JPH0790733B2 - Downshift control device for vehicle automatic transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an improvement in a downshift control device for an automatic transmission for a vehicle, which is configured to maintain good gear shifting characteristics by reducing engine torque during a downshift.

[Prior art]

An automatic transmission for a vehicle, which is configured to selectively switch the engagement state of a friction engagement device by operating a hydraulic control device to achieve any one of a plurality of shift speeds, has already been widely used. Are known. Further, in such an automatic transmission for a vehicle, various automatic transmissions and an integrated control device for an engine which change the engine torque at the time of shifting have been proposed (for example, Japanese Patent Application No. 59-234466). When the engine torque is changed during gear shifting, the energy absorbed by each member of the automatic transmission or the friction engagement device that controls these can be controlled, and the gear shifting can be completed in a short time and with a small gear shift. it can. As a result, it is possible to give the driver a good feeling of shifting and improve the durability of the friction engagement device.

[Problems to be Solved by the Invention]

However, in order to always ensure good gear shifting characteristics obtained by changing the engine torque over the entire area of each shift diagram, it was clearly specified when and how the engine torque was changed. It must be a thing. This is because, depending on how the engine torque is changed, a large gear shift shock may occur, which hinders a good driving feeling, or the gear shift time may become long and the friction engagement device may become less durable. It will worsen. In this regard, the applicant clearly specified in Japanese Patent Application No. 59-234466 the engine torque change control method, and can effectively perform the engine torque change control. Was disclosed (unknown). That is, in engine torque control during downshifting, reduction of engine torque is started near the end of gear shifting, and this reduction continues for a while even after gear shifting is completed (after synchronization), and then gradually returns. It should be disclosed. In the same application, when this control is specifically executed, it is specifically to accurately detect the return time "a point in time after the shift is completed".
In view of the fact that it is difficult in reality, a method of rationally combining the method of monitoring the rotating member and the method of the timer is also disclosed. However, for example, when the engine torque is reduced by retarding the ignition timing at the time of downshifting, there is a problem that good gear shifting characteristics may not be obtained even by the above disclosed technology. It was When the engine torque is reduced by the ignition retard, the retard amount (engine torque reduction amount) set in advance is searched according to the throttle opening at that time, the type of shift, and the like. However,
On the engine side, the ignition timing is in a certain range to prevent pre-ignition,
For example, since it is specified by BTDC 5 to 47 ° CA, the searched retard amount may not always be accepted.
That is, generally, the ignition timing or the regulation of the ignition timing (base advance angle) is set for each value of the engine speed and the engine load (for example, throttle opening). Therefore, the amount of retardation that can be executed is limited to within (base advance angle −5 °). As a result, even with the same type of downshift, the retard amount is also suppressed in the case of a shift from an engine speed where a certain base advance angle is set to a low value, so the timing of change (especially If the return timing) is not properly corrected, a sufficient torque change amount cannot be obtained, and a problem that good gear shifting characteristics cannot be obtained occurs.

[Object of the Invention]

The present invention has been made in view of the above-mentioned problems, and is an automatic vehicular vehicle that is adapted to maximize the improvement of the shift characteristics by changing the torque regardless of the engine speed. An object of the present invention is to provide a downshift control device for a transmission.

[Means for Solving the Problems]

The present invention provides a downshift control device for an automatic transmission for a vehicle, which is configured to maintain good gear shifting characteristics by reducing engine torque during downshifting.
As shown in the outline of FIG. 1, a means for detecting the rotational speed of a rotating member whose rotational speed changes due to a downshift, and whether or not the downshift has reached the vicinity of its end timing by detecting the rotational speed. A means for detecting, a means for reducing the engine torque for a predetermined time determined by a timer after it has been detected that the time has come near the end time, a means for detecting the value of the engine speed, and a value for the engine speed. And a means for changing and setting the predetermined time depending on the above. The "engine speed value" in the present invention does not mean such a qualitative tendency such as an increase, a decrease, or a synchronization of the engine speed.
It means a concrete value itself such as m or 3000 rpm. Therefore, as a matter of course, this "engine speed value" can be replaced by another equivalent value. For example, if you know the type of gear (gear),
It is possible to substitute the value of the vehicle speed. When setting the torque reduction timing (predetermined time after shifting) depending on the engine speed value, it is possible to set a basic map and correct it according to the engine speed value. Alternatively, it may be directly set by a map or the like depending on the engine rotation speed from the beginning.

