JPH08277932A - Lock-up clutch control device and method - Google Patents

Abstract

PURPOSE: To enable lockup on a low speed side and remarkably improve fuel consumption performance by sensing a shaft torque fluctuation in the start that a lockup clutch is in a lockup state, and varying fastening pressure when a signal in respect to the torque fluctuation exceeds a first specified value while being not more than a second specified value. CONSTITUTION: Signals are input to an ECU 8 from an air flow sensor 10, an output shaft torque sensor 16, and a throttle sensor 18 during driving a car. It is determined whether or not a torque to be required by a driver is obtained from a variation rate of a throttle opening. When it is NO, an allowable torque fluctuation rate ΔTA is set. An actual torque fluctuation rate TR is calculated from an actual torque. They are compared with each other. When ΔTR is not less than ΔTA, a slippage rate is checked. When the slippage rate is excessive, the lockup is released. When the slippage rate is in an allowable range, a lockup fastening hydraulic pressure is reduced such that torque fluctuation is in an allowable range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powertrain control device for an automobile, which relates to a power transmission mechanism for converting a driving force of an engine by an automatic transmission and transmitting the same to an axle.

[0002]

2. Description of the Related Art When an automatic transmission (hereinafter abbreviated as AT) is equipped with a torque converter, it has a torque amplifying effect and can be started easily, but it always causes slippage, which is a major factor that deteriorates fuel efficiency. Therefore, recently, a method has been known in which a direct coupling clutch (hereinafter abbreviated as lockup clutch) is built in the torque converter.

That is, the document "Nissan Full Range Electronic Control Automatic Transmission Maintenance Manual RE4R"
No. 01A1987 ", a lockup clutch is built in the torque converter, and the power of the engine is directly transmitted by the lockup clutch without going through the torque converter. Further, this lock-up mechanism not only completely locks up, but also performs slip lock-up that allows a slight slip under specific conditions.

Further, Japanese Laid-Open Patent Publication No. 3-194263 discloses a shock absorber that reduces shocks due to a sudden change in the torque of the turbine when the lockup clutch is engaged.
When the amount of change in the turbine torque exceeds the set value when the lockup clutch is engaged, the increase in the engaging force is suppressed.

[0005]

However, in the above-mentioned prior art, when the vehicle is locked up because the engine vibration or the resonance of the drive system including the transmission and muffled noise are generated at low vehicle speeds, the riding comfort deteriorates and the clutch itself. Deterioration is inevitable. The wider the lock-up usage area is, the better the fuel economy is.However, vibration and noise are caused by the excitation force due to engine rotation fluctuations, and the larger the low-speed and high-load, the higher the lock-up possible vehicle speed range. There was a problem that it was unavoidable to set and avoid the above problem.

To compensate for the above-mentioned drawback, a slip lock-up control method has been devised in which the lock-up engagement pressure is feedback-controlled in accordance with the deviation of the rotational speed between the input and output of the torque converter in the low vehicle speed range. Since there is no direct relationship between, there remains a problem in control accuracy and responsiveness.

Further, Japanese Patent Laid-Open No. 3-194263 discloses a shock at the time of lock-up engagement, and does not disclose a torque fluctuation and a shock in a state where the lock-up state is maintained.

The object of the present invention is to detect the input shaft torque of the torque converter while maintaining the smooth riding comfort, which is an advantage of the torque converter, by detecting the output shaft torque of the torque converter in the lockup state. Thus, it is possible to provide a torque converter control method that enables lockup from a low speed by setting a necessary and sufficient minimum engagement pressure and achieves a significant improvement in fuel consumption.

[0009]

The above object is to detect the shaft torque of a lockup clutch built in a torque converter and to detect the shaft torque fluctuation when the lockup clutch is in a lockup state. If the signal corresponding to the torque fluctuation exceeds the first predetermined value and the second
The lock-up clutch engagement pressure control means is provided for changing the engagement pressure when the value is less than the predetermined value. Further, the above object is to provide an output shaft torque detecting means for a lockup clutch such as a torque sensor or an estimated torque calculating device, a detecting means for detecting an output shaft torque fluctuation of the lockup clutch, and a torque fluctuation amount thereof having a predetermined value. Lockup clutch engagement pressure control means for changing the engagement pressure of the lockup clutch, and further, input shaft torque detection means of the lockup clutch, and lockup engagement according to the input shaft torque. Providing a setting means for setting the pressure,
Can be achieved by

[0010]

