JP7496910B1 - Hydraulic control systems for construction machinery - Google Patents

Abstract

A hydraulic control system for a construction machine is provided that can prevent erroneous detection of the occurrence of traveling jerkiness when a traveling operation pedal is operated, and can obtain good traveling operability.
[Solution] The controller calculates a target operating pressure corresponding to the amount of operation of the traveling operation lever and the traveling operation pedal based on the operation signal of the traveling operation device, inputs the control operating pressure generated by the traveling electromagnetic proportional control valve detected by a pressure sensor, calculates the pressure difference between the target operating pressure and the control operating pressure, and determines whether traveling jerkiness has occurred based on the change in the pressure difference.
[Selected Figure] Figure 6

Description

The present invention relates to a hydraulic control system for construction machinery, and in particular to a hydraulic control system for construction machinery that can suppress the occurrence of the jerky phenomenon while traveling.

In construction machinery such as crawler cranes and hydraulic excavators, the vehicle body can vibrate due to the road surface while the operator is driving by operating the driving control device, causing driving jerkiness. Driving jerkiness occurs when the vehicle body vibrates due to the road surface, causing the operator's posture to become unstable, and the operator's shaking is transmitted to the control lever or pedal being operated, causing the control lever or pedal to shake in a different phase from the vehicle body vibration, causing the vehicle body to unintentionally accelerate or decelerate.

Various methods have been proposed to effectively suppress the occurrence of such traveling jerky, one example of which is Patent Document 1.

Patent Document 1 proposes using an inertial sensor to detect vibrations of the upper rotating body or the seats in the driver's cab, and if the acceleration of the upper rotating body or the seats in the forward and backward directions increases and decreases a predetermined number of times or more, or if an operating pressure sensor detects the driving command value of the driving operation device and the increase and decrease of the driving command value is repeated a predetermined number of times or more, it is determined that a predetermined condition is met and the driving operation is unstable (driving jerkiness is occurring), and the driving command value is corrected to suppress fluctuations in the driving command value.

Publication No. WO2021/025035

Patent Document 1 uses an inertial sensor to detect the vibration of the upper rotating body or the seat and the driving command value, and detects the occurrence of driving jerkiness by determining whether the increase/decrease in the vibration acceleration of the upper rotating body or the seat or the increase/decrease in the driving command value has been repeated a predetermined number of times or more. However, if the occurrence of driving jerkiness is determined based on the increase/decrease in the vibration acceleration of the upper rotating body or the seat or the increase/decrease in the driving command value, there is a possibility that the occurrence of driving jerkiness will be erroneously detected.

More specifically, the travel operation device of a construction machine has left and right travel levers and left and right travel pedals that are located at the base ends of the left and right travel levers and operate in conjunction with the travel levers, and the travel operation can be performed in two ways: the operator operates the travel levers manually, or the operator operates the travel pedals with his or her foot.

When the vehicle body vibrates and shakes while traveling, the travel lever and travel pedal attached to the floor of the vehicle body shake, and the operator's body also shakes. At this time, the upper half of the operator's body is likely to shake significantly in response to the shaking of the vehicle body, but the lower half of the operator's body does not shake as much as the upper half because it is held by the driver's seat. For this reason, when the operator operates the travel lever manually, the shaking is transmitted to the travel lever, which also shakes significantly, and travel jerkiness is likely to occur due to the difference in the way the vehicle body shakes and the way the travel lever shakes. On the other hand, when the operator operates the travel pedal with his foot, the shaking of the travel pedal due to foot operation is small, and the difference between the way the vehicle body shakes and the way the travel pedal shakes is small, so travel jerkiness is unlikely to occur. Therefore, in a system that detects the occurrence of travel jerkiness by detecting the increase or decrease in the vibration acceleration of the upper rotating body or the seat or the increase or decrease in the travel command value, even if the occurrence of travel jerkiness can be detected when the operating lever is operated manually, if the travel pedal is operated with the foot, there is a possibility that travel jerkiness will be erroneously detected as occurring even though travel jerkiness does not occur.

If the occurrence of travel jerkiness is detected, a signal smoothing means such as a low-pass filter is used to suppress fluctuations in the operation signal (command value). However, if fluctuation suppression control is performed when the occurrence of travel jerkiness is erroneously detected, a delay in the transmission of the command value by the signal smoothing means occurs, reducing the responsiveness of travel operations. As a result, when the operator operates the travel pedal, the movement may differ from the operator's intention, and travel operability may be reduced.

The object of the present invention is to provide a hydraulic control system for construction machinery that prevents erroneous detection of the occurrence of traveling jerkiness when operating the travel control pedal and provides good travel operability.

In order to achieve the above object, the present invention provides a plurality of actuators including a traveling motor driven by pressure oil discharged from a hydraulic pump, a plurality of switching control valves including a traveling switching control valve that controls the flow of pressure oil discharged from the hydraulic pump and supplied to the traveling motor, a plurality of operation devices including a traveling operation device having a traveling operation lever and a traveling operation pedal located adjacent to a base end of the traveling operation lever and generating an operation signal according to the operation amount of the traveling operation lever and the traveling operation pedal, and a plurality of operation devices including a traveling operation device that calculates a target operation pressure according to the operation amount based on the operation signal of the traveling operation device, generates a command current according to the target operation pressure, and when it is determined that traveling jerkiness has occurred, In a hydraulic control system for a construction machine equipped with a controller that corrects a target operating pressure to limit the rate of change of the target operating pressure, and a traveling electromagnetic proportional control valve that generates a control operating pressure according to the command current and operates the traveling switching control valve, the system further includes a pressure sensor that detects the control operating pressure generated by the traveling electromagnetic proportional control valve, and the controller calculates a target operating pressure according to the operation amount of the traveling operation lever and the traveling operation pedal based on the operation signal of the traveling operation device, inputs the control operating pressure detected by the pressure sensor, calculates the pressure difference between the target operating pressure and the control operating pressure, and determines whether traveling jerkiness has occurred based on the change in the pressure difference.

In this way, in the present invention, whether or not traveling jerkiness has occurred is determined based on the change in the pressure difference between the target operating pressure and the control operating pressure, which is a parameter directly related to the shaking (vibration) of the traveling operation pedal, rather than the vibration of the vehicle body as in Patent Document 1. This makes it possible to accurately estimate the shaking of the traveling operation pedal, prevent erroneous detection of the occurrence of traveling jerkiness when the traveling operation pedal is operated, and obtain good traveling operability.

The present invention makes it possible to prevent erroneous detection of the occurrence of traveling jerkiness when operating the traveling operation pedal, and to obtain good traveling operability.

1 is a diagram showing the appearance of a hydraulic excavator, which is an example of a construction machine according to the present invention. FIG. 2 is a view of the driver's seat inside the cabin. 1 is a diagram showing a hydraulic drive device of a hydraulic control system according to a first embodiment of the present invention. FIG. FIG. 2 illustrates a controller of the hydraulic control system. FIG. 13 is a diagram showing changes in target operating pressure and control operating pressure when traveling jerkiness occurs. FIG. 4 is a functional block diagram showing the processing contents of a controller. 4 is a diagram showing a relationship between an operation signal and an operation amount for calculating an operation amount from the operation signal; FIG. FIG. 13 is a diagram showing a relationship between an operation amount and a target operating pressure for calculating a target operating pressure from the operation amount. 4 is a flowchart showing the overall flow of processing by the controller. 10 is a flowchart showing details of a command current generation process for an electromagnetic proportional control valve in steps S110, S130, S150, and S170 in the flowchart of FIG. 9. 10 is a flowchart showing details of a command current generation process for an electromagnetic proportional control valve in steps S110, S130, S150, and S170 in the flowchart of FIG. 9. 10 is a flowchart showing details of a command current generation process for an electromagnetic proportional control valve in steps S110, S130, S150, and S170 in the flowchart of FIG. 9. FIG. 1 shows the basic effect obtained by the cruise control of this embodiment, where the left side of the figure shows the changes in the target operating pressure and the control operating pressure before the application of the control of this embodiment, and the right side of the figure shows the changes in the target operating pressure and the control operating pressure after the application of the control of this embodiment. FIG. 11 is a functional block diagram showing the processing contents of a controller in a second embodiment of the present invention. 13 is a functional block diagram showing details of a state determination unit of the controller shown in FIG. 12. 14 is a flowchart showing an example of a process of a pressure difference threshold determining unit shown in FIG. 13 . FIG. 13 is a diagram showing the relationship between the boom angle and a first threshold coefficient K1 used in the processing of the pressure difference threshold determination unit. 13 is a diagram showing, in table form, the relationship between the second threshold coefficient when the traveling direction is a forward direction and the second threshold coefficient when the traveling direction is a reverse direction, which are used in the processing by the pressure difference threshold determination unit. FIG. 11 is a diagram showing a relationship between the operation torque of an operating pedal and a basic threshold value when the basic threshold value is determined based on the operation torque of the operating pedal; FIG. FIG. 13 is a functional block diagram showing details of a state determination unit of a controller according to a third embodiment of the present invention. 10 is a diagram showing the relationship between the difference between a target operating pressure and a control operating pressure used to estimate the magnitude of vibration of the operating pedal, and the magnitude of vibration of the operating pedal. FIG. 11 is a diagram showing the relationship between the magnitude of vibration of an operating pedal and a filter time constant τ. FIG.

