JP2010261571A - Control device for lock-up clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a lock-up clutch capable of more easily performing the slip control of the lock-up clutch. <P>SOLUTION: An electronic control unit 8 uses a formula of computation composed of a term for a difference between engine torque and a transmission torque capacity of a torque converter 3, a term for inertia torque calculated from a target engine revolving speed, and a feedback term based on deviation between the target engine revolving speed and an actual engine revolving speed to compute the target torque of the lock-up clutch 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control apparatus for a lockup clutch that controls a transmission torque of a lockup clutch to a target torque so that a necessary slip state can be obtained.

  Many automatic transmissions of a vehicle are provided with a lockup clutch that directly connects an engine and a drive system in order to reduce a fluid loss of torque in a torque converter and improve fuel efficiency. However, if the lockup is performed at a low vehicle speed, the torque fluctuation of the engine is directly transmitted to the drive wheels, which leads to a deterioration in drivability. Therefore, at low vehicle speed, the slip control of the lockup clutch that uses the lockup clutch while slipping with the minimum required slip amount is implemented to achieve both drivability and fuel efficiency. For example, in the lockup clutch control device described in Patent Document 1, the differential pressure of the lockup clutch is adjusted so that the slip rotation speed, which is the difference between the engine rotation speed and the turbine rotation speed, becomes a target value. Slip control is implemented.

JP 2001-380479 A

  By the way, the relationship between the slip rotation speed and the lockup clutch differential pressure is non-linear. That is, even if the slip rotation speed is the same, if the slip state of the torque converter is different, the lockup clutch differential pressure required to realize the necessary slip rotation speed changes. For this reason, the control device of Document 1 performs slip control using a non-linear model, and the control is very complicated.

  As another slip control method for the lockup clutch, the target engine speed is set so that the required slip speed can be obtained, and lockup based on the deviation between the target engine speed and the actual engine speed is performed. A method of performing feedback control of the clutch differential pressure is also conceivable. In this case as well, the relationship between the deviation of the engine speed and the lockup clutch differential pressure is also non-linear, so simply performing feedback control using the deviation between the target engine speed and the actual engine speed. Therefore, the slip state of the lockup clutch cannot be appropriately controlled. Therefore, even in such a case, precise tuning such as making the feedback gain variable according to the torque converter slip state is necessary, and the control is also complicated.

  The present invention has been made in view of such circumstances, and a problem to be solved is to provide a control device for a lockup clutch that can more easily perform slip control of the lockup clutch. .

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
In order to solve the above-described problem, the invention according to claim 1 is a lockup clutch control device that controls the transmission torque of the lockup clutch to a target torque so that a necessary slip state is obtained. The gist of the equation is that it includes a difference term between the engine torque and the torque transfer capacity of the torque converter.

  In the above configuration, the target torque of the lockup clutch is calculated using a calculation formula including a difference term between the engine torque and the transmission torque capacity of the torque converter. Thereby, since the nonlinearity of the system can be canceled by the difference term, the system can be linearized. Therefore, although the control structure is simple, the actual engine speed can be appropriately converged to the target engine speed regardless of the slip state of the torque converter. Therefore, according to the above configuration, slip control of the lockup clutch can be performed more easily.

  More specifically, for example, as described in claim 2, an inertia torque term calculated from the target engine speed and a feedback term based on a deviation between the actual value of the engine speed and the target value are included. The target torque of the lockup clutch can be calculated using the calculation formula.

  In order to solve the above problem, the invention according to claim 3 is a lockup clutch control device that controls the transmission torque of the lockup clutch to a target torque so that a necessary slip state is obtained. The gist is to calculate by the following equation (1).

