JPH09310756A - Transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of derivability when abnormality occurs to the position detecting mechanism of a gear shift lever, in a transmission for a vehicle to select a gear shift range by the gear shift lever and effect a shift change within a gear shift range by a gear shift switch. SOLUTION: A gear shift control part is provided with a function to detect abnormality of the position detecting switch of a gear shift lever 11, and a function to release the limit of a gear shift range during the occurrence of abnormality. When the output voltage of a position detecting switch is outside a normal range, the output voltage is automatically set to a very low speed range LL. When the engine is started, the limit of the gear shift range is released and the transmission device is shifted from a first speed to a maximum speed through operation of a shift up switch 42 and a shift down switch 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission for a vehicle, and more particularly to a transmission for a vehicle including a main transmission and an auxiliary transmission such as a tractor.

[0002]

2. Description of the Related Art
A vehicle such as a tractor having a main transmission and an auxiliary transmission as a transmission is generally provided with a shift lever for each of the main transmission and the auxiliary transmission, but simplifies the gear shifting operation. For this reason, there is known a system in which a hydraulic transmission mechanism including electromagnetic valves is provided in the main transmission and the sub transmission, and the hydraulic transmission mechanism is electrically sequence-controlled to shift gears.

In this transmission, a shift range suitable for each of various works such as rotary tillage work, plow work, and simple traveling is individually set in the shift controller,
The shift lever is configured to select a shift range, and upshifting or downshifting within the selected shift range is performed by a shift switch provided in a grip portion of the shift lever.

When the main transmission and the sub-transmission are each four-speed transmissions and each combination has a total of 16 speed change ranges, when the traveling position is selected by the speed change lever, for example, from the 12th speed to the highest speed by the speed change switch. It is configured such that gear shifting can be performed in a running range of up to 16 high speeds, and that gear shifting can be performed in an ultra low speed range of 1 to 4 speeds when an ultra low speed position is selected. Therefore, the operation is significantly easier than the manual operation of the shift levers of the main transmission and the sub transmission.

However, when an abnormality such as a disconnection or a short circuit occurs in a switch or a sensor for detecting the position of a shift lever for selecting a shift range, the shift range selection operation is hindered and an abnormal output of the detection switch or the like occurs. When the shift range is automatically changed from a low speed or a medium speed to a high speed traveling position, the speed may suddenly increase, which may cause a dangerous situation.

Therefore, there arises a technical problem to be solved in order to prevent deterioration of workability and ensure safety when an abnormality occurs in the detection switch or sensor.
The present invention aims to solve the above problems.

[0007]

DISCLOSURE OF THE INVENTION The present invention is proposed in order to achieve the above-mentioned object, and an electric / hydraulic speed change mechanism is provided in a main transmission and an auxiliary transmission to provide the electric / hydraulic speed change mechanism. A plurality of types of shift ranges are set in a shift control unit for controlling the shift range, and shift range setting means for selecting an arbitrary shift range from the plurality of types of shift ranges, and shift operating means for operating shift up / down are provided. In a transmission apparatus for a vehicle configured to be able to perform a shift within the selected shift range by the shift operating means, a means for determining an abnormality of the shift range setting means based on an output voltage of the shift range setting means, and an output abnormality A control means for releasing the limitation of the shift range is provided at the time, and when the output is abnormal, the shift operation means can shift from the minimum shift position to the maximum shift position. There is provided both in the transmission.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a four-wheel drive tractor 1, in which a mission case 3 is connected to a rear end portion of a front frame 2, and the power of an engine 4 mounted on the front frame 2 is transmitted to a traveling drive system in the mission case 3. It is distributed to the PTO drive system, and the traveling drive power is further distributed to the rear wheels 5 and the front wheels 6. A steering 8 is arranged at the upper end of the steering column 7 in the front part of the cab, a forward / reverse switching lever 9 is provided on the side surface of the steering column 7, and a speed change lever 11 is provided beside the seat 10. .

The structure of the power transmission mechanism of the four-wheel drive tractor 1 is publicly known, and as shown in FIG.
The forward / reverse switching device 2 is transmitted to the TO forward / reverse switching device 23.
The power via 2 is transmitted through the four-stage main transmission 24 and the four-stage wet hydraulic clutch type auxiliary transmission 25 electrically controlled by the transmission controller to the rear-wheel drive shaft 26 and the front-wheel drive shaft 2
It is divided into seven.

A wet hydraulic clutch type transmission 28 for switching between rear-wheel drive, four-wheel drive and front-wheel double-speed four-wheel drive is interposed between the front-wheel drive shafts 27. Also, PTO
The forward / reverse switching device 23 transmits power to the PTO transmission 29, and the PTO shaft 30 at the rear of the vehicle body is rotationally driven.

