JPH08170725A - Controller of torque converter with lock-up clutch - Google Patents

Abstract

PURPOSE: To enable the proper control of a lock-up clutch in response to various operation conditions by outputting specific control signals related to specific difference in pressure, number of revolutions, and torque to a solenoid valve for controlling liquid pressure by a solenoid valve control section when a lock-up piston is tightened. CONSTITUTION: A solenoid valve control section 44 outputs a control signal which makes a difference in pressure between a converter chamber 20 and a lock-up chamber 21 the maximum pressure until pressure change rate calculated by a pressure change rate calculating section 50 reaches a predetermined value when a lock-up piston 3 is tightened, and a solenoid valve for controlling liquid pressure 25 is driven by the control signal. When pressure change rate drops below a predetermined value, it returns to a predetermined control signal which corresponds to the number of revolutions of a pump impeller of a torque converter 4 as input and output elements and a turbine runner. After that, the solenoid valve for controlling liquid pressure 25 is driven by a control signal which increases at a speed which corresponds to torque of the turbine runner calculated based on a ratio of input speed to output speed detected by a speed ratio detection section 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a torque converter with a lockup clutch.

[0002]

2. Description of the Related Art As a torque converter with a lockup clutch, for example, a torque converter disclosed in Japanese Patent Laid-Open No. 60-143267 is known.

The torque converter will be briefly described. The torque converter includes a clutch control means capable of controlling a slip amount between input / output elements to a set value via a clutch whose coupling force is adjusted by fluid pressure. A temperature detecting means for detecting the temperature of the fluid, and a control gain changing means for changing the control gain of the clutch control means according to the temperature. More specifically, the control gain control means has a solenoid valve solenoid for fluid pressure control that adjusts the fluid pressure in order to adjust the coupling force of the clutch, and the control gain control means controls the duty ratio of the pulse signal applied to the solenoid valve solenoid. The fluid pressure is controlled by varying.

The clutch is referred to as a lockup clutch, and when the running state of the vehicle enters the lockup region, the lockup clutch is engaged to directly connect the input / output elements and enter the non-lockup region. When this happens, the lockup clutch is released to put the input / output elements in the converter state.

[0005]

However, in such a conventional torque converter with a lock-up clutch,
Even if feedback control of the input / output speed is performed, the torque converter operating state, for example, the difference in speed ratio, or the difference in that the accelerator enters the lockup region with a constant accelerator or the accelerator enters the lockup region, etc. , The time until the lockup clutch is engaged varies.

That is, it is impossible to control all conditions by only adjusting the control constants. For this reason, there is a problem that the fuel efficiency cannot be effectively improved and an engagement shock occurs when the control delay is large.

More specifically, when the lockup command is issued, in the conventional example, as shown in FIG. 11, the duty ratio is set to the initial value Ds, and then the engine speed (the speed of the input element) is set. The deviation ΔN from the turbine rotation speed (the rotation speed of the output element) is calculated, and the integrated gain K
i and the proportional gain Kp are multiplied, the duty ratio is output from the following equation, and control is performed so that the change in engine rotation becomes smooth.

[0008] _{Di = DUTY0 + Ki · ΔN DUTY} = Di + Kp · ΔN DUTY 0 = Di

Here, Di is an integral term of the target duty ratio, and DUTY ₀ is an integrated value of the integral term.

In this control, the change in engine speed with respect to the release pressure is a large delay system. Therefore, if the initial value Ds of the duty ratio or the integral gain Ki is set too high, the duty ratio will change even if the engine speed does not change. Since the ratio is integrated and increases, the duty ratio has increased too much at the time when it starts to change, and the change in the engine speed becomes abrupt, causing a lockup clutch engagement shock.

Therefore, as shown in FIG. 11, the Ds and the integral gain Ki are given a small value to slowly increase the duty ratio, and the delay time of the change of the engine speed with respect to the change of the duty ratio is decreased to reduce the engine speed. It slowly drops to eliminate shock. Therefore, the time required for engagement becomes long, and the fuel efficiency effect decreases.

