JP2008055965A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle superior in auto cruise operability not requiring that restarting action of auto cruise after release of auto cruise is frequently performed. <P>SOLUTION: In the working vehicle, when an auto cruise switch 62 is turned ON/operated, auto cruising traveling becomes possible by retaining a turning angle of a trunnion shaft 16 by an electric motor 53 to a constant degree. During when the vehicle is advanced at auto cruise, the turning angle of the trunnion shaft 16a when it advances at auto cruise is memorized even when an advancement/retreating switch lever 57 is switched to neutral or a retreating side, and the trunnion shaft 16a is driven to the memorized turning angle of the trunnion shaft 16a if the advancement/retreating switch lever 57 is operated to an advancement side again. The operability of the grass cutting work that advancement/retreating is frequently repeated is better than it was. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

   The present invention relates to a traveling vehicle for work such as a tractor and a lawn mower provided with a hydrostatic continuously variable transmission.

  A working vehicle such as a lawn mower is provided with an auto-cruise mechanism that continuously travels at a constant vehicle speed during, for example, lawn mowing. This auto-cruise mechanism does not detect the vehicle speed and maintain it at the vehicle speed set by the control device, but the rotation angle of the speed change operation shaft (trunnion shaft) of a hydrostatic continuously variable transmission (hereinafter referred to as HST). Is maintained and controlled at a set angle.

The auto-cruise mechanism in the invention described in Japanese Patent Laid-Open No. 2006-125535 has a configuration in which when the auto-cruise switch is operated, the speed change operation shaft is rotated by an electric motor and set to a predetermined rotation angle to start the auto-cruise operation. is there.
JP 2006-125535 A

In the invention described in Patent Document 1, it is necessary to release the auto cruise by setting the forward / reverse switching lever to neutral or reverse, and to start the auto cruise again, it is necessary to press the auto cruise switch. However, in the case of a work that repeatedly moves forward and backward, such as a lawn mowing work, it is necessary to press the auto-cruise switch every time the vehicle moves forward, and the operation is very troublesome.
An object of the present invention is to provide a work vehicle having excellent auto-cruise operability that does not require frequent start operations of auto-cruise again after canceling auto-cruise.

The above-mentioned problem of the present invention is solved by the following means.
The invention according to claim 1 is a hydrostatic continuously variable transmission (16) having a speed change operation shaft (16a) for changing the output for shifting the vehicle speed to a forward position, a neutral position and a reverse position, respectively. A pedal-type shift operation tool (18) for causing the hydrostatic continuously variable transmission (16) to output to any one of the forward side, the neutral side and the reverse side via the shift operation shaft (16a); Manual forward / reverse switching means (57) for switching the shaft (16a) between the forward movement state and the reverse movement state, and forward / reverse movement for detecting whether the manual forward / reverse movement switching means (57) is in the forward movement position or the reverse movement position. Operation position detection means (57a, 57b), pedal depression position detection means (47) for detecting the depression position of the pedal type shifting operation tool (18), and forward / reverse operation position detection means (57a, 57b) Or, check the reverse operation position. Depending on the result, the speed change operation shaft (16a) is rotated forward or backward, respectively, and the speed change operation shaft (16a) is moved forward or backward according to the detection value of the pedal depression position detecting means (47). An actuator (53) for increasing or decreasing the output of the hydrostatic continuously variable transmission (16) by adjusting the amount of rotation to the side, and a speed change operation shaft according to the detected value of the pedal depression position detecting means (47) The actuator (53) that rotates (16a) to increase / decrease the output of the hydrostatic continuously variable transmission (16), and (a) the shift operation shaft (16a) is maintained at the set rotation angle to move forward. Vehicle speed control for driving and controlling the actuator (53) performed in the state, (b) when the traveling direction is switched to the reverse side during the vehicle speed control in the forward state, (a) before switching to the reverse side Vehicle speed control in the forward state The vehicle speed control for storing the speed operation shaft turning angle and the drive control of the actuator (53) according to the depression position of the pedal-type speed change operation tool (18), (c) When returning from the reverse drive state to the forward drive state again, (a ) Is a work vehicle equipped with a control device (48) for performing vehicle speed control including vehicle speed control for driving and controlling the actuator (53) so as to maintain the rotational angle of the speed change operation shaft (16a) stored in the vehicle speed control. is there.

  According to the first aspect of the present invention, the vehicle speed control of (a) is provided with auto-cruise setting means such as an auto-cruise switch, and the manual forward / reverse switching means (57) is traveling at the forward operation position. The auto cruise switch is turned on, and the rotation angle of the speed change operation shaft (16a) driven by the actuator (53) is kept constant according to the depression position of the pedal type speed change operation tool (18). In this way, the vehicle can be auto-cruising. However, since the auto-cruise traveling is performed only when the vehicle is moving forward, the control device (48) is configured not to accept the turning on of the auto-cruising switch when the vehicle moves backward or stops.

