JP2013227799A - Shift control device of front loader work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable work to be safely and efficiently carried out by automatically adjusting a traveling speed without adjusting the operation of a shift operating implement, when performing work for loading sediment in a bucket and moving the sediment by a front loader work vehicle of which speed is varied in a range from low speed to high speed by the shift operating implement.SOLUTION: In a shift control device of a front loader work vehicle, a bucket load sensor 66 is provided for detecting a load of sediment scooped by a bucket 75, and when the bucket load sensor 66 detects a load of a predetermined value or a larger value, the maximum speed achieved by operation of a shift operating implement 18 is controlled to be lowered. Moreover, when the bucket load sensor 66 detects a load of a predetermined value or a larger value, the acceleration ratio of the traveling speed accelerated by operation of the shift operating implement 18 is controlled to a low level.

Description

  The present invention relates to a shift control device for a front loader work vehicle.

  A front loader to be mounted on an agricultural tractor, etc. has a boom support frame standing on the left and right sides of the bonnet. The boom is supported on this frame so that it can be pivoted up and down, and a bucket is pivoted up and down at the tip of the boom. It is configured to support freely. Then, the boom is moved up and down by the expansion and contraction of the boom lifting hydraulic cylinder interposed between the support frame and the boom, and the bucket rotation hydraulic cylinder piston extending and retracting between the support frame and the boom. The bucket is configured to rotate up and down.

JP 2006-152707 A

  When carrying and transporting the earth and sand with the bucket of the front loader work vehicle, it is necessary to adjust the speed change operation tool for adjusting the traveling speed to low speed so that the earth and sand do not fall from the bucket.

  In the present invention, in a front loader working vehicle that shifts the traveling speed from a low speed to a high speed with a speed change operation tool, the travel speed is adjusted without adjusting the operation of the speed change operation tool when carrying out the work of loading and moving earth and sand in the bucket. It is an object to make it possible to adjust automatically to be able to work safely and efficiently.

  The problems of the present invention are solved by the following technical means.

  According to the first aspect of the present invention, a bucket load sensor 66 for detecting the load of earth and sand that is lifted by the bucket 75 is provided, and when the bucket load sensor 66 detects a load greater than a predetermined value, the maximum speed that can be changed by the transmission operating tool 18. It is set as the transmission control apparatus of the front loader work vehicle characterized by controlling so that it may fall.

  With this configuration, even if the shifting operation tool 18 is suddenly operated to the high speed side in order to move a lot of earth and sand with the bucket 75, the bucket load sensor 66 has a large amount of earth and sand in the bucket 75. Since the maximum traveling speed is limited when heavy is detected, it is safe without spilling soil from the bucket 75 due to high-speed traveling, and shifting operation that is not restricted when there is little soil in the bucket 75 and light. Work efficiently by moving at the maximum speed of the tool.

  The invention according to claim 2 is provided with a bucket load sensor 66 for detecting the load of earth and sand that is lifted by the bucket 75, and when the bucket load sensor 66 detects a load greater than or equal to a predetermined value, the shift operation tool 18 accelerates by a speed change operation. The speed control device for the front loader work vehicle is characterized in that the speed increase rate of the traveling speed is controlled to be low.

  With this configuration, even if there is a case where the shifting operation tool 18 is shifted to a high speed side in order to move a lot of earth and sand with the bucket 75, the bucket load sensor 66 has a large amount of earth and sand in the bucket 75 and is heavy. If this is detected, the speed increase rate of the traveling speed is limited to a low value, so that the aircraft does not shake due to sudden acceleration and spills from the bucket 75, and is safe when there is little earth and sand in the bucket 75. Work efficiently by moving at a speed increase rate.

  According to a third aspect of the present invention, a boom (77) projecting forward from the fuselage is lifted and lowered by a boom lifting cylinder (78), and a bucket (75) pivotally supported at the tip of the boom (77) is moved to a bucket rotating cylinder. The boom hydraulic sensor for detecting the hydraulic pressure of the boom elevating cylinder (78) is a bucket load sensor (66). The shift control device for a front loader work vehicle described in the above section.

  With this configuration, the load applied to the bucket 75 can be directly and accurately detected by the boom hydraulic pressure sensor 66 to control the maximum traveling speed or the speed increase rate of the traveling speed.

  The invention according to claim 4 controls the hydraulic pressure of the boom elevating cylinder 78 after the bucket 75 is rotated upward by the bucket rotating cylinder 79 as the bucket load. A shift control device for a work vehicle is provided.

  With this configuration, the traveling speed can be controlled by accurately detecting the weight of the earth and sand in the bucket 75 without using the weight when the bucket 75 digs up the earth and sand as the weight of the earth and sand that has been squeezed into the bucket 75.