The input shaft torque of the torque converter can be calculated back from the output shaft torque, and the clutch engagement pressure for the input shaft torque is determined by the friction coefficient of the clutch, the clutch structure, and the like. Therefore, steadily set the clutch engagement pressure that corresponds to the input shaft torque, and lower the clutch engagement pressure when torque fluctuations that cause vibration and noise due to vehicle speed drop, load changes, etc. are detected. Set to slip lock-up state. When the output shaft torque stabilizes, set the fastening pressure to match the output shaft torque again.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a system configuration diagram of an embodiment.
1 is an engine, 2 is an automatic transmission, 3 is a propeller shaft, 4 is a differential device, 5 is a drive wheel, 6 is an AT hydraulic circuit,
7 is an AT control unit (hereinafter referred to as ATCU), 8 is an engine control unit (hereinafter, referred to as ATCU)
It is called ECU. ), 9 is an air cleaner, 10 is an air flow sensor, 11 is a throttle controller, 12 is an intake manifold, and 13 is an injector. A torque converter 14 and a gear train 15 are separated inside the AT, and an output shaft torque sensor 16 and an output shaft rotation speed sensor 17 of the automatic transmission are also attached. The ECU 8 receives input signals from the crank angle sensor 21, the air flow sensor 10, the throttle sensor 18, etc., and calculates the engine speed and the like. Then, a valve opening drive signal is output to the injector 13 to control the fuel amount. Further, a valve opening drive signal is output to the idle speed control valve 19 (hereinafter referred to as ISC valve) to control the corrected air amount. Although not shown, an ignition signal is output to the spark plug to control the ignition timing and the like.

On the other hand, the ATCU 7 is an output shaft torque sensor 1
6. Various calculations are executed based on input signals from the output shaft rotation sensor 17, the AT oil temperature sensor 21, and the like, and information such as engine speed and throttle opening obtained from the ECU 8. Then, a valve opening drive signal or the like is output to the switching solenoid valve 20 of the hydraulic circuit 6.

FIG. 2 shows a schematic structure of a control portion of the above ATCU and ECU. The control part is at least the bus 3
4, the CPU 33 and the input / output interface circuit 3
8 and a ROM 35 and a RAM 36. Depending on the control needs, the ATC as shown in FIG.
LAN control circuit 3 when U7 and ECU 8 are connected
7 etc. will be added.

The characteristic parts of this embodiment will be described below.

Originally, the lockup is stored in advance as a function of the vehicle speed, the throttle opening degree, etc. like the shift map, and the lockup operation will be performed only in that region. FIG. 3 shows the lockup clutch by replacing it with the most basic torque transmission system. Tp is an input shaft torque, Tt is an output shaft torque, and 40 is a clutch for engaging the input and output shafts. Here, if the clutch torque is Tc, the friction coefficient of the clutch is μ, the number of clutches is z, the clutch radius is r, and the clutch hydraulic pressure is P, the following formula is established.

Tc = P · μ · z · r (Equation 1), and when the clutch hydraulic pressure is calculated with the input shaft torque = the clutch torque, P = Tp / (μ · z · r) (Equation 2) The required clutch hydraulic pressure for the shaft torque is required.

Using this, the lock-up hydraulic pressure P in the steady state
(LU) is set.

P (LU) = Tp / (μ · z · r) + α (Equation 3) Here, α is a margin, but it may be a function according to the vehicle speed or the input shaft torque.

FIG. 4 shows a lock-up hydraulic pressure setting flowchart in a steady state. First, at step 50, the torque converter output shaft torque Tt is obtained from the output of the torque sensor 16.

Next, the torque converter output shaft torque Tt is converted into the torque converter input shaft torque Tp in order to obtain the required lockup hydraulic pressure. It is considered that the input / output torques are almost the same when the clutch is engaged with zero slip, but the torque converter input shaft torque Tp needs to be obtained by another method when the slip is present. Generally, during steady-state lockup, the AT is completely engaged in a predetermined gear ratio. Therefore, the AT from the output shaft speed sensor 17
By multiplying the output shaft rotational speed (hereinafter abbreviated as VSP) by the gear ratio G, the input shaft rotational speed Nt (hereinafter referred to as turbine rotational speed) of the automatic transmission can be accurately obtained.

Nt = G · VSP (Equation 5) Next, the slip ratio e is obtained based on the following equation: e = Nt / Ne (Equation 6) The torque ratio t characteristic of the torque converter 14 stored in advance (hereinafter , E-t characteristic), it can be expressed by the equation (7).

Tp = To / t (Equation 7) In step 52, the lockup hydraulic pressure P (LU) in the steady state is obtained from (Equation 3).

In step 54, the oil pressure P (LU) obtained in the above step is converted based on a hydraulic-electric command value conversion map stored in advance (step 53), and then the oil pressure to the lockup clutch is actually applied. Output the solenoid valve to control. With this flow, it becomes possible to set the necessary and sufficient lockup engagement hydraulic pressure.

