JP2001004015A - Transmission control device for automatic transmission - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a shift control device for an automatic transmission, in idle neutral control, it is possible to bring the automatic transmission as close as possible to a neutral state irrespective of individual differences and operating conditions of the automatic transmission. I do. When an automatic transmission is determined to be at a neutral position, a learning unit learns a speed ratio of an input shaft rotation speed to an engine rotation speed. Then, based on the learned value of the speed ratio at the neutral position, the target speed ratio is set by the target speed ratio setting means 5, and when the traveling position is reached and the vehicle is stopped, the speed ratio is set to the set target speed ratio. A frictional engagement element 2 for connecting and disconnecting the transmission of the driving force input from the engine to the input shaft 21 to the driving wheels.
2 is controlled by the control means 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission suitable for use in an automobile.

[0002]

2. Description of the Related Art Automatic transmissions provided in automobiles and the like are:
A plurality of frictional engagement elements such as a hydraulic clutch and a hydraulic brake are provided inside, and various controls such as achievement of a predetermined gear stage can be performed by appropriately releasing and connecting the frictional engagement elements. In recent years, idle neutral control has been put to practical use in an automatic transmission of a type in which an input shaft is connected to an engine via a torque converter (fluid coupling).

[0003] The idle neutral control means that even when the shift position of the automatic transmission is in the D range (running position), when the vehicle is stopped (mainly when the brake is operated) (ie, When the gear is in the N range (neutral position) or the P range (parking position), the control is performed so as to approach a neutral state when the shift speed is in the N range (neutral position) or the P range (parking position). The purpose is to improve fuel economy and reduce vibration. .

Hereinafter, idle neutral control will be specifically described with reference to a skeleton diagram in FIG. The structure of the automatic transmission shown in the skeleton diagram is the same as that of the conventional one, and is not a feature of the present invention. Normally, when the shift position is in the D range and the vehicle is stopped, the first speed is selected as the shift speed, and therefore, among the friction engagement elements 22 to 26, the UD (under drive) clutch 22, Although the LR (low reverse) brake 23 is engaged, the vehicle is stopped, that is, the tires are stopped. As a result, the rotation of the turbine shaft 21 is restrained, and the turbine 27 is stopped.
On the other hand, since the pump impeller 28 rotates together with the engine, slippage occurs between the turbine 27 and the pump impeller 28 in the torque converter 20. The greater the slip between the pump impeller 28 and the turbine 27, the greater the load on the engine, resulting in poor fuel economy and increased vibration.

At this time, if the coupling of the UD clutch 22 is weakened while the coupling state of the LR brake 23 remains unchanged, the UD clutch 22 slips due to the torque transmitted from the pump impeller 28 to the turbine 27, and the turbine shaft 21 The rotation is allowed, the slip between the pump impeller 28 and the turbine 27 is reduced, and the load on the engine is reduced. Then, as the ratio of the turbine rotational speed N _T with respect to the engine rotational speed N _E (speed ratio) N _T / N _E approaches 1,
The load on the engine is reduced.

Therefore, in the idle neutral control, a target speed ratio is set in advance and the actual speed ratio _NT / N is set.
By performing feedback control of the engagement state of the UD clutch 22 so that _E matches the target speed ratio, the control state of the automatic transmission approaches the neutral state, and the load on the engine is reduced.

[0007]

By the way, in order to bring the automatic transmission closer to the neutral state and to achieve the effect of the neutralization such as the improvement of the fuel consumption and the reduction of the vibration, the target speed ratio should be as small as 1 ( _NT). = N _E ). However, when the speed ratio is increased, the UD clutch 22 is completely released, and it is necessary to re-engage the UD clutch 22 the next time the vehicle starts. The reconnection of the UD clutch 22 causes a start delay, which hinders a smooth start.

Therefore, in the idle neutral control, it is important to set the target speed ratio as close to the limit speed ratio as possible without exceeding the limit speed ratio at which the UD clutch 22 is released. Here, as the limit speed ratio, it is conceivable to use a speed ratio in a neutral state (no load state) such as when the shift speed is in the N range or the P range. If the target speed ratio is set to a value slightly smaller than the speed ratio in the neutral state, it is possible to control to a state close to the limit in the neutral state.

