JP2008196600A - Travel control device for work vehicle - Google Patents

Abstract

An object of the present invention is to operate a forward / reverse lever in a predetermined position (especially a high-speed position, and particularly, a sub-shift lever in a high-speed position) by operating the forward / reverse lever to the forward side, To provide a travel control device for a work vehicle in which the airframe does not reverse rapidly.
A shift lever 20 for setting an operation amount of a hydraulic cylinder 93 for turning a trunnion shaft, a forward / reverse lever 10 for determining that an HST 34 is set to a forward side or a reverse side, and a lever 10 from a forward side to a reverse side Is a travel control device for controlling the speed of change of the cylinder 93 to the target position to be lower than the operation speed operated from the neutral position to the reverse side or the forward side, and the lever 10 is moved from the forward side to the reverse side. When switching to, the speed of change of the hydraulic cylinder 93 to the target position is slower than the operating speed when operating from the neutral position to the reverse (or forward) side, so for example, the hydraulic cylinder 93 moves rapidly from the forward side to the reverse side. To prevent it.
[Selection] Figure 12

Description

  The present invention has a transmission having a hydrostatic continuously variable transmission (hereinafter sometimes referred to as HST) used in work vehicles such as tractors for agriculture, construction, and transportation, and a transmission including a meshing transmission. The present invention relates to a vehicle travel control device.

  A work vehicle such as a tractor including a transmission including a hydrostatic continuously variable transmission and a meshing transmission is described in, for example, Japanese Patent Application Laid-Open No. 2002-250437.

In the transmission comprising the HST of the work vehicle and the meshing transmission, the rotational direction of the trunnion shaft is determined by detecting the operation position of the forward / reverse lever, and the trunnion shaft is determined based on the operation amount of the shift lever. The HST is output by adjusting the operation amount of the hydraulic cylinder that rotates the cylinder.
JP 2002-250437 A

  In the transmission, the rotation angle of the HST trunnion shaft by the shift lever is adjusted by adjusting the operation amount of the hydraulic cylinder according to the command of the controller according to the detection value of the detection sensor for detecting the operation amount of the shift lever. It is rotating.

  However, if the forward / reverse lever is operated from the forward side to the backward side through the neutral position, there is a problem in that the aircraft moves backward after a sudden stop. That is, if the forward / reverse lever is operated to the forward side, the shift lever is moved to a predetermined position (especially the high speed position, and particularly the auxiliary transmission lever is at the high speed position), and the forward / reverse lever is operated all at once in the forward direction, the aircraft will suddenly May go backwards.

  The object of the present invention is to operate the forward / reverse lever at a predetermined position (especially at the high speed position and particularly at the high speed position) by operating the forward / reverse lever to the forward side and operating the forward / reverse lever at a stretch during the forward movement. Even so, it is to provide a travel control device for a work vehicle in which the airframe does not reverse rapidly.

The above-mentioned problem of the present invention is solved by the following means.
That is, according to the first aspect of the present invention, the hydrostatic continuously variable transmission (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92) and the hydrostatic continuously variable transmission. A transmission including a meshing transmission (38) for changing the output of the apparatus to a plurality of shift speeds and a trunnion for determining the rotation angle of the trunnion shaft (92) of the hydrostatic continuously variable transmission (34) A hydraulic cylinder for pivoting the shaft (93), a shift lever (20) for setting the operation amount of the hydraulic cylinder for pivoting the trunnion shaft (93), and a hydrostatic stepless to continuously move the vehicle forward or backward A forward / reverse lever (10) that determines whether the transmission (34) is set to the forward side or the reverse side, and a trunnion shaft when the forward / reverse lever (10) is switched from the forward side to the reverse side (92) Rotating hydraulic cylinder ( 3) a travel control device for a working vehicle having a controller (90) to slower than the operating speed to manipulate the rate of change of the target position to the reverse side or the forward side from the neutral position.

  The invention according to claim 2 is a hydrostatic continuously variable transmission (HST) (34) for adjusting the rotational angle of the trunnion shaft (92) and outputting the power of the engine (5) and the hydrostatic continuously variable. The rotation angle of the trunnion shaft (92) of the transmission including the meshing transmission (38) that outputs the transmission by changing the output of the transmission to a plurality of shift stages and the hydrostatic continuously variable transmission (34) is determined. A hydraulic cylinder (93) for turning the trunnion shaft, a shift lever (20) for setting the operation amount of the hydraulic cylinder (93) for turning the trunnion shaft, and a non-hydrostatic type for moving the vehicle forward or backward A forward / reverse lever (10) for determining whether to set the step transmission (34) to the forward side or the reverse side, and a hydrostatic continuously variable transmission (34) by operating the forward / reverse lever (10) Forward side and forward side for each setting When the fixing means (10a), the reverse drive side setting means (10b), and the forward drive side setting means (10a) and the reverse drive side setting means (10b) of the forward / reverse lever (10) are abnormal, a predetermined operation of the transmission lever (20) is performed. A travel control device for a work vehicle, comprising a controller (90) that changes a range from a forward side to a reverse side so as to be shiftable.

  According to the first aspect of the invention, when the forward / reverse lever (10) is switched from the forward side to the reverse side, the speed of change of the trunnion hydraulic cylinder (93) to the target position is reverse (or forward) from the neutral position. Therefore, even if the forward / reverse lever (10) is suddenly operated, for example, it is possible to prevent sudden movement from the forward side to the reverse side at a high speed.