  According to a second aspect of the present invention, the work vehicle includes a work machine connected thereto, and further includes a PTO clutch (32) for controlling the drive of the work machine. The work vehicle according to claim 1, wherein the work vehicle is effective only when (32) is on.

  According to the first aspect of the present invention, the rotational angle of the speed change operation shaft (16a) when the vehicle is moving forward by auto-cruise is stored even when the shift position of the traveling vehicle is switched to the neutral or reverse side. Therefore, when the speed change position is operated to the forward side again, the speed change operation shaft (16a) is driven to the rotation angle set by the speed change operation shaft (16a) stored in the forward state. When frequently performing forward / reverse operation frequently, the lawn mowing work operability is improved as compared with the prior art without operating an auto cruise setting means such as an auto cruise switch every time the vehicle advances.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, for example, traveling control only when driving a working machine that performs lawn mowing work can be efficiently performed.

Embodiments of the present invention will be described below with reference to the drawings.
A side view of a multipurpose tractor 1 such as a riding lawn mower according to the present embodiment is shown in FIG. 1, and a plan view thereof is shown in FIG. The front and rear parts of the traveling vehicle body 2 are provided with front wheels 3, 3 and rear wheels 4, 4 respectively, a mower 6 for turf mowing is provided below the front part of the vehicle body frame 2, and a floor above the front part of the vehicle body 2 7, a steering column 8 is erected, and a handle 10 is provided above the column 8. A cockpit 11 is located behind the handle 10, and an engine 12 is mounted behind the cockpit 11.

In this specification, the left and right directions are referred to as the left and right directions, respectively, and the front and rear directions are referred to as the front and rear, respectively.
The cooling fan of the engine 12 is driven by engine power, and the radiator 64 is installed obliquely on the vehicle body. Thereby, the installation height can be reduced without reducing the cooling capacity of the radiator 64.

The output shaft of the engine 12 is connected to the input shaft of the transmission in the transmission case 15, the rotational power of the engine 12 is changed by the transmission, and the shifted driving power is transmitted to the front and rear wheels 3 and 4 via the transmission mechanism. To communicate.
Further, a mower drive shaft (not shown) protrudes from the front surface of the transmission case 15, and a lawn mowing cutter in the mower 6 is rotated by the drive shaft.
In addition, the mower 6 of the multipurpose tractor of the present embodiment is not limited to the front of the vehicle body, but may be arranged at the center and the rear.

FIG. 3 shows a power transmission configuration diagram of the multipurpose tractor.
The HST 16 provided adjacent to the transmission case 15 is linked to the HST input shaft 19 via the main clutch 17 in the clutch housing, and is switched from forward to reverse by a shift pedal (pedal type shift operating tool) 18. In addition, through the interlocking by these continuously variable transmissions, the differential gear mechanism of the front wheels 3, the output shaft to the rear wheels 4 and the like are transmitted to the auxiliary transmission 21. The output from the differential gear mechanism differential device 30 is transmitted to the front wheel 3 via the planetary reduction device 28.

  The HST 16 connects the fixed displacement pump 23 and the variable displacement motor 24 with a closed hydraulic circuit 25, and sets the inclination angle of the swash plate 22 of the fixed displacement pump 23 (the rotation angle of the trunnion shaft 16 a) of the transmission pedal 18. By adjusting by stepping on, the amount of oil discharged from the fixed displacement pump 23 can be changed, the output rotation of the output shaft 26 by the variable displacement motor 24 can be continuously variable, and the output can be switched between forward and reverse.

The power from the HST output shaft 26 is shifted by the high and low three-stage auxiliary transmission 21 and extracted to the traveling shaft 27, and the differential device 30 for transmission from the traveling shaft 27 to the front wheel 3, the rear wheel transmission shaft 31, and the rear Power is taken out to the differential device 33 for transmission to the wheel 4. The transmission of the rear wheel transmission shaft 31 is turned on and off by a rear wheel drive gear 34 for four-wheel drive.
Further, the power is switched from the PTO shaft 39 to the front PTO input shaft 36 or the mid or rear PTO shaft 40 through the PTO drive hydraulic clutch 32 from the output shaft 29 provided in the HST pump 23 and taken out.

  Next, the HST 16 is provided adjacent to the mission case 15 as shown in a side view of the HST mounting portion in FIG. 4, a plan view of the HST mounting portion in FIG. 5, and a rear view of the HST mounting portion in FIG. The rotational power is input to the traveling mission system in the case 15. The HST mounting base 70 is formed as a single plate as shown in the figure, and the plate plane is arranged in the vertical direction at a position away from the HST 16 and the transmission case 15 outside the fuselage. The mounting bolt 71 and the collar 72 are supported.