However, the speed ratio in the neutral state is not always constant. For example, automatic transmissions have mechanical friction, and the size of each automatic transmission varies. The viscosity of ATF (automatic transmission oil) in the torque converter 20 changes depending on the oil temperature. Therefore, the speed ratio in the neutral state greatly varies depending on the friction, the oil temperature, and the engine rotation speed.

As described above, in the case where the speed ratio largely varies, in order to prevent the release of the UD clutch 22, the target speed ratio may be set to be small with a certain margin with respect to the speed ratio in the neutral state. Conceivable. However, if the target speed ratio is set with such a margin, it is impossible to approach the neutral state as much as possible, and the effect of the idle neutralization such as improvement of fuel efficiency and reduction of vibration is sufficiently enhanced. You will not be able to do it.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and regardless of individual differences and operating conditions of an automatic transmission,
An object of the present invention is to provide a shift control device for an automatic transmission, which enables the automatic transmission to be brought close to a neutral state as much as possible.

[0012]

Therefore, in the transmission control device for an automatic transmission according to the present invention, when it is determined that the automatic transmission is at the neutral position, the learning means determines the engine rotational speed, the input shaft rotational speed, and the like. The speed ratio defined based on is learned. Then, the target speed ratio is set by the target speed ratio setting means based on the learned value, and when the vehicle is at the traveling position and the vehicle is stopped, the friction engagement element is set so that the speed ratio becomes the set target speed ratio. The engagement state is controlled by the control means.

Preferably, the temperature of the hydraulic oil in the fluid coupling is detected, and the learning means is provided with a plurality of learning areas assigned to each predetermined oil temperature and each predetermined engine speed. Then, the speed ratio is learned for each learning region corresponding to the detected oil temperature and engine rotation speed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 show a shift control device for an automatic transmission for a vehicle as one embodiment of the present invention, and FIG. 1 is a functional block diagram showing the configuration thereof. As shown in FIG. 1, the present speed change control device includes a TCU.
(Transmission control unit) 1
And a turbine rotation speed sensor (input shaft rotation speed detecting means) 12 for detecting the rotation speed _NT of the turbine shaft (input shaft) 21, a shift position switch 13 for detecting which shift position is selected, and the temperature of the ATF. An oil temperature sensor (oil temperature detecting means) for detecting T _OIL 14,
Equipped engine rotational speed sensor (engine rotational speed detecting means) 30 for detecting the rotational speed N _E of the engine, and various sensors such as a stop lamp switch 31 and the idle switch 32, and a hydraulic circuit 11 of the automatic transmission 10 It is configured.

FIG. 1 shows a case where the automatic transmission 10 performs four-speed shifting, and U is used as a friction element.
A D (under drive) clutch 22, an LR (low reverse) brake 23, a second brake 24, a reverse clutch 25, and an overdrive clutch 26 are provided. Note that the automatic transmission 10 has the same configuration as the conventional one, and the torque converter (fluid coupling) 2
0, a turbine shaft 21, an oil pump 29, and the like.

The TCU 1 includes these friction elements 22 to 26
Is controlled, and the shift speed is determined by the engagement state of each of the friction elements 22-26. In particular, the shift position is in the D range (forward position), and
When the vehicle is stopped, the UD clutch 22 and the LR brake 23 are engaged, and the first speed is selected. Then, when the shift position is in the D range and the vehicle is stopped, U
By appropriately controlling the coupling state of the D clutch 22,
An idle neutral control described later is performed.

The UD clutch 22 is controlled by the hydraulic circuit 11
Is to be carried out through. That is, the hydraulic circuit 11 is provided with a solenoid valve (not shown) for supplying ATF to the UD clutch 22, and the solenoid valve is provided with a drive signal (duty ratio signal) from a clutch control means (control means) 2, which is a functional element of the TCU 1. ) To drive the solenoid valve appropriately,
The amount of TF is adjusted. ATF
Is adjusted to a predetermined oil pressure (line pressure) by a regulator valve (not shown), and A is adjusted to this line pressure.
The TF is supplied to the hydraulic circuit 11 that operates the UD clutch 22.

Here, the control content of the idle neutral control of the automatic transmission 10 by the present shift control device will be described. In the present shift control device, when the shift speed is in the neutral position, that is, when the shift position is in the N range or the P range, The speed ratio ( _NT / _NE ) is learned, and the shift position becomes D
When the vehicle is in the range and the vehicle is stopped, the target speed ratio is set based on the learned speed ratio, and the UD clutch 22 is controlled so that the actual speed ratio becomes the set target speed ratio to approach the neutral state. Like that.