  According to the first aspect of the present invention, even if the shifting operation tool 18 is suddenly operated to the high speed side in order to move a large amount of earth and sand with the bucket 75, the bucket load sensor 66 is provided in the bucket 75. The maximum traveling speed is limited when it is detected that the amount of sediment is large and heavy, so it is safe without spilling from the bucket 75 due to shaking of the aircraft at high speed, and when there is little sediment in the bucket 75 and light Can move efficiently at the maximum speed of the uncontrolled speed changer.

  According to the second aspect of the present invention, the bucket load sensor 66 does not change the earth and sand in the bucket 75 even when the gear shifting operation tool 18 is shifted to the high speed side in order to move a lot of earth and sand with the bucket 75. When it detects that the amount is heavy and heavy, the speed increase rate of the traveling speed is limited to a low level, so the aircraft does not sway due to sudden acceleration and is safe without spilling from the bucket 75, and there is little earth and sand in the bucket 75. In some cases, the work can be efficiently performed by moving at a speed increase rate that is not restricted.

  According to the third aspect of the present invention, the load applied to the bucket 75 can be directly and accurately detected by the boom hydraulic sensor 66 to control the maximum traveling speed or the speed increasing rate of the traveling speed.

  In the invention according to claim 4, the weight of the earth and sand in the bucket 75 is not detected as the load when the earth and sand is dug in the bucket 75, and the traveling speed is determined by accurately detecting the weight of the earth and sand in the bucket 75. Can be controlled.

It is a whole side view of a front loader work vehicle. It is the whole front loader work vehicle top view except a cabin. It is a power transmission block diagram. It is a control block diagram of automatic control. It is a graph showing the relationship between a drive current and HST output-shaft rotation speed. It is a top view of a maximum speed dial. It is a graph showing the relationship between the operation position of an accelerator pedal and a drive current value. It is an assembly perspective view of a steering handle. It is a perspective view of a transmission panel. It is a perspective view of a rear-wheel fender. It is a perspective view of a seat support frame. It is an assembly perspective view of a sheet. It is a starting circuit diagram of an engine. It is an engine starting circuit diagram of another Example. It is a side view of the neutral detection part of an accelerator pedal. It is an output graph which shows the relationship between driving speed and the throttle opening of an engine.

  As an example of the front loader working vehicle, an embodiment in which a front loader 69 is attached to the front portion of the body of the tractor 1 will be described below.

  In the present specification, the left and right directions in the forward direction of the work vehicle are referred to as left and right, respectively, the forward direction is referred to as front, and the reverse direction is referred to as rear.

  As shown in FIGS. 1 and 2, the tractor 1 includes a pair of left and right front wheels 2 and 2 and a pair of left and right rear wheels 3 and 3 at the front and rear portions of the aircraft, and includes an engine 5 mounted in a hood 39 at the front of the aircraft. Rotational power is appropriately decelerated by the HST 21 in the transmission case 8 and the auxiliary transmission 22 and transmitted to the front wheels 2, 2 and the rear wheels 3, 3.

  A steering handle 7 is provided at the handle post 6 in the cabin 4 at the center of the machine body, and a seat 9 is provided behind the steering handle 7. Below the steering handle 7 is provided a forward / reverse lever 10 for switching the advancing direction of the airframe to the front / rear direction. When the forward / reverse lever 10 is tilted forward, the aircraft moves forward, and when it is tilted rearward, the aircraft moves backward.

  An accelerator lever 11 for adjusting the engine speed is provided on the opposite side of the forward / reverse lever 10 with the handle post 6 in between, and an accelerator pedal for adjusting the traveling speed (main book) is provided at the right front corner portion of the step floor 13. The left and right brake pedals 19R and 19L for operating the brakes are provided. In addition, when the auto-cruise traveling is performed at a constant speed, the auto-cruise traveling is canceled when the brake pedals 19R and 19L are depressed.

  Further, on the side of the seat 9, a cross lever 41 (see FIG. 4) is provided for operating the boom 77 of the front loader 69 up and down and the bucket 75 up and down.

  The front loader 69 is attached to the front part of the tractor 1. The loader attachment bracket 74 is attached to the vehicle body frame 73 on both the left and right sides of the bonnet 39 of the tractor 1, and the boom support frame 76 is attached to the rear part of the loader attachment bracket 74. The boom 77 extending forward is attached to the upper end portion of the boom support frame 76 by a first horizontal shaft 82 so as to be rotatable up and down. Between the boom 77 and the boom support frame 76, a boom elevating cylinder 78 serving as an elevating actuator is interposed, and the boom 77 is rotated up and down by an expansion and contraction operation of a piston of the boom elevating cylinder 78. It has become.

  A bucket 75 is attached to the tip of the boom 77 so as to be rotatable up and down by a second horizontal shaft 83, and between the bucket 75 and the boom 77, a bucket rotation cylinder 79 serving as a bucket rotation actuator. Are attached via links 80 and 81, and the bucket 75 is rotated up and down by the expansion and contraction operation of the piston of the bucket rotation cylinder 79.

