JPH023762A - Speed change control method for automatic speed change gear with lockup clutch - Google Patents

Abstract

PURPOSE:To reduce the generation of a speed change shock by a method wherein the rotation speed change state of the member of an automatic speed change gear is detected, and at the same time when the member starts a change in a rotation speed, torque down of an engine is started. CONSTITUTION:When a speed change is decided by means of a signal from a throttle opening sensor through a car speed sensor and an ECU 40, a speed change control device 50 performs control of a given speed change through an electric hydraulic control circuit. The rotation speed (car speed) of the output shaft of an automatic speed change gear and an engine rotation speed (crank angle sensor) are monitored. When it is detected according to the presence of engagement of a lockup clutch 73 that the member of the automatic speed change gear starts a change in a rotation speed, a torque down signal is outputted to an ECU 40, and an ignition timing or a fuel injection amount is controlled to perform torque down of an engine. This constitution always reduced the generation of a speed change shock, and enables provision of speed change transient characteristics being short in a speed change time.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a shift control method for an automatic transmission with a lock-up clutch, and more particularly, to an automatic transmission with a lock-up clutch configured to maintain good shift characteristics by changing engine torque during gear shifting. This invention relates to a speed change control method.

[Conventional technology]

The gear transmission mechanism includes a gear transmission mechanism and a plurality of frictional engagement devices, and the engagement of the frictional engagement devices is selectively switched by operating a hydraulic control device to achieve one of the plurality of gears. Automatic transmissions for vehicles configured to do this are already widely known. Such automatic transmissions for vehicles generally include a shift lever operated by the driver, a vehicle speed sensor that detects the vehicle speed, and a throttle sensor that detects the throttle opening, which is considered to reflect the engine load. The engagement state of the frictional engagement device can be automatically switched in accordance with the range of the shift lever and at least in relation to the vehicle speed and throttle opening. In addition, in recent years, lock-up clutches have been developed that are equipped with lock-up clutches in the torque converters of automatic transmissions, and mechanically directly connect the input and output sides of the torque converters as appropriate to prevent deterioration of fuel efficiency due to slipping of the torque converters. Automatic transmissions are also widely used. By the way, in the above-mentioned automatic transmission, the engine torque is changed during gear shifting to obtain good shifting characteristics, and the automatic transmission and engine integrated control is aimed at ensuring and improving the durability of the frictional engagement device. Various methods have been proposed (for example, Japanese Patent Laid-Open Nos. 55-46095 and 55-69738).
, 56-35857, 58-77138, 58-
180768, 6O-263774). That is, this -
The system part changes the amount of torque transmitted from the engine during gear shifting, and controls the amount of energy absorbed by each member of the automatic transmission or the frictional engagement device that brakes them, thereby shifting gears in a short time and with a small shift shock. The aim was to provide the driver with a good shifting sensation and to improve the durability of each frictional engagement device.

[Problems to be solved by the invention]

However, although the above control is performed using a timer, etc., which starts from the time of determining a gear shift, in reality, there are only a few cases where these can be adapted to the actual system as is, and the control accuracy is also not very good. The reality is that it is impossible to say. This is thought to be because there was no clear regulation on how to reduce engine torque. However, in order to always ensure good shifting characteristics obtained by reducing engine torque across the entire range of each transmission diagram, when and how to reduce engine torque must be clearly stipulated. Must-have. because,
Depending on how the engine's torque is reduced, a large shift shock may occur, impeding a good driving sensation, or the shift time may become longer, deteriorating the durability of the friction engagement device. . Particularly in automatic transmissions equipped with a lock-up clutch, engine torque can be changed depending on whether the lock-up clutch is engaged or not engaged. Unless they are made different, truly good shifting characteristics cannot be maintained.

