JPH08244488A - Traveling shifting structure for work vehicle - Google Patents

Abstract

PURPOSE: To let shifting operation of a transmission be smoothly actuated regardless of a load applied to a vehicle body in the traveling shifting structure for a work vehicle, for which a traveling transmission of a multiplate hydraulic gear shift clutch type is provided. CONSTITUTION: Power from an engine 1 is transmitted to main clutches 5 and 6, a gear shift clutch type transmission 10 and hydraulic clutches 26 and 27, and the shifting operation of transmission 10 is actuated based on a gear shifting command, and simultaneously working pressure for the hydraulic clutches 26 and 27 is lowered to a specified low pressure, and is gradually increased in pressure again so as to be actuated. The greater the difference between the number of revolutions of the engine 1 at present and at the time of no load is, the higher the specified low pressure for the hydraulic clutches 26 and 27 is turned out, and specified low pressure is thereby made higher so as to be set. When an accelerator is abruptly actuated, the number of revolutions of the engine with no load is held down to a low value, and computation is thereby performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling speed change structure for a work vehicle.

[0002]

2. Description of the Related Art In a work vehicle, a transmission for traveling is used.
A plurality of multi-plate hydraulic type speed change clutches are arranged in parallel,
2. Description of the Related Art There is a type in which a shift operation is performed by supplying hydraulic oil to one of a plurality of shift clutches and operating it on the transmission side.

[0003]

As described above, if the shift clutch is provided corresponding to each shift position of the traveling transmission, the shift clutch before the shift command is transmitted when the shift is operated. At the same time as operating to the disengagement side, by gradually increasing the operating pressure of the shift clutch corresponding to the shift command to operate this shift clutch to the transmission side,
Smooth shift operation with less shock can be performed. In a work vehicle having such a transmission for traveling, there is room for improvement in that a smooth gear shift operation with less shock can be performed regardless of the load applied to the machine body. SUMMARY OF THE INVENTION It is an object of the present invention to obtain a structure capable of performing a smooth gear shift operation with less shock, in a gear shift structure of a work vehicle equipped with a gear shift device for traveling with a gear shift clutch.

[0004]

A feature of the present invention resides in that the traveling speed change structure for a work vehicle as described above is configured as follows. [1] The power from the engine is transmitted to the main clutch, the transmission, and the multi-plate hydraulic clutch in this order to perform a speed change operation, and is transmitted to the traveling device on the lower side. A multi-plate hydraulic type shift clutch is arranged in parallel, and a shift operation is performed by supplying hydraulic oil to one of a plurality of shift clutches and operating it on the transmission side. A control valve for supplying and discharging hydraulic oil to and from the speed change clutch, a control valve for supplying hydraulic oil to the hydraulic clutch on the lower side of the transmission and operating this to the transmission side, and a transmission based on artificial operation And a gear shift operation tool for transmitting a gear change command for the transmission, and based on the gear change command from the gear change operation tool, the control valve of the transmission that is operated to the hydraulic oil supply side before the gear change command is issued To control the transmission that corresponds to the shift command. A first control means for operating the valve to the supply side of the hydraulic oil, based on the shift command from the speed change operation member,
Operate the hydraulic clutch control valve on the lower side of the transmission to the hydraulic oil discharge side to reduce the hydraulic clutch operating pressure to a predetermined low pressure, and then move the hydraulic clutch control valve to the hydraulic oil supply side again. A second control means that operates gradually, and a rotation speed sensor that detects the rotation speed of the engine, an accelerator operation tool that artificially changes the accelerator position of the engine, and an accelerator that detects the accelerator position of the engine When the detection value of the sensor and the accelerator sensor begins to change at a rate of change that is higher than the set rate of change, the engine speed at no load corresponding to the detected value of the accelerator sensor is calculated from the rate of change of the detected value of the accelerator sensor. Is calculated as a value of a small change rate, the engine speed without load of the engine calculated by the calculation means, and the current speed detected by the speed sensor. A detection means for detecting a difference between the engine speed and a rotation speed of the engine, and the greater the difference in the rotation speed detected by the detection means, the lower the predetermined low pressure of the hydraulic clutch on the lower side of the transmission that is pressure-reduced by the second control means. Is provided to the high voltage side.

[2] In the configuration of [1] above, when the detected value of the accelerator sensor starts to change at a rate of change larger than the set rate of change, after a set time has elapsed from the start of the change, when the engine is under no load. There is provided delay means for activating the calculation means so as to start the calculation of the rotation speed of the.

[3] In the construction of [1] or [2] in the preceding paragraph, the engine speed under no load corresponding to the detection value of the accelerator sensor is the same as the change rate of the detection value of the accelerator sensor. Equipped with auxiliary calculation means to calculate
When the detected value of the accelerator sensor starts to change at a rate of change equal to or lower than the set rate of change, the engine speed under no load calculated by the auxiliary calculation means and the current engine speed detected by the engine speed sensor To detect the difference between
A restraint means for activating the detection means is provided.

[4] In the construction of [1] or [2] or [3] in the preceding paragraph, the detection of the difference in the number of revolutions by the detecting means, the third
The setting change of the predetermined low pressure by the control means and the depressurizing operation of the hydraulic clutch on the lower side of the transmission based on the predetermined low pressure by the second control means are continuously performed until near the end of the operation by the first control means. Is configured.

