JP2019120024A - Wheel type work vehicle - Google Patents

Abstract

To provide a wheel type work vehicle which can suppress a control hunting caused by characteristics of a hydraulic system component.SOLUTION: A wheel type work vehicle comprises: a control valve 4 controlling a direction and a flow rate of a pressure oil supplied from a main hydraulic pump 2 to a travel hydraulic motor 3 on the basis of a travel operation pressure; and a control valve 6a generating the travel operation pressure inputted into the control valve 4. The work vehicle selectively switches between travel operation pressure control controlling the travel operation pressure and an engine revolution speed control controlling a revolution speed of an engine, on the basis of a difference between a target travel speed set by a cruise control setting switch 10 and an actual speed of a wheel shovel 201.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a wheeled work vehicle.

  As a technology related to automatic travel control of a construction machine, for example, Patent Document 1 discloses an engine, a hydraulic pump and a pilot pump driven by the engine, a traveling motor operated by the discharge oil of the hydraulic pump, and A control valve installed between the hydraulic pump and the traveling motor and controlling the operation of the traveling motor by switching connection of the oil path by the movement of the spool, and a pilot from the pilot pump to the spool of the control valve by the operation of the driver. The pilot pressure from the pilot pump is applied to the spool of the control valve separately from the travel pedal for controlling the operation of the control valve by applying pressure to move the spool, and the control Means to control the operation of the valve For example, the control of the control valve according to the traveling pedal having a priority over the control of said control valve by said means is disclosed.

Japanese Patent Application Laid-Open No. 10-147958

  By the way, it is considered that it is difficult to simply divert the technology of the cruise control control system of a car, because a wheel type work vehicle such as a wheeled shovel and the like differ greatly from elements constituting a travel control system from a car. In particular, the reason is that the mounting ratio of the hydraulic equipment of the wheel type work vehicle is larger than that of the automobile, as a factor. That is, for example, the main pump which is a hydraulic system component in a wheel type work vehicle, an electromagnetic proportional valve, a traveling motor, etc. have many control errors and hysteresis and can only sense the final output value, so accurate feedback control is difficult It is. Therefore, even if the technology of a cruise control control system of a car is applied to a wheeled work vehicle, control hunting or the like occurs due to the characteristics of hydraulic components, and there is a concern that each device may be broken.

  This invention is made in view of the above, and an object of the present invention is to provide a wheel type work vehicle which can control control hunting which originates in the characteristic of a hydraulic system component.

  The present application includes a plurality of means for solving the above problems, and an example thereof is an engine, a variable displacement main hydraulic pump and a pilot pump driven by the engine, and discharge from the main hydraulic pump A hydraulic hydraulic motor driven by the pressure oil, a control valve for controlling the direction and flow rate of the hydraulic oil supplied from the main hydraulic pump to the hydraulic hydraulic motor based on the input traveling operation pressure, the control In a wheeled working vehicle including a traveling pedal that generates, from pressure oil discharged from the pilot pump, a first traveling operation pressure as a candidate for traveling operation pressure input to a valve, a driver operates the wheel type vehicle. A target vehicle speed setting device for setting the target traveling speed of the work vehicle, and the traveling input to the control valve A travel operation pressure generating device for generating a second travel operation pressure separately from the first travel operation pressure as a candidate for the operation pressure, and a larger one of the first travel operation pressure and the second travel operation pressure The travel operation signal based on the difference between the target travel speed set by the target vehicle speed setting device and the actual speed of the wheeled work vehicle, and the selection valve input to the control valve as the travel operation pressure And a control device for selectively switching between traveling operation pressure control to be controlled and engine rotation number control to control the number of rotations of the engine based on the difference, wherein the control device sets the target speed more than the actual speed. If the difference between the target traveling speed and the actual speed is greater than or equal to a predetermined first threshold, the traveling operation pressure control is performed, and the difference is greater than the first threshold. If also small shall perform the engine speed control.

  According to the present invention, it is possible to suppress control hunting caused by the characteristics of hydraulic system components.