The following describes an embodiment of the present invention with reference to the drawings.

First Embodiment
(hydraulic excavator)
FIG. 1 is a diagram showing the appearance of a hydraulic excavator, which is an example of a construction machine according to the present invention.

In Figure 1, the hydraulic excavator is roughly composed of a crawler-type lower track 1, an upper rotating body 2 that is rotatably mounted on the lower track 1, and a front work unit 3 that is attached to the front of the upper rotating body 2 so that it can rotate up and down and is used for work such as excavation.

The lower traveling body 1 is equipped with left and right traveling motors 1a, 1b and left and right crawlers 1c, 1d, and travel is achieved by driving the left and right crawlers 1c, 1d with the traveling motors 1a, 1b.

The upper rotating body 2 is equipped with a cabin 4, a prime mover 5, a hydraulic pump 6, and a rotation motor 2a, and the upper rotating body 2 is rotated to the right or left by the rotation motor 2a relative to the lower running body 1.

The front work machine 3 is composed of a boom 3a, an arm 3b, and a bucket 3c. The boom 3a is moved up and down by a boom cylinder 3d, the arm 3b is operated in the dumping direction (opening direction) or the crowding direction (scooping direction) by an arm cylinder 3e, and the bucket 3c is operated in the dumping direction or the crowding direction by a bucket cylinder 3f.

(Driver's cab)
FIG. 2 is a view of the driver's compartment in the cabin 4 as seen from the driver's seat side.

In FIG. 2, a cab 4a is formed in the cabin 4, and in the cab 4a, there are arranged a cab 51 where an operator sits, operation devices 52, 53 having left and right operation levers 52a, 53a for commanding the operation of the front work equipment 3 and the upper rotating body 2, and generating operation signals according to the operation amount of the operation levers 52a, 53a, and lever/pedal type operation devices (hereinafter sometimes referred to as travel operation devices) 54, 55 having left and right operation levers 54a, 55a and left and right operation pedals 54b, 55b for commanding the operation of the left and right crawlers 1c, 1d of the lower traveling body 1, and generating operation signals according to the operation amount of the operation levers 54a, 55a and the operation pedals 54b, 55b. The left and right operation pedals (hereinafter sometimes referred to as travel operation pedals or travel pedals) 54b, 55b are located adjacent to the base ends of the left and right operation levers (hereinafter sometimes referred to as travel operation levers or travel levers) 54a, 55a, respectively.

In addition, a gate lock lever 8 is provided on the entrance side of the cab 4a (to the left as viewed from the operator seated in the cab 17) which is rotated between an unlocked position (a lowered position that prevents the operator from getting on and off) and a locked position (an elevated position that allows the operator to get on and off). A gate lock switch 8a is provided at the base end of the gate lock lever 8 which is in a closed state when the gate lock lever 8 is in the unlocked position (lowered position) and in an open state when the gate lock lever 8 is in the locked position (elevated position). The gate lock switch 8a is electrically connected to the gate lock valve 48 (see Figure 2) of the hydraulic drive system. When the gate lock lever 8 is in the locked position, the gate lock valve 48 is in the OFF position and operation of the operation levers 52a, 53a, the travel operation levers 54a, 55a and the travel operation pedals 54b, 55b is disabled. When the gate lock lever 8 is switched to the unlocked position, the gate lock valve 48 is switched to the ON position, and the operation levers 52a, 53a, the travel operation levers 54a, 55a, and the travel operation pedals 54b, 55b can be operated.

In addition, a monitor 58 used to assist visibility is installed on the right side as viewed from the driver's seat 51, and is equipped with an input unit 58a used to set control thresholds and other vehicle settings.

(Operation device)
The operator sits in the driver's seat 51 and operates the operation lever 52a of the operation device 52 with his left hand and the operation lever 53a of the operation device 53 with his right hand. The operation devices 52 and 53 can be operated in any direction based on the cross directions of left, right, and up and down from the neutral position, respectively, and two actuators can be operated with one operation lever 52a and 53a. Operation of the operation lever 52a in the right direction R and left direction L commands the arm crowding and arm dumping operations of the arm cylinder 3e, and operation of the operation lever 52a in the forward direction F and backward direction R commands the right rotation and left rotation operations of the swing motor 2a. Operation of the operation lever 53a in the forward direction F and backward direction R commands the boom lowering and boom raising operations of the boom cylinder 3d, and operation of the operation lever 53a in the right direction R and left direction L commands the bucket dumping and bucket crowding operations of the bucket cylinder 3f.

The operator operates the operating lever 54a of the travel operating device 54 with his left hand and the operating lever 55a of the travel operating device 55 with his right hand, while operating the operating pedal 54b of the travel operating device 54 with his left foot and the operating pedal 55b of the travel operating device 55 with his right foot. The travel operating levers 54a, 55a can be operated in the forward direction F and the backward direction R from the neutral position, respectively, and operation of the travel operating lever 54a in the forward direction F and the backward direction R commands the operation of the left travel motor 1a in the forward direction and the backward direction, and operation of the travel operating lever 55a in the forward direction F and the backward direction R commands the operation of the right travel motor 1b in the forward direction and the backward direction.

The travel control pedals 54b, 55b can each be tilted forward and backward from a neutral position. Depressing the travel control pedal 54b in the forward direction F and the backward direction R instructs the left travel motor 1a to move forward and backward, similar to the operation of the travel control lever 54a, and depressing the travel control pedal 55b in the forward direction F and the backward direction R instructs the right travel motor 1b to move forward and backward, similar to the operation of the travel control lever 55a.

In this specification, the terms "forward," "backward," "rightward," and "leftward" refer to the forward, rear, rightward, and leftward directions of the upper rotating body 102, which is the vehicle body.

In this embodiment, the operating devices 52, 53 and the operating devices 54, 55 are electric operating devices, and each includes a signal generating unit 52c, 53c, 54c, 55c (see FIG. 2) that generates an electric signal as an operating signal. The operating lever 54a and the operating pedal 54b of the traveling operating device 54 each operate the same signal generating unit 54c to generate an electric signal, and the operating lever 55a and the operating pedal 55b of the traveling operating device 55 also each operate the same signal generating unit 55c to generate an electric signal.

The operating devices 52, 53 may be hydraulic pilot type that generates an operating pilot pressure as an operating signal.

(Hydraulic control system)
Fig. 3 is a diagram showing a hydraulic drive device of the hydraulic control system according to the first embodiment of the present invention, and Fig. 4 is a diagram showing a controller of the hydraulic control system. Fig. 4 also shows the configurations of the above-mentioned operating devices 52, 53 and operating devices 54, 55 in a schematic diagram.

In FIG. 3, the hydraulic drive system includes a prime mover 5 (e.g., a diesel engine), a hydraulic pump 6 driven by the prime mover 5, a plurality of actuators 1a, 1b, 2a, 3d, 3e, 3f including the left and right travel motors 1a, 1b driven by the pressurized oil discharged from the hydraulic pump 6, a control valve 19 incorporating a plurality of switching control valves 13, 14, 15, 16, 17, 18 including travel switching control valves 13, 14 that control the flow (flow rate and direction) of the pressurized oil discharged from the hydraulic pump 6 and supplied to the travel motors 1a, 1b, and a pilot relief valve 49 that discharges the pressurized oil maintained at a constant pressure by the pilot relief valve 49. , a pilot pump 47 that generates a pilot primary pressure, a plurality of electromagnetic proportional control valves 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 including traveling electromagnetic proportional control valves 20, 21, 22, 23 that are guided to the pilot primary pressure generated by the pilot pump 47 and generate a control pressure (hereinafter, sometimes referred to as a control operating pressure) according to a command current as a pilot secondary pressure and operate the traveling switching control valves 13, 14, and the aforementioned gate lock valve 48 that selects whether or not to guide the pilot primary pressure generated by the pilot pump 47 to the electromagnetic proportional control valves 20 to 31.

The control operating pressure generated by the electromagnetic proportional control valves 20-31 is guided to a pair of corresponding pressure receiving parts of the switching control valves 13-18, which are operated by the control operating pressure, and pressure oil is supplied to the corresponding actuators 1a-3f at a flow rate according to the control operating pressure.

