JPH0543528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a downshift control device for a vehicle automatic transmission configured to maintain good gear shifting characteristics by changing engine torque during gear shifting. Regarding.

[Conventional technology]

A gear transmission mechanism and a plurality of frictional engagement devices are provided, and engagement of the frictional engagement devices is selectively switched by operating a hydraulic control device, and any one of the plurality of gears is set. Automatic transmissions for vehicles configured to achieve 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 that detects the throttle opening, which is considered to reflect the engine load. The frictional engagement device is equipped with a sensor so that 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 the throttle opening.

By the way, in the automatic transmission for a vehicle as described above, an automatic transmission and an engine that change the engine torque during gear shifting to obtain good shifting characteristics and ensure and improve the durability of the frictional engagement device are proposed. Various integrated control methods have been proposed (for example, Japanese Patent Laid-Open Nos. 55-69738 and 58-77138). In other words, this integrated control changes the amount of torque transmitted from the engine during gear shifting, and controls the energy absorption of each member of the automatic transmission or the frictional engagement device that brakes these members, thereby achieving a short and small gear shifting shock. This is intended to provide the driver with a good shift feel by completing the gear shift, and to improve the durability of each frictional engagement device.

[Problem to be solved by the invention]

However, the above control was performed using a timer, etc., which started from the time of determining a gear shift, etc.
In reality, there are only a few cases where they can be adapted to the actual system as is, and the control accuracy cannot be said to be very good.

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 throughout the entire range of each transmission diagram, when and how to reduce engine torque must be clearly stipulated. It has to be something. This is because, depending on how you reduce the torque of the engine, a large shift shock may occur, impairing good driving sensation, or the shift time may become longer, reducing the durability of the friction engagement device. This is because it may get worse.

In particular, regarding changing engine torque during downshifting, there have been no effective materials disclosing this method.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and in particular clearly defines a method for controlling engine torque reduction during downshifts, and provides an automatic transmission for vehicles that can perform good downshifts. An object of the present invention is to provide a downshift control device.

[Means to solve the problem]

As summarized in FIG. 1, the present invention provides a downshift control device for a vehicle automatic transmission that is configured to maintain good shifting characteristics by reducing engine torque during a downshift. In order to detect the starting point for restoring engine torque reduction control, means for detecting the rotational speed of a rotating member whose rotational speed changes due to a downshift, and by detecting the rotational speed, the downshift reaches near its end time. a means for detecting whether or not the downshift has been completed; a means for detecting the elapsed time since it was detected that the downshift has been completed; and a means for detecting the elapsed time since it was detected that the downshift has been completed; The above-mentioned object is achieved by including means for setting the time when the engine torque is reduced as a starting point for restoring the engine torque reduction control.

Further, the above object is achieved by changing the predetermined timing depending on at least one of the type of downshift and the engine load.

[Effect]

The present invention first detects the rotational speed of a member of the automatic transmission during downshifting in order to reduce the engine torque when a gearshift decision is made to downshift, and by detecting the rotational speed,
start detecting the elapsed time after the downshift is detected to have reached its termination neighborhood;
By detecting the elapsed time, it is decided that the restoration of engine torque reduction control is started when it is determined that the predetermined time after the end of the downshift has been reached, thereby effectively suppressing the shift shock during the downshift. I can do it.

That is, the reason why a shock occurs due to a downshift is that when the rotating members are synchronized, the engine output is suddenly transmitted to the output shaft, resulting in strong torsional vibrations occurring in the power transmission system. Therefore,
As shown in FIG. 2, the reduction in engine torque begins immediately before the end of the downshift, and must continue for some time even after the downshift ends (after the rotating members are synchronized).

However, after the rotating members are synchronized,
As is clear from FIG. 2, the rotational speed of the rotating member hardly changes, and therefore, if the return point is determined based on a change in the rotational speed, it is inevitable that the detection error will increase.

In the present invention, the timing for returning the engine torque reduction control is determined by a timer from the time when the changing state of the rotating member is detected immediately before synchronization, so that the engine torque can be reduced to the minimum necessary amount with very high accuracy. .