OBJECTIVE OF THE INVENTION 1 The present invention has been made in view of such conventional problems, and specifically defines how to reduce the engine torque in an automatic transmission equipped with a lock-up clutch, and improves the speed change line. It is an object of the present invention to provide a speed change control method for an automatic transmission with a lock-up clutch that can perform good speed change control over the entire region of the figure. [Means for Solving the Problems] As summarized in FIG. 1, the present invention provides a lock-up clutch configured to maintain good shifting characteristics by changing engine torque during shifting. A speed change control method for an automatic transmission equipped with an automatic transmission includes a step of detecting whether or not the lock-up clutch is in an engaged state at the time of determining a speed change, a step of detecting an engine rotation speed Ne, and an output shaft rotation speed of the automatic transmission. The procedure for detecting NO and when the lock-up clutch is in the engaged state at the time of gear change judgment are as follows:
The engine torque is changed by detecting that the engine rotation speed Ne has become smaller than the rotation speed Ne+ (=ILXNo) obtained from the product of the gear ratio IL before shifting and the output shaft rotation speed No of the automatic transmission. is started, and when the lock-up clutch is in the disengaged state, the engine torque is increased by detecting that the currently detected engine rotation speed Nei has become smaller than the previously detected engine rotation speed Nei-1. The above objective is achieved by including a procedure for starting a change of. [Operation 1] In the present invention, the state of change in the rotational speed of a member of the automatic transmission is detected, and the torque reduction of the engine is started at the same time as the member starts changing the rotational speed. As a result, engine torque control can always be performed in synchronization with the shift state of the automatic transmission, and good shift characteristics can be obtained. In the present invention, the method for detecting the start of a change in the rotational speed of the member is changed depending on whether or not the lock-up clutch is engaged at the time of determining the gear shift. That is, when the lock-up clutch is engaged, the rotation speed Ne1 (=NoXIL> obtained from the product of the gear ratio IL before shifting and the output shaft rotation speed No of the automatic transmission is calculated, and Compared with the speed Ne, Ne<N
It is determined that the rotational speed change of the member starts when the rotational speed becomes ET. On the other hand, when the lock-up clutch is not engaged when determining a gear shift, the engine rotation speed Ne is monitored, and when the currently detected engine rotation speed Nei becomes smaller than the previously detected engine rotation speed Ne It is determined that the rotation speed has started to change. As a result, regardless of whether the lock-up clutch is engaged or disengaged, it is possible to accurately determine the point at which the rotational speed of the member changes, and to properly control the engine torque.
start). Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 6 is an overall schematic diagram of an automatic transmission combined with an intake air amount sensing type automobile electronic fuel injection engine to which the present invention is applied. Air taken in from the air cleaner 10 is sent to an air flow meter 12, a throttle valve 14, a surge tank 16, and an intake manifold 18 in order. This air is mixed with fuel injected from the injector 22 near the intake port 20, and is further sent to the combustion chamber 26A of the engine body 26 via the intake valve 24. Combustion chamber 2
Exhaust gas generated as a result of combustion of the air-fuel mixture in the exhaust valve 28, the exhaust boat 301 and the exhaust manifold 3
2 and exhaust pipe 34 to the atmosphere. The air flow meter 12 is provided with an intake temperature sensor 100 for detecting intake temperature. The throttle valve 14 rotates in conjunction with an accelerator pedal (not shown) provided at the driver's seat. This throttle valve 14 is provided with a throttle sensor 102 for detecting its opening degree. Further, a water temperature sensor 104 for detecting the engine cooling water temperature is disposed in the cylinder block 26B of the engine main body 26, and a water temperature sensor 104 for detecting the oxygen concentration in the collecting part of the exhaust manifold 32 is disposed. 02 sensor 106 is provided. Further, the destroyer 38, which has a shaft rotated by the crankshaft of the engine body 26, is provided with a crank angle sensor 108 for detecting the crank angle from the rotation of the two front wheels. In addition, the automatic transmission A/T has
A vehicle speed sensor 100 for detecting the vehicle speed from the rotational speed of the output shaft, a shift position sensor 112 for detecting the shift position, and a hydraulic oil temperature sensor 113 for detecting the hydraulic oil temperature are provided. There is. Each of these sensors 1001102.104.106.1
The output of o8.110.112.113 is input to an engine computer (hereinafter referred to as ECU) 40. E
The CU 40 calculates the fuel injection amount using input signals from each sensor as parameters, and controls the injector 22 to inject fuel only at a predetermined time corresponding to the fuel injection l. Note that an idle rotation control pulse 7 (l5C
V) 42 is provided, and the idle rotation speed is controlled by a signal from the ECU 40. As detailed in the seventh factor, the ECLJ40 has a central processing unit (CPU) 4 consisting of a microprocessor.
0A, a memory 40B for storing control programs and various data, and a memory 40B for converting analog signals from the intake temperature sensor 1001, water temperature sensor 104, transmission hydraulic oil temperature sensor 113, etc. into digital signals and importing them. , an analog-to-digital converter (A/
D converter) 40C and the throttle sensor 102
, O2 sensor 106, crank angle sensor 1°8, vehicle speed sensor 110, shift position sensor 112, etc.
D, and an ignition signal to the ignition coil 44, a fuel injection signal to the injector 22, an idle rotation control signal to the l5CV 42, and an ECT computer 5 for the automatic transmission A/T according to the arithmetic processing result of the CPU 40A.