  An electric motor 53 for controlling the operation of the trunnion shaft 16 a of the HST 16 is mounted on the base 70 so as to be positioned between the mounting base 70 and the transmission case 15 inside the mounting base 70. The operation device 73 of the trunnion shaft 16a interlocked with the speed change pedal 18 includes an operation shaft 73a and an operation gear 73b. The operation shaft 73a passes through the mounting base 70 and is supported by a bearing. The other end outside the machine body is pivotally attached to the operation gear 73b.

  The trunnion shaft 16a extends from the HST 16 to the outside of the machine body, penetrates the mounting base 70, is supported by the bearing to the outside of the machine body of the base 70, and has a transmission gear 75a attached to the tip portion. In this case, the trunnion shaft 16a is supported by the mounting base 70 while maintaining a parallel state with the operation shaft 73a on the electric motor 53 side, and a transmission gear 75a having a large diameter is provided at the tip of the trunnion shaft 16a. The gear 75a and a small-diameter operation gear 73b of the operation shaft 73a are provided in mesh with each other, and the operation force output from the electric motor 53 is transmitted to the trunnion shaft 16a.

  The electric motor 53 is driven in the forward or reverse direction according to the depression position of the shift pedal 18 so as to be able to shift. For example, the drive command signal is output to the electric motor 53 in accordance with the detection angle by the HST pedal depression position detection sensor (pedal position sensor) 47 (FIG. 7) configured by a potentiometer that detects the depression angle of the shift pedal 18. is there. The electric motor 53 is configured to return to the neutral position while being automatically driven in the forward or reverse direction when the foot is released from the shift pedal 18.

  The shift pedal 18 can only be stepped in the forward direction. When the shift pedal 18 is depressed with the forward switch 57a turned on by operating the forward / reverse switching lever 57, the trunnion shaft 16a rotates in the forward direction. Interlocked. At this time, the depression amount of the speed change pedal 18 is detected by the pedal position sensor 47, and the rotation amount of the trunnion shaft 16a in the forward rotation direction is determined according to the detected value. Similarly, when the shift pedal 18 is depressed with the reverse switch 57b being turned on by operating the forward / reverse switching lever 57, the trunnion shaft 16a is rotationally interlocked in the reverse direction. The amount of depression of the speed change pedal 18 at this time is detected by the pedal position sensor 47, and the amount of rotation of the trunnion shaft 16a in the reverse rotation direction is determined according to the detected value.

  As described above, the operating device 73 for the electric motor 53 and the trunnion shaft 16a is attached to the mounting base 70 that is provided on the outer side of the machine body from the HST 16 and the transmission case 15, so that the speed change operation of the HST 16 can be performed. Thus, an HST operation member that is small and easy to assemble can be obtained, and the HST 16 can be sufficiently mounted on a small tractor.

  Further, a trunnion shaft 16a position sensor (trunion shaft 16a position detecting means) 76 is attached below the trunnion shaft 16a to detect the rotational angle position of the trunnion shaft 16a. That is, the L-shaped pin 76a provided integrally with the trunnion shaft 16a extends from the potentiometer 76b side and engages with the engaging portion 76c formed at the tip thereof to form a U-shape, thereby connecting the angle change of the trunnion shaft 16a to the potentiometer 76b. It is the structure to do.

  With this configuration, the rotation angle of the trunnion shaft 16a can be detected, operation confirmation such as whether the trunnion shaft 16a is operating normally or returning to the neutral position, and rotation by the electric motor 53 can be corrected.

  Further, a trunnion arm 77 is provided extending upward from the trunnion shaft 16a, a pin 77a is provided on the upper portion of the trunnion arm 77, and a length formed on a plate 78 having a pair of operating rods 79F and 79R attached to the front and rear. The pin 77a is locked in the hole 78a. As shown in FIG. 4, the operating rods 79F and 79R are configured to be connected to the brake pedal 82 via operation wires 80F and 80R respectively connected to the ends thereof.

  Since it is configured as described above, when the brake pedal 82 is not operated, the trunnion arm 77 can follow the transmission gear 75a within the range allowed by the long hole 78, while the brake pedal 82 is stepped on. When the electric motor 53 breaks down, the safety of the HST 16 can be ensured.

  In the HST 16 having the above-described configuration, the neutral reference position of the trunnion shaft 16a changes due to a change over time of the mechanism for detecting the set position of the trunnion shaft 16a due to the very narrow neutral width of the trunnion shaft 16a. Even if the vehicle is positioned in the neutral position, there is a problem that the vehicle does not stop.

