JP2009180232A - Continuously variable transmission type working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuously variable transmission type working vehicle which can keep the operability of an accelerator pedal adapted to a running mode of the working vehicle. <P>SOLUTION: The continuously variable transmission type working vehicle includes an accelerator pedal 5f for forward running for operating forward running vehicle speed and an accelerator pedal 5r for backward running for operating an operation of backward running vehicle speed, a control section 7 deciding a target speed change position of trunnion shaft along a predetermined development property for matching with operations of these accelerator pedals, and a continuously variable speed change adjusting section 1d changing vehicle speed by controlling a hydro-static continuously variable speed change mechanism 1 by driving the trunnion shaft to the target speed change position. The control section 7 has a commonly set development property and an individually set development property to both accelerator pedals 5f, 5r for the forward running and the backward running, and these common and individual development properties can be changed by a signal of a selector switch S. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a continuously variable work vehicle that can adjust a vehicle speed steplessly according to a pedal depression amount.

As shown in Patent Document 1, there is known a continuously variable work vehicle that continuously controls a vehicle speed by driving and controlling a trunnion shaft of a hydrostatic continuously variable transmission mechanism according to a depression amount of a vehicle speed adjusting pedal. . In this continuously variable work vehicle, the traveling direction is switched by a forward / reverse lever, and the traveling vehicle speed can be operated by an accelerator pedal for adjusting the vehicle speed.
JP 2005-343187 A

  However, in general, the vehicle speed of the work vehicle during forward traveling is uniformly used over the entire vehicle speed range, and the low-speed range is frequently used during backward travel. Since the required vehicle speed range is also different, a situation in which a delicate pedal operation is required to adjust to the required vehicle speed occurs. This is the same not only when the traveling direction is changed but also when the vehicle speed band is changed by the auxiliary transmission mechanism.

  The problem to be solved is to provide a continuously variable work vehicle capable of ensuring the operability of an accelerator pedal adapted to the traveling mode of the work vehicle.

  According to the first aspect of the present invention, a forward accelerator pedal for operating the forward travel vehicle speed, a reverse accelerator pedal for operating the reverse travel vehicle speed, and predetermined operations for associating these accelerator pedal operations with each other. A control unit that determines the target shift position of the trunnion shaft in accordance with the development characteristics, and a continuously variable transmission adjustment unit that changes the vehicle speed by controlling the hydrostatic continuously variable transmission mechanism by driving the trunnion shaft to the target shift position. In the continuously variable work vehicle having the above, the control unit has a common setting deployment characteristic and an individual set deployment characteristic for both the forward accelerator pedal and the reverse accelerator pedal. The application of the characteristics is characterized in that it can be switched by the signal of the selector switch.

  By the above control, in addition to the common development characteristics for the forward and reverse accelerator pedals, the development characteristics for each traveling direction corresponding to the pedal are applied by the switch operation.

  According to a second aspect of the present invention, a control unit that determines a target shift position of the trunnion shaft in accordance with a predetermined development characteristic for association with an operation of an accelerator pedal, and driving the trunnion shaft to the target shift position. A continuously variable transmission including a continuously variable transmission adjusting unit that changes a vehicle speed by controlling a hydrostatic continuously variable transmission mechanism, and a sub-transmission mechanism that switches a vehicle speed band by serial transmission with the hydrostatic continuously variable transmission mechanism. In the shift work vehicle, the control unit has a development characteristic for each vehicle speed band of the sub-transmission mechanism, and determines a target shift position of the trunnion shaft based on the development characteristic according to the switched vehicle speed band.

  By the above-described control, the development characteristics for each vehicle speed band are applied corresponding to the switching of the auxiliary transmission mechanism, so that the vehicle speed can be adjusted by the pedal operation corresponding to each vehicle speed band.

