JP2543402B2 - Upshift control device for automatic transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upshift control device for an automatic transmission configured to maintain good gear shifting characteristics by changing engine torque during upshift.

[Prior art]

A gear shift mechanism and a plurality of friction engagement devices are provided, and the engagement of the friction engagement devices is selectively switched by operating a hydraulic control device. Vehicle automatic transmissions configured to be achieved are already widely known. Such an automatic transmission for a vehicle is generally a shift lever operated by a driver, a vehicle speed sensor for detecting a vehicle speed, and a throttle for detecting a throttle opening which is considered to reflect an engine load. A sensor is provided, and the engagement state of the friction 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 vehicles as described above,
Various automatic transmission and engine integrated control methods have been proposed in which the engine torque is changed during gear shifting (especially during upshifting) to obtain good gear shifting characteristics, and the durability and durability of the friction engagement device are secured and improved. (For example, JP-A-55-46
095, 55-69738, 58-77138, 58-180768, 60
−263774). That is, this integrated control changes the amount of torque transmitted from the engine at the time of gear shift, and controls the energy absorption by each member of the automatic transmission or the friction engagement device that brakes these members, thereby achieving a small gear shift in a short time. The gear shift is completed by shock so as to give the driver a good feeling of gear shift and to improve the durability of each friction engagement device.

[Problems to be Solved by the Invention]

However, the above-mentioned control is performed by using a timer or the like that starts from the time of gear shift determination, but in reality, there are few cases where they can be directly adapted to the actual system, and the control accuracy is not very good. The reality is that I cannot say that. It is considered that there is nothing that clearly defines how to reduce the engine torque. However,
In order to always ensure good gear shifting characteristics obtained by reducing the engine torque over the entire area of each gear shift diagram,
When and how to reduce the engine torque must be clearly defined. Because, how to reduce the torque of the engine depends on
On the contrary, a large gear shift shock may occur to impair a good driving feeling, or the gear shift time may become long and the durability of the friction engagement device may deteriorate. In this regard, in JP-A-55-69738, the start timing of the engine torque change is determined from the change state of the engine rotational speed so that the engine torque control can be performed in synchronization with the actual shift state of the transmission as much as possible. The disclosed technology is disclosed. However, the above-mentioned JP-A-55-69738 prorates the engine rotation speed, which is the base point of the engine torque change timing, from the engine rotation speed at the time of the gear shift command and the engine rotation speed at the end of the gear shift (when the synchronous rotation is reached). However, there is a problem that it is not always possible to obtain good gear shifting characteristics. That is, according to the research conducted by the applicant, the best result is obtained by starting the change of the engine torque with the start of the inertia phase. The inertia phase refers to a period (substantial shift period) in which each rotating member causes a change in rotation speed due to a shift. Even if the gear shift command is issued, the rotation speed of each rotary member does not change immediately, but after a while, the rotation speed finally starts changing. The time from the shift command to the start of the rotation speed change (the start of the inertia phase) changes depending on the oil temperature, the running condition, the piston stroke of the friction engagement device (particularly the idling distance), and the like.
That is, for example, if the type of speed change (type of friction engagement device to be engaged) changes, and if the engine load or the oil temperature changes, the generated oil temperature also changes, which causes a change. Moreover, since the devices vary from one device to another, each device actually has a different value. However, the technique disclosed in JP-A-55-69738 has no concept of detecting the start of the inertia phase, and as a result, the engine torque is changed before the start of the inertia phase. There is a problem in that the output shaft torque may be reduced, or a sudden change in the output shaft torque immediately after the start of the inertia phase may not be properly suppressed. The present invention has been made in view of such a conventional problem, and makes it possible to accurately determine the start timing of engine torque change based on the actual rotational speed change state of the rotating member, and The change timing is determined based on the time point when the shift enters the inertia phase so that it is completely synchronized with the shift state that is currently in progress, thus preventing erroneous detection in timing detection and at low cost. Moreover, it is an object of the present invention to provide an upshift control device for an automatic transmission, which is capable of performing good shift control in all shifts.

[Means for Solving the Problems]

As shown in FIG. 1 of the gist of the present invention, in an upshift control device for an automatic transmission configured to maintain good gear shifting characteristics by reducing the engine torque during upshifting, the engine torque In order to detect the start timing of the reduction control, means for detecting the input shaft rotation speed of the automatic transmission, means for detecting the output shaft rotation speed of the automatic transmission, and the output shaft rotation speed and the automatic transmission Means for obtaining a reference value related to the start of the inertia phase based on the product with the gear ratio before the upshift, and means for detecting whether or not the input shaft rotation speed of the automatic transmission is below the reference value. The above object is achieved by setting the start timing of the engine torque reduction control as the starting point when it is detected that the input shaft rotation speed of the automatic transmission falls below the reference value. One in which was achieved.