上記構成では、上式（１）に示すように、エンジントルクとトルクコンバーターの伝達トルク容量との差の項、目標エンジン回転速度から演算されるイナーシャトルクの項、エンジン回転速度の実値と目標値との偏差に基づくフィードバック項により目標トルクの算出式が構成されている。こうした場合、エンジントルクとトルクコンバーターの伝達トルク容量との差の項を上記算出式に含めたことで、系の非線形性が相殺されるようになる。そのため、系を線形化することができる。そのため、簡易な制御構造でありながらも、トルクコンバーターのスリップ状態に拘わらず、実エンジン回転速度を目標エンジン回転速度に適切に収束させることができる。したがって上記構成によれば、ロックアップクラッチのスリップ制御をより簡易に行うことができるようになる。

In the above configuration, as shown in the above equation (1), the term of the difference between the engine torque and the transmission torque capacity of the torque converter, the term of inertia calculated from the target engine speed, the actual value of the engine speed and the target A target torque calculation formula is configured by a feedback term based on a deviation from the value. In such a case, the non-linearity of the system is canceled by including the term of the difference between the engine torque and the transmission torque capacity of the torque converter in the above calculation formula. Therefore, the system can be linearized. Therefore, although the control structure is simple, the actual engine speed can be appropriately converged to the target engine speed regardless of the slip state of the torque converter. Therefore, according to the above configuration, slip control of the lockup clutch can be performed more easily.

  Note that the transmission torque capacity of the torque converter can be calculated from the engine rotational speed or the turbine rotational speed and the capacity coefficient of the torque converter as described in claim 4.

  Further, the control for setting the transmission torque of the lockup clutch as the target torque can be performed by adjusting the differential pressure of the lockup clutch as described in claim 5.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows typically the whole structure about one Embodiment of this invention. The flowchart of the slip control routine of the lockup clutch employ | adopted as the same embodiment.

Hereinafter, an embodiment of a lockup clutch control device according to the present invention will be described in detail with reference to FIGS. 1 and 2.
First, the configuration of the lockup clutch control device of this embodiment will be described with reference to FIG. As shown in FIG. 1, an on-board engine (E / G) 1 is connected to an automatic transmission (A / T) 4 via a torque converter 3 having a lock-up clutch 2. The torque converter 3 is a kind of fluid coupling having a torque amplifying action, and the lockup clutch 2 mechanically directly connects the engine 1 and the automatic transmission 4 to reduce fluid loss due to slip of the torque converter 3. It is supposed to be.

  The lockup clutch 2 is operated by hydraulic oil supplied from the hydraulic control circuit 7 through the oil passages 5 and 6. Specifically, when release pressure is applied to the engine 1 side of the lockup clutch 2 through the oil passage 5 and hydraulic fluid is discharged from the automatic transmission 4 side of the lockup clutch 2 through the oil passage 6, the lockup clutch 2 Is released. On the other hand, when the hydraulic oil is discharged from the engine 1 side of the lockup clutch 2 through the oil passage 5 and the apply pressure adjusted by the hydraulic control circuit 7 is applied through the oil passage 6, the lockup clutch 2 is in a fully engaged state. Thus, the rotation of the engine 1 is directly input to the automatic transmission 4. Further, the release pressure applied to the engine 1 side of the lockup clutch 2 through the oil passage 5 and the apply pressure applied to the automatic transmission 4 side of the lockup clutch 2 through the oil passage 6 are adjusted appropriately. The lock-up clutch 2 is in a partially engaged slip state. As described above, the lockup clutch 2 is operated according to the difference in hydraulic pressure applied to the engine 1 side and the automatic transmission 4 side (lockup clutch differential pressure).

  The hydraulic control circuit 7 is controlled by an electronic control unit 8. The electronic control unit 8 temporarily stores a CPU for performing various arithmetic processes related to control of the lock-up clutch 2 and the like, a ROM in which a control program and data are stored, CPU calculation results, detection results of various sensors, and the like. It is configured to include a RAM to be stored and an I / O used for exchanging signals with the outside. The electronic control unit 8 is input with detection signals of various sensors for detecting the driving situation of the vehicle. For example, a rotational speed sensor 9 that detects the rotational speed of the engine 1, a throttle sensor 10 that detects the throttle opening of the engine 1, an accelerator sensor 11 that detects the accelerator operation amount of the driver, and an air flow that detects the intake air amount of the engine 1 Detection signals such as a meter 12 and a vehicle speed sensor 13 for detecting the vehicle speed are input to the electronic control unit 8.