  In the continuously variable work vehicle according to the first aspect, in addition to a common deployment characteristic for the forward accelerator pedal and the reverse pedal, a deployment characteristic for each traveling direction corresponding to the pedal is applied by a switch operation. Because it is possible to realize pedal operability for adjusting the vehicle speed by developing characteristics according to the driving mode, it is possible to ensure pedal operability suitable for forward travel using the entire range and reverse travel using the low speed range frequently. it can.

  In the continuously variable work vehicle according to the second aspect, the development characteristics for each vehicle speed band are applied by switching the sub-transmission mechanism. Therefore, the pedal operability for adjusting the vehicle speed according to the traveling mode of the vehicle speed band is provided. The pedal operability suitable for the switched vehicle speed band can be ensured.

Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings.
A multipurpose work vehicle as an example of a continuously variable work vehicle to which the present invention is applied will be described. As shown in FIG. 1, a plan view (a) and a side view (b) of this work vehicle are monocoque. The left and right front wheels 8 and 8 and the left and right rear wheels 9 and 9 are supported on the frame so that they can be steered. Place in the front. The control part 2d is formed at the front part of the machine body, the loading platform 2t is formed at the rear part, the PTO shaft 13 is provided at the front part of the machine body as working machine power, and the vehicle height detection mechanism 2h is formed in a drooping manner at the machine body intermediate position. .

  Further, as shown in FIG. 1 (c), the steering unit 2d is provided with a steering column R by standing up a handle column 2c, and the base of the handle column 2c is advanced to the right side thereof. Further, accelerator pedals 5f and 5r for adjusting the vehicle speed of the reverse drive, and operating means such as a brake pedal B and a clutch pedal C are arranged on the left side.

  As will be described in detail later, the transmission 14 includes a hydrostatic continuously variable transmission mechanism 1 and a gear-type transmission mechanism 14 a, which are abbreviated as “HST”, provided in series so that the front and rear wheels 8 and 9 and the PTO output shaft 13 Transmits driving force. When the accelerator pedals 5f and 5r that are moved forward and backward are stepped on, the power from the engine 6 is changed by the continuously variable transmission mechanism 1 in the transmission 14, and further changed by the transmission mechanism 14a, so that the rear wheels 9, 9 or the rear wheels are changed. 9 and 9 and the front wheels 8 and 8, the aircraft moves forward or backward. Further, when the brake pedal B is depressed, the disc brakes (not shown) of the front wheels 8, 8 and the rear wheels 9, 9 are actuated, and the trunnion shaft H of the variable hydraulic pump of the HST is returned to the neutral position. Stops output from. If the accelerator pedals 5f and 5r and the brake pedal B are depressed at the same time, the brake pedal B is given priority.

  Various work machines are connected to the PTO shaft 13 to enable multipurpose work. For example, a road cleaning machine is provided to perform road cleaning, a lawn mower is attached to perform lawn mowing work, or a snow plow is provided to perform snow removal work.

Next, the internal structure of the mission case 14 will be described with reference to FIGS.
As shown in FIG. 2, the transmission case 14 has a configuration in which four hollow cases of a front case 15, a connecting case 16, an intermediate case 17, and a rear case 18 are connected. , The rotation of the input shaft 19 is transmitted to the first relay shaft 23 by the speed increasing gears 21 and 22 in the input case 20, and further increased by the speed increasing gears 24 and 25. The hydraulic input shaft 38 of the continuously variable transmission mechanism 1 is spline fitted to the gear 25. The connecting case 16 connects the conventional front case 15 and the intermediate case 17 to lengthen the mission case 14, and the front case 15, the intermediate case 17, and the rear case 18 are shared with the conventional mission case, so that the production cost is increased. Can be lowered.

  The input case 20 including the speed increasing gears 21 and 22 and the speed increasing gears 24 and 25 is provided to increase the output rotation speed of the engine 6 so as to enable high speed travel. The transmission mechanism can be accommodated in 14. As shown in FIG. 4, if the input case 20 is a sealed case and oil is supplied from an oil supply pipe that leads to the outside of the transmission case 14, the transmission gears 21, 22, 24, and 25 are repaired when the transmission is repaired. Since only the input case 20 can be removed without draining the oil in the case 14, the work becomes easy.