  Further, an emergency stop pedal 70 is provided on the right side on the seat 9 side on the step floor 13, and a differential lock lever 71 and a parking lever 72 are also provided on the left side on the seat 9 side. When the emergency stop pedal 70 is used, the engine 5 is stopped and the vehicle stops suddenly. Therefore, the emergency stop pedal 70 can be stopped more quickly than when the brake pedals 19R and 19L are used. However, if the HST 21 is returned to neutral, the stop distance can be shortened. A switch for switching the stopping method may be provided near the emergency stop pedal 70. When the parking lever 72 is pulled to apply the brake, the parking is stopped and the auto-cruise traveling is canceled.

  The emergency stop pedal 70 may be provided in combination with the brake pedals 19R and 19L.

  The accelerator pedal 18 controls the change of the rotation of the engine 5 together with the shift of the HST 21. However, the shift pedal of the HST 21 and the shift pedal of the engine 5 are separately provided in parallel to change the shift of the HST 21 and change the rotation of the engine 5. It may be possible to maintain the rotation of the engine 5 constant even if it is properly used, or when the shifting pedal is released and returned, or to be linked together so that the shifting of the HST 21 and the shifting of the engine 5 can be linked.

  In addition, you may provide the clutch pedal which cut | disconnects the clutch in the transmission case 8 along with brake pedal 19R, 19L.

  The accelerator pedal 18 and the brake pedals 19R and 19L are erected on the right side of the handle post 6, but a lateral pivot shaft is provided across the handle post 6, and the base is pivotally supported on the lateral pivot shaft. Brake pedals 19R, 19L and an accelerator pedal 18 may be arranged in parallel on the right side of the handle post 6, and the accelerator pedal 18 may be arranged on the right side of the handle post 6 and the brake pedals 19R, 19L may be distributed on the left side. .

  The accelerator pedal 18 may be divided into a forward accelerator pedal and a reverse accelerator pedal. At that time, a clutch pedal may be provided on the left or right side of the brake pedals 19R and 19L.

  A damper that adjusts the stepping load may be provided at the interlocking portion of the accelerator pedal 18 with the HST 21, or the position of the accelerator pedal 18 may be changed to the left and right.

  A meter panel 16 is provided on the front side of the steering handle 7 at the upper part of the handle post 6 to display the vehicle status such as traveling speed, and an engine rotation setting dial 14 is provided at the lower right part to set the maximum number of revolutions of the engine 5. I can do it. On the meter panel 16, the operation amount of the response setting dial 55 and the operation amount of the maximum speed setting dial 54 may be displayed, or the engine speed during auto-cruising may be displayed.

  Further, the transmission panel 87 on the left front side portion of the seat 9 is provided with an auxiliary transmission lever 15 that can select any one of a low speed, a medium speed, a high speed, and a neutral position, and a PTO transmission lever 12 is provided behind the auxiliary transmission lever 15.

  The right-side servo panel 91 of the seat 9 is provided with a maximum speed setting dial 54, a response setting dial 55, and an auto cruise set switch 56. The drive current value set by the maximum speed setting dial 54 is determined based on the control data stored in the adjustment mode to be described later, and as shown in FIG. Set evenly.

  100% with the maximum speed setting dial 54 means that the variable capacity motor 21b is at the maximum speed at a low speed or at a high speed. The maximum speed setting is ignored.

  When the auto cruise set switch 56 is turned on, the traveling speed is maintained and the vehicle travels at a constant speed, and is used during seeding work on a farm field or traveling traveling on a flat road.

  To cancel the auto-cruise running, the brake pedals 19R and 19L are depressed, the accelerator pedal 18 is depressed again, and the auto-cruise set switch 56 is turned on again. A sensitivity adjustment switch may be provided near the auto cruise set switch 56.

  Further, an auto cruise switching switch for turning on / off the auto cruise may be provided so that the auto cruise is not canceled even in the auto cruise cancel operation.

  The automatic cruise switching may be configured not by a switch but by an automatic cruise switching lever that is turned on and off by rotating back and forth near the seat 9. At that time, an emergency stop may be made when the auto-cruise switching lever is further rotated from the off side.

  In addition, a sensor for detecting that the operator is seated on the seat 9 is provided, and safety is ensured by stopping the engine 5 when detecting that the operator has stood up and separated from the seat 9 during auto-cruise. Also good.

  The maximum speed setting dial 54, the response setting dial 55, and the auto cruise set switch 56 may be arranged on a steering column 85 provided at the rear portion of the steering handle 7 as shown in FIG.