[Action]

In the present invention, the timing of engine torque change is determined by determining the start of the inertia phase based on the actual shift progress state (not the timer), that is, the change state of the input shaft rotation speed of the automatic transmission. I am trying. As a result, it becomes possible to execute the engine torque change at a timing that reflects the current shift state. The "input shaft rotation speed of the automatic transmission" here means the "input shaft rotation speed of the actual transmission mechanism of the automatic transmission".
That is, it means the output shaft rotational speed (turbine rotational speed) of the torque converter attached to the front stage of the automatic transmission. More specifically, in the present invention, when detecting the start of this inertia phase, the inertia is calculated based on the product (N ₀ × I _L ) of the output shaft rotation speed N ₀ and the gear ratio I _L before the shift. Determine the reference value (N ₀ × I _L −ΔN: ΔN is a constant) found in relation to the start of the phase, and determine whether the input shaft rotation speed _{NT of} the automatic transmission is lower than this reference value. However, when it is judged that it has fallen below, it is judged that the inertia phase has started for the first time. As a result, the start of the inertia phase can be determined at an early stage and very accurately, and the engine torque can be reduced appropriately. The reference value (N ₀ × I _L −ΔN) is specifically N ₀ ×
I _L itself (that is, ΔN = 0) is the most direct value. However, since the detected value always includes an error, when actually implementing the present invention, the reference value is (ΔN) in order to prevent the above relationship from being established from the beginning due to the error. Would be set to N ₀ × I _L −ΔN.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 6 is an overall schematic view of an automatic transmission to which the present invention is applied and which is combined with an intake air amount sensing type electronic fuel injection engine for an automobile. The air sucked from the air cleaner 10 is sequentially sent to an air flow meter 12, a throttle valve 14, a surge tank 16, and an intake manifold 18. 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. Exhaust gas generated as a result of combustion of the air-fuel mixture in the combustion chamber 26A is released to the atmosphere via an exhaust valve 28, an exhaust port 30, an exhaust manifold 32, and an 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 14 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
6 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, 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 as to inject the fuel for a predetermined time corresponding to the fuel injection amount. An idle rotation control valve (ISCV) 42 is provided in a circuit that connects the upstream of the throttle valve 14 to the surge tank 16, and the idle rotation speed is controlled by a signal from the ECU 40. I have. As shown in detail in FIG. 7, the ECU 40 includes a central processing unit (CPU) 40A composed of a microprocessor and a memory 40 for storing control programs and various data.
And an analog-digital converter (A / D) having a multiplexer function for converting analog signals from the intake air temperature sensor 100, the water temperature sensor 104, the transmission operating oil temperature sensor 113, and the like into digital signals and taking in the digital signals. converter) and 40C, the Surotsutorusensa 102, O ₂ sensor 106, a crank angle sensor 108, vehicle speed sensor 110, a shift positive Chillon sensor 112,
Input interface circuit 40D for directly capturing the output from the etc., according to the arithmetic processing result of the CPU 40A, ignition signal to the ignition coil 44, fuel injection signal to the injector 22, idle rotation control to the ISCV42 Signal and
It is composed of an output interface circuit 40E for outputting 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) 50A composed of a microprocessor, a memory 50B for storing a control program and various data, a throttle sensor 102, a vehicle speed sensor 110, and a shift position sensor 112. An input interface circuit 50D for inputting outputs from the pattern select switch 120, the brake lamp switch 122, the cruise control switch 124, and the overdrive switch 126, and the automatic transmission A in accordance with the arithmetic processing result of the CPU 50A. / T solenoids S ₁ , S
And an output Interferon chair circuit 50E for outputting a control signal to the _2, S _3. Automatic transmission A / T, the solenoid S 2-3 shift valve 61 is by connexion driven to _1, the solenoid S 1-2 shift is by connexion driven _second valve 62 and 3-4 shift valve 63, the It includes a b look up class Tutsi control valve 64 which is by connexion driving the solenoid S _3, shift valve
61 and 62 control the third speed unit for obtaining the first to third gear ratio configurations, and the shift valve 63 controls the overdrive unit for obtaining the overdrive gear ratio. The lock-up clutch control valve 64 controls the lock-up clutch that mechanically directly connects the input / output side of the torque converter, that is, the "engine" and the "input shaft of the automatic transmission". 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 receives the shift information (shift determination, shift command, lockup clutch engagement permission, etc.) of the ECT computer 50, executes engine torque down control, and outputs this control information to the ECT computer 50. ECT
Based on this information, the computer 50 issues a lockup clutch release command, and inspects whether or not the above control is being performed reliably. In this embodiment, the ECU 40 and the ECT computer 50 are separate bodies, 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 sharing region is used. Is not limited. Next, with reference to FIGS. 2 and 3, an embodiment of a control method when a shift judgment for making a power-on upshift (upshift with the accelerator depressed) will be described. In this embodiment, the engine speed Ne is used as a means for detecting the progress state of the shift for cost reduction, and the lockup clutch is determined when the shift is determined.