It is a side view which shows typically the appearance of the wheeled shovel which is an example of a wheel type work vehicle. It is a figure which shows typically an example of the hydraulic circuit system mounted in a wheel shovel. It is a functional block diagram showing a function concerning cruise control of a main control unit. It is a functional block diagram which shows the detail of the processing function of a throttle calculating part. It is a functional block diagram which shows the detail of the processing function of a control signal calculating part. It is a flowchart which shows the processing content which concerns on the cruise control of a main control unit. It is a figure explaining the control state in traveling operation control of cruise control, and engine number-of-rotations control. It is a figure explaining the control state in traveling operation control of cruise control and engine revolving speed control in the 2nd modification. It is a figure which shows an example of the relationship between the vehicle speed deviation and driving | running | working operation pressure in a 2nd modification.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7. In the present embodiment, a wheeled shovel is described as an example of a wheeled working vehicle, but if it is a wheeled working vehicle such as a wheel loader, for example, it has a wheel for self-propelled running. Besides the above, it is also possible to apply the present invention.

  FIG. 1 is a side view schematically showing the appearance of a wheel excavator that is an example of a wheel type working vehicle according to the present embodiment. Moreover, FIG. 2 is a figure which shows typically an example of the hydraulic circuit system mounted in a wheel shovel.

  In FIG. 1 and FIG. 2, the wheel shovel 201 includes a lower traveling body 202, an upper revolving unit 203 rotatably mounted on the upper side of the lower traveling body 202, and a front work implement 204.

  The front working tool 204 has a boom 211 rotatably coupled at its proximal end to the upper swing body 203, an arm 212 pivotally coupled to an end different from the proximal end of the boom 211, and an arm 212 The boom 211, the arm 212, and the bucket 213 are driven by hydraulic actuators, the boom cylinder 214, the arm cylinder 215, and the bucket cylinder 216, respectively. Ru.

  The lower traveling body 202 includes a front wheel 205 and a rear wheel 206, and the rear wheel 206 is driven by a variable displacement traveling hydraulic motor 3 which is a hydraulic actuator to perform a traveling operation.

  The upper revolving superstructure 203 is provided with a so-called cabin-type driver's cab 209 and an exterior cover 210 which covers most of the upper revolving superstructure 203 other than the driver's cab 209.

  Inside the exterior cover 210, the hydraulic circuit system includes the engine 1 as a prime mover, a variable displacement main hydraulic pump 2 and a pilot pump 7 driven by the engine 1, and respective hydraulic actuators from the main hydraulic pump 2 (in FIG. Control valve 4 for controlling the direction and flow rate of the hydraulic oil supplied to the traveling hydraulic motor 3 via the oil passages 4a and 4b, and control input to the control valve 4 and the regulator 2a of the main hydraulic pump 2 The signal control valve 5 etc. which switch each control pressure (a traveling operation pressure is included) which respectively concerns on the drive of a hydraulic circuit system as needed are mounted. In the present embodiment, it is assumed that traveling operation pressure is input to the control valve 4 and the regulator 2a of the main hydraulic pump 2 when the wheel excavator 201 travels, but the design of the hydraulic circuit system is assumed. It does not exclude the possibility that other control pressure may be input according to.

  Further, as a hydraulic circuit system, a traveling pedal 8 that generates a traveling operation pressure (first traveling operation pressure) input to the control valve 4 by a driver's operation, and a traveling pedal 8 input to the control valve 4 are Control valves 6a and 6b for travel operation pressure control that generate another travel operation pressure (second travel operation pressure), and the larger one of the first travel operation pressure and the second travel operation pressure The shuttle valve 9 selectively outputs the traveling operation pressure to 4 and the switching of enabling / disabling of the traveling support control (so-called cruise control) of the wheel shovel 201, the target traveling speed in cruise control (target vehicle speed VT), etc. The cruise control setting switch 10 (target vehicle speed setting device) for the driver to set, and the overall operation of the wheel shovel 201 are controlled And the main control unit 100 as a control device is provided that. The travel pedal 8 and the cruise control setting switch 10 are disposed inside the cab 209 so as to be operable by the driver.