[Action]

The applicant has filed in Japanese Patent Application No. 59-234466 (not known)
It has been disclosed that the engine torque at the time of downshifting should be reduced from the vicinity of the end of the shift, and after the synchronization, this reduction should be slightly resumed and then restored. This is because the gear shift shock occurs during downshifting because the torque from the engine is rapidly transmitted to the output shaft side as if the step input was applied because the rotation speeds of the members are synchronized. This is because the output shaft torque overshoot or vibration is generated due to the twisting of the power transmission system. In the same application, "the time when a little has passed after the synchronization"
A rational method is also disclosed regarding how to specifically detect. Since this is an unknown method, its contents will be described. Generally, there are two methods for detecting a specific time related to a shift. One is a method using a timer based on a shift command or the like, and the other is a method of monitoring the actual rotation speed of the member. The timer method is inexpensive, but the accuracy is low, and it may not match the actual progress of the shift. On the other hand, the monitor method is expensive because it requires a sensor and it is also necessary to consider the file, but the accuracy is high. However, it is only until the shift is completed, that is, when the rotation speeds of the members are synchronized, that the monitoring of the rotation speed of the member provides highly accurate information regarding the specific time period related to the shift. If the member being monitored is the output shaft of the automatic transmission, basically only changes that depend on the vehicle speed will occur after synchronization, and there may be almost no changes depending on the road surface slope. It is extremely difficult to determine the later specific time. Further, when the member being monitored has the engine rotation speed, it may be strongly influenced by the accelerator work, and sometimes the behavior may be completely unpredictable. Therefore, for example, in the method of detecting the "start point of return" by monitoring the rotation speed of the member and detecting whether or not the rotation speed has become slightly higher than the synchronous rotation speed, it is not always possible to accurately and accurately determine the starting point. It is not possible to detect the return time. Therefore, in the above-mentioned prior application, in consideration of this point, first, by detecting the rotational speed of the member, the vicinity of the end of the gear shift is detected with high accuracy (because it is before synchronization, it can be detected with high accuracy), and then, The method of starting a timer is devised and disclosed. As a result, it is possible not to be affected by the length of the shift time and to "correctly detect the return time" so as to eliminate the influence of various unstable elements after the synchronization. The present invention is based on this previously unknown prior application technology, and further devised the following in setting the timer (predetermined time). This will be explained by taking as an example the case where a fourth down → first speed checkdown is performed from 40 km / h and 50 km / h. The shift transition characteristic at this time is as shown in FIGS. 6 (A) and 6 (B). As shown in FIG. 6 (A), the fourth from 50 km / h
Good gear shifting characteristics can be obtained from the first speed to the first speed down, but as shown in FIG. 7B, vibration occurs in the vehicle from the fourth speed to the first speed down from 40 km / h. The reason for this will be described with reference to FIG. 4th from 40km / h
In the case of the speed → the first speed kickdown, the engine speed value that causes the engine torque down is 3600 rpm, and the base advance angle of the ignition timing at this time is BTDC22 ° CA. This base advance angle is a value that is generally set by the computer for each engine rotation speed value and throttle opening. Further, it is assumed that the command value of the retard angle amount at this time is set to 24 ° CA for the purpose of reducing the engine torque by 50%. in this case,
On the engine side, for example, to prevent ignition, set the ignition timing.
Since the BTDC is specified at 5 to 47 ° CA, the actual retard amount is 24
-5 = 17 ° CA, and the torque reduction rate is only 28%. The engine torque at this time is 177 N · m. Similarly, at the time of a kickdown from 50 km / h, 134 N ・ m
Becomes As described above, if the torque reduction recovery timing or the recovery speed is set to be the same even though the torque reduction of the intended amount is not performed, the ignition timing that should originally be the two-dot chain line in FIG. The solid line causes the output shaft torque to oscillate and hinder a good shift feeling. In the present invention,