  Further, as shown in FIG. 9, it may be provided on the left side of the transmission panel 87, or may be provided on the front side of the fender 88 of the right rear wheel 3, as shown in FIG. Further, it may be provided on the front side surface of the seat support frame 89 of the seat 9 or may be provided on the armrest 90 of the seat 9 as shown in FIG.

  FIG. 3 is a power transmission block diagram, in which the rotation of the output shaft of the engine 5 is transmitted to the rear wheel drive shaft 27 of the differential case 23 via the damper 20 in the transmission case 8, the HST 21, and the auxiliary transmission unit 22. , 3 are driven. The HST 21 is composed of a variable displacement pump 21a and a variable displacement motor 21b. When the swash plate of the variable displacement pump 21a is rotated, the speed is changed from the forward rotation high speed to the reverse rotation high speed, and the swash plate of the variable displacement motor 21b is rotated. Then, the speed is changed to two stages of high speed and low speed, and the speed is changed by appropriately controlling the swash plate of the variable displacement pump 21a and the swash plate of the variable displacement motor 21b by the travel system ECU 50 described later. Further, the sub-transmission unit 22 shifts in three stages of high, medium, and low by gear shift.

  Although not shown, the driving force is branched in the transmission case 8 so that the front wheels 2 and 2 are also driven.

  The rotation of the output shaft of the HST 21 is detected by the HST output shaft sensor 25 as the rotation of the rotation sensor gear 24, and the output shaft rotation of the auxiliary transmission unit 22 is detected by the rear axle rotation sensor 26 as the rotation speed of the rear wheel drive shaft 27. Since the HST output shaft sensor 25 and the rear axle rotation sensor 26 calculate the time required to detect the predetermined number of teeth of the sensor gear, the number of rotations at a high speed can be obtained by setting the number of teeth to 1 at low speed and 3 teeth at high speed. It can detect accurately and stop quickly.

  FIG. 4 is a control block diagram of automatic control for controlling the operation of each part of the tractor. The engine ECU 29 for controlling the output of the engine E, the front loader ECU 40 for controlling the front loader 69, the front wheel 2 and the rear wheel 3 are controlled. And a traveling system ECU 50 that controls the traveling speed, and communicates control signals by CAN communication.

  Input of control data to the engine ECU 29 includes boost pressure from the boost pressure sensor 30, correction signal from the boost pressure correction control switch 36, exhaust temperature from the engine exhaust temperature sensor 31, and engine from the engine rotation sensor 32. The rotation speed of the output shaft, the oil pressure from the engine oil pressure sensor 33, the radiator water temperature from the engine water temperature sensor 34, the fuel pressure on the common rail from the rail pressure sensor 35, and the depression angle of the accelerator pedal 18 of the accelerator sensor 28 The control output from the engine ECU 29 is the rail pressure to the fuel high pressure pump 37 and the injection signal to the high pressure injector 38.

  The boost pressure correction control switch 36 turns on / off the control for gradually increasing the fuel injection amount when the accelerator lever 11 rotates when the boost pressure is low.

  Input of control data to the front loader ECU 40 includes an operation signal of the cross lever 41 for moving the bucket 75 up and down and turning up and down, and a hydraulic pressure of the boom hydraulic sensor 66 for detecting the hydraulic pressure of the boom lifting cylinder 78 that lifts and lowers the boom 77. The control output from the front loader ECU 40 is raised to the rising sol (solenoid) 45 and the lowering sol (solenoid) 46 of the boom raising / lowering cylinder 78 by the hydraulic pressure of the bucket hydraulic sensor 48 that detects the hydraulic pressure of the bucket rotation cylinder 79. A lowering signal and a vertical rotation signal to the bucket rotation sol (solenoid) 47 of the bucket rotation cylinder 79.

  Input of control data to the travel system ECU 50 includes the output shaft rotational speed of the HST 21 of the HST output shaft sensor 25, the rotational speed of the rear wheel drive shaft 27 of the rear axle rotational sensor 26, and the maximum speed set by the maximum speed setting dial 54. A response of the response setting dial 55, an ON / OFF signal of the auto cruise set switch 56, an operating position of the forward / reverse lever operating position sensor 64 of the forward / reverse lever 10, and an auxiliary shifting lever operating position of the auxiliary shifting lever 15 The operation position of the sensor 57, the depression signal of the accelerator pedal sensor 58 that detects the depression position of the accelerator pedal 18, the engine rotation setting signal of the accelerator sensor 59 provided in the accelerator lever 11, and the oil in the transmission case 8 of the oil temperature sensor 60 Temperature and brake pedal depression signal of brake pedal operation detection sensor 61 The travel acceleration of the acceleration detection sensor 52, the engine speed of the engine rotation sensor 32 of the engine 5, the on / off signal of the fully automatic shift switch 67, the on / off signal of the hydraulic motor shift switch 68, and the left brake sensor The control output from the travel system ECU 50, such as a 19LS left brake depression signal and a right brake depression signal of the right brake sensor 19RS, is sent to the swash plate angle output signal to the pump swash plate solenoid 62 and to the motor swash plate solenoid 63. A swash plate angle output signal, an alarm signal to the alarm buzzer 51, and the like.

