JP2008032194A - Continuously variable transmission controller of work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a stopping distance by suppressing a drive torque increasing function of a toroidal transmission mechanism when an abrupt stop is required while a work vehicle having the toroidal transmission mechanism travels on a road. <P>SOLUTION: A constitution is formed by assembling the toroidal transmission mechanism 4 into a power transmission part for driving travel wheels of the work vehicle. The constitution has a travel mode selector means for selectively setting a work travel mode or a road travel mode. An output of the toroidal transmission mechanism 4 is controlled to a decelerating side according to whether the travel mode selector means is set to the road travel mode or a forward/backward traveling selector means installed in the power transmission part is set to a backward traveling side and that a braking determination signal BS is inputted according to the state of the braking operation of the work vehicle or the state of the operation accompanied by braking. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a continuously variable transmission control device for a power transmission unit in a work vehicle such as a tractor or a front loader provided with a ground work machine.

Transmissions incorporating a toroidal transmission mechanism as a continuously variable transmission mechanism with good power transmission efficiency are used in work vehicles.
Japanese Patent No. 3444324 JP, 2005-273734, A A work vehicle provided with a continuously variable transmission using a toroidal transmission mechanism in a travel drive part has a work mode for performing ground work and a road travel mode for simple movement, and the running force during work. When the wheel is subjected to resistance in order to increase the speed, the gear ratio is automatically changed to increase the driving torque of the wheel to maintain traveling.

  As described above, as a characteristic of the toroidal transmission mechanism, when a load is applied to the drive wheel, the drive torque is increased. Therefore, when the vehicle is driven on the road with the brake, the brake is forcibly applied while the drive force is applied to the wheel. There is a tendency that the stopping distance tends to be long and the stopping distance tends to be long, and the stopping distance cannot be shortened even if sudden braking is performed to avoid danger.

  Therefore, an object of the present invention is to reduce the stopping distance by suppressing the function of increasing the driving torque of the toroidal transmission mechanism when a sudden stop is required when the vehicle is traveling on the road with a work vehicle using the toroidal transmission mechanism.

The above object of the present invention is achieved by the following configuration.
That is, the invention according to claim 1 is a travel that selects and sets the work travel mode or the road travel mode in a configuration in which the toroidal transmission mechanism 4 is incorporated in the power transmission unit that drives the traveling wheel drive of the work vehicle. There is provided a mode switching means, and the traveling mode switching means is set to the road traveling mode, or the forward / reverse switching means provided in the power transmission unit is set to the reverse traveling side, and braking of the work vehicle. The output of the toroidal transmission mechanism 4 is controlled to the deceleration side according to the condition for inputting the braking determination signal BS based on the operating state or the operating state involving braking.

  With the above configuration, when the work vehicle is used for ground work, the work wheel is set to the work mode and the brake wheel on one side is depressed to lock the drive wheel on the depression side and the other drive wheel is accelerated. Can make a quick turn. Road driving is set to the road driving mode, and reverse driving is determined by changing the shift to reverse. When the braking determination signal BS is input, the toroidal transmission mechanism 4 is controlled to the output deceleration side to rapidly decelerate the drive wheels. The brake is applied and the brake is applied.

According to a second aspect of the present invention, in the configuration of the first aspect, the braking determination signal BS is input when the deceleration due to braking of the work vehicle exceeds a predetermined value.
According to a third aspect of the present invention, in the configuration of the first aspect, the brake determination signal BS is input when the steering rotational speed exceeds a predetermined value.

  According to a fourth aspect of the present invention, in the configuration of the first aspect, the brake determination signal BS is input when the brake pedal depression speed or depression angle exceeds a predetermined value.

  According to a fifth aspect of the present invention, in the configuration of the first aspect, the brake determination signal BS is input when the engine speed or the speed reduction rate exceeds a predetermined value.

  According to the first aspect of the present invention, when the road traveling is set to the road traveling mode, the reverse traveling is determined by changing the speed to reverse, and when the braking determination signal BS is input, the toroidal transmission mechanism 4 is set to the output deceleration side. The driving distance is suddenly decelerated and braked, and the brake is further applied, so that the stopping distance becomes shorter than the braking by the brake in the driven state.