  According to the second aspect of the present invention, when the forward side setting means (10a) and the reverse side setting means (10b) of the forward / reverse lever (10) are abnormal, the predetermined operating range of the speed change lever (20) is reversed from the forward side. By changing so that the speed can be changed to the side, it is possible to move forward and backward only with the speed change lever (20).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In this 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.
Hereinafter, a tractor will be described as an example of a work vehicle. 1 is an overall side view, FIG. 2 is a plan view of the tractor of FIG. 1, FIG. 3 is a power diagram of the transmission of the tractor of FIG. 1, and FIG. 4 is a control block diagram of the transmission.

  The tractor shown in FIGS. 1 to 3 includes front wheels 2 and 2 and rear wheels 3 and 3 in the front and rear portions of the airframe, and appropriately reduces the rotational power of the engine 5 mounted on the front portion of the airframe by a transmission in the transmission case. Thus, the front wheels 2 and 2 and the rear wheels 3 and 3 are communicated.

  A steering handle 7 is supported on the handle post 6 in the center of the aircraft, 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 moved forward, the aircraft moves forward, and when it is moved backward, it moves backward. An accelerator lever 11 is provided on the opposite side of the forward / reverse lever 10 with the handle post 6 interposed therebetween, and an accelerator pedal 15 and left and right brake pedals 16 and 17 are disposed at the right corner of the step floor 13 to provide a step floor. A clutch pedal 19 is disposed at the left corner portion of 13.

  A shift lever 20 capable of selecting a gear position from 1st speed to 8th speed is located in the left front portion of the cockpit 9. A sub shift lever 21 capable of selecting any one of a low speed position, a medium speed position, a high speed position, and a neutral position is provided thereafter. Further, a PTO speed change lever 23 capable of selecting the 1st to 3rd speeds and the neutral position is provided on the rear side. Further, on the right side of the cockpit 9, a position lever 24 for setting the height of a working machine (not shown), an automatic tilling depth lever 25 for automatically setting the tilling depth of the field, and behind these levers 24, 25. Is provided with a right-up switch 27 and a right-down switch 28, followed by an automatic horizontal switch 29 (on to keep the tractor's absolute horizontal position horizontal with respect to the horizontal plane of the earth, not horizontal with respect to the field scene). ) And a backup switch 30 (when the forward / reverse lever 10 is in the reverse position, the work machine raising link 31 raises the work machine), and a work machine (not shown) is located behind the machine body. ) Are provided.

  FIG. 3 is a diagram showing a traveling transmission system of a tractor having the hydrostatic continuously variable transmission 34 of the present embodiment. The rotational power of the engine 5 is transmitted to the main clutch 32 that is operated by depressing the pedal-operated clutch pedal 19 and then transmitted from the HST input shaft 33 to the HST 34. The HST 34 includes a hydraulic closed circuit 34c including a variable displacement hydraulic pump 34a and a constant displacement hydraulic motor 34b. The hydraulic pump 34a is operated by power introduced from the HST input shaft 33, and the hydraulic pump 34a is operated. The hydraulic oil 34b is supplied to the hydraulic motor 34b from the hydraulic closed circuit 34c, and the traveling output shaft 36 is driven by the hydraulic motor 34b to supply power to the meshing transmission 38. Communicate.

  The sub-transmission clutch 39 of the meshing transmission 38 is slidable in the left and right directions in FIG. 39 is transmitted from the auxiliary transmission clutch 39 to the gear 45 of the transmission shaft 43, and the rotation of the transmission shaft 43 is driven through the differential device 46 at the traveling speed of the auxiliary transmission high speed stage.

  Further, when the auxiliary transmission clutch 39 is moved to the right from the position shown in FIG. 3 and the auxiliary transmission clutch 39 is engaged with the gear 45 and the medium speed gear 47 of the transmission shaft 43, the power from the travel output shaft 36 is transmitted to the gear. 41 is transmitted from the gear 49 to the subtransmission clutch 39 through the gear 50, the gear 51, and the gear 47 sequentially, and further transmitted from the subtransmission clutch 39 to the gear 45 of the transmission shaft 43. The movement of the rear wheel 3 is driven at the traveling speed of the intermediate speed stage through the differential device 46.

  When the auxiliary transmission clutch 39 further moves to the right side and engages with the gear 45 and the low speed gear 55 of the transmission shaft 43, the power from the travel output shaft 36 is transferred from the gear 49 to the gear 56 via the gear 41, and further from the gear 56. Is transmitted to the gear 57, transmitted from the gear 55 coaxial with the gear 57 to the auxiliary transmission clutch 39, and further transmitted from the auxiliary transmission clutch 39 to the gear 45 of the transmission shaft 43, and the rotation of the transmission shaft 43 is transmitted via the differential device 46. The rear wheel 3 is driven at the traveling speed of the sub-speed stage.

  Even if the sliding position of the auxiliary transmission clutch 39 is on the left or right side, the output from the transmission shaft 43 is transmitted to the front wheel output shaft 61 via the gears 53, 59, 60, etc. in order. At this time, if the hydraulic clutch 63 is connected, the front wheel 2 is driven together with the rear wheel 3 via the differential device 65, and if the hydraulic clutch 64 is connected, the front wheel speed is increased. It becomes. The hydraulic clutch 63 and the hydraulic clutch 64 are not connected together, and if the hydraulic clutch 63 and the hydraulic clutch 64 are not connected together, two-wheel drive is performed in which only the rear wheel 3 is driven.