[0008]

[Action]

[I] With the configuration as described in [1] above, when a gear shift command is issued from the gear shift operation tool as shown in FIGS. 1 and 5, for example, the control valve of the gear shift clutch operated to the transmission side in the transmission 10. Is operated to the oil drain side, and this speed change clutch is operated to the transmission cutoff side (see the alternate long and short dash line A3 in FIG. 5). At the same time, the control valve of the shift clutch corresponding to the shift command is operated to the hydraulic oil supply side, and the shift clutch is operated to the transmission side (see solid line A1 in FIG. 5). Simultaneously with the shifting operation of the transmission 10 as described above, the control valves of the hydraulic clutches 26, 27 on the lower side are operated toward the oil draining side, and the operating pressures of the hydraulic clutches 26, 27 reach a predetermined low pressure P.
3, the control valves of the hydraulic clutches 26 and 27 are gradually operated to the hydraulic oil supply side (the operating pressure is gradually increased from the predetermined low pressure P3), and the hydraulic clutch 26 is operated. , 27 are operated toward the transmission side (see time point B3 to time point B4 of solid line A2 in FIG. 5).

In this case, as shown in FIG.
Since the hydraulic clutches 26, 27 are arranged closer to the traveling device (wheels, etc.) than those of the main clutches 5, 6,
The power transmitted from the side of the transmission 10 to the hydraulic clutches 26, 27 is the power of low rotation and high torque, rather than the power transmitted from the side to the transmission 10. Therefore,
As shown from the time point B3 to the time point B4 of the solid line A2 in FIG.
When the operating pressure of the hydraulic clutches 26, 27 is gradually increased, even if a small torque fluctuation occurs in the hydraulic clutches 26, 27, the hydraulic clutches 26, 27 easily slip, and a small torque fluctuation causes a transmission shock. It is absorbed properly without appearing as.

[II] When the load on the machine is large,
When the gear shift operation of the transmission and the operation of the hydraulic clutch are performed as described above, when the operation pressure of the hydraulic clutch that has been decompressed to a predetermined low pressure is started to increase, the speed of the machine body is likely to decrease due to the above-mentioned load. . Then, when the operating pressure of the hydraulic clutch is gradually increased in this state, power is transmitted and accelerated in a state where the speed of the machine body is reduced, which may cause a shock.

In the configuration of the above [1], the difference between the engine speed under no load and the current engine speed corresponding to the current detection value of the accelerator sensor is detected. Is regarded as the load on the machine (the difference in the number of revolutions is large, the load on the machine is also large). Thus, in the configuration of the above [1], for example, as shown in FIG. 1 and FIG. 5, the hydraulic clutch 26,
The predetermined low pressure P3 of 27 is set to the high pressure side. Therefore, during the gear shifting operation of the transmission 10, a certain amount of power is transmitted to the traveling device via the hydraulic clutches 26 and 27 on the lower side while the power from the transmission 10 is suppressed, and a decrease in the speed of the machine body is suppressed. If the predetermined low pressure P3 is set to the high pressure side when the operating pressure of the hydraulic clutches 26, 27 is increased from the predetermined low pressure P3, the operating pressure of the hydraulic clutches 26, 27 quickly becomes the operating pressure P2 in the transmission state. Reach

[III] When the accelerator operating tool is operated slowly, the engine speed follows the accelerator operating tool without being delayed, whereas when the accelerator operating tool is operated quickly, the engine rotational speed is increased. Follow up with a delay. As a result, for example, if the gear shift operation is performed when the accelerator operation tool is quickly operated to the high speed side, the engine speed at no load corresponding to the value detected by the accelerator sensor will lag behind the accelerator operation tool. However, the increase in the engine speed is delayed, and the difference (load) in the detected engine speed is judged to be larger than the actual state. . Therefore, the predetermined low pressure set on the basis of the difference (load) in the number of revolutions is set to a value higher than an appropriate value, so that a shock occurs during the gear shift operation.

On the other hand, if the construction is made as in the above item [1], for example, as shown by the solid line in FIG. 9 and the time point C1, the rate of change of the detection value of the accelerator sensor 70 when the accelerator operation tool 69 is quickly operated. Is greater than the set change rate, as indicated by time points C1 and C2 indicated by alternate long and short dash lines in FIG. 9, the change rate is smaller than the change rate of the detected value of the accelerator sensor 70, and the detected value of the accelerator sensor 70 is corresponded. The rotational speed N1 of the engine 1 under no load is calculated. Therefore, for example, even when the shift operation is performed by the shift operation tool when the accelerator operation tool is quickly operated to the high speed side, the engine speed under no load corresponding to the detected value of the accelerator sensor does not follow the accelerator operation tool. It is calculated as a suppressed value. As a result, even if the increase in the engine speed is delayed, the difference in the detected engine speed (the difference between the engine speed at no load and the current engine speed corresponding to the detection value of the accelerator sensor) (load ) Becomes close to the actual state, and the predetermined low pressure set based on the difference (load) in the rotational speed also becomes an appropriate value.

[IV] When constructed as in the above item [2],
As in the case of the configuration of the above item [1], the above item [I] to [II]
I] is provided with the “action”, and in addition to this, the following “action” is provided. When the operator operates the accelerator operation tool to change the accelerator position of the engine,
For a short time after the accelerator operation tool is operated, the same value remains unchanged and the engine speed does not change. After that, the engine speed changes so as to follow the operation of the accelerator operation tool with a delay.

Therefore, when the construction of the above [2] is adopted, for example, when the accelerator operation tool 69 is operated as shown by the solid line in FIG. 9 and the time point C1, from the start time point C1 of the change of the detection value of the accelerator sensor 70. Until the set time T1 has elapsed, the engine speed N1 when the engine 1 is not loaded is not calculated, and based on the engine speed N1 when the engine 1 is not loaded, which was calculated before the accelerator operation tool 69 was operated. , The previous section [I
The predetermined low pressure is set as described in [I]. And
Then, when the set time T1 elapses (time C2), as described in the previous sections [II] and [III], calculation of the engine speed N1 at no load of the engine 1 corresponding to the detection value of the accelerator sensor 70, and the predetermined value. The low pressure setting is performed.

[V] When configured as in the above item [3], as in the case of the above item [1] or [2], the above items [I] to
In addition to the "action" described in [IV], the following "action" is provided. When the accelerator operation tool is quickly operated, the engine speed follows the delay, whereas when the accelerator operation tool is operated slowly, the engine speed follows the accelerator operation tool without being delayed.

