JPH08338522A - Control method for vehicle power transmission device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for controlling a power transmission device of a vehicle, which prevents sudden start even when a proportional valve fails to open. [Structure] The power of the engine 1 is transmitted to a traveling device D via a hydraulic main clutch A, a hydraulic first transmission B, and a second transmission C, and at the same time, hydraulic oil is supplied to the hydraulic main clutch A. Switching valves 36a and 37a for performing supply / discharge operations,
In a method of controlling a power transmission device of a vehicle, which is connected to a proportional valve 35 for adjusting the pressure of hydraulic oil, the proportional valve 3
5 is determined to be an open failure, and in the case of an open failure, the hydraulic first
When the power transmission of the transmission B is turned off and the second transmission C is on the low speed side L, the hydraulic first
When the first speed change operation of the speed change device B is enabled and the second speed change device C is on the high speed side H, engine power transmission to the traveling device D is disabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a vehicle power transmission device.

[0002]

2. Description of the Related Art The power of an engine is transmitted to a traveling device via a hydraulic main clutch, a hydraulic first transmission and a second transmission, and a hydraulic oil supply / discharge operation is performed on the hydraulic main clutch. A power transmission device for a vehicle is known in which a switching valve for performing the operation and a proportional valve for adjusting the pressure of hydraulic oil are connected.

[0003]

In the above conventional power transmission device, when a stick occurs when the proportional valve is open (hereinafter, such a state is referred to as "open failure"), the main clutch is operated by the switching valve. When the valve is turned on and off, the proportional valve remains open, so that high-pressure hydraulic oil is supplied to the main clutch, causing a sudden connection of the main clutch and a rapid start.

Therefore, an object of the present invention is to provide a control method for a power transmission device of a vehicle, which prevents sudden start even if a proportional valve fails to open.

[0005]

In order to achieve the above object,
The present invention has taken the following technical means. That is, the feature of the present invention is that the power of the engine is transmitted to the traveling device via the hydraulic main clutch, the hydraulic first transmission, and the second transmission, and the hydraulic main clutch is actuated. In the control method of the power transmission device of the vehicle in which the switching valve for supplying and discharging oil and the proportional valve for adjusting the pressure of the hydraulic oil are connected, the open failure of the proportional valve is discriminated. Enables the power transmission of the first hydraulic transmission to be off, and enables the first speed shifting operation of the first hydraulic transmission when the second transmission is on the low speed side. When the second transmission is on the high speed side, the engine power transmission to the traveling device is disabled.

[0006]

According to the present invention, it is determined whether the proportional valve has an open failure. When it is determined that the open failure has occurred, first, the power transmission of the first hydraulic transmission is turned off. And then the second
When the state of the transmission is determined and the second transmission is on the low speed side, the first speed shift operation of the hydraulic first transmission is enabled. That is, since power is transmitted in the lowest speed range, shock due to sudden start is reduced even if the main clutch is suddenly engaged.

When the second transmission is on the high speed side, the transmission of the engine power to the traveling device is disabled, so that the vehicle cannot start.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 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.
The power from the engine 1 is transmitted to the traveling device D via the hydraulic main clutch A, the first hydraulic transmission B, and the second transmission C, and the power from the engine 1 is transmitted to the transmission shaft 2 and the hydraulic multi-plate PTO. It is transmitted to the PTO shaft 4 via the clutch 3.

In the present embodiment, the hydraulic main clutch A is composed of a forward clutch 5 and a reverse clutch 6. The hydraulic first transmission B is composed of a main transmission 10 and a first auxiliary transmission 11. The second transmission is composed of a second auxiliary transmission 12. The traveling device D is a four-wheel drive device that drives the rear wheels 14 and the front wheels 19.

More specifically, the engine 1
The power from the front clutch 5 or the reverse clutch 6, the cylindrical shaft 7, the main transmission device 10, the first auxiliary transmission device 11, the second auxiliary transmission device 12, and the rear wheel differential device 13 are used to drive the left and right rear wheels 14. Be transmitted to. 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 comprises four hydraulic multi-plate type first speed clutches 21, second speed clutches 22 and third speed clutches 23.
And a four-speed clutch 24 are arranged in parallel in a hydraulic clutch type so that four speeds can be obtained. By operating one of the first-fourth clutches 21-24 to the transmission side, The power from the cylindrical shaft 7 on the first side is subjected to a speed change operation in four stages and transmitted to the transmission shaft 25 on the lower side.

The first auxiliary transmission 11 is also of a hydraulic clutch type in which two hydraulic multi-plate type low speed clutches 26 and a high speed clutch 27 are arranged in parallel, and the speed can be changed in two stages. By operating one of 26 and 27 on the transmission side, the transmission shaft 25 on the main transmission 11 side is transmitted.
The power from is transmitted to the second auxiliary transmission device 12 on the lower side by a two-speed shift operation.