On the other hand, since the facing gap at the start of lock-up is greatly different between the case where the lock-up is performed with a constant accelerator opening and the case where the lock-up is performed from the coast state by depressing the accelerator, the time required to move the piston is different. There is also a problem that it is difficult to achieve both matching of control gains.

The present invention has been made in view of the above points, and it is an object of the present invention to appropriately control the lockup clutch in accordance with various operating conditions.

[0014]

The present invention adopts the following means in order to solve the above problems. (1) In the present invention, as shown in FIG. 1, (a) an input element that is rotationally driven by an engine, and (b) is driven and rotated by a fluid that flows with the rotation of the input element. An output element connected to the input shaft, and (c) a lock-up piston which is in the fluid between the input and output elements and which fastens or releases the input element and the output element by the differential pressure of the fluid hydraulic pressure received on both sides. (D) A solenoid valve for controlling hydraulic pressure, which is capable of controlling the hydraulic pressure of either one of the converter chamber and the lockup chamber or the pressure difference between these chambers, which are arranged on both sides of the lockup piston. (E) A control device for a torque converter with a lockup clutch, which includes: a solenoid valve control unit that outputs a control signal to the hydraulic control solenoid valve, the control signal indicating that the lockup piston should be engaged according to the running state of the vehicle. In (f) a pressure detection unit that detects the hydraulic pressure of either the converter chamber or the lockup chamber or the differential pressure between these chambers, and (g) the pressure detection unit that detects this pressure from the pressure detected by the pressure detection unit. A pressure change rate calculating section for calculating a change rate; and (h) a speed ratio detecting section for detecting a speed ratio of the input / output elements, wherein the solenoid valve control section, when engaging the lockup piston, Until the pressure change rate calculated by the pressure change rate calculation unit reaches a predetermined value, a control signal that maximizes the differential pressure between the converter chamber and the lockup chamber is output, and the pressure change rate becomes a predetermined value or less. At that time, the control signal is returned to a predetermined control signal according to the number of revolutions of the input / output element, and thereafter, a control signal that increases at a speed corresponding to the torque of the output element calculated based on the input / output speed ratio detected by the speed ratio detection unit is set. Solenoid valve for hydraulic control And outputs (corresponding to claim 1).

(2) Further, according to the present invention, the control signal returned when the rate of pressure change in the solenoid valve control unit becomes equal to or less than a predetermined value is determined based on the pressure value detected by the pressure detection unit. Is set (corresponding to claim 2).

(3) Further, according to the present invention, the relationship between the speed ratio of the input / output elements and the torque capacity coefficient is determined in obtaining the increasing speed of the control signal according to the torque of the output element in the solenoid valve control section. The first map and the second map defining the relationship between the torque of the output element and the increasing speed of the control signal are used (corresponding to claim 3).

(4) Further, the increasing speed of the control signal in accordance with the torque of the output element in the solenoid valve control section is increased as the torque of the output element is increased (corresponding to claim 4). ).

[0018]

According to the structure of (1), when the lockup piston is fastened, the difference between the converter chamber and the lockup chamber is maintained until the pressure change rate calculated by the pressure change rate calculation unit reaches a predetermined value. The hydraulic pressure control solenoid valve is driven by the control signal that maximizes the pressure. Then, when the pressure change rate becomes equal to or lower than a predetermined value, the control signal returns to a predetermined control signal according to the rotation speed of the input / output element, and thereafter, the output element calculated based on the input / output speed ratio detected by the speed ratio detection unit. The solenoid valve for hydraulic pressure control is driven by the control signal that increases at a speed according to the torque.

As a result, the slip ratio of the lock-up clutch is maintained in the optimum state according to the driving condition. Further, the slip ratio of the lock-up clutch is optimal so as not to lose the torque of the output element.

Further, in (2), the control signal returned when the pressure change rate becomes equal to or lower than the predetermined value is determined based on the pressure value detected by the pressure detection unit. In (3), first, the torque capacity coefficient is obtained by referring to the first map from the speed ratio of the input / output elements detected by the speed ratio detection unit, and this is multiplied by the square of the rotation speed of the input element. Thus, the torque of the output element is obtained, and the increasing speed of the control signal is obtained from this torque with reference to the second map.