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 3 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 sequence. This air is mixed with fuel injected from the injector 22 near the intake port 20, and
Further, the combustion chamber 26A of the engine body 26 via 4
sent to. Exhaust gas generated as a result of combustion of the air-fuel mixture in the combustion chamber 26A passes through the exhaust valve 2.
8, exhaust port 30, exhaust manifold 32 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 in the collecting part of the exhaust manifold 32. An O ₂ sensor 106 is provided. Furthermore, the distributor 38 having a shaft rotated by the crankshaft of the engine body 26 is provided with a crank angle sensor 108 for detecting a crank angle from the rotation of the shaft. The automatic transmission A/T also includes a vehicle speed sensor 1 for detecting vehicle speed from the rotational speed of its output shaft.
00, a shift position sensor 112 for detecting the shift position, and a hydraulic oil temperature sensor 113 for detecting the hydraulic oil temperature.

Each of these sensors 100, 102, 104, 1
The outputs of 06, 108, 110, 112, and 113 are from the engine computer (hereinafter referred to as ECU).
40 is input. The ECU 40 calculates the fuel injection amount using input signals from each sensor as parameters, and controls the injector 22 to inject fuel for a predetermined time corresponding to the fuel injection amount.

Note that an idle rotation control valve (ISCV) 42 is provided in the circuit that communicates the upstream side of the throttle valve 14 and the surge tank 16, and the ECU 40
The idle rotation speed is controlled by a signal from the engine.

As shown in detail in FIG. 4, the ECU 40
A central processing unit (CPU) 40A consisting of a microprocessor, a memory 40B for storing control programs and various data, and analog signals from the intake temperature sensor 100, water temperature sensor 104, transmission hydraulic oil temperature sensor 113, etc. An analog-to-digital converter (A/D converter) 40C having a multiplexer function for converting a signal into a digital signal and receiving the signal, and the throttle sensor 10
2, O ₂ sensor 106, crank angle sensor 108,
Vehicle speed sensor 110, shift position sensor 11
2, etc., and an input interface circuit 40D for directly taking in the output from the CPU 40A, and an ignition signal to the ignition coil 44, a fuel injection signal to the injector 22, and an idle signal to the ISCV 42 according to the arithmetic processing results of the CPU 40A. rotation control signal, and
The output interface circuit 40E is configured to output a signal to the ECT computer 50 for the automatic transmission A/T.

On the other hand, the ECT computer 50 includes a central processing unit (CPU) 5 consisting of a microprocessor.
0A, a memory 50B for storing control programs and various data, etc., and a throttle sensor 10.
2. An input interface circuit 50D for inputting outputs from the vehicle speed sensor 110, shift position sensor 112, pattern select switch 120, brake lamp switch 122, cruise control switch 124, and overdrive switch 126; It is comprised of an output interface circuit 50E for outputting control signals to solenoids S ₁ , S ₂ , and S ₃ of the automatic transmission A/T according to the results of calculation processing.

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 S2. A lock-up clutch control valve 64 is actuated by a solenoid _S3 , and a shift valve 6
1 and 62 control a 3rd speed section unit 71 for obtaining a gear ratio configuration of 1st to 3rd speeds, and a shift valve 63 controls an overdrive unit 72 for obtaining an overdrive gear ratio. The lock-up clutch 73, which mechanically directly connects the input and output sides of the torque converter, is controlled by the lock-up clutch control valve 64.

Also, in this ECU40, crank angle sensor 1
Utilizing the fact that the reciprocal of the time interval of the signal every 30 degrees of crank angle output from the crank angle sensor 108 is proportional to the engine rotation speed, the engine rotation speed is calculated based on the output signal from the crank angle sensor 108. I'm looking for.

Furthermore, this ECU 40 is an ECT computer 5
0 shift information (shift judgment, shift command, lock-up clutch engagement permission, etc.), executes engine torque down control and uses this control information.
Output 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 amount and timing of engine torque reduction. However, in the present invention, the number of control devices or their control areas It is not limited to.

FIG. 2 shows an embodiment of the present invention in more detail.

Figure 2 shows that a gear shift decision to perform a power-on downshift (a downshift with the accelerator depressed) was issued, and the lock-up clutch was in an engaged state when the gear shift decision was made. An example case is shown.

Here, whether or not the power is ON is determined depending on whether or not the throttle opening degree θ is larger than the set value θ _Z. The value of θ _Z is set differently in advance for each gear shift.

