JPH0820254A - Travel speed change structure of working vehicle - Google Patents

Abstract

PURPOSE:To constitute travel speed change structure in such a way that a hydraulic clutch disposed in series with a speed change gear is easily operated to the transmission side and transmission cutoff side. CONSTITUTION:Lock mechanism 56 is provided to fix a speed change lever 28 for a speed change gear 12 into a neutral stop position N and speed change positions L, H and also to release the fixed state, and the speed change lever 28 is provided with a lock operating means 57 that can changeover-operate the lock mechanism 56 into a fixing position and a fixing release position. When the lock operating means 57 is operated to the fixing release side, a hydraulic clutch disposed in series with the speed change gear 12 is automatically operated to the transmission cutoff side, and when the lock operating means 57 is operated to the fixing side, the hydraulic clutch is automatically operated to the transmission side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear transmission that is operated by sliding a shift member.
The present invention relates to a traveling speed change structure of a work vehicle equipped for traveling.

[0002]

2. Description of the Related Art When a gear transmission as described above is installed, a gear shift lever and a shift member of the gear transmission are mechanically interlocked by a linkage mechanism, and a shift lever is slid to operate a gear shift operation. A general structure is possible.

[0003]

As described above, when the shift member of the gear transmission is constructed so as to be mechanically slid by the gear shift lever, the gear transmission is connected in series with the gear transmission in order to smoothly perform the gear shifting operation. A friction type clutch is arranged in the, and when the shift operation starts, the clutch is operated to the transmission cutoff side,
It is necessary to operate the clutch again to the transmission side at the end of the shift operation. In this case, since it is necessary to operate the clutch to the transmission disengagement side and the transmission side as described above by depressing the clutch pedal different from the gear shift lever, it is necessary to facilitate such clutch operation. There is room for improvement in that point. SUMMARY OF THE INVENTION It is an object of the present invention to provide a traveling gear shift structure for a work vehicle in which a gear shift device for traveling is mechanically gear-shifted by a gear shift lever so that a clutch can be easily operated in response to a gear shift operation. .

[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. That is, [1] a gear shift device for traveling, which is gear-shifted by sliding a shift member, and a hydraulic clutch for traveling power transmission, are arranged in series, and a gear shift lever and a gear transmission device are manually operated. The shift member is mechanically interlocked by the linkage mechanism, the shift member is configured to be slidable by the shift lever, and the shift lever is provided with a lock mechanism that can be fixed and released at each of the neutral stop position and the shift position. A gear shift lever is provided with a lock operation tool that can switch the lock mechanism between a fixed position and a lock release position, and when the lock operation tool is operated to the lock release side, hydraulic oil is discharged from the hydraulic clutch. When the lock operation tool is operated to the fixed side and the lock operation tool is operated to the fixed side, a control means is provided for supplying hydraulic oil to the hydraulic clutch to operate it on the transmission side. It is.

[2] In the constitution of the above item [1], when the lock operation tool is operated to the fixed side, the control means is provided so as to gradually supply the hydraulic oil to the hydraulic clutch and operate the hydraulic oil to the transmission side. Is configured. [3] In the configuration of [2] above, a rotational speed sensor for detecting the rotational speed of the lower transmission system of the hydraulic clutch is provided,
While preventing the rate of increase of the detection value of the rotation speed sensor from exceeding the set value when the lock operation tool is operated to the fixed side,
The control means is configured to gradually supply the hydraulic oil to the hydraulic clutch and operate the hydraulic oil to the transmission side.

[0006]

[Action]

[I] In a gear transmission for a work vehicle, the gear shift lever is operated in a neutral stop position so that the gear shift lever is not inadvertently operated and gear shift operation is not performed, and the gear shift lever does not move due to vibration or the like during traveling. In some cases, a lock mechanism that can be fixed at the shift position is provided. When such a lock mechanism is provided, for example, as shown in FIG. 2, the gear shift lever 28 is provided with a lock operation tool 57 that can switch the lock mechanism 56 between a fixed position and a fixed release position. The lock operation tool 57 can be operated with a closed hand.
As a result, the lock mechanism 56 is locked by the lock operation tool 57.
To the fixed release position to operate the speed change lever 28, and again to operate the lock mechanism 56 to the fixed position by the lock operation tool 57 to fix the speed change lever 28 to the operated position.