  According to the second aspect of the present invention, since the input of the braking determination signal BS is executed when the deceleration due to braking of the work vehicle exceeds a predetermined value, it is determined that the operation is a sudden braking stop operation during traveling on the road. And safety is improved by shortening the stop distance.

  According to the third aspect of the present invention, the braking determination signal BS is input when the rotational speed of the steering wheel exceeds a predetermined value. Safety is improved by shortening.

  According to the fourth aspect of the present invention, the brake determination signal BS is input when the brake pedal depressing speed or depressing angle exceeds a predetermined value. Safety is improved by shortening the distance.

  In the invention according to claim 5, since the input of the braking determination signal BS is executed when the engine speed or the speed reduction rate exceeds a predetermined value, for example, the engine speed is equal to or less than idling. If the number of revolutions is constant, the safety is improved by determining the sudden braking when traveling on the road and shortening the stop distance.

Hereinafter, an embodiment in which the present invention is implemented in an agricultural tractor will be described with reference to the drawings.
As shown in FIG. 1, the mission case 1 is constructed integrally by connecting three cases of a front case 1 a, a middle case 1 b, and a rear case 1 c from the front.
The front case 1a has a front partition wall 2 and a rear partition wall 3, and is connected to the variator shaft 10, the traveling drive input shaft 11, the PTO input shaft 12, and the front wheel drive shaft 13 from above in the front and rear partition walls 2, 3. The relay shaft 42 is pivotally supported. A main input shaft 14 directly connected to the output shaft of the engine E is mounted on the coaxial cable in front of the variator shaft 10.

  The gear 15 fixed to the main input shaft 14 on the inner side of the front bulkhead 2 meshes with the large diameter gear portion of the large and small gear 16 fixed to the lower travel drive input shaft 11 to increase speed transmission, and the small diameter gear of the large and small gear 16 The gear 18 fixed to the lower PTO input shaft 12 is meshed with the lower part, and is decelerated and transmitted. The PTO input shaft 12 is connected to the PTO shaft transmission mechanism 44 in the middle case 1b, but a one-way clutch 97 is provided in the middle case 1b on the front side of the PTO shaft transmission mechanism 44 to prevent reverse rotation due to engine back-up. ing.

A gear 75 is fixed in the middle of the front and rear partition walls 2 and 3 of the PTO input shaft 12, and this gear 75 is engaged with and driven by a gear 76 of an oil pump 77 provided at the bottom. The oil pump 77 is attached to the intermediate wall 98 in the front case 1a with bolts 99, and simultaneously with this attachment, the gear 76 is sandwiched and held rotatably. (See Figure 5)
The lowermost relay shaft 42 transmits power to the front differential shaft 17 via the front wheel drive shaft 13 on the front side by transmission from the middle case 1b described later. The front differential shaft 17 drives the left and right front wheels 20 via the front differential gear 19. (See Figure 2)
The toroidal speed change mechanism 4 mounted on the variator shaft 10 includes two output disks 4a and 4a that rotate integrally with the variator shaft 4, and a lower travel drive travel drive input shaft 11 that is positioned at the center of both output disks 4a and 4a. The input disks 4b and 4b that rotate together with the gear 23 that meshes with the fixed gear 21 via the relay gear 22, and the rotating roller that is supported at the tip of the cylinder piston between the output disks 4a and 4a and the input disks 4b and 4b. It is set as the structure (variator mechanism) which clamps two or more. The tilt angles of the plurality of rotating rollers and cylinder pistons (hereinafter referred to as “power rollers 24”) are changed by hydraulic operation to change the tilt angle of the rollers, and the output disks 4a, 4b, The power transmission ratio transmitted to 4a is changed, and the rotation of the variator shaft 10 is changed. This speed change transmission efficiency is good at about 80 to 90%, and is characterized by high transmission efficiency especially at a low speed.

  Oil seals 56, 57, 58, 59 for airtightly separating the front case 1a and the middle case 1b are mounted on the rear partition wall 3 that pivotally supports the variator shaft 10 to which the toroidal transmission mechanism 4 is mounted and the travel drive input shaft 11. However, an air hole 29 leading to the space between the oil seals 56, 57, 58, 59 is provided to the outside of the case so that the airtightness of the front case 1a and the middle case 1b is maintained by the blizzard function. . The air hole 29 is connected to the oil seals 68 and 69 of the PTO input shaft 12 and the shaft oil seals 70 and 71 of the front wheel speed increasing clutch 40 connected to the relay shaft 42.