Inside the continuously variable transmission mechanism 1, the output is largely steplessly changed by hydraulic transmission and is output to two shafts of the PTO drive shaft 26 and the travel drive shaft 27.
A PTO gear shaft 28 is connected to the PTO drive shaft 26, a gear 29 of the PTO gear shaft 28 and a gear 31 loosely fitted to the second relay shaft 30 are engaged, and a PTO clutch in which the gear 31 is mounted on the PTO shaft 32. It meshes with 34 gears 33. The PTO clutch 34 interrupts rotation transmission from the gear 33 to the PTO shaft 32.

A PTO extension shaft 35 is connected to the PTO shaft 32, and a gear 36 of the PTO extension shaft 35 is engaged with a clutch gear 37 spline-fitted to the PTO output shaft 13 to drive the PTO output shaft 13. (See Figure 2)
The details of the PTO clutch 34 are shown in FIG. 5. When the clutch is engaged, the clutch disc 88 is connected and the casing 86 is rotated and transmitted. However, when the clutch is disengaged, the clutch disc 88 is separated by the pressure of the return spring 87 and the casing 86 is separated. Make it free. At this time, a locking ring 85 that contacts the boss 81 of the connecting case 16 is attached to the outer periphery of the casing 86 in order to prevent the casing 86 from being attached.

  A third relay shaft 39 is connected to the travel drive shaft 27, and gears 41 and 42 fixed to the third relay shaft 39 are engaged with each other and transmitted to the fourth relay shaft 43. A main gear shaft 44 is connected to the fourth relay shaft 43.

A large gear 45 and an intermediate gear 46 are integrally fixed to the main gear shaft 44, and a sub gear shaft 47 is separated and supported rotatably on the extension of the main gear shaft 44. A small gear 48, a large gear 74, and a traveling transmission gear 75 are integrally fixed to the sub gear shaft 47. Accordingly, the large gear 45 and the middle gear 46 rotate in the same direction, and the small gear 48, the large gear 74, and the travel transmission gear 75 receive rotation from a clutch gear 77 described later. (See Figure 5)
The large gear 45 meshes with the gear 50 of the high-speed hydraulic clutch YH attached to the clutch shaft 49, the middle gear 46 meshes with the gear 53 of the low-speed hydraulic clutch YL attached to the clutch shaft 49, and the rotation of the main gear shaft 44 causes the clutch shaft 49 to rotate. To high speed or low speed.

  A spline shaft 76 is spline-fitted on the extension of the clutch shaft 49, and a clutch gear 77 is spline-fitted on the spline shaft 76 to transmit the rotation of the clutch shaft 49 to the clutch gear 77. Further, the boss portion 81 of the connecting case 16 that supports the clutch shaft 49 is provided with hydraulic holes 82, 83, 84 that communicate with the hydraulic holes of the clutch shaft 49, and hydraulic oil is supplied to the high-speed hydraulic clutch 51 and the low-speed hydraulic clutch 52. I am trying to send it.

  A large gear 78 and a small gear 73 are formed in the clutch gear 77, and the large gear 78 meshes with the small gear 48 of the sub gear shaft 47 to increase the transmission speed to form a high speed gear clutch GH, or the small gear 79 is a sub gear. The low speed gear clutch GL is configured by meshing with the large gear 74 of the shaft 47 and decelerating, or the gear transmission clutch 3 is configured such that the large gear 78 and the small gear 79 are both turned to turn off the power. Yes.

  The travel transmission gear 75 of the clutch shaft 49 is engaged with the travel gear 56 spline-fitted to the bevel gear shaft 62 loosely fitted to the spline shaft 76 to drive the bevel gear shaft 62. The bevel gear 63 of the bevel gear shaft 62 transmits the driving force to the bevel gear attached to the axle of the front wheel 8.