Further, in (4), the larger the magnitude of the torque of the output element is, the larger the control signal is, so that the engagement speed of the lockup clutch is increased.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an example of a case where the release pressure of the lockup clutch, that is, the release pressure is detected and controlled in the configuration of the present invention.

This embodiment is provided with a torque converter, a lockup clutch incorporated in the torque converter, a hydraulic circuit, and a control unit consisting of a microcomputer, which are basically the same as the conventional construction. The features of the present invention are implemented according to software embedded in the memory of the control unit.
Hereinafter, the configuration of each unit will be sequentially described.

<Torque Converter> Torque Converter 4
As shown in FIG. 2, the pump impeller 10 (input element), turbine runner 11 (output element), stator 12
It has three impellers.

The pump impeller 10 is driven by a crankshaft of an engine (not shown) via a converter cover 10a connected to the pump impeller 10. The turbine runner 11 is attached to a turbine hub 13, and the turbine hub 13 is connected to an input shaft (input shaft) 14 of the automatic transmission.

The stator 12 is attached to the hollow fixed shaft 16 shown in FIG. 2 via a one-way clutch 15. The hollow fixed shaft 16 is surrounded by a cylindrical shaft 17, and a hydraulic oil supply passage 18 is provided between the hollow fixed shaft 16 and the cylindrical shaft 17. Further, the hydraulic oil return passage 1 is provided between the input shaft 14 and the hollow fixed shaft 16.
9 are provided. Furthermore, the input shaft 14
A hydraulic oil passage 23 is provided through the center of the. The hydraulic oil supplied from the hydraulic oil supply passage 18 flows through the torque converter 4 and is then discharged from the hydraulic oil return passage 19.

<Lockup Clutch> The torque converter 4 is provided with a lockup clutch mechanism 1, and this lockup mechanism has a lockup piston 3 as shown in FIG. This lockup piston 3
Is an annular disc shape, the inner periphery of which is the turbine hub 13
It is slidably attached to the outer circumference.

The lockup piston 3 has a clutch facing 3a facing the inner surface of a converter cover 10a which is integral with the pump impeller 10. Then, a converter chamber 20 is defined between the lockup piston 3 and the turbine runner 11, a lockup chamber 21 is defined between the lockup piston 3 and the converter cover 10a, and the converter chamber 20 and the lockup chamber 21 are defined. Two
1 communicates with the outer circumference of the lockup piston 3. The hydraulic pressures in the converter chamber 20 and the lock-up chamber 21 are normally kept constant by a pressure-retaining valve (not shown) provided midway in the hydraulic oil flow passage from the hydraulic oil supply passage 18 to the hydraulic oil return passage 19.

The lockup piston 3 is further drivingly connected to the turbine runner 11 via a torsional damper 22. Then, the hydraulic pressure controlled by the lock-up control valve 24 built in the oil pump cover (not shown) (the engagement pressure acting in the direction of engaging the lock-up clutch: the apply pressure) is applied to the converter chamber 20. The pressure is the hydraulic pressure in the lockup chamber 21 (release pressure acting in the direction of releasing the lockup clutch:
When the pressure becomes larger than the release pressure), the lock-up piston 3 moves axially on the turbine hub 13, thereby connecting the converter cover 10a and the clutch facing 3a.

<Hydraulic Circuit> Here, the torque converter 4
A hydraulic circuit for control will be described with reference to FIGS.

As shown in FIGS. 3 and 4, the hydraulic circuit is
An oil pump 30 as a hydraulic source that supplies hydraulic pressure (line pressure) to various hydraulic devices, and a pressure regulator that distributes the hydraulic oil supplied from the oil pump 30 to the torque converter 4 and a hydraulic control device of a transmission (not shown). Valve 31, torque converter operating pressure supplied from the pressure regulator valve 31 to the torque converter 4 (hereinafter referred to as apply pressure or converter pressure)
Lock-up control valve 24 for controlling the lock-up control, and a lock-up solenoid (hydraulic pressure control solenoid valve) 2 for controlling the operation of the lock-up control valve 24.
5. Hydraulic pressure (line pressure) supplied from the oil pump 30
And a relief valve 35 for draining the hydraulic oil of the torque converter 4.

