JP4951998B2 - Tractor shift control device - Google Patents

Description

  The present invention provides a shift control function for switching and controlling the main transmission unit to the main shift position of the longest use according to the accumulated use time stored in advance by switching the sub shift lever to the shift position for shift transmission according to the vehicle speed range. The present invention relates to a tractor shift control device having (memory shift).

As shown in Patent Documents 1 to 3, there is known a tractor shift control device that performs automatic shift control by memory shift.
The above-mentioned memory shift calculates the cumulative usage time for each shift position of the main transmission when traveling with the tractor's vehicle speed adjusted according to the work contents, for each operation position of the sub-shift lever for selecting the vehicle speed range. The shift control is performed to the longest used main shift position in the selected vehicle speed range by the sub shift position sensor signal by the switching operation of the sub shift lever.

Therefore, by the above-mentioned memory shift, when the travel starts or during travel, the sub-shift lever is switched to select the vehicle speed range for the next work, so that the vehicle speed range is used. Since the vehicle can travel at the longest use vehicle speed, the work similar to the work at the longest use vehicle speed based on the past records can be efficiently resumed without requiring troublesome vehicle speed adjustment.
JP 2004-251351 A Japanese Patent Laying-Open No. 2005-9532 JP 2005-195052 A

  However, when the vehicle is traveling at a speed of the main shift position different from the memory shift by manually adjusting the vehicle speed according to the work situation, the sub-shift position sensor signal may be momentarily interrupted by vibration of the variable sub-shift lever, etc. Then, since the shift process by the memory shift accompanying the re-transmission of the auxiliary shift position sensor signal is performed, there is a possibility that an unexpected situation may be caused by a sudden change in the vehicle speed.

  The problem to be solved is that the shift control by the memory shift reflecting the operator's intention by the sub-shift lever operation is ensured, and the unexpected shift control due to the erroneous transmission of the sub-shift position sensor signal is avoided. It is an object of the present invention to provide a tractor shift control device that enables a good and stable running operation of a tractor.

According to the first aspect of the present invention, the sub-shift position sensor signal for detecting the switching operation of the sub-shift lever 25 to the shift position issues a shift command to the main shift position corresponding to the longest use according to the accumulated use time stored in advance, and is received. In a tractor shift control device including a shift control unit C that switches and controls the main transmission unit 1 in accordance with a shift command, the shift control unit C detects the previous sub shift position sensor signal again and follows the shift command. The application of the shift control for switching and controlling the main transmission unit 1 is based on the condition that the main clutch 40 for cutting off the traveling power from the engine E is being operated, and the multiple shift positions of the sub shift lever 25 are set. Each of them is characterized in that the weighting condition is that the vehicle speed is within the range corresponding to the stoppage of travel .

In the case where the immediately preceding sub-shift position sensor signal is detected again by the shift control unit, only when the predetermined application condition is met, that is, when the main clutch that cuts off the driving power from the engine is being operated. The shift control is applied. In addition, when the immediately preceding sub-shift position sensor signal is detected again, the shift is performed only when the shift speed of the sub-shift lever is within the vehicle speed range corresponding to the travel stop, in addition to the applicable condition by operating the clutch. Control is applied.

According to the second aspect of the present invention, the sub-shift position sensor signal for detecting the switching operation of the sub-shift lever 25 to the shift position issues a shift command to the main shift position corresponding to the longest use according to the accumulated use time stored in advance, and is received. In a tractor shift control device including a shift control unit C that switches and controls the main transmission unit 1 in accordance with a shift command, the shift control unit C detects the previous sub shift position sensor signal again and follows the shift command. Application of the shift control for switching and controlling the main transmission unit 1 is within the vehicle speed range corresponding to the travel stop set for each of the plurality of shift positions of the sub-shift lever 25, and the previous sub-shift position sensor signal is applied again. If it is detected, it is a condition that it is within a vehicle speed range corresponding to travel stop.