The present invention is intended to be applied on condition that it is ON. As is well known, the engine rotation speed Ne is the same as the input shaft rotation speed (turbine rotation speed) N _T when the lockup clutch is turned on. When the dedicated N _T sensor is used, the present invention can be applied even when the lockup clutch is OFF. First, at the point A in the figure, a shift determination is made according to the vehicle speed and the throttle opening (engine load), and after a time corresponding to the timer T _{1 has} elapsed, a shift command is issued at the point B. The timer T _{1 is given} a grace period in order to issue a gear shift command based on the last gear shift determination when two or more gear shift determinations are made in a short time. Output shaft rotation speed N ₀ and engine rotation speed Ne (= N _T ) of the automatic transmission are detected to detect the progress of shifting after the gearshift command.
And start monitoring. In this embodiment, the product (N ₀ × I _L ) of the output shaft rotation speed N ₀ and the low-speed gear ratio (gear ratio before upshift) I _L is first obtained, and ΔN (constant) is subtracted from this product Ne ₁ (= N ₀ × I _L −ΔN) is obtained as a reference value related to the inertia phase, and the engine speed Ne (= N _T ) is below this reference value Ne ₁ n ₁ times in succession. It is determined that the inertia phase has started (point C in Figure 2). Note that, as described above, N ₀ × I _L itself is the most direct value as the reference value Ne ₁ , as described above. However,
Since the detected value always includes an error, in order to prevent the above relationship from being established from the beginning due to the error, specifically, the reference value is N ₀ × I _L −ΔN (ΔN is constant)
It is said that. In addition, n ₁ is a constant for preventing a detection error. This n ₁ may be changed according to the throttle opening, the type of gear shift, and the like. In this way, by confirming that Ne <Ne ₁ is satisfied for n ₁ times in succession, Ne <Temporarily due to erroneous detection of the engine speed sensor or pulsation of the engine speed (turbine speed) itself, Ne < It becomes possible to prevent Ne _{1 from} being established and the torque change being executed too early. Simultaneously with the detection of the start time of the inertia phase, a lock-up clutch release command is issued and an engine torque-down command is issued. The torque of the engine is reduced as fast as possible. The amount of engine torque down is determined by the engine load (slottle opening), gear shift,
It is determined by selecting a corresponding value from preset maps depending on the temperature of the hydraulic oil and the shift pattern. The operation oil temperature is detected in consideration of the fact that when the operation oil temperature rises, the oil pressure of the friction engagement device generally tends to decrease due to an increase in pressure leakage inside the control device. Therefore, it is desirable to make a correction to increase the torque reduction amount of the engine as the hydraulic oil temperature increases. If there is a change in the throttle opening during gear shifting (θ _A →
θ _B ), and the value is sequentially corrected to a value corresponding to the opening degree θ _B. In this case, when the throttle opening becomes larger, the torque reduction amount of the engine is also corrected to be larger. The engine torque return command timing is performed near the end of the inertia phase. In this embodiment, the output shaft rotational speed N ₀ of the automatic transmission and the high speed gear ratio I _{H are used} to determine the turbine synchronous speed.
Calculate N _T1 and increase the engine speed Ne (turbine speed N _T ) to a speed higher by a constant N ₁ than this turbine synchronous speed N _T1.
When is reached (Ne ₂ ), it is determined to be near the end of the inertia phase (point D). That is, N ₀ × I _H +
This is when N ₁ ≧ Ne holds. Here, the constant N ₁ corresponds to a correction term for more accurately determining the end of the inertia phase according to the state of the automatic transmission, and includes the throttle opening θ _C at the time of calculation, the type of shift, and the shift. A value preset in accordance with the pattern is used. The torque recovery of the engine is gradually performed for T ₀ sec from the time (D point) when the command for the engine torque recovery is issued. As the time T _0, for example, as shown in FIG. 3, a preset value corresponding to the throttle opening θ _C at the time of the return command, the type of shift, and the shift pattern is used. Note that FIG. 3 shows an example of a map composed of each throttle opening θ ₀ ... θ ₇ and the type of shift when the shift pattern is N (normal pattern), and the throttle opening becomes large. Accordingly, T _{0 is set} to be larger, and T ₀ is set to be smaller when the type of shift is a higher gear. Also, if the shift pattern is P (power pattern), for example, each value in the normal pattern
The value is multiplied by 1.1, and in the case of E (economy pattern), the corresponding value of the normal pattern is set to be the value multiplied by 0.9. However, the same map as N (normal pattern) may be preset for each T ₀ for each shift pattern. Further, in FIG. 3, θ ₀ ... θ ₇ may be obtained by dividing the throttle from fully closed to fully open by a non-linear size. After return of the engine torque is completed at point E in FIG, engagement permission command due connexion b look up class Tutsi to T ₃ of the timer is issued from the shift command (F point). This timer T ₃
Is preset to a value such that the lock-up clutch engagement permission command is issued after the completion of the engine torque recovery. If the lockup clutch is OFF at the time of gear shift determination, the engine and the automatic transmission are not in direct connection, so as a means for detecting the start of the inertia phase,
Since the above method cannot be taken, for example, by monitoring the engine speed Ne after the gear shift command, Ne _i <Ne _i-1 is n ₂
Judgment will be made when there are consecutive times. Here, n ₂ is a constant for preventing the detection error, and its meaning is the above-mentioned Ne.
