speed and faster than the first speed. This enables an operation using an inertial force generated in braking of the bucket cylinder 4f (for example, a work of dropping mud) to be performed.
As described above, according to the embodiment described above, adjusting the speed in operating the bucket lever 7d toward the neutral position enables appropriate switching between prevention of the degradation in a ride quality caused by an inertial force and a work using the inertial force.
In the embodiment described above, the example in which the second speed is set slower than the reference speed has been described, however, the second speed may be set to a value which is the same as the reference speed. That is, the process of step S26 may be replaced with that of step S24. This enables use of a larger inertial force in the work of dropping mud or the like.
Next, referring to
As illustrated in
In combination of the flag setting processing of
In the flag setting processing and the hydraulic control processing during the period P3-3 of
In the flag setting processing and the hydraulic control processing in the period P3-4 of
According to the first modification, in the case where the speed of an operation for the bucket lever 7d being equal to or more than the quick operation threshold THr, the spool of the directional control valve 18 is made moved at the first speed if the previous output operation amount MOpre is less than the initial operation threshold THi (period P3-3 in
This makes the state in which the spool of the directional control valve 18 moves at the first speed (periods P3-1 and P3-3 in
Next, referring to
The controller 50 according to the second modification compares the input operation variation amount ΔMI with a stop threshold THs stored in the memory 52 (S16) in response to the input operation variation amount ΔMI being less than the quick operation threshold THr (S14: No). The stop threshold THs is set to a value allowing the bucket lever 7d to be estimated as being stopped (for example, 0% to 2%). That is, in step S16, the controller 50 determines whether the bucket lever 7d being operated from the target position toward the neutral position has been stopped halfway, or whether an input operation for the bucket lever 7d has turned from decreasing to increasing.
Next, in response to the input operation variation amount ΔMI being less than the quick operation threshold THr and also equal to or more than the stop threshold THs (S14: No & S16: Yes), the controller 50 ends the flag setting processing without changing the value of the quick operation flag. On the other hand, in response to the input operation variation amount ΔMI being less than the stop threshold THs (S16: No), the controller 50 compares the current input operation amount MIcur with a neutral input threshold THni stored in the memory 52 (S17). The neutral input threshold THni is set to a value allowing the bucket lever 7d to be evaluated as being brought back to the neutral position (for example, 0% to 2%). That is, the controller 50 determines whether the bucket lever 7d has returned to the neutral position in step S17.
Next, in response to the current input operation amount MIcur being equal to or more than the neutral input threshold THni (S17: Yes), the controller 50 sets “inactive (second value)” in the quick operation flag (S18), and ends the flag setting processing. On the other hand, in response to the current input operation amount MIcur being less than the neutral input threshold THni (S17: No), the controller 50 ends the flag setting processing without changing the value of the quick operation flag.
In combination of the flag setting processing of
In the flag setting processing and the hydraulic control processing during the period P6 of
In the flag setting processing and the hydraulic control processing during the period P7 of
According to the second modification, “inactive” is set in the quick operation flag at the timing in which the bucket lever 7d quickly operated toward the neutral position has been temporarily stopped (period P6), and thus, thereafter, in the case where the bucket lever 7d is slowly operated toward the neutral position, the braking of the bucket cylinder 4f can be greatly limited. This results in prevention of the degradation in a ride quality caused by an inertial force generated in braking of the bucket cylinder 4f.
Next, referring to
As illustrated in
Next, referring to
As illustrated in
According to the fourth modification, the processing according to the embodiment described above and the first to third modifications can be implemented with the drive circuit that is configured simply.
An engine has been exemplified as a prime mover so far, however, the prime mover is not limited thereto, but may be an electric motor, a fuel cell, or the like. Alternatively, a combination of these may be used as a prime mover.
The embodiment described above has been described as one of the examples of the present invention, and it is not intended that the scope of the present invention is limited to the embodiment described above. Those skilled in the art could implement the present invention in various other ways without making them depart from the concept of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-058663 | Mar 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/009308 | 3/10/2023 | WO |