  The control valves 6 a and 6 b of the hydraulic circuit system generate a traveling operation pressure related to cruise control based on a control signal from the main control unit 100. The control valve 6a is a travel operation pressure generation device that generates a travel operation pressure (second travel operation pressure) from the discharge pressure (pilot pressure) of the pilot pump 7 based on a control signal (CC_drive_V) from the main control unit 100. The control valve 6b is an auxiliary control valve that switches the flow / cutoff of the discharge pressure (pilot pressure) of the pilot pump 7 to the control valve 6a based on the control signal (CC_cut_V) from the main control unit 100. The control valve 6b is always switched to the flow-through side except when the main control unit 100 determines that the shutoff is necessary. Among the hydraulic circuit systems, the control valves 6a and 6b, the cruise control setting switch 10, the main control unit 100, and the like constitute a cruise control control system 100A related to the cruise control of the wheel shovel 201.

  FIG. 3 is a functional block diagram showing functions related to cruise control of the main control unit.

  In FIG. 3, the main control unit 100 is a functional unit related to cruise control, that is, a target vehicle speed setting value indicating the target traveling speed set by the cruise control setting switch 10 and a vehicle speed indicating the traveling speed (actual speed) of the wheel shovel 201 A target speed calculation unit 101 that calculates a target speed based on pulses and a vehicle speed that calculates a vehicle speed deviation that is a deviation between a target speed and an actual speed based on the target speed and the vehicle speed pulse calculated by the target speed calculation unit. Deviation calculation unit 102, control signal calculation unit 103 for calculating a control signal (CC_drive_V) of control valve 6a based on the vehicle speed deviation calculated by vehicle speed deviation calculation unit 102, traveling operation disposed downstream of shuttle valve 9 The traveling operation pressure detected by the pressure sensor 100b and the vehicle speed deviation calculated by the vehicle speed deviation calculation unit 102 A throttle calculation unit 104 is provided to calculate the throttle target opening degree of the engine 1 based on the above and to control the number of revolutions of the engine 1 by outputting to the engine control unit (ECU: Engine Control Unit) 1a .

  When the target vehicle speed setting value is input from the cruise control setting switch 10, the target speed calculation unit 101 sets transition conditions (for example, the range of the actual speed of the wheel shovel 201) predetermined as conditions that can shift to the cruise control state. It is determined whether the conditions are satisfied, and when the conditions are satisfied, the target vehicle speed setting value is calculated as the target speed. Here, the case where the signal of the target traveling speed input from the cruise control setting switch 10 also serves as a command signal for switching (starting up) cruise control effectively is illustrated. Further, the target speed calculation unit 101 stops the calculation of the target speed when the cruise control setting switch 10 is operated to cancel cruise control and a command signal to switch cruise control to ineffective (stop) is input. At the same time, the cruise control in the main control unit 100 is stopped.

  The vehicle speed deviation calculation unit 102 calculates a vehicle speed deviation that is a deviation between the actual speed and the target speed based on the target speed and the vehicle speed pulse calculated by the target speed calculation unit. Here, in the present embodiment, (vehicle speed deviation ΔV) = (target vehicle speed VT) − (actual vehicle speed VA) is defined. That is, for example, when the actual vehicle speed is slower than the target vehicle speed, the vehicle speed deviation takes a positive value, and when the actual vehicle speed is faster than the target vehicle speed, the vehicle speed deviation takes a negative value.

  FIG. 4 is a functional block diagram showing the details of the processing function of the throttle calculation unit.

  In FIG. 4, the throttle calculation unit 104 calculates a product of the vehicle speed deviation and a predetermined gain KI by using a calculation unit 104 a that outputs a product of a vehicle speed deviation that is the difference between the target vehicle speed and the actual vehicle speed and a predetermined gain KP. The first candidate for the throttle target opening degree is calculated by calculating the sum of the output of the calculation unit 104b that outputs, the integrator 104c that integrates and outputs the output of the calculation unit 104b, and the output of the calculation unit 104b and the output of the integrator 104c. The vehicle speed deviation is predetermined by the addition unit 104d as a value, the operation unit 104e which calculates a second candidate value of the throttle target opening from the traveling operation pressure using a predetermined table (Adaptive table), and the vehicle speed deviation If the threshold value is equal to or higher than the threshold value Vth, the calculation result (first candidate value) of the addition unit 104d is output to the ECU 1a as the throttle target opening degree, and in other cases (the vehicle speed deviation is smaller than the threshold value Vth) ) To have a selection unit 104f for output calculation result of the calculating section 104e (second candidate value) ECU1a as throttle target opening.