In view of the above, when the construction of the above [1] is adopted, as shown in FIGS. 2 and 1, for example, when the lock mechanism 56 is operated to the unlocking position by the lock operation tool 57, it is arranged in series with the gear transmission 12. Hydraulic clutches 5 and 6
It is automatically operated to the transmission cutoff side. As a result, by operating the shift lever 28, the shift member 53 of the gear transmission 12 can be smoothly slid, and the gear shift operation of the gear transmission 12 can be performed. Then, the operation of the shift lever 28 is completed, and the lock mechanism 56 is operated by the lock operation tool 57.
Is operated to the fixed position and the gear shift lever 28 is operated to be fixed to the operated position, the hydraulic clutches 5 and 6 which were operated to the transmission interruption side are automatically operated to the transmission side. As a result, by operating the gear shift lever locking operation tool, the gear shift lever can be fixed and released, and the hydraulic clutch for traveling power transmission can be operated on the transmission side and the transmission cutoff side.

[II] When constituted as in the above item [2],
As in the case of the configuration of the above [1], the "action" described in the above [I] is provided, and in addition to this, the following "action" is provided. According to the constitution [2] above, when the operation of the shift lever is completed and the lock mechanism is operated to the fixed position, the working pressure of the hydraulic clutch operated to the transmission cutoff side is gradually increased. When operated, the hydraulic clutch is operated smoothly on the transmission side with less shock.

[III] When configured as in the preceding paragraph [3], as in the case of the configuration in the preceding paragraph [1] or [2], the "action" described in the preceding paragraph [I] or [II] is provided, In addition to this, it has the following “action”. According to the constitution [3] above, when the operation of the shift lever is completed and the lock mechanism is operated to the lock position, the working pressure of the hydraulic clutch operated to the transmission cutoff side is gradually increased. Operated. In this case, the rate of increase in the rotational speed of the lower side of the hydraulic clutch does not exceed the set value, that is, while suppressing the state in which power is rapidly transmitted by the hydraulic clutch due to fluctuations in the load on the aircraft,
Since the operating pressure of the hydraulic clutch is gradually increased,
The hydraulic clutch operates smoothly on the transmission side with less shock.

[0010]

According to the first aspect of the present invention, in the traveling speed change structure for a working vehicle, wherein the shift member of the gear speed change device is mechanically slid by the speed change lever, the lock operation tool provided on the speed change lever. By operating, the operation of the hydraulic clutch to the transmission side and the transmission cut-off side is automatically performed without the need to operate the clutch pedal separately from the gear shift lever. It was possible to improve the sex. Since the lock lever can be fixed and released at the same time by operating the lock operation tool, the shift operability of the work vehicle can be further improved.

According to the second aspect, as in the case of the first aspect, the above-mentioned "effect of the invention" is provided. According to the second aspect of the invention, the working pressure of the hydraulic clutch that has been operated on the transmission cutoff side is gradually increased, and the hydraulic clutch is operated smoothly on the transmission side with less shock. The gear shifting performance of can be improved.

According to the third aspect of the invention, as in the case of the first or second aspect of the invention, the "effect of the invention" of the first or second aspect of the invention is provided. According to the third aspect of the present invention, the hydraulic clutch is smoothly operated to the transmission side with less shock regardless of the change in the load applied to the machine body, so that the gear shifting performance of the work vehicle can be further improved.

[0013]

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. Power from the engine 1 is used as a forward clutch 5 (corresponding to a hydraulic clutch) or a reverse clutch 6 (corresponding to a hydraulic clutch), a cylindrical shaft 7, a main transmission device 10, a first auxiliary transmission device 11, and a second auxiliary transmission device 1.
2 (corresponding to a gear transmission) and the rear wheel differential device 13 is transmitted to the left and right rear wheels 14. The power branched from immediately before the rear wheel differential device 13 is transmitted to the left and right front wheels 19 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.

The forward clutch 5 and the reverse clutch 6 are 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 device 10 is configured as a hydraulic clutch type in which four hydraulic multi-plate first speed clutches 21, second speed clutches 22, third speed clutches 23, and fourth speed clutches 24 are arranged in parallel, and is capable of shifting in four stages. By operating one of the first speed to fourth speed clutches 21 to 24 on the transmission side, the power from the cylindrical shaft 7 on the engine 1 side is shifted in four steps to the transmission shaft 25 on the lower side. Transmitted.

The first sub-transmission device 11 is also of a hydraulic clutch type in which two hydraulic multi-plate low speed clutches 26 and high speed clutches 27 are arranged in parallel, and the speed can be changed in two stages. , 27 is operated to the transmission side, the power from the transmission shaft 25 on the main transmission 11 side is speed-shifted in two stages and transmitted to the second auxiliary transmission 12 on the lower side. The second sub-transmission device 12 is of a synchromesh type in which the shift member 53 is slid and operated, 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 4th to 4th speed clutches 21-24, and electromagnetic proportional valves 38, 39 for the low speed and high speed clutches 26, 27 of the first auxiliary transmission 11 are connected in parallel. ing.

