JP2014185665A - Travel control device for wheel type work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce or prevent a dash-out phenomenon of a work vehicle during travelling caused by operation other than the travelling.SOLUTION: A travel control device for a wheel type work vehicle includes valve control means 120 and 162 for controlling a flow control valve 161 in accordance with a traveling operation amount detected by traveling operation amount detecting means 171, a working operation amount detected by working operation amount detecting means 172, and a discharge pressure of a hydraulic pump 130 detected by discharge pressure detecting means 173. The valve control means 120 and 162 control a flow rate of pressure oil to be supplied to a traveling motor 115 so as to prevent a dash-out phenomenon of the wheel type work vehicle when an operation state is shifted from a traveling single operation state in which a traveling operation member 155 is operated and working operation members 156 and 157 are not operated to a composite operation state in which the traveling operation member 155 is operated and the working operation members 156 and 157 are operated.

Description

  The present invention relates to a travel control device for a wheeled work vehicle such as a wheeled hydraulic excavator.

  There is a wheel type hydraulic excavator as a wheel type work vehicle. The wheel-type hydraulic excavator is a front work having a four-wheel wheel-type traveling body, a revolving body provided on the traveling body so as to be able to swivel, and a boom, an arm and a bucket provided substantially at the front of the revolving body. Device.

  The wheel-type hydraulic excavator is provided with a traveling motor for driving the traveling body and a hydraulic actuator for driving the front working device. The flow of pressure oil supplied from the hydraulic pump to the traveling motor is controlled by the traveling direction control valve, and the flow of pressure oil supplied from the hydraulic pump to the hydraulic actuator for the front working device is controlled by the working direction control valve. Is done.

  Conventionally, there is known a wheeled working vehicle in which a traveling direction control valve and a working direction control valve are provided on a center bypass line and connected in parallel to a hydraulic pump (Patent Document 1).

JP 2002-130003 A

  In a wheel-type hydraulic excavator, the driving pressure of a traveling motor (hereinafter referred to as “traveling driving pressure”) is lower than the driving pressure of a hydraulic actuator, particularly a boom cylinder, which is a driving source for operations for work. For this reason, as in the technique described in Patent Document 1, the traveling direction control valve and the working direction control valve are provided on the center bypass line and connected in parallel to the hydraulic pump. When the boom is raised during low speed or low speed traveling with a relatively low pressure, the discharge pressure of the hydraulic pump acts on the traveling motor on the lower pressure side than the boom cylinder on the higher pressure side. As a result, the pressure oil flowing into the traveling motor increases rapidly, that is, the traveling speed rapidly increases, and a phenomenon occurs in which the wheel-type hydraulic excavator travels (hereinafter referred to as “pop-out phenomenon”). This pop-out phenomenon is an unpleasant phenomenon for an operator traveling at a low speed or a low speed.

The travel control device for a wheeled work vehicle according to claim 1 is driven by a hydraulic pump driven by an engine, a travel motor driven by pressure oil discharged from the hydraulic pump, and pressure oil from the hydraulic pump. An operating device actuator for driving the front operating device, a traveling direction control valve for controlling a flow of pressure oil supplied from the hydraulic pump to the traveling motor, and a hydraulic pump provided in the center bypass line of the hydraulic pump. A directional control valve for the working device that controls the flow of pressure oil supplied to the actuator for the working device and a flow rate of the pressure oil that is provided upstream of the traveling directional control valve and that is supplied from the hydraulic pump to the traveling motor. A flow control valve for operating, a travel operation member for operating the travel motor, a work operation member for operating the actuator for the work device, and a travel operation member Detected by the travel operation amount detection means for detecting the operation amount, the work operation amount detection means for detecting the operation amount of the work operation member, the discharge pressure detection means for detecting the discharge pressure of the hydraulic pump, and the travel operation amount detection means. And a valve control means for controlling the flow rate control valve according to the travel operation amount detected by the work operation amount detection means and the discharge pressure of the hydraulic pump detected by the discharge pressure detection means. The valve control means changes from a traveling single operation state in which the traveling operation member is operated and the work operation member is not operated to a combined operation state in which the traveling operation member is operated and the work operation member is operated. In this case, the flow rate of the pressure oil supplied to the traveling motor is controlled so as to suppress the pop-out phenomenon of the wheel type work vehicle.
The travel control device for a wheeled work vehicle according to claim 2 is the travel control device for a wheeled work vehicle according to claim 1, wherein motor pressure detection means for detecting the pressure of pressure oil supplied to the travel motor is provided. In addition, the valve control means controls the flow control valve in consideration of the pressure detected by the motor pressure detection means.
The travel control device for a wheeled work vehicle according to claim 3 is the travel control device for a wheeled work vehicle according to claim 1 or 2, wherein the valve control means is changed from a traveling single operation state to a combined operation state. When the flow control valve is controlled so that the opening area of the flow control valve is smaller than that in the traveling single operation state, the popping phenomenon of the wheel type work vehicle is suppressed.
The travel control device for a wheeled work vehicle according to claim 4 is the travel control device for a wheeled work vehicle according to any one of claims 1 to 3, wherein the travel operation amount detecting means travels a predetermined value or more. When the operation amount is detected and a work operation amount greater than or equal to a predetermined value is detected by the work operation amount detection means, the condition determination means for determining that the flow restriction condition is satisfied, and the flow restriction condition is determined by the condition determination means. When it is determined that the flow rate control valve is established, it is effective to control the flow rate control valve by the valve control unit. When the condition determination unit determines that the flow rate restriction condition is not satisfied, the valve control unit sets the flow rate control valve. It is characterized by comprising validating / invalidating means for invalidating the control.
The travel control device for a wheeled work vehicle according to claim 5 is the travel control device for a wheeled work vehicle according to any one of claims 1 to 3, wherein the rotation of the travel motor is decelerated and transmitted to the wheels. A speed reduction mechanism capable of changing the speed reduction ratio, and a speed reduction ratio detection means for detecting the speed reduction ratio of the speed reduction mechanism, the travel operation amount detection means detecting a travel operation amount greater than a predetermined value, and a work operation amount A condition determining unit that determines that the flow rate restriction condition is satisfied when a work operation amount greater than or equal to a predetermined value is detected by the detecting unit and a reduction ratio that is greater than or equal to the predetermined value is detected by the reduction ratio detecting unit; Therefore, when it is determined that the flow restriction condition is satisfied, it is effective to control the flow control valve by the valve control means, and when the flow restriction condition is determined not to be satisfied by the condition determination means. , Characterized in that it includes a valid / invalid means for disabling to control the flow control valve by the valve control means.