When the immediately preceding sub-shift position sensor signal is detected again by the shift control unit, the shift control is applied only when a predetermined application condition is met, i.e., within a vehicle speed range corresponding to travel stop. The Further, the shift control is applied according to the vehicle speed condition set corresponding to each of the plurality of shift positions of the sub-shift lever.

The tractor shift control device of the present invention has the following effects.
When the previous sub-shift position sensor signal is detected again by the shift control unit according to claim 1, the shift control is applied only when the main clutch is being operated by the operator. If the sub-shift lever is operated in parallel with the clutch operation, the shift control in accordance with the operator's intention is applied to control the switching to the longest used main shift position, while receiving the sub-shift position sensor signal again. However, if the above application conditions are not involved, the main shift position is maintained as it is without applying the shift control. Therefore, it is possible to efficiently and stably run the tractor while reliably reflecting the operator's intention and avoiding unexpected shift control due to erroneous transmission of the sub-shift position sensor signal. In addition, when the immediately preceding sub-shift position sensor signal is detected again, the shift control described above is applied only within the vehicle speed range corresponding to the travel stop, in addition to the application conditions by the operation of the clutch, based on the plurality of shift positions of the sub-shift lever. The Therefore, when the tractor is traveling, the shift control is applied only when the clutch is operated at the vehicle speed corresponding to the stoppage of travel due to the switching position of the sub-shift lever, so that sudden shifting during high-speed traveling is avoided and stable. It is possible to secure the running operation of the tractor.

When the previous sub-shift position sensor signal is detected again by the shift control unit according to claim 2, the shift control is applied only when the vehicle speed is within the range corresponding to the travel stop. If the sub-shift lever is operated when the vehicle speed is equivalent to running stop, the shift control is applied to control the switching to the longest used main shift position. When no condition is involved, the main shift position is maintained as it is without applying shift control. Accordingly, it is possible to avoid inappropriate shift control during high-speed traveling exceeding the stop equivalent vehicle speed and to efficiently and stably travel the tractor.
In addition, since the above shift control is applied according to the vehicle speed conditions corresponding to the plurality of shift positions of the sub-shift lever, a sudden shift during high speed traveling is avoided according to the vehicle speed situation, and stable traveling operation of the tractor is ensured. Can do.

Below, the form which mounted this invention on the agricultural tractor T used as a working vehicle is demonstrated.
FIG. 1 shows an overall side view of the tractor T. An engine E is mounted inside the hood 11 at the front of the vehicle body, and the rotational power of the engine E is transmitted to the main transmission unit 1 and the auxiliary transmission in the transmission case 12. The rotational power transmitted to the transmission unit 2 and decelerated by these transmissions is transmitted to the left and right front wheels 3F and 3F and the left and right rear wheels 3R and 3R as drive wheels.

  The governor mechanism G of the engine E includes an accelerator position sensor 13 that detects an accelerator position and an engine rotation sensor 14 that detects an output rotational speed.

  Further, a floor 16 on which the cockpit 15 is mounted is provided above the mission case 12, a handle post 17 is erected on the front portion of the floor 16, and a steering handle 18 is supported on the upper portion. A steering angle sensor 18s is provided as a means for detecting a turning operation of the vehicle.

  The handle post 17 includes an accelerator lever 20 (throttle lever) below the steering handle 18 and an accelerator pedal 21 on the floor 16 below the lever 20. Accordingly, the accelerator position of the engine E, that is, the rotation speed is set and held by holding the front / rear rotation position of the accelerator lever 20, and the engine rotation is performed in response to depression of the accelerator pedal 21 or release of the depression from the set position. The number can be increased or decreased.

  Further, the handle post 17 is provided with a forward / reverse switching lever 19 for switching the forward / backward traveling direction of the vehicle, and further provided with a clutch pedal 22 for turning on / off the main clutch 40 of the vehicle on the floor 16 near the post. It has become. A forward switch 19f and a reverse switch 19r for detecting the lever operating position are provided at the base of the forward / reverse switching lever 19, and a clutch pedal depression for detecting the depression of the pedal 22 is further provided at the base of the clutch pedal 22. The switch 22s is provided.