  Therefore, in the configuration in which the shift pedal position of this embodiment is detected by the HST (shift) pedal depression position detection sensor 47 and the trunnion shaft 16a is driven by the electric motor 53, a vehicle speed sensor 85 (FIG. 7) is further used as a sensor for detecting the vehicle speed. ), And when the vehicle speed sensor 85 detects a slight forward / backward movement of the vehicle when the shift pedal 18 is in the neutral position, the trunnion shaft 16a is driven at a very low speed by driving the trunnion shaft 16a. The controller 48 performs control to return the shaft 16a to the neutral position. When the trunnion shaft 16a returns to the neutral position, the controller 48 detects the position by the trunnion shaft 16a position sensor 76, and an automatic correction function for automatically writing the detected value to the nonvolatile memory is provided. There is no need to perform an operation for returning the trunnion shaft 16a to the neutral position.

  In order to move the trunnion shaft 16a at a slow speed, for example, a pulse is output at a very short cycle of, for example, 10 msec by PWM (Pulse Width Modulation) output, and the electric motor 53 for operating the trunnion shaft 16a is operated at a slow speed.

FIG. 7 shows a block diagram of the operation control of the HST trunnion shaft 16a of the present embodiment.
The controller 48 is configured to control the operation of the electric motor 53 for operation of the trunnion shaft 16a and the like by an input from a potentiometer type HST pedal depression position detection (pedal position) sensor 47 that detects the depression position of the shift pedal 18. .
Further, when a forward / reverse switching lever 57 provided at the operator's hand such as the handle column 8 is moved forward or backward, a contact member (not shown) integrated with the lever 57 presses the forward switch 57a or the reverse switch 57b, and by detection thereof. By switching the direction of rotation of the trunnion shaft 16a between forward and reverse and depressing the shift pedal 18 in this state, the machine body is moved forward or backward at a speed corresponding to the depression amount of the shift pedal 18.

  Further, when the auto cruise switch 62 is provided in the operation portion and the auto cruise switch 62 is turned on and operated, and the shift pedal 18 is depressed more than a predetermined angle and the forward vehicle speed exceeds, for example, 1 km / hour, the electric motor The rotation angle of the trunnion shaft 16a by 53 is kept constant. In this way, the vehicle can be auto-cruising. However, since the auto-cruise traveling is performed only when the vehicle is moving forward, the controller 48 is configured not to accept the auto-cruise switch 62 when the vehicle is moving backward or stopped.

The controller 48 also stores the turning angle of the trunnion shaft 16a when the vehicle is moving forward by auto-cruising even when the vehicle is moving forward by auto-cruising and the forward / reverse switching lever 57 is switched to the neutral or reverse side. When the forward / reverse switching lever 57 is operated to the forward side again, the trunnion shaft 16a is driven at the stored rotation angle of the trunnion shaft 16a.
In this way, for example, in the case of a work that repeats forward and backward movements, such as a lawn mowing work, the operability of the mowing work is improved as compared with the prior art without pressing the auto-cruise switch 62 each time the vehicle moves forward.

  When the auto cruise switch 62 is not turned on, the controller 48 moves forward or backward at a traveling speed depending on the rotation angle of the trunnion shaft 16a according to the depression position of the shift pedal detected by the position sensor 47 of the shift pedal 18. .

  These control flow diagrams are shown in FIG. In the flowchart of FIG. 8, after the auto-cruise switch 62 is turned on in step S1, auto-cruise control is started for the first time when the auto-cruise switch 62 changes from off to on again in step S2. This is because the auto-cruise switch 62 is a normally open switch, and therefore the start and end of auto-cruise is determined by the on / off change of the switch 62.

  In step S10, when the forward / reverse switching lever 57 is operated to the forward side during auto-cruising, the auto-cruise traveling is continued as it is, and in step S11, the forward / backward switching lever 57 is operated to the reverse side during auto-cruising. Then, the auto-cruise is stopped and the rotation angle of the trunnion shaft 16a is positioned at the reverse travel position corresponding to the shift pedal 18.

  Further, in the control flow of one embodiment of the present invention shown in FIG. 9, after the forward / reverse switching lever 57 is operated to the neutral or reverse side, the switching lever 57 is switched again to the forward side to return to the auto cruise vehicle speed. The control is performed only when the PTO drive hydraulic clutch 32 detected by the PTO clutch sensor 35 is engaged.

  This is because, when the forward / reverse switching lever 57 is set to the neutral or reverse side and then set to the forward side again, it is necessary to avoid starting forward at the auto cruise vehicle speed while driving on the road. It is. Therefore, in the control using the flowchart shown in FIG. 9, traveling safety can be improved by limiting the return to the auto cruise vehicle speed only during work traveling using the work implement.