  ADVANTAGE OF THE INVENTION According to this invention, the jumping-out phenomenon of driving | running | working accompanying the working vehicle in driving | running | working operations other than driving | running | working can be reduced or prevented. Thereby, a comfortable ride can be provided to the operator of the wheel type work vehicle.

The side view which shows the wheel shovel to which the traveling control apparatus by this invention is applied. The figure which shows schematic structure of the traveling control apparatus which concerns on 1st Embodiment. The block diagram which shows the structure of the traveling control apparatus which concerns on 1st Embodiment. The figure which shows the characteristic used by each calculating part of FIG. The block diagram which shows the structure of the traveling control apparatus which concerns on 2nd Embodiment. The figure which shows schematic structure of the traveling control apparatus which concerns on 3rd Embodiment. The block diagram which shows the structure of the traveling control apparatus which concerns on 3rd Embodiment. The figure which shows the characteristic used by the 4th calculating part of FIG.

Hereinafter, an embodiment of a wheeled work vehicle to which a travel control device according to the present invention is applied will be described with reference to the drawings.
-First embodiment-
FIG. 1 is a side view of a wheeled hydraulic excavator (hereinafter referred to as a wheel excavator 100) as an example of a wheeled work vehicle according to the present embodiment. For convenience of explanation, the front-rear and up-down directions are defined as shown in FIG.

  The wheel excavator 100 includes a traveling body 101 and a revolving body 102 mounted on the traveling body 101 so as to be able to swivel. The traveling body 101 is mounted with a traveling hydraulic motor (hereinafter referred to as a traveling motor), and the wheels 105 are rotated by driving the traveling motor. The swivel body 102 is provided with a cab 104 and a front work device 110. A counterweight 109 is attached to the rear part of the revolving unit 102 to balance the machine body during work.

  The front work device 110 includes a boom 106, an arm 107, and a bucket 108. The boom 106 and the arm 107 are driven and raised by the boom cylinder 116 and the arm cylinder 117, respectively. The bucket 108 is attached to the tip of the arm 107 so as to be rotatable in the vertical direction with respect to the arm 107 and is driven by a bucket cylinder 118.

  FIG. 2 is a diagram illustrating a schematic configuration of the travel control device. Pressure oil from the main pump 130 driven by the engine 190 is supplied to the travel motor 115, the boom cylinder 116, and the arm cylinder 117 via the valve unit 140, and the travel motor 115, the boom cylinder 116, and the The arm cylinder 117 is driven.

  The valve unit 140 is an open center travel direction control valve 145, a boom direction control valve 146, and an arm direction that control the flow of pressure oil supplied to the travel motor 115, the boom cylinder 116, and the arm cylinder 117, respectively. A control valve 147 and a variable throttle 161 having a variable opening area through which pressure oil flows are provided. Each direction control valve 145, 146, 147 is provided in a center bypass line 191 that connects the main pump 130 and the tank 199. In other words, the traveling direction control valve 145, the boom direction control valve 146, and the arm direction control valve 147 are connected in tandem to the center bypass line 191.

  The directional control valves 145, 146, 147 are connected in parallel by a parallel oil passage 192 branched from a center bypass line 191 upstream of the traveling directional control valve 145. A variable throttle 161 is provided in a feeder oil passage 193 branched from the parallel oil passage 192 and connected to the traveling direction control valve 145. The variable throttle 161 controls the flow rate of pressure oil supplied to the travel motor 115. The variable throttle 161 is displaced between a position (A) where the opening area through which the pressure oil flows is the maximum area (A) and a position (B) where the opening area through which the pressure oil flows is reduced to the minimum area.

  The variable throttle 161 operates between the (A) position and the (B) position by the electromagnetic proportional valve 162 that operates according to a control signal from the controller 120. That is, the operation of the variable throttle 161 is controlled by the electromagnetic proportional valve 162 and the controller 120.

  The electromagnetic proportional valve 162 is provided in a pilot line that connects the pilot pump 131 driven by the engine 190 and the pilot portion of the variable throttle 161. The electromagnetic proportional valve 162 is displaced between a position (A) where the pressure oil from the pilot pump 131 is supplied to the pilot section of the variable throttle 161 and a position (B) where the pressure oil from the pilot pump 131 is shut off. As the current value input to the solenoid of the solenoid proportional valve 162 increases, the amount of displacement from the position (B) to the position (A) increases, and when no current is supplied to the solenoid, the return spring returns the position (B). Can be switched.

  Pressure oil from the pilot pump 131 is supplied to pilot valves provided in each of the travel operation pedal 155, the boom operation lever 156, and the arm operation lever 157. When each operating member 155, 156, 157 is operated, a pilot secondary pressure is generated by each pilot valve. The pilot secondary pressure generated in each pilot valve acts on the pilot ports of the traveling direction control valve 145, the boom direction control valve 146, and the arm direction control valve 147. Therefore, the spools of the direction control valves 145, 146, 147 corresponding to the operated operation members 155, 156, 157 are driven according to the operation amounts of the operation members 155, 156, 157.

  In the present embodiment, the opening degree of the travel direction control valve 145 is controlled according to the operation amount of the travel operation pedal 155, and the greater the operation amount of the travel operation pedal 155, the greater the amount supplied to the travel motor 115. The flow rate of the pressure oil increases, and the rotational speed of the traveling motor 115 increases.

  The wheel excavator 100 includes a transmission 150 that can change a reduction gear ratio. The rotation of the travel motor 115 is decelerated by the transmission 150 and then transmitted to the wheels 105 via an axle (not shown) and an axle (not shown), and the wheel excavator 100 travels.

