JPH02203072A - Slip control device for fluid coupling - Google Patents

Abstract

PURPOSE:To prevent a shock or a sudden increase of a rotary speed by controlling connecting force of a lockup clutch in a decreasing direction from the point of time of a predetermined operation region, when a transfer is detected of the lockup clutch to its complete release operation region. CONSTITUTION:A slip control device for a fluid coupling, in a predetermined operation region judged from an engine load and a drive system speed, controls connecting force (slip rate) of a lockup clutch to a predetermined value. In this predetermined operation region, when a detecting means detects a transfer from the predetermined operation region to an operation region where the lockup clutch is completely released, a control means starts from the predetermined operation region a control of the connecting force to its decreasing direction of the lockup clutch. Thus, a shock or a sudden increase of a rotary speed can be prevented of the lockup clutch when it is released.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a slip control device for a fluid coupling equipped with a lock-up clutch mechanism used, for example, in automatic transmissions for automobiles. The present invention relates to a slip control device for controlling slippage by controlling fastening force.

(Prior Art) In fluid couplings (hereinafter referred to as torque converters) used in automatic transmissions for automobiles, in order to reduce the deterioration of engine fuel efficiency caused by so-called slippage of the torque converter, a torque increasing effect is used. In a predetermined operating range in which the torque converter does not require a shift shock absorption function, a lock-up clutch may be provided to directly connect the input member and output member of the torque converter.

By the way, if this locking clutch is engaged and the torque converter and output components are directly connected, engine vibrations will be directly transmitted to the transmission, especially in the low engine rotation range, and the ride quality of the vehicle will deteriorate. A problem occurs. Furthermore, if the lock-up clutch is released in a relatively wide range on the low engine speed side in order to cope with this problem, the fuel efficiency reducing effect of the lock-up clutch will not be effectively utilized.

Therefore, as shown in Japanese Patent Laid-Open No. 61-52427, for example, the lock-up clutch is controlled to be partially engaged and slipped in a predetermined operating range, compared to the case where the lock-up is completely released. This prevents engine vibration from being transmitted to the transmission while reducing deterioration in fuel efficiency. In a torque converter that performs such slip control, the first control region is
As shown in Figure 0A, there is a slip control region where the above-mentioned slip control is performed, a converter region where the lock-up clutch is completely released and the converter operates, and a lock-up region where the lock-up clutch is engaged.

By the way, the following problems have been pointed out with this slip control. When the accelerator is gradually depressed while driving in the slip control region, the slip region shifts to the converter region (transfers from A to B in Fig. 10A). The opening rate is approximately 1.5/8. Now, when shifting to the converter region, the coupling force of the lock-up clutch is weakened, so the engine speed suddenly increases as shown in FIG. 10B. Since this sudden increase occurs even in response to the slightest accelerator operation by the driver, it feels very strange.

On the other hand, as an example of a torque converter that performs the same slip control, there is, for example, Japanese Patent Laid-Open No. 57-33253. In this patent application, the amount of slip in the slip control region is finely changed, and the amount of slip is set to be large in the converter region.

(Problem to be Solved by the Invention) When trying to prevent a sudden increase in engine speed when transitioning to the above-mentioned converter region, the following should also be considered.
It will be done. That is, as shown in FIG. 11, feedback control is performed in the slip control region, and when the shift to the converter region occurs, the duty of the duty solenoid that controls the amount of slip of the lock-up clutch is gradually reduced.

However, according to the inventor of the present application, even with this method, it was not possible to suppress the increase in engine speed to such an extent that the user does not feel any discomfort when shifting to the converter. In addition, in the above-mentioned Japanese Patent Application Laid-Open No. 57-33253, the slip amount is set to be larger in the slip region as it approaches the converter region, so even when there is no transition from the slip region to the converter region, a large slip exists. Therefore, it cannot be said to be effective in improving fuel efficiency.

Therefore, the present invention was proposed in order to eliminate the drawbacks of the above-mentioned conventional examples.The purpose of the present invention is to propose a slip control device for a fluid coupling that achieves both improved fuel efficiency and suppressed shock when lock-up is released. be.

(Means and operations for achieving the object) As shown in FIG. 1, the configuration of the present invention for achieving the above object is as follows: In a slip control device for a fluid coupling having a lock-up clutch mechanism that controls the fastening force to a predetermined value, the transition from the predetermined operating range to an operating range in which the lock-up clutch is completely released is as follows:
The present invention further comprises a means for detecting within the predetermined operating region, and a means for receiving the output of the means to start controlling the engagement force of the lock-up clutch in a decreasing direction from the predetermined operating region. Features.