  FIG. 5 is a functional block diagram showing the details of the processing function of the control signal operation unit.

  In FIG. 5, a control signal calculation unit 103 calculates a product of a vehicle speed deviation and a predetermined gain KI, and a calculation unit 103a that outputs a product of a vehicle speed deviation that is the difference between the target vehicle speed and the actual vehicle speed and a predetermined gain KP. The control signal (CC_drive_V) of the control valve 6a is calculated by calculating the sum of the output of the calculation unit 103b and the output of the calculation unit 103b and the output of the calculation unit 103b and the output of the calculation unit 103b. When the vehicle speed deviation is greater than or equal to a predetermined threshold value Vth, the addition unit 103d takes the first candidate value of), the output storage unit 103e stores the previous output value of the control signal calculation unit 103 as the second candidate value, and Is output to the control valve 6a as the control signal (CC_drive_V) as the calculation result (first candidate value) of the addition unit 103d, and in other cases (when the vehicle speed deviation is smaller than the threshold value Vth) ) To have a selection unit 103f to be output to the control valve 6a output value of the previous stored in the output storage section 103e (the second candidate value) as the control signal (CC_drive_V).

  FIG. 6 is a flow chart showing the contents of processing relating to cruise control of the main control unit.

  In FIG. 6, first, whether or not the main control unit 100 is in the control state of cruise control, that is, it is determined by the target speed calculation unit 101 that transition to the cruise control state is possible, and cruise control is in operation. It is determined whether there is any (step S100), and when the cruise control is not in the activated state, the processing as the cruise control is ended.

  If it is determined in step S100 that the cruise control is activated, vehicle speed deviation determination is performed (step S110). If the vehicle speed deviation is equal to or greater than a predetermined threshold value Vth, travel operation pressure control is executed. If the vehicle speed deviation is smaller than the predetermined threshold value Vth, the engine speed control is executed (step S111), and the process is ended.

  As described above, the cruise control in the present embodiment controls the traveling speed of the wheel shovel 201 to follow a preset target value, and is set by the cruise control setting switch 10 (target vehicle speed setting device) By selectively switching between traveling operation pressure control for controlling the traveling operation signal and engine rotation number control for controlling the rotation number of the engine 1 based on the difference between the target traveling velocity and the actual velocity of the wheel shovel 201. is there.

  FIG. 7 is a view for explaining control states in cruise operation control of cruise control and engine rotation speed control. In the following, the case where the vehicle speed deviation ΔV is negative is also taken into consideration, and in the case of selectively switching between the traveling operation pressure control and the engine speed control based on the absolute value | ΔV | of the vehicle speed deviation and the threshold value Vth. think of.

  As shown in FIG. 7, in the present embodiment, when the absolute value of the vehicle speed deviation | ΔV | is equal to or greater than the threshold value Vth, that is, when | ΔV | VthVth, traveling operation pressure control is performed to determine the vehicle speed deviation. If the absolute value | ΔV | is smaller than the threshold value Vth, that is, if | ΔV | <Vth, engine speed control is performed.

  Here, with traveling operation control, the control valve 6a is controlled based on the control signal from the main control unit 100, and the main hydraulic pump 2 and the control valve 4 driven by the traveling operation pressure generated by the control valve 6a are Control is performed to control the vehicle speed (actual vehicle speed) to be controlled to follow a target value (target traveling speed) by controlling the rotation speed of the engine 1 based on the traveling operation pressure.

  That is, in the traveling operation pressure control, the first candidate value is selected as the control signal (CC_drive_V) of the control valve 6a in the control signal operation unit 103 of the main control unit 100, and the throttle operation unit 104 is used as the second target throttle position. Candidate values are selected and output. At this time, as shown in FIG. 7, the output PT of the control valve 6a changes so as to increase or decrease according to the increase or decrease of the vehicle speed deviation ΔV, and the engine speed NENG changes following the traveling operation pressure PA.

