JP3503590B2 - Agricultural work vehicle transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a transmission for an agricultural work vehicle such as a tractor. 2. Description of the Related Art To change the traveling speed of an agricultural work vehicle such as a tractor, an automatic transmission mechanism is incorporated in a transmission to detect a shift operation and a switch operation. Automatic shift control automatically performed by control has been attempted. In such automatic shift control, the frictional connection pressure of the clutch is controlled by controlling the hydraulic pressure by an electromagnetic proportional pressure control valve.
In order to reduce the shock at the beginning of the connection, make a connection while sliding slightly with a small pressure to reduce the shock at the time of connection so that the connection state is comparable to the manual operation feeling of the operator, and to prevent slippage after the connection The pressure is gradually increased. [0003] However, in many cases, conventional boosting curves use two types of curves that are fixed in accordance with the switching between the high speed and the low speed of the auxiliary transmission portion. Since priority is given to the reduction of the shock at the beginning of the clutch connection, there has been a problem that the automatic shifting operation at the time of work or running takes too much time. Therefore, the present invention provides a map in which the frictional connection pressure of the clutch during the shifting operation of the agricultural work vehicle is determined in advance according to each element of the operation state of the agricultural work vehicle at that time.
The information is appropriately selected from the information and automatically controlled so as to obtain an optimum connection state. SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a transmission device for an agricultural work vehicle as follows.
That is, the up / down mechanism provided on the handle of the shift lever 19
Operating the shift switch 20 for
Speed part 6 and the shift lever 19 in the shift passage 21
An auxiliary transmission portion 7 for performing a shift operation by moving in the front-rear direction;
Equipped with a hydraulic switching clutch 3 for switching the direction of movement of the body
When shifting, the main clutch is disengaged after the switching clutch 3 is disengaged.
The main change of the actuator of the speed change section 6 is caused by the operation of 27 and 28.
The speed section 6 is switched to a predetermined position, and after the shift is completed,
Agricultural work vehicle configured so that the switching clutch 3 is connected
The speed of the engine and the speed change of the
It depends on the position of the shaft and the rolling state of the running wheels
The connection pressure pattern of the switching clutch 3 is
Is stored as map information in advance, and based on this map information,
The connection pressure pattern of the switching clutch 3 is selected and changed.
So it was farming vehicles of the transmission device in which. According to the above arrangement, when starting or running on the agricultural work vehicle, the operation of engaging and disengaging the clutch 3 is automatically performed by the speed change operation. In this case
The speed of the engine and the speed change of the
When the shift position and the rolling state of the running wheels are detected, the
The connection pressure pattern of the switching clutch stored in the
The boost control is performed according to the cycle . As described above, a map can be obtained without performing arithmetic processing.
To determine the connection pattern of the switching clutch based on the information
The processing speed is high and the configuration can be simplified . Therefore, prioritizing the reduction of the shock at the beginning of the connection of the clutch 3 as in the prior art does not cause the problem that the automatic shifting operation during work or running takes too much time, and is consistent with the manual operation feeling of the operator. Connection. Embodiments of the present invention will be specifically described below with reference to the drawings. As shown in FIG. 1, a tractor embodying the present invention is provided with a switching clutch 3 for switching between forward and backward movements through an input clutch 5 for transmitting engine power from an input side of the transmission 1 as shown in FIG. 3 through a main transmission section 6 and an auxiliary transmission section 7 of an automatic transmission mechanism using a gear train, and a power transmission connection to a rear wheel differential device 8, and a 4WD device 10 is provided from the auxiliary transmission portion 7 through a front wheel clutch 9. 1
0 to the front wheel drive shaft. This 4WD
The device 10 is a normal four-wheel drive that drives the front wheels and the rear wheels at substantially the same speed.
Switching control is performed between WD drive and front wheel shift 4WD in which the front wheels are driven faster than the rear wheels during turning. On the other hand, the input clutch 5
It is constituted by being operatively connected to a PTO transmission section 12 via an O-clutch 11. The automatic control circuit that controls this tractor
As shown in FIG. 2, a controller 13 is provided at the center, and an input side of the controller 13 includes an engine rotation sensor 14 for detecting an engine rotation speed, a wheel rotation sensor 15 for detecting a wheel rotation speed, and Main shift position sensor 16 for detecting the shift position of section 6 and auxiliary shift position sensor 1 for detecting the shift position of sub-transmission section 7
7, a forward / reverse lever position sensor 18 for detecting an operation position of a forward / reverse switching lever for performing forward / backward switching, and the main transmission unit 6 provided on an auxiliary transmission shift lever 19 for performing a shift operation of the auxiliary transmission unit 7. Main gear shift switch 2 for performing gear shift operation
0 and an auxiliary transmission shift lever sensor 22 provided in the shift passage 21 of the auxiliary transmission shift lever 19 for detecting a shift operation of the auxiliary transmission shift lever 19, and the output of the main transmission unit 6 is A 1-2 speed shift electromagnetic valve 23 and a 3-4 speed shift electromagnetic valve 24 for performing a shift shift, a forward / reverse switching electromagnetic valve 25 for performing forward / reverse switching, and an electromagnetic proportional pressure control valve 2 for increasing hydraulic pressure; When the engine is started, the forward / reverse switching lever is connected to a safety relay 26 for preventing the forward / reverse switching lever from being started when the lever is not in the neutral position. As shown in FIG. 3, the speed change shift structure of the main speed change section 6 includes a 1-2 speed shift solenoid valve 23 for shifting between a first speed and a second speed across a neutral position, and a synchro hydraulic cylinder 27.