That is, when a shift is detected from a predetermined operating state range in which the lock-up clutch is in a partially engaged state to an operating range in which the lock-up clutch is completely released, the engagement force of the lock-up clutch is reduced to this predetermined state. is controlled in the downward direction from the point in the operating range of .

(Example) An example in which the present invention is applied to a torque converter for an automobile will be described below with reference to the accompanying drawings.

<Configuration of Torque Converter> First, the structure of the torque converter and its control hydraulic circuit will be explained with reference to FIG. A pump 4 rotates integrally with the engine output shaft 2.
A turbine 5 is rotatably provided on the other side of the case 3 so as to face the pump 4, and is rotationally driven via hydraulic oil by the rotation of the pump 4. a stator 6, which is interposed between the turbine 5 and the case 3, and which increases the torque when the speed ratio of the turbine rotation speed to the pump rotation speed is below a predetermined value; and a lock-up clutch 7, which is interposed between the turbine 5 and the case 3. has.

The rotation of the turbine 5 is outputted by a turbine shaft 8 and inputted to a speed change gear mechanism (not shown), and the lock-up clutch 7 is connected to the turbine shaft 8 and is connected to the case 3. When fastened, the engine output shaft 2 is connected to the engine output shaft 2 through the case 3.
and the turbine shaft 8 are directly connected.

Further, hydraulic oil is introduced into the torque converter 1 through a main line 9 led from an oil pump (not shown) through a lock-up valve 10 and a converter inline 11, and the pressure of this hydraulic oil is The lock-up clutch 7 is always urged in the engagement direction, and a lock-up release line 13 led from the lock-up valve 10 is connected to the space 12 between the clutch 7 and the case 3. When hydraulic pressure (release pressure) is introduced into the space 12 from the line 13, the lock-up clutch 7 is released. Further, a converter outline 16 is connected to the torque converter 1 to send hydraulic oil to an oil cooler 15 via a pressure holding valve 14.

On the other hand, the lock-up valve 10 has a spool 10a.
and a subring lOb that urges this to the right in the drawing, and a pressure regulating boat 10d and a drain boat Roe to which the main line 9 is connected to both sides of the boat 10c to which the lockup release line 13 is connected. is provided. Further, a control line 17 for applying pilot pressure to the spool 10a is connected to the right end of the valve 10 in the drawing, and this control line 1
A duty solenoid valve 19 is installed in a drain line 18 branched from 7.

This duty solenoid valve 19 repeatedly turns on and off at a duty rate according to an input signal to open and close the drain line 18 in extremely short cycles, thereby adjusting the pilot pressure in the control line 17 to correspond to the duty rate. Adjust to value. Then, a force is applied to the pilot 10a in a direction opposite to the biasing force of the spring 10b, and a release pressure in the lock-up release line 13 is applied to the spool 10a in the same direction as the biasing force of the spring 10b. The spool 10a moves due to the force relationship between these oil pressures or biasing forces, and the lockup release line 13 is connected to the main line 9 (pressure regulating boat 10).
d) or by communicating with the drain boat 10e,
The lockup release pressure is controlled to a value corresponding to the pilot pressure, that is, the duty rate of the duty solenoid valve 19.

Here, when the duty rate is at its maximum value, the amount of drain from the control line 17 is at its maximum, and the pilot pressure or release pressure is at its minimum, so that the lock-up clutch 7 is completely engaged. Further, when the duty rate is at a minimum value, the drain amount is at a minimum, and the pilot pressure or release pressure is at a maximum, so that the lock-up clutch 7 is completely released. At a duty rate between the maximum value and the minimum value, the lock-up clutch 7 is in a slip state, and by adjusting the release pressure in accordance with the duty rate in this state, the amount of slip of the lock-up clutch 7 is controlled. It is now possible to do so.

Next, the electric circuit that controls the slip amount of the lock-up clutch 7 will be explained. As shown in FIG. 21, and a throttle sensor 22 that detects the throttle opening θ of the engine.
and signals from a gear position sensor 23 that detects the gear position G of the automatic transmission, an engine rotation sensor 24 that detects the engine rotation speed Nt, and a turbine rotation sensor 25 that detects the rotation speed Nt of the turbine shaft 8. is now entered.