  On the other hand, the power input from the HST input shaft 33 to the variable displacement hydraulic pump 34a is transmitted from the pump output shaft 66 to the drive system for PTO. The PTO drive system includes a PTO forward / reverse clutch 67 and a PTO auxiliary transmission clutch 68. When the tractor travels on the road, either one or both of the clutches 67 and 68 are in an unconnected state to drive the work machine. The PTO drive system is not driven.

  When working with the work implement in the field, the HST is set because the engine speed is set to the rated speed or a constant speed from the rated speed to the maximum speed by pulling the accelerator lever 11 toward the operator (front side). The input shaft 33 and the pump output shaft 66 rotate at a constant speed. The state shown in FIG. 3 is a neutral state, and the PTO shaft 69 directly connected to the pump output shaft 66 rotates together.

  When the PTO forward / reverse clutch 67 is slid in the left direction in the figure, the PTO forward / reverse clutch 67 meshes with the gear 70 and the gear 71 of the PTO shaft 69, so that the power of the PTO shaft 69 is the gear 70, the PTO forward / reverse clutch 67, and the gear 71. , The PTO transmission shaft 75 is driven through the gear 71a, the gear 72, the gear 74, the gear 78, the gear 77, and the gear 76 sequentially (PTO reverse rotation). When the PTO forward / reverse clutch 67 is slid in the right direction in the figure, the power of the PTO shaft 69 drives the PTO transmission shaft 75 through the gear 70, the PTO forward / reverse clutch 67, the gear 73, the gear 77, and the gear 76 sequentially. (PTO normal rotation).

  The power from the gear 78 interlocking with the driving of the gear 74 integrated with the gear 72 is also transmitted to the PTO transmission shaft 75, and when the PTO auxiliary transmission clutch 68 is in the position moved to the left most from the illustrated position, the gear 79 and the gear The gear dock 81 is engaged with the gear dock 83 provided in the PTO auxiliary transmission clutch 68 via 80, and the PTO first speed is obtained by the PTO drive shaft 84. When the PTO auxiliary transmission clutch 68 moves left or right from the illustrated position, power is transmitted to the PTO auxiliary transmission low speed gear 85 or the PTO auxiliary transmission high speed gear 86 that meshes in each case, and the gear 85, gear 68a. When the power is sequentially transmitted to the PTO drive shaft 84, the PTO second speed is obtained, and when the power is sequentially transmitted to the gear 86, the gear 68b and the PTO drive shaft 84, the PTO third speed is obtained.

  The tractor having the above-described configuration depresses the clutch pedal 19 when traveling on the road, and sets the auxiliary transmission lever 21 to a position suitable for traveling on the road (basically, the high-speed position may be set to the medium-speed position or the low-speed position). Next, the shift lever 20 is moved to an arbitrary position. The speed change lever 20 can be selected from a minimum speed of 1st speed to a maximum speed of 8th speed, but the basic speed when traveling on the road is 8th speed.

  Next, the forward / reverse lever 10 is moved forward or backward, and the engine pedal is increased by stepping on the accelerator pedal 15 while slowly releasing the clutch pedal 19 (with the main clutch 32 connected). At this time, even if the accelerator pedal 15 is fully depressed, the maximum speed is restricted to the position of the maximum speed stage (eight speed) of the speed change lever 20.

  Further, when working in the field, after depressing the clutch pedal 19, the sub-shift lever 21 is set to an appropriate position (basic is a low speed or medium speed position). Next, the shift lever 20 is moved to an arbitrary position (selectable from the first speed to the eighth speed according to the type of work), and the forward / reverse lever 10 is moved to the forward position. The accelerator lever 11 is moved to the pilot side (front side), and the engine speed is set to a rated speed or a maximum speed greater than the rated speed. Next, the clutch pedal 19 is moved forward (with the main clutch 32 connected). At this time, the engine speed is set between the rated speed and the maximum speed equal to or higher than the rated speed, but the working speed is regulated by the position of the transmission lever 20.

  Note that the accelerator pedal 11 is used instead of the accelerator pedal 15 during work using the work implement in the field. Further, when traveling on the road, the accelerator pedal 15 is used and the accelerator lever 11 is not used. When driving on the road, the accelerator pedal 15 can be operated in the same way as when driving a car, and the engine rotation must be kept constant when working in the field. . Therefore, the accelerator lever 11 is operated during the work, and even if the hand is released from the accelerator lever 11 during the work, it does not return to the original position. Therefore, it is possible to maintain a constant engine speed by maintaining the operated accelerator position.

  FIG. 5 shows a left side view of only the handle post 6, the airframe in the vicinity of the cockpit, and the speed change lever 20. FIG. 6 shows an enlarged view of the vicinity of the base of the speed change lever 20. The speed change lever 20 can change the speed stage from 1st to 8th speed, and a position sensor 20 a capable of detecting a position position corresponding to each speed stage is provided at the base of the lever 20. The detection value of the position sensor 20a is output to the controller 90 (FIG. 4).