In the travel control of one embodiment of the present invention, when the auto cruise vehicle speed is set, the vehicle speed set by the depression operation angle (pedal position) of the shift pedal 18 as shown in the graph of FIG. 10 and the flowchart of FIG. When the vehicle speed exceeds a predetermined auto-cruise vehicle speed (for example, 1 km / h), the trunnion shaft 16a may be rotated so that the vehicle speed is set at the depression position of the shift pedal 18.
At this time, when the vehicle speed set at the depression position of the shift pedal 18 becomes equal to or lower than the auto-cruise vehicle speed, the auto-cruise traveling is resumed.

  When it is desired to change the vehicle speed during auto-cruise traveling, the conventional control configuration is adopted in which auto-cruise traveling control is canceled when the shift pedal 18 is operated. However, auto-cruising is canceled and auto-cruising is again performed. Operations such as setting the vehicle speed by pressing the switch 62 are troublesome.

  However, according to the control shown in FIG. 10 and FIG. 11 described above, the vehicle speed is changed during auto-cruise traveling by giving priority to the vehicle speed set by the shift pedal 18 over the auto-cruise vehicle speed while traveling at a vehicle speed exceeding the auto-cruise vehicle speed. The vehicle speed can be changed without canceling the auto-cruise traveling control even if it is desired. For this reason, the degree of freedom of vehicle speed control during auto-cruising has become higher than before.

  Further, in the travel control of one embodiment of the present invention, when the auto cruise vehicle speed is set, the shift pedal 18 is at a position other than the neutral position (the foot is released from the pedal) as shown in the graph of FIG. 12 and the flowchart of FIG. When the vehicle is operated, the auto-cruise control is canceled, the rotation angle of the trunnion shaft 16a is changed so that the vehicle speed corresponds to the depression position of the shift pedal 18 shown by the solid line in FIG. 12, and the shift pedal 18 is set to the neutral position. If there exists, it is the structure which restarts the auto cruise control shown by the broken line of FIG.

  At this time, since the auto-cruise traveling control is cancelled, as in the embodiment described with reference to FIGS. 10 and 11, a complicated operation such as pressing the auto-cruise switch 62 again to change the vehicle speed during auto-cruising. As a result, the degree of freedom in controlling the vehicle speed during auto-cruising has increased.

  Next, FIG. 14 shows a side view of the speed change pedal according to one embodiment of the present invention, and FIG. 15 shows a schematic diagram of a mechanical interlocking mechanism between the electromagnetic clutch 66 for turning on and off the electric motor 53 and the HST trunnion shaft 16a. FIG. 16 shows a control block diagram of this embodiment.

  In the present embodiment, the trunnion shaft 16a is rotated by the electric motor 53, and the operation amount of the electric motor 53 is changed corresponding to the depressed position of the shift pedal 18, and the electric motor is operated when the shift pedal 18 is in the neutral position. 53 is turned off, and the trunnion shaft 16a is returned to the neutral position by a mechanical interlocking mechanism that operates when the electric motor 53 is turned off.

  In this embodiment, a pedal position sensor 47 that detects the depression position of the shift pedal 18 and a pedal neutral position detection sensor 63 that is turned off when the shift pedal 18 is in the neutral position are provided, and the rotation of the electric motor 53 is controlled by the trunnion shaft 16a. An electromagnetic clutch 66 is provided for transmission to the arm 66a, and an arm 65 whose base is rotatably supported by an appropriate member of the traveling vehicle body 2 is engaged with a bearing 66a1 provided on the arm 66a interlocking with the operation of the electromagnetic clutch 66. Furthermore, a spring 68 whose end is supported by an appropriate member of the traveling vehicle body 2 is connected to the tip of the arm 65.

  With the above configuration, the arm 66a is always urged so as to be held at the position shown in the figure by the bearing 66a1 and the spring 68. As described above, the arm 66a is held at the predetermined position shown in the figure when the electromagnetic clutch 66 is turned off, and the arm 66a and the trunnion shaft 16a are connected by the link 67, and the arm 66a turns off the electromagnetic clutch 66. When in the predetermined position, the trunnion shaft 16a is also held in the neutral position.

  When the pedal neutral position detection sensor 63 is off because the shift pedal 18 is in the neutral position, a signal corresponding to the pedal neutral position detection sensor 63 being off is input to the controller 48, and the controller 48 When the electromagnetic clutch 66 is turned off by this signal input and the rotational transmission force of the electric motor 53 is cut off, the arm 66a is held at a predetermined position shown in FIG. At this time, the link 67 returns the trunnion shaft 16a to the neutral position by the tension of the spring 68.

Further, when the shift pedal neutral position detection sensor 63 is on (when the shift pedal 18 is not in the neutral position), when the electromagnetic clutch 66 is turned on to operate the electric motor 53, the rotational power of the electric motor 53 is increased. Is configured to overcome the tension of the spring 68 and drive the trunnion shaft 16a.
A flowchart of the above embodiment is shown in FIG.

