Power train control device

Abstract

To provide a control device for a power train that can restrain a speed change shock while restraining slowness of starting when the temperature of hydraulic oil of an automatic transmission is low.SOLUTION: A control device for a power train according to the present invention comprises an oil temperature information acquisition unit for acquiring information related to the temperature of hydraulic oil of an automatic transmission, a first output torque control unit for increasing the output torque of an internal combustion engine as the temperature of the hydraulic oil becomes lower, and a second output torque control unit for decreasing the output torque of the internal combustion engine from the output torque controlled by the first output torque control unit as the temperature of the hydraulic oil becomes lower when the automatic transmission changes speed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for a power train.

Background Art

[0002] The control device for a power train of Patent Document 1 includes engine output adjustment means for adjusting the output of an engine based on the temperature of the hydraulic oil of an automatic transmission.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when the temperature of the hydraulic oil of the automatic transmission is low and the friction of the automatic transmission is large, if the output torque of the internal combustion engine is increased and corrected, the friction component of the automatic transmission is offset, and the vehicle speed increase (in other words, the increase in the engine speed) at the time of vehicle start will be faster. However, since the temperature of the hydraulic oil of the automatic transmission is low and the shift response in the automatic transmission is slow, there is a possibility that shift shocks (specifically, surges and drops in engine rotation) may occur.

[0005] The present invention has been made in view of the conventional situation, and an object thereof is to provide a control device for a power train that can suppress shift shocks while suppressing the sluggishness of starting when the temperature of the hydraulic oil of the automatic transmission is low.

Means for Solving the Problems

[0006] The control device for a power train according to the present invention, in one aspect, includes an oil temperature information acquisition unit that acquires information regarding the temperature of the hydraulic oil of an automatic transmission, Internal combustion enginea first output torque control unit that increases the output torque such that the lower the temperature of the hydraulic fluid, and when the automatic transmission shifts gears, the output torque of the internal combustion engine is reduced from the output torque controlled by the first output torque control unit by an amount that is greater as the temperature of the hydraulic fluid is lower Larger than and a second output torque control unit.

Advantages of the Invention

[0007] According to the present invention, it is possible to suppress shift shocks while suppressing the jerks during starting when the temperature of the hydraulic fluid of the automatic transmission is low.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of a control device for a powertrain according to the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing one aspect of a vehicle powertrain. The powertrain 30 includes an internal combustion engine 1 and a hydraulic automatic transmission 3. A hydraulic automatic transmission 3 having a stepped transmission section is connected to the output shaft of the internal combustion engine 1 via a fluid torque converter 2. Note that the automatic transmission 3 can be, for example, a continuously variable transmission equipped with pulleys and a belt.

[0010] The engine control controller 4 (engine control device) includes a microcomputer and controls control signals for controlling the operation of the internal combustion engine 1. Specifically, the engine control controller 4 has, as software, functions for controlling the intake air amount, fuel injection amount, ignition timing, etc. of the internal combustion engine 1.

[0011] The automatic transmission control controller 7 (automatic transmission control device) includes a microcomputer and controls control signals for controlling the operation of the automatic transmission 3. Specifically, the automatic transmission control controller 7 has, as software, functions for controlling shifting, lock-up, etc. in the automatic transmission 3.

[0012] The engine control controller 4 acquires output signals of various sensors that detect the operating state of the internal combustion engine 1, and detects and recognizes the operating state of the internal combustion engine 1 based on the acquired signals. The internal combustion engine 1 includes an air flow sensor 11 that outputs a signal corresponding to the intake air flow rate QA of the internal combustion engine 1, an engine rotation sensor 12 that outputs a signal corresponding to the rotational speed NE of the internal combustion engine 1, a throttle sensor 14 that outputs a signal corresponding to the opening degree TVO of the electronic control throttle valve 13, a water temperature sensor 15 that outputs a signal corresponding to the water temperature TW of the cooling water of the internal combustion engine 1, etc. as sensors for detecting the operating state of the internal combustion engine 1.