  Now, in the lockup clutch control device of the present embodiment configured as described above, slip control of the lockup clutch 2 is performed as necessary. In the slip control of the lock-up clutch 2, the lock-up clutch 2 is brought into a partially engaged state by appropriately adjusting the differential pressure between the release pressure and the apply pressure, that is, the lock-up clutch differential pressure. ing. Such slip control of the lock-up clutch 2 is basically performed based on the deviation between the target engine speed set so that the lock-up clutch 2 is in the required slip state and the actual engine speed. This is done by feedback control of the transmission torque.

  In the present embodiment, the target torque T_cl, which is the target value of the transmission torque of the lockup clutch 2 at this time, is calculated by including a term of the difference between the engine torque T_e and the transmission torque capacity T_tc of the torque converter. It is made to calculate using. More specifically, the term of the difference between the engine torque T_e and the transmission torque capacity T_tc of the torque converter, the inertia torque calculated from the target engine speed ω_et, and the target engine speed ω_et and the actual engine speed ω_e The target torque T_cl is calculated using a calculation formula including a feedback term based on the deviation.

Hereinafter, how these calculation formulas are derived will be described.
First, the relationship of the following equation (2) holds among the actual engine speed ω_e, the engine torque T_e, the transmission torque capacity T_tc of the torque converter 3 and the transmission torque T_cl of the lockup clutch 2. Here, “I_e × dω_et / dt” on the left side of the following expression (2) represents an inertia torque of the engine 1, that is, a torque that can be used to increase the rotational speed of the engine 1 itself. That is, the following equation (2) is obtained by subtracting the torque transmitted to the automatic transmission 4 through the lock-up clutch 2 and the torque converter 3 from the torque generated by the engine 1 to increase the rotational speed of the engine 1 itself. It shows that it is an available inertia shuttle.

一方、上記ロックアップクラッチ２のスリップ制御では、実エンジン回転速度ω_eを目標エンジン回転速度ω_et に収束させるように実施される。ここでそうしたエンジン回転速度の収束の度合を評価するため、その評価用の関数である誤差エネルギー関数Ｖを設定する。ここでは、目標エンジン回転速度ω_et と実エンジン回転速度ω_eとの偏差の絶対値、及び同偏差の時間積分値の絶対値を「０」に近づけることを目標とするため、上記誤差エネルギー関数Ｖとして、次式（３）の関数を設定することとする。

On the other hand, the slip control of the lockup clutch 2 is performed so that the actual engine speed ω_e converges to the target engine speed ω_et. Here, in order to evaluate the degree of convergence of the engine speed, an error energy function V which is a function for the evaluation is set. Here, in order to make the absolute value of the deviation between the target engine speed ω_et and the actual engine speed ω_e and the absolute value of the time integral value of the deviation close to “0”, the error energy function V is The function of the following equation (3) is set.

ここで、「ｘ_1」を目標エンジン回転速度ω_et と実エンジン回転速度ω_eとの偏差とし、「ｘ_2」を同偏差の時間積分値とすると、下式（４）が成り立つ。すなわち、目標エンジン回転速度ω_et と実エンジン回転速度ω_eとの偏差ｘ_1は、同偏差の時間積分値ｘ_2の時間微分値となる。

Here, when “x_1” is a deviation between the target engine speed ω_et and the actual engine speed ω_e, and “x_2” is a time integral value of the deviation, the following expression (4) is established. That is, the deviation x_1 between the target engine speed ω_et and the actual engine speed ω_e is a time differential value of the time integral value x_2 of the deviation.

一方、目標エンジン回転速度ω_et と実エンジン回転速度ω_eとの偏差ｘ_1の時間微分値は、下式（５）の通りとなる。

On the other hand, the time differential value of the deviation x_1 between the target engine speed ω_et and the actual engine speed ω_e is expressed by the following equation (5).

ここで上式（２）の関係から、目標エンジン回転速度ω_et と実エンジン回転速度ω_eとの偏差ｘ_1の時間微分値は、下式（６）のように表すことができる。

Here, from the relationship of the above formula (2), the time differential value of the deviation x_1 between the target engine speed ω_et and the actual engine speed ω_e can be expressed as the following formula (6).

一方、上記誤差エネルギー関数Ｖを時間微分すると、下式（７）の関係が得られる。

On the other hand, when the error energy function V is differentiated with respect to time, the relationship of the following equation (7) is obtained.