  The bevel gear shaft 62 is a four-speed transmission from the high speed hydraulic clutch YH to the large gear 78 of the clutch gear 77 and the small gear 48 of the sub gear shaft 47, or the small gear 79 of the clutch gear 77 and the sub gear shaft 47 of the sub gear shaft 47. Third gear by transmission to the large gear 74, second gear by transmission from the low speed hydraulic clutch YL to the large gear 78 of the clutch gear 77 and the small gear 48 of the sub gear shaft 47, or small gear of the clutch gear 77 from the low speed hydraulic clutch YL. 79 and the sub gear shaft 47 are rotated at any one speed by transmission to the large gear 74.

  Further, the rotation of the bevel gear shaft 62 is transmitted from the traveling gear 56 to the small gear portion 57 of the large and small gear 59 attached to the PTO shaft 32, and is further appropriately controlled by the clutch gear 60 of the rear wheel drive shaft 61 engaged with the large gear portion 58. The driving force can be transmitted to the rear wheel 9.

Since the traveling gear 56 is transmitted to the bevel gear shaft 62 and is transmitted to the rear wheel drive shaft 61 via the large and small gears 59, the transmission configuration is simplified to prevent it from becoming longer in the front-rear direction.
Note that either the high-speed hydraulic clutch YH or the low-speed hydraulic clutch YL is kept on via a solenoid in response to a control signal from the controller. A switch B for detecting depression of the brake pedal is provided. In response to the depression signal, the power to the solenoids of the high-speed hydraulic clutch YH and the low-speed hydraulic clutch YL is cut off so that both clutches 51 and 52 are neutral. By applying the brake in this neutral state, it can be quickly stopped and the gear shift clutch 3 can be switched smoothly.

  The boss portion 81 of the connecting case 16 that supports the clutch shaft 49 is provided with hydraulic holes 82, 83, 84 that communicate with the hydraulic holes of the clutch shaft 49, and hydraulic oil is supplied to the high-speed hydraulic clutch YH and the low-speed hydraulic clutch YL. I am trying to send it.

  FIG. 6 shows the shift lever 4, and the gear shift clutch 3 is shifted to the high-speed gear clutch or the low-speed gear clutch by rotating the shift groove 96 from the center neutral position N to the front and rear H and L. When the speed increasing button 81 provided on the head of the grip 80 of the speed change lever 4 is pressed, the high speed hydraulic clutch YH is engaged, and when the speed reducing button 82 is pressed, the low speed hydraulic clutch YL is engaged.

  In addition, sensors 90H and L for detecting the position of the speed change lever 4 are provided in the speed change groove 96 so that when the speed change lever 4 moves from the low speed position L to the high speed position H, the high speed hydraulic clutch YH is turned off. When the low-speed hydraulic clutch YL is turned on to become the third speed and moved from the high speed position H to the low speed position L, the low-speed hydraulic clutch YH is turned on even if the low-speed hydraulic clutch YL is turned on, and the second speed The microcomputer is controlled so that When the high-speed hydraulic clutch YH is engaged, if the accelerator pedals 5f and 5r are depressed 3/4 or more and the continuously variable transmission mechanism is at a high speed, the speed is reduced once to reduce the shift shock. Further, when the lever 4 presses the deceleration button 82 at the low speed position L, the first speed is achieved, and when the lever 4 presses the acceleration button 81 at the high speed position H, the fourth speed is achieved.

(Shift control)
Next, the shift control will be described.
As shown in FIG. 7, the shift control of the work vehicle includes a position sensor 5a for the accelerator pedals 5f and 5r, a position sensor Ba for the brake pedal B, a position sensor Ca for the clutch pedal C, a changeover switch S, and the like. The operation tool detection signal and the device operation detection signal are input to the control unit 7 and are output to the vehicle speed adjustment unit 1d of the continuously variable transmission mechanism 1 and the engine control controller 6c in accordance with the input signals. The accelerator pedal is composed of forward and reverse individual pedals 5f and 5r. The brake pedal B is configured to be capable of split operation for the left brake and the right brake. The continuously variable transmission mechanism 1 performs forward / reverse switching and stepless transmission ratio adjustment by a vehicle speed adjusting unit 1d that adjusts the trunnion shaft H by electric or hydraulic rotation, adjusts the traveling vehicle speed through the transmission system, and adjusts the engine 6 Supplies the necessary traveling power and working machine power by the controller 6c.