The hydraulic oil supplied from the oil pump 30 is supplied to the hydraulic oil supply passage 18 of the torque converter 4 via the pressure regulator valve 31. The hydraulic oil supplied from the hydraulic oil supply passage 18 passes through the pump impeller 10, rotates the turbine runner 11, and then drains from the escape valve 35 through the hydraulic oil return passage 19.

On the other hand, a part of the hydraulic oil that has passed through the turbine runner 11 reaches the lock-up chamber 21 via the converter chamber 20, and further passes through a hydraulic oil passage 23 passing through the center of the input shaft 14, and then, as shown in FIG. As shown in FIG. 2, it reaches the first port 24 a provided on the side surface of the lockup control valve 24.

The lock-up control valve 24 is provided with the first port 24a on the side surface of the cylinder-shaped valve body.
In addition, it has a second port 24b and a drain port 24c, a first control port 24f on one end face of the valve body, and a second control port 24g on the other end face.

Further, a slidable valve piston 24d is provided inside the valve body, and the first port 24a and the second port 24b are connected around the valve piston 24d by the movement of the valve piston 24d. Further, it has a communication groove 24h for selecting the connection between the first port 24a and the drain port 24c.

Further, the first control port 24f is connected to the first port 24a and the hydraulic oil passage 23 via a passage 24e.
The valve piston is moved to the side connecting the first port 24a and the drain port 24c by the hydraulic pressure applied to the first control port 24f.

A valve control passage 26 for applying a line pressure from the oil pump 30 is connected to the second control port 24g. When the line pressure is applied to the second control port 24g, the valve control passage 26 is connected to the first port 24a. The valve piston 24d moves to the side connecting with the second port 24b. The line pressure is applied to the second control port 24g by the valve control path 2
This is done by opening and closing the orifice of the drain path 29 branched from the middle of 6 by the lock-up solenoid 25. That is, when the movable plunger 25a of the lockup solenoid 25 shuts off the drain passage 29, the line pressure is applied to the second control port 24g, and the movable plunger 2
When 5a opens the drain passage 29, the line pressure is released from the drain passage 29. The degree of interruption of the drain path 29 of the movable plunger 25a is determined by the duty ratio of the applied voltage.

On the other hand, the line pressure supplied from the oil pump 30 is increased or decreased by being controlled by the line pressure solenoid 34. The configuration is performed by adjusting the opening degree of the orifice of the drain passage 34a, similarly to the control by the lockup solenoid 25. The lockup pressure (and the apply pressure) also increases / decreases in proportion to the increase / decrease in the line pressure.

<Control Unit> The lock-up solenoid is drive-controlled by a control unit 33 equipped with a microcomputer.

As shown in FIG. 1, the control unit 33 includes a lockup command section 40 for performing lockup control according to the running state of the vehicle, a control flag management section 41 for indicating the lockup control state, and a release pressure. To the lockup solenoid 25, the pressure detection unit 42 for detecting the state of the pressure change rate, the pressure change rate calculation unit 50 for calculating the change rate of the release pressure, the speed ratio detection unit 43 for calculating the input / output speed ratio of the torque converter 4. The solenoid valve control unit 44 for adjusting the engagement pressure (apply pressure) of the hydraulic oil supplied to the converter chamber 20 of the torque converter 4 by duty-controlling the applied voltage of
And. In addition, a map M1 that defines the relationship between the input / output speed ratio of the torque converter 4 and the torque capacity coefficient shown in FIG. 6 is stored in the memory of the control unit, and for controlling the lockup solenoid 25 shown in FIG. A map M2 defining the relationship between the duty ratio and the release pressure,
The map M3 that defines the relationship between the turbine torque and the duty ratio increasing speed shown in FIG. 8 and the flag management table 45 shown in FIG. 9 are stored.

The control flag management section 41 stores in the flag management table 45 a K flag (KFLG) indicating whether or not the lockup clutch is completely engaged, and a D flag (DFLG) indicating whether or not the gap of the lockup clutch is closed. ),
The state of the P flag (PFLG) for determining whether or not the release pressure has started to decrease is stored. When setting each flag, the content of the table 45 is set to 1.

