JP4078783B2 - Automatic clutch device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic clutch device for a vehicle that is particularly applied to a large vehicle such as a tractor.
[0002]
[Prior art]
Recently, in order to reduce the burden on the driver, there are many examples in which an automatic transmission is employed even in a large vehicle such as a tractor or a truck. In this case, the optimum gear stage corresponding to the vehicle speed is determined according to the map, and upshifting / downshifting is automatically performed according to acceleration / deceleration of the vehicle.
[0003]
On the other hand, such an automatic transmission generally includes an automatic clutch device that automatically connects and disconnects a friction clutch with an actuator. According to this, at the time of shifting, the clutch is automatically disconnected before the gear is released, and the clutch is automatically connected after the gear is engaged. Some perform so-called start control. In this case, the clutch is disengaged and held when the vehicle is stopped, the gear of the transmission is put into the start stage, and then the accelerator is waiting. When the driver depresses the accelerator, the clutch is gradually automatically connected accordingly.
[0004]
[Problems to be solved by the invention]
On the other hand, when the accelerator is returned at a low vehicle speed near the start time, the clutch is automatically disengaged to prevent engine stall. Originally, in terms of feeling, it is preferable to disengage the clutch as slowly as possible at low vehicle speeds.
[0005]
However, the driver may suddenly return the accelerator for some reason during the start, and there is a risk that the engine will stall if the clutch is slowly released until this time. That is, when the clutch is in the half-clutch state in the middle of connection, even if the accelerator is returned, the clutch disengagement is not in time, and in this case, the engine is stalled.
[0006]
Accordingly, an object of the present invention is to prevent engine stall when the accelerator is returned when the vehicle starts.
[0007]
[Means for Solving the Problems]
  The present inventionBetween the vehicle engine and the transmissionA friction type clutch, a clutch actuator for connecting / disconnecting the clutch, and a clutch position detecting means for detecting a stroke of the clutch drive;Gear position detecting means for detecting the gear position of the transmission, vehicle speed detecting means for detecting the speed of the vehicle, accelerator opening detecting means for detecting the accelerator opening of the engine, andIn an automatic clutch device provided with a controller that commands a clutch actuator to control disengagement and contact operation of the clutch,When the accelerator opening is reduced at the start of the vehicle, the controller automatically divides the clutch, and the clutch dividing speed of the automatic dividing is based on a flag set to either ON or OFF, When the flag is ON, the speed is high, when the flag is OFF, the speed is low, and the controller detects the speed detected by the gear position detection means when setting the flag every time the automatic division occurs.The gear stage of the transmission isStartStepAt this time, the current vehicle speed V is detected by the vehicle speed detection means, and the current vehicle speed V is set to a preset high vehicle speed side threshold value V. _H Is exceeded, the vehicle speed V is set to the high vehicle speed side threshold value V. _H Lower vehicle speed side threshold value V set in advance smaller than _L When it is less than the above, the flag is turned OFF, and the vehicle speed V is the high vehicle speed side threshold value V. _H And the low vehicle speed side threshold value V _L At this time, the flag is held at either ON or OFF set at the time of the previous automatic division.Is.
[0010]
  Also,The controller automatically connects the clutch gradually from the disengagement as the accelerator opening increases when the vehicle starts,Low vehicle speed aboveLow vehicle speed side threshold V _L Is the aboveWhen the vehicle startsAbove by automatic connectionThe clutch is half clutchConnected up toVehicle speedAnd the high vehicle speed side threshold value V is set to _H Is set to a vehicle speed at which the clutch is completely connected by automatic connection when the vehicle starts.It is preferable.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[0012]
FIG. 2 shows an automatic transmission for a vehicle according to this embodiment. Here, the vehicle is a tractor that pulls the trailer, and the engine is a diesel engine. As shown in the figure, a transmission 3 is attached to the engine 1 via a clutch 2, and an output shaft 4 (see FIG. 3) of the transmission 3 is connected to a propeller shaft (not shown) to drive a rear wheel (not shown). It is supposed to be. The engine 1 is electronically controlled by an engine control unit (ECU) 6. That is, the ECU 6 reads the current engine speed and the engine load from the outputs of the engine rotation sensor 7 and the accelerator opening sensor 8, and controls the fuel injection pump 1a mainly based on these to control the fuel injection timing and the fuel injection. Control the amount.