The command current that causes the electromagnetic proportional control valves 20 to 31 to generate a control operating pressure is generated by the controller 34 shown in FIG. 4 based on the operating signals (electrical signals) of the operating devices 52, 53 and 54, 55, and the control valves 13 to 18 are switched by the control operating pressure, thereby driving multiple actuators 1a to 3f in response to the operating signals.

If the operating devices 52, 53 are hydraulic pilot type devices that generate operating pilot pressure as an operating signal, the electromagnetic proportional control valves 24-31 associated with the operating devices 52, 53 can be eliminated, and the operating pilot pressure generated by the operating devices 52, 53 can be introduced directly to the pressure receiving parts of the switching control valves 16-18 to switch the switching control valves 16-18.

The hydraulic control system according to this embodiment has a controller 34 shown in FIG. 4 and pressure sensors 35, 36, 37, 38 that detect the control operating pressure generated by the traveling electromagnetic proportional control valves 20 to 23. The controller 34 calculates a target operating pressure according to the amount of operation based on the operation signals (electrical signals) of the operating devices 52, 53 and the traveling operating devices 54, 55, generates a command current according to the target operating pressure, and, if it is determined that traveling jerkiness has occurred, corrects the target operating pressure of the traveling operating devices 54, 55 to limit the rate of change of the target operating pressure.

In Fig. 4, the operation devices 52, 53 and the operation devices 54, 55 are provided with signal generating units 52c, 53c, 54c, 55c (see Fig. 2) that generate electric signals as operation signals, as described above. In addition, the operation pedals 54b, 55b of the traveling operation devices 54, 55 are located at the base ends of the operation levers 54a, 55a, respectively, and
It works in conjunction with.

(Detection principle of traveling jerky)
The principle of detecting traveling jerky according to the present invention will now be described.

We will assume that travel jerkiness occurs when decelerating while traveling on rough ground by operating the travel control pedals 54b, 55b. Travel jerkiness is a phenomenon in which the vehicle body (upper rotating body 2) vibrates due to the influence of the road surface while the operator is traveling by operating the travel control devices 54, 55, and the vehicle body vibration is transmitted to the operator, making the operator's posture unstable, and the operator's shaking is transmitted to the operating levers 54a, 55a or operating pedals 54b, 55b that are being operated, causing the operating levers 54a, 55a or operating pedals 54b, 55b to shake in a phase different from the vehicle body vibration, causing the vehicle body to unintentionally accelerate or decelerate.

Figure 5 shows the changes in the target operating pressure (pressure calculated by the controller 34 based on the operation signal from the operation of the traveling operation pedals 54b, 55b) and the control operating pressure (pressure generated by the operation of the electromagnetic proportional control valves 20 to 23 by the command current) when such traveling jerkiness occurs. In the figure, the dotted line indicates the target operating pressure, and the solid line indicates the control operating pressure.

After the controller 34 calculates the target operating pressure based on the operation signal from the operation of the travel levers 54a, 55a or the travel pedals 54b, 55b, until the electromagnetic proportional control valves 20-23 are operated by the command current to generate the control operating pressure, there is a tracking delay time caused by the operation delay of the electromagnetic proportional control valves 20-23, and a pressure difference occurs between the target operating pressure and the control operating pressure as shown by the dotted and solid lines in Figure 5. If this pressure difference is defined as a value calculated by the target operating pressure-control operating pressure formula, in the process in which the operation amount of the travel operation pedals 54b, 44b decreases and the target operating pressure decreases, the pressure difference becomes a negative value, and due to the phase shift of the change (vibration) between the target operating pressure and the control operating pressure, the pressure difference decreases over time (the absolute value of the pressure difference increases). After that, when the operation amount changes from a decrease to an increase due to the vibration of the travel jerk and the target operating pressure increases, the pressure difference becomes a positive value, and as the increase rate of the target operating pressure increases over time, the subordinate pressure difference increases. After that, while the traveling jerk continues, the operation amount increases and decreases repeatedly, and the pressure difference also increases and decreases repeatedly.

In FIG. 5, time t1 is the point in time when the pressure difference becomes smaller than the preset threshold "-X" (the point in time when the absolute value of the pressure difference becomes larger than the threshold "X") during the process of the target operating pressure decreasing during deceleration of driving, and time t2 is the point in time when the pressure difference becomes larger than the preset threshold "X" during the process of the target operating pressure increasing as the operating amount changes from decreasing to increasing. In other words, time t2 is the point in time when a switch occurs between a driving state in which the pressure difference is larger than the threshold "X" and a driving state in which the pressure difference is smaller than the threshold "-X". The same is true for times t3 and t4.

In this specification, the threshold value "X" may be referred to as the first threshold value, and the threshold value "-X" may be referred to as the second threshold value. In addition, the running state in which the pressure difference is greater than the first threshold value "X" may be referred to as "State 1" or "First running state", and the running state in which the pressure difference is less than the second threshold value "-X" may be referred to as "State 2" or "Second running state".

The present invention focuses on the change in pressure difference when traveling jerkiness occurs, as shown in Figure 5, and determines whether traveling jerkiness has occurred.

Here, while FIG. 5 has been described as showing the case where the traveling jerkiness occurs when the traveling pedals 54b, 55b are operated, the pressure difference also occurs when the traveling levers 54a, 55a are operated, and the occurrence of traveling jerkiness can be detected. However, even if the vibration of the vehicle body is the same, the vibration of the traveling pedals 54b, 55b operated by the operator's foot is smaller than the vibration of the traveling levers 54a, 55a operated by the operator's hand. For this reason, if the occurrence of traveling jerkiness is detected by detecting the vibration of the vehicle body as in the past, when traveling by operating the traveling pedals with the foot, there is a possibility that the occurrence of traveling jerkiness will be erroneously detected even when traveling jerkiness does not occur.

In contrast, in the present invention, whether or not traveling jerkiness has occurred is determined based on the change in the pressure difference between the target operating pressure and the control operating pressure, which is directly related to the shaking (vibration) of the traveling pedals 54b, 55b, rather than the vibration of the vehicle body. More specifically, the present invention sets a first threshold value when the pressure difference is a positive value and a second threshold value when the pressure difference is a negative value, and determines whether or not the number of state switches between a first traveling state in which the pressure difference is greater than the first threshold value and a second traveling state in which the pressure difference is less than the second threshold value has reached a predetermined number of times, and determines that traveling jerkiness has occurred if the number of state switches has reached the predetermined number of times. This makes it possible to accurately estimate the shaking of the traveling pedals 54b, 55b, and prevents erroneous detection of the occurrence of traveling jerkiness when operating the traveling pedals 54b, 55b, thereby achieving good operability.

(controller)
FIG. 6 is a functional block diagram showing the processing contents of the controller 34.

The controller 34 has a target operating pressure calculation unit 34a, a state determination unit 34b, a target pressure correction unit 34c, and a solenoid valve control unit 34d.

The controller 34 calculates the target operating pressure according to the amount of operation based on the operation signals of the operating devices 52, 53 and the driving operating devices 54, 55 in the target operating pressure calculation unit 34a.

Figure 7 shows the relationship between the operation signal and the operation amount for calculating the operation amount from the operation signal, and Figure 8 shows the relationship between the operation amount and the target operation pressure for calculating the target operation pressure from the operation amount.

The controller 34 stores the relationship between the operation signal and the operation amount as shown in FIG. 7 and the relationship between the operation amount and the target operation pressure as shown in FIG. 8 for each of the operation levers and operation pedals of the operation devices 52, 53 and the traveling operation devices 54, 55, and in the target operation pressure calculation unit 34a, the operation signals of the operation levers and operation pedals of the operation devices 52, 53 and the traveling operation devices 54, 55 are calculated by referring to the relationship between the operation signal and the operation amount shown in FIG. 7, and the calculated operation amount is calculated by referring to the relationship between the operation amount and the target operation pressure shown in FIG. 8 to calculate the corresponding target operation pressure.

Then, the controller 34 performs the following processing in the state determination unit 34b.

1. The controller 34 inputs the control operating pressure detected by the pressure sensors 35 to 38, calculates the pressure difference between the target operating pressure calculated by the target operating pressure calculation unit 34a and the control operating pressure, and determines whether traveling jerkiness has occurred based on the change in the pressure difference.

2. More specifically, the controller 34 sets, as thresholds, a first threshold "X" when the pressure difference is a positive value and a second threshold "-X" when the pressure difference is a negative value, and determines whether the number of state switches between a first running state in which the pressure difference is greater than the first threshold "X" and a second running state in which the pressure difference is less than the second threshold "-X" has reached a first predetermined number of times, and determines that running jerkiness has occurred when the number of state switches between the first running state and the second running state has reached the first predetermined number of times.