  When the fully automatic shift switch 67 is turned on, both the variable displacement pump 21a and the variable displacement motor 21b are shifted, and when the hydraulic motor shift switch 68 is turned off, the variable displacement motor 21b is not shifted.

  The traveling speed, the shift position, the engine water temperature, and other data are displayed on the meter panel 16 and the operation panel 65 provided in front of the steering handle 7.

  FIG. 5 shows the relationship between the drive current value applied to the pump swash plate solenoid 62 and the motor swash plate solenoid 63 for controlling the hydraulic cylinder that rotates the trunnion shaft of the HST 21 and the HST output shaft rotational speed detected by the HST output shaft sensor 25. In the design, it is assumed that the design change line A indicated by the solid line fluctuates in the design, but the actual measurement data depends on the characteristics of the HST 21 and each body, and the actual measurement data is the shift width B. There is a variation in the maximum rotational speed width C. The drive current value and the measurement data of the HST output shaft rotational speed which are different for each aircraft are stored in the traveling system ECU 50 as control data.

  The adjustment mode is performed in a state where the assembly of the tractor 1 is finished and the sub-shift lever 15 is neutral and the driving after the HST 21 is turned off and no traveling load is applied at the final adjustment.

  First, in the measurement on the forward side, as the data at the time of acceleration, the drive current is changed from near zero where the HST 21 does not rotate to the maximum drive current value D sufficient to obtain the maximum rotational speed J, and the output shaft rotation of the HST 21 The number of rotations is measured, and the driving start current value F at the start of rotation and the maximum acceleration speed H near the maximum driving current value E of 90% of the maximum driving current D are stored in the traveling system ECU 50 as control data.

  Further, as data at the time of deceleration, the drive current is changed from the maximum drive current value D to near zero, and the maximum deceleration near rotation speed I and the drive stop current value G are stored in the traveling system ECU 50 as control data. The drive stop current value G can be accurately detected by actually running the tractor 1 and measuring it.

  Similarly to the above, on the reverse side, the deceleration side control data is stored in the traveling ECU 50.

  It should be noted that since there is a slight time lag for the drive current to be applied and the HST 21 to rotate, the rotation speed after a predetermined time has elapsed from the application of the drive current is used as control data.

  The rotation speed of the HST 21 depending on the depression depth of the accelerator pedal 18 uses the speed increase side drive start current value F, the speed increase maximum vicinity speed H, the speed reduction maximum vicinity speed I, and the drive stop current value G. The drive current value calculated from the calculated control change rate is applied to the pump swash plate solenoid 62 and the motor swash plate solenoid 63.

  As shown in FIG. 7, an HST neutral region in which output is prohibited is provided in the depression start range of the accelerator pedal 18, and the travel system ECU 50 outputs the drive start current value F at the acceleration start position at the end of the HST neutral region. To control. When the accelerator pedal 18 is depressed from the acceleration start position, the drive current value is rapidly increased so that the drive current linearly changes (proportional change) from zero rotation of the HST 21 to the maximum acceleration vicinity H. Further, a maximum maintenance margin angle is provided at the maximum depression position of the accelerator pedal 18 so that the maximum rotation speed J is output at the maximum drive current value.

  The maximum speed J is determined by the engine speed regulation. However, when the oil temperature sensor 60 detects a predetermined temperature or higher, the maximum drive current value D is set to the maximum speed setting dial 54 and the current value range and near the maximum. By further reducing the regulated drive current value to the lower drive current value E, further increase in the oil temperature is suppressed. The return of the drive current is lower than a predetermined temperature to prevent the occurrence of hunting.

  The regulated drive current value is determined by the drive current value calculated from the control change rate.

  When the depression of the accelerator pedal 18 is stopped and the driving of the HST 21 is stopped, the driving current for driving forward or backward driving is stopped and a driving current slightly larger than the driving start current value F in the reverse direction after a predetermined time has elapsed. Is applied for a short time (several tens of milliseconds), and the trunnion shaft is returned to the neutral position after returning to the normal position.

  When the accelerator pedal 18 is depressed to a predetermined high speed position or a predetermined high speed position or higher, a change rate of the depression speed is calculated, and according to the change rate, up to a constant change rate that does not overload the engine load, up to the pedal position corresponding speed. Change the speed increase rate. In addition, when the accelerator pedal 18 is stepped on beyond a predetermined high speed position, the speed acceleration rate is decreased when the predetermined speed acceleration rate elapses for a predetermined time, and the speed acceleration rate is canceled when the target speed is reached.