  The pedal position sensor 47 activates the electric motor 53 after the controller 48 turns on the electromagnetic clutch 66 in accordance with the depression position of the speed change pedal 18 detected by the sensor 47, thereby adjusting the rotation angle of the trunnion shaft 16a. The vehicle speed can be changed by setting to a predetermined value.

The conventional turning mechanism of the trunnion shaft 16a, which is performed via a mechanical interlocking mechanism in accordance with the depression position of the shift pedal 18, has a large load when the shift pedal 18 is depressed, and causes an increase in operator fatigue during long-time work. It was.
However, according to this embodiment, since the trunnion shaft 16a is moved by the electric motor 53, the load when the shift pedal 18 is depressed can be reduced. Further, since the portion lacking in reliability because the trunnion shaft 16a is moved only by the electric motor 53, when the shift pedal 18 is returned to the neutral position, the electromagnetic clutch 66 is turned off, and the mechanical structure including the arm 66a, the spring 68, the link 67, and the like. Since the trunnion shaft 16a is returned to the neutral position by the interlocking mechanism, the traveling stop operation of the vehicle can be performed by double stop operation control, so that safety is improved.

  In the configuration of the present embodiment, as shown in FIG. 16, the electromagnetic clutch 66 can be directly and electrically connected to and disconnected from the pedal neutral position detection sensor 63 without passing through the controller 48, so that the controller 48 has failed. Even at times, the electromagnetic clutch 66 can be reliably turned off and the vehicle can be stopped, and the safety is improved as compared with the configuration via the controller 48.

When the pedal neutral position detection sensor 63 or the pedal position sensor 47 detects the neutral position of the shift pedal 18 and the signal is input to the controller 48 in the configuration shown in FIGS. The vehicle may be stopped by giving priority to other signals by inputting this signal. For example, if the trunnion shaft 16a is not in the neutral position and only the pedal position sensor 47 indicates that the shift pedal 18 is in the neutral position, the electromagnetic clutch 66 is turned on and the trunnion shaft 16a is moved to the neutral position by the electric motor 53, that is, stopped. Move to position.
In this embodiment, even if one of the two sensors 47, 63 is out of order, the vehicle can be stopped, so that a fail-safe configuration is achieved and safety is improved.

  As a modification of the above embodiment, as shown in the flowchart of FIG. 18, a motor current sensor indicates that the trunnion position sensor 76, which is a sensor for detecting the position of the trunnion shaft 16a, is abnormal or the electric motor 53 is abnormal. If 69 detects, you may employ | adopt the structure which stops by turning off the output of the electromagnetic clutch 66 and turning off the drive output of the trunnion shaft 16a. Note that an abnormality of the trunnion position sensor 76 cannot be detected by the motor current sensor 69.

  The abnormality of the trunnion position sensor 76 is, for example, disconnection or short-circuit, and the trunnion position sensor 76 detects that the trunnion shaft 16a does not move from the neutral position even though the controller 48 can detect the output of the motor 53. It is.

The abnormality of the electric motor 53 is caused when the motor current detected by the motor current sensor 69 is equal to or less than a predetermined value. When these detection signals are transmitted to the controller 48, the controller 48 turns off the output of the electromagnetic clutch 66.
With the above configuration, even if the trunnion shaft 16a cannot be controlled, the vehicle can be stopped reliably, so that safety is improved.

  Further, when the output of the pedal neutral position detection sensor 63 is not zero (when the shift pedal 18 is not in the neutral position), the output of the electromagnetic clutch 66 is turned on, and at this time, the trunnion shaft 16a is in the depressed position of the shift pedal 18. The drive output of the trunnion shaft 16a is performed so that the corresponding rotation angle is obtained.

  As shown in the flowchart of FIG. 19, the time chart of FIG. 20, and the circuit diagram of FIG. 21, when the HST trunnion shaft 16 a is driven by the electric motor 53, the forward rotation relay 87 (the trunnion shaft) for rotating the trunnion shaft 16 a normally. A relay for connecting the electric motor 53 and the electrical rotation mechanism of the trunnion shaft 16a so as to rotate 16a in the forward direction and a reverse relay 88 for reversing the trunnion shaft 16a (reversing the trunnion shaft 16a in the forward direction). A relay for connecting the electric motor 53 and the electrical rotation mechanism of the trunnion shaft 16a) to the electric motor 53 and switching the forward / reverse direction of the electric motor 53, and then the forward rotation relay 87 or the reverse relay of the trunnion shaft 16a. In the configuration of energizing each of the 88 relay contacts 87a, 88a, the electric motor of the trunnion shaft 16a 3 until the predetermined number of times is reached after the key is turned on, via the drive output element 89 of the electric circuit for forward / reverse switching of the electric motor 53 and the electric circuit for driving output of the trunnion shaft 16a of the electric motor 53. When switching the forward / reverse switching electric circuit of the electric motor 53 to the electric motor 53 output stop circuit, the electric circuit for driving output of the trunnion shaft 16a is simultaneously with the switching. Turn off the output.

