JPS6353388B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a shift control method for a vehicle with an automatic transmission, and more particularly to a shift control method for controlling engine output torque during a shift period using ignition timing. In order to reduce costs by standardizing parts, the same type of automatic transmission is combined with various engines with different output performance, but in this case, it is necessary to balance the reduction of shift impact and the durability of the friction engagement device. For this reason, a hydraulic diagram of the cylinder hydraulic pressure of the frictional engagement device, an accumulator hydraulic pressure, etc. are set for each type of engine. However, there is a contradictory relationship between reducing the shift impact and increasing the durability of the friction engagement device.
Reducing the engine torque absorbed by the friction engagement device improves the durability of the friction engagement device, but increases the shift impact, and vice versa, reduces the shift impact but reduces the durability of the friction engagement device. becomes worse. Therefore, in the case of a high-output engine, in order to maintain the durability of the friction engagement device and ensure high output, suppressing the shift impact is sacrificed, and at the same time, it is necessary to reduce the difference in engine speed before and after the shift. In order to ensure durability, the shift point is shifted to the low vehicle speed side, resulting in a problem that the low speed driving range is reduced and sufficient engine performance is not achieved. SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic control method for a vehicle with an automatic transmission that can suppress shift impact while avoiding deterioration in the durability of a frictional engagement device. In order to achieve this object, the shift control method for a vehicle with an automatic transmission of the present invention starts reducing the amount of advance of the ignition timing immediately before the friction engagement device of the automatic transmission starts engaging, and When the friction engagement device is about to engage, the amount of advance of the ignition timing is maintained at a reduced constant amount, and the amount of advance is gradually increased from just before the friction engagement device ends engagement until after the engagement ends. This is a method of preventing the moment of inertia of the engine from greatly affecting the shock during gear shifting by reducing the amount of advance of the ignition timing. In reducing the engine output torque, a predetermined period of time is determined between the first time t1 as the start time of the gear shift operation and the time tk at which engagement of the frictional engagement device of the automatic transmission starts, and from the first time t1. A second time t2 after T1 has elapsed, and a second time t2 that is later than the time tk at which engagement of the frictional engagement device of the automatic transmission begins.
a third time t3 at which a second predetermined time T2 has elapsed;
A fourth time t4, at which a third predetermined time T3 has elapsed from the third time t3, and a fourth time t4, which is before the sixth time tl at which engagement of the frictional engagement device of the automatic transmission ends;
The fifth time when the fourth predetermined time T4 has elapsed from the time t4 of
and a seventh time t7 at which a predetermined time T6 has elapsed from the sixth time tl at which engagement of the frictional engagement device of the automatic transmission ends, and the frictional engagement device of the automatic transmission During the period from the second time t2 to the fourth time t4 sandwiching the time tk at which engagement begins, the amount of advance of the ignition timing is gradually reduced, and the engagement of the friction engagement device of the automatic transmission is stopped. From the fourth time t4 to the fifth time t5, the amount of advance of the ignition timing is maintained at a reduced constant amount, and the amount of advance of the ignition timing is maintained at a constant, decreased amount, and the amount of advance of the ignition timing is maintained at a constant amount, and the amount of advance of the ignition timing is maintained at a constant, decreasing amount. This method is characterized in that the amount of advance of the ignition timing is gradually increased from the fifth time t5 to the seventh time t7 with time tl in between. Therefore, according to the present invention, as a result of the engine output torque being reduced during gear shifting, the rotational variation on the engine side of the frictional engagement device quickly synchronizes with the rotational speed on the drive wheel side, and the rotational speed of the frictional engagement device is increased. The period of semi-engaged state is shortened, and the hydraulic pressure of the accumulator (=
The peak value of the rear axle torque Tr during gear shifting is reduced by reducing the cylinder oil pressure Pe) in the range A2, and furthermore, by starting to increase the engine output torque immediately before the end of engagement of the friction engagement device, the friction is reduced. At the time when the engagement of the engagement device is completed, the engine output torque is gradually increasing, so a decrease in the engine output torque does not cause a shock, and this suppresses the shift shock and improves the durability of the friction engagement device. This can be achieved in parallel with sexual improvement. Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows the entirety of a three-speed forward automatic transmission and a control device to which the present invention is applied. The hydraulic torque converter 1 has a pump impeller 2, a stator 4 fixed to a housing via a one-way clutch 3, and a turbine runner 5. The pump impeller 2 is connected to the engine crankshaft 6.