  Further, with engine speed control, the control valve 6a is controlled based on the control signal from the main control unit 100, and the main hydraulic pump 2 and the control valve 4 driven by the travel operation pressure generated by the control valve 6a are The vehicle speed (actual vehicle speed) to be controlled is set to the target value (target traveling speed) by controlling to maintain the state immediately before the cruise control is activated and controlling the number of rotations of the engine 1 based on the vehicle speed deviation. It is control to make it follow.

  That is, in the travel operation pressure control, the second candidate value is selected as the control signal (CC_drive_V) of the control valve 6a in the control signal calculation unit 103 of the main control unit 100, and the throttle calculation unit 104 sets the first target throttle position. Candidate values are selected and output. At this time, as shown in FIG. 7, the output PT of the control valve 6a becomes constant, and the engine speed NENG changes following the vehicle speed deviation ΔV.

  The threshold value Vth, which is the switching condition between traveling operation pressure control and engine speed control, is determined by the vehicle speed deviation when it is judged that the error of the hydraulic system component is acceptable or the vehicle speed deviation controllable by engine speed control. Do. That is, the threshold value Vth is determined by the specification of the engine, and is determined based on the range in which the vehicle speed can be controlled by the fluctuation of the engine rotational speed. For example, in a construction machine such as a wheel shovel equipped with an engine capable of changing (controlling) the engine speed in the range of 1100 rpm to 2000 rpm (for example, 19 ton class), the vehicle speed is controlled by The range of ± 2 km / h can be controlled.

  As described above, in the present embodiment, two types of control having different convergence of control amounts, that is, traveling operation pressure control and engine rotational speed control, are used. Here, in the case of the traveling operation pressure control, since the speed is controlled by driving the engine, the pump, the traveling motor, etc., there are many components to be moved at the time of control, the speed control area becomes large, and the speed deviation becomes large as a result In this case, it is possible to quickly make the actual speed follow the target speed. On the other hand, in the case of engine speed control, the component driven at the time of speed control is only the engine, so the speed control area becomes smaller compared to traveling operation pressure control, and the target speed is more accurately adjusted to the target speed when the speed deviation is small. It is possible to make As described above, cruise control control that performs more accurate feedback control can be performed by appropriately setting the conditions for state transition of the traveling operation pressure control and the engine speed control.

First Modification
In the above embodiment, the case where the traveling operation pressure control and the engine speed control are selectively switched based on the relationship between the absolute value of the vehicle speed deviation | ΔV | and one threshold value Vth has been exemplified. At this time, the threshold when the vehicle speed deviation ΔV is negative is (−Vth), and the absolute value of the threshold is the same when the vehicle speed deviation ΔV is positive and negative (that is, | Vth | = | However, different threshold values may be set depending on whether the vehicle speed deviation ΔV is positive or negative. That is, for example, the threshold (first threshold Vth1) when the vehicle speed deviation ΔV is positive and the threshold (second threshold Vth2) when negative are defined as | Vth1 | ≠ | Vth2 | The travel operation pressure control may be performed when ≦ Vth2 or Vth1 ≦ Vth1, and the engine speed control may be performed when Vth2 <ΔV <Vth1.

Second Modified Example
Further, in the above embodiment, the case where the traveling operation pressure control and the engine speed control are selectively switched based on the relationship between the absolute value of the vehicle speed deviation | ΔV | and one threshold value Vth is described as an example. However, for example, when the absolute value ΔV of the vehicle speed deviation increases (that is, when the amount of change in the vehicle speed deviation ΔV per time (d | ΔV | / dt) is positive) decreases (that is, the vehicle speed deviation ΔV The threshold value may be set for each state in which the operating characteristic of the hydraulic system component is different, such as the amount of change per hour of (when d | ΔV | / dt) is negative.

  FIG. 8 is a view for explaining control states in cruise control travel operation control and engine rotational speed control in the present modification. FIG. 9 is a diagram showing an example of the relationship between the vehicle speed deviation and the traveling operation pressure.