  A meter panel 23 having a liquid crystal monitor M and various display lamps is provided in front of the handle post 17.

Further, on the side of the cockpit 15 are equipped with various operation tools such as a sub-transmission lever 25 and a work implement elevating lever 26, and below this is equipped with a controller (transmission control section) C serving as control means of the present invention. It has a configuration.

  The sub-transmission lever 25 is an operating tool that shifts the sub-transmission unit 2 via the shift fork 55. As the operation position, “low speed” L speed, “medium speed” M speed, and “high speed”. It has the composition which has the following H speed. The speed change lever 25 is provided with an on-road H speed position for running on the road with an H speed transmission. These operation positions are detected by the sub-shift position sensors 25a, 25b, 25c, and 25d at the lever base.

  As a result, the main transmission unit 1 can be switched to the 1st to 8th speed shift positions, and the main transmission lever 25 is set to the L speed position, the M speed position, and the work H speed position for work travel. While the speed change can be switched over all 1 to 8 speeds, the main speed change range is set in the range from the 5th speed to the 8th speed in the state where the speed change lever 25 is set to the road H speed position. It has become. Thus, when traveling on the road, it is possible to reduce the number of shifts at the low speed position and quickly shift to the target shift position.

  The grip portion of the speed change lever 25 is provided with a speed change switch (speed increase switch, speed reduction switch) for switching the main speed change portion 1 having a speed change position from 1st speed to 8th speed one by one, and operates automatic speed change control. The shift control on / off switch for turning on / off is provided.

  In addition, a cylinder case 31 that houses a hydraulic cylinder 30 for raising and lowering the work implement is provided at the rear upper portion of the transmission case 12, and the piston of the hydraulic cylinder 30 is expanded and contracted by operating the work implement raising and lowering lever 26. The lift arms 32, 32 arranged on the left and right sides are configured to rotate up and down. The pivot bases of the lift arms 32, 32 are provided with a potentiometer type lift arm angle sensor 32s to detect the height of the work implement.

  In addition, a rear portion of the transmission case 12 includes a so-called three-point link mechanism including a top link 35 and left and right lower links 36, 36. The left and right lift arms 32, 32 are connected to the left and right lower links 36, 36. The other side is connected by a hydraulic cylinder 38 for working machine rolling.

  As a result, when the piston of the hydraulic cylinder for working machine rolling 38 is expanded and contracted, one side of the working machine can be moved up and down to control the right / left inclined posture of the working machine. In the example shown in the figure, the rotary tiller R is connected.

  FIG. 2 shows a power transmission diagram of the transmission mechanism of the tractor T. The rotational power of the engine E is first intermittently operated by the main clutch 40 and then transmitted to the forward / reverse switching unit 41, and further to the main drive. The transmission is transmitted in the order of the transmission unit 1 and the auxiliary transmission unit 2 and is transmitted to the rear wheels 3R and 3R via the rear wheel differential mechanism 42 or to the front wheels 3F and 3F via the front wheel drive shaft 43 and the front wheel differential mechanism 44. It has become.

  The forward / reverse switching unit 41 is a double hydraulic clutch transmission, detects the operating position of the forward / reverse switching lever 19 and operates the switching control valve according to the energization command of the controller C to advance the hydraulic clutch. 45 or the reverse hydraulic clutch 46 is turned on, and the rotational power from the engine E is switched between forward and reverse and transmitted to the main transmission 1.

  The main transmission unit 1 includes a first main transmission mechanism 1a and a second main transmission mechanism 1b. The first main transmission mechanism 1a is a synchromesh gear-type transmission that includes first to fourth transmission gear sets 47, 48, 49, and 50 in order from the front. One of the pistons of the first-second hydraulic cylinder 6a and the third-fourth hydraulic cylinder 6b, which are actuators, is driven to extend and contract, and rotational power is transmitted through one of the four gear sets. It is configured to transmit to the second main transmission mechanism 1b.