Then, the CPU 20 controls the duty solenoid valve 19 based on the signals from the sensors 21 to 25.
The duty ratio is calculated, and the slip control of the torque converter l, that is, the slip amount of the lock-up clutch 7 is controlled according to the flowchart shown in FIG.

<Principle of control of embodiment> The principle of slip control of this embodiment will be explained using FIG. 4.

In order to reduce fuel consumption in the slip control operation region, when staying in the slip control operation region, as much as possible,
It is necessary to set the amount of slip with emphasis on fuel efficiency. In addition, in order to suppress the shock when transitioning from this slip control operation area to the converter area, it is necessary to increase the amount of slip only when transitioning from this slip control operation area to the converter area. It is necessary to reduce the difference in the transmitted torque from when the lock-up clutch is completely released when the lock-up clutch actually moves to the converter region by reducing the engagement force to a greater extent. In order to do this, it is necessary to detect in advance that the slip control operation area is about to shift from the slip control operation area to the converter area. In this embodiment, in principle, this is done by accelerator opening (
That is, detection is attempted when the rate of change in the vehicle speed V with respect to the change in the throttle opening degree θ), that is, d θ d T is large (or negative). This indicates that the slope of the change in the operating region indicated by the arrow in FIG. 4 becomes steeper. This is because if this differential value is small, there is a possibility that the slip control region will shift to the lockup region. In other words, even if the throttle opening degree θ changes in the opening direction, that is, even if the engine load increases, when the vehicle speed (or engine speed) does not increase, the above differential value becomes large and soon The principle of the control of this embodiment is to increase the slip amount upon determining that the shift is to the converter region.

In principle, it is possible to detect in advance that the slip control will shift to the converter region by examining the above-mentioned differential value. The method of increasing this detection accuracy will be explained in connection with the control flowchart of FIG. 6.

Figure 5 is a timing chart that specifically shows how driving changes due to slip control, which will be explained below.The data shown are engine speed NA, duty value, and vehicle speed. Time change d
V/d t and throttle opening θ. Moreover, the case where the shift from the slip control operating range to the converter range is particularly explained. The outline of the control shown in FIG. 6 will be explained with reference to FIG. In FIG. 5, it is assumed that the converter is initially in the slip control region and is feedback-controlled in this region. That is, the duty D is feedback-controlled so that the actual slip amount converges to the target slip amount. The accelerator was stepped on, and furthermore,
When a shift from the slip control region to the converter region is detected in the near future, the duty D that controls the engagement force of the lock-up clutch is gradually decreased in the direction of decreasing the engagement force. Note that this gradual decrease is not enough to completely release the lock-up clutch. When the converter region is completely entered (θ=t, 5/8), the duty D is gradually decreased until the lock-up clutch is completely released. In this way, it is possible to both improve fuel efficiency and reduce shock when transitioning to the converter region.

Details of Control Procedure> FIGS. 6A to 6D are flowcharts showing the control procedure of the embodiment. FIG. 6A shows the main routine for slip control, and FIGS. 6B to 6D show each subroutine used in the main routine. Note that this flowchart is for calculating the duty rate, and the duty rate is actually pulse width modulated and output to the duty solenoid 19 by the CPU.
Since this pulse width modulation is well known, its explanation will be omitted.

Now, in step S2 of FIG. 6A, the vehicle speed ■.

Throttle opening degree θ, carrot rotation speed Ng, turbine rotation speed NT, and shift position G are read from each sensor. In step S4, it is determined from the vehicle speed V and the throttle opening θ, according to the characteristics shown in FIG. 7, whether the current driving region is in the slip control region.

In FIG. 7, the slip control region is indicated by 11, the lock-up region is indicated by 11, and the converter region is indicated by III.
It is indicated by. Incidentally, FIG. 7 shows a slip control region I, a lockup region II, and a converter region III at each shift position.

If the current operating range is in the converter region or in the lock-up region, in step 328, well-known lock-up control or converter control (subroutine L not shown) is performed.
U CN VT ). Since this LUCNVT is well known, its explanation will be omitted.

When it is determined in step S4 that the current operating range is in the slip control range, the control proceeds to step S6, and in step S6, slip amount feedback control (FDBK) is performed.
Then, in step S8, control (SUBVTH) is performed to calculate judgment data for changing the driving range.

Details of subroutine FDBK are shown in FIG. 6B, and details of subroutine S tJ B V T H are shown in FIG. 6C.