First, at point A, a shift decision is made in accordance with the vehicle speed and throttle opening (engine load).

At the same time as this shift judgment is made, a command to release the lock-up clutch is issued. Further, a shift command is issued after T ₁ sec from the shift determination. Timer T ₁
The purpose of providing this 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.

Along with this shift command, the engine rotation speed Ne and the output shaft rotation speed N ₀ of the automatic transmission are monitored to detect the member rotation speed change section (hereinafter referred to as the inertia phase), and the output shaft rotation speed N ₀ is monitored.
and low gear ratio I _L to turbine synchronous rotation speed N _T2
is calculated, and the time point (Ne ₃ ) when the engine rotation speed Ne which is lower by a constant N ₂ than N _T2 is reached is determined to be near the end of the inertia phase. Here, the constant N ₂ is a value preset according to the throttle opening θ _A and the type of gear change at that time. At the same time as the end of the inertia phase is detected, a command to reduce the engine torque is issued (point F).

The speed of engine torque down is done as fast as possible.

The amount of engine torque reduction uses a value selected from a preset map according to the throttle opening θ _D at the time of the engine torque reduction command, the type of gear change, or the vehicle speed. Considering vehicle speed,
This is because power ON downshifts almost always cross the shift line vertically. Furthermore, if there is a change in the throttle opening (θ _D →θ _F ), the corresponding value is successively corrected.

The restoration of the engine torque down starts from point G after T ₄ sec from the time of the torque down command (point F). This time _T4 is a value that is preset according to the throttle opening _θD and the type of shift at the time of the torque down command. Further, if the throttle opening changes thereafter (θ _D →θ _E ), the value is corrected to a corresponding value.

The speed at which the engine torque is restored is gradually increased over T ₀ sec from the engine torque restoration command. This T ₀ is a value set in advance according to the throttle opening degree θ _F and the type of gear change at the time of the engine torque return command (point G).

After the return of the engine torque is completed, a lock-up clutch engagement permission command is issued T ₃ sec after the shift command.

When a shift decision is made to perform a power-on downshift, and the lock-up clutch is in the released state when the shift decision is made, the shift command timing will be changed from the time when the lock-up clutch was released. It can be done after T ₁ sec. Therefore, if the lock-up clutch has been in the released state for at least T ₁ sec before the shift decision, an immediate shift command is issued along with the shift decision. As a result, the overall shift time can be shortened.

In the above embodiments, the engine load is represented by the throttle opening, but the present invention is not limited to this; for example, the output shaft torque of the engine is detected by a torque sensor,
This may be represented as the engine load.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain shift transient characteristics that can reduce the shift shock and shorten the shift time when a downshift is performed, and reduce friction while maintaining a good driving feeling. An excellent effect can be obtained in that the durability of the engagement device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main structure of the present invention, FIG. 2 is a control timing diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing a control timing chart to which the above embodiment is applied.
FIG. 4 is an overall schematic diagram of an automatic transmission combined with an electronic fuel injection engine for an automobile that senses the amount of intake air. FIG. 4 is a block diagram extracting the input/output relationship between the engine and the automatic transmission. 102...Throttle sensor (engine load sensor), 108...Crank angle sensor (engine rotation speed sensor), 110...Vehicle speed sensor, 11
3...Transmission hydraulic oil temperature sensor, Ne...engine rotation speed, P...oil pressure.

Claims (1)

[Claims] 1. In a downshift control device for a vehicle automatic transmission configured to maintain good shift characteristics by reducing engine torque during a downshift, the engine torque reduction control is restored. In order to detect the starting point, means for detecting the rotational speed of the rotating member whose rotational speed changes due to the downshift; and means for detecting whether the downshift has reached near its end time by detecting the rotational speed. and a means for detecting the elapsed time since it was detected that the end time has been reached; and a means for detecting the time when it is determined that the elapsed time has reached a predetermined time after the end of the downshift.
A downshift control device for an automatic transmission for a vehicle, comprising: means for using engine torque reduction control as a starting point for recovery; and a downshift control device for a vehicle automatic transmission. 2. The downshift control device for a vehicle automatic transmission according to claim 1, wherein the predetermined timing is changed depending on at least one of the type of downshift and the engine load.