ここで上式（７）に上式（６）の関係を代入すると、次式（８）が得られる。

If the relationship of the above equation (6) is substituted into the above equation (7), the following equation (8) is obtained.

更に上式（８）の中括弧内の式を「−Ｃｘ_1」と置くと、下式（９）の関係式が得られることになる。

Furthermore, when the expression in the braces of the above expression (8) is set to “−Cx_1”, the relational expression of the following expression (9) is obtained.

こうした式（９）の両辺に、エンジン１の慣性モーメントＩ_eをそれぞれ乗算すると、下式（１０）の関係式が得られる。

By multiplying both sides of the equation (9) by the moment of inertia I_e of the engine 1, a relational expression of the following equation (10) is obtained.

この式（１０）からは、次式（１１）が得られる。そして同式（１１）のようにロックアップクラッチ２の目標トルクＴ_cl を設定すれば、上記誤差エネルギー関数Ｖが時間の経過とともに収束するようになる。

From this equation (10), the following equation (11) is obtained. If the target torque T_cl of the lockup clutch 2 is set as shown in the equation (11), the error energy function V converges with time.

上式（１１）の「ＣＩ_e」、「Ｉ_eｋ_1」はそれぞれ定数であるため、これを定数「ｋ_p」、定数「ｋ_i」と置けば、次式（１２）の通りとなる。以上により、上記エンジントルクＴ_eとトルクコンバーターの伝達トルク容量Ｔ_tc との差の項、目標エンジン回転速度ω_et から演算されるイナーシャトルクの項、及び目標エンジン回転速度ω_et と実エンジン回転速度ω_eとの偏差に基づくフィードバック項からなる目標トルクＴ_cl の算出式が得られる。

Since “CI_e” and “I_ek — 1” in the above equation (11) are constants, if they are set as a constant “k_p” and a constant “k_i”, the following equation (12) is obtained. As described above, the difference term between the engine torque T_e and the transmission torque capacity T_tc of the torque converter, the inertia torque calculated from the target engine speed ω_et, and the deviation between the target engine speed ω_et and the actual engine speed ω_e. A calculation formula for the target torque T_cl consisting of a feedback term based on is obtained.

なおエンジントルクＴ_eは、エンジン１のスロットル開度や吸入空気量とエンジン回転速度ω_eとから推定することができる。またトルクコンバーター３の伝達トルク容量は、エンジン回転速度ω_e又はタービン回転速度とトルクコンバーター３の容量係数とから推定することができる。例えばトルクコンバーター３の容量係数とエンジン回転速度ω_eの二乗値との乗算値としてトルクコンバーター３の伝達トルク容量の推定値を算出することが可能である。

The engine torque T_e can be estimated from the throttle opening and intake air amount of the engine 1 and the engine rotational speed ω_e. Further, the transmission torque capacity of the torque converter 3 can be estimated from the engine speed ω_e or the turbine speed and the capacity coefficient of the torque converter 3. For example, it is possible to calculate an estimated value of the transmission torque capacity of the torque converter 3 as a multiplication value of the capacity coefficient of the torque converter 3 and the square value of the engine rotational speed ω_e.

  On the other hand, when the error energy function V of the above equation (3) is time-differentiated and the relationship of the above equations (2) and (12) is substituted, the following equation (13) is obtained. Here, since the constant k_i and the inertia moment I_e of the engine 1 are both positive values, the time differential value (dV / dt) of the error energy function V always takes a value of “0” or less. Therefore, the value of the error energy function V converges to “0” as time elapses. If the target torque T_cl is set based on the calculation formula (12), the actual engine speed ω_e is It can be seen that the target engine speed ω_et converges with time.

図２は、本実施形態に採用されるロックアップクラッチ２のスリップ制御ルーチンのフローチャートを示している。本ルーチンの処理は、ロックアップクラッチ２のスリップ制御の実施中に、電子制御ユニット８により周期的に繰り返し実施されるものとなっている。

FIG. 2 shows a flowchart of a slip control routine of the lockup clutch 2 employed in the present embodiment. The processing of this routine is repeatedly performed periodically by the electronic control unit 8 during the slip control of the lockup clutch 2.

