JP2009083612A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle, safely traveling when auto-cruise is set to travel and released, and the vehicle again returns to auto-cruise traveling. <P>SOLUTION: In this working vehicle, a continuously variable transmission, a second stepped transmission and a first stepped transmission are provided in a power transmission passage of a traveling device. The working vehicle includes: an auto-cruise switch, which stores a variable speed position of the continuously variable transmission, and the shift stages of the second stepped transmission and the first stepped transmission at that time as auto-cruise conditions on turning on in the process of forward traveling and controls to maintain the auto-cruise conditions; and an auto-cruise return switch for returning to traveling under the preceding auto-cruise conditions on turning on after the auto-cruise conditions are released, wherein the return to the auto-cruise speed by operating the auto-cruise return switch is performed only under the condition that the shift stages of the second stepped transmission and the first stepped transmission are not changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work vehicle, and more particularly to auto-cruise control that keeps a traveling speed constant.

A specific work vehicle often performs work while maintaining a constant traveling speed, and so-called auto-cruise control that maintains traveling at a constant speed is employed.
For example, Japanese Patent Application Laid-Open No. 2006-83996 describes a technique in which, in a combine, when the auto cruise set switch is turned on while the speed increasing pedal is depressed, the current travel speed is maintained as the auto cruise speed. Has been.

  In this technique, when a deceleration pedal is provided and the deceleration pedal is depressed, the auto-cruise speed is released and the vehicle decelerates. However, when the deceleration pedal is depressed, the speed returns to the auto-cruise speed.

Japanese Laid-Open Patent Publication No. 9-13428 discloses a technology for auto-cruise control that keeps the engine speed and the speed change position of the continuously variable transmission constant so as to keep the traveling speed constant as a traveling transmission for a wheel loader. It is.
JP 2006-83996 A Japanese Patent Laid-Open No. 9-13428

  Since a diesel engine with a narrow rotational speed range is used, the hydraulic continuously variable transmission and the multi-speed stepped transmission can be powered from the engine to the traveling device so that the traveling speed can be widely changed even if the engine speed is constant. It is provided in the transmission system. In this configuration, when the shift position of the stepped transmission is changed in the configuration in which the shift position of the hydraulic continuously variable transmission is kept constant and the auto-cruise speed is changed, the actual traveling speed is changed according to the shift stage. Therefore, if the stepped transmission is set to a high gear position during traveling in the auto-cruise state, the actual traveling speed becomes high and dangerous.

  Therefore, in the present invention, in a work vehicle that employs auto-cruise control that maintains the shift position of the hydraulic continuously variable transmission and maintains the auto-cruise speed, the auto-cruise is once released after the auto-cruise is set and traveled. It is an object of the present invention to prevent the actual traveling speed from changing in advance to the auto-cruising speed even when the stepped transmission is shifted when returning to the auto-cruising traveling.

The present invention takes the following technical means in order to solve the above-described problems.
That is, according to the first aspect of the present invention, the work vehicle in which the continuously variable transmission (1) and the stepped transmission (2, 3) are provided in the power transmission path of the traveling device (5) is turned on during forward traveling. Thus, the auto-cruise switch that stores the speed change position of the continuously variable transmission (1) and the speed of the stepped transmission (2, 3) at that time as auto-cruise conditions and controls to maintain the auto-cruise conditions. (6) and an auto-cruise return switch (7) for returning to traveling under the previous auto-cruise condition again after canceling the auto-cruise condition, and returning to the auto-cruise speed by operating the auto-cruise return switch (7) Is a work vehicle characterized in that the stepped transmission (2, 3) is performed under the condition that the gear position is not changed.

  In this configuration, after the automatic cruise is released, if the stepped transmission (2, 3) is in a position other than the gear position at the time when the automatic cruise switch (6) is pressed, the automatic cruise return switch (7) is The auto-cruise speed will not be reached even if the button is pressed, preventing the vehicle from traveling at an actual speed other than the auto-cruise setting speed in advance.

According to a second aspect of the present invention, there is provided the work vehicle according to the first aspect, wherein the operation by the auto cruise return switch (7) is configured to be accepted during forward traveling.
With this configuration, the auto-cruise return switch (7) does not become auto-cruise during stoppage or reverse travel, and the auto-cruise return switch (7) functions during forward travel. become.

  According to the first aspect of the present invention, when the work speed reaches the optimum speed on the work vehicle, the auto-cruise switch is set to the auto-cruise speed by pressing the auto-cruise switch (6) in order to maintain the traveling speed. Speed is maintained and driving is easier.