and an output interface circuit 40E for outputting a signal to 0. On the other hand, the ECT computer 50 includes a central processing unit (CPU) 50A consisting of a microprocessor, and a memory 50B for storing control programs, various data, etc.
, an input interface circuit 500 for inputting outputs from the throttle sensor 102, vehicle speed sensor 110, shift position sensor 112, pattern select switch 1201, brake lamp switch 122, cruise control switch 124, and overdrive switch 126, and the CPU 50A. According to the calculation result of automatic transmission A/T, solenoids S+, S2,
It also includes an output interface circuit 50E for outputting a control signal to Ss. The automatic transmission A/T includes a 2-3 shift valve 61 driven by the solenoid S1, a 1-2 shift valve 62 and a 3-4 shift valve 63 driven by the solenoid S2, and a 3-4 shift valve 63 driven by the solenoid $3. A lock-up clutch control valve 64 is provided, and a third speed section unit 71 for obtaining a gear ratio configuration of first speed to third speed is controlled by shift valves 61 and 62.
An overdrive unit 72 for obtaining an overdrive gear ratio is controlled by the shift valve 63,
A lock-up clutch 73 that mechanically directly connects the input and output sides of the torque converter is controlled by the lock-up clutch control valve 64. Furthermore, this ECU 40 utilizes the fact that the reciprocal of the time interval of the signal outputted from the crank angle sensor 108 for each crank angle 30' is proportional to the engine rotational speed, so that the output signal from the crank angle sensor 1o8 is Based on this calculation, the engine rotation speed is calculated. Furthermore, this ECU 40 receives shift information (shift determination, shift command, lock-up clutch engagement permission, etc.) from the ECT computer 5o, executes engine torque down control, and outputs this control information to the ECT computer 50. Based on this information, the ECT computer 50 issues a lock-up clutch release command and checks whether the above control is being performed reliably. In this embodiment, the ECU 40 and the ECT computer 50 are separate units, and the ECU 40 determines and executes the engine torque down timing, but in the present invention, the number of control devices or the control division thereof is It does not limit the area. Next, the operation of the embodiment of the present invention will be explained using FIGS. 2 and 3. That is, FIG. 2 and FIG. 3 show an embodiment when it is determined that a gear shift should be performed to perform a power-on upshift (an upshift performed with the accelerator depressed). Further, in this embodiment, a case is shown in which the lock-up clutch 73 is turned on at the time of determining the speed change. First, at point A in Figure 2, the vehicle speed and throttle opening (
The speed change judgment is made according to the engine load), and the timer T+
After a considerable amount of time has elapsed, a shift command is issued at point B. Note that the reason why the timer T1 is provided with a delay is to issue a shift command based on the last shift decision made when two or more shift decisions are made within a short period of time. After the shift command is issued, monitoring of the output shaft rotational speed No. of the automatic transmission and the engine rotational speed N'e is started in order to detect the state of change in the rotational speed of the members of the automatic transmission. In this example, a value Ne 1 determined from the low gear ratio (gear ratio before shifting) IL and the output shaft rotation speed No is calculated,
When Ne < Net t is 01 times in a row, it is determined that it is the start time of the rotational speed change section (hereinafter referred to as inertia phase) of the member (point C in Figure 2). Here, 01 is a constant for preventing detection errors. Note that this nl may be changed depending on the throttle opening, the type of shift, etc. Simultaneously with the detection of the start timing of this inertia phase, a command to release the lock-up clutch is issued, and a command to reduce the torque of the engine is issued. The speed of engine torque down is done as fast as possible. The amount of engine torque reduction is determined by selecting a corresponding value from a map set in advance according to the engine load (throttle opening), gear shift, hydraulic oil temperature, and shift pattern at the time of the engine torque reduction command. Determined by The reason for detecting the hydraulic oil temperature is to take into consideration the fact that generally when the hydraulic oil temperature rises, the oil pressure of the frictional engagement device tends to decrease due to an increase in pressure leakage inside the control device. Therefore, it is desirable to perform a correction that increases the amount of engine torque reduction as the hydraulic oil temperature increases. If there is a change in throttle opening during gear shifting (θ^ → θ days)
, the opening degree is sequentially corrected to a value corresponding to day 0. In this case, when the throttle opening becomes larger, the amount of engine torque reduction is also corrected to become larger. The engine torque return command timing is performed near the end of the inertia phase. In this example, the turbine synchronous speed NTI is calculated from the output shaft rotational speed No of the automatic transmission and the high speed gear ratio ■H, and when the engine rotational speed Ne reaches a speed higher than the turbine synchronous speed NTT by a constant N1, (Net> is determined to be near the end of the inertia phase (point D). That is, NOXIH+N1
This is the case when ≧Ne is established. Here, the constant N1 corresponds to a correction term for more accurately determining the end of the inner layer phase according to the state of the automatic transmission, and depends on the throttle opening θc1 at the time of calculation, the type of shift, and the shift pattern. The value set in advance is used. The engine torque is gradually restored over a period of 7 seconds from the time when the engine torque restoration command is issued (point D). As shown in FIG. 3, for example, this time To uses a value set in advance corresponding to the throttle opening θc1 speed change type and shift pattern at the time of the return command. In addition, in the third factor, an example of a map consisting of each throttle opening θ0...θ7 and the type of shift when the shift pattern is N (normal pattern) is shown.
As the throttle opening increases, To increases,