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 by a spring toward the oil discharge side (transmission cutoff side), 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 the operation parts have electromagnetically operated valves 31b, 32b, 33b, 34b, 36b,
37b, 42b, 44b, 47b, 48b are connected. Each solenoid operated valve 31b-34b, 36b, 37b,
42b, 44b, 47b, and 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 34b.
a, 36a, 37a, 42a, 44a, 47a, 48a
Are supplied to the operation unit of the above, 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 FIGS. 2 and 3, an opening / closing valve 51 capable of discharging pilot hydraulic oil from the operating portions of the switching valves 36a, 37a of the forward and reverse clutches 5, 6 is provided.
1 is biased to the closing side by a spring. A position sensor 6 for detecting the operation position of the clutch pedal 52 is provided with a clutch pedal 52 for mechanically operating the open / close valve 51 to the open side.
8 is provided. At the base of the steering handle 58 for the front wheels 19, a forward / reverse lever 59 for transmitting an electric forward signal and a backward signal is provided. Equipped with an accelerator pedal 69 for artificially changing the accelerator position of the engine 1,
A position sensor 70 for 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 gear shift lever 28 is operated to three positions of the neutral stop position N, the low speed position L (corresponding to the gear shift position) and the high speed position H (corresponding to the gear shift position), and the second auxiliary transmission device 12 is gear-shifted. The speed change lever 28 is arranged on the right front side of a cockpit (not shown) of the control section, and the horizontal axis of the speed change lever 28 is inclined in the machine longitudinal direction with respect to the machine lateral direction. As a result, the speed change lever 28 is swung forward to the right to operate to the low speed position L, and the speed change lever 28 is swung to the left backward (toward the center of the machine body) to operate to the high speed position H. Become.

A lock pin 56 (corresponding to a lock mechanism) that can be operated to move in and out is provided on a lateral side portion of the speed change lever 28, and an operation pin 57 (corresponding to a lock operation tool) for operating the lock pin 56 to change speed. It is provided on the upper portion of the lever 28.
The lock pin 56 is biased by a spring (not shown) so as to project to a fixed position on the right side of the drawing (an operation pin 57.
Is also biased to the protruding side on the left side of the paper), and by engaging the lock pin 56 with the fixed side guide plate 60,
The speed change lever 28 is fixed at each of the neutral stop position N, the low speed position L and the high speed position H. When the operating pin 57 is pushed in, the lock pin 56 is retracted to the fixing release position on the left side of the drawing, 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 position sensor 63 that detects the operation position of the shift lever 28 is provided at the base of the shift lever 28.

A shift-up button 61 and a shift-down button 62 are vertically arranged on the left lateral side surface of the speed change lever 28. When the shift-up button 61 and the shift-down button 62 are pushed once as described later, one shift The shift-up signal and the shift-down signal are transmitted, and the shift operation of the main and first auxiliary transmissions 10 and 11 in FIG. 1 is performed.

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 to detect whether or not the operating pressure of the forward and reverse clutches 5 and 6 has reached a predetermined pressure on the transmission state side. Also, the reverse lamps 65 and 66 are turned on.

(4) Next, the shift operation by the shift up button 61 and the shift down button 62 of the shift lever 28, and the abnormality detection in the shift operation will be described. FIG.
As shown in FIG. 3, first, the forward and reverse clutches 5 and 6 in FIG.
The presence or absence of abnormality is detected in the solenoid proportional valve 35 for use (step S1), and if there is no abnormality, an operating current is sent to the solenoid proportional valve 35 (step S2). Next, the forward / backward lever 59
Is operated to the forward position F (step S3), an operation current is sent to the electromagnetically operated valve 36b of FIG. 3 (step S3).
5), the switching valve 36a is operated to the supply side, the forward clutch 5 is operated to the transmission side, and the forward lamp 65 is turned on (step 6). Conversely, when the forward / reverse lever 59 is operated to the reverse position R (step S3), the solenoid operated valve 3 of FIG.
An operating current is sent to 7b (step S8), and the switching valve 37
2 is operated to the supply side, the reverse clutch 6 is operated to the transmission side, and the reverse lamp 66 is turned on (step S9).
The buzzer 71 operates intermittently (step S10).