  The second main speed change mechanism 1b is a hydraulic clutch type speed change device having a high speed (Hi) clutch 51 and a low speed (Lo) clutch 52 and capable of two-stage switching. An internal piston serving as an actuator is driven, one of the clutches is pressure-bonded, and rotational power is transmitted to the auxiliary transmission unit 2.

  The auxiliary transmission unit 2 is a constant mesh gear type transmission that can switch between three speeds (L speed, M speed, and H speed). The transmission of the main clutch 40 is cut off, and the side of the cockpit 15 is The rotational power is transmitted to the rear wheel 3R or the front wheel 3F through a mechanical clutch mechanism through one of the speed change clutch or the speed change gear set by rotating the auxiliary speed change lever 25 in the front / rear / right / left direction. ing.

  As shown in the list of all the shift positions in the combination diagram of the main shift and the sub shift shown in FIG. 3 by the main transmission unit 1 and the sub transmission unit 2, the tractor T has eight main shift stages and three sub shift stages. Thus, a total of 24 shift positions can be obtained.

  Further, the power transmitted to the rear wheel differential mechanism 42 is also branched to the front wheel drive shaft 43 via the relay two-stage gear 56 provided on the upper side of the transmission, and this rotational power is increased by the front wheel acceleration on the coaxial 43. The speed is changed by the device 57 and transmitted to the front wheel differential mechanism 44.

  The front wheel speed increasing device 57 is a hydraulic clutch type speed change device that switches between high and low speeds having a constant speed clutch 58 and a high speed clutch 59. When the constant speed clutch 58 is pressure-bonded, the input rotation speed and the output rotation speed are increased. The number is the same, and the peripheral speed of the front wheel 3F is driven at substantially the same speed as the peripheral speed of the rear wheel 3R. The high-speed clutch 59 is a clutch that operates when the turning state of the vehicle is detected by the steering wheel turning angle sensor 18s. When the clutch 59 is pressed, the input rotational speed is approximately twice the output rotational speed. Then, the peripheral speed of the front wheel 3F is driven at twice the peripheral speed of the rear wheel 3R.

  Furthermore, if both the clutches 58 and 59 are in a non-compression state, the front wheel 3F is not driven and the tractor T is driven by two-wheel drive.

In the tractor T, the traveling drive mode is forcibly switched to the two-wheel drive state at regular intervals to detect the slip of the front and rear wheels, more specifically, on the upper transmission side and the lower transmission side of the front wheel speed increasing device 57. The slip state of the tractor T is detected by the detected values of the front and rear wheel rotation sensors 60r and 60f. When the slip is less than the allowable value, the tractor T is set to the rear wheel two-wheel drive state (2WD), and when the slip is large. The tractor T is configured to switch to a four-wheel drive state (4WD).
The lamp L is configured to appropriately display whether the vehicle is in the 2WD state or the 4WD state except when the slip is detected.

Next, the controller C will be described based on the control configuration diagram of FIG.
In the controller C, there are provided a CPU for processing various control information, an EEPROM serving as a storage device storing a control program for shift control of the present application, a RAM for temporarily storing various information, and a timer.

On the input side of the controller C, the speed increasing switch 4u and the speed reducing switch 4d provided in the grip portion of the sub speed change lever 25, the speed change control on / off switch 5 for turning on and off the memory speed change mode, and the operation of the sub speed change lever 25 are detected. auxiliary shift position sensor 25 a to 25 d, and more forward switch 19f, the backward switch 19r, clutch pedal depression switch 22s, the accelerator position sensor 21 a, an engine rotation sensor 14, wheel speed sensor 60f, a rear wheel rotation sensor 60r, a vehicle speed sensor 60, has a configuration for connecting the draft sensor 36 a will be described later.