[0013]
As shown in FIG. 3, the flywheel 1b is attached to the crankshaft of the engine, the ring gear 1c is formed on the outer periphery of the flywheel 1b, and the engine rotation sensor 7 outputs a pulse each time the teeth of the ring gear 1c pass, The ECU 6 counts the number of pulses per unit time and calculates the engine speed.
[0014]
As shown in FIG. 2, here, the clutch 2 and the transmission 3 are automatically controlled based on the control signal of the transmission control unit (TMCU) 9. The ECU 6 and the TMCU 9 are connected to each other via a bus cable or the like and can communicate with each other.
[0015]
As shown in FIGS. 2, 3, and 4, the clutch 2 is a mechanical friction clutch. The flywheel 1b on the input side, the driven plate 2a on the output side, and the driven plate 2a are in frictional contact with the flywheel 1a. Or it is comprised from the pressure plate 2b made to separate. The clutch 2 operates the pressure plate 2b in the axial direction by the clutch booster 10 and is basically automatically connected and disconnected, so that the burden on the driver can be reduced. On the other hand, in order to enable delicate clutch work at the time of very low speed back and sudden clutch disconnection in an emergency, manual connection / disconnection by the clutch pedal 11 is also possible here. This is a configuration of a so-called selective auto clutch. A clutch stroke sensor 14 for detecting the stroke of the clutch itself (that is, the position of the pressure plate 2b) and a clutch pedal stroke sensor 16 for detecting the depression stroke of the clutch pedal 11 are provided, and are connected to the TMCU 9 respectively.
[0016]
As clearly shown in FIG. 4, the clutch booster 10 is connected to the air tank 5 through two air pressure passages a and b indicated by solid lines, and operates with the air pressure supplied from the air tank 5. One passage a is for automatic clutch connection / disconnection, and the other passage b is for clutch manual connection / disconnection. One of the passages a is bifurcated, one of which is provided with a series of solenoid valves MVC1 and MVC2 for automatic connection / disconnection, and the other is provided with an emergency solenoid valve MVCE. A double check valve DCV1 is provided at the branch junction. A hydraulically operated valve 12 attached to the clutch booster 10 is provided in the other passage b. A double check valve DCV2 is also provided at the junction of both passages a and b. The double check valves DCV1, DCV2 are differential pressure actuated three-way valves.
[0017]
The solenoid valves MVC1, MVC2, and MVCE are ON / OFF controlled by the TMCU 9. When ON, the upstream side communicates with the downstream side, and when OFF, the upstream side is shut off and the downstream side is opened to the atmosphere. First, the automatic side will be described. The electromagnetic valve MVC1 is simply turned ON / OFF in accordance with the ON / OFF of the ignition key. The ignition key is OFF, that is, it is OFF while the vehicle is stopped, and the air pressure from the air tank 5 is shut off. The electromagnetic valve MVC2 is a proportional control valve and can freely control the amount of supply or exhaust air. This is to control the clutch connection / disconnection speed. When the solenoid valves MVC1 and MVC2 are both ON, the air pressure in the air tank 5 is switched to the double check valves DCV1 and DCV2 and supplied to the clutch booster 10. As a result, the clutch is disconnected. When the clutch is connected, only the MVC 2 is turned off, whereby the air pressure of the clutch booster 10 is discharged from the MVC 2 and the clutch is disconnected.
[0018]
However, if an abnormality occurs in the electromagnetic valve MVC1 or MVC2 during clutch disconnection and either of them is turned OFF, the clutch is suddenly engaged against the driver's intention. Therefore, when such an abnormality is detected by the abnormality diagnosis circuit of the TMCU 9, the solenoid valve MVCE is immediately turned on. Then, the air pressure that has passed through the electromagnetic valve MVCE is switched to the reverse of the double check valve DCV1 and supplied to the clutch booster 10 to maintain the clutch disengaged state and prevent sudden clutch engagement.
[0019]
Next, the manual side will be described. The hydraulic pressure is supplied / discharged from the master cylinder 13 in response to the depression / return operation of the clutch pedal 11, and this hydraulic pressure is supplied to the hydraulic valve 12 via a hydraulic passage 13a indicated by a broken line. As a result, the hydraulic valve 12 is opened and closed, the pneumatic pressure is supplied to and discharged from the clutch booster 10, and the clutch 2 is manually connected and disconnected. When the hydraulically operated valve 12 is opened, the air pressure passing through the hydraulically operated valve 12 switches the double check valve DCV2 to reach the clutch booster 10. When the automatic connection / disconnection of the clutch interferes with the manual connection / disconnection, the manual connection / disconnection is prioritized.