  The rotation of the variator shaft 10 is planetary via a gear 26 spline-fitted to the input clutch shaft 25 connected to the variator shaft 10 on the middle case 1b side of the rear partition wall 3 and a one-way clutch 60 (hereinafter referred to as “sprag 60”). The planetary gear 79 of the planetary mechanism 61 is pivotally supported by the pin 81 on the gear support 80, and the sun gear 78 of the planetary mechanism 61 that is directly splined to the input clutch shaft 25 is also driven. The extension shaft 62 of the travel drive input shaft 11 is spline-fitted with a one-way clutch 27 (sprag 27) that meshes with the gear 26 and a gear 63 that meshes with the outer gear 28 of the sprag 60 to transmit power. The ring gear 100 is driven at a reduced speed by such a driving configuration of the planetary gear 79 and the sun gear 78 of the planetary mechanism 61. In addition, the outer gear 28 is formed in the sprag 60, and the transmission structure is simplified by direct transmission, so that the transmission from low rhedium to high rhedium, which will be described later, can be performed smoothly without any step.

  The ring gear 100 is fixed by being sandwiched between the front and rear cases 73 and 74, and the rotation of the ring gear 100 becomes the rotation of the transmission drum 67 of the low-speed side clutch 64 via the rear case 74. Through zero and then rotate to a low speed forward rotation (referred to as “low radium”).

  The planetary gear support 80 is supported by the bearing 83 on the inner support wall 82 provided in the middle case 1 b, and the front case is supported by the bearing 84 on the inner support wall 82. The inner support wall 82 is provided with an oil hole 85 communicating with an oil hole 86 provided in the planetary gear support 80, and another oil hole 87 provided in the planetary gear support 80 is provided in the pin 81 of the planetary gear 79. 88 is used to lubricate the shaft support bush of the planetary gear 79.

  The sun gear integrated transmission drum 101 of the high-speed clutch 65 is spline-fitted to the input clutch shaft 25 that is spline-fitted to the gear 26 at the end of the variator shaft 10, and the speed change due to the inclination of the power roller 24 is performed at this high speed. The transmission drum 101 of the side clutch 65 is shifted to a higher speed (referred to as “high rhedium”) by taking over the maximum forward rotation speed of the low speed side clutch 64.

  The high speed side clutch 65 and the low speed side clutch 64 are encased by the planetary gear set on the front side and the rear case 74, but the lubricating oil is accumulated in the rear case 74 even at a position floating above the lubricating oil on the upper side of the middle case 1b. To prevent running out of oil.

  With the above configuration, if the low-speed clutch 64 is connected, the output clutch shaft 66 is shifted from low-speed reverse rotation to zero-speed normal rotation through the low-speed reverse rotation. The inclination of the power roller 24 is changed. Intermittent timing of the low speed clutch 64 and the high speed clutch 65, so-called low rhedium to high rhedium transfer is controlled by the high / low clutch 30 intermittently, and smoothly shifts from low speed reverse rotation to zero speed high speed normal rotation. Become.

  The gear 31 that is spline-fitted to the rear end of the output clutch shaft 66 of the high / low clutch 30 is engaged with the gear 33 that is spline-fitted to the differential shaft 32 of the rear differential gear 34 to drive the differential shaft 32. The rotation of the differential shaft 32 is transmitted to the left and right rear wheels 35 via the rear differential gear 34.

  The rotation of the differential shaft 32 is transmitted from a gear 37 to a gear 38 that is spline-fitted to a front wheel drive extension shaft 39 via a dual gear 36 that is loosely fitted to the PTO output shaft 41 to drive the front wheel drive extension shaft 39.

  The front wheel drive extension shaft 39 is equipped with a so-called front wheel speed increasing clutch 40 that drives the front wheels at the same speed or increased speed when the tractor turns. Further, the front wheel drive extension shaft 39 is connected to the front wheel drive extension shaft 39 via the relay shaft 42. The shaft 13 is connected to be transmitted.