  7 and 8 show a plan view of the transmission case 91 (FIGS. 7A and 8A) and a plan view of the HST 34 housed in the transmission case 91 (FIG. 7B). FIG. 8 (b)) is shown. FIG. 9 is a side view of the transmission case 91 as viewed from the direction of arrow A in FIG. As shown in FIGS. 5 to 9, a link mechanism 95 that connects the hydraulic cylinder 93 that rotates the trunnion shaft 92 of the HST 34 and the trunnion shaft 92 that protrudes outside the transmission case 91 is connected to the outer wall portion of the transmission case 91. It is attached to.

  The other end of the arm 95a having one end rotatably connected to the tip of the piston rod 93a of the cylinder 93 is rotatably supported on the outer wall of the transmission case 91, and the other end of the arm 95a is supported on the other end. One end of a rod 95b provided in a direction orthogonal to the longitudinal direction of the arm 95a is rotatably provided, and the other end of the rod 95b is substantially parallel to the arm 95a via a rotatable short arm 95c. The end of the rod 95d, whose length can be adjusted in the direction, is pivotally connected. The other end of the rod 95d whose length can be adjusted is rotatably connected to one end of a short arm 95e, and a boss 95f is fixed to the other end of the short arm 95e.

  The boss 95f is fixed to the shaft 95q with a bolt 95p. The shaft 95q is rotatably supported with respect to the transmission case 91, and a plate 95g is fixed to one end of the shaft 95q. The other end of the plate 95g is rotatably connected to a link arm 95h via a pin 95r, and the link arm 95h is rotatably connected to a cam 95j integrated with the trunnion shaft 92. Here, the cam 95j is fixed to the boss 95s, and the boss 95s is fixed to the trunnion shaft 92 by a bolt 95t.

  The plate 95g and the link arm 95h are connected by a pin 95r, and the connecting portion by the pin 95r has an arc-shaped elongated hole 95k1 of a fan-like member 95k fixed to the transmission case 91 with a shaft 95q as a pivot. Since the pin 95r is slidable only in the long hole 95k1, the rotation range of the cam 95j is also restricted within the range interlocked with the sliding of the pin 95r.

  By the link mechanism 95, the operation of the hydraulic cylinder 93 is interlocked with the arm 95a, the rod 95d, etc., and the cam 95j rotates together with the trunnion shaft 92. Further, the cam 95j is rotated by the cylinder 93 while the side surface of the cam 95j is in contact with the side surface of the roller 95m supported by the transmission case 91.

  A position sensor 92a (FIG. 7) that detects the rotation position of the trunnion shaft 92 by the operation of the trunnion hydraulic cylinder 93 is configured to detect the degree of rotation of the rotation shaft 93d. The position sensor 92a is connected to the other end of an arm 93c having one end rotatably provided on the opposite side of the rod 95d from the connecting portion of the arm 95e. Thereby, the position sensor 92a detects the movement (position) of the trunnion shaft 92. The position sensor 92a of the trunnion shaft 92 is set to a stopper 93e provided at the maximum extension position on the forward side of the piston rod 93a of the hydraulic cylinder 93 for turning the trunnion shaft and a stopper 93f (FIG. 9) provided at the minimum shortened position on the reverse side. Each position is set as a reference value that allows the trunnion shaft 92 to turn. The position where the roller 95m fits into the recess 95j1 of the cam 95j is the neutral position of the trunnion shaft 92, which is also a reference value. Each set position detected by the position sensor 92a is stored in the memory (EEPROM) of the controller 90 as a reference position. In this way, variations in the amount of operation of the link mechanism 95 by the hydraulic cylinder 93 that operates according to a command from the controller 90 is absorbed with each set position detected by the position sensor 92a as a reference position.

  7 shows a state where the trunnion shaft 92 is arranged with the swash plate 34d of the hydraulic pump 34a of the HST 34 facing the vehicle forward side, and is a plan view of the transmission case 91 of FIG. 8 (FIG. 8 (a)). ) And a plan view of the HST 34 housed in the transmission case 91 (FIG. 8B) shows a state in which the swash plate 34d of the hydraulic pump 34a of the HST 34 faces the neutral position. The neutral position of the trunnion shaft 92 is the position where the roller 95m fits into the concave portion 95j1 of 95j. The roller 95m is pushed by a spring from the direction of the arrow x in FIG. 10 is a plan view (FIG. 10A) of the transmission case 91 and a plan view of the HST 34 housed in the transmission case 91 (FIG. 10B) is a state where the hydraulic pump 34a of the HST 34 is shown. This shows a state in which the swash plate 34d is disposed toward the reverse side.

  FIG. 11 is a diagram showing the arrangement of shift switches 10a and 10b provided at the base of the forward / reverse lever 10 and the operation mode thereof. 11 (a) and 11 (c) are layout diagrams in which the forward shift switch 10a and the reverse shift switch 10b provided at the base of the forward / reverse lever 10 operate when the forward / reverse lever 10 is in the forward position and the reverse position. FIG. 11B shows a layout when the forward / reverse lever 10 is in the neutral position and does not come into contact with either the forward shift switch 10a or the reverse shift switch 10b.

  When the forward / reverse lever 10 is tilted forward from the neutral position so that the forward shift switch 10a of the forward / reverse lever 10 is operated, it is ready to move in the forward direction, and the reverse shift switch 10b of the forward / reverse lever 10 is operated. When the forward / reverse lever 10 is tilted backward from the neutral position, it is ready to move in the reverse direction. It should be noted that acceleration in the forward and backward directions of the vehicle is only performed by the shift lever 20.

