JPH0820255A - Work vehicle traveling speed change structure - Google Patents

Abstract

(57) [Summary] [Purpose] By arranging multiple hydraulic clutches in parallel,
In the traveling speed change structure of a work vehicle equipped with a hydraulic clutch type speed change device for changing speed by supplying hydraulic oil to one of them and operating it on the transmission side, it is possible to respond before and after speed change during the speed change operation. The operating pressure rise and fall characteristics of the hydraulic clutch are configured to cross each other regardless of the individual difference of each hydraulic clutch. [Structure] A step-up time T1 from when hydraulic oil starts to be supplied to the hydraulic clutch until the operating pressure of the hydraulic clutch reaches a predetermined pressure P4 on the transmission state side is measured for each hydraulic clutch, and a hydraulic pressure corresponding to a gear shift command is measured. After the hydraulic oil starts to be supplied to the clutch (solid line A1 and time point B1), the boosting time T1
A little before the time elapses, the hydraulic oil is discharged from the hydraulic clutch operated on the transmission side (one-dot chain line A3 and time point B2).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission for traveling, in which a plurality of multi-plate hydraulic clutches are arranged in parallel, and hydraulic oil is supplied to one of the plurality of hydraulic clutches for transmission. The present invention relates to a traveling speed change structure for a work vehicle configured to be a hydraulic clutch that is operated to change gears.

[0002]

2. Description of the Related Art An example of a traveling speed change structure for a work vehicle as described above is disclosed in Japanese Patent Application Laid-Open No. 60-69354. In this structure, by devising a port of a control valve for supplying / discharging hydraulic oil to / from each hydraulic clutch of the transmission (see FIG. 3 (A) and (B) of the publication, for example, a shift position of the first speed From 1 to the 2nd speed shift position, 1
As soon as the hydraulic oil is discharged from the high speed hydraulic clutch, 2
It is configured so that the hydraulic oil starts to be supplied to the high speed hydraulic clutch.

As a result, as shown in FIG. 4 of the publication, the lowering characteristic of the working pressure of the first speed hydraulic clutch (P1 in FIG. 4 of the publication) and the working pressure of the second speed hydraulic clutch are shown. The rising characteristic (P2 in FIG. 4 of the above publication) is crossed to prevent a situation in which the transmission of power to the lower hand is momentarily interrupted during a gear shift operation, resulting in a decrease in the speed of the aircraft. .

[0004]

SUMMARY OF THE INVENTION In the structure of the above publication,
When the rise and fall characteristics of the operating pressure are crossed during the gear shift operation, a delicate positional relationship is set for the control valve ports, so high precision is required for machining the control valve. Actually, the precision of processing may vary. Therefore, if the machining accuracy of the control valve varies in this way, the rising operation of the hydraulic oil may be delayed or too early, and the rising and falling characteristics of the working pressure may not intersect well. . The present invention relates to a traveling speed change structure of a work vehicle provided with a hydraulic clutch type speed change device for traveling, irrespective of an error in mechanical processing, individual difference of each part, etc.
It is an object of the present invention to obtain a configuration in which the rising and falling characteristics of the operating pressure can be crossed well during the shift operation.

[0005]

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. In other words, the traveling transmission is operated by arranging a plurality of multi-plate hydraulic clutches in parallel, supplying hydraulic oil to one of the plurality of hydraulic clutches, and operating it on the transmission side. The hydraulic clutch type is provided with an electromagnetically operated valve for supplying and discharging hydraulic oil to and from each hydraulic clutch of the transmission, and a shift operation tool for issuing a shift command for the transmission based on an artificial operation. A first control means for transmitting a first operation signal for operating a hydraulic oil supply side to an electromagnetically-operated valve corresponding to the gearshift command based on a gearshift command from the gearshift operation tool; And a second control means for transmitting a second operation signal to operate on the oil drain side, and the operating pressure of the hydraulic clutch of the transmission is the predetermined pressure on the transmission side. Pressure sensor to detect whether or not For each hydraulic clutch, measure the pressure rising time from when the first operation signal is sent to one solenoid operated valve until the working pressure of the hydraulic clutch corresponding to this solenoid operated valve reaches a predetermined pressure on the transmission state side. A measuring means, and based on a shift command from the shift operating tool, a first operation signal is transmitted from the first control means,
A third control means for operating the second control means is provided so that the second operation signal is transmitted from the second control means shortly before the measured boosting time elapses.