  From the traveling system ECU 50, the set traveling speed is obtained at the depression position of the accelerator pedal 18 using the control data of the maximum vicinity driving current value E, the driving start current value F, and the driving stop current value G detected above. A drive current is output to the pump swash plate solenoid 62 and the motor swash plate solenoid 63 to control the rotation of the trunnion shaft of the HST 21.

  When the accelerator pedal 18 is depressed most, a predetermined large drive current value is output to the pump swash plate solenoid 62 and the motor swash plate solenoid 63 instead of the drive current value based on the control data. Make sure they are not different.

  Further, even if the drive current value (rate) is increased, if the travel speed increase amount (rate) is lower than a predetermined value, the travel load is large, so that the increase in the drive current value is interrupted to prevent an engine stall. Further, when the engine speed reduction is larger than a predetermined rate, the drive current is reduced to prevent engine stall, and when the engine speed is close to the idling speed, the drive current is turned off and the HST 21 is made neutral. After that, when the engine speed returns to the set speed, the engine speed is slowly returned to a predetermined drive current at a predetermined change rate.

  In addition to the control using the measurement data of the drive current value and the HST output shaft rotation speed, the acceleration / deceleration acceleration is set by the response setting dial 55 so that the acceleration of the machine body detected by the acceleration detection sensor 52 becomes the set acceleration. It is also possible to control it. The control using the acceleration is not performed because it takes too much time to detect the acceleration in the low speed state, and the control is performed with the immediately preceding acceleration / deceleration rate.

  In addition, since control using this acceleration is difficult to detect a change in acceleration at a low speed, acceleration / deceleration is controlled by a drive current change rate of a separately set change rate line.

  The response setting dial 55 controls acceleration / deceleration at a predetermined drive current change rate according to the dial position without performing acceleration control. At the start of deceleration, the speed change after a certain time has elapsed since the current change. Is corrected by the acceleration detected by the acceleration detection sensor 52. The correction at the time of switching in the reverse direction immediately after the forward / reverse switching (forward → reverse or reverse → forward) is performed on the predetermined drive current change rate with the same amount of increase / decrease correction as the correction increase / decrease amount on the deceleration side.

  Further, the rotational speed of the engine 5 is regulated so that the rotational speed detected by the engine rotational sensor 32 does not exceed a predetermined rotational speed, but is slightly higher than that using the restricted rotational speed of the maximum speed setting dial 54. Set to the number of revolutions. Note that the maximum speed setting dial 54 may limit the travel shift range by limiting the rotation range of the trunnion shaft of the variable displacement pump 21a.

  The traveling speed is set by the accelerator pedal 18 and the auxiliary transmission lever 15, and the shift control is performed as follows.

  First, when the earth and sand moving work is performed at a low speed, the auxiliary transmission lever 15 is set to “low”, and traveling is started while gradually depressing the accelerator pedal 18. Then, the shift position of the auxiliary transmission lever 15 is read by the auxiliary transmission lever operating position sensor 57, the depression depth of the accelerator pedal 18 is read by the accelerator pedal sensor 58, and is input to the travel system ECU 50. A swash plate angle output signal is output to the plate solenoid 63, and the variable displacement pump 21a and the variable displacement motor 21b are shifted from the lowest speed to the traveling speed set by the accelerator pedal 18 and the auxiliary transmission lever 15.

  When the sub-shift lever 15 is set to “low” or “medium” to start traveling, the variable displacement motor 21b may shift from a medium speed other than the lowest speed while shifting the variable displacement pump 21a from the lowest speed. However, when the sub-shift lever 15 is set to “high” to start traveling, the variable displacement motor 21b is shifted from the lowest speed to prevent sudden start and start with a high driving torque.

  Further, the engine load factor is input from the engine ECU 29 to the traveling system ECU 50, and when the engine load factor is lower than the predetermined load factor, the auxiliary transmission lever 15 can be switched to the high gear shift range, so that the engine rotation at the time of speed increase is achieved. Decline can be prevented.

  Further, when the auxiliary transmission lever 15 is switched to the low speed change range, the engine 5 may be rotated at a low speed to prevent the engine from increasing due to a light load change and to achieve a smooth speed change.

  The traveling speed set by the accelerator pedal sensor 58 and the auxiliary transmission lever 15 is fed back to the pump swash plate solenoid 62 and the motor swash plate solenoid 63 by feeding back the rotational speed of the rear wheel drive shaft 27 detected by the rear axle rotation sensor 26. Adjust the swash plate angle output signal.

  The engine rotation setting dial 14 is used to set the rotation speed of the engine 5 to an arbitrary rotation speed lower than the maximum rotation speed, and is used when working at a low speed.

  The engine speed to be used is set at the engine speed indicated by the accelerator lever 11, but if an engine speed higher than the used engine speed is indicated by the accelerator pedal 18, the higher engine speed is given priority.