With this configuration, with the configuration of the above [3], when the accelerator operation tool is operated slowly (the rate of change of the detected value of the accelerator sensor is less than the set rate of change), the change of the detected value of the accelerator sensor is changed. As the value of the same rate of change as the rate, the engine speed under no load corresponding to the detected value of the accelerator sensor is calculated by following the operation of the accelerator operating tool without delay. As described above, when the accelerator operation tool is operated slowly, the engine speed under no load corresponding to the detection value of the accelerator sensor is not calculated as an unnecessarily suppressed value. , Especially when the accelerator operation tool is operated slowly, the difference in the detected rotation speed (the difference between the engine speed without load and the current engine rotation speed corresponding to the detection value of the accelerator sensor) (load) The value becomes close to the actual state, and the predetermined low pressure set based on the difference (load) in the rotational speed also becomes an appropriate value.

[VI] If constituted as in the above item [4],
As in the case of the configuration of [1] or [2] or [3] above, the "action" described in the above [I] to [V] is provided, and in addition to this, the following "action" is provided. I have it. When configured as in the above item [4], as shown in FIG. 5, for example, as shown in FIG.
When the operating pressures of 6, 27 are set to a predetermined low pressure P3, the preceding paragraph [II] to
The predetermined low pressure P3 is set and updated as described in [V]. As a result, even if the current engine speed changes due to a change in load or the like during the gear shift operation of the transmission, the predetermined low pressure is set and updated accordingly,
The predetermined low pressure is always maintained at an appropriate value during the shifting operation of the transmission.

[0019]

According to the first aspect of the present invention, the hydraulic clutch is arranged on the lower side of the transmission of the type of the transmission clutch, and the hydraulic clutch is gradually operated to the transmission side when shifting the transmission. With this configuration, even small torque fluctuations can be accurately absorbed, and shocks during gear shifting operations can be suppressed to a small extent, thus improving the gear shifting performance of the work vehicle. The load on the machine is detected based on the engine speed, and the degree of decompression of the hydraulic clutch is changed according to the magnitude of this load.Therefore, even when the load is large, gear shifting operation can be performed with less shock, The shifting performance of the vehicle can be further improved. Then, even if a gear shift operation is performed when the accelerator operation tool is quickly operated, by calculating by suppressing the engine speed under no load, the predetermined low pressure of the hydraulic clutch can be obtained regardless of the quick operation of the accelerator operation tool. It was possible to set an appropriate value, and it became possible to suppress the shock at the time of gear shifting operation when the accelerator operation tool was quickly operated, and it was possible to further improve the gear shifting performance of the work vehicle.

According to the second aspect, similar to the case of the first aspect, the above-mentioned "effect of the invention" is provided. According to the second aspect of the present invention, immediately after the accelerator operation tool is quickly operated, the rotational speed of the engine before operation is used without load, so that the predetermined hydraulic clutch can be operated regardless of the quick operation of the accelerator operation tool. It was possible to set the low pressure to a more appropriate value, to further reduce the shock during gear shifting operation when the accelerator operation tool was quickly operated, and to further improve the gear shifting performance of the work vehicle.

According to the third aspect, similar to the case of the first or second aspect, the "effect of the invention" of the first or second aspect is provided. According to the third aspect of the present invention, the predetermined low pressure of the hydraulic clutch can be set to an appropriate value not only when the accelerator operating tool is operated quickly but also when the accelerator operating tool is operated slowly. It was possible to further reduce the shock during the gear shifting operation when the tool was operated slowly, and to further improve the gear shifting performance of the work vehicle.

According to the fourth aspect, similar to the case of the first, second or third aspect, the "effect of the invention" of the first, second or third aspect is provided. According to the fourth aspect of the present invention, the predetermined low pressure of the hydraulic clutch is set and updated even during the gear shifting operation. Therefore, even if the load changes during the gear shifting operation, the predetermined low pressure of the hydraulic clutch can be set to an appropriate value regardless of this. It was possible to maintain it and suppress the shock at the time of gear shifting operation when the load fluctuates, and it was possible to further improve the gear shifting performance of the work vehicle.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 shows the inside of a mission case 8 of a four-wheel drive type agricultural tractor which is an example of a work vehicle.
Is transmitted to the PTO shaft 4 via the transmission shaft 2 and the hydraulic multi-plate PTO clutch 3. The power from the engine 1 is the forward clutch 5 (corresponding to the main clutch) or the reverse clutch 6 (corresponding to the main clutch), the cylindrical shaft 7, the main transmission device 10 (corresponding to the transmission device), the first auxiliary transmission device 11,
It is transmitted to the left and right rear wheels 14 (corresponding to a traveling device) via the second auxiliary transmission device 12 and the rear wheel differential device 13. The power branched from immediately before the rear wheel differential device 13 is transmitted to the left and right front wheels 19 (corresponding to a traveling device) via the transmission shaft 15, the hydraulic clutch type front wheel transmission device 16, the front wheel transmission shaft 17, and the front wheel differential device 18. To be done.

The forward clutch 5 and the reverse clutch 6 are of a hydraulic multi-plate type in which a friction plate (not shown) and a piston (not shown) are combined, and are operated to the transmission side by supplying hydraulic oil. When the forward clutch 5 is operated to the transmission side,
The power of the engine 1 directly flows from the forward clutch 5 to the cylindrical shaft 7, and the vehicle body moves forward. When the reverse clutch 6 is operated to the transmission side, the power of the engine 1 is transmitted to the cylindrical shaft 7 in the reverse rotation state via the reverse clutch 6 and the transmission shaft 20, and the machine body moves backward.