  With the above configuration, the rotation of the engine E is transmitted to the toroidal transmission mechanism 4, and the rotation that is changed by the toroidal transmission mechanism 4 is transmitted to the high / low clutch 30. When the low speed clutch of the high / low clutch 30 is connected and the inclination of the power roller 24 of the toroidal transmission mechanism 4 is changed, the output rotation is steplessly shifted from reverse to forward in the low speed range. This speed change is suitable for traveling conditions in which the work vehicle moves forward and backward at a low speed suitable for ground work. When the inclination of the power roller 24 of the toroidal transmission mechanism 4 is changed by increasing the speed of the high / low clutch 30, the output rotation is steplessly shifted from normal rotation to reverse rotation within the high speed range. This speed change is suitable for traveling conditions in which the work vehicle moves on the road.

The PTO output shaft 41 that drives the ground work machine is transmitted as follows.
Inside the front and rear partition walls 2 and 3, the gear 43 fixed to the traveling drive traveling drive input shaft 11 pivoted on the lower part of the toroidal transmission mechanism 4 is meshed with the gear 18 fixed to the PTO input shaft 12, and this PTO input The rotation of the shaft 12 is transmitted to the PTO output shaft 41 via a PTO shaft transmission mechanism 44 and a PTO clutch 45 provided at the rear portion of the rear partition 3. The rotation of the PTO output shaft 41 is transmitted to the PTO output shaft 41 after being shifted to an appropriate rotational speed by the PTO shaft second transmission mechanism 46 provided in the rear case 1c.

  In this way, the front and rear partition walls 2 and 3 incorporating the toroidal speed change mechanism 4 are supported by the travel drive travel drive input shaft 11, the PTO input shaft 12 and the front wheel drive shaft 13, so that there are few gear sets. Therefore, the hydraulic oil accumulated in the tank is hardly agitated, and foaming of the hydraulic oil is prevented as much as possible to reduce the adverse effect on the toroidal transmission mechanism 4.

  The output side end of the variator shaft 10 is spline-fitted to the gear 26 to transmit power, but the gear 26 is supported on the rear partition 3 by the bearing 54 and the oil seal 55 is used for operating the toroidal transmission mechanism hydraulic oil. The mission oil is not mixed.

Next, the traveling control state in this work vehicle will be described.
FIG. 7 is a control block diagram of control signals relating to the following travel control. The signals input to the controller 89 are as follows.

  Linear shift (F) 90 to forward switching signal, linear shift (R) 91 to reverse switching signal, traveling mode switching switch 92 to 2- / 4-wheel drive switching signal, work selection switch 93 to ground work switching signal such as tillage, speed change Travel speed from lever 94, accelerator pedal depression speed and depression angle from accelerator pedal sensor 95, left brake pedal sensor 96 and right brake pedal sensor 102 from each brake pedal depression speed and depression position, pressure sensor (S1) 103 And pressure sensor (S2) 104 to control pressure of power roller 24, pressure sensor (Low clutch) 105 and pressure sensor (High clutch) 106 to control pressure of high / low clutch 30, throttle sensor 107 to throttle opening, engine From the rotation sensor 108, the engine speed, The rotation speed of the input disk 4b from the eta input rotation sensor 109, the rotation speed of the output disk 4a from the variator output rotation sensor 110, the traveling speed of the work vehicle from the vehicle speed sensor 111, the hydraulic oil temperature in the transmission case 1 from the oil temperature sensor 112, The rotational speed of the PTO output shaft 41 from the PTO rotation sensor 113, the rotational speed and rotation angle of the steering from the steering sensor 114, the connection signal of the left and right brake pedals from the brake pedal connection sensor 121, the rotational torque applied to the drive axle from the axle torque sensor 123, This is the traction force applied from the traction force sensor 124 to the traction rod of the work implement.

  The signal output from the controller 89 is a control signal for the power roller 24 to the display device 115, a control signal for the power roller 24 to the roller SOL (S1) 116 and a roller SOL (S2) 117, and a low signal to the low clutch SOL118. For example, a control signal for the high / low clutch 30 to the clutch SOL119, a brake control 122 signal for the brake, and the like. Input / output of information and control signals with the work machine controller 120 is also performed.

