JP2000304127A - Control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the various inconveniences caused by the engagement delay of a forward clutch in releasing neutral control. SOLUTION: The target change rate of a turbine rotation speed Nt for returning a forward clutch to an engage state is increased and corrected (K1, K2, K3) by this control device when the acceleration operation is carried out at the release time of a neutral control. Thereby, the forward clutch is returned to the engage state, before an engine is blowed up by the rising of an engine torque and the smooth departure is realized.

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 an automatic transmission, and more particularly to a control device for reducing a creep phenomenon caused by a torque converter during a stop in a traveling range.

[0002]

2. Description of the Related Art As is well known, a D range (running range) is used.
When the automatic transmission is stopped, the transmission mechanism is held at a low speed stage in preparation for the next start, and the torque of the engine is transmitted to the drive wheels via a torque converter, so that the vehicle slightly advances. Creep phenomenon has occurred. If the shift position is switched to the N range (non-running range), the transmission mechanism will be in a neutral state, and the creep phenomenon will not occur. The operation to suppress the creep phenomenon by the foot brake is performed with the range.

However, since the load torque is applied to the engine at this time as a reaction of the creep phenomenon, the fuel consumption tends to increase in order to maintain the idling speed against the load torque, and the torque is increased. There is a problem that uncomfortable idle vibration is generated due to antagonism between the engine torque and the braking force transmitted to the drive wheel side via the converter.

Therefore, when the vehicle is stopped in the D range, the friction engagement element (hereinafter, referred to as a forward clutch) that has been engaged to achieve the low speed (for example, the first speed) does not cause the creep phenomenon. A control device has been proposed in which a so-called neutral control for controlling the slip amount to a certain extent is performed, thereby reducing the engine torque transmitted through the torque converter to reduce the fuel consumption and idle vibration. I have.

[0005] The conditions for canceling the neutral control include the suspension of the operation of the foot brake, the operation of the accelerator, and the vehicle speed exceeding a predetermined value. When any of the conditions is satisfied, the turbine speed is changed at a predetermined rate of change. The duty ratio of the solenoid for the forward clutch is feedback-controlled so as to decrease, the forward clutch is operated toward the engagement side, the duty ratio is finally increased to 100%, and the clutch is fully engaged. Prepare. The rate of change of the turbine speed applied at this time is based on the engine speed at the time when the release condition is satisfied, so as to prevent sudden engagement of the clutch and to complete the engagement of the clutch before starting. You have set.

[0006]

However, the above-mentioned setting of the target change rate of the turbine speed is based on a very general operating condition, and in the following case, the target change rate is too small. As a result, the clutch engagement may be delayed and a malfunction may occur. First, if the accelerator is suddenly operated during the neutral control release process, or if the neutral control is released based on the accelerator operation while the brake operation is continued, the engine torque will suddenly increase shortly before the forward clutch is fully engaged. Will be launched. As a result, as shown by the dashed line in FIG. 6, a situation occurs in which the torque is not transmitted to the drive wheel side only because the engine blows up, and then the clutch is completely engaged with a shock. There was a problem that can not be expected.

In addition, when the vehicle starts on an uphill road, the vehicle may retreat against the driver's intention until the neutral control is released by stopping the brake operation and the creep phenomenon occurs. An object of the present invention is to provide a control device for an automatic transmission that can prevent various problems such as an engagement shock due to a delay in engagement of a forward clutch and a backward movement of a vehicle when canceling neutral control. It is in.

[0008]

In order to achieve the above object, according to the present invention, when a control start condition is satisfied, a specific frictional engagement element is controlled to a predetermined slip state by a slip state control means. When a predetermined control release condition is satisfied based on the driver's starting intention, the control release means reduces the input rotation speed of the friction engagement element according to a predetermined rate of change to return to the engaged state. During the return to the combined state, when at least one of the increase of the engine torque and the retreat of the vehicle is determined, the change rate correction means corrects the change rate of the input rotational speed to increase correction.