For this reason, the TCU 1 has, in addition to the clutch control means 2 described above, judging means 3, learning means 4, and target speed ratio setting means 5 as its functional elements. The idle neutral control is performed through the control unit. Hereinafter, with reference to the flowcharts of FIGS. 2 to 4, each functional element relating to idle neutral control and the control content thereof will be described.

As shown in FIG. 2, in the TCU 1, first,
The determination means 3 determines the start of learning of the speed ratio. The start of learning of the speed ratio is determined based on whether the following four conditions are satisfied. The first condition is that the gear position is in the neutral position, that is, the N range or the P range is set as the shift position. (Step S
100). The second to fourth conditions are conditions for obtaining a highly accurate learning value, and the second condition is that the engine speed N
_E is not varying significantly [e.g., fluctuation width of the engine rotational speed N _E is within a predetermined value (e.g., ± 50 rpm)] is that. The third condition is that the oil temperature T _OIL is within a normal range (for example, −15 ° C. ≦ T _OIL ≦ 120 ° C.), and the fourth condition is that the engine speed _NE is within the idle speed range. (e.g., 450rpm ≦ N _E ≦ 130
0 rpm). The determination means 3 determines to start learning the speed ratio when all of these conditions are satisfied (step S110).

The start of learning of the speed ratio is established by the judging means 3.
Is determined, learning of the speed ratio is performed by the learning means 4.
Now. Here, the speed ratio (learning speed ratio) E_SInitial settings
Speed ratio E_SOAnd learning value E_SLIs set as the sum of
Learning value E_SLLearning correction. Ma
In the learning means 4, the engine speed N_EAnd oil temperature T_OI
LIs divided into a matrix with
It has a number of learning areas (RAM, etc.)
Engine rotation speed N_EAnd oil temperature T_OILLearning value E for each _SLLearn
Make corrections and store them in the corresponding area (RAM)
Has become.

[0022] First, the learning unit 4 detects the engine rotational speed N _E and the oil temperature T _OIL in a predetermined period (step S
120), detected engine speed _NE and oil temperature T
It reads the learned value E _SL from learning region corresponding to _OIL up to the last time by calculating the learning speed ratio _{E S (E S = E SO} + E SL) ( step S130). Then, an average speed ratio (actual speed ratio) E _SREAL for a predetermined time (for example, one second) within the measurement cycle.
Is measured (step S140), and the actual speed ratio E
The difference between the _SREAL and learning speed ratio _{E S ΔE S (ΔE S =} E SR
_EAL -E _S) by calculating (step S150), the correction amount of the correction amount (learned value corresponding to the difference Delta] E _S) to determine a Delta] E _SL (step S160). The correction amount ΔE _SL may be linear with respect to the difference ΔE _S , but here, as shown in FIG. 5, weighting is performed by setting the correction amount ΔE _SL in a stepwise manner with respect to the difference ΔE _S. . Then, the determined correction amount ΔE _SL is added to the previous learning value (E _S ) _OLD to be updated, and the updated learning value (E _S ) _NEW [(E _S ) _NEW
= (E _S ) _OLD + ΔE _SL ] Is stored in the corresponding learning area (step S170).

The above steps S120 to S170 are repeated until the learning start condition (steps S100 and S110) is not satisfied. When the learning start condition is not satisfied, the process proceeds to step 200 in FIG. Then, the determination means 3 determines the start of the idle neutral control. The start of the idle neutral control is determined by whether or not the following five conditions are satisfied. The first condition is that the gear position is in the forward position, that is, the travel range (ie, the D range) as the shift position. Or 3,
2, L range) is selected (step S200).

When the first condition is satisfied, the other four start conditions (second to fifth conditions) are determined. 2nd, 3rd
Is a condition for determining whether the vehicle is stopped or not, the vehicle speed is zero (or extremely low speed) (second condition), and the brake is depressed (third condition). Sometimes it is determined that the vehicle is stopped. Whether the vehicle speed is zero or is determined by whether the output shaft rotation speed N _O is in a predetermined time zero, determined by whether the whether the brake is depressed the stop lamp switch 31 is turned on I do. It should be noted that the output shaft rotation speed N _O is the turbine rotation speed N
It may be calculated based on _T , or may be calculated from another element corresponding to the vehicle speed. Fourth, fifth condition the aforementioned learning condition (third, fourth condition) are those which correspond to the oil temperature T _OIL, the engine rotational speed N _E with the proviso that within learning the aforementioned range . However, the control start range here is set slightly narrower than the above-described learning range to improve the learning accuracy. For example, if the learning range is the above-described example range, the oil temperature T _OIL is −10 ° C. ≦ T _OIL ≦
The 115 ° C. and control start range (fourth condition), 550rpm ≦ N _E ≦ 1200rp for engine rotational speed N _E
m is the control start range (step S21).
0).