  When the sub-shift lever 15 is shifted from “medium” to “high” or from “low” to “medium”, the engine speed is low when the rotation speed detected by the rear axle rotation sensor 26 is low, and the engine rotation is not performed. Is not changed, but the rotational speed detected by the rear axle rotation sensor 26 is high and the rotational speed of the engine 5 is adjusted in the running state so as to eliminate a shift shock such as sudden acceleration. At that time, after the engine speed is reduced at once, the vehicle speed difference before and after the change is returned to the indicated rotational speed within a specified range within a specified acceleration.

  When the engine load factor at the time of returning to the commanded rotational speed is equal to or greater than a predetermined value, priority is given to setting a restriction on the subsequent engine rotational speed lowering instruction rather than the regulation within the vehicle speed difference regulation range.

  When the sub-shift lever 15 is shifted from “high” to “middle” or “middle” to “low”, the engine speed is increased at a stroke and then returned to the indicated rotational speed. At this time, if the pre-change engine speed instruction is in the vicinity of the maximum engine speed, the gear change speed is adjusted with a variable iris or the like so as to be slower than normal. Further, when the engine load factor before the change is near the maximum output, the engine speed is increased or decreased so as to be within the vehicle speed acceleration regulation.

  In addition, the vehicle speed acceleration after the shift is monitored, and the engine speed is increased or decreased so that the acceleration falls within the specified range. At that time, when it can be estimated that the engine load factor increases when the engine load factor is large, acceleration priority is stopped and load stabilization is prioritized.

  When the auto cruise set switch 56 is turned on when running at a constant speed, the running speed is maintained. However, when the auto cruise set switch 56 is turned on, output to the motor swash plate solenoid 63 is not performed. Thus, the variable displacement motor 21b is not shifted. This eliminates the speed fluctuation associated with the speed change of the variable capacity motor 21b, thereby achieving stable running.

  When the auto-cruise set switch 56 is turned off, the brake pedals 19R and 19L are depressed, or the parking lever 72 is pulled to apply the brake, the auto-cruise traveling is canceled. With this auto-cruise canceling operation, the variable displacement motor 21b The gear shift control is automatically revived to enable traveling corresponding to sudden fluctuations in traveling load.

  If the variable displacement motor 21b is controlled to shift by turning on the hydraulic motor shift switch 68 without automatically restoring the shift control of the variable displacement motor 21b, the driver of the work vehicle is driven. It can be recognized that there is a possibility that the running speed may become unstable due to torque fluctuation.

  Further, when the driving load exceeds a certain value, the alarm buzzer 51 is sounded or the warning light blinks to prompt the operator to turn on the hydraulic motor speed change switch 68. The fuel consumption increase time can be shortened.

  When the vehicle is traveling with the fully automatic transmission switch 67 turned on, if the engine speed suddenly decreases by a certain number of rotations due to an increase in traveling load, the variable displacement motor 21b is reduced after the traveling speed is reduced to the maximum low speed. Is switched from a high speed to a low speed to obtain a traveling speed supported by the accelerator pedal 18. In this case, when the rotary work machine 17 is at a low speed, the traveling speed is reduced.

  Or, when the vehicle is traveling with the fully automatic transmission switch 67 turned on, if the engine speed is suddenly decreased by a certain rotational speed due to an increase in traveling load, the engine speed is not restored even if the traveling speed is decreased by 25%. In this case, the variable displacement motor 21b is switched from high speed to low speed so that the traveling speed supported by the accelerator pedal 18 is achieved.

  The variable displacement motor 21b is switched from the low speed to the high speed while the acceleration pedal 18 is not instructed to increase or decrease the speed, the speed is increased to the maximum speed of the low speed or is immediately switched to the high speed and the speed increase is continued. .

  When the left brake sensor 19LS and the right brake sensor 19RS sense that the left and right brake pedals 19R and 19L are simultaneously depressed, they are output to the forward solenoid and the reverse solenoid of the pump swash plate solenoid 62, and according to the set value of the response setting dial 55 The vehicle is decelerated at the response speed, the output rotation of the variable capacity pump 21a is set to 0, and the motor is gradually decelerated and stopped. The response speed is the response speed changed to the insensitive side if the response setting dial 55 is equal to or higher than the intermediate value, and is set to the response speed set if the response setting dial 55 is equal to or lower than the intermediate value.

  At that time, if the simultaneous depression of the left and right brake pedals 19R, L is instantaneous for about 0.5 seconds, the above-described travel stop control is not performed.

  Further, the response speed of the pump swash plate solenoid 62 may be the above-described response speed for a predetermined time, and then the stop time may be shortened by increasing the response speed and suddenly stopping.

  The earth and sand moving work by the front loader 69 is performed by lowering the bucket 75 with the boom elevating cylinder 78 and moving the bucket 75 horizontally with the bucket rotating cylinder 79 to scoop up the earth and move forward. The bucket 75 is rotated downward to lower the earth and sand.