[0020]
As shown in detail in FIG. 3, the transmission 3 is basically a so-called multi-stage transmission that is always meshed, and can shift to 16 forward speeds and 2 reverse speeds. The transmission 3 includes a splitter 17 and a range gear 19 as auxiliary transmissions on the input side and the output side, respectively, and a main gear stage 18 between them. Then, the engine power transmitted to the input shaft 15 is sent to the splitter 17, the main gear stage 18, and the range gear 19 in order and output to the output shaft 4.
[0021]
A gear shift unit GSU is provided to automatically shift the transmission 3, and is composed of a splitter actuator 20, a main actuator 21, and a range actuator 22 that are responsible for shifting the splitter 17, the main gear stage 18, and the range gear 19, respectively. These actuators are also pneumatically operated like the clutch booster 10 and controlled by the TMCU 9. The current positions of the gears 17, 18 and 19 are detected by a gear position switch 23 (see FIG. 2). The rotation speed of the counter shaft 32 is detected by the counter shaft rotation sensor 26, and the rotation speed of the output shaft 4 is detected by the output shaft rotation sensor 28. These detection signals are sent to TMCU9.
[0022]
In this automatic transmission, a manual mode is set, and a manual shift based on a driver's shift change operation is possible. In this case, as shown in FIG. 2, the connection / disconnection control of the clutch 2 and the shift control of the transmission 3 are performed with a shift instruction signal from a shift lever device 29 provided in the driver's seat as a signal. That is, when the driver shifts the shift lever 29a of the shift lever device 29, a shift switch built in the shift lever device 29 is activated, and a shift instruction signal is sent to the TMCU 9, and based on this, the TMCU 9 receives the clutch booster 10. Then, the splitter actuator 20, the main actuator 21 and the range actuator 22 are actuated appropriately to execute a series of gear shifting operations (clutch disengagement → gear release → gear engagement → clutch engagement). The TMCU 9 displays the current shift stage on the monitor 31. Thus, the shift switch built in the shift lever device 29 constitutes the manual shift switch of the present invention, and this manual shift switch is operated based on the operation of the shift lever 29a.
[0023]
In the shift lever device 29, R means reverse, N means neutral, D means drive, UP means shift up, and DOWN means shift down. The driver's seat is provided with a mode switch 24 for switching the shift mode between automatic and manual and a skip switch 25 for switching whether the shift is performed step by step or step skipping.
[0024]
If the shift lever 29a is put in the D range in the automatic shift mode, the shift is automatically performed according to the vehicle speed. Even in the automatic transmission mode, if the driver operates the shift lever 29a to UP or DOWN, manual upshifting or downshifting is possible. In this automatic shift mode, if the skip switch 25 is OFF (normal mode), the shift is performed one step at a time. This is effective when the loaded load is relatively large, such as when trailer is pulled. If the skip switch 25 is ON (skip mode), the gear shift is performed by skipping one step. This is effective when the trailer is not towed or when the load is light.
[0025]
On the other hand, in the manual shift mode, the shift completely follows the driver's intention. When the shift lever 29a is in the D range, no shift is performed, the current gear is held, and the shift up or down is possible only when the shift lever 29a is operated to UP or DOWN with the driver's positive intention. At this time, similarly to the above, if the skip switch 25 is OFF, the shift is performed one step at a time, and if the skip switch 25 is ON, the shift is skipped by one step. In this mode, the D range is an H (hold) range that holds the current gear stage.
[0026]
An emergency shift switch 27 is provided in the driver's seat so that when the GSU solenoid valve or the like breaks down, the gear can be shifted by manual switching of the switch 27.
[0027]
As shown in FIG. 3, in the transmission 3, the input shaft 15, the main shaft 33, and the output shaft 4 are coaxially arranged, and the counter shaft 32 is arranged in parallel below them. The input shaft 15 is connected to the driven plate 2a of the clutch 2, and the input shaft 15 and the main shaft 33 are supported so as to be relatively rotatable.
