JP2008273311A - Work vehicle - Google Patents

Abstract

[PROBLEMS] To prevent sudden acceleration / deceleration during work travel of a work vehicle using a hydraulic continuously variable transmission.
A working vehicle that travels and transmits via a hydraulic continuously variable transmission (1) is provided with a stepping type HST pedal (32) that controls a trunnion shaft (3) of the hydraulic continuously variable transmission (1), and the HST pedal (32) is operated. Thus, the engine speed of the work vehicle is changed and the trunnion shaft 3 of the hydraulic continuously variable transmission 1 is controlled, and switching means for switching to work travel is provided, and the work travel is performed by the switching means. In the construction of the working vehicle, the control means 100 is provided that moves the rotational speed of the trunnion shaft 3 of the hydraulic continuously variable transmission 1 at a low rotational speed while traveling on the road.
[Selection] Figure 1

Description

  The present invention relates to a work vehicle such as a tractor that travels and transmits via an HST (hydraulic continuously variable transmission).

A technique (for example, refer to Patent Document 1) is known in which the amount of depression of an HST pedal is detected by a position sensor, and an HST trunnion shaft is operated to change speed.
Japanese Patent Laying-Open No. 2005-343187 (page 4, FIG. 1).

  In a mode in which the tractor travel control is performed by the trunnion control via the position sensor with the HST pedal, the throttle opens in proportion to the depression amount of the pedal, and when the PTO clutch is engaged, the operation is performed from the substantially full throttle state to the rated value. Become. At this time, the pedal operation force becomes lighter and the foot placed on the pedal becomes lighter on rough terrain, etc. It may slow down and it is difficult to run smoothly.

  The invention according to claim 1 is a stepping-type HST pedal that controls the trunnion shaft (3) of the hydraulic continuously variable transmission (1) in a work vehicle that travels and transmits via the hydraulic continuously variable transmission (1). 32) and operating the HST pedal (32) changes the engine speed of the work vehicle and also controls the trunnion shaft (3) of the hydraulic continuously variable transmission (1). Switching means for switching to traveling is provided, and in the state where work traveling is performed by the switching means, the rotational speed of the trunnion shaft (3) of the hydraulic continuously variable transmission (1) is rotated at a low speed with respect to traveling on the road. It is set as the structure of the working vehicle characterized by providing the control means (100) moved by speed.

  In a state in which the control means (100) provided on the work vehicle recognizes that the work vehicle is traveling, the traveling speed of the trunnion shaft (3) of the hydraulic continuously variable transmission (1) is set to a value other than the work traveling time. Move at a slow rotation speed.

  According to a second aspect of the present invention, in the vicinity of the steering handle (11) for steering the work vehicle, the engine speed of the work vehicle and the trunnion shaft (3) of the hydraulic continuously variable transmission (1) are controlled. The construction of the work vehicle according to claim 1, further comprising an accelerator lever (31) for performing the operation.

  An accelerator lever (31) provided in the vicinity of the steering handle (11) also changes the engine speed and controls the trunnion shaft (3).

  According to the first aspect of the present invention, the rotation speed of the trunnion shaft (3) is slowed during traveling other than work traveling when the switching means for switching to the working state is selecting working traveling. Therefore, rapid traveling acceleration, traveling deceleration, etc. can be eliminated, and impacts can be absorbed and traveling safety can be maintained. And smooth operation can be performed and the fuel consumption rate of an engine can be reduced.

  According to the second aspect of the present invention, the accelerator lever (31) provided in the vicinity of the steering handle (11) can also change the engine speed and control the trunnion shaft (3), so that the operability is improved. become.

  A multipurpose work vehicle (tractor) will be described with reference to FIGS. The vehicle body 6 of the multi-purpose tractor has a pair of left and right front wheels 7 and a rear wheel 8, and is provided with a cabin 12 covering the driver's seat 9, the steering handle 11 on the steering post 10, and the like on the rear side. 13 is arranged. The engine 14 is disposed in an engine room 15 formed below the chassis 13. A radiator 16, a radiator fan 17, and the like are disposed on the rear side of the engine 14. The HST input shaft 19 of the front side HST 1 (hydraulic continuously variable transmission) is linked from the engine 14 via the main clutch 18, and the auxiliary transmission input shaft 22 of the transmission case 21 on the front side is linked from this HST output shaft 20. The front wheel 7 is interlocked from the auxiliary transmission output shaft 23 via a front wheel differential gear 24 and the rear wheel 8 is interlocked via a rear wheel differential gear 25 or the like. In addition, a PTO shaft 28 that links a work machine such as a front mower is provided from a PTO output shaft 26 that is directly linked to the HST input shaft 19 at a constant speed via a transmission gear 27 and the like.