3. In this case, the controller 34 determines whether the number of state changes has reached a first predetermined number within a first predetermined time, and determines that traveling jerkiness has occurred if the number of state changes has reached the first predetermined number within the first predetermined time.

4. The first predetermined number of times is preferably 1 to 3 times.

5. After the number of state switches reaches a first predetermined number and it is determined that running jerkiness has occurred, the controller 34 further determines whether the number of state switches reaches a second predetermined number, and if the number of state switches reaches the second predetermined number, it determines that the running jerkiness is continuing.

6. In this case, the controller 34 determines whether the number of state changes has reached a second predetermined number within the second predetermined time, and if the number of state changes has reached the second predetermined number within the second predetermined time, determines that the running jerky is continuing, and if the number of state changes has not reached the second predetermined number within the second predetermined time, determines that the running jerky has ended.

7. The second predetermined number of times is preferably 1 to 2 times.

When the state determination unit 34b of the controller 34 determines that traveling jerkiness has occurred, the target pressure correction unit 34c corrects the target operating pressure to limit the rate of change of the target operating pressure, and the solenoid valve control unit 34d generates a command current according to the corrected target operating pressure and outputs it to the solenoid proportional control valves 20 to 23.

Meanwhile, in the target operating pressure calculation unit 34a of the controller 34, in response to the operation signals of the operating levers of the operating devices 52 and 53, the controller 34 calculates target operating pressures other than for traveling using the relationship between the operation signal and the operation amount shown in FIG. 7 and the relationship between the operation amount and the target operating pressure shown in FIG. 8, in the same way as in the case of the operation signals of the operating levers and the operating pedals of the traveling operating devices 54 and 55, and sends the target operating pressure directly to the solenoid valve control unit 34d, generates a command current according to the target operating pressure, and outputs it to the solenoid proportional control valves 24 to 31.

(Controller control flow)
Next, the processing of the controller 34 that is related to the operation signals of the operating levers and operating pedals of the travel operating devices 54, 55 will be described in detail with reference to flow charts in FIG. 9, FIG. 10A, FIG. 10B and FIG. 10C.

Figure 9 is a flowchart showing the overall flow of processing by the controller 34. Figures 10A, 10B, and 10C are flowcharts showing the details of the command current generation processing for the proportional solenoid control valves 20 to 23 in steps S110, S130, S150, and S170 of the flowchart in Figure 9.

In FIG. 9, the controller 34 judges whether the left travel lever 54a or the travel pedal 54b (left travel lever/pedal) is operated forward and the operation signal for the left forward direction generated by the signal generating unit 54c is input (step S100), and if the judgment is YES, the controller 34 performs a process of generating and outputting a command current for the electromagnetic proportional control valve 20 for the left forward direction (step S110). If the judgment in step S100 is NO, the controller 34 judges whether the right travel lever 55a or the travel pedal 55b (right travel lever/pedal) is operated forward and the operation signal for the right forward direction generated by the signal generating unit 55c is input (step S120), and if the judgment is YES, the controller 34 performs a process of generating and outputting a command current for the electromagnetic proportional control valve 22 for the right forward direction (step S130).

If the determination in step S120 is NO, the controller 34 determines whether the left travel lever 54a or the travel pedal 54b (left travel lever/pedal) has been operated backward and the operation signal for the left reverse direction generated by the signal generating unit 54c has been input (step S140), and if the determination is YES, the controller 34 performs a process of generating and outputting a command current for the electromagnetic proportional control valve 21 for the left reverse direction (step S150). If the determination in step S140 is NO, the controller 34 determines whether the right travel lever 55a or the travel pedal 55b (right travel lever/pedal) has been operated backward and the operation signal for the right reverse direction generated by the signal generating unit 55c has been input (step S160), and if the determination is YES, the controller 34 performs a process of generating and outputting a command current for the electromagnetic proportional control valve 23 for the right reverse direction (step S170).

In this way, the controller 34 operates the electromagnetic proportional control valves 20 to 23 for travel by operating the travel levers 54a, 55a and the travel pedals 54b, 55b, generating a control operating pressure.

The controller 34 also independently controls the left side forward operation, the right side forward operation, the left side reverse operation, and the right side reverse operation.

Next, the details of the command current generation process in steps S110, S130, S150, and S170 of the flowchart in FIG. 9 will be described using the flowcharts shown in FIG. 10A, FIG. 10B, and FIG. 10C.

The processing of steps S110, S130, S150, and S170 is the same except for whether the travel lever/pedal is left or right and whether the operation direction is forward or backward, so we will explain the processing of step S110 when the travel lever/pedal is the left travel lever 54a and travel pedal 54b and the operation direction is forward.

In FIG. 10A, the controller 34 first inputs the operation signal of the travel lever 54a or travel pedal 54b (left travel lever/pedal) and calculates the operation amount (step S1). As described above, this calculation of the operation amount is performed using the relationship between the operation signal and the operation amount shown in FIG. 7. Next, the controller 34 inputs the detection signal of the pressure sensor 35 and obtains the control operation pressure generated by the electromagnetic proportional control valve 20 for the left forward direction (step S2).

The controller 34 calculates a target operating pressure according to the operation amount of the travel lever/pedal calculated in step S1 (step S3). As described above, the target operating pressure is calculated using the relationship between the operation amount and the target operating pressure shown in FIG. 8. Next, the controller 34 calculates the difference (pressure difference) D between the target operating pressure calculated in step S3 and the control operating pressure acquired in step S2 using the following formula (step S4).

D = target operating pressure - control operating pressure Then, the controller 34 judges whether the pressure difference D is greater than the first threshold value "X" (positive value) of the driving operating pressure difference (step S5), and if the judgment is YES, stores the driving state as "State 1" (step S6). "State 1" corresponds to state 1 at time t2 in FIG. 5.

Next, the controller 34 judges whether the pressure difference D is smaller than a second threshold value "-X" (negative value) of the driving operation pressure difference (step S7), and if the judgement is YES, stores the driving state as "State 2" (step S8). "State 2" corresponds to state 2 at time t1 in Fig. 5. If the judgement in step S5 is NO, the process proceeds to step S7 to make a similar judgement, and if the judgement is YES, the process proceeds to step S8 to store the driving state as "State 2" (step S8).

The first and second pressure difference thresholds "X" and "-X" are determined based on the magnitude of the effect of the travel pedals 54b and 55b on the vibration of the vehicle body (upper rotating body 2) when traveling with the travel pedals 54b and 55b operated by foot, and are determined based on the operating torque of the travel pedals 54b and 55b and the trackability of the control operating pressure to the target operating pressure.

When the pilot primary pressure generated by the pilot pump 47 is, for example, 4 MPa, the first threshold value "X" is, for example, 0.1 MPa, and the second threshold value "-X" is, for example, -0.1 MPa.

In addition, as will be described in the second embodiment below, the first threshold value "X" and the second threshold value "-X" can be changed depending on the posture of the front work implement 3 and the traveling direction of the vehicle body (forward or reverse), thereby reducing false detection of traveling jerkiness.

The controller 34 then determines whether the previously stored running state was "State 1" and the currently stored running state is "State 2" (whether the running state has switched from State 1 to State 2), or whether the previously stored running state was "State 2" and the currently stored running state is "State 1" (whether the running state has switched from State 2 to State 1) (step S9), and if the determination is YES, adds 1 to the running jerkiness determination count value JC (step S10). The initial setting of the running jerkiness determination count value JC is 0.

The YES determination in step S9 corresponds to the case in FIG. 5 where "State 2" occurs at time t1 and switches to "State 1" at time t2, and where a single switch between "State 1" (first running state) and "State 2" (second running state) occurs.

After step S10, proceed to step S11 in Figure 10B.

If the determination in step S7 is NO, proceed to step S9, where a similar determination is made, and if the determination is YES, perform processing in step S10, and then proceed to step S11 in FIG. 10B.

In step S11 of FIG. 10B, the controller 34 determines whether the previous running jerkiness determination is invalid as an initial setting. If the determination in step S11 is YES, it further determines whether the running jerkiness determination count value JC is greater than 0 (JC>0) (step S12), and if the determination is YES, it adds 1 to the running determination time count value TC (step S13). The initial setting of the running determination time count value TC is 0. Also, if the control cycle of the flowchart is 0.01 seconds, the running determination time count value TC of "1" corresponds to 0.01 seconds. If the determination in step S12 is NO, the process proceeds to step S18.

The process when the determination is NO in step S11 will be described later.

After the processing of step S13, the controller 34 judges whether the count value TC of the running judgment time is smaller than the threshold value Y1 (first predetermined time) of the running judgment time (TC<Y1) (step S14), and if the judgment is YES, it further judges whether the count value JC of the running jerkiness judgment is equal to or greater than the threshold value Z1 (first predetermined number of times) of the running jerkiness judgment (JC≧Z1) (step S15).