  As shown in the flowchart of FIG. 12, when the controller 90 switches the forward / reverse lever 10 from the forward side to the reverse side, the controller 90 sets the movement change speed (X) to the target position of the trunnion hydraulic cylinder 93 in the forward / backward direction. It is set to a lower speed (X <Y) than the operation change speed (Y) when the lever 10 is operated backward or forward.

  For example, even if the forward / reverse lever 10 is moved to the reverse side via the neutral position while traveling at the eighth forward speed, the controller 90 ignores the neutral position, suddenly becomes the eighth reverse speed, and may move backward at a high speed. Therefore, the speed change shock at the time of forward / reverse switching of the forward / reverse lever 10 is reduced by changing the speed of the forward / reverse lever 10 in the neutral position at a speed lower than the operation change speed when operated to the reverse side or the forward side.

  Further, when the forward / reverse lever shift switches 10a and 10b are abnormal (for example, both the forward shift switch 10a and the reverse shift switch 10b are turned on), the rotation angle sensor 92a of the trunnion shaft 92 is controlled by the controller 90 by the shift lever 20. It is possible to specify from the forward end to the reverse end. For example, 8th to 5th speeds are set to the forward side, 4th speed is set to the neutral position, and 3rd to 1st speeds are set to the reverse side. Even if the shift switches 10a and 10b break down or the wiring is short-circuited, only the shift lever 20 is used. It is possible to move forward and backward.

  The procedure for allowing the shift lever 20 to move forward and backward is that the trunnion hydraulic cylinder 93 is once returned to the neutral position after the abnormality of the shift switches 10a and 10b, and the rotation angle sensor 92a of the trunnion shaft 92 at this time is neutral. When the transmission lever 20 detects the indicated position, the position may be set to the neutral position, and the trunnion hydraulic cylinder 93 may be output to the forward side or the reverse side according to the subsequent operation of the transmission lever 20.

  In this way, it is possible to avoid problems such as sudden reverse travel during forward travel or changes in travel speed depending on the position of the shift lever 20 when the shift switch 10a, 10b is abnormal, and forward / backward shift switch It is possible to travel even when there is an abnormality in 10a and 10b.

  In addition, when the shift lever position sensor 20a is abnormal, the set target value of the trunnion shaft 92 is set to the lowest speed (first speed) to ensure slow running to ensure stability when the sensor 20a is abnormal.

  Further, when the trunnion hydraulic cylinder position sensor 92a is abnormal, it is in a state in which the rotation angle of the trunnion shaft 92 cannot be detected. Therefore, the output of the trunnion hydraulic cylinder 93 is prohibited and the buzzer is continuously blown. To do.

  In this state, when the forward / reverse lever 10 is operated with the main clutch 32 disengaged, the trunnion hydraulic cylinder 93 is operated for a specified time in the operated direction (forward or reverse) to change the speed. The vehicle may be allowed to travel at the rotation position of the trunnion shaft 92 corresponding to the operation position of the lever 20.

  Since the engine power is not input to the transmission when the main clutch 32 is disengaged in this manner, the trunnion hydraulic cylinder 93 can be operated only at this time, thereby avoiding a dangerous state and simultaneously the trunnion hydraulic pressure. Even when the cylinder position sensor 92a breaks down, the vehicle can travel either forward or backward when the main clutch 32 is next engaged, and can move even if an abnormality occurs in a field or the like.

  Further, it may be configured such that the next time the main clutch 32 is engaged, the vehicle can run only when the sub-speed is in the low speed position. This is because if the trunnion hydraulic cylinder 93 is operated with the main clutch 32 disengaged to allow the trunnion shaft 92 to travel at the rotational position corresponding to the operating position of the speed change lever 20, the rotation of the trunnion shaft 92 can be achieved. Such a problem can be avoided because the moving position may be at the highest speed position, and there is a possibility of relatively high speed running even when the auxiliary gear position is at the high speed position.

  As shown in the flowchart of FIG. 13, when the clutch pedal 19 is depressed, the rotation angle of the trunnion shaft 92 is not in the neutral range regardless of the position of the transmission lever 20 and the forward / reverse lever 10. The hydraulic cylinder 93 may be adjusted so as to enter the neutral range.

Conventionally, the HST 34, the shift lever 20, and the forward / reverse lever 10 are connected by a mechanical link structure. However, the neutral region of the HST 34 is excessive in order to ensure safety. Therefore, when the clutch pedal 19 is stepped on, the traveling system is shut off by a mechanical link structure, but the operation of the HST 34 is not stopped (the swash plate of the HST is not neutral, so it is turning. )), Wasteful power is consumed, and the durability of the HST 34 is deteriorated.
Therefore, it is possible to ensure safety as a pre-stage when the engine 5 is started by avoiding the coupling mechanism having a mechanical link configuration and electrically operating the hydraulic cylinder 93 according to the above-described flow.

  Also, as shown in the flowchart of FIG. 14, when the clutch pedal 19 is depressed and then released, the shock when the main clutch 32 is engaged is alleviated at regular intervals (for example, 0.3 seconds) or By adopting a configuration that adjusts the rotational angle position of the trunnion shaft 92 to the corresponding shift position of the shift lever 20 so that it gradually returns from insensitivity to sensitivity in stages, it is possible to ensure safety as the first stage at the time of engine start. It becomes.