  When this routine is started, the electronic control unit 8 first calculates a target engine speed in step S100. The calculation of the target engine rotational speed ω_et here is performed based on the vehicle speed, the engine load, and the like so as to obtain a necessary slip state.

  In subsequent step S101, the electronic control unit 8 calculates the target torque T_cl of the lockup clutch 2 using the above equation (12) based on the target engine speed ω_et calculated in step S100. Then, in the next step S102, the electronic control unit 8 sets the lockup clutch differential pressure so that the previously calculated target torque T_cl is obtained, and ends the processing of this routine.

According to the lockup clutch control device of the present embodiment described above, the following effects can be obtained.
In the present embodiment, the electronic control unit 8 calculates the target torque T_cl of the lockup clutch 2 by using a calculation formula (12) that includes a term of the difference between the engine torque T_e and the torque transfer capacity T_tc of the torque converter. It is made to calculate using. More specifically, the target torque T_cl is calculated using a calculation formula (12) including a term of a difference between the engine torque T_e and the transmission torque capacity T_tc of the torque converter, an inertia torque term, and a feedback term. In such a case, by including the term (T_e−T_tc) of the difference between the engine torque T_e and the transmission torque capacity T_tc of the torque converter 3 in the calculation formula (12), the nonlinearity of the system is canceled and the linearization can be performed. It becomes possible. Therefore, although the control structure is simple, the actual engine speed ω_e can be appropriately converged to the target engine speed ω_et regardless of the slip state of the torque converter 3. Therefore, according to the above configuration, slip control of the lockup clutch can be performed more easily.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, feedback control is performed on the target torque T_cl of the lockup clutch 2 and thus the lockup clutch differential pressure based on the deviation x_1 between the target engine speed ω_et and the actual engine speed ω_e and the time integral value x_2 thereof. I was trying to do it. Similar feedback control can also be performed based on the slip rotation speed of the lockup clutch 2 (the difference between the engine rotation speed and the turbine rotation speed). In this case, the deviation x_1 between the target engine speed ω_et and the actual engine speed ω_e and the time integral value x_2 of the above equation (12) are changed to the deviation between the target slip speed and the actual slip speed and the time integral value thereof. Instead, the target torque T_cl is calculated.

In the above embodiment, the feedback control of the target torque T_cl is performed by PI control, but may be performed by PID control, PD control, or P control.
In the above embodiment, the calculation formula (12) including the term of the difference between the engine torque T_e and the transmission torque capacity T_tc of the torque converter, the term of inertia calculated from the target engine speed ω_et, and the feedback term is used. The target torque T_cl was calculated. Such a calculation formula is not limited to this, and can be changed as appropriate. In any case, as long as the term for calculating the target torque T_cl includes the term of the difference between the engine torque T_e and the torque transfer capacity T_tc of the torque converter, the nonlinearity of the system can be offset, and the lockup clutch 2 slip control can be performed easily.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Lock-up clutch, 3 ... Torque converter, 4 ... Automatic transmission, 5, 6 ... Oil path, 7 ... Hydraulic control circuit, 8 ... Electronic control unit, 9 ... Rotational speed sensor, 10 ... Throttle sensor , 11 ... accelerator sensor, 12 ... air flow meter, 13 ... vehicle speed sensor.

Claims (5)

In a lockup clutch control device that controls a transmission torque of a lockup clutch to a target torque so that a necessary slip state is obtained,
A control device for a lockup clutch, wherein the term for calculating the target torque includes a term for a difference between an engine torque and a transmission torque capacity of a torque converter. The term of the target torque calculation formula includes an inertia torque calculated from the target engine speed and a feedback term based on a deviation between the target engine speed and the actual engine speed. 2. A control device for a lockup clutch according to 1. In a lockup clutch control device that controls a transmission torque of a lockup clutch to a target torque so that a necessary slip state is obtained,
The target torque is calculated by the following equation (1). A lockup clutch control device.

The control device for a lockup clutch according to any one of claims 1 to 3, wherein a transmission torque capacity of the torque converter is calculated from an engine rotation speed or a turbine rotation speed and a capacity coefficient of the torque converter. The lockup clutch according to any one of claims 1 to 4, wherein the control for setting the transmission torque of the lockup clutch as a target torque is performed by adjusting a differential pressure of the lockup clutch. Control device.

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