  The transmission 150 is a well-known one having a planetary reduction mechanism including a sun gear, a planetary gear, and a ring gear (not shown), and clutches 150a and 150b provided on the sun gear side and the ring gear side, respectively. Although not shown, each of the clutches 150a and 150b has a clutch cylinder with a built-in spring, and the clutch cylinder 150a and 150b are brought into an engaged state when the clutch cylinder is pressed against the disk by the urging force of the spring. Is done. The clutch 150a and 150b are released by removing the pressing force of the clutch cylinder by the hydraulic pressure from the pilot pump 131 acting against the spring force. The oil pressure acting on the clutches 150a and 150b is controlled by driving the electromagnetic switching valve 151. A clutch that is engaged by the urging force of the spring and released by the hydraulic pressure is referred to as a negative clutch.

  The electromagnetic switching valve 151 is switched by a control signal output from the controller 120 according to the operation of the shift switch 158. When the electromagnetic switching valve 151 is switched to the position (A), the pressure oil from the pilot pump 131 acts on the clutch 150a. As a result, the clutch 150a is disengaged and the clutch 150b is engaged, and the transmission 150 is set to a predetermined gear ratio R1 (low gear), so that low-speed and high-torque first-speed running is possible.

  When the electromagnetic switching valve 151 is switched to the position (B), the pressure oil from the pilot pump 131 acts on the clutch 150b. As a result, the clutch 150b is disengaged and the clutch 150a is engaged, and the transmission 150 has a predetermined gear ratio R2 (high gear), enabling high-speed and low-torque 2-speed traveling. The gear ratio R1 is larger than the gear ratio R2.

  When the electromagnetic switching valve 151 is switched to the position (C), the clutches 150a and 150b communicate with the tank 199. In this case, since the clutch 150a and the clutch 150b are engaged by the spring force, the transmission 150 is locked and rotation of the axle is prevented.

  The controller 120 includes an arithmetic processing unit having a CPU and a storage device such as ROM and RAM, and other peripheral circuits, and controls the entire system of the wheel excavator 100.

  The controller 120 includes a pressure sensor 172 for detecting the larger one of the operation amounts of the boom operation lever 156 and the arm operation lever 157 and a detection amount of the travel operation pedal 155. A pressure sensor 171, a shift switch 158, and a pressure sensor 173 that detects the discharge pressure of the main pump 130 are connected.

  A plurality of high pressure selection valves 196, 197, 198 are arranged between the pressure sensor 172, the boom operation lever 156 and the arm operation lever 157, and the pilot valves of the boom operation lever 156 and the arm operation lever 157, respectively. The highest pressure among the pilot secondary pressures output from is detected by the pressure sensor 172.

  A high pressure selection valve 195 is disposed between the pressure sensor 171 and the travel operation pedal 155, and among the pilot secondary pressure as a forward or reverse instruction signal output from the pilot valve of the travel operation pedal 155. A high pressure is detected by the pressure sensor 171.

  The shift switch 158 is an operation switch for shifting the transmission 150 to the first speed with a large reduction ratio or the second speed with a small reduction ratio. The shift switch 158 outputs to the controller 120 a signal for setting the transmission 150 to the low gear when operated at the first speed. When the controller 120 detects that the shift switch 158 is operated to the first speed, the controller 120 outputs a control signal for switching the electromagnetic switching valve 151 to the position (A). The shift switch 158 outputs a signal to the controller 120 for setting the transmission 150 to the high gear when operated at the second speed. When the controller 120 detects that the shift switch 158 is operated to the second speed, the controller 120 outputs a control signal for switching the electromagnetic switching valve 151 to the position (B).

  FIG. 3 is a block diagram showing the configuration of the travel control apparatus according to the first embodiment. FIG. 4 is a diagram showing characteristics used in the respective arithmetic units shown in FIG. The controller 120 calculates the opening area Ad of the variable throttle 161 from the pressure Pd detected by the pressure sensor 172, and the first calculation unit 123 that calculates the opening area Ad of the variable throttle 161 from the pressure Pd detected by the pressure sensor 171. And a third calculation unit 125 that calculates the opening area Ap of the variable throttle 161 from the pressure Pp detected by the pressure sensor 173.

  In the first calculation unit 123, a variable throttle that monotonously increases as the detection value Pd of the pressure sensor 171 (hereinafter also referred to as traveling operation pressure) Pd increases based on a predetermined characteristic f1 shown in FIG. The aperture area Ad of 161 is calculated. As shown in FIG. 4A, according to the characteristic f1, when the detected value Pd is equal to or smaller than the predetermined value Pd1, the opening area Ad is the minimum value Amin, and the detected value Pd is within the range from Pd1 to Pd2. As the aperture increases, the opening area Ad increases exponentially from the minimum value Amin to the maximum value Amax. According to the characteristic f1, when the detection value Pd is equal to or greater than the predetermined value Pd2, the opening area Ad becomes the maximum value Amax.

  In the second calculation unit 124, a variable diaphragm that monotonously decreases as the detection value Pf of the pressure sensor 172 (hereinafter also referred to as front operating pressure) Pf increases based on a predetermined characteristic f2 shown in FIG. The aperture area Af of 161 is calculated. As shown in FIG. 4B, according to the characteristic f2, when the detected value Pf is equal to or smaller than the predetermined value Pf1, the opening area Af is the maximum value Amax, and the detected value Pf is within the range of Pf1 to Pf2 As the distance increases, the opening area Af decreases exponentially from the maximum value Amax to the minimum value Amin. According to the characteristic f2, the opening area Af becomes the minimum value Amin when the detection value Pf is equal to or greater than the predetermined value Pf2.

  In the third calculation unit 125, a variable throttle that monotonously decreases as the detection value Pp of the pressure sensor 173 (hereinafter also referred to as pump discharge pressure) Pp increases based on a predetermined characteristic f3 shown in FIG. The aperture area Ap of 161 is calculated. As shown in FIG. 4C, according to the characteristic f3, when the detected value Pp is equal to or smaller than the predetermined value Pp1, the opening area Ap is the maximum value Amax, and the detected value Pp is within the range from Pp1 to Pp2. As the value increases, the opening area Ap decreases exponentially from the maximum value Amax to the minimum value Amin. According to the characteristic f3, when the detection value Pp is equal to or greater than the predetermined value Pp2, the opening area Ap becomes the minimum value Amin.