is combined with The direct coupling clutch 7 is provided in parallel with the hydraulic torque converter 1 and controls the connection between the crankshaft 6 and the turbine runner 5.
The turbine shaft 8 is connected to the turbine runner 5 and is connected via a front clutch 9 of a gearing 15 to a central shaft 10 and via a rear clutch 11 to an intermediate shaft 12 . Intermediate shaft 1
2 is connected to the housing 1 via the first brake 13
4, one-way clutch 17 and second
It can also be fixed to the housing 14 via the brake 18 of. The two planetary gear devices 19 and 20 include sun gears 21 and 22, pinions 23, and
24, ring gear 25, 26, carrier 27, 2
8, the sun gears 21 and 22 are integrally provided on the intermediate shaft 12, and the carrier 27 can be fixed to the housing 14 via a one-way clutch 33 and also via a third brake 34. Possibly, the ring gear 25 is connected to the carrier 28, the ring gear 26 is connected to the central shaft 10, and the output shaft 35 is connected to the ring gear 25. The following table is an operation table for implementing each gear stage, the numbers correspond to each engagement element, 〇 indicates the engagement state,
△ indicates that it operates only during engine braking.

[Table] The operation of each engagement element except for the one-way clutches 17 and 33 is controlled by hydraulic pressure supply to a hydraulic servo provided corresponding to the engagement element, and this hydraulic pressure supply is provided to a hydraulic control device 39. It is controlled by a 1-2 solenoid valve 40 and a 2-3 solenoid valve 41. Another solenoid valve 42 controls the hydraulic pressure supply to the hydraulic servo of the direct coupling clutch 7. A computer 43 that operates according to a predetermined program includes a CPU 45, ROM 46, RAM 47, and
It has an A/D (analog/digital converter) 48 and an I/O (input/output interface) 49,
The energizing signal and primary ignition signal sent to the solenoid valves 40, 41, 42 and the ignition device 51 are calculated based on the vehicle speed V, intake throttle opening Th, intake air flow rate Q, and the like. FIG. 2 shows the relationship between the ignition timing advance amount θa and the engine output torque Te at a predetermined intake system throttle opening and a predetermined engine speed. The engine output torque Te reaches its maximum at a predetermined advance amount θa1 before the top dead center of the combustion stroke (θa=0°), and decreases as the advance amount decreases. Therefore, it can be seen that the engine output torque during the shift period can be controlled within a predetermined range by increasing or decreasing the ignition timing advance amount θa. During non-shifting, as a general rule, θa=
θa is calculated based on the engine load (=intake air flow rate Q/engine rotation speed N) and engine rotation speed N so that θa1 is obtained. FIG. 3 shows changes in engine rotational speed N, ignition timing advance amount θa, rear axle torque Tr, and cylinder oil pressure Pc of the second brake 18 during the shift period during which the shift is performed from first gear to second gear. It shows.
The solid line shows the change in the example, and the broken line shows the change in the case where engine torque reduction control is not performed during the shift period. A shift start signal is generated at time t1. Specifically, in the hydraulic control device 39, the output to the 1-2 solenoid valve 40 that switches between the first speed and the second speed is switched from an off signal to an on signal. Gears (1st gear, 2nd gear, 3rd gear)
The speed) is set as a function of the throttle opening Th and the vehicle speed V, but if the gear position calculated based on the current data is different from the current gear position, a shift start signal is generated. In order to detect time t1, instead of using the shift start signal, brake 1 is detected.