On the output side of the controller C, a plurality of control valve solenoids 61, 61... For switching the main shift position, control valve solenoids 62f and 62r for switching the forward / reverse switching position, and a work machine lifting / lowering hydraulic cylinder 30 are extended and retracted. Then, solenoids 63a and 63b of control valves that move the lift arm 32 up and down, solenoids 64a and 64b of control valves that drive the working machine rolling hydraulic cylinder 38 to extend and contract, a liquid crystal monitor M, a buzzer 65, a display lamp L,. The various notification devices are connected.

  In the shift control, the memory count is stored in the EEPROM by measuring the time of the main shift position at each sub-shift position, and the accumulated use time of each main shift position is calculated as shown in the accumulated state diagram of the memory count in FIG. The main shift position with the longest accumulated usage time is controlled to be switched when the sub-shift lever is operated (hereinafter referred to as “memory shift”).

  Specifically, whether or not the lift arm angle sensor 32s detects that the position of the lift arm 32 is in the highest position, whether the lift arm 32 stops moving when the engine is started or the sensor is disconnected. It is determined whether or not the auxiliary transmission lever 25 is at the road H speed position, whether or not the clutch pedal 22 is depressed, and whether or not the forward / reverse switching lever 19 is in the reverse or neutral position. If even one of them has a corresponding determination, the tractor T is configured to interrupt the measurement assuming that it is in a non-working state. When all the above judgments are applicable and a predetermined time (for example, 1 minute) is continued, 1 is added to the memory count as a usage record.

  Further, the tractor T is configured so that it can be switched to all the main shift positions by a switch operation when the sub-shift position is set to the working H speed. The position is configured to measure only the position that can be used for work, and is excluded from the measurement at the main shift position (6th, 7th, and 8th speeds) on the high speed side assuming road travel. As a result, the high speed position is not selected when starting at the time of the work, and sudden start can be prevented.

Next, a specific application process of the memory shift will be described.
As shown in the flowchart of FIG. 6, the application of the memory shift in the memory shift mode is performed when the sub shift position is changed and is different from the original by the detection determination process (S1) of the original sub shift position, or When the original sub-shift position sensor signal is detected again and a predetermined application condition is satisfied, that is, on the condition that the main clutch 40 is being operated (S2), shift control is performed by the shift command based on the memory shift (S3). , S4). The clutch operation is detected by the clutch pedal depression switch 22s.

  When the previous sub-shift position sensor signal is detected again by the shift process, the longest use of the memory shift is applied only when the predetermined application condition is met, that is, when the clutch is being operated. Switching to the main shift position is controlled to shift the tractor. For example, when the sub-shift position is “high speed” and the operator is not operating the clutch while the tractor is traveling, the main shift position remains unchanged even if the sub-shift position sensor signal changes from “neutral” to “high speed” again. Thus, shift control due to inappropriate memory shift is avoided.

  Therefore, when the tractor is running, if the sub-shift lever is operated in parallel with the clutch operation, the memory shift is applied in accordance with the operator's intention to control switching to the longest used main shift position. If the above-mentioned application condition is not satisfied even if the sub-shift position sensor signal is received, the main shift position is maintained as it is without applying the memory shift, so that the sub-shift position is reliably reflected while reflecting the operator's intention. The tractor can be operated efficiently and stably by avoiding inappropriate shift control due to erroneous transmission of sensor signals.

  Next, another processing example will be described. As shown in the flowchart of FIG. 7, when the original sub-shift position sensor signal is detected again and a predetermined application condition is satisfied, that is, traveling that can ensure traveling safety. The above-mentioned memory shift is applied (S3, S4) on condition that the vehicle speed is within the range corresponding to the stop (S2a). The vehicle speed is detected by the vehicle speed sensor 60.