  The steering post 10 and the step floor 29 are provided with a reverser lever 30 for switching forward and backward driving of the HST 1, an accelerator lever 31 for adjusting the rotation of the engine 14, an HST pedal 32 for adjusting the angle of the trunnion shaft 3, a brake A pedal 33 and the like are arranged. The operation of the trunnion shaft 3 of the HST 1 detects the rotation of the engine 14 by the engine sensor 37, detects the depression amount of the HST pedal 32 by the pedal position sensor 4, and drives the trunnion motor 5 according to this detection amount. Then, the trunnion shaft 3 is driven while being detected by the trunnion position sensor 36 to continuously shift the HST1.

  The HST 1 is disposed in a part of the hydraulic circuit 40 having the hydraulic pump P 1, and the hydraulic circuit 40 steers the clutch cylinder 41 for operating the PTO clutch 2, the clutch control valve 42, and the front wheel 7. A front wheel steering cylinder 43 and a steering control valve 44 including an orbit roll, a rear wheel steering cylinder 45 for steering the rear wheel 8, a steering control valve 46, and the like are disposed. The hydraulic circuit of the HST 1 is configured in a closed circuit configuration in which charge oil is supplied from the hydraulic circuit 40 and maintained at a constant pressure. In this HST hydraulic circuit 1, an HST pump 47 and an HST motor 48 are arranged, the trunnion shaft 3 is driven by the trunnion motor 5, the swash plate angle of the HST 1 is changed, and the HST pump 47 is driven by the HST input shaft 19. The HST motor 48 is hydraulically driven by driving, and the HST output shaft 20 is controlled to be driven and rotated from the stop position to the forward rotation side or the high rotation position on the reverse rotation side, so that the HST output shaft 20 is rotated forward or backward. It is a continuously variable transmission. T is a tank port.

  Here, in a working machine that travels via HST1, the switching means for switching to work travel selects work travel, and this state is recognized by the control means 100 (controller) to transmit work travel, so that the trunnion of HST1 The trunnion control device is configured to perform relaxation control of three rotation speeds.

  As a specific configuration of the switching means for switching to the work travel, determination is made by turning on the PTO switch 2. As another determination method, the position of the auxiliary transmission lever or the like may be recognized.

  When the PTO switch 2 is turned on or off, output control is performed so as to slow down the operation speed of the trunnion motor 5 by the position sensors 4, 36, etc., so that the speed increasing operation or the speed reducing operation is performed gently.

  When working, the accelerator lever 31 can be operated to increase the rotation of the engine 14 beyond the rated rotation, but when the engine 14 is raised to the rated rotation by depressing the HST pedal 32, the PTO clutch 2 The main clutch 18 is engaged and the trunnion 3 shafts are operated to drive. By providing a PTO clutch sensor 39 for detecting the engagement of the PTO clutch 2 and detecting the engagement or disengagement of the PTO clutch 2 by the PTO clutch sensor 39, the initial operating speed of the trunnion triaxial by the HST pedal 32 is detected. Is controlled to decelerate (FIG. 1). In other words, the shift operation is performed at a slow speed over a long period of time so that the operation speed of the trunnion triaxial is made slower than the speed change operation speed by depressing the HST pedal 32. Further, the controlled shifting operation speed is not limited as long as it is controlled when the operating speed is higher than a predetermined speed, and is not limited to the speed increasing side for increasing the speed shifting but also when operated on the speed reducing side. It can be controlled similarly.

  The relationship between the detected value of the HST (forward / reverse) position sensor 4 by the depression of the HST pedal 32 and the control speed of the trunnion motor 5 is shown in the graph of FIG. When operating to the A side or the deceleration B side, the travel control line L is drawn as a slow line D in a state where the control speed is decelerated, while being the proportional line C of the HST pedal 32. Accordingly, when the HST pedal 32 is stepped on from the current position G to the speed increasing or deceleration side in the working state, the trunnion shaft 3 is not rotated according to the stepping amount of the HST pedal 32, but is predetermined. The trunnion shaft 3 is operated with a time delay. Therefore, when the PTO clutch 2 is engaged, the traveling control line L is switched from the proportional line C to the slow speed line D and output is controlled by detection of the PTO clutch sensor 39. Further, the control of the trunnion shaft 32 is configured to be controlled on both the speed increasing A side and the speed reducing B side, but may be configured to work only on the speed increasing A side.

  Next, mainly based on FIGS. 6 to 8, a step portion is formed between the upper portion of the hood 51 covering the engine room 15 and the chassis 13, and a net hood 52 is provided around the step portion. It is a thing. This hood 51 is formed with ventilation holes over the entire periphery to maintain good ventilation in the engine room 15 and a net hood 52 is formed between the engine room 15 and the chassis 13 above the engine room 15. Therefore, the air permeability in the engine room 15 can be improved, dust accumulation and suction can be reduced, and the cooling efficiency of the engine 14 can be increased. Further, as shown in FIG. 8, the net hood 52 has a non-hole hood 54 in which a vent hole 53 is formed on the front side of the radiator 16 in the engine room 15 and no vent hole is formed on the rear side. As a result, the engine exhaust muffler 55 can prevent the intake of hot exhaust gas exhausted rearward from the position of the radiator 16 and increase the engine cooling efficiency. Further, the muffler 55 is connected to the exhaust pipe 56 of the engine 14 and installed behind the radiator 16 to reduce heat generation and heating on the front side of the radiator 16 and improve the cooling efficiency of the radiator 16. Can do.