  In the example shown in FIG. 8, the threshold value Vth2 → 1 (the second condition under which the transition from the engine speed control to the traveling operation control is performed when the engine speed control is performed and the vehicle speed deviation is increasing) Threshold) and a threshold Vth1 → 2 (first threshold) which is a condition for transiting from the traveling operation control to the engine speed control when the traveling operation control is performed and the vehicle speed deviation decreases. It illustrates the case of definition.

  When the threshold is set in this way, control as shown in FIG. 9 is performed. That is, for example, in the case where the absolute value | ΔV | of the vehicle speed deviation increases (the range indicated by the range B), the absolute value | ΔV | of the vehicle speed deviation becomes Vth2 → 1 or more when the engine speed control is performed. When it becomes, it changes to traveling operation pressure control, and when absolute value | ΔV | of vehicle speed deviation decreases (range shown by range A), absolute value of vehicle speed deviation when traveling operation pressure control number control is performed When | ΔV | becomes smaller than Vth1 → 2, transition is made to engine speed control.

  By setting each threshold as described above, it is possible to perform control with hysteresis as in the ranges shown in the ranges C and D of FIG. 9, so it is possible to suppress control hunting more accurately.

<Third Modification>
Further, also in the second modification, different threshold values may be set for the case where the vehicle speed deviation ΔV is positive and the case where the vehicle speed deviation ΔV is negative as in the first modification. That is, when the vehicle speed deviation ΔV is positive, the threshold value Vth2 (the condition for transitioning from the engine speed control to the traveling operation control when the engine speed control is performed and the vehicle speed deviation is increasing) Two threshold values) and a threshold value Vth1 (first threshold value) which is a condition for transitioning from traveling operation control to engine rotational speed control when traveling operation control is performed and the vehicle speed deviation is decreasing. While defining, when the vehicle speed deviation ΔV is negative, a threshold value Vth4 which is a condition for transitioning from the engine speed control to the traveling operation control when the engine speed control is performed and the vehicle speed deviation decreases. (The fourth threshold) and a threshold Vth3 (the condition under which the transition from the traveling operation control to the engine speed control is made when the traveling operation control is being performed and the vehicle speed deviation is increasing) And the third threshold). As a result, control hunting can be suppressed more accurately.

  Next, the features of the above-described embodiments will be described.

  (1) In the above embodiment, the engine 1, the variable displacement main hydraulic pump 2 and the pilot pump 7 driven by the engine, and the traveling hydraulic pressure driven by the pressure oil discharged from the main hydraulic pump A motor 3, a control valve 4 for controlling the direction and flow rate of pressure oil supplied from the main hydraulic pump to the traveling hydraulic motor based on the traveling operation pressure inputted, and the traveling operation inputted to the control valve In a wheeled work vehicle (for example, a wheel shovel 201) provided with a traveling pedal 8 that generates a first traveling operation pressure as a pressure candidate from pressure oil discharged from the pilot pump, a driver operates the wheel Target vehicle speed setting device (for example, cruise control setting switch 10) for setting a target travel speed of a work vehicle And a travel operation pressure generation device (for example, control valve 6a) that generates a second travel operation pressure separately from the first travel operation pressure as a candidate for the travel operation pressure input to the control valve, and A shuttle valve 9 for inputting the larger one of the first traveling operation pressure and the second traveling operation pressure to the control valve as the traveling operation pressure, and the target traveling speed set by the target vehicle speed setting device Control for selectively switching between traveling operation pressure control that controls the traveling operation pressure based on a difference from the actual speed of the wheeled working vehicle and engine rotation number control that controls the rotation speed of the engine based on the difference A device (e.g., main control unit 100), wherein the control device is configured to drive the target travel speed when the target travel speed is greater than the actual speed. When the difference obtained by subtracting the actual speed is equal to or greater than a predetermined first threshold, the traveling operation pressure control is performed, and when the difference is smaller than the first threshold, the engine speed control is performed. Was supposed to

  Thus, control hunting caused by the characteristics of hydraulic system components can be suppressed.

  (2) Further, in the above-described embodiment, in the wheeled working vehicle according to (1), the control device determines that the absolute value of the difference between the target traveling speed and the actual speed is greater than or equal to the first threshold. In the present embodiment, the traveling operation pressure control is performed, and the engine speed control is performed when the absolute value of the difference is smaller than the first threshold.