In steps S1, S4 and S7 in the above state, the solenoid proportional valve 3 for the forward and reverse clutches 5 and 6
5 and the solenoid operated valves 36b and 37b, when an abnormality such as a short circuit of the operating current is detected, a lower case "c" is displayed and blinks in the lower half segment of the gear shift display section 64 in FIG. 2 (step S11). ), The buzzer 71 operates continuously (step S12). As a result, the operator recognizes that an abnormality has occurred in the operation system of the forward and reverse clutches 5 and 6.

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. Therefore, the main transmission and the first sub-transmissions 10, 11 are used. Eight shifts are possible. In this case, in the state where the low speed clutch 26 of the first auxiliary transmission device 11 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. Therefore, with the high speed clutch 27 of the first auxiliary transmission 11 being operated to the transmission side, the first to fourth speed clutches 21 to 2 of the main transmission 10 are provided.
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 device 11 is provided with a pressure sensor 74 for detecting whether or not the operating pressures thereof reach a predetermined pressure on the transmission state side. Accordingly, the current gear shift positions (1st to 8th gear) of the main and first auxiliary transmissions 10 and 11 are detected by the detection of each pressure sensor 74, and the detected gear shift positions are displayed on the gear shift display section 64. Is performed (step S13).

Next, the speed change lever 28 shown in FIG.
Alternatively, in the state where the shift lever 28 is operated to the high speed position H (step S14), the shift up button 61 of the shift lever 28 is pressed.
Alternatively, the shift down button 62 is pressed once to operate (steps S15 and S16). When the shift-up button 61 is pressed as shown in FIG. 5, it is detected whether or not there is an abnormality in the electromagnetically operated valves 31b to 34b for the main transmission device 10 at the gear shift position one step higher than the current gear shift position. And 4
When shifting from the 5th gear position to the 5th gear position,
The presence / absence of abnormality of the solenoid proportional valve 39 for the high speed clutch 27 in the first auxiliary transmission device 11 is also detected at the same time. On the contrary, when the shift down button 62 is pressed, the presence or absence of abnormality of the electromagnetically operated valves 31b to 34b for the main transmission 10 at the shift position one step lower than the current shift position is detected, and the fifth speed is set. During a gear shift operation from the gear shift position to the fourth gear shift position, the low speed clutch 26 in the first auxiliary transmission device 11 is operated.
The presence / absence of abnormality of the solenoid proportional valve 38 for use is also detected at the same time (step S17).

If no abnormality is detected in the above-mentioned state (step S18), as shown in FIG.
In step S19, the predetermined low pressure P3 of the low speed or high speed clutch 26, 27 operated on the transmission side is obtained as described later (step S19). Then, as shown by the solid line A1 (time point B1) in FIG. 7, when the shift-up button 61 is pressed, the electromagnetic operation for the main transmission device 10 at the shift position one step higher than the current shift position. Valve 31b-
When the operation current starts to be supplied to 34b and the shift down button 62 is pressed to the contrary, the main transmission 10 at the shift position which is one speed lower than the current shift position.
The operation current starts to be supplied to the electromagnetic operation valves 31b to 34b for use (step S20).

At the same time, the solid line A2 in FIG. 7 (time B1)
As shown in, the electromagnetic proportional valves 38, 39 of the low speed or high speed clutches 26, 27 operated on the transmission side in the first auxiliary transmission 11 cause the low speed or high speed clutches 26, 27 operated on the transmission side. The operating pressure is reduced from the operating pressure P2 in the transmission state to the aforementioned predetermined low pressure P3 (step S21). In this case, from the 4th gear position to 5
During the shift operation to the high speed shift position, the operating pressure of the low speed clutch 26 of the first auxiliary transmission 11 is dropped to zero, and the operating pressure of the high speed clutch 27 is raised from zero to a predetermined low pressure P3. On the contrary, during the shifting operation from the 5th speed shift position to the 4th speed shift position, the high speed clutch 2 of the first auxiliary transmission device 11 is operated.
The operating pressure of 7 is reduced to zero, and the operating pressure of the low speed clutch 26 is increased from zero to a predetermined low pressure P3.

Then, as shown by the solid line A1 (time B2 to time B3) in FIG. 7, the operating pressure of the first to fourth speed clutches 21 to 24 on the first speed side or the one speed side in the main transmission 10 is The solenoid operated valves 31b to 34b are operated to raise the operating pressure P1 to the transmission state. At the same time, as indicated by the alternate long and short dash line A3 in FIG. 7 (from time point B2 to time point B3), the first to fourth speed clutches 21 to 24 of the main transmission 10 before the push-up button 61 or the shift-down button 62 are pressed. The operating pressure is lowered from the operating pressure P1 in the transmission state to zero by the solenoid operated valves 31b to 34b (step S22).