[0013] The automatic transmission control controller 7 acquires output signals of various sensors that detect the operating state of the automatic transmission 3, and detects and recognizes the operating state of the automatic transmission 3 based on the acquired signals. The automatic transmission 3 includes a vehicle speed sensor 16 that outputs a signal corresponding to the rotation of the output shaft of the automatic transmission 3 (in other words, a signal corresponding to the vehicle speed VSP), a turbine sensor 17 that outputs a signal corresponding to the turbine rotational speed NT of the fluid torque converter 2, an oil temperature sensor 18 that outputs a signal corresponding to the oil temperature TAT which is the temperature of the working oil of the automatic transmission 3, a shift position sensor 19 that outputs a signal corresponding to the shift position (D range, R range, N range, P range) of the automatic transmission 3, etc., as sensors for detecting the operating state of the automatic transmission 3.

[0014] Furthermore, the engine control controller 4 and the automatic transmission control controller 7 are connected to a communication line 21 such as a bus of an in-vehicle network, and the engine control controller 4 and the automatic transmission control controller 7 communicate with each other via the communication line 21. The engine control controller 4 transmits information regarding the operating state of the internal combustion engine 1, such as engine load and throttle opening, to the automatic transmission control controller 7, and also transmits command signals such as a torque down permission signal and a lock-up prohibition signal. On the other hand, the automatic transmission control controller 7 transmits, for example, a torque down signal, a signal indicating the lock-up state, information on the oil temperature TAT, etc., to the engine control controller 4.

[0015] Here, the engine control controller 4 has an oil temperature information acquisition unit that acquires information on the oil temperature TAT (in other words, information regarding the temperature of the working oil of the automatic transmission 3), and has a function of controlling the output torque of the internal combustion engine 1 based on the acquired information on the oil temperature TAT. In the following, the control function of the output torque based on the information on the oil temperature TAT is referred to as the output torque control function for the AT. The engine control controller 4 has, as an AT output torque control function, a first function (in other words, a first output torque control unit) that increases the output torque of the internal combustion engine 1 as the oil temperature TAT decreases, and a second function (in other words, a second output torque control unit) that decreases the output torque of the internal combustion engine 1 from the output torque controlled by the first function as the oil temperature TAT decreases when the automatic transmission 3 shifts gears.

[0016] Figure 2 is a flowchart showing one aspect of the AT output torque control function provided in the engine control controller 4. In step S101, the engine control controller 4 obtains the target output torque of the internal combustion engine 1 based on information such as the operation amount of the accelerator pedal (in other words, the accelerator opening). Note that the engine control controller 4 controls the opening of the electronic control throttle valve 13 based on the target output torque. That is, the engine control controller 4 controls the output torque of the internal combustion engine 1 to the target output torque by adjusting the intake air amount of the internal combustion engine 1.

[0017] Also, in step S102, the engine control controller 4 obtains the ignition timing in the ignition device provided in the internal combustion engine 1 based on information such as the operating state of the internal combustion engine 1, for example, engine load, engine rotational speed, and coolant temperature. Note that the ignition device includes a spark plug, an ignition coil, a power transistor, and the like. Also, the ignition timing is represented by the advance angle from top dead center.

[0018] Next, in step S103, the engine control controller 4 determines whether or not the shift position of the automatic transmission 3 is in the driving range (specifically, the D range or the R range). Here, when the shift position of the automatic transmission 3 is outside the driving range (specifically, the N range or the P range), the engine control controller 4 proceeds to step S112 and sets the target output torque obtained in step S101 and the ignition timing obtained in step S102 as the final control target values as they are. That is, when the shift position of the automatic transmission 3 is outside the driving range, the engine control controller 4 does not execute the AT output torque control function.