In such a case, the vibration of the output shaft torque can be suppressed by changing the predetermined time during which the engine torque is reduced (including the concept of the return timing and the return speed) as shown by the broken line, and the shift characteristics are improved. It becomes possible. Now, the description has been given of the downshift from the fourth speed to the first speed, but the same applies to downshifting to another gear. The value of the engine rotation speed can be obtained based on the value of the vehicle speed and the type of shift. The value of the vehicle speed and the type of shift are always included as information when shifting. Therefore, especially when the computer controlling the automatic transmission and the computer controlling the engine are configured separately, it is useful to replace the value of the engine rotation speed with the value of the vehicle speed and the type of the speed change. There is a case.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is an overall schematic view of an automatic transmission combined with an intake air amount sensing type electronic fuel injection engine for an automobile to which the present invention is applied. The air sucked from the air cleaner 10 is sequentially sent to the air flow meter 12, the throttle valve 14, the surge tank 16, and the intake manifold 18. This air is mixed with fuel injected from the injector 22 near the intake port 20, and the intake valve
It is further sent to the combustion chamber 26A of the engine body 26 via 24. Exhaust gas generated as a result of combustion of the air-fuel mixture in the combustion chamber 26A is released to the atmosphere via the exhaust valve 28, the exhaust port 30, the exhaust manifold 32, and the exhaust pipe 34. The air flow meter 12 is provided with an intake air temperature sensor 100 for detecting the intake air temperature. The throttle valve 1
Reference numeral 4 rotates in conjunction with an accelerator pedal (not shown) provided in the driver's seat. The throttle valve 14 is provided with a throttle sensor 102 for detecting its opening. Further, the cylinder block 26B of the engine body 26 is provided with a water temperature sensor 104 for detecting the engine cooling water temperature, and at the gathering portion of the exhaust manifold 32, in order to detect the oxygen concentration in the gathering portion. O ₂ sensor 10
Six are provided. Further, the distributor 38 having a shaft rotated by the crank shaft of the engine body 26 is provided with a crank angle sensor 108 for detecting a crank angle from the rotation of the shaft. Also, automatic transmission A / T
Includes a vehicle speed sensor 100 for detecting the vehicle speed from the rotation speed of the output shaft, a shift position sensor 112 for detecting the shift position, and a hydraulic oil temperature sensor for detecting the hydraulic oil temperature. 113 is provided. Each of these sensors 100, 102, 104, 106, 108, 110, 11
The outputs of 2 and 113 are input to an engine computer (hereinafter referred to as ECU) 40. The ECU 40 calculates the fuel injection amount using the input signal from each sensor as a parameter, and controls the injector 22 so that the fuel is injected for a predetermined time corresponding to the fuel injection amount. An idle rotation control valve (ISCV) 42 is provided in the circuit that connects the upstream of the throttle valve 14 and the surge tank 16, and the idle rotation speed is controlled by a signal from the ECU 40. There is. As shown in detail in FIG. 3, the ECU 40 includes a central processing unit (CPU) 40A composed of a microprocessor and a memory 40B for storing control programs and various data.
And an analog-digital converter (A / D converter) having a multiplexer function for converting the analog signals from the intake air temperature sensor 100, the water temperature sensor 104, the transmission hydraulic oil temperature sensor 113, etc. into a digital signal and fetching the digital signal. ) 40C, the throttle sensor 102, the O ₂ sensor 106, the crank angle sensor
108, a vehicle speed sensor 110, a shift position sensor 112, etc., an input interface circuit 40D for directly capturing the output, and an ignition signal to the ignition coil 44, an injector 22 according to the arithmetic processing result of the CPU 40A. And an output interface circuit 40E for outputting a signal to the ECT computer 50 for the automatic transmission A / T and a fuel injection signal to the ISCV 42. On the other hand, the ECT computer 50 includes a central processing unit (CPU) 50A composed of a microprocessor, a memory 50B for storing a control program and various data, a slot sensor 102, a vehicle speed sensor 110, a shift position sensor.
112, the pattern select switch 120, the brake lamp switch 122, the cruise control switch 124, and the input interface circuit 50D for inputting the output from the overdrive switch 126, and the automatic transmission according to the calculation processing result of the CPU 50A. A / T solenoid S ₁ ,
And an output Interferon chair circuit 50E for outputting a control signal to the S _2, S _3. The automatic transmission A / T includes a 2-3 shift valve 61 driven by the solenoid S ₁ , a 1-2 shift valve 62 and a 3-4 shift valve driven by the solenoid S ₂ .
63, a lockup clutch control valve 64 driven by the solenoid S ₃ is provided, and a shift valve 6
The first and second gears 62 and 63 control the third speed unit for obtaining the gear ratio configurations of the first to third speeds, and the shift valve 63 controls the overdrive unit for obtaining the overdrive gear ratio. The lockup clutch control valve 64 controls the lockup clutch mechanically directly connecting the input and output sides of the torque converter. Further, in the ECU 40, the fact that the reciprocal of the time interval of the signal output from the crank angle sensor 108 for every 30 ° of crank angle is proportional to the engine speed is used to output the signal from the crank angle sensor 108. Based on the calculation, the engine speed is calculated. Further, the ECU 40 is provided with shift information of the ECT computer 50 (shift determination, shift command, lockup clutch connection permission, etc.).