In this embodiment, the time conversion value of the threshold value Y1 (first predetermined time) is, for example, 3 seconds, and when the control cycle of the flowchart is 0.01 seconds, the threshold value Y1 is, for example, "300." The threshold value Z1 (first predetermined number of times) is, for example, "1 time."

The threshold value Y1 (first predetermined time) of the travel judgment time in step S14 and the threshold value Z1 (first predetermined number of times) of the travel jerkiness judgment in step S15 are threshold values for judging whether the frequency of occurrence of the travel jerkiness judgment count value JC, i.e., the number of times that the judgment YES in step S9 occurs within a predetermined time (in this embodiment, the frequency of state switching between state 1 and state 2) has reached the number of times that travel jerkiness can be considered to have occurred. When the threshold value Y1 and threshold value Z1 are set as described above and the judgments in steps S14 and S15 are both YES, the controller 34 judges that a YES judgment in step S9 has occurred once within 3 seconds (300 control cycles) (in the operating state of FIG. 5, a switch between state 2 at time t1 and state 1 at time t2 has occurred once), and judges that travel jerkiness has occurred.

The period during which the travel pedals 54b, 55b vibrate when travel jerk occurs varies depending on the specifications of the hydraulic excavator, and the threshold value Y1 of the travel determination time in step S14 is set based on the vibration period of the travel pedals 54b, 55b.

In addition, the threshold Z1 (first predetermined number of times) for determining whether traveling is jerkiness is determined in step S15 is determined based on the frequency with which the traveling state switches between "State 1" and "State 2" during traveling as intended by the operator, not during traveling vibration. If the number of times for the threshold Z1 for determining whether traveling is jerkiness is set to a small value, the time until the traveling control is activated when traveling jerkiness begins is shortened, so the effects of traveling jerkiness can be quickly eliminated, but the possibility of erroneous detection of traveling jerkiness increases accordingly. If the threshold Z1 for determining whether traveling is jerkiness is set to a large value, the possibility of erroneous detection of traveling jerkiness is reduced, but the time until the traveling control is activated when traveling jerkiness begins is lengthened, so the vehicle becomes more susceptible to the effects of traveling jerkiness. The threshold Z1 for determining whether traveling is jerkiness is determined by taking into account the balance between the speed at which the effects of traveling jerkiness are eliminated and the prevention of erroneous detection of traveling jerkiness.

In this embodiment, the threshold Z1 (first predetermined number of times) is set to one time, but it may be set to two or three times to reduce the possibility of erroneous detection. This threshold can be changed, for example, by operating the input unit 58a of the monitor 58 shown in FIG. 2 to select a desired threshold and transmitting the selected threshold information to the controller 34.

If the threshold Z1 for determining whether traveling jerk occurs in step S15 is set to "2 times" or more, and if the number of times that the determination in step S9 in FIG. 10B results in YES is one, the determination in step S15 will be NO, and the process will proceed to step S18.

Next, if the determination in step S15 is YES, the controller 34 enables the running jerkiness determination, resets the running jerkiness determination count value JC and the running determination time count value TC to 0 in order to determine whether the running jerkiness continues (step S16), and proceeds to step S18.

On the other hand, if the determination in step S14 is NO, it means that it has been determined that no traveling jerkiness has occurred within the threshold value Y1 of the traveling determination time, and the controller 34 resets the traveling jerkiness determination count value JC and the traveling determination time count value TC to 0 in order to continue to determine whether traveling jerkiness has occurred (step S17), and proceeds to step S18.

In step S18, the controller 34 determines whether the traveling jerk determination is valid, and if the determination is YES, it applies a first-order low-pass filter to the target operating pressure to correct the target operating pressure (step S19).

Here, the filter time constant τ of the first-order low-pass filter acting on the target operating pressure is determined based on the degree of influence of the vibration of the travel lever/pedal of the actual vehicle body (upper rotating body 2) on the travel acceleration/deceleration. As will be described in a third embodiment later, the filter time constant τ may be changed based on the magnitude of the pressure difference D between the target operating pressure and the control operating pressure, thereby making it possible to correct the action of the filter according to the vibration amplitude of the pedal.

Next, the controller 34 controls the electromagnetic proportional control valves 20 to 23 for driving in accordance with the target operating pressure (step S20).

If the determination in step S18 is NO, the controller 34 proceeds directly to step S20 and controls the electromagnetic proportional control valves 20 to 23 for driving according to the target operating pressure.

Next, we will explain what happens if the result of step S11 is NO.

If the determination in step S11 is NO, it means that it has been determined in step S16 that the running jerkiness determination has been enabled (running jerkiness has occurred), and the controller 34 performs processing equivalent to steps S13 to S17 to determine whether running jerkiness continues thereafter.

That is, if the determination in step S11 is NO, the controller 34 adds 1 to the count value TC of the running judgment time (step S21), and in step S16 or S17, determines whether the count value TC of the running judgment time after resetting the count value TC of the running judgment time to 0 is smaller than the threshold value Y2 (second predetermined time) of the running judgment time continuation (TC<Y2) (step S22), and if the determination is YES, further determines whether the count value JC of the running jerkiness determination is equal to or greater than the threshold value Z2 (second predetermined number of times) of the running jerkiness continuation determination (JC≧Z2) (step S23).

The threshold value Y2 (second predetermined time) for the duration of the running determination time is set to "150", for example, equivalent to 1.5 seconds, which is shorter than the threshold value Y1 (first predetermined time) for the running determination time in step S14 of FIG. 10B, taking into account the damping of vibrations due to the filter control in step S19 of FIG. 10B, and the threshold value Z2 (second predetermined number of times) for the duration of the running jerkiness determination is set to "1 time", for example, the same as the threshold value Z1 (first predetermined number of times) for the running jerkiness determination in step S15 of FIG. 10B.

If the determination in step S23 is YES, which corresponds to the determination in step S9 being YES, the controller 34 determines that the traveling jerkiness is continuing and resets the traveling jerkiness determination count value JC and the traveling determination time count value TC to 0 in order to continue monitoring the continuation of the traveling jerkiness (step S24).

If the determination in step S23 is NO, which means that the determination in step S9 is NO and 1 was not added to the running jerk determination count value JC in step S10, the process proceeds to step S18 described above, and the processes in steps S18, S19, S20, and S11 are performed.

If the determination in step S22 is NO, which means that the running jerkiness has ended within the threshold value Y2 of the running determination time duration, the controller 34 resets the running jerkiness determination count value JC and the running determination time count value TC to 0, and invalidates the running jerkiness determination (step S25).

If the determination in step S23 is NO, proceed to step S18 described above.

(Example of operation)
10A, 10B, and 10C will be further described using an operation example in which the threshold value Z1 for determining whether traveling jerkiness occurs is set to one time.

~ Example of operation 1 ~
During normal driving.

During normal driving, the pressure difference between the target operating pressure and the control operating pressure does not exceed the first threshold "X" and the second threshold "-X", and the judgments in steps S5, S7, and S9 are NO. Therefore, the driving jerk judgment remains disabled as the initial setting, and in step S20, the electromagnetic proportional control valves 20 to 23 for driving are controlled according to the target operating pressure.

The flow of control in this case is as follows:

S1 to S4 → S5 (NO) → S7 (NO) → S9 (NO) → S11 (YES) → S12 (NO) → S18 (NO) → S20 (no target operating pressure correction)
~ Example 2 ~
5 occurs during normal driving, but the state 2 shown in Fig. 5 does not change from state 2 to state 1, and the determination result of the occurrence of traveling jerkiness is not reached. In this case, the determination in step S9 is NO, and the count value JC for the traveling jerkiness determination remains at the initial setting of 0. Therefore, the determination in step S12 is also NO, the traveling jerkiness determination remains invalid, and in step S20, the traveling electromagnetic proportional control valves 20 to 23 are controlled according to the target operating pressure.