  (3) In the above embodiment, in the wheeled working vehicle according to (1), the control device determines the actual speed from the target traveling speed when the target traveling speed is smaller than the actual speed. The engine speed control is performed when the difference when the difference is subtracted is larger than a second predetermined threshold so as to be smaller than the first threshold, and when the difference is smaller than the second threshold. The travel operation pressure control is performed.

  (4) In the above embodiment, in the wheeled work vehicle according to (1), the control device is configured to determine the number of engine revolutions when the absolute value of the difference is smaller than the first threshold. When transitioning to control and performing the engine rotational speed control, and when the absolute value of the difference is smaller than a second threshold set to a value larger than the first threshold, the engine rotational speed When the control is performed and the engine speed control is performed, and when the absolute value of the difference increases, and when the absolute value of the difference becomes equal to or more than the second threshold value, When transitioning to traveling operation pressure control and the traveling operation pressure control is performed, and when the absolute value of the difference is equal to or more than the first threshold, the traveling operation pressure control is performed.

  (5) Further, in the above-described embodiment, in the wheeled working vehicle according to (1), when the target traveling speed is larger than the actual speed, the control device determines that the difference is the first threshold. If the target traveling speed is larger than the actual speed, and if the engine rotational speed control is being performed, the difference is less than the actual speed. If it is smaller than a second threshold set to a value larger than one threshold, the engine speed control is performed, and if the target traveling speed is larger than the actual speed, the engine speed control is performed. If the difference is increased, and if the difference is greater than or equal to the second threshold value, the process transits to the travel operation pressure control, and the target travel speed is higher than the actual speed. Is large If the traveling operation pressure control is being performed, and if the difference is greater than or equal to the first threshold, the traveling operation pressure control is performed, and the target traveling speed is smaller than the actual speed. And when the difference becomes larger than a predetermined third threshold value, the engine speed control is performed, and when the target travel speed is smaller than the actual speed, the engine speed If the control is being performed, and if the difference is larger than a fourth threshold set to a value smaller than the third threshold, the engine speed control is performed, and the target travel is made than the actual speed. When the speed is low, and when the engine speed control is being performed, and when the difference is increasing, and when the difference is less than or equal to the fourth threshold, the travel operation pressure Transition to control When the target travel speed is lower than the actual speed, and when the travel operation pressure control is performed, and when the difference is less than the third threshold, the travel operation pressure control is performed. It was a thing.

<Supplementary Note>
The present invention is not limited to the above embodiments, and includes various modifications and combinations within the scope not departing from the gist of the present invention. Further, the present invention is not limited to the one provided with all the configurations described in the above embodiment, but also includes one in which a part of the configuration is deleted. In addition, each of the configurations, functions, and the like described above may be realized by designing a part or all of them with, for example, an integrated circuit. Further, each configuration, function, etc. described above may be realized by software by the processor interpreting and executing a program that realizes each function.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Engine control unit (ECU), 2 ... Main hydraulic pump, 2a ... Regulator, 3 ... Traveling hydraulic motor, 4 ... Control valve, 4a, 4b ... Oil path, 5 ... Signal control valve, 6a, 6b ... Control valve, 7 ... Pilot pump, 8 ... Travel pedal, 9 ... Shuttle valve, 10 ... Cruise control setting switch, 100 ... Main control unit, 100A ... Cruise control system, 100b ... Travel operation pressure sensor, 101 ... Target speed Calculation unit 102: vehicle speed deviation calculation unit 103: control signal calculation unit 103a: calculation unit 103b: calculation unit 103c: integrator 103d: addition unit 103e: output storage unit 103f: selection unit 104: Throttle operation unit, 104a ... operation unit, 104b ... operation unit, 104c ... integrator 04 d ... addition unit, 104 e ... operation unit, 104 f ... selection unit, 201 ... wheel excavator, 202 ... lower traveling body, 203 ... upper swing body, 204 ... front work machine, 205 ... front wheel, 206 ... rear wheel, 209 ... driving Chamber, 210: Exterior cover, 211: Boom, 212: Arm, 213: Bucket, 214: Boom cylinder, 215: Arm cylinder, 216: Bucket cylinder