  This control is to prevent such troubles because if the forward relay 87 or the reverse relay 88 is not used for a long time, an oxide film is formed on the relay contacts 87a and 88a, resulting in poor contact. is there.

  If the relay contacts 87a and 88a are energized after switching the forward relay 87 or the reverse relay 88, arc discharge is eliminated at the relay contacts 87a and 88a, and the oxide film cannot be removed. When the power is applied to the relay contacts 87a and 88a, the contacts 87a and 88a are turned on in a state where voltage is applied to the relay contacts 87a and 88a, so that arc discharge occurs and the oxide film can be removed, resulting in poor contact of the relay contacts 87a and 88a. Can be prevented.

  In the embodiment shown in FIG. 22, the shift pedal 18 and the clutch 91 are not electrically connected, but are connected by a mechanical link mechanism 92, and the clutch 91 has the same mechanical link as that shown in FIG. In this configuration, the trunnion shaft 16 a is rotated via the mechanism 67. The clutch that was the electromagnetic clutch 66 in the configuration of FIG. 15 is the mechanical clutch 91 in the configuration of FIG.

  Accordingly, when the shift pedal 18 is depressed from the neutral position by a certain amount, the mechanical link mechanism 92 interlocked with the pedal 18 operates the mechanical clutch 91 to rotate the electric motor 53, and the rotational force of the electric motor 53 is mechanically affected. The trunnion shaft 16a is rotated by being transmitted to the link mechanism 67.

  A flowchart of this embodiment is shown in FIG. FIG. 24 discloses a configuration in which the mechanical link 94 between the automatic cruise shift pedal 18 and the trunnion shaft 16a is interlocked with the assistance of the assist motor 93.

  In the configuration similar to the configuration shown in FIG. 15, the position of the trunnion shaft 16 a can be kept constant by auto-cruise control by operating the shift pedal 18 with the assistance of the assist motor 93 in FIG. 24. At this time, the assist motor 93 is configured to pass a current for maintaining the depression position of the shift pedal 18 during auto-cruising. For example, by storing the actual vehicle speed, a constant vehicle speed is always maintained at a predetermined output of the assist motor 93 even when the vehicle speed for maintaining the depression position of the shift pedal 18 during auto-cruising tends to fluctuate on a slope. be able to. A flowchart of this embodiment is shown in FIG.

  The present invention can be used as a traveling vehicle for agricultural work such as a highly safe tractor.