And the 3-4 speed shift solenoid valve 24 for shifting the 3rd speed and the 4th speed across the neutral position and the synchro hydraulic cylinder 28 are connected. As shown in FIG. 4, the shift shift configuration of the sub-transmission portion 7 is such that, when the sub-transmission shift lever 19 is operated, the HL speed, the M-speed, and the M-LL speed are shifted, respectively. -Connect each LL-speed shift solenoid valve to a synchro hydraulic cylinder (not shown). As shown in FIG. 3, the switching clutch 3 for switching between forward and reverse is connected to the forward / backward switching electromagnetic valve 25, and the forward / backward switching electromagnetic valve 25 and the electromagnetic proportional pressure control valve 2 are connected to each other. Connect and configure. The connection pressure of the switching clutch 3 is determined based on each element of the operation state of the tractor, that is, the engine rotation speed, the theoretical rotation speed of the wheel calculated from the shift position, and the rolling state of the wheel detected by the wheel rotation sensor 15. For example, as shown in FIG. 5, the vertical axis indicates the pressure intensity and the horizontal axis indicates the elapsed time, as shown in FIG. According to the chart, the minimum shock and the shortest time in the conditions at that time, that is, when starting, when the rolling of the wheel due to upshifting while driving is large and small, when suddenly downshifting or downhill while driving, etc. The boosting curve 4 is set by sorting the connection pressure states that can be connected in time into several types (four types of A, B, C, and D in the present case). The boosting curve 4 can be freely set without being limited to these four types. Next, the operation of the above configuration will be described. The power transmitted from the engine is always connected by the input clutch 5 during operation of the tractor, and the power transmitted from the input clutch 5 is transmitted to the main transmission unit 6 by connecting the switching clutch 3. As shown in FIG. 4, the main transmission section 6 is operated by operating a main transmission shift switch 20 provided on the auxiliary transmission shift lever 19 to switch the first speed and the second speed to 1-2.
The speed shift solenoid valve 23 and the synchro hydraulic cylinder 27 are operated, and the third and fourth speeds are shifted by operating the 3-4 speed shift solenoid valve 24 and the synchro hydraulic cylinder 28 to transmit power to the auxiliary transmission portion 7. . The sub-transmission portion 7 is provided with the sub-transmission shift lever 1.
By the operation of No. 9, the shift speed is changed to the H speed, the M speed, the L speed, and the LL speed by operating each shift solenoid valve and the synchro hydraulic cylinder. 16 by the combination of the main transmission section 6 and the sub transmission section 7.
It is possible to perform a speed change of about a step. In this automatic transmission mechanism, both the main transmission unit 6 and the sub transmission unit 7 perform a synchronous gear shift, so that the main transmission unit 6 is operated when the main transmission shift switch 20 is operated and when the sub transmission unit 7 is operated. When the sub-shift lever 19 presses the sub-shift lever sensor 22 in the shift passage 21 to turn it on, the shift clutch 3 is always "disengaged" and the shift is controlled. Power is transmitted from the auxiliary transmission portion 7 to the rear wheel differential device 8, and the power branched from the auxiliary transmission portion 7 is transmitted from the 4WD device 10 to the front wheel drive shaft via the front wheel clutch 9. The power branched from the input clutch 5 is transmitted to the PTO transmission unit 12 via the PTO clutch 11. The "on / off" operation of the switching clutch 3 is automatically performed when the tractor starts moving or when the main transmission unit 6 and the sub transmission unit 7 perform a shift shift. This will be described with reference to the flowchart shown in FIG. First, the controller 13 reads the main shift position sensor 16 and the auxiliary shift position sensor 17 and then checks whether the shift change is completed. In the case of YES at this check point, the theoretical rotational speed of the wheel is calculated from the engine rotational speed and the shift position, and it is checked whether the pressure increase of the switching clutch 3 has started. In the case of YES at this check point, the boosting curve 4 that can be connected to the switching clutch 3 with the shortest time in the shortest time, which is predicted from the engine speed, the shift position, and the rolling state of the wheels, is determined.