  As shown in FIG. 3, the controller 120 functionally includes a maximum value selection unit 126 and a minimum value selection unit 127. The maximum value selection unit 126 compares the opening area Ad calculated by the first calculation unit 123 with the opening area Af calculated by the second calculation unit 124, and determines which one of the opening area Ad and the opening area Af. The larger one is selected as the first opening area A1.

  The minimum value selection unit 127 compares the first opening area A1 selected by the maximum value selection unit 126 with the opening area Ap calculated by the third calculation unit 125, and compares the first opening area A1 and the opening area Ap. The smaller one of these is selected as the target opening area At.

  The controller 120 uses the traveling operation determination unit 121 that determines whether or not the traveling operation pedal 155 is operated based on the pressure Pd detected by the pressure sensor 171 and the work operation based on the pressure Pf detected by the pressure sensor 172. It is determined whether or not the flow restriction condition is satisfied based on the determination result of the work operation determination unit 122 that determines whether or not the operation levers 156 and 157 are operated, and the travel operation determination unit 121 and the work operation determination unit 122. A condition determination unit 180 is functionally provided. The controller 120 further functionally includes a maximum value setting unit 182 that sets the target opening area At to the maximum value Amax, and a switch unit 181 that is switched based on the determination result of the condition determination unit 180.

  The traveling operation determination unit 121 determines whether or not the pressure Pd detected by the pressure sensor 171 is greater than or equal to the threshold value Pt1. The threshold value Pt1 is a threshold value used for determining whether or not a traveling operation is being performed. The threshold value Pt1 is set in consideration of the pilot secondary pressure at which the wheel excavator 100 starts traveling in the pilot secondary pressure generated by the pilot valve of the traveling operation pedal 155. The traveling operation determination unit 121 determines that the traveling operation is not performed when the pressure Pd detected by the pressure sensor 171 is less than the threshold value Pt1, and when the pressure Pd detected by the pressure sensor 171 is greater than or equal to the threshold value Pt1. It is determined that a traveling operation is being performed.

  The work operation determination unit 122 determines whether or not the pressure Pf detected by the pressure sensor 172 is greater than or equal to the threshold value Pt2. The threshold value Pt2 is stored in advance in the storage device. The threshold value Pt2 is a threshold value used for determining whether or not the front work apparatus 110 is being operated. The threshold value Pt2 is set in consideration of the pilot secondary pressure at which the front working device 110 starts to drive among the pilot secondary pressures generated by the pilot valves of the work operation levers 156 and 157. The work operation determination unit 122 determines that a work operation is not performed when the pressure Pf detected by the pressure sensor 172 is less than the threshold value Pt2, and when the pressure Pf detected by the pressure sensor 172 is greater than or equal to the threshold value Pt2. It is determined that a work operation is being performed.

  The condition determination unit 180 determines, based on signals from the work operation determination unit 122 and the travel operation determination unit 121, whether a work operation is performed and a travel operation is performed, that is, whether a composite operation is performed. To do. When the condition determination unit 180 determines that the composite operation is performed, the condition determination unit 180 determines that the flow restriction condition is satisfied, and outputs an ON signal to the switch unit 181. When the ON signal is input, the switch unit 181 is switched to the terminal (A) side. When the condition determination unit 180 determines that the work operation is not performed or the traveling operation is not performed based on the signals from the work operation determination unit 122 and the travel operation determination unit 121, the flow restriction condition is satisfied. It is determined that it is not, and an off signal is output to the switch unit 181. When an off signal is input, the switch unit 181 switches to the terminal (B) side.

  The controller 120 switches the target opening area At selected by the minimum value selection unit 127 output via the switch unit 181 when the flow restriction condition is satisfied, or the switch when the flow restriction condition is not established. A control pressure calculation unit 128 that calculates the control pressure Pv of the electromagnetic proportional valve 162 according to the target opening area At set by the maximum value setting unit 182 output via the unit 181 is functionally provided.

  The control pressure calculation unit 128 calculates a control pressure Pv corresponding to the target opening area At based on a predetermined characteristic f4 shown in FIG. As shown in FIG. 4D, according to the characteristic f4, the control pressure Pv increases exponentially from the minimum value Pvmin to the maximum value Pvmax as the target opening area At increases in the range of the target opening area At from Amin to Amax. To increase.

  The controller 120 functionally includes a current calculation unit 129 that calculates a control current I output to the electromagnetic proportional valve 162 according to the control pressure Pv of the electromagnetic proportional valve 162 calculated by the control pressure calculation unit 128.

  The current calculation unit 129 calculates a control current I corresponding to the control pressure Pv based on a predetermined characteristic f5 shown in FIG. As shown in FIG. 4E, according to the characteristic f5, the control current I increases exponentially from the minimum value Imin = 0 to the maximum value Imax as the control pressure Pv increases in the range of the control pressure Pv from Pvmin to Pvmax. To increase.

  When the switch unit 181 is switched to the position (A), the controller 120 outputs the control current I calculated by the current calculation unit 129 to the electromagnetic proportional valve 162 so that the opening area of the variable throttle 161 is the minimum value. The variable diaphragm 161 is controlled so that the opening area selected by the selection unit 127 is obtained.

  In the controller 120, the travel operation pedal 155 is operated and the boom operation lever 156 or the arm is operated from the travel single operation state in which the travel operation pedal 155 is operated and the boom operation lever 156 and the arm operation lever 157 are not operated. When the operation lever 157 is operated in the combined operation state, the variable aperture 161 is controlled so that the opening area of the variable aperture 161 becomes smaller than that in the traveling single operation state, so that the wheel shovel 100 pops out. Reduce or prevent.