A hydraulic switch may be provided in the oil passage that guides the hydraulic pressure to the cylinder No.8. In this case, the time when hydraulic pressure supply to the cylinder of the brake 18 is started is detected by the hydraulic pressure switch as time t1. Time t2 to t7 are set based on time t1. In Figure 3, the time intervals between adjacent times t1 to t7 are T1 to T6, respectively.
It is. The time T1 from time t1 to t2 is the advance angle amount θa
This is the time delay until the actual decrease. time tk
is the time when the engagement of the brake 18 starts, and the time
t3 is set as a time later than time tk and appropriately close to time tk. Torque Tr is from time tk to time tl
Tr increases rapidly due to the moment of inertia of the engine, but at time tl the gear changes of the components involved in gear shifting end and the gear shift ends, and Tr rapidly decreases after time tl, causing the drive system to swing back. becomes the minimum value. t5 and t6 are set as times slightly before the time when the minimum value of Tr occurs. Note that the cylinder oil pressure Pc has three pressures A1, A2, and A3 (A1, A2
is actually sloped gently upward to the right. A3 is flat. ) area, A1 occurs due to the movement of the piston, A2 occurs due to the actuation of the accumulator, and A3 occurs due to the upper limit of the cylinder oil pressure. Furthermore, instead of detecting time t1, cylinder oil pressure Pc at time tk when A1 ends
The best method is to detect this and control the ignition timing with a timer. Before time t2, the advance angle amount θa is maintained at the normal value (θa1 in FIG. 2) determined by the engine load (=intake air flow rate Q/engine rotational speed N) and the engine rotational speed N. From time t2 to time t3, the advance angle amount θa is decreased from the advance angle amount θa at time t2 at a predetermined small slope K1 with respect to the passage of unit time, and as a result, the engine output torque Te is gradually decreased. . The reason why the advance angle amount θa is decreased at a small slope is that if the advance angle amount θa is suddenly decreased, the engine output torque will decrease.
This is because if Te is rapidly decreased, the drop in rear axle torque Tr at time tk becomes large, and the sense of shock experienced by the driver increases. From time t3 to time t4, the advance angle amount θa decreases from the advance angle amount θa at time t3 at a large slope K2 (K2>K1) with respect to the passage of unit time, and from time t4 to time t5, the advance angle amount θa decreases. is maintained at the lower limit at time t4. As the engagement force of the brake 18 increases, the rear axle torque decreases due to the moment of inertia of the engine.
Tr increases rapidly, but because the engine output torque decreases due to the decrease in advance angle θa, the hydraulic pressure of the accumulator is set to a low value to reduce the rear axle torque.
It is possible to suppress the increase in Tr and reduce the rear axle torque.
The increase in Tr is significantly suppressed compared to the case without torque reduction (broken line). In addition, by reducing the engine output torque Te, the rotational speed of the engine side of the brake 18 is quickly synchronized with the rotational speed of the driving wheel side, which reduces the period in which the brake 18 is in a half-engaged state and improves the durability of the brake 18. . From time t5 to time t6, the advance angle amount θa increases from the lower limit at a large slope K3 with respect to the passage of unit time,
From time t6 to time t7, the advance angle amount θa is increased from the advance angle amount θa at time t6 at a predetermined small slope K4 (K4<K3) with respect to the passage of unit time, and at time t7, the advance angle amount θa is increased to the original value. (θa1 in FIG. 2). Therefore, the engine output torque Te at time tl has been sufficiently returned to its original value, so
A drop in the rear axle torque Tr due to fluctuations is suppressed. The slope of the advance angle θa is set to K3 at time t6.