  In this series of operations, the hydraulic load detected by the bucket load sensor 66 becomes the load of the earth and sand that has entered the bucket 75 with the hydraulic pressure when the boom elevating cylinder 78 is raised. Even if the accelerator pedal 18 is depressed by lowering the speed increase rate, the travel speed does not become too fast or sudden acceleration disappears, so that the soil in the bucket 75 does not fall down.

  The hydraulic pressure detected by the boom hydraulic pressure sensor 66 also detects the load for digging up the sand and sand, so that the hydraulic pressure when raising the boom 77 is the weight of the earth and sand that the bucket 75 cites, or the bucket hydraulic pressure when the bucket 75 is rotated upward. The oil pressure of the sensor 48 and the oil pressure of the boom oil pressure sensor 66 after the bucket 75 is rotated upward and the oil pressure of the bucket oil pressure sensor 48 are set to the weight of the earth and sand, so that the weight of the earth and sand that the bucket 75 has crushed more accurately. Can be detected.

  The maximum travel speed and the speed increase rate are limited by controlling the pump swash plate solenoid 62 and the motor swash plate solenoid 63. However, the depression angle of the accelerator pedal 18 is mechanically limited. Also good.

  FIG. 13 is a drive circuit diagram of the engine 5, a sub-shift sensor 93 that detects the shift position of the sub-shift lever 15, an HST neutrality detection sensor 94 that detects the neutrality of the HST 21, and a brake operation detection sensor 95 for the brake pedals 19R and 19L. When the brake pedals 19R and L are depressed by the first relay 96 and the second relay 97 and the engine start key 92 is turned when the HST 21 is neutral, the start switch 98 is energized so that the engine 5 can be started. I have to. With this drive circuit, even if the HST 21 is neutral on the slope, the engine 5 will not start unless the brake pedals 19R, L are depressed, so that the aircraft is safe without slipping.

  FIG. 14 shows another embodiment of the drive circuit of the engine 5, which is turned on when the brake pedals 19R and L are depressed in parallel with the subshift relay 101 which is turned on when the subshift sensor 93 detects neutral of the subtransmission lever 15. The brake switch 100 and the HST switch 99 which are turned on when the HST 21 is neutral are provided. When the HST 21 is neutral and the brake pedals 19R and L are depressed even when the auxiliary transmission lever 15 is not neutral, the engine start key 92 is turned to start the switch. The engine 5 is energized so that the engine 5 can be started. With this drive circuit, even if the HST 21 is other than neutral on a slope, the engine 5 is started if the HST 21 is neutral by stepping on the brake pedals 19R and L.

  FIG. 15 shows a mounting configuration of the HST neutrality detection sensor 94 that detects that the HST 21 is neutral.

  FIG. 16 is an output graph showing the relationship between the traveling speed V due to the shift and the throttle opening S of the engine 5, and the current output position is displayed with a cursor K. This output graph is displayed on the meter panel 16 or displayed on a monitor provided in front of the armrest 90, and the cursor K is moved with a control lever or cross key provided near the seat 9, or the cursor on the direct display screen. It is also possible to adjust the optimum traveling speed and engine output by touching K.

18 Shifting operation tool (accelerator pedal)
66 Bucket load sensor (boom hydraulic pressure sensor)
75 Bucket 77 Boom 78 Boom elevating cylinder 79 Bucket rotating cylinder

Claims (4)

  A bucket load sensor (66) for detecting the load of earth and sand to be scooped up by the bucket (75) is provided, and when the bucket load sensor (66) detects a load exceeding a predetermined value, the maximum speed at which the speed can be changed by the speed change operation tool (18). A speed change control device for a front loader work vehicle, characterized in that it is controlled so as to decrease.   A bucket load sensor (66) for detecting the load of earth and sand to be scooped up by the bucket (75) is provided, and when the bucket load sensor (66) detects a load exceeding a predetermined value, it is accelerated by the operation of the transmission operation tool (18). A speed change control device for a front loader working vehicle, characterized in that the speed increase rate of the traveling speed is controlled to be low.   A boom (77) projecting forward from the machine body is raised and lowered by a boom lifting cylinder (78), and a bucket (75) pivotally supported at the tip of the boom (77) is vertically rotated by a bucket rotating cylinder (79). 3. The front loader working vehicle according to claim 1, wherein the boom hydraulic pressure sensor for detecting the hydraulic pressure of the boom lifting cylinder (78) is a bucket load sensor (66). Shift control device.   4. The front loader working vehicle according to claim 3, wherein the hydraulic pressure of the boom elevating cylinder (78) after the bucket (75) is rotated upward by the bucket rotating cylinder (79) is controlled as a bucket load. 5. Shift control device.

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