<It is the same as confirming the establishment of Ne ₁ n ₁ times in succession. That is, by confirming that Ne _i <Ne _i-1 is established n ₂ times in succession, it is possible to accurately detect that the engine speed has begun to decrease. When the lockup clutch is OFF, the engine rotation speed pulsates particularly greatly, so this determination for consecutive n ₂ times is more significant. It should be noted that this n ₂ may be changed according to the throttle opening, the type of speed, and the like. Others are the same as those described above, and thus redundant description will be omitted. As described above, in the above embodiment, the conditions for starting the engine torque are changed depending on the engagement state of the lockup clutch, and the engine torque of the engine torque is changed when these conditions continue for n ₁ times and n ₂ times. Since it is determined to be the true start time, it is possible to prevent a detection error in a broad sense. Also, the installation of (expensive) dedicated _NT sensor can be omitted, and the cost is reduced accordingly. As described above, if the dedicated _NT sensor (input shaft rotation speed sensor of the automatic transmission) can be provided, the present invention can be implemented regardless of whether the lockup clutch is ON or OFF. It is not necessary to divide the cases. By the way, in the above-described embodiment, the engine torque is recovered only by satisfying N ₀ × I _H + N ₁ ≧ Ne once. This is because, as is clear from the fact that the engine torque is gradually restored, a slight timing error has little influence on the engine torque restoration. However, it is obvious that the condition for returning the engine torque may be determined to be the starting point of the returning timing when the condition is satisfied n ₃ times in succession. Next, the basic shift transient characteristics in the control of the embodiment of the present invention (FIGS. 2 and 3) will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, in this embodiment, after the gear shift command, the engine rotation speed Ne (= turbine rotation speed N _T ),
Alternatively, the output shaft rotational speed N _{0 of} the automatic transmission, the throttle opening θ, and the hydraulic oil temperature C are monitored, the inertia phase is detected, the engine torque is reduced, and at the same time a lockup clutch release command is issued. Therefore, firstly, the shift characteristics are improved by reducing the engine torque. That is, when the gear shift is performed without reducing the engine torque, the gear shift time becomes longer as shown by the broken line in FIG. 4, which is disadvantageous to the durability of the friction engagement device, and the gear shift time is shortened. When the working pressure of the friction engagement device is increased, the problem that the gear shift lock becomes large as shown by the chain line in FIG. 2 occurs, but in the present embodiment, both of them are overcome. Secondly, since the lockup clutch is released in the inertia phase (point e), there is no increase in engine speed or drop in output torque after gear shifting, and good gear shifting characteristics are obtained. Thirdly, when the inertia phase is detected, engine torque down is started, and the torque return command is issued near the end of the inertia phase. Therefore, when the engine torque control timing is controlled by the shift command or the timer control based on the shift judgment. A gear shift failure due to such a timing shift does not occur. That is, ΔT (corresponding to the time until the inertia phase starts after the shift command) corresponding to the return spring deflection time of the friction engagement device greatly changes due to various variations in oil temperature, running conditions, piston stroke, and the like. Therefore,
When the control is performed without depending on the method of directly detecting the inertia phase (that is, by the timer control), the timing of the torque down control may deviate from the actual timing of the inertia phase. As a result, when the timer value deviates from the actual gear shift and the gear shift is earlier than the engine torque control (when the engine torque control is too late from the proper time), for example, FIG.
As shown in, even if the engine enters the inertia phase, the engine speed Ne does not decrease easily, and the output shaft torque of the automatic transmission decreases once (due to the engine torque control executed late) after the completion of the gear change. The characteristic is to return to the normal level from (dotted line). On the contrary, when the gear shift is slower than the engine torque control (when the engine torque control is faster than the proper time), the output torque is reduced by executing the engine torque control before the gear shift is started, The engine torque is restored before the completion, and the engagement time becomes very long (because the gear shift is executed in the state where the engine torque is restored), which causes a problem that the durability of the friction engagement device deteriorates. (Two-dot chain line). In this embodiment, the detection of the inertia phase is used as a condition for reducing the engine torque, so that the above-mentioned trouble (as controlled by a timer) does not occur. If the engine torque return speed is not appropriate, for example, as shown in FIG. 5 (B), when the torque return time T ₀ is short, the gear shift time becomes long and the friction engagement device becomes durable. Worsening (one-dot chain line), and conversely, the time to return T ₀
If is too long, the output shaft torque of the automatic transmission will drop (solid line) and other problems will occur.
However, in this embodiment, since T ₀ is determined according to the type of shift, the throttle opening, and the shift pattern, extremely good shift characteristics can be obtained. Furthermore, if a large change in engine load (for example, throttle opening) occurs during gear shifting, unless the engine torque reduction amount corresponding to the engine load is corrected, for example, as shown in FIG. 5 (C), When the engine load increases, the shift time becomes longer accordingly and the durability of the friction engagement device deteriorates. In this embodiment, the torque reduction amount and the return speed are variable according to the change in the engine load, so this problem can be avoided. In the above embodiment, the throttle opening is represented as the engine load, but the engine load may directly detect the output shaft torque of the engine by a torque sensor, for example.