The second subtransmission device 12 is of a synchromesh type in which the shift member 53 is slid, and can be shifted in two stages, and is mechanically operated by a shift lever 28 described later. Next, forward and reverse clutch 5,
6. The hydraulic circuit for the main transmission 10 and the like will be described.

As shown in FIG. 3, the oil passage 3 from the pump 29
0, the solenoid proportional valve 35 for the forward and reverse clutches 5, 6 and the pilot operated switching valves 36a, 37a, and the pilot operated switching valves 31a, 32a for the first to fourth speed clutches 21 to 24 of the main transmission 10. , 33a, 3
4a, low speed and high speed clutch 2 of the first auxiliary transmission 11
Electromagnetic proportional valves 38 and 39 for 6 and 27 are connected in parallel.

An oil passage 40 branched from the oil passage 30 is provided with a hydraulic clutch 4 for a diff lock operation in the front wheel diff 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 this 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).

Next, the construction of the operation parts of the forward and reverse clutches 5, 6, the main transmission 10, etc. will be described. As shown in FIGS. 2 and 3, an opening / closing valve 51 capable of draining pilot working oil from the operating portions of the switching valves 36a, 37a of the forward and reverse clutches 5, 6 is provided, and the opening / closing valve 51 is closed by a spring. Biased to the side. A clutch pedal 52 for mechanically operating the open / close valve 51 to the open side is provided, and a position sensor 68 for detecting the operation position of the clutch pedal 52 is provided. At the base of the steering wheel 58 for the front wheels 19, a forward / backward lever 59 for emitting an electric forward signal and a backward signal is provided. The engine 1 includes an accelerator pedal 69 for artificially changing the accelerator position, and a position sensor 70 for detecting the operation position of the accelerator pedal 69.

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 slides the shift member 53 of the second auxiliary speed change device 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.

A lock pin 56 is provided on a lateral side portion 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 an 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 and a shift-down button 62 are vertically arranged on the left lateral side 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 started, and the shift operation of the main and first auxiliary transmissions 10 and 11 in FIG. 1 is performed.

As shown in FIG. 2, the 7-segment shift display portion 64 for displaying the shift positions (1st to 8th speeds) of the main and first auxiliary transmissions 10, 11 and the forward and backward 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.

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. As shown in FIG. 4, the presence or absence of abnormality is first detected in the solenoid proportional valve 35 for the forward and reverse clutches 5 and 6 of FIG. 3 (step S1), and if there is no abnormality, an operating current is sent to the solenoid proportional valve 35. (Step S2).

Next, when the forward / backward lever 59 is operated to the forward position F (step S3), the solenoid operated valve 3 shown in FIG.
An operation current is sent to 6b (step S5), and the switching valve 36
a 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), an operation current is sent to the electromagnetic operation valve 37b of FIG. 3 (step S8), and the switching valve 37a is operated to the supply side. The reverse clutch 6 is operated to the transmission side, the reverse lamp 66 is turned on (step S9), and the buzzer 71 of FIG. 2 is intermittently operated (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, the predetermined low pressure P3 of the low speed or high speed clutches 26, 27 operated on the transmission side is set (step S
19). Then, as shown in actual battle 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 gear shift position one step higher than the current gear shift position. The operating current starts to be supplied to the valves 31b to 34b, and conversely the shift down button 6
When 2 is pressed, the operating current starts to be supplied to the electromagnetically operated valves 31b to 34b for the main transmission device 10 at the speed change position one step lower than the current speed change position (step S20).

At the same time, the solid line A2 in FIG. 7 (time B1)
As shown in FIG. 6, the electromagnetic proportional valves 38, 39 of the low speed and 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 for which the abnormal gear shifting is planned (the operating current is to be supplied).
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). If an abnormality is found in step S18 of FIG.
When 8 is operated to the low speed position L or the high speed position H, the gear shift operation beyond the abnormal gear shift position cannot be performed. However, when the gear shift lever 28 is returned to the neutral stop position N, the abnormal gear shift position is set. It is possible to perform a gear shifting operation beyond the range. Next, this gear shifting operation will be described.

When an abnormality is found in step S18 of FIG. 5, the operator operates the speed change lever 28 from the low speed position L or the high speed position H to the neutral stop position N as will be described later (step S14 of FIG. 4). As a result, the neutral stop lamp 67 in FIG. 2 lights up (step S28 in FIG. 6), and if the shift up button 61 or the shift down button 62 is pressed in this state (steps S29, S30), the power is supplied before the pressing operation. Solenoid operated valve 31b operated to the side
The operation current to 34b is cut off (step S31), and 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 gear 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, 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.

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 above, the speed change lever 28 is fixed by the lock pin 56 at any one of the neutral stop position N, the low speed position L, and the high speed position H.
When operating 8 to another position, it is necessary to push the operation pin 57 of the shift lever 28 to release the lock pin 56.