FIG. 3 shows a hydraulic circuit of the transmission, in which two hydraulic cylinders, a first / second speed switching hydraulic cylinder A and a third / fourth speed switching hydraulic cylinder B, are respectively connected to electromagnetic switching valves V1 and V1. The main transmission 24 is controlled by expanding and contracting from the neutral position at V2.
Shift.

The auxiliary transmission 25 drives four pistons in the transmission by switching four electromagnetic proportional control valves V3, V4, V5 and V6 respectively connected to the hydraulic ports on both sides of the two wet hydraulic clutch type transmissions. , A high-low two-stage gear clutch is switched to change the speed, and an intermediate-speed oil passage and a high-speed oil passage are provided from the upstream side in the middle of the oil passage connecting the hydraulic power source and the ultra-low speed hydraulic port C _LL. The low speed oil passages are branched, and the electromagnetic proportional control valves V3, V4, V5 and V6 are inserted in the respective oil passages.

Further, pilot operation switching valves V7, V8, V9 are inserted between the branch points of the respective oil passages, and when one electromagnetic proportional control valve is operated, the branch points of the electromagnetic proportional control valves are operated. The downstream oil passage is closed so that two sets of wet hydraulic clutch type transmissions are not connected at the same time,
It is configured to prevent the occurrence of abnormality.

FIG. 4 shows electromagnetic proportional control valves V3, V4, V5.
A control circuit of V6 is shown, in which a switching valve Q is switched by a control valve drive circuit of a speed change controller 31 to supply a pulse current to a solenoid SOL of the solenoid proportional control valve V to drive the solenoid proportional control valve V. And
The voltage generated in the emitter resistance R by the emitter current of the switching transistor Q and the reference voltage output from the reference voltage generation unit 32 are input to the voltage comparator OP, and the comparison result is fed back to the shift controller 31.

The internal resistance value of the solenoid SOL changes depending on the temperature, and as shown in FIG. 5, the resistance value increases and the current value I decreases as the temperature rises. Rise time T until the detected pulse current reaches the reference current value I _REF
Based on the above, a correction calculation of the pulse width required for a predetermined solenoid driving power is performed, and the ON / OFF duty ratio of the switching transistor Q is controlled to control the solenoid driving power to be constant.

The reference current value I _REF is set high within a range not exceeding the current value I _LO of the solenoid at the maximum temperature, whereby the detection time T is extended as much as possible and the detection accuracy and We are trying to improve the resolution.

Further, time T rise current underlying the pulse width correction is immediately before the past few times, and the average of, for example just before two times the rise time T _i-2, T _i-1 and the current rise time T _i By calculating the time Tme and performing the pulse width correction calculation based on the average time Tme, as shown in FIG. 6, even when the pulse noise n is induced in the solenoid SOL, the correction by the influence of the noise n is performed. The error is reduced.

FIG. 7 shows the procedure of pulse duty ratio control. When an electromagnetic proportional control valve operation command is input (step 101), the control valve drive circuit outputs a drive pulse and the timer starts clock counting ( Step 102). The current of the solenoid is the reference current value I
_{When the} rise time T _i reaching _REF is detected (step 103), the arithmetic unit performs the last two rise times (T).
_i-2 , T _i-1 , T _i ) and the average time Tme are calculated (step 104), and the on-time of the output pulse is calculated from the current value obtained from the average time Tme and the required power energy value (step 104). 105).

Then, the calculated on-time is set in the timer (step 106), and the output is turned off when the timer counts up the set value (step 10).
7 → 108). Then, when one duty cycle time has elapsed, the process returns from step 109 to step 101.

Therefore, the ON pulse width is corrected for each duty cycle and the control error correction of the electromagnetic proportional control valve V is executed in real time, and the shift timing of the auxiliary transmission 25 varies due to the temperature of the transmission and the heat generation of the solenoid itself. It is possible to prevent the shock when shifting.

Further, as another embodiment, instead of the method of calculating the average time Tme from the current rise time of the last several times and the current rise time, the lower limit of the rise time T is set.
_{If MIN} is set and the current rise time T _i is shorter than the lower limit rise time T _MIN , it is regarded as the influence of disturbance such as electromagnetic noise, and the on-pulse width is set to a constant set time, or
You may make it control same as the immediately preceding ON pulse width.

FIG. 8 is a table showing combinations of shift positions of the main transmission 24 and the sub transmission 25 at each of the 16 shift positions. Each stage of the sub transmission 25 (ultra-low speed LL, low speed L, medium speed). (Speed M, high speed H), when the main transmission shifts between the first speed and the fourth speed and shifts to a higher speed range or a lower speed range, the auxiliary transmission 25 is shifted up or down and the auxiliary transmission 25 is shifted. The main transmission 24 is downshifted from 4th speed to 1st speed at the same time as the machine 25 is shifted up, and the main transmission 24 is upshifted from 1st speed to 4th speed at the same time as the sub transmission 25 is downshifted to shift 16 speeds. Can be performed continuously.