When the start of the idle neutral control is determined by the determining means 3, the idle neutral control in step S220 is performed until the release of the idle neutral control is determined. FIG. 4 shows the flow of the idle neutral control. First, in steps S300 to S330, the target speed ratio setting unit 5 learns the speed ratio (learning speed ratio) E learned by the learning unit 4.
_The target speed ratio _EST is set based on _S.

The target speed ratio setting means 5 first detects the engine speed N _E and the oil temperature T _OIL (step S30).
0), the detected engine rotational speed N _E, a learning region corresponding to the oil temperature T _OIL reads the learned value E _SL (step S
310), the read learning value E _SL is set to the initial set speed ratio E _SO
To the learning speed ratio E _S (E _S = E _SO + E
_SL ) is calculated (step S320). Then, a predetermined margin K _E (for example, K _E = 90 to 9) is added to the learning speed ratio E _S.
5%), the target speed ratio E _ST (E _ST = K
_E × E _S ) is set (step S330).

When the target speed ratio E _ST is set, the clutch control means 2 causes the clutch control means 2 to set U to idle neutral.
The control of the D clutch 22 is started (Step S34)
0). Explaining this control content with reference to FIG. 6, the clutch control means 2 determines that the start of the idle neutral control is determined by the determination means 3 (time point S).
S), first, the extent to which the predetermined value of the duty ratio of the solenoid of the UD clutch 22 from 100% (UD clutch 22 is not Dasa slip, for example, reduced to 40%) D _N. Then, gradually reduce the duty ratio at a predetermined change rate dD _N.

By reducing the duty ratio of the solenoid, the hydraulic pressure applied to the UD clutch 22 gradually decreases from the line pressure, and then the UD clutch 22 starts to slide when the hydraulic pressure decreases to a predetermined hydraulic pressure. become. When the UD clutch 22 starts to slide, the turbine shaft 21 starts to rotate, and the turbine rotation speed N
_T gradually rises.

Then, the turbine rotation speed _NT becomes a predetermined value Δ
When the duty ratio has increased to N _B (time SB), the duty ratio is increased by ΔD _B and thereafter, until the determination means 3 determines that the idle neutral control is released (time E).
S), performing feedback control. In the feedback control, the duty ratio is changed based on the deviation between the actual speed ratio E _s (E _s = N _T / N _E ) and the target speed ratio E _ST, and the actual speed ratio E _s becomes the target speed ratio E _ST . The connection state of the UD clutch 22 is controlled so as to be as follows.

The processing in steps S300 to S340 is repeated until the condition for canceling the idle neutral control is satisfied. When the condition for canceling the idle neutral control is satisfied, the process proceeds to step 240 in FIG. The conditions for releasing the idle neutral control are the following six. The first condition is that the gear position is set to a position other than the forward position, that is, a position other than the D range (or 3, 2, L range) is selected as the shift position. The second to fourth conditions are conditions for determining whether or not the vehicle has started, and the vehicle speed is zero (second condition).
Condition), the brake is not applied (third condition),
It is determined that the vehicle has started when the accelerator pedal is depressed (fourth condition). Here, the output shaft rotation speed N
_O exceeds a predetermined value (for example, 90 rpm), the stop lamp switch 31 is turned off, and the idle switch 32
Each condition is satisfied when is turned off.
The fifth and sixth conditions are the aforementioned learning conditions (third and fourth conditions).
To are those corresponding oil temperature T _OIL, and the engine rotational speed N _E is the cancellation condition that falls outside the learning ranges mentioned above. That is, assuming that the learning range is the above-described example range, the oil temperature T _OIL is T _OIL <−15 ° C., 12
0 ° C. <when it becomes T _OIL (fifth condition), N _E for the engine rotational speed N _E <450rpm, 1300rpm
<It releases the control to the (sixth condition) when it is N _E.