The main operation of the travel control device for the wheel excavator 100 according to the first embodiment will be described.
When the boom operation lever 156 and the arm operation lever 157 are not operated, the front operation pressure Pf is equal to or less than Pf1. For this reason, the work operation determination unit 122 of the controller 120 determines that the work operation is not performed. In a state where the travel operation pedal 155 is not operated, the travel operation pressure Pd is equal to or less than Pd1. For this reason, the traveling operation determination unit 121 of the controller 120 determines that the traveling operation is not performed. The condition determination unit 180 determines that the flow restriction condition is not satisfied based on the determination results of the work operation determination unit 122 and the travel operation determination unit 121.

  In a state where the flow restriction condition is not satisfied, the controller 120 switches the switch unit 181 to the position (B), blocks between the minimum value selection unit 127 and the control pressure calculation unit 128, and sets the target opening of the variable throttle 161. The area At is set to the maximum value Amax. The controller 120 performs a process of outputting the control current I = Imax to the solenoid of the electromagnetic proportional valve 162. As a result, the electromagnetic proportional valve 162 is switched to the position (A), and the variable throttle 161 is switched to the position (A).

  When the traveling operation pedal 155 is finely operated from such a non-operating state, the spool of the traveling direction control valve 145 moves according to the operation amount of the traveling operation pedal 155, and the pressure oil discharged from the main pump 130 travels. It is supplied to the traveling motor 115 via the direction control valve 145. When pressure oil is supplied to the travel motor 115, the travel motor 115 is driven to rotate, and the wheel excavator 100 travels.

  In the traveling single operation state in which the front work operation is not performed, the work operation determination unit 122 determines that the work operation is not performed. Accordingly, the condition determination unit 180 determines that the flow restriction condition is not satisfied, and thus the variable throttle 161 is maintained at the position (A).

  When traveling at a low speed, for example, when the operator operates the boom operation lever 156 to the up side, the operation of the boom operation lever 156 is detected by the pressure sensor 171 and input to the controller 120. The work operation determination unit 122 determines that a front work operation is being performed, and the traveling operation determination unit 121 determines that a traveling operation is being performed. Thereby, the condition determination unit 180 determines that the flow restriction condition is satisfied.

  When it is determined that the flow restriction condition is satisfied, the switch unit 181 is switched to the position (A) where the minimum value selection unit 127 and the control pressure calculation unit 128 are connected, and the opening selected by the minimum value selection unit 127 The area is input to the control pressure calculation unit 128 as the target opening area At.

  When traveling at a low speed, the opening area calculated according to the operation amount of the operation levers 156 and 157 for work and the opening area calculated according to the pump discharge pressure Pp is smaller. Thus, the variable throttle 161 is controlled so that the flow rate of the pressure oil supplied to the traveling motor 115 is throttled.

For example,
(Α) When both the travel operation pressure Pd and the front operation pressure Pf are low (for example, Pd ≦ Pd1, Pf ≦ Pf1) and the pump discharge pressure Pp is high (for example, Pp ≧ Pp2), the variable throttle 161 switches to position (B). In a boom raising operation or the like in which heavy objects such as earth and sand are loaded on the bucket 108, the pump discharge pressure Pp becomes high, and the wheel shovel 100 jumps out easily. In the present embodiment, even if the amount of operation of the front working device is small, the flow rate of the pressure oil supplied to the traveling motor 115 by the variable throttle 161 is limited if the pump discharge pressure Pp is high.
(Β) When the travel operation pressure Pd is low and the front operation pressure Pf is high (for example, Pd ≦ Pd1, Pf ≧ Pf2), the variable throttle 161 switches to the position (B) regardless of the pump discharge pressure Pp. When the front working device is fully operated during the traveling fine operation, the pump discharge pressure Pp increases following the operation of the front working device, so the flow rate of the pressure oil supplied to the traveling motor 115 by the variable throttle 161 Limit.

  As described above, when the travel single operation state is changed to the composite operation state, the variable throttle 161 is switched to the position (B), so that the flow rate of the pressure oil supplied to the travel motor 115 is compared with the travel single operation state. Therefore, in the state where the wheel excavator 100 is traveling at a low speed, an increase in the flow rate of the pressure oil to the traveling motor 115 due to the operation of the front work device can be suppressed. That is, it is possible to reduce or prevent the phenomenon of the wheel excavator 100 popping out due to the front work operation being performed during the traveling operation.

According to 1st Embodiment described above, there can exist the following effects.
(1) The variable throttle 161 is controlled according to the travel operation pressure Pd, the front operation pressure Pf, and the discharge pressure Pp of the main pump 130. In the controller 120, the travel operation pedal 155 is operated and the boom operation lever 156 or the arm is operated from the travel single operation state in which the travel operation pedal 155 is operated and the boom operation lever 156 and the arm operation lever 157 are not operated. When the control lever 157 is operated in the combined operation state, a control current is output to the electromagnetic proportional valve 162 to control the variable diaphragm 161 so that the opening area of the variable diaphragm 161 becomes small. That is, in the present embodiment, the flow rate of the pressure oil supplied to the traveling motor 115 is controlled by the controller 120, the electromagnetic proportional valve 162, and the variable throttle 161 so as to suppress the phenomenon of the wheel shovel 100 popping out.

  In a state where the traveling operation pressure Pd is low (for example, Pd ≦ Pd1), the smaller one of the opening area Af calculated by the front operation pressure Pf and the opening area Ap calculated by the discharge pressure Pp of the main pump 130 is smaller. The variable aperture 161 is controlled by setting the target opening area At. The variable throttle 161 is controlled so that the opening area becomes smaller as the front operation pressure Pf is higher or the pump discharge pressure Pp is higher in a state where the travel operation pressure Pd is low (for example, Pd ≦ Pd1).

  Thereby, the traveling excavation phenomenon caused by the traveling wheel excavator 100 performing an operation other than traveling (for example, a boom raising operation or an arm raising operation) can be reduced or prevented. Thereby, a comfortable ride can be provided to an operator who operates the wheel excavator 100.

(2) The controller 120 determines that the flow restriction condition is satisfied when the traveling operation pressure Pd equal to or greater than the predetermined value Pt1 is detected and the front operation pressure Pf equal to or greater than the predetermined value Pt2 is detected. When it is determined that the flow rate restriction condition is satisfied, the controller 120 switches so that the control for restricting the flow rate by the variable throttle 161 according to the traveling operation pressure Pd, the front operation pressure Pf, and the pump discharge pressure Pp is enabled. The part 181 is switched to the position (A). On the other hand, if it is determined that the flow rate restriction condition is not satisfied, the controller 120 switches the switch unit 181 to the position (B) so that the control for restricting the flow rate by the variable throttle 161 becomes invalid.