As shown in FIG. 9, the speed change lever 11 is pivotally attached to the machine body so as to be rotatable back and forth, protrudes upward from the display plate 41 provided on the side of the driver's seat, and is attached to the side surface of the grip portion 11a at the tip. A shift up switch 42 and a shift down switch 43 are provided. The gear shift lever 11 is click-stopped at five positions of the ultra-low speed position LL, the rotary work position L, the plow or scraping work position M, the neutral position N, and the traveling position H, and the gear shift lever 1
The gear shift controller 31 detects the position via a rotary switch (not shown) connected to the rotation center shaft of No. 1. On the display plate 41, 16 LEDs 44 corresponding to each shift speed are arranged, and the shift range of each shift position is displayed in the row of the LEDs 44.

The central axis of rotation of the speed change lever 11 is connected to a potentiometer, and the speed change controller 31
Determines the rotation direction of the speed change lever 11 by increasing or decreasing the output voltage of the potentiometer, and when the speed change lever 11 separates from the current position, starts speed change to the next position, thereby reducing the time lag of the speed change operation as much as possible. It is configured to be shortened.

As shown in FIG. 10, the shift controller 3
1 is a shift up switch 42, a shift down switch 43, and a rotary switch 4 connected to the speed change lever 11.
5, potentiometer 46 and position sensors SEN1, 2, 3, 4 of hydraulic cylinders A, B of main transmission 24
And the signals of the forward switch 47 and the reverse switch 48 of the forward / reverse switching lever 9 are input, and the solenoids SOL1 of the electromagnetic switching valves V1 and V2 of the main transmission 24 are input in accordance with the respective signals.
SOL2, SOL3, SOL4 and solenoids SOL of the solenoid proportional control valves V3, V4, V5, V6 of the auxiliary transmission 25
_H , SOL _M , SOL _L , and SOL _LL are driven.

In the memory of the shift controller 31, the shift positions H, M, L, which are displayed on the display plate 41, are displayed.
The shift range data of LL is stored, and by operating the shift-up switch 42 and the shift-down switch 43, 1 to 4 steps at the ultra-low speed position LL, 5 to 10 steps at the rotary work position L, plow or scraping work. The shift operation can be performed in the range of 8 to 12 for the position M and from 12 to 16 for the traveling position H.

In addition, the shift controller 31 uses the indicator drive circuit 49 to monitor the shift position 50 of the dashboard.
The control status is displayed on. The shift position monitor 50 includes an LED position indicator 51 for displaying the position of the shift lever 11, a target shift position display section 52 for displaying target shift position information based on inputs from the shift up switch 42 and the shift down switch 43, and The present gear shift position display section 53 for displaying the gear shift position information of

For example, if the shift up switch 42 is pressed three times in the 6th speed state, the target gear shift position display section 52 displays 6
From 9 to 9, the display of the current gear shift position display section 53 increases by one gear from 6 every time the transmission shifts up by one gear, and finally reaches the target gear shift position of 9th gear.
Therefore, the shift state can be visually observed, and when the current shift position display portion 53 and the target shift position display portion 52 do not match after shifting, it is possible to recognize that an abnormality has occurred in the transmission.

Further, the shift controller 31 is provided with an abnormality handling function for handling an abnormality in the signal system of the shift lever 11, and this abnormality handling function is shown in FIG.
It will be described according to.

First, when the power is turned on (step 101), the shift controller 31 reads the output state of each sensor and switch (step 102). Here, if the input voltage from the rotary switch 45 is 0 V indicating a disconnection or 5 V indicating a short circuit, it is determined that the gear shift lever 11 is abnormal, but if the voltage is within the normal range, the gear shift range indicated by the voltage is indicated. The data is read, the upper limit value and the lower limit value of the shift range are set, and the shift range is restricted, and the process proceeds from step 103 to step 104. Then, since the shift range is limited, the routine proceeds from step 104 to step 201, and a normal process, that is, a shift process within the set shift range according to the input of the shift up switch 42 and the shift down switch 43, is performed, and the routine returns to step 102. Run.

When the output voltage of the rotary switch 45 is an abnormal voltage such as 0V or 5V which is out of the normal range, the routine proceeds from step 103 to step 105, and the engine is not started immediately after the power is turned on. Advances to step 106 and sets the ultra-low speed range LL. As a result, the tractor is prevented from traveling at high speed against the operator's intention at the start of work, and safety is maintained. Further, the super low speed position indicator LL of the shift position monitor 49 is made to blink to warn of the occurrence of abnormality.