[0028]
First, the configuration of the splitter 17 and the main gear stage 18 will be described. A split high gear SH is rotatably attached to the input shaft 15. Further, main gears M4, M3, M2, M1, and MR are rotatably attached to the main shaft 33 in order from the front. The gears SH, M4, M3, M2, and M1 except for the MR are always meshed with counter gears CH, C4, C3, C2, and C1 fixed to the countershaft 32, respectively. The gear MR is always meshed with the idle reverse gear IR, and the idle reverse gear IR is always meshed with a counter gear CR fixed to the counter shaft 32.
[0029]
Each of the gears SH, M4,... Attached to the input shaft 15 and the main shaft 33 is integrally provided with a spline 36 so that the gear can be selected, and the input shaft 15 and the main shaft 33 are adjacent to the spline 36. First to fourth splines 37 to 40 are fixed. The first to fourth sleeves 42 to 45 are provided so as to be slidable back and forth by always engaging with the first to fourth splines 37 to 40. The first to fourth sleeves 42 to 45 are appropriately selected and slid to be engaged with and disengaged from the gear-side spline 36 so that gears can be engaged and released. The first sleeve 42 is moved by the splitter actuator 20, and the second to fourth sleeves 43-45 are moved by the main actuator 21.
[0030]
As described above, the splitter 17 and the main gear stage 18 have a constant meshing configuration that can be automatically shifted by the actuators 20 and 21. In particular, although a normal mechanical sync mechanism exists in the spline portion of the splitter 17, no sync mechanism exists in the spline portion of the main gear stage 18. For this reason, the sync control is performed to adjust the engine rotation and the gear speed so that the gear can be shifted without the sync mechanism. Here, in addition to the main gear stage 18, the splitter 17 is also provided with a neutral position so as to take a so-called rattling noise (see Japanese Patent Application No. 11-319915).
[0031]
Next, the configuration of the range gear 19 will be described. The range gear 19 employs a planetary gear mechanism 34 and can be switched to either a high or low position. The planetary gear mechanism 34 includes a sun gear 65 fixed to the rear end of the main shaft 33, a plurality of planetary gears 66 meshed with the outer periphery thereof, and a ring gear 67 having internal teeth meshed with the outer periphery of the planetary gear 66. Become. Each planetary gear 66 is rotatably supported by a common carrier 68, and the carrier 68 is connected to the output shaft 4. The ring gear 67 has a tube portion 69 integrally, and the tube portion 69 is fitted on the outer periphery of the output shaft 4 so as to be relatively rotatable, and constitutes a double shaft together with the output shaft 4.
[0032]
The fifth spline 41 is provided integrally with the pipe portion 69. An output shaft spline 70 is integrally provided on the output shaft 4 adjacent to the rear of the fifth spline 41. A fixed spline 71 fixed to the transmission case side is provided adjacent to the front of the fifth spline 41. A fifth sleeve 46 is provided so as to be slidable back and forth by always engaging with the fifth spline 41. The movement of the fifth sleeve 46 is performed by the range actuator 22. A synchro mechanism exists in each spline portion of the range gear 19.
[0033]
When the fifth sleeve 46 moves forward, it engages with the fixed spline 71, and the fifth spline 41 and the fixed spline 71 are connected. As a result, the ring gear 67 is fixed to the transmission case side, and the output shaft 4 is rotationally driven at a reduction ratio greater than 1. This is the low position.
[0034]
On the other hand, when the fifth sleeve 46 moves rearward, it engages with the output shaft spline 70, and the fifth spline 41 and the output shaft spline 70 are connected. As a result, the ring gear 67 and the carrier 68 are fixed to each other, and the output shaft 4 is directly driven with a reduction ratio of 1. This is the high position.
[0035]
In this way, in this transmission 3, on the forward side, it is possible to shift to two stages of high and low by the splitter 17, four stages of the main gear stage 18, and two stages of high and low by the range gear 19, for a total of 2 × 4 X2 = Shift to 16 stages. On the reverse side, the speed can be changed to two stages by switching between high and low only by the splitter 17.
[0036]
Next, each actuator 20, 21, 22 will be described. These actuators are composed of a pneumatic cylinder that is operated by the air pressure of the air tank 5 and a solenoid valve that switches supply and discharge of air pressure to and from the pneumatic cylinder. These solenoid valves are selectively switched by TMCU 9 to selectively actuate the pneumatic cylinder.