  When the same work is repeated again after the work is interrupted, when the auto-cruise return switch (7) is pressed, the vehicle starts traveling at the previous auto-cruise speed, so that the work can be resumed quickly. At that time, if the stepped transmission (2, 3) is in a speed other than the speed before the work interruption, the auto-cruise return switch (7) does not work, so that the vehicle travels at a speed other than the prior auto-cruise speed. There is no safety.

  According to the second aspect of the present invention, since the auto cruise return switch (7) operates and the auto cruise speed is set only when the aircraft is traveling forward, there is no drastic change in the travel speed, which is safe.

Next, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, as shown in FIGS. 1 and 2, the work vehicle is a multipurpose work vehicle, and a traveling device 5 including left and right front wheels 50 and left and right rear wheels 51 is supported on a monocoque frame so as to be steerable. The structure of the tractor is reversed in the front-rear direction, that is, the engine 10 is disposed at the rear of the fuselage, and the transmission 52 is disposed at the front of the fuselage. A control unit 53 is formed at the front part of the machine body, a loading platform 54 is formed at the rear part, a front PTO shaft 55 is provided at the front part of the machine body as power for the work machine, and a vehicle height detection mechanism 56 is suspended in the middle position of the machine body. Constitute.

  As shown in FIG. 3, the steering portion 53 is provided with a steering handle 58 on the steering portion 53. The forward / backward movement lever 16 is provided on the left side of the handle column 57, and the accelerator is located on the right side of the base of the handle column 57. Steering means such as a pedal 17 and a brake pedal 18 are arranged on the left side.

  FIG. 4 shows the main speed change lever 13, and by rotating the main speed change lever 13 from the center N of the speed change groove 59 to the front H or the rear L, the gear sub-transmission device 3 in the transmission 52, which will be described later, is moved to the high speed stage. Alternatively, when shifting to a low speed and pressing a high speed switch 15a or a low speed switch 15b provided on the head of the grip 13a of the main transmission lever 13, the high speed or low speed of the hydraulic transmission 2 in the transmission 52 is turned on. ing.

  In the transmission 52, a continuously variable transmission (hereinafter referred to as “HST”) 1, a hydraulic transmission (hereinafter referred to as “second auxiliary transmission”) 2, and a gear auxiliary transmission (hereinafter referred to as “first auxiliary transmission”). 3) are arranged in series to transmit power to the front and rear wheels 50, 51 and the front PTO shaft 50.

  When the forward / reverse lever 16 is operated, the HST 1 is shifted forward or backward, when the accelerator pedal 17 is depressed, the HST 1 is shifted to the acceleration side, and when the brake pedal 18 is depressed, the disc brakes of the front and rear wheels 50 and 51 are operated. At the same time, the trunnion shaft of the variable hydraulic pump of HST1 is returned to neutral, and the output from the quantitative hydraulic motor of HST1 is stopped. Further, when the accelerator pedal 17 and the brake pedal 18 are depressed simultaneously, the accelerator pedal 17 is prioritized and the disc brake is operated.

  Various work machines are connected to the front PTO shaft 55 so that multipurpose work can be performed. For example, a road cleaning machine is provided to perform road cleaning, a lawnmower is attached to perform lawn mowing work, or a snow scraper is provided to perform snow removal work.

FIG. 5 is a diagram showing a transmission mechanism in the transmission 52 that transmits power from the engine 10 to the traveling device 5.
The output shaft rotation of the engine 10 is first transmitted to the HST 1 through the speed increasing gear set 45, and the speed change output shaft is continuously shifted from forward to reverse. The output from the constant speed output shaft of the HST 1 is transmitted to the PTO shaft 49 via the gear transmission 47 and the clutch 48, and drives the front PTO shaft 55 or the mid PTO shaft 60 provided at the lower center of the machine body. The output from the transmission output shaft of the HST 1 is transmitted to the second auxiliary transmission 2 via the gear set 46, and is shifted between high speed and low speed by the second auxiliary transmission 2, and further neutralized by the first auxiliary transmission 3. The speed is changed to low speed and high speed, and the front wheel 50 is driven and the rear wheel 51 is also driven through the clutch 61.

  Therefore, the shifting of the traveling device 5 is continuously variable at each shift speed by a total of four speeds of the high and low two-stage shift of the second auxiliary transmission 2, the high and low two-stage shift of the first auxiliary transmission 3, and the continuously variable transmission of HST1. Will be shifted. The first subtransmission 3 and the second subtransmission 2 correspond to the stepped transmission of the present invention. The stepped transmission may be a gear transmission having four or more stages. good.