When the engine is started after being set in the ultra-low speed range LL due to the occurrence of an abnormality, the process proceeds from step 105 to step 107, the restriction of the shift range is released, and the 1st to 16th speeds are operated by operating the shift up switch and the shift down switch. Acceleration and deceleration up to the high speed become possible, and the position indicator 51 of the shift range to which the current shift position belongs blinks (step 108 → 109 →
110 or 108 → 111 → 112).

Further, when the cause of the abnormality disappears and the output of the rotary switch 45 returns to the normal range naturally or as a countermeasure such as repair during the above-mentioned abnormality handling processing,
The process proceeds from step 103 to step 104. Then, since the restriction is released, the routine proceeds to step 113, where the shift range indicated by the shift lever 11 is compared with the current shift position.

Here, for example, the speed change lever 11 is in the middle speed position M, and the current speed change position is the middle speed position M.
If it is outside the range of (5th speed to 10th speed), the shift range restriction release state is maintained and the routine proceeds to step 108. Then, when the shift position is within the shift range of the current position of the shift lever 11 by the shift up operation (steps 109 → 110) or shift down operation (steps 111 → 112) by the shift switches 42 and 43, step 113 Then, the process proceeds from step 114 to step 114 to return from the shift range limitation release state to the shift range limitation state. Then, the process proceeds to steps 102 → 103 → 104 → 201, and the shift switch 4 is operated only within the shift range of the position of the shift lever 11.
A normal processing state in which shift ups and downshifts by 2, 43 can be performed is entered.

As described above, when an abnormality occurs in the speed change lever 11, the engine is automatically set to the ultra-low speed range LL to prevent a risk of sudden start,
When an abnormality occurs after starting or during work, the shift lever 1
Gearshift switch 4 regardless of the gearshift range position of 1
With 2,43, it becomes possible to change the shift range.
It does not hinder work.

When the gear shift lever 11 is normal and the gear shift switches 42 and 43 are abnormal, the position of the gear shift lever 11 is switched to shift to the gear shift position which is initially set within the gear shift range of that position. Therefore, the work can be continued by the four-speed shift operation by the shift lever 11. The initial setting shift position of each shift range is not particularly limited and may be set to an intermediate position within each shift range, or the shift position closest to the shift range immediately before the shift operation is automatically selected. The control program may be set as follows.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the technical scope of the present invention, and it goes without saying that the present invention extends to those modifications. is there.

[0038]

As described above, in the transmission of the vehicle of the present invention, when an abnormality occurs in the gear shift range setting means such as the gear shift lever, the limitation of the gear shift range is released, and the gear shift of the gear shift switch or the like is performed. Since the shift can be performed from the lowest shift stage to the highest shift stage by the operating means, work and running are not hindered, and workability can be prevented from deteriorating when an abnormality occurs.

[Brief description of drawings]

FIG. 1 is a side view of a four-wheel drive tractor.

FIG. 2 is a transmission mechanism diagram of a four-wheel drive tractor.

FIG. 3 is a hydraulic circuit diagram of a transmission of a four-wheel drive tractor.

4 is an electric circuit diagram of the electromagnetic proportional control valve of FIG.

FIG. 5 is a graph of temperature / current characteristics of a solenoid of an electromagnetic proportional control valve.

FIG. 6 is a graph showing a drive pulse of a solenoid of an electromagnetic proportional control valve.

FIG. 7 is a flowchart of on-duty control of a drive pulse of an electromagnetic proportional control valve.

FIG. 8 is a table showing a shift order of a main transmission and an auxiliary transmission.

FIG. 9 is a plan view of a gearshift lever mounting portion of a driver's seat.

FIG. 10 is an input / output explanatory diagram of the shift controller.

FIG. 11 is a flowchart for handling an abnormality in the operation lever.

[Explanation of symbols]

 1 Four-wheel drive tractor 9 Forward / reverse switching lever 11 Shift lever 24 Main transmission 25 Sub-transmission 31 Shift controller 42 Shift up switch 43 Shift down switch 45 Rotary switch 46 Potentiometer 50 Shift position monitor 51 Position indicator V1, V2 Electromagnetic switching valve V3, V4, V5, V6 Electromagnetic proportional control valve

Claims (1)

[Claims] 1. A main transmission and an auxiliary transmission are provided with an electric / hydraulic speed change mechanism, and a plurality of kinds of speed change ranges are set in a speed change control section for controlling the electric / hydraulic speed change mechanism. A shift range setting means for selecting an arbitrary shift range from a range and a shift operating means for operating a shift up / down operation are provided, and a shift of a vehicle configured to be able to shift within the selected shift range by the shift operating means. The apparatus is provided with means for judging an abnormality of the shift range setting means based on the output voltage of the shift range setting means, and control means for canceling the limitation of the shift range when the output is abnormal, and the shift operation is performed when the output is abnormal. A transmission device for a vehicle, characterized in that it is possible to shift from a minimum shift position to a maximum shift position by means.