[0006]

With the construction of the present invention, for example, as shown in FIG. 7, the first operation signal is transmitted to the electromagnetically operated valve corresponding to the gearshift command based on the gearshift command from the gearshift operation tool, and this electromagnetic operation is performed. The valve operates on the hydraulic oil supply side, and the operating pressure of the hydraulic clutch corresponding thereto rises to operate on the transmission side (see the solid line A1 in FIG. 7). At the same time, a second operation signal is transmitted to the electromagnetically operated valve that has been operating on the hydraulic oil supply side before the transmission of the shift command, and this electromagnetically operated valve operates on the oil drain side, and the corresponding hydraulic pressure is transmitted. The operating pressure of the clutch decreases and the clutch is operated to the transmission cutoff side (see the chain line A3 in FIG. 7).
As a result, the characteristic of decreasing the operating pressure of the hydraulic clutch that has been operated to the transmission side before the transmission of the gearshift command and the characteristic of increasing the operating pressure of the hydraulic clutch corresponding to the gearshift command intersect.

In the present invention, as shown by the solid line A1 in FIG.
When the first operation signal is sent to the electromagnetically operated valve of the hydraulic clutch corresponding to the shift command (time point B1), from this time point B1,
The pressure increasing time T1 is measured until a time point B5 when the hydraulic clutch operating pressure reaches a predetermined pressure P4 on the power transmission side (a state in which there is an output from the hydraulic clutch pressure sensor). in this case,
In a multi-plate hydraulic clutch, generally, as shown by the solid line A1 in FIG. 7, when the hydraulic oil starts to be supplied, the operating pressure first rises abruptly and then drops a little to stabilize in this state for a short time.
After that, there is a thing which is raised to a linear function or a quadratic function and is operated to the transmission side. On the other hand, when the second operation signal is transmitted to the electromagnetically operated valve and the electromagnetically operated valve is operated to the oil drain side while the hydraulic clutch is being operated to the power transmission side, the hydraulic clutch is transmitted almost simultaneously with the transmission of the second operation signal. The operating pressure of is drastically decreased (see the alternate long and short dash line A3 in FIG. 7 and time B2).

Therefore, if the pressure increasing time T1 of the hydraulic clutch is measured as described above, when the first operation command is transmitted to the electromagnetically operated valve (hydraulic clutch) corresponding to the shift command, the pressure increasing time T1 starts from this time B1. The second operation signal is transmitted to the electromagnetically-operated valve (hydraulic clutch) that is operating on the hydraulic oil supply side before the transmission of the shift command, shortly after the passage of. As a result, the operating pressure rise characteristic of the hydraulic clutch corresponding to the shift command (from time point B2 to time point B3 on the solid line A1 in FIG. 7),
Lowering characteristics of the operating pressure of the hydraulic clutch that has been operated to the transmission side before the transmission of the speed change command (at the time point B of the alternate long and short dash line A3 in FIG. 7).
2 to B3) are crossed. If the pressure rise time of each hydraulic clutch of the transmission for traveling is measured as described above, there are mechanical processing errors and individual differences in each hydraulic clutch and each solenoid operated valve. Regardless of the different times, regardless of this, the hydraulic clutch operating pressure increase characteristic corresponding to the gear change command and the hydraulic clutch operating pressure decrease characteristic operated to the transmission side before the transmission of the gear change command are performed. Can be crossed.

[0009]

As described above, in the traveling speed change structure of the working vehicle equipped with the hydraulic clutch type speed change device for traveling, the electromagnetically operated valve is used for the hydraulic clutch, and the operating pressure of each hydraulic clutch is in the transmission state side. By measuring the pressure increase time until the specified pressure is reached, the rise and fall characteristics of the operating pressure can be crossed well in the middle of the gear shifting operation, regardless of mechanical processing errors and individual differences of each hydraulic clutch. It became possible to improve the shifting performance of the work vehicle.