The flow of control in this case is as follows:

S1 to S4 → S5 (NO) → S7 (YES) → S8 → S9 (NO) → S11 (YES) → S12 (NO) → S18 (NO) → S20 (no target operating pressure correction)
~ Example 3 ~
When a transition from state 2 to state 1 shown in FIG. 5 occurs once, and it is determined that a running jerk has occurred, the running jerk ends within the threshold Y2 of the running determination time continuation (3-1)
<The transition between state 2 and state 1 occurs once, and the operation until it is determined that running jerkiness has occurred>
After step S5 or step S7 is judged as YES and step S9 is judged as NO, if step S7 or step S5 is judged as YES and step S9 is judged as YES (when a switch between state 1 and state 2 occurs), in step S10, the count value JC of the running jerkiness judgment becomes 1 (it is judged that running jerkiness has occurred). Therefore, the judgment in step S12 becomes YES, and in step S13, 1 is added to the count value TC of the running judgment time. At this time, the count value TC of the running judgment time is within the threshold value Y1 of the running judgment time, and in step S14, it is judged as YES. Also, as described above, in this operation example, the threshold value Z1 of the running jerkiness judgment is 1 (1 time), the judgment in step S15 becomes YES, and in step S16, the running jerkiness judgment is enabled. As a result, the determination in step S18 becomes YES, and in step S19 a correction is made by applying a first-order low-pass filter to the target operating pressure. In step S20, the electromagnetic proportional control valves 20 to 23 for traveling are controlled in accordance with the corrected target operating pressure, and the drive of the traveling motors 1a, 1b is controlled.

The flow of control in this case is as follows:
(1) If the driving condition previously stored was "Condition 1"
S1 to S4 → S5 (NO) → S7 (YES) → S8 → S9 (YES) → S10 → S11 (YES) → S12 (YES) → S13 → S14 (YES) → S15 (YES) → S16 → S18 (YES) → S19 → S20 (with target operating pressure correction)
(2) If the driving condition previously stored was "Condition 2"
S1 to S4 → S5 (YES) → S6 → S7 (NO) → S9 (YES) → S10 → S11 (YES) → S12 (YES) → S13 → S14 (YES) → S15 (YES) → S16 → S18 (YES) → S19 → S20 (Target operating pressure correction available)
(3-2)
<Actions taken after it is determined that running jerky has occurred>
Thereafter, if no switching between state 1 and state 2 occurs, step S9 is NO, and the determination of traveling jerkiness is enabled by the processing of step S16, so the determination of step S11 is also NO. Furthermore, within the time of threshold Y2 for the traveling determination time continuation in step S22, the determination of step S22 is YES and the determination of step S23 is NO. Therefore, the processing proceeds to steps S18, S19, and S20, the target operating pressure is corrected, and the electromagnetic proportional control valves 20 to 23 are controlled based on the corrected target operating pressure, and the drive of the traveling motors 1a and 1b is controlled.

The flow of control in this case is as follows:

S1 to S4 → S5 (YES) → S6 → S7 (NO) → S9 (NO) → S11 (NO) → S21 → S22 (YES) → S23 (NO) → S18 (YES) → S19 → S20 (with target operating pressure correction)
After it is determined that traveling jerkiness has occurred in this manner, the target operating pressure is corrected, and the electromagnetic proportional control valves 20 to 23 are controlled based on the corrected target operating pressure, thereby controlling the drive of the traveling motors 1a, 1b.

(3-3)
<Operation at the end of the running jerky>
Thereafter, when the traveling jerkiness ends within the threshold Y2 of the traveling judgment time duration in step S22, the judgment in step S22 becomes NO, and in step S25, the count value JC of the traveling jerkiness judgment and the count value TC of the traveling judgment time are reset to 0, and the traveling jerkiness judgment is invalidated. As a result, the judgment in step S18 becomes NO, the correction process of the target operating pressure in step S19 is terminated, and in step S20, the electromagnetic proportional control valves 20 to 23 for traveling are controlled in accordance with the target operating pressure, and the drive of the traveling motors 1a and 1b is controlled.

The flow of control in this case is as follows:

S1 to S4 → S5 (YES) → S6 → S7 (NO) → S9 (NO) → S11 (NO) → S21 → S22 (NO) → S25 → S18 (NO) → S20 (no target operating pressure correction)
~ Operation example 4 ~
After the operation of (3-2) in the operation example 3, if a switch between state 1 and state 2 occurs again within the time of the threshold Y2 of the driving determination time continuation,
After the operation of (3-2) in the operation example 3, if the judgment in step S5 or step S7 is YES and the judgment in step S9 is YES, the count value JC of the traveling jerkiness judgment becomes 1 in step S10. Also, since the traveling jerkiness judgment is enabled by the processing in step S16, the judgment in step S11 is NO, and the processing proceeds to steps S21, S22, and S23. Then, the judgment in step S23 becomes YES (it is judged that the traveling jerkiness is continuing), and in order to continue judging the continuation of the traveling jerkiness in step S24, the count value JC of the traveling jerkiness judgment and the count value TC of the traveling judgment time are reset to 0. After this, the processing proceeds to steps S18, S19, and S20, the target operating pressure is corrected, and the electromagnetic proportional control valves 20 to 23 are controlled based on the corrected target operating pressure, and the drive of the traveling motors 1a and 1b is controlled.

The flow of control in this case is as follows:
(1) If the driving condition previously stored was "Condition 1"
S1 to S4 → S5 (NO) → S7 (YES) → S8 → S9 (YES) → S11 (NO) → S21 → S22 (YES) → S23 (YES) → S24 → S18 (YES) → S19 → S20 (with target operating pressure correction)
(2) If the driving condition previously stored was "Condition 2"
S1 to S4 → S5 (YES) → S6 → S7 (NO) → S9 (YES) → S11 (NO) → S21 → S22 (YES) → S23 (YES) → S24 → S18 (YES) → S19 → S20 (Target operating pressure correction available)
Thereafter, when the driving jerk ends within the threshold Y2 of the driving judgment time duration in step S22, the correction process of the target operating pressure in step S19 ends as shown in (3-3) of operation example 3, and in step S20, the electromagnetic proportional control valves 20 to 23 for driving are controlled according to the target operating pressure, and the drive of the driving motors 1a, 1b is controlled.

(effect)
According to the present embodiment configured as above, the following effects can be obtained.

1. Figure 11 shows the basic effect obtained by the driving control of this embodiment. The left side of the figure shows the changes in the target operating pressure and the control operating pressure before the application of the control of this embodiment, and the right side of the figure shows the changes in the target operating pressure and the control operating pressure after the application of the control of this embodiment.

By performing the driving control of this embodiment, the target operating pressure is corrected as shown by the dotted line on the right side of Figure 11, and the driving electromagnetic proportional control valves 20 to 23 are controlled by a command current generated based on the corrected target operating pressure, so that the control operating pressure output from the electromagnetic proportional control valves 20 to 23 is corrected as shown by the solid line on the right side of Figure 11, and the effects of driving jerkiness can be ended early.

2. In this embodiment, whether or not traveling jerkiness has occurred is determined based on the change in the pressure difference between the target operating pressure and the control operating pressure, which is directly related to the shaking (vibration) of the traveling operation pedals 54b, 55b, rather than the vibration of the vehicle body, i.e., the number of state changes in which the pressure difference exceeds the threshold value "X" or "-X" (when the number of state changes between the first traveling state in which the pressure difference is greater than the first threshold value "X" and the second traveling state in which the pressure difference is less than the second threshold value "-X" reaches a first predetermined number), so that the shaking of the traveling pedals 54b, 55b can be accurately estimated and erroneous detection of the occurrence of traveling jerkiness when the traveling operation pedals 54b, 55b are operated can be prevented. Therefore, it is possible to prevent a decrease in the responsiveness of the traveling operation due to a primary low-pass filter (signal smoothing means) that occurs when the occurrence of traveling jerkiness is erroneously detected, and good operability can be obtained.

3. Furthermore, the controller 34 determines whether the number of state changes reaches a first predetermined number Z1 within a first predetermined time Y1, and determines that traveling jerkiness has occurred if the number of state changes reaches the first predetermined number Z1 within the first predetermined time Y1. Therefore, the occurrence of traveling jerkiness can be determined based on the frequency of state changes, the shaking of the traveling pedals 54b, 55b can be more accurately estimated, and erroneous detection of the occurrence of traveling jerkiness can be further reduced.

4. After the number of state switches reaches a first predetermined number Z1 and it is determined that running jerkiness has occurred, the controller 34 further determines whether the number of state switches reaches a second predetermined number Z2, and if the number of state switches reaches the second predetermined number Z2, it determines that the running jerkiness is continuing. This makes it possible to accurately estimate the continuation of running jerkiness after the occurrence of running jerkiness.

5. The controller 34 also determines whether the number of state changes reaches a second predetermined number Z2 within a second predetermined time Y2, and determines that the running jerky is continuing if the number of state changes reaches the second predetermined number Z2 within the second predetermined time Y2, and determines that the running jerky has ended if the number of state changes does not reach the second predetermined number Z2 within the second predetermined time Y2. This allows the continuation of the running jerky to be determined based on the frequency of state changes, and allows the continuation of the running jerky to be more accurately estimated.

Second Embodiment
A second embodiment of the present invention will be described with reference to FIGS. 1, 2, 12 and 14 to 17. FIG.