Claims (5)

With the engine,
A variable displacement main hydraulic pump and a pilot pump driven by the engine;
A traveling hydraulic motor driven by pressure oil discharged from the main hydraulic pump;
A control valve that controls the direction and flow rate of pressure oil supplied from the main hydraulic pump to the traveling hydraulic motor based on the traveling operation pressure that is input;
A wheeled working vehicle comprising: a travel pedal generating a first travel operation pressure as a candidate for travel operation pressure input to the control valve from pressure oil discharged from the pilot pump;
A target vehicle speed setting device for setting a target traveling speed of the wheeled working vehicle by a driver;
A traveling operation pressure generation device that generates a second traveling operation pressure separately from the first traveling operation pressure as a candidate for the traveling operation pressure input to the control valve;
A shuttle valve for inputting the larger one of the first traveling operation pressure and the second traveling operation pressure to the control valve as the traveling operation pressure;
The traveling operation pressure control for controlling the traveling operation pressure based on the difference between the target traveling speed set by the target vehicle speed setting device and the actual speed of the wheeled working vehicle, and the number of rotations of the engine based on the difference A control device that selectively switches between engine speed control and
The control device is configured to drive the vehicle when the target traveling speed is greater than the actual speed, and the difference obtained by subtracting the actual speed from the target traveling speed is equal to or greater than a predetermined first threshold. An operating pressure control is performed, and the engine speed control is performed when the difference is smaller than the first threshold value. In the wheel type work vehicle according to claim 1,
The control device performs the traveling operation pressure control when the absolute value of the difference between the target traveling speed and the actual speed is greater than or equal to the first threshold, and the absolute value of the difference is greater than the first threshold A wheel type working vehicle characterized by performing said engine speed control, when smaller. In the wheel type work vehicle according to claim 1,
When the target traveling speed is smaller than the actual speed, the control device may further include a second predetermined second difference such that the difference between the target traveling speed and the actual speed is smaller than the first threshold. A wheel type work vehicle characterized by performing said engine speed control, when larger than a threshold, and performing said traveling operation pressure control, when said difference is below the second threshold. In the wheel type work vehicle according to claim 1,
The controller is
When the absolute value of the difference becomes smaller than the first threshold value, transition to the engine speed control is made,
When the engine speed control is performed, and the absolute value of the difference is smaller than a second threshold set to a value larger than the first threshold, the engine speed control is performed.
When the engine speed control is performed, and when the absolute value of the difference increases, and when the absolute value of the difference becomes equal to or greater than the second threshold, the travel operation pressure control Transition to
A wheel type work vehicle characterized by performing said traveling operation pressure control, when said traveling operation pressure control is performed, and when the absolute value of said difference is more than said 1st threshold. In the wheel type work vehicle according to claim 1,
The controller is
When the target traveling speed is larger than the actual speed, and when the difference becomes smaller than the first threshold value, transition to the engine speed control is made,
When the target traveling speed is higher than the actual speed, and when the engine speed control is performed, the difference is smaller than a second threshold set to a value larger than the first threshold. In the case, the engine speed control is performed.
When the target traveling speed is larger than the actual speed, and when the engine speed control is performed, and when the difference is increasing, the difference is equal to or more than the second threshold. If it does, the transition to the travel operation pressure control is made,
When the target travel speed is larger than the actual speed, and when the travel operation pressure control is performed, and when the difference is equal to or more than the first threshold, the travel operation pressure control is performed.
When the target traveling speed is smaller than the actual speed, and when the difference becomes larger than a predetermined third threshold, transition is made to the engine speed control.
When the target traveling speed is lower than the actual speed, and when the engine speed control is performed, the difference is larger than a fourth threshold set to a value smaller than the third threshold. In the case, the engine speed control is performed.
When the target traveling speed is smaller than the actual speed, and when the engine speed control is performed, and when the difference is increasing, the difference is less than or equal to the fourth threshold. If it does, the transition to the travel operation pressure control is made,
If the target travel speed is smaller than the actual speed, and if the travel operation pressure control is being performed, and if the difference is less than or equal to the third threshold value, the travel operation pressure control is to be performed. Wheel-type work vehicle that features.

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