  Further, since it is dangerous to start the engine with the front PTO shaft 55 being driven, that is, with the clutch 48 engaged, a sensor for detecting whether the clutch 48 is engaged is provided so that the engine will not start if the clutch is engaged. Like that. This safety measure prevents the engine from starting when the PTO shaft is driven even in the case of external driving in which the PTO shaft is driven by a separate hydraulic pump.

FIG. 6 is a control block diagram showing input / output of control signals of the microcomputer 12 that controls the transmission.
An acceleration / deceleration signal of HST1 is output from the accelerator pedal 17, the microcomputer 12 rotates the trunnion shaft of HST1, and the rotational position of the trunnion shaft is input to the microcomputer 12.

From the main transmission lever 13, the gear position of the first sub-transmission device 3 is instructed, the microcomputer 12 shifts to the gear position instructing the first sub-transmission device 3, and the actual gear position is input to the microcomputer 12.
From the high / low switch 15, a high speed or low speed gear stage is instructed to the second auxiliary transmission device 2, the microcomputer 12 shifts to the gear stage instructing the second auxiliary transmission device 2, and the actual gear stage is sent to the microcomputer 12. Entered.

  The forward / reverse lever 16 instructs the HST 1 to move forward, backward or neutral. The microcomputer 12 moves the trunnion shaft of the HST 1 forward, backward or neutral according to the instruction, and the rotation position of the trunnion shaft is input to the microcomputer 12. The accelerator switch 14 sets the rotation of the engine 10 to the rated rotation speed, and the rotation speed is input to the microcomputer 12 from the engine 10 side. The brake pedal 18 outputs a braking signal for the disc brake 8, and the microcomputer 12 brakes the disc brake 8.

  The auto-cruise switch 6 is provided in the control unit 53. When the auto-cruise switch 6 is pressed during forward travel, the shift position of the HST1, the shift stage of the second auxiliary transmission 2, and the shift stage of the first auxiliary transmission 3 are set. And the rotational speed of the engine 10 is stored in the memory 19 and controlled under this storage condition to maintain the traveling speed. However, if the second sub-transmission device 2 is high speed and the first sub-transmission device 3 is high speed, the traveling speed is too high.

  The auto-cruise state is canceled by pressing the auto-cruise switch 6 again, but the brake pedal 18 is depressed, the main speed change lever 13 is operated to change the gear position of the first sub-transmission device 3, and the vehicle moves forward and backward. It is released when the lever 16 is operated or the high / low switch 15 is pressed to shift the second auxiliary transmission.

  To return to the pre-automatic cruise state again, the cruise return switch 7 may be pushed during forward traveling. Then, the HST 1 is shifted to the control condition stored in the memory. At that time, if the shift stage of the first auxiliary transmission 3 and the second auxiliary transmission 2 is different from the shift stage at the previous auto-cruise setting, the auto cruise It will not be in a state. In order to set the auto-cruise state under the current driving conditions, the auto-cruise switch 6 may be pushed again.

FIG. 7 is a flowchart of auto-cruise control.
If the auto-cruise switch 6 is turned on in step S2 while the vehicle is traveling in step S1, auto-cruise conditions such as the speed of the first auxiliary transmission 3 and the second auxiliary transmission 2 and the rotational speed of the engine 10 are determined in step S3. In step S4, the current rotation position of the trunnion shaft of the HST1, that is, the shift position is held, and the automatic cruise traveling is performed.

  During auto cruise driving, the brake pedal 18 is depressed in step S5, the forward / reverse lever 16 is switched in step S6, and the high speed switch 15a or the low speed switch 15b of the high / low switch 15 is turned on in step S7. If there is an operation to perform, or if there is a shift operation of the main shift lever 13 in step S8, the automatic cruise traveling is canceled in step S9.

  Then, after arbitrarily changing or stopping the traveling speed, when the auto-cruise return switch 7 is turned on in step S10, the first auxiliary transmission device 3 and the second auxiliary transmission device 2 store in step S4 in step S11. If the conditions are the same and the forward / reverse lever 16 is on the forward side in step S12, the vehicle returns to auto cruise in step S13. If there is a change in the first auxiliary transmission 3 and the second auxiliary transmission 2 or the forward / reverse lever 16 is other than forward, the automatic cruise is not performed in step S14.