FIG. 8 is a control flowchart of the toroidal transmission mechanism 4 when the brake pedal is depressed during traveling. During forward traveling in step S1, the mode change switch is traveling on the road in step S2, and the brake pedal is depressed in step S3. If the deceleration detected by the vehicle speed sensor in step S4 is constant (for example, 3 m / S ² ), the control solenoid (roller) of the power roller 24 in step S5 is determined to be a sudden braking stop operation during driving on the road. SOL (S1) and roller SOL (S2)) are controlled so as to reduce the speed ratio. If the deceleration is less than a certain value in step S4, the power roller 24 is controlled as usual, and the output torque is increased while stopping in step S7. In this embodiment, the mode changeover switch is set to the work mode when the travel mode changeover switch 92 enters the four-wheel drive side and the work selection switch 93 is in a selected state of the ground work. When the switch 92 enters the two-wheel drive side and the work selection switch 93 is in a non-working position where no work is selected, the road travel mode is set, but more simply, the travel mode changeover switch 92 is in the two-wheel drive state. May be determined as the road traveling mode, or may be determined as the road traveling mode when the work selection switch 93 is in the non-working position.

  FIG. 9 is a control flowchart of the toroidal transmission mechanism 4 when the brake pedal is depressed during traveling, as in FIG. 8. The difference from FIG. 8 is the control during reverse traveling, in which the deceleration is constant in reverse in step S10. In the case of the above sudden braking, as a danger avoidance, the gear ratio of the power roller 24 is controlled so as to be decelerated to enable sudden stop or sudden turn.

  FIG. 10 is a control flowchart of the toroidal transmission mechanism 4 when the brake pedal is depressed during forward travel, as in FIG. 8. The difference from FIG. 8 is that the speed at which the steering wheel is turned off in step S33 is constant in the sudden braking determination ( For example, if it is 90 ° / S) or more, it is controlled to reduce the gear ratio of the power roller 24 as a risk-avoidance sudden braking when traveling on the road, thereby enabling sudden turning and stopping.

FIG. 11 is a control in FIG. 10 that enables a turn while decelerating in a case where a danger avoidance turn is made only by steering without operating a brake.
FIG. 12 is a control in which the sudden braking determination is performed based on the depression angle of the brake pedal in the control of FIG. 8, and if the depression angle of the brake pedal is equal to or larger than a certain angle (for example, 40 °) in step S52, As a sudden braking at the time of traveling on the road of S53, the gear ratio of the power roller 24 is controlled to be reduced, and the sudden stop of step S55 is enabled.

  FIG. 13 is a control in which the sudden braking determination is performed at the depression speed of the brake pedal as in FIG. 12, and if the depression speed of the brake pedal is equal to or higher than a certain speed (for example, 90 ° / S) in step S62, As a sudden braking at the time of traveling on the road in step S63, the speed ratio of the power roller 24 is controlled to be reduced, and the sudden stop in step S65 is enabled.

  FIG. 14 is a control in which the sudden braking determination is performed based on the engine speed determination. If the engine speed is equal to or less than a certain engine speed at idling or less (eg, 800 rpm) in step S73, the vehicle travels on the road in step S74. As a sudden braking at the time, the speed ratio of the power roller 24 is controlled to be decelerated, and the sudden stop of step S76 is enabled.

  FIG. 15 is a control in which the sudden braking determination is performed based on the engine rotation speed reduction rate determination as in FIG. 14. If the engine speed is greater than a certain rotation speed reduction rate (eg, 2000 rpm / S) in step S83, FIG. As a sudden braking at the time of traveling on the road in step S84, the speed ratio of the power roller 24 is controlled to be reduced to enable the sudden stop in step S86.

FIG. 16 is a control in which the traveling on the road is determined by connecting the left and right brake pedals in the control of FIG. 9, and the traveling is stopped without turning in step S96.
FIG. 17 shows that when driving with high rhedium, braking automatically switches from high rhedium to low rhedium, that is, a high speed clutch to a low speed clutch. It is control to judge.

  During forward traveling at step S100, when the mode changeover switch is traveling on the road at step S101 and braking is performed at step S103 while traveling at high rhedium at step S102, switching from high rhedium to low rhedium at step S104, the switching speed at step S105. If it is earlier than a predetermined value, control is performed to reduce the speed ratio of the power roller 24 in step S106, and the process is stopped in step S108. If the switching speed is slower than the predetermined speed in step S105, the control of the power roller 24 is stopped in step S108 while the output torque is increased as usual.