[0019] On the other hand, if the shift position of the automatic transmission 3 is in the driving range, the engine control controller 4 proceeds to step S104 and determines whether the information on the oil temperature TAT can be obtained from the automatic transmission control controller 7. If the engine control controller 4 can obtain the information on the oil temperature TAT, it bypasses step S105 and proceeds to step S106.

[0020] If the engine control controller 4 cannot obtain the information on the oil temperature TAT, it proceeds to step S105, performs the estimation process of the oil temperature TAT, and then proceeds to step S106. That is, the information on the oil temperature TAT used by the engine control controller 4 in the AT output torque control function may be either the detected value by the sensor or the estimated value based on the cooling water temperature of the internal combustion engine 1 or the like.

[0021] In step S105, the engine control controller 4 can estimate the oil temperature TAT based on the cooling water temperature of the internal combustion engine 1 at the start and the driving time of the transmission. Also, considering that the cumulative rotation speed of the turbine after starting the drive of the transmission is correlated with the stirring energy of the working oil, that is, the temperature rise amount, a value obtained by multiplying the integral value of the turbine rotation speed NT by a correction coefficient is added to the initial value to estimate the oil temperature TAT.

[0022] In step S106, the engine control controller 4 compares the oil temperature TAT with a threshold value and determines whether the automatic transmission 3 is in a cold state where the oil temperature TAT is lower than the threshold value. The above threshold value is a reference temperature for determining whether the friction of the automatic transmission 3 is large enough to require an increase correction of the output torque of the internal combustion engine 1. That is, when the oil temperature TAT is lower than the threshold value, the engine control controller 4 determines that the automatic transmission 3 is in a cold state, and the friction of the automatic transmission 3 is so large that an increase correction of the output torque of the internal combustion engine 1 is required.

[0023] When the engine control controller 4 can determine that the oil temperature TAT is higher than the threshold value and the warm-up of the automatic transmission 3 is completed, in other words, when the friction of the automatic transmission 3 is sufficiently low, the process proceeds to step S113, and the output torque control function for the AT is not executed. That is, the output torque control function for the AT is a control function for the cold state of the automatic transmission 3 (in other words, before the warm-up is completed). On the other hand, if the engine control controller 4 determines that the automatic transmission 3 is in a cold state, the process proceeds to step S107 and subsequent steps, and the output torque control function for the AT is executed.

[0024] In step S107, the engine control controller 4 sets an output torque correction value for increasing the output torque of the internal combustion engine 1 as the oil temperature TAT becomes lower. Figure 3 shows one aspect of the correlation between the oil temperature TAT and the output torque correction value. The engine control controller 4 sets the output torque correction value to zero when the oil temperature TAT is higher than the threshold value, that is, a value that does not increase-correct the output torque of the internal combustion engine 1. In addition, the engine control controller 4 sets the output torque correction value to a larger value as the oil temperature TAT becomes lower than the threshold value, and increases the output torque of the internal combustion engine 1 as the oil temperature TAT becomes lower.

[0025] Next, the engine control controller 4 proceeds to step S108, and performs a process of increasing and correcting the target output torque obtained in step S101 based on the output torque correction value obtained in step S107, or a process of advancing and correcting the ignition timing obtained in step S102 based on the output torque correction value obtained in step S107. In other words, in step S108, the engine control controller 4 increases the target output torque obtained in step S101 as the oil temperature TAT decreases, or advances the ignition timing obtained in step S107 as the oil temperature TAT decreases.

[0026] That is, the engine control controller 4 realizes the first function of increasing the output torque of the internal combustion engine 1 as the oil temperature TAT decreases by performing an increase correction of the target output torque or an advance correction of the ignition timing based on the output torque correction value in steps S107 and S108. Here, the increase correction of the target output torque is also an increase correction of the throttle opening or an increase correction of the intake air amount of the internal combustion engine 1.