In addition, when the type of shift is a higher gear, To is set to be smaller. For example, if the shift pattern is P (power pattern), each value in the normal pattern is multiplied by 1.1, and if it is E (economy pattern), the corresponding value in the normal pattern is multiplied by 0. The values are set so that they are each multiplied by 9. Of course, this To may be set in advance in a map similar to N (normal pattern) for each shift pattern. Also, in Fig. 3, θ0・
... θ7 may be obtained by dividing the range from fully closed throttle to fully open throttle into nonlinear magnitudes. After the engine torque has been restored at point E in the diagram,
From the shift command, a lock-up clutch engagement permission command is issued by the timer T3 (point F). This timer T3
is set in advance to a value such that the lock-up clutch engagement permission command is easily executed to complete engine torque recovery. Lock-up clutch 73 is OFF when determining gear shift
In this case, since the engine and automatic transmission are not directly connected, the engine rotation speed Ne after the shift command is monitored as a means of detecting the start of the inertia phase, and Net<N1-I is detected 02 times in a row. I will decide in time. That is, the detected value Nei of the current engine rotation speed
The start of the inertia phase is determined when Nei becomes smaller than the previous detected engine speed Nei two times in a row. Here, n2 is a constant for preventing detection errors. Note that n2 may be changed depending on the throttle opening degree, type of speed, etc. The rest is the same as described above, so redundant explanation will be omitted. Whether the lock-up clutch 73 is ON or OFF is determined by the solenoid 83 (seventh solenoid) that operates the lock-up clutch control valve 64 that controls the lock-up clutch 73.
All you have to do is check the status (see figure). Next, basic speed change transient characteristics in the control of the embodiment described above will be explained using FIGS. 4 and 5. As shown in FIG. 4, in this embodiment, the engine rotational speed Ne after the shift command, or the output shaft rotational speed No. of the automatic transmission, and the throttle opening degree θ are monitored, and the inertia phase is detected to determine the engine torque. A lock-up clutch release command is issued at the same time when the engine is lowered. Therefore, firstly, the transmission characteristics are improved by reducing the engine torque. In other words, if the gear shift is performed without reducing the engine torque, the shift time becomes longer as shown by the broken line in Figure 4, which is disadvantageous in terms of the durability of the rIltlI engagement device. *m If the operating pressure of the engagement device is increased, a problem arises in that the shift shock increases as shown by the two-dot chain line in the figure, but both of these problems are overcome in this embodiment. Second, since the lock-up clutch is released during the inertia phase (point e), there is no increase in engine rotational speed or drop in output torque after shifting, and good shift quality is obtained. Third, since the inertia phase is detected, engine torque reduction is started, and a torque return command is given near the end of the inertia phase, the timing of engine torque control is controlled by a timer control from a shift command or shift judgment. There is no problem with shifting due to timing discrepancies, as would be the case. In other words, it is a well-known fact for those skilled in the art that, in general, the return spring deflection time of a frictional engagement device varies greatly depending on various variations such as oil temperature, running conditions, and piston stroke. When control is performed by, for example, the timing of torque down control and the actual inertia phase may deviate. As a result, when the gear shift is faster than the engine torque control, the engine rotational speed Ne does not decrease easily even after entering the inertia phase as shown in FIG. 5(A), and the automatic This is a characteristic in which the output shaft torque of the transmission decreases and then returns to the normal level (dotted chain line). On the other hand, if the gear shift is slower than the engine torque control, the output torque will decrease before the gear shift starts, and the engine torque will be restored before the gear shift is completed, resulting in a very long engagement time and the failure of the friction engagement device. However, in this embodiment, the detection of the inertia phase is used as a condition for reducing the engine torque, so that the above-mentioned problem does not occur. Furthermore, if the engine torque return speed is not appropriate, for example, as shown in FIG. 5(B), if the torque return time To is short, the shift time will become longer and the durability of the friction engagement device will deteriorate. (dot-dash line), or conversely, the recovery time T
If o is too long, problems such as a drop in the output shaft torque of the automatic transmission (solid line) will occur. However, in this embodiment, since To is determined according to the type of shift, throttle opening, and shift pattern, extremely good shift characteristics can be obtained. Furthermore, if there is a large change in engine load (for example, throttle opening) during gear shifting, if the engine torque is not corrected to an amount corresponding to the engine load, for example, as shown in FIG. 5(C), When the engine load increases, a problem arises in that the shift time becomes longer and the durability of the frictional engagement device deteriorates. In this example,
This problem can be avoided because the amount of torque down and the speed of recovery are variable in accordance with changes in engine load. Furthermore, in the embodiment described above, since the detection method for detecting the start of the inertia phase is changed depending on whether the lock-up clutch 73 is in an engaged state or a disengaged state, it is possible to detect the start of the inertia phase regardless of the state of the lock-up clutch 73. The start of the inertia phase can always be accurately detected. In the above embodiment, the throttle opening degree is used as a representative engine load, but the present invention is not limited to this. For example, the output shaft torque of the engine is detected by a torque sensor, and this is used as the engine load. You may represent them.