FIG. 18 is a point in which road driving is determined in step S111 in the sudden braking determination based on the switching speed from high rhedium to low rhedium as in the control of FIG.
FIG. 19 is a control for determining sudden braking by sensing that the accelerator pedal release speed increases by suddenly releasing the accelerator pedal and pressing the brake pedal in the case of sudden braking.

  While the vehicle is moving forward in step S120, if the mode switch is running on the road in step S121 and the accelerator pedal is released in step S122 and the brake pedal is depressed in step S123, the release speed of the accelerator pedal in step S124 is faster than the predetermined speed. For example, control is performed to reduce the speed ratio of the power roller 24 in step S125, and the control is stopped in step S127. If the release speed of the accelerator pedal is slower than the predetermined value in step S124, the control of the power roller 24 is normally controlled in step S126 while the output torque is increased, and stopped in step S127.

FIG. 20 shows a sudden braking determination based on the release speed of the accelerator pedal as in the control of FIG. 19, and the difference is that the release angular speed of the accelerator pedal is determined in step S <b> 124.
FIG. 21 shows control for determining sudden braking when a reverse driving torque of a predetermined level or more is sensed by utilizing the fact that torque acts on the axle of the driving wheel in the direction opposite to the driving direction during braking.

  During forward travel in step S140, if the brake connection sensor is ON in step S141 and braking is performed with the brake pedal in step S142, the axle torque is measured in step S143, and the reverse drive torque of the measured axle torque is predetermined in step S144. If greater than the value, control is performed to reduce the speed ratio of the power roller 24 in step S145, and the control is stopped in step S147. If the reverse driving torque of the axle torque is equal to or less than the predetermined value in step S144, the control is performed in step S147 while the output torque is increased in the normal manner in step S146, while the output torque is increased.

FIG. 22 shows the sudden braking determination by measuring the axle torque as in the control of FIG. 21. The difference is that it is determined in step S151 that the traveling mode is traveling.
FIG. 23 shows sudden braking control with axle torque in reverse travel. During reverse travel in step S160, when braking with a brake pedal is detected in step S161, the axle torque is measured in step S162, and this measurement is performed in step S163. If the driving torque of the axle torque is larger than a predetermined value, control is performed so as to reduce the speed ratio of the power roller 24 in step S164, and the control is stopped in step S166. If the driving torque of the axle torque is less than or equal to the predetermined value in step S163, in step S165, the control of the power roller 24 is normally performed and the output torque is increased while stopping in step S166.

  FIG. 24 is a control in which the traction force is measured when the trailer is towed by the tractor, and the braking is performed when the traction force is switched to the pressing force and is stronger than the predetermined pressure. If the brake connection sensor is ON in step S171 and braking is performed by the brake pedal in step S172, the traction force of the trailer is measured in step S173, and if the measured traction force is a pressing force and the pressing force is greater than a predetermined value in step S174. In step S175, the power roller 24 is controlled to decelerate the gear ratio, and stopped in step S177. If the pressing force is equal to or less than the predetermined value in step S174, the control of the power roller 24 is normally performed in step S176, and the output torque is increased as usual, and then stopped in step S177.

FIG. 25 is a sudden braking determination by measuring the traction force as in the control of FIG. 24, and the difference is that it is determined in step S181 that the traveling mode is traveling.
FIG. 26 shows the sudden braking control with the traction force in the reverse travel. When the brake pedal is detected in the step S191 during the reverse travel in the step S190, the traction force is measured in the step S192. If it is larger than the predetermined value, control is performed so as to reduce the speed ratio of the power roller 24 in step S194, and the process is stopped in step S196. If the driving torque of the axle torque is equal to or less than the predetermined value in step S193, the control is performed in step S196 while the output torque is increased in the normal manner in step S195, while the output torque is increased.

FIG. 27 shows the control when the brake pedal is depressed during reverse travel in the constant vehicle speed mode. When one brake is depressed for turning, the vehicle speed is changed to a low speed so that the vehicle can safely turn.
If the mode condition in step S201 is the constant vehicle speed mode and the vehicle is moving backward in the traveling direction condition in step S202 and the brake is depressed in step S203, the left and right brakes are connected in the brake connection determination in step S204. In step S205, the target vehicle speed is set to zero and stop processing is performed. In step S204, if the left and right brakes are not connected, the target vehicle speed is changed to low speed and turning processing is performed. If the brake is not depressed in step S203, the vehicle continues traveling with the constant vehicle speed control in step S207. If it is not the constant vehicle speed mode in step S201, the process proceeds to another control mode (such as a constant torque mode) in step S208.