[0027] When the automatic transmission 3 is in a cold state, the friction of the automatic transmission 3 increases, the shaft output of the automatic transmission 3 decreases, and the vehicle may jerk during starting. Therefore, the engine control controller 4 increases the output torque of the internal combustion engine 1 so as to compensate for the friction of the automatic transmission 3, thereby suppressing the vehicle from jerking even when the automatic transmission 3 is in a cold state.

[0028] Next, in steps S109 - S111, when the automatic transmission 3 shifts gears, the engine control controller 4 executes the second function of decreasing the output torque of the internal combustion engine 1 from the output torque controlled by the first function (steps S107 and S108) as the oil temperature TAT decreases. The engine control controller 4 determines whether or not it is in an upshift when the automatic transmission 3 shifts gears.

[0029] Here, when the automatic transmission 3 is not shifting gears, the engine control controller 4 bypasses steps S110 and S111 and proceeds to step S112, and sets the target output torque and ignition timing after the correction process in step S108 as the final control target values. That is, when not in the process of shifting gears, the engine control controller 4 does not execute the second function.

[0030] On the other hand, when the automatic transmission 3 is in the process of shifting gears, the engine control controller 4 proceeds to step S110 and sets a retard correction value for retarding the ignition timing based on the oil temperature TAT. Figure 4 shows one aspect of the correlation between the oil temperature TAT and the retard correction value. The engine control controller 4 sets a larger retard correction value as the oil temperature TAT is lower. When the ignition timing is retarded, the output torque of the internal combustion engine 1 decreases. Therefore, the retard correction value becomes a correction term for reducing the output torque of the internal combustion engine 1 as the oil temperature TAT is lower.

[0031] Next, the engine control controller 4 proceeds to step S111, performs a correction process of retarding the ignition timing by the retard correction value set in step S110, and then proceeds to step S112 to determine the control targets of the target output torque and the ignition timing. That is, the engine control controller 4 realizes a second function of reducing the output torque of the internal combustion engine 1 from the output torque controlled by the first function as the oil temperature TAT is lower by retarding the ignition timing according to the oil temperature TAT when the automatic transmission 3 shifts gears.

[0032] Here, when the engine control controller 4 performs an advance correction of the ignition timing in step S108, the ignition timing after this advance correction will be retarded in step S111. Also, when the engine control controller 4 does not perform an advance correction of the ignition timing in step S108, the ignition timing set in step S102 will be retarded in step S111. However, in any case, the engine control controller 4 will reduce the output torque of the internal combustion engine 1 increased by the first function by the retard correction of the ignition timing (second function) in steps S110 and S111.

[0033] Due to the increase in the output torque by the first function (steps S107 and S108), the friction of the automatic transmission in the cold state is offset, and the increase in vehicle speed (increase in engine rotational speed) during vehicle startup becomes faster. However, since the oil temperature TAT of the automatic transmission 3 is low and the shift response in the automatic transmission 3 is slow, there is a possibility of shift shock (engine rotational speed surging and dropping), and the lower the oil temperature TAT, the slower the shift response and the greater the possibility of a larger shift shock.

[0034] Therefore, when shifting occurs where engine rotational speed surges due to the release of the shift clutch, the engine control controller 4 reduces the output torque of the internal combustion engine 1 as the oil temperature TAT is lower, thereby suppressing the engine rotational speed surge, and then suppressing the engine rotational speed drop associated with the engagement operation of the shift clutch. In other words, since it can be predicted that the higher the oil temperature TAT, the greater the engine rotational speed surge, the engine control controller 4 does not feedback control to reduce the output torque of the internal combustion engine 1 based on the detection of the engine rotational speed surge, but rather acts on the reduction of the output torque by the oil temperature TAT in a feed-forward manner.

[0035] Here, if the process of reducing the output torque during shifting does not have high responsiveness, the engine rotational speed surge cannot be sufficiently suppressed. For this reason, the engine control controller 4 performs ignition timing retard correction instead of reducing the intake air amount to reduce the output torque of the internal combustion engine 1 in accordance with the shift operation.