  More specifically, the control unit 7 sets the target shift position of the trunnion shaft H along a predetermined deployment characteristic (pedal deployment type) for associating pedal operation with the accelerator pedals 5f and 5r for forward and reverse travel. To decide. As shown in FIG. 8, the control unit 7 includes a forward development characteristic C1 for the forward accelerator pedal 5f and a forward development characteristic C2 for the reverse accelerator pedal 5r. Use individual deployment characteristics. In this case, by providing a changeover switch S for using the forward development characteristic C1 for the reverse accelerator pedal 5r, it is possible to make the development characteristics common to both pedals 5f and 5r. The “pedal angle” on the horizontal axis of the development characteristic diagram corresponds to the pedal depression amount, and the “trunion angle” on the vertical axis is the angle difference from the neutral position and corresponds to the vehicle speed.

  As shown in the flowchart of FIG. 9, the control process in the case of applying the individual development characteristics described above is determined by the pedal position determination (S2) following the sensor and switch reading process (S1). If it is “forward,” the trunnion target is calculated based on the forward characteristic C1 (S3a), and if not applicable, the trunnion target is calculated based on the reverse characteristic C2 (S3b). The section 1d drives the trunnion shaft H and controls the hydrostatic continuously variable transmission mechanism 1 to change the vehicle speed.

  By the shift control of the control unit 7, in addition to the common development characteristic C1 for the forward accelerator pedal 5f and the reverse accelerator pedal 5r, the development characteristic for each traveling direction corresponding to the pedal is applied by the switching operation of the changeover switch S. Therefore, the pedal operability for adjusting the vehicle speed by the development characteristics according to the forward and reverse traveling modes can be realized. For example, the forward side uses the entire vehicle speed range (trunnion angle range) evenly, so it is spread evenly, and the reverse side is often used at slow vehicle speeds, so it is suitable for each by expanding the part where the trunnion angle is small widely The pedal operability can be secured.

  Another example of the shift control corresponding to the sub-transmission mechanism will be described. When the sub-transmission mechanism in series with the continuously variable transmission mechanism 1 is set to the third speed of “high speed”, “medium speed”, and “low speed”, the controller 7 As shown in FIG. 10, the development characteristic diagram includes a development characteristic C3 at high speed corresponding to switching of the sub-transmission mechanism and a development characteristic C4 at low speed and medium speed. In the control process, as shown in the flowchart of FIG. 11, the trunnion target is calculated (S12a) based on the high-speed characteristic C3 if it is “high speed” based on the determination of the sub-shift position (S11). By calculating the trunnion target based on the characteristic C4 at the time of low speed and medium speed (S12b), the continuously variable transmission adjusting unit drives the trunnion shaft H to control the hydrostatic continuously variable transmission mechanism 1 at this target shift position. Change the vehicle speed.

  With the above speed change control, the sub-speed “high speed” is used for road driving, etc., and “medium speed” and “low speed” are used for field work. Thus, the resolution can be increased in the required vehicle speed range.

(For brake)
Next, the shift control reflecting the brake operation will be described.
Brake sensor Ba using a switch or the like for detecting depression of brake B is provided, and control processing for changing the trunnion target to the deceleration side when brake B is depressed for a predetermined time or longer as shown in the flowchart of FIG. 12 (S21, S22) By configuring this, the drive wheel is decelerated only when the brake depression operation is continued for a predetermined time. In this way, in a tractor having a configuration in which the power interruption in the traveling transmission system is limited to the neutral operation of the auxiliary transmission lever, an operation for stopping the traveling due to a failure of the sensor 5a of the accelerator pedals 5f and 5r for operating the forward and backward movement of the airframe. When the means is lost, the brake pedal B enables emergency response transmission control, so that safety can be improved.