Next, the boost output of the electromagnetic proportional pressure control valve 2 is determined based on the predicted value, and the output is determined based on the determination. When the shift change is completed, if the check point is NO, the control jumps to the output point of the electromagnetic proportional pressure control valve 2. Also,
At the time of the boost start check, N
In the case of O, check whether the pressure is increasing
If the check point is YES, the control jumps to the boost output determination point of the electromagnetic proportional pressure control valve 2 and returns to NO
In the case of, it is checked whether or not the boosting is completed. If the checkpoint is YES, the electromagnetic proportional pressure control valve 2 is boosted, and if NO, the boosted output is turned off.
Let it. At the decision point of the pressure increase curve 4, the predicted value of the pressure increase state of the connection pressure of the switching clutch 3 calculated by the controller 13 for selecting the pressure increase curve 4 is determined by using a predetermined value of the pressure increase curve 4. According to the selection table, the calculation of the predicted value by the controller 13 may be omitted, and the connection time of the switching clutch 3 may be further reduced. As shown in FIG. 7, this selection table shows that when starting (T), there are four shift speed shift positions, namely, extremely low speed, low speed, medium speed, and high speed (T). The four items, in which the rolling of the wheels due to the wheel is small (S), the wheel rolling is large (R), and the sudden downshift or downhill running (Z), are developed in the lower order, respectively. Take the items in the vertical column, and set the engine speed high in the horizontal column,
The four items of medium, low and extremely low are combined and each curve (A,
(B, C, D) is set by symbolizing the predicted value. In the automatic shift control as described above, electronic control is performed by detection by various sensors and the action of an actuator such as a hydraulic cylinder. However, when an abnormality occurs in these sensors, the shift shift operation is disabled. There is a possibility that it becomes. Therefore, when the sensors are abnormal, it is necessary to set the operation completion time of the actuator capable of shifting accurately without the information of the shift shift as short as possible. Conversely, if it is too short, the shift cannot be performed. ,
The maximum value (timer value) of the operation completion time during normal operation is stored in the controller 13, and when the sensors are abnormal, the output of the actuator is performed based on the stored value (timer value). Can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side view showing a gear train of a transmission. FIG. 2 is a block diagram showing an electronic control circuit by a controller. FIG. 3 is a hydraulic circuit diagram illustrating a shift operation of a main shift and an operation state of a forward / reverse switching clutch unit. FIG. 4 is a perspective view showing a shift operation of a subtransmission shift lever. FIG. 5 is a schematic diagram of a pressure increase curve showing a connection pressure effect of a switching clutch. FIG. 6 is a flowchart of a connection operation of a switching clutch during a shift shift. FIG. 7 is a selection table set in advance to select a boost curve. [Description of Signs] 3 Switching clutch 6 Main transmission section 7 Sub transmission section 13 Controller 14 Engine rotation sensor 15 Wheel rotation sensor 16 Shift position sensor 27 Hydraulic cylinder 28 Hydraulic cylinder 19 Sub transmission shift lever

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-38136 (JP, A) JP-A-60-256629 (JP, A) JP-A-2-17265 (JP, A) JP-A 61-38 189356 (JP, A) JP-A-60-11754 (JP, A) JP-A-3-41258 (JP, A) JP-A-2-236059 (JP, A) JP-A-62-215155 (JP, A) JP-A-59-217044 (JP, A) JP-A-61-291230 (JP, A) JP-A-59-219551 (JP, A) Japanese Utility Model Application No. 58-90833 (JP, U) Japanese Utility Model Application Model No. 3-60127 (JP, U) JP-A 3-98358 (JP, U) JP-A 61-14244 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16D 48/00-48 / 12 F16H 59/00-61/12 F16H 61/16-61/36 F16H 63/00-63/48

Claims (1)

(57) [Claims 1] An upholstery provided on the handle of the shift lever 19.
Operate the up / down shift switch 20 to shift gears.
The main transmission section 6 and the shift lever 19
Sub-transmission unit that shifts by moving in the front-rear direction within 21
7, a hydraulic switching clutch 3 for switching the traveling direction of the aircraft
And the switching clutch 3 is disengaged during shifting.
Later, the actuators of the main transmission section 6 operate 27 and 28.
The main transmission 6 is switched to a predetermined position, and
Farming configured to be connected with the switching clutch 3
In an industrial vehicle, the engine speed and the speed
According to the shift position and the rolling state of the running wheels
Controls the connection pressure pattern of the switching clutch 3 that is determined
The map information is stored in advance in the
Selects connection pressure pattern of switching clutch 3 based on information
A transmission device for agricultural work vehicles that is changed .