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. Alternatively, the operating pressure of the high speed clutches 26 and 27 reaches the operating pressure P2 in the transmission state (step S2
3). In this case, from time B3 to time B on the solid line A2 in FIG.
4, the increasing characteristic of the operating pressure of the low speed or high speed clutch 26, 27 is set for each shift position, and the operating pressure from the time point B3 to the time point B4 is shorter at the shift position on the lower speed side (first speed side). It is time and it is operated soaring.

As described above, the shift-up button 6
Since one shift operation by pressing the 1 or the shift down button 62 is finished, when the shift operation is finished, the shift position after the shift operation is displayed on the shift display section 64 (step S24), and the buzzer 71 is pressed once. And the operator is informed of the end of the gear shifting operation (step S25). 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 step S18 of FIG. 5 for the normal shift operation as described above, the electromagnetic operation valves 31b to 34b, which are scheduled to be shifted (scheduled to supply the operation current) in the main transmission device 10 and the first auxiliary transmission device 11, are electromagnetically operated. When an abnormality such as a short-circuit of the operating current is detected in the proportional valves 38, 39, the gear shift position having the abnormality is displayed on the gear shift display section 64, and this display blinks only for a predetermined time (for example, about 10 seconds). (Step S26). Then, the electromagnetically operated valves 31b to 34b and the electromagnetic proportional valve 3 that have an abnormal gear shift schedule (scheduled to supply an operating current).
The operation current is not supplied to 8, 39, and the shift position before the push operation of the shift up button 61 or the shift down button 62 is left, and the shift position before the push operation is displayed on the shift display portion 64. (Step S27).

(5) When an abnormality is found in step S18 of FIG. 5, if the gear shift lever 28 is being operated to the low speed position L or the high speed position H, the gear shift operation beyond the abnormal gear position cannot be performed. Although it disappears, if the gear shift lever 28 is returned to the neutral stop position N, the gear shift operation beyond the abnormal gear shift position can be performed. Next, this gear shift operation will be described. If an abnormality is found in step S18 of FIG. 5, the worker shifts the gear shift lever 28 as described later.
Is operated from the low speed position L or the high speed position H to the neutral stop position N (step S14 in FIG. 4). As a result, the neutral stop lamp 67 of FIG. 2 is turned on (step S28 of FIG. 6),
If the shift up button 61 or the shift down button 62 is pressed in this state (steps S29, S3)
0), the operation current to the solenoid operated valves 31b to 34b operated on the supply side before the pressing operation is shut off (step S3).
1), the operation current is supplied to the electromagnetic operation valves 31b to 34b that are one speed higher or one speed lower than the current shift position (steps S32 and S33).

In this case, the electromagnetically operated valve 31b after the shifting operation is performed.
If there is no abnormality in ~ 34b, the solenoid operated valves 31b ~ 3
The current gear shift position corresponding to 4b is displayed on the gear shift display portion 64 (steps S34 and S35), and the buzzer 71 operates only once (step S37). On the contrary, if there is an abnormality in the electromagnetically operated valves 31b to 34b after the gear shift operation, the current gear shift position corresponding to the electromagnetically operated valves 31b to 34b is displayed on the gear shift display section 64 and this display blinks (step S3).
4, S36), the buzzer 71 operates only once (step S37).

When the shift up button 61 or the shift down button 62 is further pressed, steps S37 to S14 (see FIG. 4), S28 and S2 are performed.
Returning to 9, the shift operation as described above is performed. As a result, the shift operation can be performed beyond the abnormal shift position.
When the shift lever 28 is operated to the neutral stop position N as described above, the shift operation as described above is continuously performed if the shift up button 61 or the shift down button 62 is continuously pressed. And in this state,
Since the second auxiliary transmission device 12 is operated to the neutral stop position, the first auxiliary device as shown by the solid line A2 in FIG. 7 is used except for the speed change operation between the fourth speed position and the fifth speed position. The transmission 11 side is not operated.

(6) Explaining the states of the above items (4) and (5) more specifically, for example, when shifting from the shift position of the second speed to the shift position of the third speed, an abnormality is found in the shift position of the third speed. If there is, if the shift-up button 61 is pressed, the gear shift display portion 64 changes from the gear shift position display of the second speed to the gear shift position display of the third speed, and the gear shift position display of the third speed blinks. As a result, the operator can recognize that there is an abnormality in the gear shift position of the third speed, the gear shift display unit 64 then returns to the display of the gear shift position of the second gear, and the actual gear shift position is also two.
It remains in the high speed gear position.