[0010]

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 or the reverse clutch 6, the cylindrical shaft 7, the main transmission 10 (corresponding to a transmission for traveling), the first
It is transmitted to the left and right rear wheels 14 via the sub transmission 11, the second sub transmission 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 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 10 includes four hydraulic multi-plate first speed clutches 21 (corresponding to hydraulic clutches) and second speed clutches 22.
(Corresponding to a hydraulic clutch), a third speed clutch 23 (corresponding to a hydraulic clutch) and a fourth speed clutch 24 (corresponding to a hydraulic clutch) are arranged in parallel and configured to be a hydraulic clutch type capable of shifting to four stages. 4th speed clutches 21-24
By operating one of them to 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 sub-transmission device 11 is also of a hydraulic clutch type in which two hydraulic multi-plate type low speed clutches 26 and high speed clutches 27 are arranged in parallel and is capable of shifting 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 gear shift lever 28 is swingably supported around the horizontal axis of the control section of the machine body and slides the shift member 53 of the second auxiliary transmission 12 (see FIG. 1). 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. The gear shift lever 28 is a pilot seat (not shown) of the control section.
On the right front side, the horizontal axis of the shift lever 28 is inclined in the machine front-rear direction with respect to the machine body left-right 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 is provided on the lateral side of the speed change lever 28 so that the lock pin 56 can be moved in and out, and an operation pin 57 for moving the lock pin 56 in and out is provided at the upper portion of the speed change lever 28. The lock pin 56 is biased by a spring (not shown) so as to project to the fixed position on the right side of the paper (the operation pin 57 is also biased to the projecting side on the left side of the paper), and the fixed guide By engaging the lock pin 56 with the plate 60, the shift lever 28 is moved to the neutral stop position N and the low speed position L.
And at each of the high speed positions H. And the operation pin 5
When 7 is pushed in, the lock pin 56 is retracted to the fixing release position on the left side of the drawing, and the 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 (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. When the 61 and the shift down button 62 are pressed once, one shift up signal (corresponding to a gear shift command) and one shift down signal (corresponding to a gear shift command) are transmitted, and the main and first sub transmission devices 10 in FIG. The shift operation 11 is performed.

As shown in FIG. 2, a 7-segment shift indicator 64 for displaying the shift positions (1st to 8th gears) of the main and first auxiliary transmissions 10 and 11, and the forward and reverse clutches by the forward / backward 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.
It is detected whether or not the working pressure of 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 reaches a predetermined pressure P4 (see FIG. 7) on the transmission side. A pressure sensor 74 for controlling the current main and first auxiliary transmissions 1 is provided by the detection of each pressure sensor 74.
Shift positions 0 and 11 (first to eighth speeds) are detected, and the detected shift positions are displayed on the shift display portion 64 (step S13).

Next, the speed change lever 28 of 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) (the above is equivalent to the first operation signal and the first control means).

At the same time, the solid line A2 in FIG. 7 (time point 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 indicated 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 electromagnetically operated valves 31b to 34b (step S22) (the above is equivalent to the second operation signal and the second 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. 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, in response to the above-described normal shift operation, the electromagnetic operation valves 31b to 34b and the electromagnetic operation valves 31b to 34b, which are scheduled to be shifted (to be supplied with an operating current), in the main transmission 10 and the first auxiliary transmission 11. 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 operated, 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 (4) and (5) more specifically, for example, when shifting from the shift position of the 2nd speed to the shift position of the 3rd speed, an abnormality occurs in the shift position of the 3rd 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 third speed when shifting from the shift position of the fourth speed to the shift position of the third speed, for example, when the shift down button 62 is pressed, the shift display portion 64 displays the fourth 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 clutch 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 engine speed N2 of the engine 1 is detected by the engine speed sensor 72 shown in FIGS. 1 and 2 (step S44), and the engine speed N1 when there is no load and the engine speed N2. 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 is, 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 rotational 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 operation pin 57 is released and returned (OFF) (time B12), the speed change lever 28 is moved to the neutral stop position N by the lock pin 56. 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.

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 operation 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).

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 to the half-clutch state by the opening / closing valve 51. 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.

(9) Next, setting of the time point B2 of the alternate long and short dash line A3 with respect to the time point B1 of the solid line A1 of FIG. 7 will be described. First, the first speed clutch 21 will be described. As shown by the solid line A1 in FIG. 7, when the operating current is sent to the electromagnetically operated valve 31b of the first speed clutch 21 in the stopped state of the machine body (when the shift lever 28 is operated to the neutral stop position N) (time B1 in FIG. 7). ), From this time point B1 to the time point B5 (the state in which there is an output from the pressure sensor 74 of the first speed clutch 21 in FIG. 1) when the operating pressure of the first speed clutch 21 reaches a predetermined pressure P4 on the transmission state side, Measured (above, equivalent to measuring means).