The details of the feedback control will be explained according to FIG. 6B. In step S30, step S2 or step S
Engine speed NE and turbine speed N read at 52
The slip amount N is determined from the difference with T. Step S3
2, this actual slip amount Ns and target slip amount N0
Calculate the deviation ΔN.

ΔN”Ns N.

In step S34, control parameters A and B (constants or variables) are determined, and a feedback amount U is calculated.

U=AXΔN+BXΔN In step 328, the duty correction amount Δdr corresponding to the feedback fiU is obtained from the microprocessor shown in FIG. 8, and the correction Δdr is added to the duty ratio.

D=D+Δdr Next, in step S40, the slip amount deviation is saved for the next calculation.

ΔN'=ΔN Step S42 is for PAUSE to execute feedback control at predetermined time cycles and also to allow the CPU 20 to execute other control routines.

The subroutine 5UBVTH will be explained with reference to FIG. 6C. In step S52, similarly to step S2, the vehicle speed ■ and the throttle distance θ are determined.

Engine speed Ng, turbine speed N? , gear shift position G
Read. This is because steps 86 to S24 shown in FIG. 6A are repeated in a loop, so that control can be performed using the latest data in each loop. In step S52, the time change in vehicle speed (dV/dt) and the time change in throttle opening (d
θ/dt). In step S54, the amount of change Δθ between the previously measured throttle opening θ′ and the currently measured throttle opening θ is calculated.

Δθ=θ−θ゛Then, in step S56, the current θ is saved for the next calculation. Control then returns to the main routine.

Returning to step SIO of the main routine in FIG. 6A, explanation will now be given. Here, the magnitude of the change amount Δθ in the throttle opening degree and the predetermined value δ(>O) is compared. Also, step S
In step 12, the time change in throttle opening (dθ/dt) is compared with a predetermined value t= (>0). Step SIO,
If it is determined in S12 that "(2nd dt>c"), it is determined that there is a possibility that the slip control region has entered the converter region, and the control proceeds to step 314 and subsequent steps.

On the other hand, if step S10. S12, 80≦6
Alternatively, if it is determined that dθ/dt≦ε, the process returns to step S6 and feedback control of the slip amount is continued.

Step S10. If it is determined in S12 that the condition is 1""' and that there is a possibility that the slip control region is progressing from the slip control region to the converter region, step 3 is performed.
The loop from step S14 to step S24 is repeated.

In this loop, if it is determined that the operation is definitely heading towards the converter region (step S
In step 18, Y E S ) performs control such as the gradual reduction control of the duty rate explained in FIG. The loop from step S14 to step S24 is exited when it is detected in step S14 that the system has actually transitioned from the slip control region to the lock-up region or the converter region (No in step S14), or when step S1
6, the time change dθ/dt of the throttle opening is not greater than “0”.

The loop from step 314 to step S24 will be explained in detail. If it is determined in step S14 that the engine is still in the slip control region based on the various information read in step S52, it is determined in step S16 whether the time change dθ/dt in throttle opening is positive or negative. If it is negative, the throttle is in the closing direction and there is no transition to the converter region, so the process returns to step S6 and changes to feedback control. That is, if the accelerator is released while the duty D gradually decreasing control is being executed, the feedback control is returned to.

If it is detected in step S16 that the accelerator is being depressed, that is, if it is determined that the engine load is increasing, the process proceeds to step S18, where the temporal change in vehicle speed (dV/
Check whether dt) is . If this time change is less than "O", it means that the vehicle speed has not increased even though the engine load has increased, so it is determined that the transition to the converter region is certain. Proceeding to step S20, the duty rate is gradually reduced as follows: D=D-Δd0.

Here, the above formula will be explained. The reason why the determination in step S18 is YES is because the determination in step S16 is YES, so that the slope indicated by the rate of change in throttle opening with respect to five changes in vehicle speed is It means negative. That is, This means that a transition from the current slip control region to the converter region has been definitely detected.

If No in step S18, step S2
Gradual decrease control of 0 is not performed.

In step S22, the latest data such as vehicle speed ■ is collected. PAUSE in step S24 is provided to guarantee the time interval of gradual reduction control.

While executing the loop from step 314 to step S24,
When it is detected that the slip control area is actually exceeded,
The control proceeds from step S14 to step 526 (subroutine LUCNVTA I L). Leaving the slip control region means either a transition to the converter region or a transition to the lockup region. Step 326 sub-rune LUCNVTA I L (
7) Details are shown in Figure 6D.