[0037]
The splitter actuator 20 includes a pneumatic cylinder 47 having a double piston and three electromagnetic valves MVH, MVF, and MVG. When the splitter 17 is set to neutral, MVH / ON, MVF / OFF, and MVG / ON are set. When the splitter 17 is set to high, MVH / OFF, MVF / OFF, and MVG / ON are set. When the splitter 17 is set to low, MVH / OFF, MVF / ON, and MVG / OFF are set.
[0038]
The main actuator 21 includes a pneumatic cylinder 48 having a double piston and responsible for the operation on the select side, and a pneumatic cylinder 49 having a single piston and responsible for the operation on the shift side. A plurality of solenoid valves MVC, MVD, MVE and MVB, MVA are provided for each pneumatic cylinder 48 and 49, respectively.
[0039]
The select-side pneumatic cylinder 48 moves downward in the figure when MVC / OFF, MVD / ON, and MVE / OFF, and can select 3rd, 4th, or N3 of the main gear, and MVC / ON, MVD / OFF, MVE / When ON, it becomes neutral, and the 1st, 2nd or N2 of the main gear can be selected, and when it is MVC / ON, MVD / OFF, or MVE / OFF, it moves upward in the figure, and the main gear Rev or N1 can be selected.
[0040]
The shift side pneumatic cylinder 49 is neutral when MVA / ON, MVB / ON, and can select N1, N2 or N3 of the main gear, and moves to the left side of the figure when MVA / ON, MVB / OFF. 2nd, 4th or Rev can be selected, and when MVA / OFF or MVB / ON, it moves to the right side of the figure, and 1st or 3rd of the main gear can be selected.
[0041]
The range actuator 21 includes a pneumatic cylinder 50 having a single piston and two electromagnetic valves MVI and MVJ. The pneumatic cylinder 50 moves to the right side of the diagram when MVI / ON and MVJ / OFF, and moves the range gear to the high side when MVI / OFF and MVJ / ON, and sets the range gear to low.
[0042]
Incidentally, a counter shaft brake 27 is provided on the counter shaft 32 in order to brake the counter shaft 32 during the sync control. The countershaft brake 27 is a wet multi-plate brake and is operated by the air pressure of the air tank 5. An electromagnetic valve MV BRK is provided to switch between supply and discharge of the air pressure. When the solenoid valve MV BRK is ON, pneumatic pressure is supplied to the countershaft brake 27, and the countershaft brake 27 is activated. When the solenoid valve MV BRK is OFF, the air pressure is discharged from the countershaft brake 27, and the countershaft brake 27 is deactivated.
[0043]
Next, the contents of the automatic shift control will be described. The TMCU 9 stores a shift-up map shown in FIG. 5 and a shift-down map shown in FIG. 6, and the TMCU 9 executes automatic shift according to these maps in the automatic shift mode. For example, in the shift-up map of FIG. 5, the shift-up diagram from gear stage n (n is an integer from 1 to 15) to n + 1 is determined by a function of accelerator opening (%) and output shaft rotational speed (rpm). It has been. On the map, only one point is determined from the current accelerator opening (%) and the output shaft speed (rpm). During vehicle acceleration, the rotational speed of the output shaft 4 connected to the wheels gradually increases. Therefore, in the normal automatic transmission mode, every time the current point exceeds each diagram, the upshift is performed by one step. At this time, if it is the skip mode, the diagram is alternately shifted one by one and shifted up by two stages.
[0044]
Similarly, in the shift-down map of FIG. 6, the shift-down diagram from the gear stage n + 1 (n is an integer from 1 to 15) to n is a function of the accelerator opening (%) and the output shaft speed (rpm). It is decided by. On the map, only one point is determined from the current accelerator opening (%) and output shaft speed (rpm). Since the rotation speed of the output shaft 4 gradually decreases during deceleration of the vehicle, in the normal automatic transmission mode, every time the current point exceeds each diagram, a downshift is performed by one step. In the skip mode, the diagram is alternately shifted one by one and shifted down by two stages.
[0045]
On the other hand, in manual mode, the driver can freely shift up and down regardless of these maps. In the normal mode, one shift can be achieved by one shift change operation, and in the skip mode, two shifts can be achieved by one shift change operation.