The main transmission 10 comprises four hydraulic multi-disc type first speed clutches 21 (corresponding to speed change clutches) and second speed clutches 2.
2 (corresponding to a speed change clutch), 3rd speed clutch 23 (corresponding to a speed change clutch), and 4th speed clutch 24 (corresponding to a speed change clutch) are arranged in parallel to form a hydraulic clutch type, and the speed can be changed to 4 steps. First speed to fourth speed clutch 21 to
By operating one of the transmission shafts 24 on the transmission side, the power from the cylindrical shaft 7 on the engine 1 side is shifted in four stages and transmitted to the transmission shaft 25 on the lower side.

The first auxiliary transmission 11 is also of a hydraulic clutch type in which two hydraulic multi-plate type low speed clutches 26 (corresponding to hydraulic clutches) and high speed clutch 27 (corresponding to hydraulic clutches) are arranged in parallel. It is possible to shift in two steps,
By operating one of the low speed clutch 26 and the high speed clutch 27 on the transmission side, the power from the transmission shaft 25 on the main transmission 10 side is shifted in two steps, and the second auxiliary transmission 1 on the lower side is operated.
2 is transmitted. The second auxiliary transmission device 12 includes a shift member 53.
It is configured as a synchromesh type for sliding and is capable of shifting in two stages, and is mechanically shifted by a shift lever 28 described later.

(2) Next, the forward and reverse clutches 5, 6,
The hydraulic circuit for the main transmission 10 and the like will be described. FIG.
As shown in FIG. 1, in the oil passage 30 from the pump 29, the electromagnetic proportional valve 35 for the forward and reverse clutches 5, 6 and the pilot operated switching valves 36 a, 37 a, the main transmission device 1 are provided.
Pilot operated switching valves 31a, 32a, 33a, 34a for the fourth to fourth speed clutches 21-24, and electromagnetic proportional valves 38, 39 (corresponding to control valves) for the low speed and high speed clutches 26, 27 of the first auxiliary transmission 11. Are connected in parallel.

An oil passage 40 branched from the oil passage 30 is provided with a hydraulic clutch 4 for differential lock operation in the front wheel differential device 18.
1, a pilot operated switching valve 42a, a hydraulic clutch 43 for differential lock operation in the rear wheel differential device 13
To the pilot operated switching valve 44a, the standard clutch 45 and the speed increasing clutch 46 of the front wheel transmission 16 (see FIG. 1).
(See the reference), pilot operated switching valves 47a, 48
a is connected in parallel. Each switching valve 31a-34
a, 36a, 37a, 42a, 44a, 47a, 48a
Is urged toward the oil discharge side (transmission cutoff side) by a spring, and is operated to the supply side (transmission side) by supplying pilot hydraulic oil as described later.

A pilot oil passage 50 is branched from the oil passage 30 via a pressure reducing valve 49, and the pilot oil passage 50 is connected to the switching valves 31a to 34a, 36a, 37a, 42a, 44a ,.
47a, 48a are connected to the operation parts, and each operation part has an electromagnetic operation valve 31b (corresponding to a control valve), 32b (corresponding to a control valve), 33b (corresponding to a control valve), 34b (corresponding to a control valve). , 36b, 37b, 42b, 44b, 47b, 48
b is connected. Each solenoid operated valve 31b to 34b, 3
6b, 37b, 42b, 44b, 47b, 48b are urged toward the oil discharge side (transmission cutoff side) by springs, and when these are electrically operated to the supply side, the pilot operating oil causes the switching valves 31a to 34a. , 36a, 37a, 42a, 44a,
It is supplied to the operation parts of 47a and 48a, and these are operated to the supply side (transmission side).

(3) Next, the forward and reverse clutches 5,
6. The configuration of the operation unit of the main transmission 10 and the like will be described. As shown in FIG. 2 and FIG. 3, an opening / closing valve 51 capable of draining pilot working oil from the operating portions of the switching valves 36a, 37a of the forward and reverse clutches 5, 6 is provided, and the opening / closing valve 51 is closed by a spring. The clutch pedal 52 is provided for mechanically operating the on-off valve 51 to the open side. Front wheel 19
At the base of the steering handle 58 for vehicle, a forward / reverse lever 59 for transmitting an electric forward signal and a backward signal is provided. It is equipped with an accelerator pedal 69 (corresponding to an accelerator operation tool) for artificially changing the accelerator position of the engine 1.
An accelerator sensor 70 for detecting the accelerator position by detecting the operation position of the accelerator pedal 69 is provided.

As shown in FIG. 2, the speed change lever 28 is swingably supported around the horizontal axis of the control section of the machine body, and the shift member 53 of the second auxiliary speed change device 12 (see FIG. 1) is slid. The shift fork 54 to be operated and the shift lever 28 are mechanically interlocked by a linkage mechanism 55,
The speed change lever 28 is operated to the three positions of the neutral stop position N, the low speed position L and the high speed position H, and the second auxiliary transmission device 12 is operated to change gears. A pair of limit switches 9 for detecting that the speed change lever 28 is operated to the low speed position L and the high speed position H is provided.

A lock pin 56, which is vertically movable, is provided on a lateral side portion of the speed change lever 28, and an operation button 57 for vertically moving the lock pin 56 is provided at an upper portion of the speed change lever 28. The lock pin 56 is urged by a spring (not shown) so as to move to a fixed position above the paper surface (the operation button 57 is also urged to the protruding side on the left side of the paper surface), and the fixed guide Lock pin 56 on plate 60
The gear shift lever 28 is held at each of the neutral stop position N, the low speed position L, and the high speed position H by engaging with.
When the operation button 57 is pushed in, the lock pin 56 is moved to the holding release position below the paper surface, and the gear shift lever 28 can be operated to the neutral stop position N, the low speed position L and the high speed position H.

A shift up button 61 (corresponding to a gear shift operation tool) and a shift down button 62 (corresponding to a gear shift operation tool) are vertically arranged on the left lateral side of the gear shift lever 28,
As will be described later, when the shift-up button 61 and the shift-down button 62 are pressed once, one shift-up signal and one shift-down signal are transmitted, and the shift operation of the main and first auxiliary transmissions 10 and 11 shown in FIG. 1 is performed. Is done.