It is a side view of the working vehicle (multipurpose tractor) for agricultural work of one Example of this invention. It is a top view of the work vehicle of FIG. It is a power transmission mechanism figure of the work vehicle of FIG. It is a side view of the HST attachment part of the working vehicle of FIG. It is a top view of the HST attachment part of the working vehicle of FIG. It is a rear view of the HST attachment part of the working vehicle of FIG. It is a HST trunnion shaft drive control block diagram of the work vehicle of FIG. 2 is a flowchart of drive control of an HST trunnion shaft in one embodiment of the work vehicle of FIG. 1. 2 is a flowchart of drive control of an HST trunnion shaft in one embodiment of the work vehicle of FIG. 1. It is a figure which shows the relationship between the position of the HST trunnion shaft which gives priority to the auto cruise control of one Example of the working vehicle of FIG. 1, and a shift pedal position. 2 is a flowchart of drive control of an HST trunnion shaft in one embodiment of the work vehicle of FIG. 1. FIG. 2 is a diagram illustrating a relationship between a position of an HST trunnion shaft and a shift pedal position during auto-cruise control and non-control of the embodiment of the work vehicle of FIG. 1. 2 is a flowchart of drive control of an HST trunnion shaft in one embodiment of the work vehicle of FIG. 1. It is a figure explaining arrangement | positioning of the detection sensor of the depression position of the speed-change pedal of one Example of the working vehicle of FIG. It is a block diagram which connects the HST trunnion axis | shaft and this trunnion drive part of one Example of the working vehicle of FIG. FIG. 2 is a drive control block diagram of an HST trunnion shaft of one embodiment of the work vehicle of FIG. 1. 2 is a flowchart of drive control of an HST trunnion shaft in one embodiment of the work vehicle of FIG. 1. It is a flowchart of the modification of the drive control of the HST trunnion shaft in the structure of FIG. 2 is a flowchart of drive control of an HST trunnion shaft in one embodiment of the work vehicle of FIG. 1. It is a figure explaining the timing which starts the drive output of the motor for a drive of the HST trunnion shaft from the key-on time in the flow of FIG. FIG. 20 is a drive output circuit diagram of an HST trunnion shaft drive motor for executing the flow of FIG. 19. It is a figure explaining the structure which connects the speed change pedal and clutch of one Example of the working vehicle of FIG. 1 with a mechanical link mechanism, and rotates a trunnion shaft. FIG. 23 is a flowchart for controlling driving of the HST trunnion shaft with the configuration of FIG. 22. It is a figure explaining the structure which connects the speed change pedal and trunnion shaft of one Example of the working vehicle of FIG. 1 by a mechanical link mechanism, and rotates a trunnion shaft. FIG. 25 is a flowchart for controlling driving of the HST trunnion shaft with the configuration of FIG. 24.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multipurpose tractor 2 Traveling vehicle body 3 Front wheel 4 Rear wheel 6 Moore 7 Floor 8 Steering column 10 Handle 11 Pilot seat 12 Engine 15 Mission case 16 HST
16a trunnion shaft 17 main clutch 19 HST input shaft 18 shift pedal 21 auxiliary transmission 22 swash plate 23 fixed displacement pump 24 variable displacement motor 25 closed hydraulic circuit 26 output shaft 27 travel shaft 28 planetary speed reducer 29 output shaft 30 differential device 31 Rear wheel transmission shaft 32 PTO drive hydraulic clutch 33 Differential device 34 Rear wheel drive gear 35 PTO clutch sensor 36 Front PTO input shaft 39 PTO shaft 40 Rear or mid PTO input shaft 47 HST pedal depression position detection sensor 48 Controller 53 Electric motor 57 Forward / reverse switching lever 57a Forward switch 57b Reverse switch 62 Auto cruise switch 63 Pedal neutral position detection sensor 64 Radiator 65 Arm 66 Electromagnetic clutch 66a Arm 67 Link
68 Spring 69 Motor current sensor 70 HST mounting base 71 Mounting bolt 72 Color 73 Operating device 73a Operating shaft 73b Operating gear 75a Transmission gear 76 Trunnion shaft position sensor (Trunnion shaft position detecting means)
76a L-shaped pin 76b Potentiometer 76c Engagement section 77 Trunnion arm 77a Pin 78 Plate 78a Long hole 79F, 79R Operating rod 80F, 80R Operation wire 82 Brake pedal 85 Vehicle speed sensor 87 Trunnion forward relay 88 Trunnion reverse relay 89 Trunnion drive output element 91 mechanical clutch 92 mechanical link mechanism 93 assist motor 94 link mechanism

Claims (2)

A hydrostatic continuously variable transmission (16) having a speed change operation shaft (16a) for changing an output for shifting the vehicle speed to a forward position, a neutral position and a reverse position;
A pedal-type transmission operation tool (18) for causing the hydrostatic continuously variable transmission (16) to output to any one of the forward side, the neutral side and the reverse side via the transmission operation shaft (16a);
Manual forward / reverse switching means (57) for switching the shift operation shaft (16a) between a forward state and a reverse state;
Forward / reverse operation position detecting means (57a, 57b) for detecting whether the manual forward / reverse switching means (57) is in the forward position or the reverse position;
Pedal depression position detecting means (47) for detecting the depression position of the pedal type shifting operation tool (18);
The shift operation shaft (16a) is rotated forward or backward according to the detection result of the forward or reverse operation position of the forward / reverse operation position detection means (57a, 57b), and the pedal depression position detection means Actuator (53) for adjusting the output of the hydrostatic continuously variable transmission (16) by adjusting the amount of rotation of the speed change operation shaft (16a) forward or backward according to the detected value of (47) When,
(A) Vehicle speed control for driving and controlling an actuator (53) that is moved forward while maintaining the speed change operation shaft (16a) at a set rotation angle;
(B) When the traveling direction is switched to the reverse side during the vehicle speed control in the forward state, the speed change operation shaft turning angle in the forward state in the vehicle speed control of (a) before switching to the reverse side. Vehicle speed control for driving and controlling the actuator (53) according to the depression position of the pedal-type speed change operation tool (18),
(C) When returning from the reverse state to the forward state again, the vehicle speed control for driving and controlling the actuator (53) so as to maintain the rotation angle of the speed change operation shaft (16a) stored in the vehicle speed control of (a). A work vehicle comprising a control device (48) for performing vehicle speed control. The work vehicle includes a work machine connected thereto, and further includes a PTO clutch (32) for driving and controlling the work machine,
The work vehicle according to claim 1, wherein the resumption of the vehicle speed control in (c) is effective only when the PTO clutch (32) is engaged.

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