  Further, in the above control configuration, by detecting the depression amount of the brake B with a potentiometer or the like and changing the deceleration amount of the trunnion target according to the depression amount of the brake B, it is possible to avoid unnecessary deceleration. . As shown in the flowchart of FIG. 13, when the trunnion target TR is determined by the pedal operation and the brake sensor value A is obtained by the brake operation (S31), the detailed control corresponding to the brake depression amount is performed by the brake sensor value A. When the depression is determined, the trunnion target is changed to TR × f (A) (S32, S33). In this case, f (A) is a coefficient for reducing the trunnion target by the brake depression amount A as shown in the diagram of FIG.

  Further, in the above control configuration, in order to ensure safety according to the degree of urgency, as shown in the flowchart of FIG. 15, the change of the trunnion H to the deceleration position according to the stepping change speed of the brake B (S41, S42) The speed is changed (S43a, S43b). By this shift control, the trunnion H can be quickly changed to the deceleration side when an emergency stop is required to avoid danger.

  Further, the shift control by the brake operation is configured as a control (S51, S52) on condition that the left and right brake pedals are connected, as shown in a flowchart in FIG. With such a control configuration, the application is canceled at the time of field work that requires a one-brake operation, and the transmission of the traveling transmission system is maintained even by the brake operation, so that the work traveling can be continued without any problem.

Next, the return process after the deceleration process by the shift control will be described.
As shown in the flowchart of FIG. 17, in the shift control for the return process after the deceleration, the return output (S62) is executed on the condition that the return condition is satisfied (S61). The return output is the accelerator pedal 5f, By performing stepwise up to the trunnion target position corresponding to 5r, it is possible to avoid re-deceleration that occurs when returning rapidly, that is, re-deceleration that occurs due to fluctuations in engine rotation accompanying rapid acceleration.

  If necessary, the return output is gradually performed while monitoring the engine rotation, and when the decrease in engine rotation is suppressed within a certain value, the return output is output when the trunnion H is returned to the original position. Cancel (S63, S64). In this way, by performing the return output while monitoring the engine rotation, it is possible to avoid a situation in which the deceleration is repeated again when returning to the original position when the high load state continues.

(Clutch function)
Next, a clutch function pedal for urgently stopping the airframe traveling will be described.
To stop traveling when a failure occurs in the trunnion drive system including the trunnion sensor when no mechanical clutch is provided in the traveling transmission system, the engine 6 is turned off, stalled, or the sub-shift is operated neutrally. There was a problem that both of them were necessary and incurred danger in time for drought. In order to solve the problem, a clutch function pedal C is provided, and the engine is stopped by depressing the pedal C. Thus, the clutch is disengaged and the brake is depressed for emergency stop. The same effect as the case can be obtained, and safety can be ensured.

  Further, by providing a sensor for detecting the depression amount in the clutch function pedal C, and configuring the shift control to change the trunnion target to the deceleration side according to the depression amount, as shown in the depression characteristic diagram of FIG. Since the deceleration operation is performed according to the depression amount of the pedal C in a situation where there is no abnormality in the trunnion relationship, it is possible to use a mode including a so-called “half clutch” like a mechanical clutch.

  Further, the clutch function pedal C is provided with a full depression sensor such as a switch for specially detecting the full depression operation, and as shown in the flowchart of FIG. 19, the trunnion target is neutral (S71) at the time of the detection. By performing the shift control, safety can be ensured through reliable control of two stands together with the sensor for detecting the stepping motion.

  Further, by configuring a control process for stopping the engine (S72, S73) on condition that the full depression state by the full depression sensor has continued for a specified time following the shift control, the aircraft can be immediately operated by the full depression operation. Since it can be stopped, the clutch function pedal C can be used for emergency stop for ensuring safety.

  Further, as shown in a flowchart of another control process in FIG. 20, by configuring the control process for stopping the engine (S81, S82) on the condition of operation of the brake pedal B, instead of the engine stop condition in the control process. Since the function equivalent to the mechanical clutch is ensured and the emergency stop is possible only by simultaneous operation with the brake pedal B, the versatility of the pedal can be ensured.