  The above auto-cruise control is performed in a predetermined output range of engine speed, for example, 1800 rpm to 2800 rpm. However, if the traveling load increases due to climbing or the like, the engine speed may be 1800 rpm or less. The stepped transmissions 2 and 3 are also switched to a low speed to increase the driving torque of the traveling device. For example, the first transmission 3 or the second transmission 2 is shifted down from a high speed to a low speed. In this case, the auto cruise control is canceled.

8 and 9 show the mounting structure of the accelerator pedal 17.
In the configuration of FIG. 8, the accelerator pedal 17 is attached to the mounting base 26 obliquely with a pin 33 on the upper surface of the floor plate 32, and the mounting plate 21 connected to the trunnion shaft rotating portion of the HST 1 by the wire 20 The accelerator pedal 17 and the mounting plate 21 are connected to each other by a connecting rod 23.

  The attachment plate 21 is provided with three connection holes 24 for connecting the connection rods 23, and the position of the connection rods 23 can be changed to change the tilt angle of the accelerator pedal 17. The running speed can be changed greatly. The accelerator pedal 17 hits the stopper bolt 25 and reaches the depression limit.

  The configuration of FIG. 9 is substantially the same as that of FIG. 8, and the accelerator pedal 17 is attached to the mounting base 27 obliquely with a pin 34 on the upper surface of the floor plate 32 and is connected to the trunnion shaft rotating portion of the HST 1 with a wire 20. Is pivotally supported on the pivot shaft 29 by the lower surface of the floor plate 32, and the accelerator pedal 17 and the mounting plate 30 are coupled by the coupling rod 28.

  The attachment plate 30 is provided with three connection holes 31 for connecting the connection rod 28 at different distances from the pivot shaft 29, and the same depression angle of the accelerator pedal 17 is obtained when the hole position for attaching the connection rod 28 is changed. Thus, the responsiveness is changed by changing the movement of the mounting plate 29. A return spring 35 is provided between the pin 37 to which the wire 20 of the attachment plate 30 is attached and the floor plate 32, and a plurality of attachment holes 36 on the floor plate 32 side are provided to adjust the return tensile force. Yes.

  FIG. 10 shows a drive unit of the trunnion shaft 40 for shifting the HST 1. The fan gear 41 fixed to the trunnion shaft 40 meshes with the drive gear 43 fixed to the output shaft of the motor 42, and the drive gear is driven by driving the motor 42. The trunnion shaft 40 is rotated via the fan 43 and the fan-shaped gear 41 so as to shift forward, neutral, and reverse. In order to store the rotational neutral position of the motor 42 in the microcomputer 12, the trunnion shaft 40 is stored at the stage of assembly. An adjustment bolt 44 that abuts the fan-shaped gear 41 at a position where the HST 1 is neutral is set up, and the motor 42 is rotated after assembly to turn the fan-shaped gear 41 against the adjustment bolt 44. Then, the adjustment bolt 44 is removed.

Overall plan view of the multi-purpose work vehicle of this embodiment Overall side view of the multi-purpose work vehicle of this embodiment Partial perspective view of multi-purpose work vehicle Partially enlarged perspective view of a multi-purpose work vehicle Power transmission diagram of multi-purpose work vehicle Control block diagram Flow chart of control Partially enlarged perspective view of a multi-purpose work vehicle Partially enlarged perspective view of a multi-purpose work vehicle Partial enlarged plan view of a multi-purpose work vehicle

Explanation of symbols

1 Continuously variable transmission (HST)
2 Stepped transmission (second auxiliary transmission)
3. Stepped transmission (first auxiliary transmission)
5 Traveling device 6 Auto cruise switch 7 Auto cruise return switch

Claims (2)

  In a work vehicle in which the continuously variable transmission (1) and the stepped transmission (2, 3) are provided in the power transmission path of the traveling device (5), the continuously variable transmission ( 1) The shift position of the stepped transmission (2, 3) is stored as an auto-cruise condition, and the auto-cruise switch (6) is controlled so as to maintain the auto-cruise condition, and the auto-cruise condition is canceled. After that, an auto-cruise return switch (7) that returns to traveling under the pre-auto cruise condition is provided again, and the return to the auto-cruise speed by operating the auto-cruise return switch (7) 3) A work vehicle characterized in that it is performed under the condition that the gear position is not changed.   The work vehicle according to claim 1, wherein the operation by the auto cruise return switch (7) is configured to be accepted during forward traveling.

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