Therefore, for example, when the engine torque suddenly rises due to sudden operation of the accelerator or the like, the input rotation speed is rapidly reduced in accordance with the rate of change corrected by the increase, so that the friction engagement element is increased before the engine blows up. Is returned to the engaged state, smooth start is realized.Also, when the vehicle starts retreating due to suspension of the brake operation when starting on an uphill road, the rapid engagement of the friction engagement element The backward movement of the vehicle against the driver's will is prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for an automatic transmission according to the present invention will be described below. As shown in FIG. 1, the automatic transmission 1 is mounted on a vehicle (not shown) in a state where the automatic transmission 1 is connected to an engine 2. Output shaft 2a of engine 2
Is connected to a speed change mechanism 4 via a torque converter 3,
The transmission mechanism 4 is connected to driving wheels of the vehicle via a differential gear 5. Output shaft 2a of engine 2
At the same time, when the pump impeller 3a of the torque converter 3 rotates, the turbine runner 3b is rotationally driven via an ATF (Automatic Transmission Fluid), and the rotation is transmitted to the speed change mechanism 4. Although not described in detail, the transmission mechanism 4 includes a plurality of sets of planetary gear mechanisms and clutches and brakes that allow or restrict the operation of the constituent elements (sun gear, pinion gear, and ring gear). The desired gear is obtained by appropriately switching the engagement state of the brake and the brake by the ATF supplied from the hydraulic pressure source 6.

Here, when the automatic transmission 1 is switched from the N range (non-traveling range) to the D range (traveling range), the transmission mechanism 4 is switched to the first speed in preparation for starting. Is the forward clutch 7 in the speed change mechanism 4
(The clutch engaged at the time of forward movement) and the first-speed brake 8 are engaged together. As described later, the neutral control is performed by controlling the slip amount of the forward clutch 7 as the friction engagement element.

An input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.) for storing control programs and control maps, and a central processing unit (C)
An automatic transmission control unit (A / T-CU) 11 having a PU, a timer counter and the like is installed, and performs comprehensive control of the automatic transmission 1. On the input side of the A / T-CU 11, an engine speed sensor 12 for detecting the speed Ne of the engine 2 and the speed Nt of the turbine runner 3b are provided.
, A vehicle speed sensor 14 for detecting the running speed Vs of the vehicle, a stop lamp switch 15 for detecting the operation of the foot brake, and the engine 2.
The throttle sensor 16 detects the throttle opening θTH (= accelerator operation amount), the oil temperature sensor 17 detects the ATF oil temperature TOIL, and the shift position selected by the driver (for example, N range, D range, P range). Range, R range, etc.). On the output side of the A / T-CU 11,
A large number of solenoids 19 are connected to switch the hydraulic oil from the hydraulic pressure source 6 to operate the clutches and brakes of the transmission mechanism 4. The A / T-CU 11 switches the engagement state of the clutch and the brake of the transmission mechanism 4 according to a shift point map (not shown) based on the throttle opening θTH and the vehicle speed Vs, and executes shift control.

Next, the execution state of the neutral control by the control device for the automatic transmission configured as described above will be described with reference to FIGS. The flowcharts of FIGS. 2 to 4 are for neutral control of the forward clutch 7 when the vehicle traveling in the D range is stopped, and the time chart of FIG. 5 shows the overall control state of the neutral control. It is a thing.

The A / T-CU 11 executes a neutral control routine shown in FIGS. 2 and 3 at predetermined time intervals. First, the A / T-CU 11 determines in step S2 whether or not a neutral control start condition has been satisfied. In the present embodiment, the following start conditions are set, and when all of them are satisfied, that is, when it is estimated that the vehicle has transitioned from the running state to the almost stopped state, it is considered that the start condition is satisfied.