As shown in FIG. 2, a 7-segment gear shift display portion 64 for displaying the gear shift positions (1st to 8th gears) of the main and first auxiliary transmissions 10, 11 and a forward / reverse clutch by a forward / reverse lever 59. A forward lamp 65 and a backward lamp 66, which indicate which one of 5 and 6 is operated on the transmission side,
A neutral stop lamp 67 indicating that the shift lever 28 is operated to the neutral stop position N is provided in the control section.
As shown in FIG. 3, a pressure sensor 74 is provided for detecting whether or not the operating pressures of the forward and reverse clutches 5 and 6 have reached a predetermined pressure in the transmission state.
The forward and reverse lamps 65 and 66 are turned on by the detection of 4.

(4) Next, the shift operation by the shift up button 61 and the shift down button 62 of the shift lever 28 will be described with reference to FIG. When the forward / backward lever 59 shown in FIG. 2 is operated to the forward position F (step S1), an operation current is supplied to the electromagnetic operation valve 36b shown in FIG. 3 (step S2), and the switching valve 36a is operated to the supply side. Then, the forward clutch 5 is operated to the transmission side, and the forward lamp 65 is turned on (step S3). Conversely, if the forward / reverse lever 59 is operated to the reverse position R (step S
1), an operation current is supplied to the electromagnetic operation valve 37b shown in FIG. 3 (step S4), the switching valve 37a is operated to the supply side, the reverse clutch 6 is operated to the transmission side, and the reverse lamp 66 is operated.
Lights up (step S5), and the buzzer 71 shown in FIG. 2 operates intermittently (step S6).

As shown in FIG. 1, the main transmission 10 is capable of shifting in four stages and the first sub-transmission 11 is capable of shifting in two stages. Gear shifting is possible. In this case, the first auxiliary transmission 1
In the state in which the first low speed clutch 26 is operated to the transmission side, the first to fourth speed clutches 21 to 24 of the main transmission device 10 correspond to the shift positions of the first to fourth speeds, and the first auxiliary transmission device. In the state where the high speed clutch 27 of No. 11 is operated to the transmission side, the first speed to fourth speed clutches 21 to 2 of the main transmission 10 are
4 corresponds to the shift positions of the 5th speed to the 8th speed.

As shown in FIG. 3, the first speed of the main transmission 10 is increased.
Each of the fourth speed clutches 21 to 24 and the low speed and high speed clutches 26 and 27 of the first auxiliary transmission 11 is provided with a pressure sensor 74 for detecting whether or not the operating pressures thereof have reached a predetermined pressure in a transmission state. The current shift positions (1st speed to 8th speed) of the main and first auxiliary transmissions 10 and 11 are detected by the detection of each pressure sensor 74, and the detected shift positions are displayed on the shift display section 64. (Step S7).

In the above state, the shift lever 28 shown in FIG.
It is assumed that the shift-up button 61 or the shift-down button 62 of the shift lever 28 is once pushed while the is operated to the low speed position L or the high speed position H (step S8) (steps S9 and S10). In this case,
As indicated by the solid line A1 (time point B1), when the shift-up button 61 is pressed, the solenoid operated valves 31b to 34b for the main transmission 10 at the shift position one step higher than the current shift position. When the shift down button 62 is pressed, the electromagnetic operation valves 31b to 34b for the main transmission 10 at the shift position one step lower than the current shift position are operated. An operating current is started to be supplied to (step S11) (first
Corresponding to the control means).

At the same time, as indicated by the solid line A2 in FIG. 5 (from time point B1 to time point B2), the low speed or high speed clutch 26 operated on the transmission side in the first auxiliary transmission device 11,
The operating pressure of the low speed or high speed clutches 26, 27 operated on the transmission side is reduced by the solenoid proportional valves 38, 39 of 27 from the operating pressure P2 in the transmission state to a predetermined low pressure P3 (step S12) ( Equivalent to the second control means). The predetermined low pressure P3 is set based on the detection value of the accelerator sensor 70, the rotation speed N2 of the engine 1 and the like, as will be described later in (5), (6) and (7), and the predetermined low pressure P3 is updated. And the setting is continuously performed from the time point B1 to the time point B2. During the shift operation from the 4th speed shift position to the 5th speed shift position, the operating pressure of the low speed clutch 26 of the first auxiliary transmission device 11 is reduced to zero, and the high speed clutch 2
The operating pressure of 7 is increased from zero to a predetermined low pressure P3. On the contrary, during the shift operation from the 5th speed shift position to the 4th speed shift position, the operating pressure of the high speed clutch 27 of the first auxiliary transmission 11 is dropped to zero, and the operating pressure of the low speed clutch 26 is changed from zero to a predetermined low pressure. It is operated to ascend to P3.

Then, as shown by the solid line A1 (time point B2 to time point B3) in FIG. 5, the operating pressures of the first to fourth speed clutches 21 to 24 on the first speed side or the one speed side of the main transmission 10 are increased. The solenoid operated valves 31b to 34b are operated to raise the operating pressure P1 in the transmission state. At the same time, as shown in FIG.
As indicated by the alternate long and short dash line A3 (from the time point B2 to the time point B3), the operating pressure of the first to fourth speed clutches 21 to 24 before the push operation of the shift up button 61 or the shift down button 62 in the main transmission 10 is the electromagnetic pressure. Operation valves 31b-34
The operating pressure P1 in the transmission state is lowered to zero by b (step S13) (corresponding to the first control means).