  When the immediately preceding sub-shift position sensor signal is detected again by the shift process, the longest use of the memory shift is applied only when the vehicle speed is within the range equivalent to a travel stop that is safe as a predetermined application condition. Switching to the main shift position is controlled to shift the tractor. For example, even if the sub-shift position sensor signal changes from “neutral” to “high-speed” while the sub-shift position is “high speed” and the tractor is traveling at a vehicle speed that exceeds the vehicle speed range equivalent to the stoppage of travel, the main shift position remains unchanged. This is maintained and shift control due to inappropriate memory shift is avoided.

  In this way, when the vehicle speed is within a predetermined low speed range, when the vehicle speed is within a predetermined low speed range, memory shift is applied when the immediately preceding sub-shift position sensor signal is detected again, and switching control to the longest used main shift position is performed. On the other hand, if the application condition is not satisfied even if the sub-shift position sensor signal is received again, the main shift position is maintained as it is without applying the memory shift. Therefore, the control device having the above configuration reliably reflects the operator's intention while avoiding an improper sudden shift due to erroneous transmission of the sub-shift position sensor signal during traveling, so that the tractor can be operated efficiently and stably. It becomes possible.

  Further, in the above shift process, by setting a vehicle speed range corresponding to the travel stop for each sub shift position, the application of the memory shift is controlled based on the vehicle speed corresponding to the substantial travel stop corresponding to the vehicle speed zone corresponding to the sub shift position. can do. For example, the sub-shift position is 1 km / h or less at the “high speed” where the maximum vehicle speed is approximately 30 km / h, and similarly, the maximum speed is approximately 0.6 km / h or less at the “medium speed” where the maximum speed is approximately 6 km / h. At “low speed” of 0.8 km / h, the speed is 0.8 km / h or less. In this case, since “low speed” is always within the vehicle speed range corresponding to safe travel stop, the memory shift is substantially always applied.

  Next, an example in which the application conditions of the memory shift are combined will be described. As shown in the flowchart of FIG. 8, as a predetermined application condition, the above-described clutch operation and travel stop equivalent vehicle speed range is combined conditions (S2, S2a). ) To configure the control.

  In the shift control process described above, the memory shift is applied only when the operator operates the clutch within the safe low speed range when the immediately preceding sub shift position sensor signal is detected again. In addition to erroneous transmission of the position sensor signal, it is possible to avoid shift control by memory shift, including clutch operation during high-speed traveling that is inappropriate for shift operation.

  Next, an example in which the application condition is set for each sub-shift position will be described. As shown in the flowchart of FIG. 9, when the previous sub-shift position sensor signal is detected again and the clutch pedal is operated, the sub-shift position is detected. By the shift position determination process (S2b), the memory shift is applied without the vehicle speed determination process (S3, S4) in the case of "low speed", and the vehicle speed determination process (S2a) is performed in the case of "medium speed" and "high speed". Process according to the combined application conditions.

  As a result of the above shift control process, when the sub-shift position is “low speed”, the maximum speed is approximately 1 km / h and the vehicle speed range is safe, so the memory shift is applied without any vehicle speed condition, and “medium speed” and “high speed” By combining these, sudden deceleration during high speed traveling can be avoided.

Next, another example of control processing when the sub-shift position is “high speed” will be described. In the following description, the same members as those described above are denoted by the same reference numerals, and description thereof is omitted.
Specifically, when the sub-shift for the tractor shown in the power transmission system development diagram of FIG. 10 changes from “high speed” to “high speed” after “neutral” again, for example, the vehicle speed change state diagram of FIG. As described above, if the memory shift is applied when the sub-shift shifts to “high-speed” again after “neutral” during traveling at the “high-speed” 8-speed (30 km / h), in the worst case, the vehicle is suddenly decelerated at the first speed. Therefore, in order to avoid such a situation, the control device is configured to shift at a sixth speed (20 km / h) without using a memory shift.

  As shown in the flowchart of FIG. 12, the control processing procedure includes the “neutral” detection process (S11), the “high speed” detection determination process (S12), and the memory shift switch determination process (S12). In S13), when the sub-shift position is changed from “high speed” to “neutral” and then re-set to “high speed”, the shift process is performed to the main shift position according to the vehicle speed at that time (S14 to S16). is there.