Receives the engine torque reduction control,
This control information is output to the ECT computer 50. Based on this information, the ECT computer 50 issues a lockup clutch release command and inspects whether or not the above-mentioned control is being performed reliably. In this embodiment, the ECU 40 and the ECT computer 50 are separated, and the engine torque reduction amount and timing are EC
Although the U40 determines and executes this, the present invention does not limit the shared area of the control device. Next, the operation of this embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 shows an example in which the gear shift judgment for performing the power-on downshift has been made, and the lockup clutch is in the engaged state when the gear shift judgment is made. Here, whether or not the power is turned on is determined based on whether or not the throttle opening θ is larger than the set value θ _z . The value of θ _z is set differently in advance for each type of shift. First, at point A, a shift determination is made according to the vehicle speed and the throttle opening (engine load). At the same time when this shift determination is issued, a release command for the lockup clutch is issued. Also, from the shift judgment, T ₁ sec
After that, a shift command is issued. The reason why the timer T _{1 is given} a grace is that the gear shift command is issued based on the last gear shift judgment when two or more gear shift judgments are made in a short time. Due to the existence of this timer T ₁ , for example, the fourth
It is possible to directly perform the downshift from the first speed to the first speed. The engine speed Ne for detecting the start timing of the engine torque change and the output shaft rotation speed N _{0 of} the automatic transmission are monitored together with this shift command, and the turbine speed is calculated from the output shaft rotation speed N ₀ and the low speed gear ratio I _L. calculate the synchronous rotational speed N _T2, the N _T2
When the shift has progressed to the time point (Ne ₃ ) at which the engine speed Ne has become lower by a constant N _2, it is determined that the shift has reached near the end, and this time point is determined as the start time of the engine torque. Here, the constant N ₂ is set according to the throttle opening θ _A , the type of gear shift, and the vehicle speed (specifically, the output shaft rotation speed N ₀ ). A specific example of this is shown in FIG. When the engine speed reaches Ne ₃ , the engine torque down start command is issued (F
point). The engine torque is reduced at the highest speed possible. As the engine torque reduction amount, a value selected from a map preset according to the throttle opening θ _D when the engine torque down command is issued, the type of gear shift, and the vehicle speed is used. The reason why the vehicle speed should be taken into consideration is that the power line is generally crossed vertically during a power-on downshift. Further, if there is a change in the throttle opening thereafter (θ _D → θ _F ), the corresponding values are sequentially corrected. The engine torque reduction is restored from the torque down command point (point F) by the timer T ₄ se.
It starts from point G after c. The timer T ₄ is a value preset according to the throttle opening θ _D at the torque down command point, the type of shift, and the vehicle speed (output shaft rotation speed N ₀ ). A specific example is shown in FIG. If the throttle opening changes thereafter (θ _D → θ _E ), the value is corrected to a corresponding value. The recovery speed of the engine torque is gradually increased from the engine torque recovery command over the timer T ₀ sec. This timer T ₀
Is a value preset according to the throttle opening θ _F when the engine torque is returned (point G), the type of gear shift, and the vehicle speed (N ₀ ). A specific example is shown in FIG. After return of the engine torque is completed, T ₃ se from shift command
After c, the lock up clutch engagement permission command is issued. The constant N ₂ and the timers T ₄ and T ₀ described above are set to the engine load (slottle opening), the type of shift, and the vehicle speed (output shaft rotation speed N ₀ ).
It is a feature of this embodiment that it is set according to The reason why the concept of shift type and vehicle speed is adopted instead of engine rotation speed is that the engine rotation speed can be obtained by knowing the shift type and vehicle speed, and accordingly, the base advance angle at that time, execution This is because it is possible to know the possible amount of retardation and the like, and also it is possible to finely set each numerical value such as N ₂ , T ₄ , and T _{0 according} to the type of shift. The “predetermined time” in the claims includes both the concepts of the timers T ₄ and T ₀ . In the case where the shift judgment for performing the power-on downshift is made and the lockup clutch is in the released state when the shift judgment is made, basically the same control as in FIG. 4 may be performed. However, the shift command timing is T ₁ from the time when the lockup clutch is released.
Can be after sec. Therefore, T ₁ sec
If the lockup clutch has been released from the above, the speed change command is immediately issued together with the speed change determination. As a result, the entire shift time can be shortened.