FIG. 28 shows the control in the constant vehicle speed mode, and when the left and right brakes connected in reverse are depressed, the constant vehicle speed mode is canceled.
If the constant vehicle speed mode is selected in step S210, the flag which is a signal of the constant vehicle speed mode is set to 1 in step S211, and if the linear shift lever is advanced in step S212, the constant vehicle speed mode is controlled in step S213. If the linear shift lever is reverse in step S212, the determination that the brake pedal is depressed in step S214 and the brake connection in step S215 is both yes, and the constant vehicle speed mode is canceled, and either step S214 or step S215 is no. If there is, control as a constant vehicle speed mode. If it is not the constant vehicle speed mode in step S210, the process proceeds to another control mode in step S218.

FIG. 29 shows the control in the constant ratio mode that fixes the speed ratio of the power roller. When the left and right brakes that are connected in reverse are depressed, the constant ratio mode is canceled.
If the constant ratio mode is selected in step S220, the flag which is a signal of the constant ratio mode is set to 1 in step S221. If the linear shift lever is advanced in step S222, the control is set to the constant ratio mode in step S223. If the linear shift lever is reverse in step S222, the determination that the brake pedal is depressed in step S224 and the determination that the brake is engaged in step S225 are both yes, and the constant vehicle speed mode is released, and either step S214 or step S215 is no. If so, control as a constant ratio mode. If it is not the constant ratio mode in step S220, the process proceeds to another control mode in step S228.

  FIG. 30 shows the control when the brake pedal is depressed during reverse travel in the constant ratio mode. When one brake is depressed for turning, the target variator ratio is changed to a low speed so that the vehicle can turn safely.

  If the mode condition in step S231 is the constant ratio mode and the vehicle is moving backward in the traveling direction condition in step S232 and the brake is depressed in step S233, the left and right brakes are connected in the brake connection determination in step S234. Then, in step S235, the target variator ratio → GN (geared neutral) is set to stop processing, and in step S234, if the left and right brakes are not connected, the target variator ratio is changed to low speed and turning processing is performed. If the brake is not depressed in step S233, the traveling is continued by the constant ratio control in step S237. If it is not the constant ratio mode in step S231, the process proceeds to another control mode (such as a constant torque mode) in step S238.

It is a sectional side view of the mission case which implemented this invention. It is front sectional drawing of the mission case which implemented this invention. It is a power transmission system diagram in a mission case. It is a partially expanded side sectional view of a mission case. It is a partial enlarged side sectional view. It is a partial enlarged side sectional view. It is a control block diagram. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure. It is a control flowchart figure.

Explanation of symbols

1 Mission case 4 Toroidal speed change mechanism 10 Variator shaft BS Braking judgment signal

Claims (5)

In the configuration in which the toroidal speed change mechanism (4) is incorporated in the power transmission unit that drives the traveling wheel drive of the work vehicle, there is provided traveling mode switching means for selecting and setting the working traveling mode or the road traveling mode. The switching means is set to the road traveling mode, or the condition in which the forward / reverse switching means provided in the power transmission portion is set to the reverse traveling side, and the brake operation state of the work vehicle or the operation state accompanying the braking A continuously variable transmission control device for a work vehicle, which is configured to control the output of the toroidal transmission mechanism (4) to a deceleration side based on a condition for inputting a braking determination signal (BS) based on the condition. 2. The continuously variable transmission control device for a work vehicle according to claim 1, wherein the brake determination signal (BS) is input when a deceleration due to braking of the work vehicle exceeds a predetermined value. 2. The continuously variable transmission control device for a work vehicle according to claim 1, wherein the brake determination signal (BS) is input when the steering rotational speed exceeds a predetermined value. 2. The continuously variable transmission control device for a work vehicle according to claim 1, wherein the brake determination signal (BS) is input when the brake pedal depression speed or depression angle exceeds a predetermined value. 2. The continuously variable transmission control device for a work vehicle according to claim 1, wherein the brake determination signal (BS) is input when the engine speed or the speed reduction rate exceeds a predetermined value. .

Images