  The main shift position determination process (S15) is based on a speed correspondence table created in advance as shown in FIG. That is, if the vehicle speed is 30 km / h when the sub-shift is set, the main shift is controlled at 8th speed, 6km at 20 km / h, 4th speed at 10 km / h, and 2nd speed at 5 km / h or less. In this case, in order to avoid sudden deceleration, there is no problem if a high main shift is taken, but this does not provide a deceleration effect and is dangerous in another sense.

  Due to the above control processing, the sub-shift sensor becomes poorly contacted while driving at the “high-speed” position of the sub-shift, or the contact is determined to be “neutral” once by touching the sub-shift lever even though the operator does not intend to shift. When the sensor is turned on again, the memory shift is adopted, and in the worst case, the trouble of sudden deceleration at the first speed can be avoided, the stable deceleration shift is automatically determined, and the memory shift stability operation Is secured. Further, it can be implemented by program processing, and can be realized at low cost since no additional device is required.

Next, still another example of control processing when the sub-shift position is “high speed” will be described.
When the sub-shift is "high speed", the control process differs depending on whether you want to travel on the road or the field work. If it is a field work, the memory shift is more convenient to use, but the memory shift is used for road driving. Is not only meaningless but also dangerous.

  Therefore, since the shift position used for actual field work is “high 3”, that is, up to “high speed” 3rd speed, the shift speed faster than this is discriminated as traveling on the road and the memory shift is performed. Is disabled. In this case, the gear position immediately before the sub-shift is set to “neutral” is adopted again. If the immediately preceding main shift position is 3rd or less, the memory shift is applied.

  Specifically, in the case where the sub-shift is “high speed” in the memory shift mode, when “high speed” is obtained again after “neutral”, the corresponding main shift position in FIG. As shown in FIG. 5, the memory shift is applied at the third speed or lower, and the immediately preceding main shift position is maintained at the fourth speed or higher.

  As shown in the flowchart of FIG. 15, the memory shift is applied to the memory shift during work when the sub-shift position is “high speed” and the main shift is 3 or less and the work is being performed ( S21 to S23).

When the sub-shift is “high speed” in the memory shift mode, as shown in the flowchart of FIG. 16, the current main shift position is set to M (S31), and the sub-shift position and the memory shift are determined. When the process (S32 to S35) is changed to "high speed" after "neutral", the memory shift is set to the main shift (S37a) if applicable by the determination process (S36) in which the main shift position is 3rd or less. and if unmatched cell Tsu Sorted by being mainly set the gear position M to the main transmission (S37b).

  By the above control process, when the sub-shift position is “high speed”, the memory shift process avoids sudden deceleration such as flying from the 8th speed to the 1st speed. In this case, stable use of the memory shift can be ensured.

Next, the control process in the draft work will be described.
As shown in the side view of the tractor in FIG. 17, the draft working machine P is connected to the rear portion of the tractor T by a top link 35 and left and right lower links 36 and 36, and a draft sensor is installed at the base of the left and right lower links 36 and 36. Is provided. The draft sensor is configured as a load sensing pin by inserting a strain gauge into the lower link pin 36p, as shown in the rear sectional view (a) and the AA sectional view (b) in FIG. is there.

The lower link pin 36p functioning as a load sensing pin receives a pushing load at the time of lift-up and a pulling load in the traction state as shown in the operation diagram of FIG. 19A, and the detection characteristic diagram of FIG. to enter the sensor output shown in the controller C.

In the control process in the draft work, the weight of the work machine P is detected by the draft sensor, and the accelerator gear shift is started from the gear position corresponding to the weight of the heavy work machine as a low main shift position.
That is, as shown in the flowchart of FIG. 20, the load determination output (S41) by the draft sensor is used to shift the accelerator speed from 4th speed (S42a) when heavy, and start from 6th speed (high speed) when light. (S42b)).