Next, the first pressure that was maintained at a predetermined low pressure P3
The operating pressure of the low speed or high speed clutches 26, 27 of the auxiliary transmission 11 is gradually increased by the solenoid proportional valves 38, 39 as shown by the solid line A2 (time B3 to time B4) in FIG. The operating pressure of the low speed or high speed clutch 26, 27 reaches the operating pressure P2 in the transmission state (step S14).
(Corresponding to the second control means). In this case, the solid line A shown in FIG.
From time B3 to time B4 of 2, the increase characteristic of the operating pressure of the low speed or high speed clutch 26, 27 is set for each shift position, and the shift position on the low speed side (first speed side) is
The operating pressure from time B3 to time B4 is rapidly increased in a short time.

As described above, the shift up button 6
Since one shift operation by pressing the 1 or shift down button 62 is completed, when the shift operation is completed, the shift position after the shift operation is displayed on the shift display section 64 (step S15), and the buzzer 71 is pressed once. The operator is informed of the end of the gear shifting operation (step S16). The shift operation as described above is not continuously performed even if the shift-up button 61 or the shift-down button 62 is continuously pressed, and the shift-up button 61 or the shift-down button 62 is once returned and then pressed again. Otherwise, the next one shift operation will not be performed.

In the transmission lever 28, the second auxiliary transmission 1
In the case of gear shifting operation of 2, for example, when the gear shift lever 28 is being operated to the low speed position L, if the operation button 57 is pushed and the lock pin 56 is removed downward from the guide plate 60, the electromagnetically operated valve 36b ( Alternatively, the forward clutch 5 (or reverse clutch 6) is automatically provided by the electromagnetically operated valve 37b).
Is operated to the transmission cutoff side.

In this state, the transmission lever 28 is operated to move the second
The shift member 53 of the auxiliary transmission 12 is slid, and after operating the speed change lever 28 to the neutral stop position N or the high speed position H, the operation button 57 is returned to engage the lock pin 56 with the guide plate 60. Then, the solenoid operated valve 3
6b (or the solenoid operated valve 37b) and the solenoid proportional valve 35 automatically and gradually operate the forward clutch 5 (or the reverse clutch 6) to the transmission side.

(5) Next, the low speed or high speed clutches 26, 2 of the first auxiliary transmission 11 in step S12 of FIG.
The setting of the predetermined low pressure P3 for 7 will be described. When the accelerator pedal 69 is held at a certain operation position as shown in FIG. 8 (step S21), when the engine 1 is under no load corresponding to the current detection value of the accelerator sensor 70 (operation position of the accelerator pedal 69). The rotation speed N1 is calculated based on FIG. 6, and this rotation speed N1 is stored and updated (steps S22 and S23) (corresponding to auxiliary calculation means).

Next, the present rotational speed N2 of the engine 1 is shown in FIG.
2 is detected by the rotation speed sensor 72 shown in FIG. 2 (step S24), and a difference N3 between the rotation speed N1 when there is no load and the current rotation speed N2 is detected (step S25) (corresponding to the detection means and the restraining means). ), The current transmission positions of the main transmission 10, the first and second auxiliary transmissions 11 and 12 (from the first speed to
16th speed (before pressing the shift-up button 61 and the shift-down button 62) is detected (step S2).
6). As a result, the load T applied to the engine 1 is calculated from FIG. 7 based on the difference N3 between the rotation speeds N1 and N2 and the current shift position (1st speed to 16th speed) (step S).
27), based on this load T, step S1 shown in FIG.
2 and the predetermined low pressure P3 indicated by the solid line A2 shown in FIG. 5 are set (step S28).

In this case, as shown in FIG. 7, the larger the difference N3 between the unloaded engine speed N1 of the engine 1 and the current engine speed N2, the larger the load on the engine 1 is judged to be. The predetermined low pressure P3 indicated by the solid line A2 is set to a high value (the side close to the operating pressure P2 in the transmission state),
Conversely, the smaller the difference N3 is, the smaller the load on the engine 1 is determined, and the predetermined low pressure P3 of the solid line A2 shown in FIG. 5 is set to a low value (zero side). As shown in FIG. 7, it is determined that the load on the engine 1 increases as the current shift position is on the lower speed side (first speed side), and the predetermined low pressure P3 indicated by the solid line A2 in FIG. Operating pressure P2
Is set to (close to), and the predetermined low pressure P3 is repeatedly set and updated as described above (third side).
Corresponding to the control means).

When the accelerator pedal 69 is operated from the certain operating position to the high speed side and the low speed side (step S21),
If the change rate D (absolute value) of the detection value of the accelerator sensor 70 is not more than the set change rate D3 (steps S29 and S3).
0), the process proceeds to step S22, the engine speed N1 of the engine 1 under no load is calculated (corresponding to auxiliary calculation means), and the difference N between the engine speed N1 under no load of the engine 1 and the current engine speed N2.
3 detection (corresponding to detection means and restraint means) is performed,
The predetermined low pressure P3 is set and updated. As described above, if the change rate D (absolute value) of the detection value of the accelerator sensor 70 is less than or equal to the set change rate D3, the accelerator pedal 6
The engine speed N2 of the engine 1 follows the operation of 9 without delay. Therefore, steps S21, S29, S3
When the cycle of 0 and S22 to S28 is repeated, the engine speed N1 at no load of the engine 1 corresponding to the detection value of the accelerator sensor 70 is calculated as the value of the same change rate D as the detection value of the accelerator sensor 70. And is updated (corresponding to auxiliary calculation means).

(6) Next, setting of the predetermined low pressure P3 when the accelerator pedal 69 is quickly operated from a certain operating position to the high speed side and the low speed side will be described with reference to FIGS. 8 and 9. Like the state up to the time point C1 of the solid line shown in FIG.
It is assumed that the accelerator pedal 69 is held at a certain operation position, and the engine speed N1 of the engine 1 under no load corresponding to the operation position (detection value of the accelerator sensor 70) is calculated. In this state, when the accelerator pedal 69 is operated from a certain operating position (time point C1) (step S21),
The change rate D (absolute value) of the detection value of the accelerator sensor 70 is larger than the set change rate D3 (steps S29 and S3).
0) and the rate of change D is positive (step S31),
It is determined that the accelerator pedal 69 has been quickly operated to the high speed side.