FIG. 5 shows a control flow chart when the torque fluctuation is detected using the lockup hydraulic pressure setting algorithm in the steady state.

First, in step 60, it is judged whether or not the torque change is intended by the driver, based on whether or not the change amount ΔTVO of the throttle opening TVO is larger than a predetermined value K1. If it is large, it is regarded as the torque change intended by the driver, and the above-mentioned steady-state lockup hydraulic pressure setting algorithm is executed in step 61. On the other hand, when the change in the throttle opening is small, in the next steps 62 and 63, the allowable torque fluctuation amount ΔTA is set and the actual torque fluctuation amount ΔTR obtained from the actual torque value actually calculated in the lock-up hydraulic pressure setting algorithm. Calculate. Here, the allowable torque fluctuation amount ΔTA is stored in advance as at least one function of TVO, Ne and VSP. Further, the actual torque fluctuation amount ΔTR is obtained as a difference between the minimum value and the maximum value within a certain period. Then, in step 64, the allowable torque fluctuation amount ΔTA and the actual torque fluctuation amount ΔTR are compared.

If the actual torque fluctuation amount ΔTR <the permissible torque fluctuation amount ΔTA, the process ends without doing anything. On the contrary, if the actual torque fluctuation amount ΔTR ≧ the allowable torque fluctuation amount ΔTA, the process proceeds to step 65 to check the slip amount. The slip amount is expressed as 1Ne-Nt1. However, if the slip amount is too large, it may cause abrasion of the facing material, so in step 66, once the lockup is completely released, the lockup is continued until the lockup area is entered again. Keep up-released. However, if the slip amount is within the allowable value K2, the process proceeds to the next step 67. In step 67, the lockup engagement hydraulic pressure P (LU) is reduced by a certain function f so that the torque fluctuation is within the allowable value. This is the torque fluctuation difference (ΔTA-ΔTR), the slip amount 1Ne-Nt1,
It is assumed that it is stored in advance as at least one function of the engine speed Ne and the output shaft speed VSP. This flow can maintain a smooth riding comfort.

In the above embodiment, the torque fluctuation is directly obtained from the output shaft torque. However, if the input shaft side has a torque detecting means, in the lock-up state, the input torque is approximately equal to the output shaft torque. Therefore, the same control can be realized.

Next, another embodiment will be described. This is an embodiment when there is no torque sensor as shown in FIG. 1, and the actual torque is estimated from the existing signal instead of the output of the torque sensor. A torque estimation flowchart is shown in FIG.
First, at step 70, the throttle opening TVO is taken in, and at step 71, the engine speed Ne is taken in. These may be directly captured by the ATCU, or may receive signals via the ECU. In step 72, the engine torque Te is obtained from the engine torque map (shown in FIG. 7) which is a function of TVO and Ne. Then engine torque Te
The input shaft torque Tp is obtained by subtracting the auxiliary machine torque Tacc from the above.

Tp = Te−Tacc (Equation 8) Still another embodiment will be shown. This case is also an embodiment in the case where there is no torque sensor as shown in FIG. 1, and the actual torque is estimated from the existing signal instead of the output of the torque sensor. A torque estimation flowchart is shown in FIG. First, in the first step 80, the output shaft speed VSP is acquired, and in step 81, the engine speed Ne is acquired. The engine speed Ne may be directly fetched by the ATCU, or a signal may be received via the ECU. In step 82, the slip ratio e is obtained from the equation (Equation 6). Next, at step 83, the pump displacement coefficient τ is obtained from the pump displacement coefficient τ characteristic of the torque converter 14 (hereinafter referred to as e−τ characteristic) which is stored in advance. Finally, at step 84, the input shaft torque Tp of the torque converter can be expressed by the equation (Equation 9).

Tp = τ · Ne ^ 2 (Equation 9) Further, although not shown, when the engine braking state is determined by detecting the engine braking state from the throttle opening TVO, the engine speed Ne, and the vehicle speed VSP. May use the output shaft torque detecting means instead of the input shaft torque detecting means. As a result, it is possible to prevent a drive torque error from occurring during engine braking.

[0032]

According to the present invention, by detecting the output shaft torque of the torque converter, the smooth riding comfort, which is an advantage of the torque converter, is maintained, while detecting the input shaft torque of the torque converter, the necessary and sufficient minimum value is obtained. It is possible to provide a torque converter control method capable of setting the engagement pressure and achieving a significant improvement in fuel consumption. In addition, lockup at low vehicle speeds is possible and engine braking is improved. Further, the torque detecting means can be used not only for the main lockup control but also for any powertrain control, and it is possible to provide a powertrain control device and method for a vehicle, which has good fuel efficiency in total and excellent drivability.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment according to the present invention.