On the contrary, if there is an abnormality in the shift position of the 3rd speed when shifting from the shift position of the 4th speed to the shift position of the 3rd speed, for example, when the shift down button 62 is pressed, the shift display portion 64 displays the 4th speed. The display of the shift position of is changed to the display of the shift position of the third speed, and the display of the shift position of the third speed blinks.
As a result, the operator can recognize that there is an abnormality in the gear shift position of the third speed, and the gear shift display unit 64 then returns to the display of the gear shift position of the fourth gear, and the actual gear shift position is also the fourth gear. It remains in the gear position.

Next, in the above-mentioned state, the shift lever 28 is operated from the low speed position L or the high speed position H to the neutral stop position N.
When the shift-up button 61 is pressed in this manner, the gear shift display portion 64 changes from displaying the gear shift position of the second speed to displaying the gear shift position of the third speed, and the display of the gear shift position of the third speed blinks. Further, when the shift-up button 61 is pressed, the shift display portion 64 displays the shift position of the fourth speed, and the actual shift position is also shifted to the shift position of the fourth speed. On the contrary, when the shift down button 62 is pressed, the gear shift display portion 64 changes from the display of the gear shift position of the fourth speed to the display of the gear shift position of the third speed, and the display of the gear shift position of the third speed blinks. Further, when the shift down button 62 is pressed, the gear shift display portion 64 displays the gear shift position of the second gear, and the actual gear shift position is also shifted to the gear shift position of the second gear.

(7) Next, the low speed or high speed clutches 26, 2 of the first auxiliary transmission 11 in step S19 of FIG.
The setting of the predetermined low pressure P3 for 7 will be described. As shown in FIG. 8, the current operation position of the accelerator pedal 69 is detected by the position sensor 70 (step S42), and the no-load of the engine 1 corresponding to the current operation position of the accelerator pedal 69 (accelerator position of the engine 1). Rotational speed N
1 is estimated based on FIG. 9, and this rotation speed N1 is stored and updated (step S43).

Next, the current rotation speed N2 of the engine 1 is detected by the rotation speed sensor 72 shown in FIGS. 1 and 2 (step S44), and the rotation speed N1 under no load and the current rotation speed N2 are detected. The difference N3 is calculated (step S45), and the current shift positions (1st speed to 16th speed) of the main transmission device 10, the first and second auxiliary transmission devices 11 and 12 (shift up button 6).
1 and before pressing the downshift button 62) are detected (step S46). As a result, the rotation speeds N1, N
Based on the difference N3 of 2 and the current shift position (1st speed to 16th speed), the load T applied to the engine 1 is calculated by FIG. 10 (step S47), and based on this load T, step S19 of FIG. And a predetermined low pressure P3 indicated by a solid line A2 in FIG.
Is set (step S48).

In this case, as shown in FIG. 10, the larger the difference N3 between the unloaded engine speed N1 and the current engine speed N2, the larger the load on the engine 1 is judged to be, and the solid line A2 in FIG. The predetermined low pressure P3 is set to a high value (the side close to the operating pressure P2 in the transmission state), and conversely the difference N3 is set.
Is smaller, it is determined that the load on the engine 1 is smaller, and the predetermined low pressure P3 of the solid line A2 in FIG. 7 is set to a lower value (zero side). As shown in FIG. 10, 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. Is set to the operating pressure P2). As described above, the predetermined low pressure P3 is repeatedly set and updated, and step S of FIG.
When it reaches 19, the latest stored predetermined low pressure P3
Is taken in.

When the accelerator pedal 69 is operated, the engine speed of the engine 1 changes with a slight delay. Therefore,
When the accelerator pedal 69 is operated as shown in FIG. 8 (step S41), the rotation speeds N1, N calculated previously are calculated.
The difference N3 from 2 is continuously used as it is (step S49), the current shift position (1st speed to 16th speed) is detected (step S50), the load T applied to the engine 1 is calculated, and the predetermined low pressure is applied. P3 is set (steps S51, 52). After the operation of the accelerator pedal 69, the rate of change of the rotation speed of the engine 1 becomes equal to or lower than the predetermined value D, and when it is determined that the change of the rotation speed of the engine 1 is stable (step S53), steps S41 to S41.
Return to 42.