In this case, the first set time T1 (corresponding to the set time) and the first change rate D1 (the absolute value of which is smaller than the absolute value of the change rate D of the detection value of the accelerator sensor 70) (change) Is set (step S3).
2). As a result, the first set time T from the time point C1 when the accelerator pedal 69 is operated as shown by the alternate long and short dash line in FIG.
Until 1 has elapsed, the engine speed N1 at the time of no load of the engine 1 calculated before the operation of the accelerator pedal 69 is used (corresponding to the delay means), and steps S23 to S28 described in the previous section (5). Similarly, the detection of the difference N3 between the unloaded engine speed N1 of the engine 1 and the current engine speed N2 (corresponding to detection means) and the setting of the predetermined low pressure P3 are performed (steps S34 to S35) (steps S34 to S35). Equivalent to 3 control means).

Next, when the first set time T1 has elapsed (time point C2), steps S23 to S28 described in the previous section (5).
Similarly, the rotational speed N1 of the engine 1 under no load is repeatedly calculated based on the first rate of change D1 (corresponding to a calculating means), and the engine is processed in the same manner as steps S23 to S28 described in (5) above. Detection of a difference N3 between the unloaded engine speed N1 of 1 and the current engine speed N2 (corresponding to detection means), and setting of a predetermined low pressure P3 (steps S34 to S3).
5) (corresponding to third control means). Then, when the no-load rotation speed N1 of the engine 1 corresponding to the operation position after the operation of the accelerator pedal 69 is reached (time point C3) (step S3).
6) and returns to step S21.

Next, as shown at time point C4, when the accelerator pedal 69 is operated from a certain operating position (step S4).
21), the change rate D (absolute value) of the detection value of the accelerator sensor 70 is larger than the set change rate D3 (step S29,
S30) and the rate of change D is negative (step S3)
1), it is determined that the accelerator pedal 69 is quickly operated to the low speed side. In this case, the second set time T2 (shorter than the first set time T1) (corresponding to the set time) and the second negative change rate D2 (the absolute value of which is the accelerator sensor 7 described above)
A value smaller than the absolute value of the change rate D of the detected value of 0 and smaller than the first change rate D1 (corresponding to the change rate) is set (step S33).

As a result, as shown by the alternate long and short dash line in FIG. 9, from the time point C4 when the accelerator pedal 69 is operated until the second set time T2 elapses, the engine 1 calculated before the operation of the accelerator pedal 69 is calculated. Speed N1 under no load
Is used (corresponding to the delay means), and similarly to steps S23 to S28 described in the previous section (5), the detection (detection) of the difference N3 between the unloaded engine speed N1 of the engine 1 and the current engine speed N2. (Corresponding to the third control means) and the predetermined low pressure P3 are set (steps S34 to S35).

Next, when the second set time T2 has elapsed (time point C5), steps S23 to S28 described in the previous section (5).
Similarly, the rotational speed N1 of the engine 1 under no load is repeatedly calculated based on the second rate of change D2 (corresponding to a calculating unit), and the engine is processed in the same manner as steps S23 to S28 described in (5) above. Detection of a difference N3 between the unloaded engine speed N1 of 1 and the current engine speed N2 (corresponding to detection means), and setting of a predetermined low pressure P3 (steps S34 to S3).
5) (corresponding to third control means). Then, when the no-load rotation speed N1 of the engine 1 corresponding to the operation position after the operation of the accelerator pedal 69 is reached (time point C6) (step S3)
6) and returns to step S21.

(7) Next, as shown at time points C7 and C8 in FIG. 9, the accelerator pedal 69 is quickly operated to the high speed side,
Based on the first set time T1 and the first rate of change D1, the accelerator pedal 69 is operated in a state in which the engine speed N1 of the engine 1 under no load is calculated and the predetermined low pressure P3 is set.
Is quickly operated to the low speed side again (time point C9).

In this case, the engine speed N1 at no load of the engine 1 calculated by the first rate of change D1 and the operation position of the accelerator pedal 69 (when the engine 1 is at no load corresponding to the operation position of the accelerator pedal 69) Since the engine speed N1) intersects with the engine speed N1, the engine speed N1 at the time of no load of the engine 1 calculated at the time C10 is maintained until the second set time T2 elapses at the time C10 at which the engine speed N1) intersects. The predetermined low pressure P3 is set. When the second set time T2 elapses (time point C11), the engine speed N1 when the engine 1 is not loaded and the predetermined low pressure P3 are set based on the second rate of change D2.

Next, when the accelerator pedal 69 is again quickly operated to the high speed side, the engine speed N1 at no load of the engine 1 calculated by the second rate of change D2 and the operating position of the accelerator pedal 69 (accelerator pedal 69 Therefore, the engine speed N1 of the engine 1 under no load corresponding to the operating position of the engine 1 intersects, and at this time point C12, the engine speed N of the engine 1 under no load calculated at the time point C12.
1 is maintained until the first set time T1 elapses, and the predetermined low pressure P3 is set. Then, when the first set time T1 has elapsed (time point C13), the engine speed N1 when the engine 1 is not loaded and the predetermined low pressure P3 are set based on the first rate of change D1.

[Other Embodiment] In the structure shown in FIG. 1, the low speed clutch 26 and the high speed clutch 27 of the first auxiliary transmission 11 are arranged in parallel on the lower side of the main transmission 10.
Such a first auxiliary transmission device 11 is abolished, and 1 is added to this part.
The present invention may be configured by disposing individual hydraulic clutches.
In the structure shown in FIG. 2, the shift-up button 61 and the shift-down button 62 are separately provided. However, by operating one shift switch (not shown) to the shift-up side and the shift-down side, The shift-down signal may be transmitted.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a transmission system in a mission case.