In FIG. 1, the hydraulic control system of this embodiment is equipped with an angle sensor 60 that detects the attitude of the front work unit 3 of the hydraulic excavator. The angle sensor 60 is an angle sensor such as an inertial sensor that is provided on the boom 3a and detects the angle of the boom 3a with respect to the horizontal direction (boom angle).

Figure 12 is a functional block diagram showing the processing contents of the controller in the second embodiment of the present invention, and Figure 13 is a functional block diagram showing the details of the state determination unit 34b of the controller 34.

In FIG. 12, the controller 34 of this embodiment receives the operation signals of the operation devices 52, 53 and the travel operation devices 54, 55, the detection signals of the pressure sensors 35 to 38, and the detection signal of the angle sensor 60.

In FIG. 13, the state determination unit 34b of the controller has a state determination processing unit 34bA and a pressure difference threshold determination unit 34bB. The state determination processing unit 34bA inputs the operation signals of the operation devices 52, 53 and the driving operation devices 54, 55, and the detection signals of the pressure sensors 35 to 38, and performs the above-mentioned processing explained using the flowcharts shown in FIG. 9 and FIG. 10A to FIG. 10C.

The pressure difference threshold determination unit 34 b B acquires posture information (boom angle) of the front work unit 3 based on the detection signal of the angle sensor 60, and determines a first threshold value "X" and a second threshold value "-X" of the pressure difference so that the absolute values become larger as the front work unit 3 rotates downward and the posture of the front work unit 3 approaches horizontal.

The pressure difference threshold determination unit 34 b B determines whether the driving direction indicated by the operation signal is a forward direction or a reverse direction based on the operation signal of the driving operation device 54, 55, and determines a first threshold value "X" and a second threshold value "-X" of the pressure difference so that the absolute value is larger when the driving direction is the forward direction than when the driving direction is the reverse direction.

Fig. 14 is a flowchart showing an example of the processing of the pressure difference threshold determination unit 34 b B. Fig. 15 is a diagram showing the relationship between the boom angle and the first threshold coefficient K1 used in the processing of the pressure difference threshold determination unit 34 b B, and Fig. 16 is a diagram showing, in a table format, the relationship between the second threshold coefficient when the traveling direction is the forward direction and the second threshold coefficient when the traveling direction is the reverse direction.

In Fig. 15, the pressure difference threshold determination unit 34bB acquires the boom angle as the attitude information of the boom 3a from the detection signal of the angle sensor 60, and calculates the corresponding first threshold coefficient K1 by referring to the relationship between the boom angle and the first threshold coefficient K1 shown in Fig. 15 (step S210). The relationship between the boom angle and the first threshold coefficient K1 in Fig. 16 is set so that the first threshold coefficient K1 increases as the boom angle decreases (as the front work implement 3 approaches a horizontal attitude), and is stored in the controller 34.

Next, the pressure difference threshold determination unit 34bB determines whether the driving direction indicated by the operation signal is forward or backward based on the operation signal of the driving operation device 54, 55, and determines the second threshold coefficient K2 corresponding to the determined driving direction by referring to the relationship between the driving direction and the second threshold coefficient K2 shown in Fig. 16 (step S220). In the table of Fig. 17, the relationship between the driving direction and the second threshold coefficient K2 is set such that the second threshold coefficient K2 is smaller than 1, for example, 0.8, when the driving direction is forward, and the second threshold coefficient K2 is larger than 1, for example, 1.2, when the driving direction is backward, and is stored in the controller 34.

Next, the pressure difference threshold value determining unit 34 b B calculates the first threshold value "X" and the second threshold value "-X" of the pressure difference from the following formula (step S230).

First threshold "X" = Basic threshold "X0" x K1 x K2
Second threshold "-X" = Basic threshold "-X0" x K1 x K2
The basic threshold value "X0" is a value determined in advance based on the operation torque of the traveling pedals 54b, 55b, and is stored in the controller 34.

Figure 17 shows the relationship between the operating torque of the travel pedals 54b, 55b and the basic threshold value "X0" when the basic threshold value "X0" is determined based on the operating torque of the travel pedals 54b, 55b. As shown in this figure, the basic threshold value "X0" is set at the time of shipment of the machine so that it increases as the operating torque of the travel pedals 54b, 55b decreases.

The operating torque of the travel pedals 54b, 55b affects the ease with which the operator depresses the travel pedals 54b, 55b with their feet (depressing force), and the vibration (sway) of the travel pedals 54b, 55b caused by foot operation in response to the vibration of the vehicle body becomes greater when the operating torque of the travel pedals 54b, 55b is small than when it is large, and therefore the absolute values of the first threshold value "X" and the second threshold value "-X" must be increased accordingly. On the other hand, there is some variation in the operating torque of the travel pedals 54b, 55b when the machine is shipped, and the first threshold value "X" and the second threshold value "-X" must be set taking this variation into consideration.

As shown in FIG. 17, by setting the basic threshold value "X0" so that it increases as the operating torque of the travel pedals 54b, 55b decreases, the variation in the operating torque of the travel pedals 54b, 55b at the time of shipment of the machine is absorbed, and the first threshold value "X" and the second threshold value "-X" become appropriate values.

In this embodiment, by determining the first threshold value "X" and the second threshold value "-X" of the pressure difference as described above, the first threshold value "X" and the second threshold value "-X" of the pressure difference are determined so that the absolute value becomes larger as the front working machine 3 rotates downward and the attitude of the front working machine 3 approaches horizontal. In addition, the first threshold value "X" and the second threshold value "-X" of the pressure difference are determined so that the absolute value becomes larger when the traveling direction indicated by the operation signal of the traveling operation devices 54, 55 is the forward direction than when it is the reverse direction.

This embodiment provides the following advantages:

The magnitude (amplitude) of the vibration of the vehicle body when a hydraulic excavator travels on rough ground varies depending on the posture of the front work implement 3 and the direction of travel, and the likelihood of travel jerkiness also varies.

In other words, when the boom angle is small and the front work implement 3 is positioned close to horizontal, the vehicle body is more likely to sway, resulting in greater vibration of the vehicle body and making it easier for traveling jerkiness to occur. On the other hand, when the boom angle is large and the front work implement 3 is positioned close to vertical, the vehicle body is less likely to sway, resulting in less vibration of the vehicle body and making traveling jerkiness less likely to occur.

When driving the vehicle forward, the operator presses the control pedal forward F (see Figure 2), which causes the upper half of the operator's body to move away from the seat back, making the operator's upper body more likely to sway and making traveling jerky more likely to occur. On the other hand, when driving the vehicle backward, the operator presses the control pedal backward R (see Figure 2), which causes the upper half of the operator's body to be held against the seat back, making the operator's upper body less likely to sway and making traveling jerky less likely to occur.

For this reason, if the same first threshold value "X" and second threshold value "-X" are used regardless of the posture or traveling direction of the front work implement 3, there is a possibility that the occurrence of traveling jerkiness will be erroneously detected.

In this embodiment, as described above, the first threshold value "X" and the second threshold value "-X" are corrected according to the posture and traveling direction of the front work machine 3, so that erroneous detection of the occurrence of traveling jerkiness can be reduced.

In this embodiment, an angle sensor 60 that detects the angle of the boom 3a (boom angle) is used to detect the posture of the front work unit 3, but an angle sensor that detects the angle of the arm 3b (arm angle) in addition to the boom angle may be further provided, and the posture of the front work unit 3 may be detected by a combination of the boom angle and the arm angle. This allows the posture of the front work unit 3 to be detected more accurately, and further reduces false detection of the occurrence of traveling jerkiness.

Third Embodiment
A third embodiment of the present invention will be described with reference to FIGS.

Figure 18 is a functional block diagram showing details of the state determination unit 34b of the controller 34 in the third embodiment of the present invention.

In FIG. 18, the state determination unit 34b of the controller has a state determination processing unit 34bA and a filter time constant calculation unit 34bC, and the state determination processing unit 34bA inputs the operation signals of the operation devices 52, 53 and the driving operation devices 54, 55, and the detection signals of the pressure sensors 35 to 38, and performs the above-mentioned processing explained using the flowcharts shown in FIG. 9 and FIG. 10A to FIG. 10C.

The filter time constant calculation unit 34bC estimates the magnitude (amplitude) of the vibration of the travel pedals 54b, 55b based on the pressure difference D calculated in step S4 of FIG. 10A, and determines the degree of restriction on the rate of change of the target operating pressure according to the magnitude (amplitude) of the vibration of the travel pedals 54b, 55b.

FIG. 19 is a diagram showing the relationship between the pressure difference D between the target operating pressure and the control operating pressure used to estimate the magnitude of vibration of the traveling pedals 54b, 55b and the magnitude of vibration of the traveling pedals 54b, 55b. FIG. 20 is a diagram showing the relationship between the magnitude of vibration of the traveling pedals 54b, 55b and the filter time constant τ.