The pressure detection unit 42 detects the release pressure by the release pressure sensor 49. Pressure change rate calculation unit 50
Receives the release pressure obtained from the pressure detection unit 42 and calculates the increase / decrease state and increase / decrease gradient of the release pressure. That is, the pressure detection unit 42 detects the release pressure Pt1 at a certain time point and the release pressure Pt2 after that, calculates Pt2-Pt1 to obtain the difference ΔP, and calculates Pt2 / Pt1 to calculate the increase / decrease degree of the release pressure. Calculate the (gradient). Then, when the release pressure starts to decrease, the P flag (PFLG) of the flag management table 45 is set to 1.

The speed ratio detector 43 detects the engine speed (N
e) is connected to a first sensor 47 for detecting (rotational speed of pump impeller) and a second sensor 48 for detecting the rotational speed (Nt) of the turbine runner 11, and is connected to the first and second sensors 4 and 4.
The input / output speed ratio (Nt / Ne) to / from the torque converter 4 is calculated from the information from 7, 48. The first sensor 47 for detecting the engine speed is provided on the crankshaft connected to the engine, and the second sensor 48 for detecting the speed (Nt) of the turbine runner 11 is the output shaft of the torque converter 4. It can be provided on the input shaft 14.

The solenoid valve control section 44 receives the speed ratio (Nt / Ne) information from the input / output speed ratio detecting means 41, and also refers to the maps of FIGS. 6, 7 and 8, and
With reference to the flag of FIG. 9, the duty ratio of the current voltage supplied to the lockup solenoid is changed according to the state of the torque converter.

<Operation of Embodiment> The operation of this embodiment will be described below.

<Unlocked> Normally, the line pressure from the oil pump 30 is supplied to the pressure regulator valve 3 at a constant duty ratio by the line pressure solenoid 34.
1, the applied pressure (converter pressure) is supplied from the pump impeller 10 to the converter chamber 20 via the turbine runner 11.

When the plunger 25a of the lockup solenoid 25 closes the orifice of the drain passage 29, the second control port 24 of the lockup control valve 24.
The control pressure Ps applied to g becomes equal to the line pressure PL, and moves the valve piston 24d leftward in the figure.

As a result, the lockup pressure PL / U in the lockup chamber 21 becomes equal to the converter pressure (apply pressure) in the converter chamber 20. Therefore, the lockup piston 3 is not pressed against the converter cover 10a, and the torque converter 4 transmits power in a so-called converter state.

<Lockup Operation> When it is necessary to reduce the loss due to so-called “slip” of the torque converter 4, a command from the control unit 33
The plunger 25a of the lockup solenoid 25 opens the orifice of the drain passage 29.

Then, since the control pressure Ps applied to the second control port 24g of the lockup control valve 24 becomes 0, the valve piston 24d moves to the right in FIG. 2 by the apply pressure received at the first control port 24f. Moving.
As a result, the first port 24a and the drain port are connected, and the hydraulic oil in the lockup chamber 21 is transferred to the hydraulic oil passage 23,
It is discharged from the drain port 24c via the first port 24a.

Therefore, the lockup pressure PL / U in the lockup chamber 21 becomes 0, and the lockup piston 3 is pressed against the converter cover 10a side by the apply pressure (converter pressure) in the converter chamber 20. As a result, the lockup piston 3 moves on the shaft on the turbine hub 13 toward the engine side, and the clutch facing 3a
Connects to the converter cover 10a. After that, the input element and the output element are directly connected, and the power of the engine is directly connected to the engine → converter cover 10a → clutch facing 3a → lockup piston 3 → turbine hub 13 → input shaft 14. It This state is called a lockup state.

Before the lockup, the hydraulic circuit is in the state shown in FIG. 3, and during the lockup operation, the hydraulic circuit is in the state shown in FIG. However, in FIGS. 3 and 4, unlike the case of FIG. 2, the lockup control valve 24 is adapted to perform a lockup operation when a line pressure is applied.

The above description is for general lockup control, but an example of how the lockup control according to the present invention changes the above general lockup control will be described below.