[0046]
The current accelerator opening is detected by the accelerator opening sensor 8, and the current output shaft rotation speed is detected by the output shaft rotation sensor 28. In particular, the TMCU 9 converts the current vehicle speed from the current value of the output shaft speed, and displays this on the speedometer. That is, the vehicle speed is indirectly detected from the output shaft speed, and the output shaft speed and the vehicle speed are in a proportional relationship.
[0047]
Next, engine stall prevention control when the vehicle starts according to the present invention will be described.
[0048]
In this apparatus, the following start control is performed at the time of vehicle start, and it can start easily only by a driver's accelerator work. That is, when the vehicle is stopped (near the vehicle speed zero), the clutch is disengaged, and the transmission is in the starting position, the accelerator is waiting. When the driver depresses the accelerator pedal, the accelerator opening increases and the clutch Are gradually connected automatically and the vehicle is started.
[0049]
On the other hand, when the driver returns the accelerator when starting, the clutch is automatically disconnected. It is the present invention that the dividing speed at this time is changed according to the vehicle speed.
[0050]
That is, when starting, it is preferable in terms of feeling that the clutch is disengaged as slowly as possible. This is because if the engine is turned off quickly, the engine torque applied to the drive system is released at once, and the drive system twists out suddenly. However, there is a risk that the engine will stall if the clutch is slowly disengaged until the driver suddenly returns the accelerator, such as when the vehicle gets stuck in the middle of departure. That is, the vehicle speed is close to zero in the half-clutch state in the middle of clutch engagement, and if the clutch is slowly disengaged in this state, the clutch disengagement is not substantially in time, and there is a risk of stalling. In particular, when the accelerator is returned with the clutch being deeply met near the vehicle speed zero, such as when starting on a slope using a side brake together with a full load, engine stall is likely to occur significantly.
[0051]
Therefore, in this apparatus, the clutch separation speed is changed as follows to prevent engine stall at the time of start. FIG. 1 shows a flowchart for determining the clutch separation speed.
[0052]
As shown in the figure, the TMCU 9 first determines in step 101 whether or not the current gear is a low speed. The low speed stage is a gear stage that is equal to or less than the start stage at the time of loading (when trailer is towed). Here, since the starting stage is set to the fourth speed, it is determined in step 101 whether or not the current gear stage is the fourth speed or less. The starting stage when there is no cargo (when the trailer is not towed) is 9th gear. When the current gear stage is the low speed stage, the process proceeds to step 102, and when the current gear stage is other than the low speed stage, this control is terminated.
[0053]
In step 102, the current vehicle speed V is set to a preset high vehicle speed side threshold value V._HCompare with High vehicle speed side threshold V_HAs the vehicle speed, a vehicle speed is selected so as to be in a state after the clutch is completely connected when the vehicle starts, and is set to 9 km / h here. The vehicle speed V is a high vehicle speed side threshold value V._HWhen it is larger, the routine proceeds to step 103 where the vehicle speed V is higher than the vehicle speed side threshold value V._HThe process proceeds to step 106 in the following cases.
[0054]
When the process proceeds to step 103, the flag FLAG is turned ON, and then the process proceeds to step 104 to determine whether or not the flag FLAG is ON. Since it is ON here, the process proceeds to step 105, the clutch separation speed is set to a low speed, and this flow is terminated. In other words, when the vehicle speed is sufficiently high, there is no fear of engine stall, so the clutch separation speed is set to a low speed to improve the feeling.
[0055]
On the other hand, when the process proceeds from step 102 to step 106, the present vehicle speed V is set to the preset low vehicle speed side threshold value V._LCompare with Low vehicle speed side threshold V_LThe vehicle speed is selected so that the clutch is in a half-clutch state when the vehicle starts, and is 2 km / h here.
[0056]
Vehicle speed V is low vehicle speed side threshold V_LWhen it is smaller, the routine proceeds to step 107 and the flag FLAG is turned OFF. Thereafter, the process proceeds to step 104 to determine whether or not the flag FLAG is ON. Here, since the flag FLAG is OFF, the routine proceeds to step 108, the clutch separation speed is increased, and this flow is terminated. In this way, when the vehicle speed is near zero, there is a possibility of engine stall. Therefore, the clutch separation speed is set to be high, and the clutch is quickly disengaged when the accelerator is suddenly returned. As a result, engine stall can be prevented.