(8) Next, the shifting operation to the neutral stop position N, the low speed position L and the high speed position H of the speed change lever 28 shown in FIG. 2 will be described. As described in (3) above, the shift pin 28 is moved to the neutral stop position N by the lock pin 56,
It is fixed at either the low speed position L or the high speed position H, and when operating the gear shift lever 28 to another position, it is necessary to push the operation pin 57 of the gear shift lever 28 to release the lock pin 56. There is.

In this case, as shown in FIG. 11, when the speed change lever 28 is operated to the low speed position L, for example,
When the operation pin 57 is pressed (ON) (time point B1)
1), the lock pin 56 is removed from the guide plate 60 and operated. At the same time, an operation signal from the operation pin 57 operates the forward or reverse clutches 5 and 6 to the transmission cutoff side by the electromagnetic operation valves 36b and 37b of FIG. 3, and the electromagnetic proportional valves 38 and 39 cause the first auxiliary transmission device. The 11 low speed or high speed clutches 26 and 27 are operated to the transmission cutoff side. As a result, while the operation pin 57 is being pressed, the speed change lever 28 is pressed.
Is operated from the low speed position L to the neutral stop position N. In this case, as shown in FIG. 1, the first auxiliary transmission device 11 located immediately above the second auxiliary transmission device 12, which is operated to change gears by the transmission lever 28.
However, since the transmission is cut off, the gear shift lever 2
The shift operation to the neutral stop position N by 8 can be easily performed.

After operating the speed change lever 28 to the neutral stop position N, when the operator releases the operating pin 57 and returns it (OFF) (time B12), the lock pin 56 moves the speed change lever 28 to the neutral stop position N. At the same time it is fixed
The forward or reverse clutches 5, 6 are immediately operated to the transmission side by the solenoid operated valves 36b, 37b and the solenoid proportional valve 35 in FIG. 3, and the first auxiliary transmission device 11 is operated by the solenoid proportional valves 38, 39.
The low speed or high speed clutches 26 and 27 are immediately operated to the transmission side (the above corresponds to the control means).

Next, when the operation pin 57 is pushed (ON) (time point B13) while the shift lever 28 is being operated to the neutral stop position N, the lock pin 56 is removed from the guide plate 60 as described above. The forward or reverse clutches 5 and 6 and the low speed or high speed clutches 26 and 27 of the first auxiliary transmission device 11 are operated to the transmission interruption side. As a result, for example, when the speed change lever 28 is operated from the neutral stop position N to the high speed position H while the operation pin 57 is being pressed, the first auxiliary transmission device immediately above the second auxiliary transmission device 12 in the same manner as described above. Since 11 is operated in the transmission cutoff state, the speed change operation to the high speed position H by the speed change lever 28 can be easily performed.

After operating the speed change lever 28 to the high speed position H, when the operator releases the operating pin 57 and returns it (OFF) (time point B14), the lock pin 56 fixes the speed change lever 28 to the high speed position H. At the same time, the solenoid proportional valves 38, 39 immediately operate the low speed or high speed clutches 26, 27 of the first auxiliary transmission 11 to the transmission side. On the other hand, the forward or reverse clutches 5 and 6 are gradually operated to the transmission side as described below. As shown in FIG. 1, a rotation speed sensor 73 for detecting the rotation speed of the cylindrical shaft 7 between the forward and reverse clutches 5, 6 and the main transmission 10.
Is provided at the time point B1 when the operation pin 57 is returned.
4, the operating pressure of the forward or reverse clutches 5 and 6 is increased by the solenoid proportional valve 35 of FIG. 3 so that the rate of increase of the detected value of the rotation speed sensor 73 does not exceed the set value.
The transmission side is operated (time point B15) (the above corresponds to the control means).

It is assumed that the clutch pedal 52 shown in FIGS. 2 and 3 is depressed to operate the forward / reverse clutches 5 and 6 by the opening / closing valve 51 into a half-clutch state. in this case,
As shown in FIG. 1, since the rotation speed sensors 72 and 73 are arranged on the lower side and the upper side of the forward and reverse clutches 5 and 6, respectively, the forward and reverse clutches are different depending on the difference between the detection values of the both rotation speed sensors 72 and 73. The power of the engine 1 absorbed by 5 and 6 is calculated, and when the integrated value of the absorbed power reaches a set value, it is determined that seizure will occur in the forward or reverse clutches 5 and 6, and the buzzer 71 is set at a short interval. It is configured to operate intermittently and notify the operator.