In this case, as shown in FIG.
8 is operated to the low speed position L, for example, when the operation pin 57 is pushed (ON) (time point B11),
The lock pin 56 is removed from the guide plate 60 and operated. At the same time, the operation signal from the operation pin 57 causes the operation of FIG.
The forward or reverse clutches 5 and 6 are operated to the transmission interruption side by the solenoid operated valves 36b and 37b of the solenoid proportional valves 38 and 3
9, the low speed or high speed clutch 2 of the first auxiliary transmission 11
6, 27 are operated to the transmission cutoff side.

As a result, the speed change lever 28 is moved from the low speed position L to the neutral stop position N while the operation pin 57 is being pressed.
To operate. In this case, as shown in FIG.
Since the first sub-transmission device 11 immediately above the second sub-transmission device 12 which is operated to shift in 8 is operated in the transmission cutoff state, the shift operation to the neutral stop position N by the shift lever 28 is facilitated. You can do it.

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 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 speed change lever 28 is operated to the neutral stop position N, the operation pin 57 is pushed (ON) (time point B13), and the lock pin 56 is disengaged 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, and the operation pin 57 is provided.
From the time point B14 when the return operation is performed, the rotation speed sensor 73
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 does not exceed the set value, and is operated toward the transmission side (time 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. Is operated intermittently to notify the operator.

Now, the control in the case where the solenoid proportional valve 35 "opens" when the forward or reverse clutches 5 and 6 are operated will be described. When the solenoid proportional valve 35 fails to open, the pressure of the hydraulic oil to the forward or reverse clutches 5 and 6 becomes
The pressure is not gradually increased between B14 and B15 shown in FIG. 8 but is rapidly increased and a sudden start occurs. Therefore, the control method of the present invention prevents such a sudden start.

In this control method, as shown in FIG. 9, it is determined whether the solenoid proportional valve 35 is normal or abnormal.
Specifically, this determination is made regardless of whether the command output pressure to the proportional control valve 35 is 3 kg / cm ² or less, the pressure sensor 74 (operating pressure 12 k
When the g / cm ² and the return pressure of 7.5 kg / cm ² ) are in the ON state, it is judged by the control device (see FIG. 2) that there is an “opening failure”.

When it is determined that the open failure occurs, the control device
Switching valves 31a, 32 for the first to fourth speed clutches 21 to 24
a, 33a, 34a and the solenoid proportional valves 38, 3 of the low speed clutch 26 and the high speed clutch 27 of the first auxiliary transmission device 11.
9 and 9 are controlled so that they are all in the cut state. Then, next, the control device determines whether the position of the operation lever 28 of the second auxiliary transmission device 12 is the high speed position H or the low speed position L. In the case of the high speed position H, it is controlled so that the operation for engaging the clutch cannot be performed. In the case of the low speed position L, only the first speed clutch 21 is controlled to be operable. When the 1st speed is selected by operating the shift up button 61 or the shift down button 62, the 1st speed clutch 21 is connected. Then, after that, the main clutch A is connected. After the main clutch A is connected, the shift operation can be performed in the range of 1st speed to 4th speed.

When it is determined that the open failure has occurred, the operator is warned by the speed display and the warning buzzer. The present invention is not limited to the above embodiment.

[0051]

As described above, according to the present invention,
When the proportional valve of the main clutch fails to open, only the first speed can be changed, so that a smooth start is performed.

[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 auxiliary 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 gear shift lever is operated to a neutral stop position.

FIG. 7 is a diagram showing the states of the main and first auxiliary transmissions 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.

FIG. 8 is a forward or reverse clutch when the second auxiliary transmission is gear-shifted by a gear shift lever and an operation pin; and a first clutch.
The figure which shows the state by the side of a subtransmission apparatus.

FIG. 9 is a flowchart showing an example of the present invention.

[Explanation of symbols]

 1 Engine A Hydraulic Main Clutch B Hydraulic First Transmission C Second Transmission D Traveling Device 36a Switching Valve 37a Switching Valve 35 Proportional Valve

Claims (1)

[Claims] 1. The engine power is transmitted to a traveling device via a hydraulic main clutch, a hydraulic first transmission, and a second transmission, and a hydraulic oil supply / discharge operation is performed on the hydraulic main clutch. In a method for controlling a power transmission device of a vehicle in which a switching valve for performing the operation and a proportional valve for adjusting the pressure of hydraulic oil are connected, an open failure of the proportional valve is determined, and in the case of an open failure, the hydraulic first 1 While the power transmission of the transmission is turned off,
When the second speed change device is on the low speed side, the first speed change operation of the hydraulic first speed change device is enabled, and when the second speed change device is on the high speed side, the engine to the traveling device is set. A method of controlling a power transmission device of a vehicle, characterized by disabling power transmission.