  Further, as shown in the flowchart of FIG. 15, when the vehicle speed is increased by adjusting the rotation angle of the trunnion shaft 92, the tilling depth control is sensitive for a certain period of time (for example, 0.5 seconds until the shift speed follows). (The working machine is moved up and down by hydraulic pulse control that shortens the pulse interval). In addition, when decelerating by adjusting the rotation angle of the trunnion shaft 92, the plowing control is insensitive (for example, the work machine is lifted up and down by increasing the pulse interval) for a certain time (for example, 0.5 seconds until the shift speed follows). Use hydraulic pulse control).

  Note that the tilling depth is set with the tilling depth adjustment dial 44 and the tilling depth sensitivity switch 40 is used to set the tilling depth sensitivity. However, when the vehicle is accelerated or decelerated by adjusting the rotation angle of the trunnion shaft 92 in the flowchart of FIG. Sensitive or insensitive to the sensitivity set by the sensitivity switch 40.

  In the above control, when the speed is increased, a load is applied to the work machine, so it is desirable to follow up quickly. This is because when the speed is increased, the front of the machine is raised, so that the working machine tends to descend and the plowing depth becomes too large and the load is excessively applied. In addition, since insensitivity is sufficient when decelerating, it is better to level the ground by moving the work implement slowly to the eyes because the engine brake is applied. At this time, the plowing depth is automatically controlled so as to be a value set by the plowing depth adjustment dial 44 so that the plowing depth is within a predetermined range. The depth sensor 58 (FIG. 4) detects and controls the depth set by the tilling depth adjustment dial 44, and the stroke sensor 48 (FIG. 4) detects the stroke of the trunnion hydraulic cylinder 93 to increase the speed. Or decelerate.

Further, as shown in the flowchart of FIG. 16, when the vehicle is accelerated and decelerated by adjusting the rotation angle of the trunnion shaft 92, the working machine does not operate for a certain period of time (for example, 0.5 seconds until the shift speed follows). You may comprise so that level control may become insensitive.
When the vehicle accelerates and decelerates, the traveling speed of the working machine that travels with the vehicle also fluctuates. Therefore, the fluctuation range of the detection value of the slope sensor 37 (FIG. 4) in which the shaking of the airframe itself detects the degree of inclination of the left and right of the airframe. The above-mentioned horizontal control is made insensitive because there is a possibility that the working machine malfunctions or an extra adjustment output and the leveling of the field becomes worse.

As shown in the flowchart of FIG. 17, the sensor check adjustment mode is set by turning on / off a specific switch or connecting a checker.
First, when the forward / reverse lever 10 is moved forward, the trunnion hydraulic cylinder 93 automatically moves at a predetermined speed to advance the aircraft. In this case, the shift lever 20 does not move, but the controller 90 automatically moves the trunnion hydraulic cylinder 93. At this time, the auxiliary transmission lever 21 is set to a low speed so as not to run at a high speed. When a predetermined switch (both horizontal changeover switch and horizontal sensitivity switch) is pressed when the aircraft starts moving forward, a trunnion shaft obtained by subtracting a predetermined angle (α) from the turning angle of the trunnion shaft 92 at the time of pressing. The rotation angle of 92 is stored as a neutral reference position.

  Therefore, if the aircraft is moving forward at a relatively high speed, the neutral position is shifted to the forward side. Therefore, it is necessary to advance the aircraft slowly to prevent this. However, when the neutral reference position is shifted to the forward side (to suppress high speed), it is effective to set the neutral reference value of the trunnion shaft 92 to a lower rotation angle.

  Further, after the neutral reference position is set, the aircraft is further advanced, and when the value of the position sensor 92a for detecting the rotation angle of the trunnion shaft 92 does not change, a predetermined value is determined from the detected rotation angle value. The rotation angle of the trunnion shaft 92 minus the angle (β) is stored as the maximum reference position on the forward side, and a buzzer is sounded to notify the operator that the reference value has been set.

  Next, when the forward / backward lever 10 is set to the reverse side and the machine body is moved backward, and the rotation angle of the trunnion shaft 92 does not change, the trunnion shaft obtained by subtracting a predetermined angle (γ) from the rotation angle detection value that has stopped changing. The rotation angle of 92 is stored as the reverse maximum reference position, and a buzzer is sounded to notify the operator that the reference value has been set.

  The predetermined angle α is for making the neutral dead zone as narrow as possible, and the predetermined angles β and γ are for preventing contact with the stoppers 93e and 93f, respectively. However, the stoppers 93e and 93f are necessary for preventing overrun. Further, the maximum reference position on the forward / rearward side of the rotation angle of the trunnion shaft 92 is provided with stoppers 93e and 93f at the maximum forward side and the maximum reverse side of the operating range of the trunnion hydraulic cylinder 93, respectively. In the adjustment mode, the control reference value of the rotation angle of the trunnion shaft 92 can be detected almost automatically, and the control of the rotation angle of the trunnion shaft 92 can be realized.

  Based on the neutral reference position, the forward maximum reference position, and the reverse maximum reference position stored as described above, the shift lever 20 is operated to control the rotation angle of the trunnion shaft 92 to move the aircraft forward and backward.

  As described above, since the conventional transmission is connected to the HST, the shift lever, and the forward / reverse lever with a mechanical link configuration, the HST neutral range is excessive for ensuring safety. There was room for.