The reason for changing from to K4 is that if K3 is set until time t7, the impact caused by the swing back and drop in the rear axle torque Tr will increase if it occurs before time t5, and this can be avoided. This is because if time t5 is set early in order to achieve this, the time for suppressing the increase in rear axle torque Tr due to the moment of inertia becomes shorter. FIG. 4 is a flowchart of a program according to the technical idea of FIG. 3. This program is executed at predetermined time intervals. In step 55, which control period defined by times t1 to t7 (each control period corresponds to T1 to T6) is detected. time t1
A predetermined timer starts operating, and the control period t1~t2, t2~t3, t3~t4, t4~ is determined from the value of this timer.
t5, t5 to t6, and t6 to t7 are detected. Step 5
In step 6, the advance angle amount θa is changed according to the control period detected in step 55. During the control period t2 to t4, θa is
During the control period t5 to t7, θa is increased by the value corresponding to K3 or K4, and during the control period t4 to t5, θa is maintained constant. FIG. 5 shows a shift diagram for upshifting in an automatic transmission with four forward speeds. The engagement start time tk of the engagement device to be engaged after the shift up and the shift end time tl change in relation to the engine load and the main line pressure corresponding to the throttle opening, so each shift line corresponds to the throttle opening. It is divided into three regions in relation to Th, and timers Tm1 to Tm9 are set for each region of each shift line. Therefore, t2 to t7 in FIG. 4 are set for each timer Tm1 to Tm9. FIG. 6 is a flowchart of a program for setting appropriate timers. This program is executed when a shift signal is generated or when a hydraulic switch detects the supply of hydraulic pressure to the frictional engagement device. In steps 60, 68, and 77, which shift up is detected is detected, and in the case of a shift up from first gear to second gear, step 61 or 62 is executed.
Step 69 or 70 is executed in the case of a shift up from second gear to third gear, and step 78 is executed in the case of a shift up from third gear to fourth gear.
Or 79 is executed. Step 61,6
2, 69, 70, 78, 79 throttle opening
It is determined whether or not Th is in the range of 0°<Th30°, 30°<Th70°, and 70°<Th, and steps 63 to 6
By executing steps 5, 71 to 73, and 80 to 82, a timer as defined in FIG. 6 is selected depending on the type of shift up and the throttle opening Th.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an automatic transmission and a control device to which the present invention is applied, FIG. 2 is a graph showing the relationship between the amount of advance of ignition timing and engine output torque, and FIG.
The figure is a graph showing changes over time in engine rotational speed and ignition timing advance amount during the shift period.
The figure is a flowchart of an embodiment of the present invention, FIG. 5 is a diagram showing the timer to be set on a shift diagram, and FIG. 6 is a flowchart of a program for setting the timer. 15...Gear device, 18...Brake, 40...
...1-2 solenoid valve, 43 ... computer, 51 ... ignition device.

Claims (1)

[Claims] 1. In reducing the amount of advance of the ignition timing to reduce the engine output torque during gear shifting, a first time t1 as the start time of the gear shifting operation;
Time tk when the frictional engagement device of the automatic transmission starts engaging
a predetermined time T1 that is earlier than the first time t1
and a third time t3, which is after the time tk at which engagement of the frictional engagement device of the automatic transmission starts and a second predetermined time T2 has elapsed from the second time t2. , a third predetermined time from the third time t3
A fourth time t4 after which T3 has elapsed and a fourth predetermined time T4 that is before the sixth time tl at which engagement of the frictional engagement device of the automatic transmission ends, and from the fourth time t4.
A fifth time t5 at which a predetermined time T6 has elapsed from a sixth time tl at which engagement of the frictional engagement device of the automatic transmission ends, and a seventh time t7 at which a predetermined time T6 has elapsed from the sixth time tl at which engagement of the frictional engagement device of the automatic transmission ends. from the second time t2 to the fourth time t4 sandwiching the time tk at which engagement of the frictional engagement device starts.
The amount of advance of the ignition timing is gradually decreased during the period from the fourth time t4 to the fifth time t5, when the frictional engagement device of the automatic transmission is being engaged. During the period from the fifth time t5 to the seventh time t7 sandwiching the sixth time tl at which the angular amount is maintained at a reduced constant amount and the engagement of the frictional engagement device of the automatic transmission ends. A shift control method for a vehicle with an automatic transmission, characterized by gradually increasing the amount of advance of ignition timing.