[0036] As described above, the engine control controller 4 has a first function (first output torque control unit) that increases the output torque of the internal combustion engine 1 as the oil temperature TAT is lower, and a second function (second output torque control unit) that, when the automatic transmission 3 shifts, reduces the output torque of the internal combustion engine 1 from the output torque controlled by the first function as the oil temperature TAT is lower. Then, the engine control controller 4 can suppress shift shock while suppressing the occurrence of starting hesitation when the oil temperature TAT of the automatic transmission 3 is low (in other words, when the automatic transmission 3 is cold).

[0037] Figure 5 is a time chart showing the state of the correction process of the output torque of the internal combustion engine 1 and the state of changes in the vehicle speed and the engine rotational speed when the first function and the second function are executed. In Figure 5, the dashed-dotted line indicates the case where the first function is implemented and the second function is not implemented, and the solid line indicates the case where the first function and the second function are implemented. Note that in Figure 5, the engine control controller 4 executes, as a countermeasure against shift shock, the second function which is feedforward control, and a function of feedback-controlling the output torque (intake air amount or ignition timing) of the internal combustion engine 1 based on the deviation between the target engine rotational speed and the actual engine rotational speed at the time of shifting.

[0038] During the time period from time t1 to time t2 which is the shift period (upshift period), the second function of delaying the ignition timing more as the oil temperature TAT is lower is implemented, and the output torque of the internal combustion engine 1 is temporarily reduced. Thereby, since the overshoot of the engine rotational speed at the time of shifting is suppressed, the shift shock is suppressed and the shift response is improved.

[0039] Here, even while the second function of delaying the ignition timing more as the oil temperature TAT is lower is being implemented, the feedback control of the engine rotational speed is implemented. If the actual engine rotational speed is higher than the target engine rotational speed, the overshoot of the engine rotational speed is suppressed in cooperation with the second function. Also, when the rise of the engine rotation is excessively suppressed by the second function, the feedback control of the engine rotational speed increases the output torque so as to promote the rotation rise. Then, after time t2 when the shifting (in other words, the engagement of the shift clutch) is completed, the second function stops, and the feedback control of the engine rotational speed speeds up the rising response of the engine rotational speed.

[0040] Each of the technical concepts described in the above embodiments can be used in appropriate combination as long as no contradiction occurs. In addition, although the content of the present invention has been specifically described with reference to the preferred embodiments, it is obvious that those skilled in the art can adopt various modified forms based on the basic technical concept and teaching of the present invention.

Explanation of Reference Numerals

[0041] 1... Internal combustion engine, 3... Automatic transmission, 4... Engine control controller (control device), 7... Automatic transmission control controller, 18... Oil temperature sensor

Claims

1. A power train control device for controlling a power train in which a hydraulic automatic transmission is connected to an internal combustion engine, comprising: an oil temperature information acquisition unit that acquires information regarding the temperature of the hydraulic oil of the automatic transmission; a first output torque control unit that increases the output torque of the internal combustion engine as the temperature of the hydraulic oil decreases; a second output torque control unit that, when the automatic transmission shifts gears, decreases the output torque of the internal combustion engine by a greater amount as the temperature of the hydraulic oil decreases, from the output torque controlled by the first output torque control unit; A power train control device having the above components.

2. The power train control device according to Claim 1, wherein: the second output torque control unit decreases the output torque of the internal combustion engine by retarding the ignition timing of the internal combustion engine. A power train control device.

3. The power train control device according to Claim 2, wherein: the first output torque control unit increases the output torque of the internal combustion engine by advancing the ignition timing of the internal combustion engine or by increasing the intake air amount of the internal combustion engine. A power train control device.

4. The power train control device according to Claim 1, wherein: when the automatic transmission upshifts, the second output torque control unit decreases the output torque of the internal combustion engine by a greater amount as the temperature of the hydraulic oil decreases, from the output torque controlled by the first output torque control unit, so as to suppress a surge in the rotational speed of the internal combustion engine. A power train control device.

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