In FIG. 6D, if it is determined in step S60 that the area after the transition is a converter area, steps S68 to
In the loop of step S72, the lock-up on the duty rate is completely released or 1. , the gradual decrease is controlled until . The situation at this time is shown in FIG. 9(a).

If it is determined in step S60 that the area after the transition is the lock-up area, the duty rate is gradually increased until the lock-up is fully engaged, in a loop from step 862 to step S66. do.

The situation at this time is shown in FIG. 9(b).

The purpose of performing such gradual decrease control or gradual increase control is to reduce shock.

<Effects of Examples> In this way, the following effects can be obtained from the above embodiments. That is, the transition from the slip region I to the converter region can be reliably detected at the time the vehicle is in the slip control region.

Therefore, when such a detection is performed, the amount of slip can be increased in advance in the slip control region, and the shock and discomfort caused by a sudden increase in engine speed when shifting to the converter region is reduced. Specifically, as shown in FIG. 5, the engine speed rises smoothly.

In addition, since the transition from slip region I to converter region can be reliably detected at the time of slip control region I, slip control that emphasizes fuel efficiency is performed in driving conditions where it is determined that there will be no transition. This contributes to improving fuel efficiency.

<Modifications> The present invention can be modified in various ways without departing from the gist thereof.

That is, in step S18 of the above embodiment control, the duty D is gradually decreased when the time rate of change of the vehicle speed is "O" or less, but as explained in connection with FIG. Since the present invention is applicable when the rate of change in throttle opening is large, step S18
You can use instead of .

For more precise control, the accelerator opening θ
and the rate of change dθ/dt, find the predetermined acceleration β,
That is, β=f(θ, dθ/1), and if dV/dt≦β, the above control may be executed.

(Effects of the Invention) As explained above, the fluid coupling slip control device of the present invention is capable of controlling the fastening force to a predetermined value in a predetermined operating range determined based on the engine load and drive system rotation speed. In a slip control device for a fluid coupling having a lock-up clutch mechanism, means for detecting, within the predetermined operating region, a transition from the predetermined operating region to an operating region in which the lock-up clutch is completely released; The present invention is characterized by comprising means for receiving the output of the means and for starting to control the engagement force of the lock-up clutch in a decreasing direction from the predetermined operating range.

Therefore, when a transition from a predetermined operating state range in which the lock-up clutch is in a partially engaged state to an operating range in which the lock-up clutch is completely released is detected, the engagement force of the lock-up clutch is reduced to this predetermined state. It will be controlled in a downward direction from the point in time in the operating region. Therefore, a shock or a sudden increase in rotation when the lock-up clutch is released is prevented. Furthermore, since the amount of slip is increased only when a shock or sudden increase in rotation is to be prevented, the amount of slip during normal times can be reduced, contributing to improved fuel efficiency.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the present invention in detail, Fig. 2 is a sectional view of the torque converter and hydraulic circuit used in the embodiment, Fig. 3 is a block diagram of the control circuit of the embodiment, and Fig. 4 is the embodiment. Figure 5 is a timing chart explaining the control operation of the embodiment, Figures 6A to 6D are flowcharts of the procedure related to the control of the embodiment, and Figure 7 shows the operating range of the embodiment. Fig. 8 is a diagram showing the conversion characteristic from the feedback amount to the duty correction amount used in the embodiment, and Fig. 9 is a timing diagram illustrating the duty change when the slip control region is exceeded in the embodiment. The charts, FIG. 10A, FIG. 10B, and FIG. 11 are diagrams explaining the drawbacks of the prior art. In the figure, ■...Torque converter, 2...Engine output shaft,
8...Turbine shaft, 1o...Duty solenoid valve for lockup, 20...CPU, 24
．． 25...Engine rotation sensor, turbine rotation sensor.

Claims (1)

[Claims] (1) In a slip control device for a fluid coupling having a lock-up clutch mechanism that controls the engagement force to a predetermined value in a predetermined operating range determined based on the engine load and drive system rotation speed, the above-described predetermined means for detecting, within the predetermined operating range, a transition from the operating range to the operating range in which the lock-up clutch is completely released; and receiving the output of the means;
A slip control device for a fluid coupling, comprising means for starting to control the lock-up clutch in a decreasing direction from the predetermined operating range.