  Thereby, in the traveling single operation state, the flow rate of the pressure oil supplied to the traveling motor 115 by the variable throttle 161 is not limited. For example, when the pump discharge pressure Pp rises during uphill travel, the opening area of the variable throttle 161 does not decrease according to the characteristic f3, and a decrease in travel driving force is prevented.

-Second embodiment-
A travel control apparatus according to the second embodiment will be described with reference to FIG. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and differences will be mainly described. FIG. 5 is a diagram similar to FIG. 3, and is a block diagram of a travel control apparatus according to the second embodiment of the present invention.

  In the first embodiment, the condition determination unit 180 determines whether or not the flow restriction condition is satisfied based on the determination results of the traveling operation determination unit 121 and the work operation determination unit 122. On the other hand, in the second embodiment, the condition determination unit 280 restricts the flow rate based on the determination result of the reduction ratio determination unit 283 in addition to the determination result of the traveling operation determination unit 121 and the work operation determination unit 122. It is determined whether the condition is satisfied.

  Controller 120 functionally includes a reduction ratio determination unit 283 that determines whether or not the reduction ratio is equal to or greater than a predetermined value in accordance with a control signal from shift switch 158. When the transmission switch 158 is set to the first speed, the reduction ratio determination unit 283 determines that the reduction ratio is greater than or equal to a predetermined value, and when the transmission switch 158 is set to the second speed, the reduction ratio determination unit 283 It is determined that the reduction ratio is less than a predetermined value.

  The condition determination unit 280 performs a work operation according to signals from the work operation determination unit 122 and the travel operation determination unit 121, indicates that a travel operation is performed, that is, a composite operation is performed, and deceleration is performed. It is determined based on a signal from the ratio determination unit 283 whether the reduction ratio is equal to or greater than a predetermined value. If the condition determination unit 280 determines that the composite operation is performed and the reduction ratio is equal to or greater than a predetermined value, the condition determination unit 280 determines that the flow rate restriction condition is satisfied, and outputs an ON signal to the switch unit 181. When the ON signal is input, the switch unit 181 is switched to the terminal (A) side. The condition determination unit 280 indicates that the work operation is not performed, the travel operation is not performed, or the signal from the work operation determination unit 122, the travel operation determination unit 121, and the reduction ratio determination unit 283, or If it is determined that the reduction ratio is less than the predetermined value, it is determined that the flow restriction condition is not satisfied, and an OFF signal is output to the switch unit 181. When an off signal is input, the switch unit 181 switches to the terminal (B) side.

  Thus, in the second embodiment, the controller 120 detects the traveling operation pressure Pd that is equal to or higher than the predetermined value Pt1, detects the front operating pressure Pf that is equal to or higher than the predetermined value Pt2, and is equal to or higher than the predetermined value. When the reduction ratio is detected, it is determined that the flow restriction condition is satisfied. When it is determined that the flow rate restriction condition is satisfied, the controller 120 switches so that the control for restricting the flow rate by the variable throttle 161 according to the traveling operation pressure Pd, the front operation pressure Pf, and the pump discharge pressure Pp is enabled. The part 181 is switched to the position (A). On the other hand, if it is determined that the flow rate restriction condition is not satisfied, the controller 120 switches the switch unit 181 to the position (B) so that the control for restricting the flow rate by the variable throttle 161 becomes invalid.

  Therefore, according to 2nd Embodiment, in addition to the effect similar to 1st Embodiment, there exist the following effects. The pop-out phenomenon occurs when the discharge pressure of the main pump 130 is lower than the actuator for the front work device on the high pressure side when a work operation such as raising the boom is performed while traveling at a low speed or low speed with a relatively low driving pressure. It is generated by acting on the traveling motor 115. In the second embodiment, in the state where the reduction ratio is high, that is, in the state where the driving pressure of the traveling motor is low, the flow rate of the pressure oil supplied to the traveling motor 115 is changed to a variable throttle 161 in order to reduce or prevent the popping out phenomenon. The flow rate restriction control is performed by restricting the flow rate. On the other hand, in a state where the reduction ratio is low, that is, in a state where the driving pressure of the traveling motor is high, the pop-out phenomenon is less likely to occur than in a state where the reduction ratio is high. Do not perform flow restriction control to throttle. Thereby, it is possible to prevent the driving force of the traveling motor 115 from being lowered when the traveling single operation state is changed to the combined operation state in a state where the reduction ratio is low.

-Third embodiment-
A travel control apparatus according to the third embodiment will be described with reference to FIG. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and differences will be mainly described. FIG. 6 is a diagram similar to FIG. 2 and is a diagram showing a schematic configuration of a travel control apparatus according to the third embodiment of the present invention.

  The travel control apparatus according to the third embodiment is configured such that the pressure of the main pipelines LA and LB of the travel motor 115 selected by the high pressure selection valve 394, that is, the pressure of the pressure oil supplied to the travel motor 115 (travel drive pressure Pm). ) Is detected. When the operation levers 156 and 157 for work are operated during traveling, the flow rate of the pressure oil supplied to the traveling motor 115 increases as the traveling drive pressure Pm is lower than the work load pressure. For this reason, in the third embodiment, the opening area of the variable diaphragm 161 is increased by taking into account the characteristic f6 that the opening area is reduced as the traveling drive pressure Pm is decreased and the opening area is increased as the traveling drive pressure Pm is increased. Set.

  FIG. 7 is a diagram similar to FIG. 3, and is a block diagram of a travel control apparatus according to the third embodiment of the present invention. FIG. 8 is a diagram showing characteristics used in the fourth calculation unit 384 shown in FIG. 7, and shows the relationship between the travel drive pressure Pm and the opening area Am.