  Therefore, the above-described configuration of the present embodiment reduces the number of airframe links as much as possible and electrically interlocks the HST 34, the shift lever 20, and the forward / reverse lever 10 to ensure safety as the first stage when starting the engine. Become. In addition, when the work machine is raised, the load is reduced and the vehicle speed is increased. In this case, by decelerating with the above-described configuration, there is an energy saving effect. However, when the work machine is lowered to the farm scene, the load is restored, so that the vehicle speed is restored to the original state as described above.

  As shown in the flowchart of FIG. 18, when the amount of depression of the accelerator pedal 15 for engine speed control is small, the hysteresis (dead zone) is increased to almost ignore the variation of the amount of depression, and the amount of depression of the accelerator pedal 15 is large. In some cases, the hysteresis may be reduced so that the change in the stepping amount is sensitively reflected so that it can be precisely controlled.

  This is because when the amount of depression of the accelerator pedal 15 is small, the throttle valve of the engine 5 is hardly pulled, and the operation of the accelerator pedal 15 is hardly loaded. At that time, although the accelerator pedal 15 is depressed by a certain amount, the depression amount of the accelerator pedal 15 slightly changes due to vibrations of the airframe, etc., thereby driving the HST trunnion shaft 92, resulting in fluctuations in vehicle speed during traveling, It is uncomfortable for the operator. With the above configuration, the anxiety can be resolved and vehicle speed fluctuations can be reduced during traveling.

  As shown in the flowchart of FIG. 19, instead of the depression amount of the accelerator pedal 15, the engine speed is detected by the engine speed sensor 35. When the engine speed is low, the hysteresis is increased, and when the engine speed is high, the hysteresis is increased. It is good also as a structure made small.

Further, the time until the forward / reverse lever 10 enters the forward position to the reverse position is detected, and the drive of the HST trunnion shaft 92 is made faster or slower according to the time. Thus, when the forward / reverse lever 10 is switched from the forward side to the reverse side at once, the on-time for turning output of the trunnion shaft 92 is increased, so that the forward, stop, reverse movement can be made smooth. The time from when the forward / reverse lever 10 is in the reverse position to when the lever 10 is switched to the forward position is also the same.
However, if this control is performed during high-speed travel, there is a risk of suddenly switching from high-speed forward travel to high-speed reverse travel. Therefore, the above control is performed only during sub-speed travel at low speed.

  As shown in the flowchart of FIG. 20, if the time from when the forward / reverse lever 10 is in the forward position to when switching to the reverse position is detected and the time is within a certain time (for example, 2 seconds), The output on time to the HST trunnion shaft 92 may be doubled as usual to increase the driving speed of the trunnion shaft 92. This control is similarly performed for the time from when the forward / reverse lever 10 enters the reverse position to when the forward / reverse lever 10 switches to the forward position. Further, as described above, this control is limited to the time of sub-shifting low speed traveling.

  As shown in the flowchart of FIG. 21, after doubling the output on time to the trunnion shaft 92 shown in the flowchart of FIG. 20, when the trunnion shaft 92 reaches the target stop position, the output on time is set to the normal original value. If it is configured to return to the time, the movement from forward to stop can be made quick, and the movement from stop to reverse can be smoothly increased.

  The present invention can be used as a travel control device for work vehicles such as tractors for agriculture, construction, and transportation.

It is a left view of the tractor of one Example of this invention. It is a top view of the tractor of FIG. It is a power diagram of the transmission of the tractor of FIG. It is a control block diagram of the transmission of the tractor of FIG. FIG. 2 is a left side view of only the handle post, the vehicle body near the cockpit, and the speed change lever of the tractor of FIG. 1. An enlarged view of the vicinity of the base portion of the transmission lever 20 of the tractor of FIG. 1 is shown. FIG. 8 is a plan view (FIG. 7A) of the transmission case when the tractor of FIG. 1 moves forward, and a plan view of the HST housed in the transmission case (FIG. 7B). FIG. 8 is a plan view (FIG. 8A) of the transmission case when the tractor of FIG. 1 is neutral and a plan view of the HST housed in the transmission case (FIG. 8B). It is the side view of the transmission case seen from the arrow A direction of Fig.8 (a). FIG. 10 is a plan view (FIG. 10A) of the transmission case when the tractor of FIG. 1 moves backward, and a plan view (FIG. 10B) of the HST accommodated in the transmission case. 1 provided at the base of the forward / reverse lever when the forward / backward lever of the tractor is in the forward position (FIG. 11 (a)), the neutral position (FIG. 11 (b)) and the reverse position (FIG. 11 (c)). It is a figure which shows arrangement | positioning of a shift switch, and its operation | movement aspect. 2 is a flowchart for controlling the operation speed of a hydraulic cylinder for operating a trunnion shaft at the time of forward / reverse switching of a forward / reverse lever of the tractor of FIG. 1. 2 is a flowchart for control to return a trunnion shaft to a neutral position when a clutch pedal of the tractor in FIG. 1 is depressed. FIG. 2 is a control flowchart for slowing down the rotation speed of a trunnion shaft when the clutch pedal of the tractor in FIG. 1 is depressed and released. 2 is a flowchart for control that makes the tilling depth control sensitive at the time of speed increase due to rotation of the trunnion shaft of the tractor of FIG. 1 and makes the tilling depth control insensitive at the time of deceleration. FIG. 2 is a control flowchart for desensitizing the horizontal control during acceleration or deceleration due to rotation of the trunnion shaft of the tractor of FIG. 1. 2 is a flowchart for controlling a rotation angle of a trunnion shaft based on a neutral reference position of a forward / reverse lever, a forward maximum reference position, and a reverse maximum reference position when the tractor of FIG. 1 is started. 2 is a flowchart for control in which a dead zone of the depression amount of the clutch pedal is changed depending on the depression amount of the clutch pedal of the tractor of FIG. 2 is a flowchart for control for changing a dead zone of the engine speed according to the engine speed of the tractor of FIG. 1. When switching the forward / reverse lever of the tractor in FIG. 1 from the forward side to the reverse side, or when switching from the reverse side to the forward side, if the switching time is within a certain time, the operating speed of the trunnion shaft operating hydraulic cylinder is adjusted to the normal speed. It is a flowchart for control to double. When switching the forward / backward lever of the tractor in FIG. 1 from the forward side to the reverse side or when switching from the reverse side to the forward side, if the switching time is within a certain time, the operation speed of the trunnion shaft operating hydraulic cylinder is It is the flowchart for control which returns to a normal operation speed, if a trunnion axis | shaft will be in a neutral position after making it 2 times.