1) The brake operation is detected by the stop lamp switch 15. 2) The throttle sensor 16 detects that the accelerator is not operated (throttle opening is less than a predetermined amount). 3) The traveling speed Vs detected by the vehicle speed sensor 14 is less than a predetermined value. If the start condition is not satisfied in step S2, NO
A negative determination is made and the routine ends. When the neutral control start condition is satisfied, YES
After making a positive determination, the process proceeds to step S4, and a slip determination is made. In the neutral control, the forward clutch 7 is maintained at a predetermined slip amount. Therefore, at the start of the control, the clutch 7 that has been engaged for traveling needs to be operated to the disengagement side to near the predetermined slip amount. Hereinafter, this processing is referred to as a preliminary operation. The slip determination is for determining the completion of the preliminary operation, and the turbine rotation speed Nt increases from 0 and the slip determination value Nt0.
(E.g., 50 rpm), it is estimated that the forward clutch 7 has been operated to near the predetermined slip amount,
The slip is determined as the completion of the preliminary operation.

If the turbine rotational speed Nt is still equal to or smaller than the slip determination value Nt0 and the determination in step S4 is NO, the duty ratio D of the forward clutch solenoid 19 is calculated and output as a preliminary operation in step S8. Thereafter, in step S10, it is determined whether or not a neutral control release condition described later is satisfied. If the release condition is not satisfied, the process returns to step S4. The calculation process of the duty ratio D in step S8 is performed according to the following equation (1).

D = DN-DNS (1) where DN is a slip immediately before slip value set as a duty ratio immediately before the forward clutch 7 in the engaged state starts to slip, and DNS is 0 as a starting point. This is a gradient term that is set to increase at a predetermined rate every time step S8 is executed. Therefore, as shown in FIG. 5, immediately after the neutral control start condition is satisfied, the duty ratio D of the solenoid 19 becomes 100%.
% To a value just before the slip DN (step a in FIG. 5), and thereafter gradually decreases according to the gradient term DNS. The forward clutch 7 is gradually operated to the release side,
The turbine rotation speed Nt stopped and held in the engaged state
When the turbine rotation speed Nt exceeds the slip determination value Nt0 (because the turbine runner 3b is connected to the driving wheel side via the forward clutch 7), A /
The T-ECU 11 makes a determination of YES in step S4,
At step S18, slip control is executed.

The slip control is performed by feedback-controlling the duty ratio D of the solenoid 19 so that the slip amount ΔN (= Ne−Nt) of the torque converter 3 becomes a preset target value. As the initial value of the duty ratio D, a value obtained by adding a predetermined value ΔDSB (for example, 2% of the duty ratio D) to the last duty ratio D gradually reduced in the preliminary operation in step S8 is applied (point in FIG. 5). b). The process of step S18 is repeated until the neutral control release condition is satisfied in step S10.
As shown in FIG. 5, the slip amount ΔN is held near the target value. In the present embodiment, the A / T-CU 11 when executing the processing of steps S2, S4, S8, and S18 functions as a slip state control unit.

On the other hand, the neutral control release condition is set as follows. When any of the conditions is satisfied, that is, when the driver's intention to start is estimated, it is considered that the release condition is satisfied. 1) Stop operation of the brake is detected by the stop lamp switch 15. 2) The accelerator operation (throttle opening is equal to or more than a predetermined value) is detected by the throttle sensor 16.

3) The traveling speed Vs detected by the vehicle speed sensor 14 is equal to or higher than a predetermined value. If any of the release conditions is satisfied and the determination in step S10 becomes YES (point c in FIG. 5), the A / T-CU
11 is a step S22 for determining whether or not the establishment of the release condition is caused by the above 2), in other words, whether or not the accelerator operation is started under the situation of continuing the brake operation and the release condition is satisfied. judge. In a normal driving operation, since the accelerator operation is started by depressing the pedal after the brake operation is stopped, the release condition is satisfied due to 1), and a negative determination is made in step S22, and a negative determination is made in step S24.
Sets the last duty ratio D used for neutral control as an initial value. Further, when the release condition is satisfied due to 2) and a determination of YES is made in step S22, the last duty ratio D is set to a predetermined value Δ in step S26.
A value obtained by adding DES is set as an initial value.

Thereafter, in step S28, a target change rate ΔNT1 is set as described later. In step S30, a process of calculating a throttle correction amount DTH based on the throttle opening θTH is performed. In step S32, an engine speed correction based on the engine speed Ne is performed. A calculation process of the quantity DNE is executed. Further, in step S34, step S24 or step S2 is performed.
Using the initial value set in step 6, feedback control is performed on the duty ratio D so that the turbine rotation speed Nt decreases in accordance with the target change rate ΔNT1 set in step S28.

Although not described in detail, the throttle correction amount DTH is a correction amount for suppressing slippage by increasing the hydraulic pressure of the forward clutch 7 in accordance with the accelerator depression amount (increase in engine torque). The engine rotation correction amount DNE is a correction amount for eliminating the influence of the fluctuation of the ATF line pressure generated near the idle rotation.
The correction amounts DTH and DNE are applied to the duty ratio D by being applied at the time of the feedback control in step S34.
Each function is performed.

With the above processing, the turbine rotation speed Nt gradually decreases, and the forward clutch 7 is operated to the engagement side. Here, the reason why the initial value of the duty ratio D is increased and corrected in step S26 is that in this case, it is expected that the engine torque will rise immediately after the release condition is satisfied, causing the forward clutch 7 to slip. Therefore, this situation is prevented by the instantaneous startup of hydraulic pressure.

In the following step S36, the A / T-CU 11 determines whether or not the turbine rotational speed Nt is less than 300 rpm.
Until a determination of YES is made, the processing of steps S28 to S34 is repeated. Turbine rotation speed Nt is 30
If the speed falls below 0 rpm and the determination in step S36 becomes YES (point d in FIG. 5), the target change rate ΔNT2 (| ΔNT2 | <| ΔNT1 |) as described later in step S38, as in steps S28 to S32 described above. ) Is set, and the process of calculating the throttle correction amount DTH is executed in step S40, and the process of calculating the engine rotation correction amount DNE is executed in step S42. Further, in step S44, the last duty ratio D (the duty ratio D at the point d in FIG. 5) used in the processing in step S34 is set as an initial value, and the duty ratio is set so that the turbine rotation speed Nt decreases in accordance with the target change rate ΔNT2. The rate D is feedback-controlled, and a synchronization determination is made in step S46. This synchronization determination is a process for determining whether or not the forward clutch 7 has been operated to near the engagement by the feedback control in step S44. Specifically, when the turbine rotation speed Nt is 100r
It is determined whether it is less than pm.

With the above processing, the speed of decrease of the turbine rotational speed Nt becomes slower, and if the synchronization is determined in step S46, the last duty ratio D used in the processing of step S44 is reduced in step S48. Predetermined value Δ
A value DE obtained by adding DFF is output (point e in FIG. 5),
In step S50, it is determined whether or not a predetermined time TE set in advance has elapsed. That is, after the synchronization is determined, the forward clutch 7 is considered to be engageable by open loop control, and the predetermined value DE is applied.

Then, by repeating step S48, the forward clutch 7 is engaged, and the turbine rotational speed N
t decreases to a value corresponding to the vehicle speed Vs at this time. When the predetermined time TE has elapsed and the determination in step S50 is YES, the duty ratio is held at 100% in step S52 (point f in FIG. 5), and this routine ends. In this embodiment, steps S22 to S22 are performed.
The A / T-CU 11 when executing the processing of 52 functions as control release means.

Therefore, the forward clutch 7 is completely engaged with the rise of the hydraulic pressure, and the shift to the first shift stage is completed, and the engine speed Ne is controlled by the accelerator operation of the driver.
Rises, the rotation of the output shaft 2a of the engine 2 is transmitted to the transmission mechanism 4 via the torque converter 3, and the vehicle starts. Since the time required from the neutral control release condition being satisfied (indicating the driver's intention to start) to actually completing the shift to the first speed is very short, the driver may feel uncomfortable when starting. I will not hold you.

On the other hand, step S28 and step S28
The setting process of the target change rates ΔNT1 and ΔNT2 of FIG.
Is performed according to the ΔNT setting routine shown in FIG. A / T-
First, in step S62, the CU 11 calculates the base value ΔNT0 according to the following equation (2). ΔNT0 = − (a + b · Ne) (2) where a and b are coefficients, and target change rates ΔNT1, ΔNT1
It is set individually according to NT2. When calculating the target change rate ΔNT1, the engine speed Ne at the time when the neutral control release condition is satisfied (point c in FIG. 5) is applied, and when calculating the target change rate ΔNT2, the turbine rotation speed Ne is used. The engine speed Ne at the time when Nt falls below 300 rpm (point d in FIG. 5) is applied. The base value ΔNT0 of the target change rates ΔNT1 and ΔNT2 is set based on the engine rotation speed Ne for the following reason.

The engine rotation speed Ne during the normal neutral control is 600 to 700 rpm. However, at a low temperature, the engine rotation speed Ne may rise to about 1000 rpm due to idle-up. For example, the normal engine rotation speed Ne (600 to
700 rpm), the target change rates ΔNT1, ΔNT2
Is set, the normal start operation (the accelerator operation is started after the brake operation is stopped) causes the engine torque to rise after the clutch is engaged, so that no shock is generated.

However, the same target change rate ΔNT1, ΔNT1
When NT2 is applied at low temperature (1000 rpm),
Even during a normal start operation, the time from neutral control release to clutch engagement is prolonged, so that the engine torque rises by the accelerator operation before the clutch is engaged, and a shock is generated by the subsequent sudden engagement. . Therefore, in step S62, when the engine rotation speed Ne is high, the base value ΔN
T0 is set to a large value so that the clutch can be engaged in the same required time in any case.

Needless to say, a larger base value ΔNT0 is set when the target change rate ΔNT1 is calculated so that the correlation between the target change rates is ΔNT2 <ΔNT1 as described above. Next, in step S64, it is determined whether or not any of the conditions of the execution of the accelerator operation (for example, the throttle opening voltage is 0.8 V or more) or the vehicle speed Vs ≠ 0 (for example, 1 km / h or more) is satisfied. I do. When the determination is NO, K0 is set as the correction coefficient K in step S66.
Is set, and in step S68, the rate of change Δ
After calculating NT, this routine ends.

.DELTA.NT = .DELTA.NT0.times.K (3) Further, when the determination of YES is made in step S64,
In step S70, it is determined whether or not the accelerator operation is being performed. If NO, the correction coefficient K is determined in step S72.
Is set as K1, and the routine goes to the step S68. Further, when the determination in step S70 is YES,
It is determined in step S74 whether or not the vehicle speed Vs ≠ 0. If NO, K2 is set as the correction coefficient K in step S76, and if YES, K3 is set as the correction coefficient K in step S78. In the present embodiment, the above step S62
A / T-C when executing the processing of step S78
U11 functions as a change rate correction unit.

In this embodiment, the correction coefficient K
0 is set to 1.0 in advance, and the other correction coefficients K1, K2, and K3 are set to 1.5 in advance. Therefore, when the accelerator operation is performed or at least one of the vehicle speeds Vs ≠ 0 occurs, a larger correction coefficient K (K1, K2, K3) than the normal time (K0) indicated by a solid line in FIG. Is set and the target change rates ΔNT1 and ΔNT2 are corrected to increase, so that the turbine rotation speed Nt rapidly decreases as shown by the broken line, and the synchronization determination in step S46 is made early, and the forward clutch 7 is completely engaged. Is done.

Therefore, even if the accelerator is suddenly operated during the neutral control canceling process, or if the neutral torque is canceled based on the accelerator operation and the engine torque suddenly rises, the engine is still blown. Since the forward clutch 7 is completely engaged before being raised, engagement shock can be prevented and smooth start can be realized. In addition, when the vehicle is started on an uphill road, when the neutral control is released by stopping the brake operation, the condition of the vehicle speed Vs ≠ 0 is immediately satisfied by a slight retreat of the vehicle, so that the forward clutch 7 is immediately fully engaged. As a result, the vehicle can be prevented from moving backward against the driver's will.

Further, as described in detail above, a very simple process of increasing and correcting the target change rates .DELTA.NT1 and .DELTA.NT2, which are the target values of the feedback control, by the correction coefficients K0 to K3, requires a slight program change. It is possible to obtain the effect of the present invention. By the way, as is well known, the vehicle speed sensor 14 is based on the principle of operation that counts pulses output with the rotation of the drive wheels and converts the pulses into the vehicle speed Vs.
Even if the moving direction of the vehicle cannot be determined, and the vehicle moves forward on a downhill, the forward clutch 7 is engaged early. However, in this case, since the output rotation of the forward clutch 7 has increased to some extent together with the vehicle speed Vs, it does not cause a shock at the time of engagement. still,
Instead of using the existing vehicle speed sensor 14, a sensor that can determine only the backward movement of the vehicle may be provided, and the output of the sensor may be used.

The description of the embodiment has been completed above, but the embodiments of the present invention are not limited to this embodiment. For example,
In the above embodiment, the case where the neutral control is started along with the stop of the vehicle has been described. However, the start situation of the neutral control is not limited to this. For example, based on switching from the N range to the D range while the vehicle is stopped, Even if the neutral control is started immediately without shifting to the first speed, the same release processing as in the above-described embodiment is executed.
Similar functions and effects can be obtained.

In the above embodiment, the target change rate ΔNT
1, the correction coefficient K0 for .DELTA.NT2 is set to 1.0, and the other correction coefficients K1, K2, and K3 are set to 1.5. Preferably, the relation of K0 <K1 <K2 <K3, at least K0 <K1, K
A value other than the above may be set as long as the relationship of 2, K3 is satisfied. Further, in the above-described embodiment, the control device of the stepped automatic transmission is embodied. However, the control device of the stepless automatic transmission may be embodied. In this case, the friction engagement element that switches the forward / reverse speed may be controlled.

[0038]

As described above, according to the control apparatus for an automatic transmission of the present invention, when the control of the slipping state of the friction engagement element is canceled, the input of the engine torque or the retreat of the vehicle is determined. Since the change rate of the rotation speed is corrected to be increased and the friction engagement element is quickly returned to the engagement state, various problems caused by the delay in engagement can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a control device for an automatic transmission according to an embodiment.

FIG. 2 is a flowchart showing a neutral control routine executed by the A / T-CU.

FIG. 3 is a flowchart showing a neutral control routine executed by the A / T-CU.

FIG. 4 is a flowchart illustrating a ΔNT setting routine executed by the A / T-CU.

FIG. 5 is a time chart showing the overall execution status of the neutral control.

FIG. 6 is a time chart showing a control situation when an accelerator operation is performed during the release processing.

[Explanation of symbols]

7 forward clutch (friction engagement element) 11 A / T-CU (slip state control means, control release means, change rate correction means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16H 59:44 59:54 (72) Inventor Katsutoshi Usuki 5-33-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors F term in Industrial Co., Ltd. (reference) 3D041 AA43 AA59 AA68 AA75 AB01 AC08 AC15 AC18 AD03 AD04 AD10 AD23 AD31 AD33 AD41 AD51 AE14 AE20 AE39 AF01 AF09 3J052 AA04 AA14 CA02 CA03 CA05 CB07 CB16 EA03 FB35 GC04 GC01 LA01 3J057 AA04 BB03 GA43 GA66 GB02 GB04 GB05 GB22 GB23 GB27 GB36 GE08 GE13 HH01 JJ04

Claims (1)

[Claims] 1. A slip state control means for controlling a specific frictional engagement element for achieving a predetermined gear position to a predetermined slip state when a preset control start condition is satisfied; Control release means for reducing the input rotation speed of the friction engagement element according to a predetermined rate of change and returning to an engaged state when a predetermined control release condition is established based on the control release means; During the return of
A control device for an automatic transmission, comprising: a change rate correction unit configured to increase and correct the change rate of the input rotation speed when at least one of an increase in the engine torque and a retreat of the vehicle is determined. .