(Maximum vehicle speed control)
Next, the maximum vehicle speed control will be described.
When the vehicle body maximum speed (for example, 40 km / h) defined as the vehicle specification is exceeded, a control chart for the maximum vehicle speed control is shown in FIG. 21 when the vehicle speed sensor V returns the traveling vehicle speed to the vehicle body maximum speed. By configuring the control to drive the trunnion shaft H to the deceleration side until T, it is possible to avoid a dangerous situation especially on a curve or the like because the vehicle speed increases without the operator noticing due to downhill traveling or the like.

  In addition, as shown in FIG. 22, a control chart for another maximum vehicle speed control, instead of the above trunnion shaft control, the engine speed is reduced on the low speed side until the time T when the traveling vehicle speed returns to the maximum body speed by the vehicle speed sensor V. By controlling the speed, it is possible to avoid the danger caused by high speed and to obtain an energy saving effect by suppressing the fuel consumption.

Plan view (a), side view (b) and main part perspective view (c) of multi-purpose work vehicle Transmission axis development Fig. 2 is an exploded view of the main axis of the transmission of Fig. 2 FIG. 2 is an enlarged view of a continuously variable transmission portion of the transmission of FIG. FIG. 2 is an enlarged view of the transmission mechanism of the transmission of FIG. Perspective view of transmission lever Shift diagram of work vehicle shift control system Development characteristics diagram of shift control Flowchart by shift control of FIG. Development characteristics diagram of another shift control FIG. 10 is a flowchart according to the shift control. Brake operation control flowchart Flow chart of brake depression amount control Diagram showing an example of the coefficient f (A) Flow chart of emergency response control Flow chart when application is limited when traveling on the road Flow chart of shift control for return processing Depression characteristic diagram Flowchart when pedal is fully depressed Flow chart of another control process Maximum vehicle speed control chart Control chart of different maximum vehicle speed control

Explanation of symbols

1 Hydrostatic continuously variable transmission mechanism (HST)
1d Vehicle speed adjusting unit 5f Forward accelerator pedal 5r Reverse accelerator pedal 6 Engine 7 Control unit A Depression amount B Brake pedal C Clutch pedals C1 to C4 Deployment characteristics f Reduction factor H Trunnion shaft S Changeover switch

Claims (2)

The forward accelerator pedal (5f) for operating the forward travel vehicle speed, the reverse accelerator pedal (5r) for operating the reverse travel vehicle speed, and predetermined development characteristics for associating these accelerator pedal operations with each other And a control unit (7) for determining a target shift position of the trunnion shaft (H) along the line and driving the trunnion shaft (H) to the target shift position to control the hydrostatic continuously variable transmission mechanism (1). A continuously variable transmission work vehicle comprising a continuously variable transmission adjusting unit (1d) that changes the vehicle speed by
The control section (7) has a common development characteristic (C1) and individual development characteristics (C1, C2) for both the forward and reverse accelerator pedals (5f, 5r). A continuously variable work vehicle characterized in that the application of the development characteristics can be switched by a signal of a changeover switch (S). A control unit (7) for determining a target shift position of the trunnion shaft (H) in accordance with a predetermined development characteristic for association with the operation of the accelerator pedal, and driving the trunnion shaft (H) to the target shift position The vehicle speed band is switched by serial transmission of a continuously variable transmission adjusting unit (1d) that changes the vehicle speed by controlling the hydrostatic continuously variable transmission mechanism (1) and the hydrostatic continuously variable transmission mechanism (1). In the continuously variable work vehicle having a sub-transmission mechanism that performs the above, the control unit (7) has a deployment characteristic for each vehicle speed band of the sub-transmission mechanism, and the trunnion shaft has a deployment characteristic corresponding to the switched vehicle speed band A continuously variable work vehicle characterized by determining a target shift position of (H).

Images