Explanation of symbols

2 Front wheel 3 Rear wheel 5 Engine 6 Handle post 7 Steering handle 9 Seat 10 Forward / reverse lever 10a Forward shift switch 10b Reverse shift switch 11 Accelerator lever 11a Throttle sensor 13 Step floor 15 Accelerator pedal 16, 17 Brake pedal 19 Clutch pedal 20 Shift lever 20a Position sensor 21 Sub shift lever 23 PTO shift lever 24 Position lever 25 Automatic tilling lever 27 Right up switch 28 Right down switch 29 Automatic horizontal switch 30 Backup switch 31 Work equipment raising link 32 Main clutch 33 HST input shaft 34 HST 34a Hydraulic pump 34b Hydraulic motor 34c Hydraulic closed circuit 34d Swash plate 35 Engine speed sensor 36 Travel output shaft 37 Slope sensor 38 Meshing type change Speed gear 39 Sub-shift clutch 40 Plowing depth sensitivity switch 41 Gear 42 High speed gear 43 Transmission shaft 44 Plowing depth adjustment dial 45 Gear 46 Differential gear 47 Medium speed gear 48 Stroke sensor 49, 50, 51, 53 Gear 55 Low speed gear 56 , 57, 59, 60 Gear 58 Depth sensor 61 Front wheel output shaft 63 Hydraulic clutch 64 Hydraulic clutch 65 Differential device 66 Pump output shaft 67 PTO forward / reverse clutch 68 PTO auxiliary transmission clutch 69 PTO shaft 70 to 74 Gear 75 PTO transmission shaft 76, 78 , 79, 80 Gear 81, 83 Gear dock 84 PTO drive shaft 85 PTO auxiliary transmission low speed gear 86 PTO auxiliary transmission high speed gear
90 controller 91 transmission case 92 trunnion shaft 92a position sensor 93 hydraulic cylinder 93a piston rod 93c arm 93d rotation shaft 93e, 93f stopper 95 link mechanism 95a arm 95b rod 95c arm 95d rod 95e short arm 95f boss 95g plate 95h link arm 95j Cam 95k Fan-shaped member 95k1 Slot 95m Roller 95p Bolt 95q Shaft 95r Pin 95s Boss 95t Bolt

Claims (2)

The hydrostatic continuously variable transmission (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92), and the output of the hydrostatic continuously variable transmission is changed to a plurality of shift stages. A transmission including a meshing transmission (38) for output
A hydraulic cylinder (93) for turning the trunnion shaft for determining the turning angle of the trunnion shaft (92) of the hydrostatic continuously variable transmission (34);
A speed change lever (20) for setting the operation amount of the hydraulic cylinder (93) for turning the trunnion shaft;
A forward / reverse lever (10) for determining whether to set the hydrostatic continuously variable transmission (34) to the forward side or the reverse side in order to operate the vehicle forward or backward;
When the forward / reverse lever (10) is switched from the forward side to the reverse side, the speed of change of the trunnion shaft (92) rotating hydraulic cylinder (93) to the target position is operated from the neutral position to the reverse side or forward side. A travel control device for a work vehicle, comprising: a controller (90) for lowering the operating speed than the operating speed. A hydrostatic continuously variable transmission (HST) (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92), and outputs of the hydrostatic continuously variable transmission are shifted to a plurality of speeds. A transmission including a meshing transmission (38) for changing to a stage and outputting;
A hydraulic cylinder (93) for turning the trunnion shaft for determining the turning angle of the trunnion shaft (92) of the hydrostatic continuously variable transmission (34);
A speed change lever (20) for setting the operation amount of the hydraulic cylinder (93) for turning the trunnion shaft;
A forward / reverse lever (10) for determining whether to set the hydrostatic continuously variable transmission (34) to the forward side or the reverse side in order to operate the vehicle forward or backward;
Forward-side setting means (10a) and reverse-side setting means (10b) for setting the forward side and the reverse side of the hydrostatic continuously variable transmission (34) by operating the forward / reverse lever (10),
A controller that changes a predetermined operating range of the speed change lever (20) from the forward side to the reverse side when the forward side setting means (10a) and the reverse side setting means (10b) of the forward / reverse lever (10) are abnormal. 90). A travel control device for a work vehicle.

Images