[Other Embodiment] In the above-mentioned embodiment, the forward or reverse clutch 5, 5 is operated by the operation pin 57 of the speed change lever 28.
6 was operated to the transmission side and the transmission cutoff side, but the transmission lever 2
The operation pin 57 of 8 may operate the low speed or high speed clutches 26 and 27 (corresponding to hydraulic clutches) of the first auxiliary transmission 11 to the transmission side and the transmission cutoff side.
Although the shift-up button 61 and the shift-down button 62 are separately provided in the embodiment of FIG. 2, the shift-up signal and the shift-down button 62 are operated by operating one shift switch (not shown) to the shift-up side and the shift-down side. The shift-down signal may be transmitted. The main transmission device 10 and the first auxiliary transmission device 11 in FIG. 1 are configured not as a hydraulic clutch type but as a multi-stage gear shift type similar to the second auxiliary transmission device 12, and a shift member is slid by a hydraulic cylinder. You may comprise so that it may be gear-shifted. In this case, the forward or reverse clutches 5 and 6 are automatically operated to the transmission interruption side by the shift up signal and the shift down signal, and the main transmission device 10 and the first sub transmission device 11 are operated to shift by the hydraulic cylinder. Then, the forward or reverse clutches 5 and 6 may be automatically operated to the transmission side.

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 first half flow of control of gear shift operation and abnormality detection by a shift up button and a shift down button when a shift lever is operated to a low speed position or a high speed position.

FIG. 5 is a diagram showing a second half flow of control of gear shift operation and abnormality detection by the shift up button and the shift down button when the shift lever is operated to the low speed position or the high speed position.

FIG. 6 is a diagram showing a flow of control of gear shift operation and abnormality detection by a shift up button and a shift down button in a state where the shift lever is operated to a neutral stop position.

FIG. 7 is a diagram showing the states of the main and first auxiliary transmission devices during a gear shift operation with a shift up button and a shift down button in a state in which a shift lever is being operated to a low speed position or a high speed position.

8 is a predetermined low pressure (P) on the side of the first auxiliary transmission in FIG.
Diagram showing the flow of setting 3)

9 is a predetermined low pressure (P) on the side of the first auxiliary transmission in FIG.
The figure which shows the relationship between the accelerator position of an engine, and the engine speed at the time of no load of an engine at the time of setting of 3).

10 shows the relationship between the load on the engine and the difference between the engine speed with no load and the current engine speed when the predetermined low pressure (P3) on the side of the first auxiliary transmission in FIG. 7 is set. Figure

FIG. 11 is a diagram showing a state of a forward or reverse clutch and a state of a first auxiliary transmission when a second auxiliary transmission is gear-shifted by a shift lever and an operation pin.

[Explanation of symbols]

 5, 6 Main clutch 12 Gear transmission 28 Gear shift lever 53 Shift member of gear transmission 55 Link mechanism 56 Lock mechanism 57 Lock operation tool 73 Rotation speed sensor N Neutral stop position of shift lever L, H Shift position of shift lever

Claims (3)

[Claims] 1. A gear transmission (1) for traveling, which is operated to shift by slidingly operating a shift member (53).
2) and the hydraulic clutches (5) and 6) for traveling transmission are arranged in series, and the shift lever (28) that is manually operated and the shift member (53) of the gear transmission (12) are connected. Coordination mechanism (5
5) mechanically interlockingly connected to each other, and the shift lever (2
8) the shift member (53) is configured to be slidable, and the shift lever (28) can be locked and unlocked at the neutral stop position (N) and the shift positions (L) and (H). The gear shift lever (28) is provided with a lock operation tool (57) that includes (56) and that can switch the lock mechanism (56) between a fixed position and a release position. ) Is operated to the unlocking side, hydraulic oil is discharged from the hydraulic clutches (5) and (6) and operated to the transmission cutoff side, and the lock operation tool (5)
A traveling speed change structure for a working vehicle, comprising control means for supplying hydraulic oil to the hydraulic clutches (5) and (6) and operating the hydraulic oil on the transmission side when 7) is operated to the fixed side. 2. When the lock operation tool (57) is operated to the fixed side, the hydraulic oil is gradually supplied to the hydraulic clutches (5) and (6) to operate the hydraulic oil to the transmission side. The traveling speed change structure for a work vehicle according to claim 1, wherein the control means is configured. 3. A rotation speed sensor (73) for detecting the rotation speed of a transmission system on the lower side of the hydraulic clutches (5), (6).
When the lock operation tool (57) is operated to the fixed side, the hydraulic clutch (5) is provided so that the rate of increase of the detection value of the rotation speed sensor (73) does not exceed a set value. 3. The traveling speed change structure for a work vehicle according to claim 2, wherein the control means is configured to gradually supply the hydraulic oil to (6) and operate the hydraulic oil on the transmission side.