  The accelerator shift is a system that shifts from high 4 (“high speed” 4th speed) to high 8 (“high speed” 8th speed), but in a short time when there is no work equipment and no load is applied. Because it is accelerated, shifting to acceleration and decelerating four times is bothersome because both the acceleration and deceleration experience frequent shocks. The draft sensor detects the weight of the work implement, and the higher the weight, the lower the vehicle speed. However, when the vehicle is light, by increasing the vehicle speed stage at the start, smooth acceleration can be secured without an engine stall at an appropriate lower limit of stepping, and an appropriate acceleration feeling corresponding to the weight can be obtained.

It is an overall side view of a tractor. A power transmission system developed view of a tractor of Figure 1. FIG. 6 is a combination diagram of a main shift and an auxiliary shift. It is a control block diagram of a controller. It is an accumulation state figure of a memory count. It is a flowchart of application of a memory shift. It is a flowchart of another example of application processing. It is a flowchart which shows the other example of a shift control process. It is a flowchart which sets different application conditions for every sub-shift position. It is a power transmission system expansion | deployment figure of the tractor of another example. This is a change in the vehicle speed. It is a flowchart about another example of control processing. It is a speed correspondence table. FIG. 6 is a correspondence diagram of main shift positions. It is a flowchart of the memory shift in operation. It is a flowchart about another example of memory shift application control processing. It is a side view of the tractor which connected the draft working machine. It is the back sectional view (a) and its AA line sectional view (b) of a draft sensor. It is an action figure (a) of a lower link pin, and its detection characteristic figure (b). It is a flowchart of a draft work process.

DESCRIPTION OF SYMBOLS 1 Main transmission part 1a 1st main transmission mechanism (main transmission part)
1b Second main transmission mechanism (main transmission unit)
2 Sub-transmission section 5 Shift control on / off switch (memory shift)
21 Accelerator pedal 21 a Accelerator position sensor 25 Sub-shift lever 25a, 25b, 25c, 25d Sub-shift position sensor 40 Main clutch 51 High speed clutch (second main transmission mechanism)
52 Low speed clutch (second main transmission mechanism)
55 Shift fork (sub transmission)
61 Solenoid (first main speed change mechanism)
62f, 62r solenoid (second main transmission mechanism)
C Shift control unit (controller)
E engine T tractor

Claims (2)

A shift command is issued to the main shift position corresponding to the longest use according to the accumulated use time stored in advance by a sub-shift position sensor signal that detects the switching operation of the sub-shift lever (25) to the shift position, and in accordance with the received shift command. In a tractor shift control device including a shift control unit (C) for switching and controlling the main transmission unit (1),
Application of shift control for switching and controlling the main transmission unit (1) in accordance with the shift command when the previous sub-shift position sensor signal is again detected by the shift control unit (C) is applied to travel from the engine (E). As long as the main clutch (40) for cutting power is being operated ,
A tractor shift control apparatus according to claim 1, wherein a load condition is that a vehicle speed range corresponding to travel stop is set by each of the plurality of shift positions of the sub-shift lever (25) . A shift command is issued to the main shift position corresponding to the longest use according to the accumulated use time stored in advance by a sub-shift position sensor signal that detects the switching operation of the sub-shift lever (25) to the shift position, and in accordance with the received shift command. In a tractor shift control device including a shift control unit (C) for switching and controlling the main transmission unit (1),
Application of the shift control for switching and controlling the main transmission unit (1) in accordance with the shift command when the previous sub shift position sensor signal is detected again by the shift control unit (C) is as follows:
Within the vehicle speed range corresponding to the travel stop set for each of the plurality of shift positions of the sub-shift lever (25) and when the immediately preceding sub-shift position sensor signal is detected again, within the vehicle speed range corresponding to the travel stop. A transmission control device for a tractor characterized by being provided with a certain condition .

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