In this case, as shown by the solid line A1 in FIG. 7, when the operation current is sent to the electromagnetically operated valve 31b and the switching valve 31a is operated to the supply side, the operating pressure of the first speed clutch 21 first rises sharply. , It drops a little and stabilizes in this state for a while. This state corresponds to a state in which a piston (not shown) separated from the friction plate (not shown) starts contacting and pressing the friction plate, and the friction plates separated from each other start contacting each other. Then, the operating pressure of the first speed clutch 21 increases in a linear function or a quadratic function, and the operating pressure P in the transmission state is increased.
Reach 1.

On the other hand, when the second speed clutch 22 is in the transmission state, when the operation current to the electromagnetically operated valve 32b of the second speed clutch 22 is cut off and the switching valve 32a is operated to the oil drain side, FIG. As shown by the alternate long and short dash line A3, the operating pressure of the second speed clutch 22 sharply drops substantially at the same time as the point B2 when the operating current is cut off. Not only the second speed clutch 22 but also the 1, 3, 4 clutches 21,
The same occurs at 23 and 24.

As a result, as described above, the first speed clutch 2
When the boosting time T1 of 1 is measured, 1 from the shift position of the 2nd speed
When the shift operation to the high speed shift position is performed, when the shift down button 62 is pressed and the operation current is sent to the electromagnetic operation valve 31b of the first speed clutch 21, a little before the boosting time T1 elapses from this time point B1. The operation current to the electromagnetically operated valve 32b of the second speed clutch 22 is cut off. As a result, the operating pressure increase characteristic of the first speed clutch 21 (time point B2 to time point B3 of the solid line A1 in FIG. 7) and the operating pressure decrease characteristic of the second speed clutch 22 (time point B2 to B3 of the one-dot chain line A3 in FIG. 7). ) And are in a crossing state (the above corresponds to the third control means). As described above, not only the pressure increasing time T1 of the first speed clutch 21 but also the pressure increasing time T1 of the second, third and fourth speed clutches 22, 23, 24 of the main transmission 10 are measured, and the first speed to the eighth speed is changed. Applies to each shift operation at position.

[Other Embodiments] Boosting time T1 in the preceding paragraph (9)
It is assumed that the measurement is performed at the time of shipment from the factory. However, the boosting time T1 of the 1st to 4th clutches 21 to 24 is measured at any time during the shift operation during normal traveling to obtain the boosting time T.
You may comprise so that it may be updated to new boosting time T1 whenever 1 is measured. 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.

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]

10 Transmission 21, 22, 23, 24 Hydraulic clutch of transmission 31b, 32b, 33b, 34b Electromagnetically operated valve 61, 62 Shifting operation tool 74 Pressure sensor P4 Predetermined pressure on transmission side T1 Boosting time

Claims (1)

[Claims] 1. A traveling transmission (10) comprising a plurality of multi-plate hydraulic clutches (21), (22), (23),
(24) are arranged in parallel, and hydraulic fluid is supplied to one of the plurality of hydraulic clutches (21), (22), (23), (24) and operated to the transmission side to shift gears. The hydraulic clutch type to be operated is configured to include the hydraulic clutches (21) and (2) of the transmission (10).
2), (23), (24) solenoid operated valves (31b), (32b), (33b), (34) for supplying and discharging hydraulic oil
b) and the transmission (10) based on an artificial operation
Gear shifting operation tools (61), (62) for issuing gear shifting commands
And a solenoid operated valve (31) corresponding to the shift command based on the shift command from the shift operation tools (61) and (62).
b), (32b), (33b), (34b), a first control means for transmitting a first operation signal to the hydraulic oil supply side, and a hydraulic fluid supply side before the transmission of the shift command. Operated solenoid operated valves (31b), (32b), (33
b) and (34b) are provided with a second control means for transmitting a second operation signal for operating to the oil drain side, and hydraulic clutches (21), (2) of the transmission (10) are provided.
2), (23), (24) pressure sensor (7) for detecting whether the operating pressure has reached a predetermined pressure (P4) on the transmission side.
4) to the hydraulic clutches (21), (22), (2)
3) and (24), the one solenoid operated valve (31b), (32b), (33)
b) and (34b), the electromagnetic control valves (31b), (32b), (33b),
Hydraulic clutches (21), (2) corresponding to (34b)
2), (23), (24) is provided with a measuring means for measuring the pressure rising time (T1) until the operating pressure reaches the predetermined pressure (P4) on the transmission side, and the shift operation tools (61), ( 62), from the second control means to the second control means, shortly before the measured boosting time (T1) elapses after the first control signal is transmitted from the first control means based on the shift command from the second control means. A traveling speed change structure for a work vehicle, comprising: third control means for operating the second control means so that an operation signal is transmitted.