First, the engine speed, turbine speed, release pressure, etc. are read in as various information necessary for control (step 101). Next, the lockup command unit 40
It is checked whether or not a lockup on command is issued from (step 102). If no lockup on command is issued, the duty ratio to the lockup solenoid 25 is 0.
% (Step 107) and the lockup clutch is not engaged. If the lockup ON command is issued, the solenoid valve control unit 44 checks whether or not the K flag (KFLG) indicating whether or not the lockup clutch is completely engaged is set (step 103).

When the K flag (KFLG) = 1, that is, in the case of complete engagement, the solenoid valve control unit 44 determines that the duty ratio = 1.
The lockup clutch is held in a completely engaged state with the lockup clutch set to 00% (step 115). When the K flag (KFLG) is not set, the solenoid valve control unit 44 indicates the D flag (DF) indicating whether the gap of the lockup clutch is closed.
Check LG).

When the D flag is not set, the gap of the lockup clutch is not closed, so the solenoid valve control unit 44 sets the duty ratio to 100% so as to close the gap of the lockup clutch early (step). 12
0).

Next, the solenoid valve control unit 44 refers to the flag management table 45 and checks whether or not the P flag (PFLG) for determining whether or not the release pressure has started to fall is set (step). 105). If the P flag is not set, it means that the release pressure is in a state before it starts to decrease. Therefore, the pressure change rate calculation unit 50 subtracts the previous release pressure P0 from the current release pressure Pn and the difference is equal to or more than the predetermined value ΔP. It is determined whether or not it has decreased (step 106). When the release pressure difference is ΔP or less, it is regarded as within the release pressure fluctuation range, and the solenoid valve control unit 44
Precharge is continued (step 115). If the release pressure difference is ΔP or more, the release pressure has started to decrease, so P flag = 1 (step 108), and the process is skipped from step 105 to step 110 from the next time.

When the release pressure decreases, the pressure change rate calculation unit 50 calculates the decrease gradient of the release pressure (step 1
10) If the value is greater than or equal to the predetermined value, the release pressure has not been drastically reduced, so the solenoid valve control unit 44 continues the duty = 100% (step 115).

When the release pressure decrease gradient becomes equal to or less than the predetermined value, the gap of the lockup clutch is closed and the engine speed starts to decrease. If the speed at which the hydraulic oil remaining in the release chamber is exhausted from here is too fast, a lock-up engagement shock will occur. Therefore, the value D1 (%) in which the duty ratio is returned from 100% and the subsequent ascending speed ΔD are made appropriate. There is a need. Therefore, the solenoid valve control unit 44 obtains the values of D1 and ΔD from the correlations shown in FIGS. 6, 7, and 8 (step 112).

First, for D1, the duty ratio corresponding to P _R is obtained from the current read value of the hydraulic pressure sensor in FIG. If the duty ratio value D1 is held, the release pressure will maintain the current value.

However, in order to engage the lockup clutch, it is necessary to increase the duty ratio. For the increasing speed, the speed ratio detection unit 43 calculates the speed ratio (output rotation speed / input rotation speed) from the input / output rotation speed of the torque converter, and the electromagnetic valve control unit 44 receiving the result calculates the torque ratio of The torque capacity coefficient τ is calculated from the converter performance map, and the turbine torque Tt is calculated by multiplying the square of the input rotation speed (engine rotation speed Ne) (Tt = τ × Ne).
² ) and refer to ΔD in FIG.

When entering the duty ratio increasing region, the control flag management unit 41 sets the D flag and sets DFLG = 1 (step 114). Since this flowchart is executed every 10 ms by the interruption of the timer, DFLG
When the program is executed next time after = 1,
The process jumps from step 104 to step 111 to increase the duty ratio by ΔD. Then, the solenoid valve control unit 44 determines whether or not the duty ratio after the increase reaches 100% (step 116), and if it reaches 100%, the 100% state is held (step 117) and the engagement is completed. The control flag management unit 4 indicates that the control is completed.
By 1, the K flag (KFLG) is set to 1 (step 1
18).

When the K flag becomes 1, the process jumps from step 103 to step 115 from the next time, and the duty ratio of 100% is held.

If the lockup command is no longer present, the routine jumps from step 102 to step 107, the lockup is released with a duty ratio of 0%, and the control flag management unit 41 causes the K flag (KFLG) and the D flag (DFL).
G) and P flag (PFLG) are set to 0 in case the lockup command is issued at the next opportunity.