After the idle neutral control is released, control for transition to normal control (neutralization escape control) is performed (step S240). This neutral escape control is similar to the control (ND control) performed when the shift position is changed from the N range to the D range, and as shown in FIG. 6, the duty ratio of the solenoid of the UD clutch 22 is changed. Gradually increase, UD
The hydraulic pressure applied to the clutch 22 is increased to gradually reduce the turbine rotational speed _NT . Then, when the turbine rotation speed _NT decreases to a certain degree, the duty ratio is set to 100%, and the UD clutch 22 is completely engaged (time SF).

As described above, according to the shift control device for an automatic transmission according to one embodiment of the present invention, every time the N range or the P range is selected and the neutral state (no load state) is reached, the speed at that time is set. Since the ratio is learned and the target speed ratio is set based on the learned speed ratio, during idle neutral control, it is possible to always control the vehicle to a state close to the neutral state, and release the UD clutch. It is possible to improve the fuel efficiency and reduce the vibration without causing the vibration. Also, the learning of speed ratios in the neutral state, the engine rotational speed N _E, since thereby performing for each oil temperature T _OIL, the engine rotational speed N _E, the oil temperature T
Without being affected by variations in speed ratio due to _OIL ,
Highly accurate control is always possible.

It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the spirit of the present invention. For example, the automatic transmission may be a continuously variable transmission (CVT) instead of the gear type as shown in the above embodiment. In this case, idle neutralization is performed by controlling the coupling state of the forward clutch or the reverse brake instead of the UD clutch.

[0034]

As described above in detail, according to the shift control device for an automatic transmission of the present invention, the limit is always in the neutral state at the time of the idle neutral control irrespective of the individual difference and the operation state of the automatic transmission. Therefore, it is possible to improve fuel economy and reduce vibration without releasing the friction engagement element.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of a shift control device for an automatic transmission as one embodiment of the present invention.

FIG. 2 is a diagram showing a flow of idle neutral control according to a shift control device for an automatic transmission as one embodiment of the present invention.

FIG. 3 is a diagram showing a flow of idle neutral control according to a shift control device for an automatic transmission as one embodiment of the present invention.

FIG. 4 is a diagram showing a flow of idle neutral control according to a shift control device for an automatic transmission as one embodiment of the present invention.

FIG. 5 is a diagram illustrating a method of setting a correction amount of a learning speed ratio according to the shift control device of the automatic transmission as one embodiment of the present invention.

FIG. 6 is a diagram showing control timing of idle neutral control according to a shift control device for an automatic transmission according to an embodiment of the present invention.
_E , a diagram showing the time change of the turbine rotation speed _NT , (b)
FIG. 7 is a diagram illustrating control timing of a duty ratio of a solenoid that drives a UD clutch, and FIG. 7C is a diagram illustrating a temporal change of a hydraulic pressure of the UD clutch.

[Explanation of symbols]

2 Clutch control means (control means) 3 Judgment means 4 Learning means 5 Target speed ratio setting means 10 Automatic transmission 12 Turbine rotation speed sensor (input shaft rotation speed detection means) 20 Torque converter (fluid coupling) 21 Turbine shaft (input shaft) 22) UD clutch (friction engagement element) 30 Engine speed sensor (engine speed detecting means)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hoshi Kojima 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation F-term (reference) 3J052 AA04 AA14 CB11 FA03 GC33 GC42 GC44 GC64 GC72 GC73 HA02 KA02 LA01

Claims (1)

[Claims] 1. An automatic transmission having a friction engagement element connected to an engine via an input shaft via a fluid coupling, and capable of connecting and disconnecting transmission of driving force input from the engine to the input shaft to driving wheels. A shift control device for an automatic transmission, a determination unit that determines whether the automatic transmission is at a traveling position or a neutral position, an engine rotation speed detection unit that detects a rotation speed of the engine, and a rotation speed of the input shaft. Input shaft rotational speed detecting means for detecting the neutral position, and learning means for learning a speed ratio defined based on the engine rotational speed and the input shaft rotational speed when the automatic transmission is at the neutral position. Target speed ratio setting means for setting a target speed ratio which is a target value of the speed ratio when the automatic transmission is at the traveling position and the vehicle is in a stopped state, based on the learned value of the speed ratio at The automatic transmission runs And control means for controlling an engagement state of the friction engagement element so that the speed ratio becomes the target speed ratio set by the target speed ratio setting means when the vehicle is at a stop position. Characterized by the fact that
Transmission control device for automatic transmission.