  Next, mainly based on FIG. 9, when the steering mode of the tractor is 4WS, the steering angle sensors 63 and 64 of the respective wheels are provided in the steering cylinders 61 and 62 of the front wheels 7 and the rear wheels 8, and the detection signals thereof Is input to the controller. When this signal causes a difference of 5% or more in the turning angle between the front wheel 7 and the rear wheel 8, the pilot lamp 66 provided on the control panel 65 for displaying the turning angle abnormality is blinked. When continuously running or working in the 4WS state, cylinder oil leaks depending on the load of each axis and the working mode, and there is a difference in front and rear wheel turning angles (cylinder movement amount). When this difference becomes large, not only a sense of incongruity during traveling but also steering may become impossible. In such a case, the pilot lamp 66 of the control panel 65 is blinked to notify the operator of an abnormal state. Further, when the cut angle difference is 5% or less, the pilot lamp 66 does not blink.

  In the 4WS mode, when the turning angles of the front and rear wheels 7 and 8 are different by 5% or more and the pilot lamp 66 is flashing, the traveling shift is set to the neutral position, the front wheel 7 is set in the straight traveling state, and the RWS When the mode switch 68 is pressed for 3 seconds, oil automatically flows into the rear wheel steering cylinder 62 so that the rear wheel 8 goes straight and controls the difference in the turning angle. Correction can be automatically performed by button operation, and safe and efficient work can be performed.

  Further, in such a mode that the steering mode of the tractor can be switched among 4WS, FWS, and RWS, only when the engine 14 is started, when the front and rear steering cylinders 61 and 62 are not in the straight traveling state, the steering mode An arbitrary steering mode can be selected by pressing the selection switch 67 for a predetermined time or longer. At this time, when any of the steering cylinders 61 and 62 is moved straight by the operation in the selected mode, the mode is automatically canceled and the steering target steering mode is set.

  The control panel 65 is provided with a mode forced changeover switch 69. When this switch is pressed for 3 seconds or more, the mode change lamp provided on the panel 65 blinks. In this blinking state, an arbitrary steering mode can be selected. At this time, the turning angle of the steering is set to a straight traveling (neutral) state. An arbitrary steering mode can be selected simply by pressing the forced changeover switch 69, and workability can be improved.

  Next, mainly based on FIG. 10, when correcting when a large error occurs in the turning angle between the front wheel 7 and the rear wheel 8 as described above, the front wheel 7 and the rear wheel 8 are corrected separately. It is configured. When the steering mode is set to the 4WS mode, if this is corrected while the 4WS mode is maintained, an error in the turning angle becomes large, and it becomes difficult to perform the correction, which is dangerous. Therefore, as shown in the flowchart in the figure, when the rear wheel 8 is not in the straight traveling state, the steering is stopped and the FWS mode is selected. At this time, when the front wheel 7 is in the straight traveling state, the mode is switched to the RWS mode. As a result, when the rear wheel 8 goes straight, the 4WS mode is restored.

The block diagram and control graph of work vehicle HST control. The side view of a work vehicle and the perspective view of the steering post part. The plan view. The top view of the transmission mechanism. The hydraulic circuit diagram. The side view and top view of a work vehicle which show another example. The enlarged side view of the one part. The perspective view of the net food part which shows a part another example. The top view which shows a steering mode state, and the top view of a control panel part. The flowchart which correct | amends the turning angle difference of a front-and-back wheel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic continuously variable transmission 2 PTO clutch 3 Trunnion shaft 11 Steering handle 31 Accelerator lever 32 HST pedal 100 Control means (controller)

Claims (2)

  A work vehicle that travels and transmits via the hydraulic continuously variable transmission (1) is provided with a stepping type HST pedal (32) that controls the trunnion shaft (3) of the hydraulic continuously variable transmission (1). 32), the engine rotational speed of the work vehicle is changed and the trunnion shaft (3) of the hydraulic continuously variable transmission (1) is controlled, and switching means for switching to work travel is provided. In a state where the traveling is performed by the switching means, the control means (100) for moving the rotational speed of the trunnion shaft (3) of the hydraulic continuously variable transmission (1) at a rotational speed lower than that during traveling on the road. A work vehicle characterized by being provided.   An accelerator lever (31) for controlling the engine speed of the work vehicle and the trunnion shaft (3) of the hydraulic continuously variable transmission (1) is provided in the vicinity of the steering handle (11) for steering the work vehicle. The work vehicle according to claim 1, wherein:

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