FIG. 1 is a time chart showing the above process.
It becomes like 0. In the control of the present embodiment, as shown in FIG. 10, the control is performed by looking at the release pressure, so the change in the control hydraulic pressure (release pressure) is locked up smoothly in the shortest time and without causing a shock. It becomes possible to engage the clutch.

Of course, if the feedback pressure is controlled in the same manner as in the conventional example after the release pressure gradient becomes small (when the engine rotation change starts), the engine rotation can be smoothly reduced and the engagement can be performed without shock. Even in the duty ratio increasing control at a constant speed according to the load as in the embodiment, since the facing gap is already clogged (the duty ratio and the engine rotation change are not delayed), the engine is controlled by this control. The rotation is gently reduced, and shock-free engagement is possible.

The fact that the clearance of the lock-up clutch is clogged (determination of the timing of dropping the duty ratio value from 100% to D1) can be detected even by a change in the engine speed, but the speed ratio is 1.0. When it is close to, the difference between the engine speed and the turbine speed is small, and it is buried in the engine speed fluctuation, and it is difficult to actually meet all the conditions.

<Other Embodiments> In the above embodiments,
Although the control is performed according to the change in the release pressure of the lockup clutch, that is, the release pressure, the same control as in the first embodiment is performed according to the change in the differential pressure between the engagement pressure (apply pressure) and the release pressure (release pressure) of the lockup clutch. It can be carried out.

[0069]

As described above, according to the present invention, (a) the input element that is rotationally driven by the engine, and (b) that the driven element is driven and rotated by the fluid that flows as the input element rotates, (C) In the fluid between the output element connected to the input shaft of the automatic transmission and the input / output element, the input element and the output element are fastened or released by the differential pressure of the fluid hydraulic pressure received on both sides. (D) For hydraulic pressure control capable of controlling hydraulic pressure in either one of the converter chamber and the lockup chamber, which are arranged on both sides of the lockup piston with the lockup piston interposed therebetween, or the differential pressure between these chambers. Torque with a lock-up clutch having a solenoid valve and (e) a solenoid valve control section for outputting a control signal to the hydraulic control solenoid valve for fastening the lock-up piston in accordance with the traveling state of the vehicle. In the converter control device, (f) a pressure detection unit that detects the hydraulic pressure of either the converter chamber or the lockup chamber or the differential pressure between these chambers; and (g) the pressure detected by the pressure detection unit. From the pressure change rate calculation unit for calculating the change rate of this pressure from,
(H) a speed ratio detection unit that detects a speed ratio of the input / output elements, and the solenoid valve control unit, when the lockup piston is fastened, the pressure change calculated by the pressure change rate calculation unit. A control signal that maximizes the differential pressure between the converter chamber and the lockup chamber is output until the rate reaches a predetermined value, and when the pressure change rate becomes a predetermined value or less, a predetermined value according to the rotation speed of the input / output element is output. After that, the control signal is output to the hydraulic pressure control solenoid valve, which is increased at a speed corresponding to the torque of the output element calculated based on the input / output speed ratio detected by the speed ratio detection unit. Therefore, various operating conditions (speed ratio, accelerator depression, etc.)
Also in the above, the effect that the lock-up clutch engagement time is short and stable without causing an engagement shock, and the fuel efficiency can be effectively improved is obtained.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an outline of the present invention.

FIG. 2 is a diagram showing an example of a torque converter.

FIG. 3 is a diagram showing a hydraulic circuit when not locked up.

FIG. 4 is a diagram showing a hydraulic circuit at lockup.

FIG. 5 is a flowchart showing an example of control according to the embodiment of the present invention.

FIG. 6 is a map that defines the relationship between the input / output speed ratio of the torque converter and the torque capacity coefficient.

FIG. 7 is a map defining the relationship between the duty ratio and the release pressure for controlling the lockup solenoid.

FIG. 8 is a map that defines the relationship between output element torque and duty ratio increase speed.

FIG. 9 is a diagram showing a flag management table.

FIG. 10 is a time chart diagram showing a control example according to an embodiment of the present invention.