【Effect of the invention】

As explained above, according to the present invention, regardless of the state of the lock-up clutch, it is possible to always obtain shift transient characteristics in which the shift shock is small and the shift time is short, while maintaining a good driving feeling. An excellent effect can be obtained in that the durability of the frictional engagement device can be improved.

[Brief explanation of the drawing]

The first factor is a flowchart showing the main structure of the present invention, and FIG.
A control timing diagram for explaining the operation of the embodiment of the present invention, FIG. 3 is a diagram showing a selection map of torque return speed in a normal pattern, FIGS. 4 and 5 (A) to (C) ) is a shift transient characteristic diagram comparing cases where each control timing or control weight is not optimal and when it is optimal, and FIG. 6 is an intake air amount sensing type to which the above embodiment is applied. FIG. 7 is a block diagram extracting the input/output relationship between the engine and the automatic transmission. 73...Lock-up clutch 102...Throttle sensor (engine load sensor)
108... Crank angle sensor (engine rotation speed sensor), 110... Vehicle speed sensor, 113... Transmission hydraulic oil temperature sensor, Ne... Engine rotation speed, No... Output shaft rotation speed, I L: Gear ratio before shifting. Figure 1

Claims (1)

[Claims] (1) By changing engine torque during gear shifting,
A shift control method for an automatic transmission with a lock-up clutch configured to maintain good shift characteristics includes a step of detecting whether or not the lock-up clutch is in an engaged state at the time of a shift determination; a step of detecting an output shaft rotational speed of an automatic transmission; and a step of detecting an output shaft rotational speed of an automatic transmission; The change of the engine torque is started by detecting that the rotation speed has become smaller than the rotation speed obtained from the product of the output shaft rotation speed, and when the lock-up clutch is in a disengaged state, Shift control for an automatic transmission with a lock-up clutch, comprising: a step of starting a change in the engine torque by detecting that the engine rotation speed has become smaller than a previously detected engine rotation speed; Method.