【The invention's effect】

As described above, according to the present invention, the base point of the engine torque reduction timing can be recognized accurately at an early stage without error, and the shift shock is small and the shift time is short while maintaining the shift transient characteristics. An excellent effect that the durability of the engagement device can be improved is obtained.

[Brief description of drawings]

FIG. 1 is a flow chart showing the essential configuration of the present invention, FIG. 2 is a control timing diagram for explaining the operation of the embodiment of the present invention, and FIG. 3 is a selection map of torque return speed in a normal pattern. FIGS. 4 and 5 (A) to (C) are transmission transient characteristic diagrams showing the comparison between the control timing and the case where the control amount is not optimal and the optimal case, FIG. 6 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 above embodiment is applied, and FIG. It is a block diagram which extracts and shows an output relationship. 102 …… Slottle sensor (engine load sensor), 108 …… Crank angle sensor (engine speed sensor:
Used in place of input shaft rotation speed sensor of automatic transmission when lockup is ON), 110 …… vehicle speed sensor, 113 …… transmission operating oil temperature sensor, Ne …… engine rotation speed, P …… hydraulic pressure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-69738 (JP, A) JP-A-55-80013 (JP, A) JP-A-60-248445 (JP, A)

Claims (1)

(57) [Claims] 1. An upshift control device for an automatic transmission, configured to maintain good gear shifting characteristics by reducing engine torque during upshift, in order to detect the start timing of the engine torque reduction control. A means for detecting the input shaft rotation speed of the automatic transmission, a means for detecting the output shaft rotation speed of the automatic transmission, and a product of the output shaft rotation speed and the gear ratio of the automatic transmission before the upshift. And a means for determining a reference value related to the start of the inertia phase, and a means for detecting whether or not the input shaft rotation speed of the automatic transmission is lower than the reference value. An upshift control for an automatic transmission characterized in that, when it is detected that the shaft rotation speed falls below the reference value, the start timing of the engine torque reduction control starts. Apparatus.