【The invention's effect】

As described above, according to the present invention, it is possible to accurately detect the engine torque return timing in engine torque control for downshifting, and the expected engine torque change amount is requested by the engine side. Even if it is not possible to realize from the above, it is possible to appropriately correct the return timing of torque reduction according to the engine speed at that time, and as a result, it is possible to always obtain good shift characteristics. Excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the gist of the present invention, and FIG. 2 is
An overall schematic view of an automatic transmission combined with an intake air amount sensing type electronic fuel injection engine for an automobile, to which an embodiment of an automatic transmission and engine integrated control device according to the present invention is applied, FIG. the automatic transmission and the block diagram shown by extracting input-output relationship of the engine, Fig. 4, the control timing diagram at the time of performing the above-described embodiment, Fig. 5, N _2,
Diagram showing examples of T ₄ and T ₀ maps, FIGS. 6 (A) and 6 (B)
Fig. 7 is a gear shift transient characteristic diagram for explaining the basic operation of the present invention. Fig. 7 compares various specifications when performing the 4th → 1st downshift from 50km / h and 40km / h. FIG. 102 …… Slottle sensor, 110 …… Vehicle speed sensor, Ne …… Engine speed, N ₀ …… Output shaft speed (vehicle speed).

Claims (1)

[Claims] 1. A downshift control device for a vehicular automatic transmission configured to maintain good gear shifting characteristics by reducing engine torque during a downshift. A means for detecting the rotational speed of the member, a means for detecting whether or not the downshift has reached near the end time by the detection of the rotational speed, and a timer for detecting that the downshift has reached near the end time. Therefore, there are provided means for reducing the engine torque for a predetermined time to be determined, means for detecting the value of the engine rotation speed, and means for changing / setting the predetermined time depending on the value of the engine rotation speed. A downshift control device for an automatic transmission for a vehicle, comprising: