JPH04290675A - Tightening force controller for fluid coupling - Google Patents

Abstract

PURPOSE:To prevent the generation of the uncomfortableness due to the reduction of the engine revolution in the transition period by detecting the change of the operation state of a vehicle from the operation state where the control by the first control means is unnecessary to the operation state where the control is necessary, stopping the first control means for a prescribed time and carrying out slip control so that the number of engine revolution becomes equal to an aimed value. CONSTITUTION:Each signal of a car speed sensor 21, throttle sensor 22, shift stage sensor 23, engine revolution speed sensor 24, and a turbine revolution sensor 25 is inputted into a CPU 20, and the control for a lock-up clutch 7 is carried out by calculating and outputting the duty ratio D of a duty solenoid valve 19 on the basis of these signals. In the slip rate control region in the transition from the converter region to the lock-up operation region, the initial stage in which the slip control shifts from ON to OFF, the duty ratio is feedback-controlled so that the engine revolution speed converges to an aimed value.

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 controlling the fastening force of a fluid coupling used primarily in automatic transmissions for automobiles.

0002

[Prior Art] In torque converters used in automobile transmissions, in order to reduce the deterioration of engine fuel efficiency caused by so-called slippage of the torque converter, torque increasing effects, shift shock absorbing effects, etc. are used. In operating regions where this is not required, a lock-up clutch is provided to directly connect the engine output to the input/output components of the torque converter. In an automatic transmission equipped with such a lockup, there is a so-called "lockup operating region" where the slip ratio (the ratio of the input rotational speed to the torque converter to the engine rotational speed) in the lockup clutch is minimum, and a slip There is a "slip control operating region" in which the slip ratio is controlled to a target value, and a so-called "converter operating region" in which the slip ratio is maximized (slip control is turned off).

This slip rate is controlled by the low/high hydraulic pressure applied to the lock-up clutch chamber, which is controlled by the long/short opening/closing time of the duty solenoid (large/small duty ratio). Ru. Generally, the higher the duty ratio, the lower the oil pressure value and the more firmly the lockup clutch is engaged. When shifting from the converter operating region to the lock-up operating region or the slip control operating region, that is, from the operating region where the slip control is off to the operating region where the slip control is on or the lock-up operating region. , there is a concern about transient torque shock. To solve this problem, for example, Japanese Patent Application Laid-open No. 159466/1983 attempts to solve this problem by intermittent engagement of the lock-up clutch and sequentially variable control of the duty ratio from 0% to 100%. There is. That is, in this prior art, during the transient period, the duty ratio is gradually decreased at constant time intervals by feedforward control.

0004

SUMMARY OF THE INVENTION FIG. 1 illustrates the problems of the prior art described above. Two graphs are shown in FIG. 1, and in both graphs, the horizontal axis is time. Further, the vertical axis represents the engine rotation speed (broken line) and the turbine rotation speed (solid line), or the duty ratio. In Figure 1, the graph showing the change in duty ratio over time changes from 0% to 1% in the ↓ direction.
It is set as 00%.

As mentioned above, in the prior art, when the slip control transitions from the stop state to the start state,
By linearly changing the lock-up engagement state, that is,
Feedforward control of duty ratio (Fig. 1 shows F
However, in actual lock-up clutch mechanisms, the relationship between clutch capacity and duty ratio is not proportional, so the duty ratio is not linearly controlled. There is a point (D0 in FIG. 1) where the clutch capacity suddenly increases even if the clutch capacity is decreased to . After this point,
Since the lock-up clutch is relatively firmly engaged, the turbine speed increases, but the engine speed decreases. After this state of decrease in engine speed continues for a while, when the slip rate approaches a predetermined value, a shift is made to feedback control of the slip rate, and the engine speed increases. However, in any case, the reduction in vehicle speed for a certain period of time after the above-mentioned point D0 feels strange to the driver. Furthermore, it is difficult to uniquely determine the point D0 because it actually changes depending on the driving conditions (engine output torque, road surface slope). This means that during the period in which the feedforward control of the duty ratio is performed,
This means that it is difficult to eliminate the above-mentioned discomfort by changing the mode of feedforward control (for example, changing the reduction rate of the duty ratio).

Therefore, the present invention provides a method for fastening a fluid coupling that can prevent the occurrence of discomfort due to a decrease in engine rotation during the transition period after starting control of the fastening force of the fluid coupling, regardless of the running condition of the vehicle. The purpose is to provide a force control device.

[0007]

Means for Solving the Problems In order to achieve the above object, a control device for controlling the fastening force of a fluid coupling according to the present invention controls the slip amount in the fluid coupling to a target value. A first control means for controlling the fastening force of the fluid coupling and detecting that the operating state of the vehicle has changed from an operating state that does not require control by the first control means to an operating state that requires control. and a detection means for detecting the slippage, and upon receiving this detection, stopping the first control means for a predetermined period thereafter and controlling the slip amount so that the engine speed reaches the target value. and second control means for controlling the fastening force of.

[0008]

[Operation] The second control means controls the control by the first control means during the predetermined period after the operating state changes from an operating state that does not require control by the first control means to an operating state that requires control. Since the tightening force control based on the slip amount control is stopped and the slip amount is controlled so that the engine speed reaches the target value, the target value of the engine speed can be suppressed within a range that does not make the driver feel uncomfortable.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Structure of Transmission First, the structure of the torque converter and its control hydraulic circuit will be explained with reference to FIG. In the figure, a torque converter 1 is fixedly installed on one side of a case 3 connected to an engine output shaft 2, and includes a pump 4 that rotates integrally with the engine output shaft 2, and a case that faces the pump 4. A turbine 5 rotatably provided on the other side of the pump 3 and driven to rotate via hydraulic oil by the rotation of the pump 4;
A stator 6 is interposed between the turbine 5 and the turbine 5, and performs a torque increasing action when the speed ratio of the turbine rotation speed to the pump rotation speed is below a predetermined value, and the turbine 5 and the case 3. It has a lockup clutch 7. 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 and the turbine shaft 8 are directly connected via the case 3.

The torque converter 1 is also connected to a lock-up valve 10 and a converter inline 1 through a main line 9 led from an oil pump (not shown).
1, and the pressure of this hydraulic oil constantly urges the lock-up clutch 7 in the tightening direction, and also creates a gap between the clutch 7 and the case 3. A lock-up release line 13 led from the lock-up valve 10 is connected to the space 12, and hydraulic pressure (release pressure) is supplied from the line 13 into the space 12.
When the lock-up clutch 7 is introduced, 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 spring 10b that urges the spool to the right in the drawing, and main lines are connected to both sides of the port 10c to which the lock-up release line 13 is connected. 9 is connected to the pressure regulating port 10d and the drain port 10
e is provided. Furthermore, in the drawing of the valve 10,
A control line 17 for applying pilot pressure to the spool 10a is connected to the right end, and a drain line 18 branched from the control line 17 is provided with a duty solenoid valve 19. . 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 above duty rate. Adjust to the desired value. This pilot pressure is applied to the spool 10a of the lockup valve 10 in a direction opposite to the biasing force of the spring 10b, and the spool 10a is applied to the lockup release line 13 in the same direction as the biasing force of the spring 10b. The release pressure is now applied. The spool 10a is moved by the force relationship of these oil pressures or biasing forces, and the lockup release line 13 is communicated with the main line 9 (pressure adjustment port 10d) or the drain port 10e, so that the lockup release pressure is increased to the above level. The pilot pressure is controlled to a value corresponding to the duty rate of the duty solenoid valve 19.

[0012] When the duty rate is the maximum value, control line 1
When the amount of drain from 7 becomes maximum and the pilot pressure or release pressure becomes minimum, lock-up clutch 7
When the lock-up clutch 7 is fully engaged and the duty rate is at its minimum value, the drain amount is at its minimum, and the pilot pressure or release pressure is at its 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 slip amount of the lock-up clutch 7 is controlled. It is becoming more and more common. Construction of Control Circuit Next, the control circuit for controlling the amount of slip of the lock-up clutch 7 will be explained with reference to FIG. As shown in the figure, this control circuit has a CPU 20.
U20 includes a vehicle speed sensor 21 that detects the vehicle speed V of the vehicle, a throttle sensor 22 that detects the throttle opening θ of the engine, a gear position sensor 23 that detects the gear position G of the automatic transmission, and the engine. An engine rotation sensor 24 that detects the rotation speed NE and the turbine shaft 8
A signal from a turbine rotation sensor 25 that detects the rotation speed NT of the engine is inputted.

The CPU 20 calculates/outputs the duty rate D of the duty solenoid valve 19 based on the signals from the sensors 21 to 25, thereby controlling the torque according to the control procedure shown in the flowchart described later. Controls converter 1 (lock-up clutch 7). Overview of Control In this specification, three methods of controlling the duty rate D of the valve 19 will be disclosed as three embodiments (first to third embodiments). In this specification, the operating range of the vehicle includes a converter operating range III, a lock-up range II where the lock-up clutch engages, and a slip rate control range where slip rate control is performed, depending on the vehicle speed V and the throttle opening θ. There are three I. In the converter region, the duty ratio D is set to DMIN in order to free the lockup clutch 7. In addition, in the lockup region II, the duty ratio D
Let be the maximum value DMAX.

The duty ratio control according to the first to third embodiments is characterized by slip rate control in the slip rate control region. The control results of the first embodiment are shown in FIG. 9, and by referring to FIG. 9, the operation of the first embodiment can be better understood. That is, in the first embodiment, the converter area (D
In the slip rate control area from the area where slip control is turned off (=DMIN) to the lock-up operation area, duty control periods are provided using two methods. In other words, the initial period when the slip control transitions from the OFF state to the ON state (slip amount NS(t
) becomes below the target value NSGL), the duty ratio D is controlled by feedback control (for convenience, this control is
"Engine speed F/B control", on the drawing, "NE
F/B control). After that, when the slip amount NS(t) becomes equal to or less than the target value NSGL, the duty ratio D is controlled so that the slip amount NS(t) converges to the target value NSGL (for convenience, this control is referred to as "slip F
/B control). In the first embodiment, the target value NEGL of the engine speed in the above-mentioned "engine speed F/B control" is the engine speed at the time when the slip control is changed from off to on, and
This target value is not changed during the "B control" period.

On the other hand, in the second embodiment, the target value N of the engine speed during this "engine speed F/B control" period is
I am trying to gradually lower the EGL. That is, the target value NEG of the engine rotation speed, which was a fixed value in the first embodiment,
L changes over time in the second embodiment and is expressed as NEGL(t). The slope (gradient C) at which NEGL(t) decreases over time is determined by taking into account the engine speed at the time the slip control is turned on from off and the reliability of the lock-up clutch, as will be explained later. It is determined by the time T0 determined by In other words, the second embodiment, in addition to the control of the first embodiment,
The control method takes lock-up wear into consideration.

In the third embodiment, as in the first embodiment, duty ratio control is performed during the "engine speed F/B control" period so that the engine speed converges to a fixed target value NEGL. . However, in the first embodiment,
The "engine speed F/B control" period is the slip amount NS (
t) becomes below the target value NSGL, whereas the "engine speed F/B control" period of the third embodiment continues until the slip amount NS(t) becomes below the target value NSGL. Until T0 time elapses, whichever comes first.

[0017] Here, variable names used in the three embodiments will be explained. If the engine speed at a certain point t is NE(t) and the turbine speed is NT(t), the main variables are: D(t): Duty ratio D to be output
(t-1): Duty ratio NS(t) calculated in the previous control cycle = |NE(t)-NT(t)|:
Slip amount FSLIP at t: A flag indicating that slip control is currently being performed, in other words, that the converter is not in the operating range.

FCH: Flag indicating that slip control has changed from off to on NSGL: Target slip amount in slip F/B control NEGL: Target engine speed in engine speed F/B control ΔN(t) = NS (t)-NSGL: Deviation from target slip amount B: Feedback control variables used in "engine speed F/B control" U, ΔD: Feedback control variables used in "slip F/B control". Control of First Embodiment First, control according to the first embodiment will be explained using FIGS. 4 to 9.

[0019] In step S2, the current
Based on the signals from each sensor 21 to 25, the vehicle speed V(t),
Throttle opening θ(t), engine speed NE(t)
, turbine rotational speed NT(t) and gear position G(t). In step S4 (see FIG. 5 for details), the current control area is determined. In step S40 of FIG. 5, the vehicle speed V(
t) and the throttle opening θ(t) are set in advance for each gear stage.
Determine whether it belongs to the converter area. If it belongs to the converter area, no slip control is performed (D
=DMIN), the flags FCH and FSLIP are reset in steps S48 and S50, respectively. If it is determined in step S40 that the slip control does not belong to the converter region, the process proceeds to step S42 and subsequent steps to determine whether or not the slip control is to be transitioned from an OFF state to a state in which the slip control must be performed. , step S42
Check the set state of the flag FSLIP. If this flag is not set, a change in operating status, i.e. F
Since SLIP=0→FSLIP=1, the flag FCH is set in step S44 to memorize this fact.

Returning to the flowchart of FIG. 4, the explanation will be continued. In step S6, it is checked whether or not it was determined in step S4 that the current state is in the slip control region, that is, it is not in the converter operating region. If it is determined that the converter is in the operating range, in step S32,
The current duty ratio D(t) is set to the minimum value DMIN
shall be.

If it is determined in step S6 that the converter is not in the converter operating region, then in step S8, the current state is changed from the converter operating region to the slip control operating region (slip control off→slip control on in FIG. 9). The flag FCH is checked to determine whether there is one. If it is immediately after changing the control mode, step S10
After resetting the flag FCH, the current engine speed NE(t) is stored as the target engine speed NEGL. In the control of this first embodiment, NEGL is set as the target rotation speed in "engine rotation speed F/B control", so
N only once, only when flag FCH is set
Set EGL.

In step S14, the current slip amount N
Calculate S(t) (=|NE(t)−NT(t)| ). In step S16, it is determined whether this slip amount NS(t) is less than or equal to the target slip amount NSGL. This target slip amount NSGL is the slip F/B
This is the target slip amount in control. Therefore, when it is determined in step S16 that NS(t)>NSGL, "
Performing “slip F/B control” reduces the slip amount to N.
In this case, it means to rapidly converge to SGL, that is, to cause a sudden decrease in engine speed.
Proceed to step S18 (~step S28) and select “
Perform engine rotation speed F/B control.

This "engine speed F/B control" is performed by adjusting the duty ratio D (t) so that the engine speed converges to the target value NEGL (set in step S12).
). Specifically, when the current engine speed is NE(t)=NEGL, in step S24, the D(t) that is about to be output is
As, the duty ratio D calculated in the previous control cycle is
(t-1) is used. That is, D(t) = D(t-1
). Immediately after flag FCH is set, NE(
t)=NEGL, the control is at step S18→
The process will proceed to step S24.

[0024] Engine speed NE(t
) will vary. Engine speed is NE(t)>
NEGL, in step S20, the deviation of the engine speed from the target value (=NE(t)−NEGL
) is calculated based on the feedback control amount B, and in step S22, the duty ratio D(t) calculated in the previous control cycle is calculated as D(t) to be output from now on.
The above B is added from t-1). That is, in step S22, the tightening force of the lock-up clutch 7 is increased by setting D(t) = D(t-1) +B, and the engine speed N(t+1) in the next cycle is set to NEGL.
It is lowered towards the Furthermore, when the engine speed is NE(t)<NEGL, step S
In step S26, the feedback control amount B is similarly calculated based on the deviation of the engine speed from the target value (=NE(t)-NEGL), and in step S28, as D(t) to be output from now on, Assume that the above B is subtracted from the duty ratio D(t-1) calculated in the previous control cycle. That is, the tightening force of the lock-up clutch 7 is lowered, and the engine rotation speed N(t
+1) towards NEGL. In this way, "engine speed F/B control" is performed in steps S18 to S28, and the engine speed is equal to the engine speed NEGL when the mode is changed.
is maintained.

[0025] Furthermore, in step S36, D(t+1
)=D(t) is calculated in order to retain D(t) calculated in this control cycle for use in the next control cycle. Continuing the "engine speed F/B control" basically means that the duty ratio D(t) is controlled and as a result, the turbine speed NT(t) gradually increases. do. Therefore, eventually the slip amount NS(
t) will approach the target value NSGL. Then, a YES determination is made in step S16, and the process proceeds to step S16.
30 "slip F/B control" (FIG. 6) is performed.

In the "slip F/B control" shown in FIG. 6, based on the determination in step S52 as to whether or not the current operating conditions are in the lock-up operation range, if the determination is YES, steps S62 and subsequent steps are performed. Lock-up control is performed,
If NO, slip control from step S56 onwards is performed. That is, first, in step S52, the current slip amount NS(t) and the target slip amount NSGL are determined.
Calculate the deviation ΔN(t) from And step S
At step 54, it is determined whether or not the above-mentioned lock-up control should be performed. If this determination is YES, the duty ratio D(t) is set to the maximum value Dmax in step S62. This causes the transmission to be locked up.

When the determination in step S54 is NO, the feedback control amount U(t) is changed to the current deviation ΔN.
(t) and the previous deviation ΔN(t+1). U(t) =k·ΔN(t) +l·ΔN(t+1) where k and l are control parameters (constants or variables). In step S58, the duty rate D(t) corresponding to this feedback amount U is determined based on this U(t).
The current duty rate D(t) is set by setting the correction amount ΔD(t) based on the map in FIG. ) is calculated.

In step S64, the current deviation ΔN(t)
is stored as ΔN(t+1) for the next control. With such "slip F/B control", when the current and previous deviations ΔN(t) and ΔN(t+1) are negative, that is, the actual slip amount NS(t) becomes the target slip amount NS.
When it is smaller than GL, the feedback amount U(t) and the correction amount ΔD(t) of the duty rate D(t) also become negative, and accordingly, the duty rate D(t) decreases and the duty solenoid valve 19 As the amount of drain from the pump decreases, the pilot pressure or lock-up release pressure increases, and as a result, the lock-up clutch is controlled in the release direction and the actual slip amount increases, approaching the target slip amount NSGL. . Also, on the contrary,
When the current and previous deviations ΔN(t) and ΔN(t+1) are positive, that is, when the actual slip amount NS(t) is larger than the target slip amount NSGL, the duty rate D(t) is increased and the pilot pressure is increased. Otherwise, the lock-up clutch 7 is controlled in the engagement direction, and the actual slip amount NS(t) decreases and approaches the target slip amount NSGL. Furthermore, the current deviation ΔN(t) and the previous deviation ΔN
If the sign of (t-1) is opposite, that is, the actual slip amount NS
(t) has substantially converged to the target slip amount NSGL, the feedback amount U(t) or the correction amount ΔD(t) of the duty rate becomes zero or an extremely small value, and therefore the actual slip amount NS(t) ) is the target slip amount NSGL
, or will be kept at a very small value.

In this way, in the slip region I, the actual slip amount NS(t) is equal to the target slip amount NSGL.
However, the above feedback amount U
When calculating (t), the current deviation ΔN(t) and the previous deviation ΔN(t-1) are used, so good control stability and convergence can be obtained. Since the deviation ΔN(t) obtained in the control cycle is replaced with the previous value ΔN(t-1), the subtraction process when calculating the amount of feedback only requires the process of calculating the deviation ΔN for each control cycle. Therefore, the calculation of the feedback amount U(t) is facilitated. Control of Second Embodiment In this second embodiment, the target value NEGL of the engine speed during the "engine speed F/B control" period is gradually lowered over time. In the first embodiment described above, the target value NEGL of the engine speed was fixed. On the other hand, in this second embodiment, the target value NEGL(t
) changes over time. The flowchart of the control procedure of the second embodiment is as follows for "slip control determination" and "slip F/B control" in FIGS. 5 and 6 of the first embodiment.
to be used.

In FIG. 10, steps S80 to S88 and step S106 are the same as steps S2 to S10 and step S32 in the first embodiment. When a transition from the converter operating region to the slip control region is detected as described in the first embodiment, in step S90, the current engine speed N
E(t) is saved as the target value NEGL(t). Next, in step S92, the reduction rate C of NEGL(t) is calculated according to the following formula.

C={NE(t)-NT(t)}/2T0
This reduction rate C can be better understood with reference to FIG. In FIG. 12, the broken line shows the engine speed, the solid line shows the turbine speed, and the dashed line shows the straight line having the above-mentioned C tilt. Further, T0 is a time width in which the reliability of the clutch is ensured, and is a known value.

[0032] The engine rotation speed and turbine rotation speed at the time when the flag FCH is set are NEGL (0).
, NT(0), this rotational speed difference (=
NEGL(0)-NT(0)) must converge within the target deviation during time T0 to ensure clutch reliability. In "engine speed F/B control", the engine speed is converged to a target value, and as a result, the turbine speed also increases, so as shown in FIG. 12,
The line of decrease in engine speed is C(={NE(t)−
NT(t)}/2T0). If the decreasing line of the engine rotational speed is set to such a slope, the turbine rotational speed will also be on the increasing line with approximately the same slope, so after time T0, the deviation between the engine rotational speed and the turbine rotational speed, that is, the slip amount approximately approaches "0".

Steps S94 and S96 are substantially the same as the corresponding parts in the first embodiment. FIG. 11 shows the details of the "engine speed F/B control" (second embodiment) that is executed when it is determined in step S96 that it is necessary to perform the "engine speed F/B control". be. Figure 1
Steps S110 to S120 of the control procedure in step 1 are different from steps S18 to S28 in FIG. t). This subtraction of NEGL(t) over time is performed in step S120 as NEGL(t+1)=NEGL(t)+C.

[0034] In the above formula, it is assumed that the engine rotation speed decreasing line and the turbine rotation speed increasing line have the same tendency, but if they do not have the same tendency, the above formula can be changed. So, C={NEGL(t)-NT(t)}/(α・T0)
You can also use it as Here, α is a function of the gear G and engine rotation speed N set for each transmission. Control of Third Embodiment In this third embodiment, as in the first embodiment, during the "engine speed F/B control" period, the duty is set so that the engine speed converges to a fixed target value NEGL. Perform ratio control. However, in the first embodiment, the "engine speed F/B control" period continues until the slip amount NS(t) becomes equal to or less than the target value NSGL, whereas the third embodiment
The "engine speed F/B control" period of the embodiment is performed until the slip amount NS(t) becomes equal to or less than the target value NSGL.
Until the T0 time elapses, whichever comes first.

The flowchart of the control procedure of the third embodiment uses FIG. 6 of the first embodiment for the flowchart of "slip F/B control". Further, regarding the main control procedure, FIG. 4 of the first embodiment is used, and a part thereof is further modified as shown in FIG. 14. Furthermore, in the third embodiment, “
"Slip control judgment" is changed as shown in FIG.

The control procedure of the third embodiment will be briefly explained. In the third embodiment, a timer T0 is used to monitor the passage of time T0 after changing the slip control mode.
Use M. That is, when such a mode change is detected, the flag FCH is set (step S134).
), the timer TM is activated in step S136. Thereafter, unless the flag FSLIP is set and the timer TM does not time out, the timer TM is decremented in step S142.

[0037] The case when the timer TM times out will be explained. As mentioned above, FIG. 4 of the first embodiment is used for the control procedure of the third embodiment. That is, FIG.
When it is determined in step S16 that "engine speed F/B control" is necessary, the process proceeds from step S16 to step S150 according to the control procedure shown in FIG. 14, and it is determined whether or not a timeout has occurred. If TM=0, the process advances to step S30 ("slip F/B control") in FIG. 4, and TM≠
If it is 0, the process advances to step S18 ("engine speed F/B control"). In other words, as long as TM has timed out, that is, after time T0 has elapsed after the mode change, even if it is determined that engine speed F/B control is necessary, in order to ensure clutch reliability, Forcibly perform slip F/B control.

The control of the third embodiment is simpler than that of the second embodiment. The time required for "engine speed F/B control" to avoid sudden changes in engine speed varies depending on the engine speed, road gradient, and gear ratio at that time, but does not vary greatly. Therefore,
This third embodiment simultaneously prevents sudden changes in engine speed, prevents clutch wear, and simplifies the control procedure.