  In the third embodiment, the controller 120 includes a fourth calculation unit 384 that calculates the opening area Am of the variable throttle 161 from the pressure Pm detected by the pressure sensor 374, a maximum value selection unit 326, and a minimum value selection unit. 327 functionally.

  The fourth calculation unit 384 calculates the opening area Am of the variable throttle 161 that monotonously increases as the detected value (traveling drive pressure) Pm of the pressure sensor 374 increases based on the predetermined characteristic f6 shown in FIG. To do. As shown in FIG. 8, according to the characteristic f6, when the detection value Pm is equal to or less than the predetermined value Pm1, the opening area Am is the minimum value Amin, and when the detection value Pm is in the range from Pm1 to Pm2, the opening increases as the detection value Pm increases. The area Am increases exponentially from the minimum value Amin to the maximum value Amax. According to the characteristic f6, when the detection value Pm is equal to or greater than the predetermined value Pm2, the opening area Am becomes the maximum value Amax.

  The maximum value selection unit 326 compares the opening area Ap calculated by the third calculation unit 125 with the opening area Am calculated by the fourth calculation unit 384, and determines which of the opening area Ap and the opening area Am The larger one is selected as the second opening area A2.

  The minimum value selection unit 327 compares the first opening area A1 selected by the maximum value selection unit 126 with the second opening area A2 selected by the maximum value selection unit 326, and compares the first opening area A1 and the first opening area A1. The smaller one of the two opening areas A2 is selected as the target opening area At.

  In the first embodiment, when both the traveling operation pressure Pd and the front operation pressure Pf are low (for example, Pd ≦ Pd1, Pf ≦ Pf1) and the pump discharge pressure Pp is high (for example, Pp ≧ Pp2). The variable aperture 161 is switched to the position (B). On the other hand, in the second embodiment, when both the travel operation pressure Pd and the front operation pressure Pf are low (for example, Pd ≦ Pd1, Pf ≦ Pf1), and the pump discharge pressure Pp is high (for example, , Pp ≧ Pp2), when the travel drive pressure Pm is high (for example, Pm ≧ Pm2), the variable throttle 161 is switched to the position (A).

In the third embodiment, for example,
(Α) When both the travel operation pressure Pd and the front operation pressure Pf are low and the pump discharge pressure Pp is high (for example, Pd ≦ Pd1, Pf ≦ Pf1, Pp ≧ Pp2), the travel drive pressure Pm is low. Sometimes (for example, Pm ≦ Pm1), the variable diaphragm 161 switches to the position (B). As a result, for example, when a heavy load operation is performed by finely operating the boom operation lever 156 during low-speed traveling on a flat road, the pop-out phenomenon is reduced or prevented. On the other hand, when the traveling drive pressure Pm is high (for example, Pm ≧ Pm2), the variable aperture 161 is switched to the position (A). Thereby, for example, when the heavy load operation is performed by finely operating the boom operation lever 156 while traveling at a low speed on an uphill road, it is possible to prevent the traveling driving force from being lowered.

  In addition, for example, when the heavy load operation is performed by finely operating the boom operation lever 156 while traveling on a flat road at a low speed, the opening area of the variable throttle 161 is reduced according to the sudden increase in the pump discharge pressure Pp. When the motor driving pressure Pm becomes higher following the pump discharge pressure Pp after the pop-out phenomenon is reduced or prevented, the opening area of the variable throttle 161 increases as the motor driving pressure Pm increases. The power can be prevented from decreasing.

  (Β) When the travel operation pressure Pd is low and the front operation pressure Pf is high (for example, Pd ≦ Pd1, Pf ≧ Pf2), the variable throttle 161 is positioned at the position (B) regardless of the pump discharge pressure Pp and the travel drive pressure Pm. Switch to. Thereby, for example, when the boom operation lever 156 is fully operated during the traveling fine operation, the pump discharge pressure Pp is increased following the operation of the front working device, and therefore supplied to the traveling motor 115 by the variable throttle 161. By restricting the flow rate of the pressurized oil, the pop-out phenomenon of the wheel excavator 100 can be reduced or prevented.

  According to such 3rd Embodiment, in addition to the effect similar to 1st Embodiment, there exist the following effects. The pop-out phenomenon occurs when the discharge pressure of the main pump 130 is lower than the actuator for the front work device on the high pressure side when a work operation such as raising the boom is performed while traveling at a low speed or low speed with a relatively low driving pressure. It is generated by acting on the traveling motor 115. In the third embodiment, for example, when the boom operation lever 156 is finely operated when a heavy load operation is performed during low speed traveling in a state where the traveling operation pressure Pd is low (for example, Pd ≦ Pd) (for example, , Pf ≦ Pf1), when the traveling drive pressure is low, the flow restriction control is executed to restrict the flow rate of the pressure oil supplied to the traveling motor 115 by the variable restrictor 161 in order to reduce or prevent the popping out phenomenon. On the other hand, when the traveling drive pressure is high during boom operation, the pop-out phenomenon is less likely to occur than when the traveling drive pressure is low. Therefore, the flow restriction control is performed to restrict the flow rate of the pressure oil supplied to the traveling motor 115 by the variable restrictor 161. Absent. Thereby, it is possible to prevent the driving force of the traveling motor 115 from being lowered in a state where the traveling driving pressure is high.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
[Modification]
(1) In the above-described embodiment, the work operation is performed based on the pilot secondary pressure generated by the pilot valve of the boom operation lever 156 or the pilot secondary pressure generated by the pilot valve of the arm operation lever 157. However, the present invention is not limited to this. Based on the pilot secondary pressure generated by the pilot valve of the bucket operation lever, it may be determined whether or not a work operation is being performed.

(2) In the above-described embodiment, the operation amount of the boom operation lever 156 or the arm operation lever 157 is detected by the pressure sensor 172, but the present invention is not limited to this. The operation amount of the boom operation lever 156, the arm operation lever 157 or the bucket operation lever may be detected by the pressure sensor 172.

(3) In the above-described embodiment, the pressure sensor 172 is used to detect the work operation and the pressure sensor 171 is used to detect the traveling operation. However, the present invention is not limited to this. For example, an angle sensor that detects an operation angle of the operation lever may be used.