[0057]
In step 106, the vehicle speed V is set to the low vehicle speed side threshold value V._LWhen judged as above, that is, V_L≦ V ≦ V_HIn this case, the process goes to step 104 without changing the flag. This is to provide hysteresis.
[0058]
Since the clutch separation speed is changed in accordance with the vehicle speed in this way, engine stall can be prevented in advance, and the clutch separation speed can be reduced to the lowest possible vehicle speed to achieve a balance with the feeling. Here, the clutch separation speed is switched between high speed and low speed to increase the vehicle speed side (V> V_H(V_L)) At low speed and low speed (V <V_L(V_H)) Is fast.
[0059]
By the way, such a change in the clutch separation speed is also effective when the vehicle coasts (in coastal running). In other words, when the vehicle is decelerated with the low speed stage and the accelerator turned back, the clutch is automatically disconnected immediately before the vehicle stops. At this time, the high vehicle speed side (V> V_H(V_L))), When the clutch is disconnected, the disconnecting speed should be low and the vehicle speed side (V <V_L(V_H)) When separating the clutch, increase the separation speed. This also prevents engine stall and improves feeling.
[0060]
As mentioned above, embodiment of this invention is not restricted to the above-mentioned thing. The gear stage for performing this control is not limited to the fourth speed or lower, and the threshold value is not limited to 2 km / h or 9 km / h. The clutch separation speed can be switched to three or more stages, or can be changed steplessly. Applicable vehicles are not limited to tractors.
[0061]
【The invention's effect】
The present invention exhibits the following excellent effects.
[0062]
(1) When the vehicle starts, the engine stall can be prevented when the accelerator is returned.
[0063]
(2) A balance between engine stall prevention and feeling can be achieved.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a clutch disengagement speed determination method according to the present invention.
FIG. 2 is a configuration diagram showing a vehicle automatic transmission according to the embodiment.
FIG. 3 is a configuration diagram showing an automatic transmission.
FIG. 4 is a configuration diagram showing an automatic clutch device.
FIG. 5 is a shift-up map.
FIG. 6 is a shift down map.
[Explanation of symbols]
1 engine
2 Clutch
3 Transmission
8 Accelerator position sensor
9 Transmission control unit
10 Clutch booster
28 Output shaft rotation sensor
V vehicle speed
V_H  High vehicle speed side threshold
V_L  Low vehicle speed side threshold

Claims (2)

A friction type clutch provided between a vehicle engine and a transmission , a clutch actuator for connecting and disconnecting the clutch, a clutch position detecting means for detecting a stroke of the clutch drive, and a gear position of the transmission A gear position detecting means for detecting the vehicle speed, a vehicle speed detecting means for detecting the speed of the vehicle, an accelerator opening detecting means for detecting the accelerator opening of the engine, and a command to the clutch actuator to disengage the clutch. In an automatic clutch device comprising a controller for controlling the operation,
When the accelerator opening is reduced at the start of the vehicle, the controller automatically divides the clutch, and the clutch dividing speed of the automatic dividing is based on a flag set to either ON or OFF, When the flag is ON, the speed is high; when the flag is OFF, the speed is low; and
When the controller sets the flag for each automatic division,
When the gear position of the transmission detected by the gear position detection means is a start stage , the vehicle speed detection means detects the current vehicle speed V,
When the current vehicle speed V exceeds a preset high vehicle speed side threshold value V _H , the flag is turned ON, and the vehicle speed V is preset to be smaller than the high vehicle speed side threshold value V _H. When the vehicle speed V is less than the low vehicle speed side threshold value V _L , the flag is turned OFF, and when the vehicle speed V is the high vehicle speed side threshold value V _H or less and the low vehicle speed side threshold value V _L or more, the flag is set to the previous time. An automatic clutch device for a vehicle, which is held at either ON or OFF set at the time of automatic division . The controller automatically connects the clutch gradually from the disengagement as the accelerator opening increases when the vehicle starts,
The low vehicle speed side threshold value V _L is set to a vehicle speed such that the clutch is connected to the half-clutch state by automatic connection at the time of starting the vehicle,
2. The automatic clutch device for a vehicle according to claim 1, wherein the high vehicle speed side threshold value _VH is set to a vehicle speed at which the clutch is completely connected by automatic connection at the time of starting the vehicle.

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