[0039]

As explained above, the control device for controlling the fastening force of a fluid coupling according to the present invention controls the fastening force of the fluid coupling by controlling the amount of slip in the fluid coupling to a target value. a first control means for controlling;
a detection means for detecting that the driving state of the vehicle has changed from a driving state that does not require control by the first control means to a driving state that requires control; and upon receiving this detection, a subsequent predetermined period; Stopping the first control means, and
The present invention is characterized by comprising second control means for controlling the fastening force of the fluid coupling by controlling the slip amount so that the engine speed becomes a target value.

[0040] That is, the second control means controls the first control during the predetermined period after the operating state changes from an operating state that does not require control by the first control means to an operating state that requires control. Since the fastening force control by the slip amount control by means is stopped and the slip amount is controlled so that the engine speed reaches the target value, if the target value of the engine speed is kept within a range where the driver does not feel any discomfort. good.

According to a preferred embodiment of the present invention, the target value of the engine rotation speed in the second control means is maintained at the engine rotation speed at the time of detection by the detection means for the predetermined period. That is, until the slip amount control by the first control means starts, the engine speed is maintained at the engine speed at the time of detection, so there is almost no change in the engine speed.

According to a preferred embodiment of the present invention, the target value of the engine rotation speed in the second control means is set to the engine rotation speed at that time when the detection means detects the target value, and the target value of the engine rotation speed in the second control means is set to the engine rotation speed at that time, and It is gradually reduced during the period. By doing this, the amount of slip converges to the target value more quickly, and wear due to slip inside the fluid coupling is reduced.

According to a preferred embodiment of the present invention, the predetermined period is a period until the slip rate reaches the target value. In other words, until the slip amount reaches the target value, that is, until the engine speed changes little even after control by the first control means is started, the feedback based on the engine speed is maintained. Since the control is performed, even if the control by the second control means ends and the control by the first control means starts, fluctuations in the engine speed at that point are suppressed as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating conventional problems.

FIG. 2 is a sectional view of a vehicle torque converter according to an embodiment of the present invention and a fluid control circuit diagram therefor.

FIG. 3 is a control circuit diagram for controlling the lock-up valve of the torque converter of FIG. 2;

[Figure 4] ~

FIG. 6 is a flowchart showing a control procedure according to the first embodiment of the present invention.

FIG. 7 is a map diagram for determining a control region in control according to the first to third embodiments of the present invention.

FIG. 8 is a graph diagram used when calculating a control variable ΔD when performing slip feedback control in the control according to the first to third embodiments of the present invention.

FIG. 9 is a timing chart specifically showing the control operation of the first embodiment.

[Figure 10] ~

FIG. 11 is a flowchart showing a control procedure according to a second embodiment of the present invention.

FIG. 12 is a timing chart specifically showing the control operation of the second embodiment.

[Figure 13] ~

FIG. 14 is a flowchart specifically showing the control operation of the third embodiment.

[Explanation of symbols]

10 Lock-up valve 19 Solenoid valve 20 CPU 21 Vehicle speed sensor 22 Throttle sensor 23 Gear shift sensor 24 Engine speed sensor 25 Turbine rotation speed sensor

Claims (5)

[Claims] 1. A control device for controlling the fastening force of a fluid coupling, wherein a first control for controlling the fastening force of the fluid coupling by controlling the amount of slip in the fluid coupling to a target value. a detecting means for detecting that the driving state of the vehicle has changed from a driving state that does not require control by the first control means to a driving state that requires control; By stopping the first control means and controlling the slip amount so that the engine speed reaches the target value during the period of
A fastening force control device for a fluid coupling, comprising: second control means for controlling the fastening force of the fluid coupling. 2. The target value of the engine rotation speed in the second control means is maintained at the engine rotation speed at the time of detection by the detection means for the predetermined period of time. A fastening force control device for a fluid coupling according to item 1. 3. The target value of the engine rotation speed in the second control means is set to the engine rotation speed at that time when detected by the detection means, and is gradually decreased during the subsequent predetermined period. A fastening force control device for a fluid coupling according to claim 1. 4. The fastening force of the fluid coupling according to claim 1, wherein the predetermined period is a period until the slip ratio reaches a target value. Control device. 5. The fastening force control device for a fluid coupling according to claim 1, wherein the predetermined period is a period from the time of detection by the detection means until a predetermined time elapses. .