The filter time constant calculation unit 34bC calculates the magnitude of vibration of the corresponding traveling pedal 54b, 55b by referring to the pressure difference D between the target operating pressure and the control operating pressure calculated in step S4 of Fig. 10A, to the relationship between the pressure difference D between the target operating pressure and the control operating pressure and the magnitude of vibration of the traveling pedals 54b, 55b shown in Fig. 19. The relationship between the pressure difference D and the magnitude of vibration of the traveling pedals 54b, 55b shown in Fig. 20 is set so that the magnitude of vibration of the traveling pedals 54b, 55b increases as the pressure difference D increases, and is stored in the controller 34.

The filter time constant calculation unit 34bC also refers to the relationship between the magnitude of vibration of the travel pedals 54b, 55b and the filter time constant τ shown in Figure 20, and calculates the corresponding filter time constant τ. The relationship between the magnitude of vibration of the travel pedals 54b, 55b and the filter time constant τ shown in Figure 21 is set so that the filter time constant τ increases as the magnitude of vibration of the travel pedals 54b, 55b increases, and is stored in the controller 34.

The filter time constant τ calculated using FIG. 20 is used in the filter process of step S19 in FIG. 10B, and the degree of restriction on the rate of change of the target operating pressure is determined according to the magnitude of vibration of the travel pedals 54b and 55b.

In this way, by determining the filter time constant τ based on the magnitude of the pressure difference D between the target operating pressure and the control operating pressure, the action of the low-pass filter can be corrected according to the magnitude (amplitude) of the vibration of the traveling pedals 54b and 55b, and the damping performance of the low-pass filter can be improved. As a result, the limiting effect on the rate of change of the target operating pressure is improved, and traveling jerkiness can be quickly suppressed.

In the second embodiment, the state determination unit 34b of the controller 34 is equipped with a pressure difference threshold determination unit 34bB, and in the second embodiment, the state determination unit 34b of the controller 34 is equipped with a filter time constant calculation unit 34bC. However, by combining the first embodiment and the second embodiment, the state determination unit 34b may be configured to include both the pressure difference threshold determination unit 34bB and the filter time constant calculation unit 34bC.

(others)
In the above embodiment, the traveling operation devices 54, 55 are of an electric type that generates an electric signal as an operation signal, but may be of a hydraulic pilot type that generates an operation pilot pressure as an operation signal. In that case, the IMU sensor detects the operation amount of the operation lever and calculates the target operation pressure in the controller 34, while the pressure sensors 35-38 detect the control operation pressure led to the traveling switching control valves 13, 14 as in the above embodiment, and the controller 34 calculates the control operation pressure and performs the same arithmetic processing as the operation signal of the electric traveling operation devices 54, 55 based on the target operation pressure and the control operation pressure. In addition, the traveling electromagnetic proportional control valves 20-23 are arranged in the oil passage that leads the operation pilot pressure to the traveling switching control valves 13, 14, and when the occurrence of traveling jerkiness is not detected, the traveling electromagnetic proportional control valves 20-23 are fully opened, and when the occurrence of traveling jerkiness is detected, the electromagnetic proportional control valves 20-23 are controlled as in the above embodiment.

1 Lower traveling body 2 Upper rotating body 3 Front working machine 1a, 1b Traveling motor 1a, 1b, 2a, 3d, 3e, 3f Multiple actuators 3a Boom 3b Arm 3c Bucket 4 Cabin 6 Hydraulic pump 13-18 Switching control valve 13, 14 Traveling switching control valve 20-31 Electromagnetic proportional control valve 20-23 Traveling electromagnetic proportional control valve 34 Controller 35, 36, 37, 38 Pressure sensor 52, 53 Operation device 52a, 53a Operation lever 54, 55 Operation device (traveling operation device)
54a, 55a Operation lever (travel operation lever, travel lever)
54b, 55b Operation pedal (travel operation pedal, travel pedal)
52c, 53c, 54c, 55c Signal generating unit X First threshold value −X Second threshold value Y1 Threshold value of travel determination time (first predetermined time)
Y2: Threshold value for the duration of the travel determination time (second predetermined time)
Z1: Threshold for determining running jerkiness (first predetermined number of times)
Z2: Threshold for determining whether or not the running jerk continues (second predetermined number of times)

Claims (10)

a plurality of actuators including a travel motor driven by pressure oil discharged from a hydraulic pump;
A plurality of switching control valves including a traveling switching control valve that controls the flow of pressure oil discharged from the hydraulic pump and supplied to the traveling motor;
A plurality of operating devices including a traveling operation device having a traveling operation lever and a traveling operation pedal located adjacent to a base end of the traveling operation lever, and generating an operation signal according to an operation amount of the traveling operation lever and the traveling operation pedal;
a controller that calculates a target operating pressure according to an operation amount based on an operation signal of the traveling operation device, generates a command current according to the target operating pressure, and, when it is determined that traveling jerkiness has occurred, corrects the target operating pressure to limit a rate of change of the target operating pressure;
A hydraulic control system for a construction machine comprising: a traveling electromagnetic proportional control valve that generates a control operating pressure according to the command current and operates the traveling switching control valve,
A pressure sensor is further provided to detect a control operating pressure generated by the traveling electromagnetic proportional control valve,
The controller
Calculating a target operating pressure according to the operation amount of the traveling operation lever and the traveling operation pedal based on the operation signal of the traveling operation device;
A hydraulic control system for a construction machine, comprising: inputting the control operating pressure detected by the pressure sensor; calculating a pressure difference between the target operating pressure and the control operating pressure; and determining whether or not the traveling jerkiness has occurred based on a change in the pressure difference. 2. The hydraulic control system for a construction machine according to claim 1,
The controller
setting a first threshold value when the pressure difference is a positive value and a second threshold value when the pressure difference is a negative value;
A hydraulic control system for a construction machine, characterized in that it determines whether the number of state changes between a first driving state in which the pressure difference is greater than a first threshold value and a second driving state in which the pressure difference is smaller than a second threshold value has reached a first predetermined number, and determines that the driving jerkiness has occurred when the number of state changes has reached the first predetermined number. 3. The hydraulic control system for a construction machine according to claim 2,
The controller
A hydraulic control system for a construction machine, characterized in that it determines whether the number of state changes reaches a first predetermined number within a first specified time, and determines that the traveling jerkiness has occurred if the number of state changes reaches the first predetermined number within the first specified time. 3. The hydraulic control system for a construction machine according to claim 2,
A hydraulic control system for a construction machine, wherein the first predetermined number of times is 1 to 3 times. 3. The hydraulic control system for a construction machine according to claim 2,
The controller
A hydraulic control system for a construction machine, characterized in that after the number of state changes reaches the first predetermined number and it is determined that the traveling jerkiness has occurred, it is further determined whether the number of state changes reaches a second predetermined number, and if the number of state changes reaches the second predetermined number, it is determined that the traveling jerkiness is continuing. 6. The hydraulic control system for a construction machine according to claim 5,
The controller
A hydraulic control system for a construction machine, characterized in that it determines whether the number of state changes has reached a second specified number within a second specified time, and if the number of state changes has reached the second specified number within the second specified time, it determines that the traveling jerkiness is continuing, and if the number of state changes has not reached the second specified number within the second specified time, it determines that the traveling jerkiness has ended. 6. The hydraulic control system for a construction machine according to claim 5,
A hydraulic control system for a construction machine, wherein the second predetermined number of times is 1 to 2 times. 3. The hydraulic control system for a construction machine according to claim 2 ,
The construction machine has an upper rotating body and a front working machine that is attached to the front part of the upper rotating body so as to be rotatable in the vertical direction and performs work.
The hydraulic control system includes an angle sensor that detects the attitude of the front work implement,
The controller
A hydraulic control system for a construction machine, characterized in that posture information of the front working machine is obtained based on the detection signal of the angle sensor, and the first threshold value and the second threshold value of the pressure difference are determined so that the absolute value becomes larger as the front working machine rotates downward and the posture of the front working machine approaches horizontal. 3. The hydraulic control system for a construction machine according to claim 2 ,
The controller
A hydraulic control system for a construction machine, characterized in that a determination is made based on the operation signal of the traveling operation device as to whether the traveling direction indicated by the operation signal is a forward direction or a reverse direction, and the first threshold value and the second threshold value of the pressure difference are determined so that their absolute values are larger when the traveling direction is the forward direction than when the traveling direction is the reverse direction. 2. The hydraulic control system for a construction machine according to claim 1,
The controller
A hydraulic control system for construction machinery, characterized in that the magnitude of vibration of the travel operation pedal is estimated based on the pressure difference, and the degree of limitation on the rate of change of the target operating pressure is determined in accordance with the magnitude of vibration of the travel operation pedal.

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