FIG. 2 is a diagram showing a linked state of a shift lever and a second auxiliary transmission device, a shift display portion, and a linked state of each portion.

FIG. 3 is a hydraulic circuit diagram of a main transmission, a first sub transmission, and the like.

FIG. 4 is a diagram showing a flow of a shift operation by a shift up button and a shift down button of a shift lever.

FIG. 5 is a diagram showing a state of each part at the time of a gear shift operation using a shift up button and a shift down button of a shift lever.

FIG. 6 is a diagram showing a relationship between an operating position of the accelerator pedal in a stopped state and a rotation speed of the engine under no load.

FIG. 7 is a diagram showing the relationship between the load and the difference between the engine speed at no load and the current engine speed.

FIG. 8 is a diagram showing a flow of setting and updating a predetermined low pressure (P3) of the second auxiliary transmission.

FIG. 9 is a diagram showing a relationship between an operation position of an accelerator pedal during operation and a rotational speed of the engine under no load.

[Explanation of reference numerals] 1 engine 5,6 main clutch 10 transmission 14,19 traveling device 21,22,23,24 transmission shift clutch 26,27 hydraulic clutch 31b, 32b, 33b, 34b control valve of main transmission 38, 39 Hydraulic clutch control valve 61, 62 Speed change operation tool 69 Accelerator operation tool 70 Accelerator sensor 72 Rotation speed sensor N1 Engine no-load rotation speed N2 Current engine rotation speed N3 Rotation speed difference D, D1, D2 change rate D3 set change rate T1, T2 set time P3 predetermined low pressure of hydraulic clutch

Claims (4)

[Claims] 1. A power transmission from an engine (1) is transmitted to a main clutch (5), (6), a transmission (10) and a multi-plate hydraulic clutch (26), (27) in this order to perform a gear shift operation. The transmission device (10) is configured to be transmitted to the traveling devices (14) and (19) on the lower side, and the transmission device (10) includes a plurality of multi-plate hydraulic type transmission clutches (21), (22) and (23). ), (24) are arranged in parallel, and the plurality of shift clutches (21), (2
2), (23), (24) is configured to be a model in which hydraulic oil is supplied to one of the transmission clutches and operated to the transmission side to perform a shift operation, and each shift clutch (21) of the transmission (10) is configured. ), (2
2), (23), (24) control valves (31b), (32b), (33b), (34b) for supplying and discharging hydraulic oil
And the hydraulic clutch (2) on the lower side of the transmission (10).
6) Control valves (38) and (39) for supplying hydraulic oil to (27) and operating it to the transmission side, and a gear shift command for the transmission (10) is transmitted based on an artificial operation. Gear shift operating tools (61) and (62) for operating the hydraulic oil supply side before the transmission of the gear shift command based on the gear shift commands from the gear shift operating tools (61) and (62). Control valve (31b) of the transmission (10),
(32b), (33b), (34b) are operated to the oil drain side, and the control valves (31b), (32b), (33b), (34b) of the transmission (10) corresponding to the shift command are actuated. Based on the first control means operated to the oil supply side and the shift command from the shift operation tools (61) and (62), the hydraulic clutches (26) and (27) on the lower side of the transmission (10). ) Control valves (38), (39) to the oil discharge side of the hydraulic oil to cause the hydraulic clutch (26),
The operating pressure of (27) is reduced to a predetermined low pressure (P3), and the control valve (3) of the hydraulic clutches (26) and (27) is reduced.
8) and (39), and second control means for gradually operating again to the hydraulic oil supply side, and a rotation speed sensor (72) for detecting the rotation speed of the engine (1), and the engine (72). 1) An accelerator operation tool (69) for artificially changing the accelerator position, an accelerator sensor (70) for detecting the accelerator position of the engine (1), and a change in the detection value of the accelerator sensor (70). When the rate of change (D) that is greater than the rate (D3) begins to change,
A rate of change (D1) that is smaller than the rate of change (D) of the detected value of the accelerator sensor (70) in the engine speed (N1) corresponding to the detected value of the accelerator sensor (70) under no load. ), (D2) as a value, the engine speed (N1) when the engine (1) is not loaded, the current speed detected by the speed sensor (72). Engine (1) speed (N2)
And a detection means for detecting a difference (N3) between the transmission (10) and the rotation speed difference (N3) detected by the detection means. Lower hydraulic clutch (26),
A traveling speed change structure for a working vehicle, comprising: a third control means for changing the predetermined low pressure (P3) of (27) to a high pressure side. 2. When the detected value of the accelerator sensor (70) starts to change at a rate of change (D) larger than the set rate of change (D3), a set time (T1) from the start of the change,
The traveling of the work vehicle according to claim 1, further comprising delay means for activating the arithmetic means so as to start calculation of the unloaded engine speed (N1) after the lapse of (T2). Gear shifting structure. 3. The engine speed (N1) at no load of the engine (1) corresponding to the detection value of the accelerator sensor (70).
Is provided as an auxiliary calculation means for calculating the value of the same change rate as the change rate (D) of the detected value of the accelerator sensor (70), and the detected value of the accelerator sensor (70) is less than or equal to the set change rate (D3). When the rate of change (D) starts to change, the engine speed (N1) of the engine (1) under no load calculated by the auxiliary computing means and the current engine speed (72) detected by the engine speed sensor (72). The traveling speed change structure for a work vehicle according to claim 1 or 2, further comprising: a check mechanism that operates the detection unit so as to detect a difference (N3) from the rotation speed (N2) of 1). 4. A difference (N3) in the number of rotations by the detecting means.
Detection, the predetermined low pressure (P3) by the third control means
Setting change and depressurizing operation of the hydraulic clutches (26), (27) on the lower side of the transmission (10) based on the predetermined low pressure (P3) by the second control means are operated by the first control means. The traveling speed change structure for a working vehicle according to any one of claims 1 or 2 or 3, wherein the structure is configured to be continuously performed until near the end.