(4) In the above-described embodiment, the travel operation determination unit 121, the work operation determination unit 122, and the condition determination unit 180 are provided, and when the flow rate restriction condition is satisfied, the flow rate restriction control is validated and the flow rate restriction condition is established. When not doing, the example in which the flow rate restriction control is disabled has been described, but the present invention is not limited to this. The traveling operation determination unit 121, the work operation determination unit 122, the condition determination unit 180, the maximum value setting unit 182 and the switch unit 181 may be omitted.

(5) The characteristics f1 to f6 used in the calculation units 123, 124, 125, 128, 129, and 384 of the above-described embodiment are not limited to those described above. The characteristics f1, f4, f5, and f6 are not limited to those increased exponentially, but may be increased linearly or stepwise. The characteristics f2 and f3 are not limited to those reduced exponentially, but may be reduced linearly or in stages.

(6) In the above-described embodiment, the example in which the present invention is applied to the wheel excavator 100 has been described. However, the present invention is not limited to this, and traveling of various wheeled work vehicles such as a wheel loader and a forklift is possible. It can be applied to a control device.

  Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

  DESCRIPTION OF SYMBOLS 100 Wheel excavator, 101 Running body, 102 Revolving body, 104 Driver's cab, 105 Wheel, 106 Boom, 107 Arm, 108 Bucket, 109 Counterweight, 110 Front work device, 115 Traveling motor, 116 Boom cylinder, 117 Arm cylinder, 118 Bucket cylinder, 120 controller, 121 traveling operation determination unit, 122 work operation determination unit, 123 first calculation unit, 124 second calculation unit, 125 third calculation unit, 126 maximum value selection unit, 127 minimum value selection unit, 128 control Pressure calculation unit, 129 Current calculation unit, 130 Main pump, 131 Pilot pump, 140 Valve unit, 145, 146, 147 Directional control valve, 150 Transmission, 151 Electromagnetic switching valve, 155 Traveling operation pedal, 156 Control lever, 157 arm control lever, 158 speed change switch, 161 variable throttle, 162 solenoid proportional valve, 171, 172, 173 pressure sensor, 180 condition determination unit, 181 switch unit, 182 maximum value setting unit, 190 engine, 191 center Bypass line, 195,196 High pressure selection valve, 199 tank, 280 Condition determination unit, 283 Reduction ratio determination unit, 326 Maximum value selection unit, 327 Minimum value selection unit, 374 Pressure sensor, 384 Fourth operation unit, 394 High pressure selection valve

Claims (5)

A hydraulic pump driven by an engine;
A travel motor driven by pressure oil discharged from the hydraulic pump;
An actuator for a working device that is driven by pressure oil from the hydraulic pump and drives a front working device;
A traveling direction control valve provided in a center bypass line of the hydraulic pump for controlling the flow of pressure oil supplied from the hydraulic pump to the traveling motor, and supplied from the hydraulic pump to the working device actuator A directional control valve for a working device that controls the flow of pressure oil;
A flow rate control valve that is provided on the upstream side of the travel direction control valve and that controls the flow rate of pressure oil supplied from the hydraulic pump to the travel motor;
A travel operation member for operating the travel motor;
A work operating member for operating the working device actuator;
Travel operation amount detection means for detecting an operation amount of the travel operation member;
Work operation amount detection means for detecting an operation amount of the work operation member;
A discharge pressure detecting means for detecting a discharge pressure of the hydraulic pump;
According to the travel operation amount detected by the travel operation amount detection means, the work operation amount detected by the work operation amount detection means, and the discharge pressure of the hydraulic pump detected by the discharge pressure detection means, Valve control means for controlling the flow rate control valve,
The valve control means is a composite in which the travel operation member is operated and the work operation member is operated from a travel single operation state in which the travel operation member is operated and the work operation member is not operated. A travel control device for a wheeled work vehicle, which controls a flow rate of pressure oil supplied to the travel motor so as to suppress a jump-out phenomenon of the wheeled work vehicle when an operation state is reached. In the traveling control device of the wheel type work vehicle according to claim 1,
Motor pressure detecting means for detecting the pressure of pressure oil supplied to the travel motor;
The travel control device for a wheel type work vehicle, wherein the valve control means controls the flow control valve in consideration of a pressure detected by the motor pressure detection means. In the traveling control device for a wheeled work vehicle according to claim 1 or 2,
The valve control means controls the flow control valve so that an opening area of the flow control valve is smaller than that in the traveling single operation state when the traveling single operation state is changed to the combined operation state. Thus, a traveling control device for a wheeled work vehicle is characterized by suppressing a jump-out phenomenon of the wheeled work vehicle. In the traveling control device of the wheel type work vehicle according to any one of claims 1 to 3,
A condition for determining that a flow restriction condition is satisfied when a travel operation amount greater than or equal to a predetermined value is detected by the travel operation amount detection means and a work operation amount greater than or equal to a predetermined value is detected by the work operation amount detection means. A determination means;
When the condition determining means determines that the flow restriction condition is satisfied, it is effective to control the flow control valve by the valve control means, and the flow restricting condition is satisfied by the condition determining means. When it is determined that there is not, a travel control device for a wheeled work vehicle, comprising valid / invalid means for invalidating control of the flow control valve by the valve control means. In the traveling control device of the wheel type work vehicle according to any one of claims 1 to 3,
A speed reduction mechanism capable of changing the speed reduction ratio, decelerating the rotation of the travel motor and transmitting it to the wheels;
A reduction ratio detecting means for detecting a reduction ratio of the reduction mechanism;
A travel operation amount greater than or equal to a predetermined value is detected by the travel operation amount detection means, a work operation amount greater than or equal to a predetermined value is detected by the work operation amount detection means, and a predetermined value or more is detected by the reduction ratio detection means. Condition determining means for determining that the flow restriction condition is satisfied when the reduction ratio is detected;
When the condition determining means determines that the flow restriction condition is satisfied, it is effective to control the flow control valve by the valve control means, and the flow restricting condition is satisfied by the condition determining means. When it is determined that there is not, a travel control device for a wheeled work vehicle, comprising valid / invalid means for invalidating control of the flow control valve by the valve control means.

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