FIG. 11 is a time chart diagram showing a conventional control example.

[Explanation of symbols]

3 ... Lock-up piston, 3a ... Clutch facing, 4 ... Torque converter, 10 ... Pump impeller, 10a ... Converter cover, 11 ... Turbine runner, 12 ... Stator, 13 ... Turbine hub, 14 ... Input shaft (input shaft), 15 ... One-way clutch, 16 ... Hollow fixed shaft, 17 ... Cylindrical shaft, 18 ... Hydraulic oil supply passage, 19 ... Hydraulic oil return path, 20 ... Converter chamber, 21 ... Lockup chamber, 22 ... Torsional damper, 23 ... Hydraulic oil passage, 24 ... Lockup control valve, 24a・ ・ ・ First port, 24b ・ ・ ・ Second port, 24c ・ ・ ・ Drain port, 24d ・ ・ ・ Valve piston, 24e ・ ・ ・ Passage, 24f ・ ・ ・ First control port 24g ... second control port, 24h ... communication groove, 25 ... lock-up solenoid (solenoid valve for hydraulic control), 25a ... plunger, 25a ... movable plunger, 26 ... valve Control path, 29 ... drain path, 30 ... oil pump, 30 ... oil pump, 31 ... pressure regulator valve, 31 ... pressure regulator valve, 33 ... control unit, 34 ... ..Line pressure solenoid, 34a ... Drain passage, 35 ... Valve, 40 ... Lockup command section, 41 ... Control flag management section, 42 ... Pressure detection section, 43 ... Speed Ratio detector, 44 ... Electromagnetic valve controller, 45 ... Flag management table, 47 ... Engine speed sensor, 48 ... Turbine speed sensor Sensor, 49 ... Release pressure sensor, 50 ... Pressure change rate calculation unit

Claims (4)

[Claims] 1. An input element that is rotatably driven by an engine, and (b) an output element that is driven and rotated by a fluid that flows with the rotation of the input element and that is connected to an input shaft of an automatic transmission. (C) a lock-up piston which is in the fluid between the input and output elements, and which engages or disengages the input element and the output element by the differential pressure of the fluid pressure received on both sides; and (d) the lock-up piston. Solenoid valve for hydraulic control that can control the hydraulic pressure in either the converter chamber or lock-up chamber or the differential pressure between these chambers, which are placed on both sides of the solenoid valve, and (e) depending on the running condition of the vehicle. And a solenoid valve control section for outputting a control signal to the hydraulic control solenoid valve for engaging the lock-up piston with a lock-up clutch. The pressure detection unit that detects the hydraulic pressure of either the converter chamber or the lockup chamber or the pressure difference between these chambers, and (g) the rate of change of this pressure is calculated from the pressure detected by the pressure detection unit. A pressure change rate calculation unit; and (h) a speed ratio detection unit that detects a speed ratio of the input / output elements, wherein the solenoid valve control unit calculates the pressure change rate when the lockup piston is fastened. A control signal that maximizes the differential pressure between the converter chamber and the lockup chamber is output until the pressure change rate calculated by the unit reaches a predetermined value, and when the pressure change rate becomes a predetermined value or less, an input / output element To a predetermined control signal corresponding to the number of revolutions of the hydraulic pressure control electromagnetic wave, and thereafter a control signal that increases at a speed corresponding to the torque of the output element calculated based on the input / output speed ratio detected by the speed ratio detection unit Output to the valve A control device for a torque converter with a lockup clutch. 2. The control signal returned when the rate of pressure change in the solenoid valve control unit becomes equal to or lower than a predetermined value is determined based on the pressure value detected by the pressure detection unit. 1. A control device for a torque converter with a lockup clutch according to 1. 3. When obtaining the increasing speed of the control signal according to the torque of the output element in the solenoid valve control section,
3. A map defining a relationship between a speed ratio of an input / output element and a torque capacity coefficient, and a map defining a relationship between a torque of an output element and an increasing speed of a control signal are used. A control device for a torque converter with a lock-up clutch as described above. 4. The increasing speed of the control signal according to the torque of the output element in the solenoid valve control unit increases as the torque of the output element increases. A control device for a torque converter with a lock-up clutch as described above.