FIG. 2 is a configuration diagram of a control device according to an embodiment of the present invention.

FIG. 3 is a basic configuration diagram of a torque transmission system.

FIG. 4 is a flowchart showing a steady-state lockup hydraulic pressure setting.

FIG. 5 is a flowchart of torque fluctuation detection and lockup control.

FIG. 6 is a torque estimation flowchart (1) according to another embodiment of the present invention.

FIG. 7 is an engine torque characteristic diagram.

FIG. 8 is a torque estimation flowchart (2) according to another embodiment of the present invention.

FIG. 9 is a characteristic diagram of a pump capacity coefficient τ.

[Explanation of symbols]

1 ... Engine, 2 ... Automatic transmission, 3 ... Drive shaft, 4 ... Differential device, 5 ... Drive wheel, 6 ... Hydraulic circuit, 7 ... ATCU, 8 ...
ECU, 9 ... Air cleaner, 10 ... Air flow sensor,
11 ... Throttle controller, 12 ... Intake manifold, 13
... injector, 14 ... torque converter, 15 ... gear train, 16 ... output shaft torque sensor, 17 ... output shaft rotation speed sensor, 18 ... throttle sensor, 19 ... ISC valve, 20 ... switching solenoid valve, 21 ... crank angle sensor, Two
2 ... AT oil temperature sensor, 33 ... CPU, 34 ... Bus, 35
... ROM, 36 ... RAM, 37 ... LAN control circuit, 38
... I / O interface circuit, 40 ... Fastening clutch.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area F16H 59:42 59:46

Claims (9)

[Claims] 1. A powertrain control device for an automobile, comprising an engine, an automatic transmission including a torque converter, and at least one control device for controlling the engine and the automatic transmission, wherein the torque is A shaft torque detecting means for a lockup clutch built in the converter and a shaft torque fluctuation when the lockup clutch is in a lockup state are detected, and a signal corresponding to the torque fluctuation indicates a first predetermined value. A lock-up control device comprising lock-up clutch engagement pressure control means for changing the engagement pressure when the pressure exceeds the second predetermined value. 2. The lockup device according to claim 1, wherein the detection of the shaft torque fluctuation is obtained by detecting the output shaft torque fluctuation. 3. A powertrain control device for an automobile, comprising an engine, an automatic transmission having a torque converter, and at least one control device for controlling the engine and the automatic transmission, wherein the torque is Output shaft torque detection means of the lock-up clutch built in the converter, detection means for detecting shaft torque fluctuation when the lock-up clutch is in the lock-up state, and the torque fluctuation amount exceeds a predetermined value and the slip amount Is smaller than a predetermined value, lockup clutch engagement pressure control means for changing the engagement pressure of the lockup clutch is provided. 4. The lockup device according to claim 3, wherein the detection of the shaft torque fluctuation is obtained by detecting the output shaft torque fluctuation. 5. A powertrain control device for an automobile, comprising an engine, an automatic transmission having a torque converter, and at least one control device for controlling the engine and the automatic transmission, wherein the torque is A lockup comprising input shaft torque detection means for a lockup clutch built in the converter, and setting means for setting a lockup engagement pressure according to the input shaft torque detected by the detection means. Control device. 6. A powertrain control device for an automobile, comprising an engine, an automatic transmission having a torque converter, and at least one control device for controlling the engine and the automatic transmission, wherein the torque is Input shaft torque detection means for the lockup clutch built in the converter, conversion means for guiding the lockup clutch output shaft torque from the lockup clutch input shaft torque detection means, and output shaft torque for the lockup clutch And a lockup clutch engagement pressure control means for changing the engagement pressure of the lockup clutch when the torque variation exceeds a predetermined value and the slip amount is smaller than the predetermined value. A lock-up control device characterized by. 7. The lockup control device according to claim 5, wherein a torque sensor as the input shaft torque detecting means, an input signal such as a throttle opening and an engine speed, and the input. A characteristic map of the engine showing the relationship between the signal and the engine torque, a characteristic map of the torque converter showing the relationship between the input signal such as the output shaft speed and the input shaft speed and the input signal and the pump displacement coefficient, A lockup control method, characterized in that at least one of them is used. 8. The lockup control device according to claim 1, claim 2, claim 3, claim 4, claim 5 or claim 6, wherein a torque sensor is built in the automatic transmission as the torque detection means. A lockup control device characterized by the above. 9. A lock-up control, characterized in that, when an engine braking state is detected when the throttle is fully closed, the input shaft torque according to claim 5 is replaced with the output shaft torque and the subsequent engagement pressure is set. Method.