JP3680641B2 - Shift control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for an automatic transmission suitable for use in an automobile.
[0002]
[Prior art]
An automatic transmission provided in an automobile or the like has friction engagement elements such as a plurality of hydraulic clutches and hydraulic brakes inside, and various controls such as achievement of a predetermined shift stage by appropriately releasing and connecting them. Is possible. 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]
Idle neutral control means that even when the shift position of the automatic transmission is in the D range (traveling position), when the vehicle is stopped (mainly when the brake is operating) (that is, idling in a broad sense). (When in the state), the control is to bring the gear closer to the neutral state as in the N range (neutral position) or P range (parking position), and aims to improve fuel consumption and reduce vibration.
[0004]
The idle neutral control will be specifically described below with reference to the skeleton diagram in FIG. The configuration of the automatic transmission shown in the skeleton diagram is the same as that of the conventional one and is not a characteristic part of the present invention.
Normally, when the shift position is in the D range and the vehicle is stopped, the first gear is selected as the gear position, and therefore, among the friction engagement elements 22 to 26, the UD (underdrive) clutch 22, The LR (low / reverse) brake 23 is engaged, but the vehicle stops, that is, the tire is stopped. As a result, the turbine shaft 21 is restrained from rotating and the turbine 27 is stationary. On the other hand, since the pump impeller 28 rotates together with the engine, slip 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 engine load, resulting in worse fuel consumption and increased vibration.
[0005]
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 is allowed to rotate. As a result, slippage between the pump impeller 28 and the turbine 27 is reduced, and the engine load 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 of the engine is gradually reduced.
[0006]
Therefore, in the idle neutral control, a target speed ratio is set in advance, and the coupling state of the UD clutch 22 is feedback controlled so that the actual speed ratio N _T / N _E matches the target speed ratio. The control state is made closer to the neutral state to reduce the engine load.
[0007]
[Problems to be solved by the invention]
By the way, it is desirable to make the target speed ratio as close to 1 (N _T = N _E ) as possible in order to bring the automatic transmission closer to the neutral state and increase the effects of neutralization such as improvement of fuel consumption and reduction of vibration. . However, if the speed ratio is increased, the UD clutch 22 is completely released, and the UD clutch 22 needs to be re-coupled when the vehicle next starts. The re-engagement of the UD clutch 22 causes a delay in starting and hinders smooth starting.
[0008]
Therefore, in the idle neutral control, it is important to set the target speed ratio as close to the limit speed ratio as possible within a range not 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) as when the gear position 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 becomes possible to control the state close to the limit in the neutral state.
[0009]
However, the speed ratio in the neutral state is not always constant. For example, an automatic transmission has mechanical friction, and its size varies from individual to individual. Further, the viscosity of the ATF (automatic transmission oil) in the torque converter 20 varies depending on the oil temperature. Therefore, the speed ratio in the neutral state varies greatly depending on the friction, the oil temperature, and the engine speed.
[0010]
As described above, when the speed ratio varies greatly, it is conceivable to set the target speed ratio to be small with a certain margin with respect to the speed ratio in the neutral state in order to prevent the UD clutch 22 from being released. However, if the target speed ratio is set with a margin in this way, it is impossible to bring it to the neutral state as much as possible, and the effects of idle neutralization such as improvement of fuel consumption and reduction of vibration can be sufficiently increased. It becomes impossible to do.
[0011]
The present invention has been devised in view of such problems, and it is possible to shift the automatic transmission to the neutral state as much as possible regardless of individual differences and driving conditions of the automatic transmission. An object is to provide a control device.
[0012]
[Means for Solving the Problems]
Therefore, in the shift control device for an automatic transmission according to the present invention, when it is determined that the automatic transmission is in the neutral position, the learning means learns the speed ratio defined based on the engine rotation speed and the input shaft rotation speed. To do. Then, based on this learning value, the target speed ratio is set by the target speed ratio setting means. When the vehicle is stopped at the travel position, 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.
[0013]
Moreover , while detecting the oil temperature of the hydraulic fluid in a fluid coupling, the learning means is provided with a plurality of learning areas assigned for each predetermined oil temperature and for each predetermined engine speed. Then, the speed ratio is learned for each learning region corresponding to the detected oil temperature and engine rotation speed.
Preferably, the learning means starts learning the speed ratio when it is satisfied that the detected oil temperature is in the normal range and the detected engine rotation speed is in the idle rotation speed range.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 6 show a shift control apparatus for an automatic transmission for an automobile as an embodiment of the present invention, and FIG. 1 is a functional block diagram showing the configuration thereof.
As shown in FIG. 1, the transmission control apparatus includes a TCU (transmission control unit) 1 and a turbine rotation speed sensor (input shaft rotation speed detection means) that detects a rotation speed _NT of a turbine shaft (input shaft) 21. ) 12, an engine rotational speed detecting any shift position switch 13 that the shift position to detect whether a selected, ATF oil temperature sensor for detecting the temperature T _oIL of the (oil temperature detecting means) 14, the rotational speed N _E of the engine Various sensors such as a sensor (engine speed detection means) 30, a stop lamp switch 31, an idle switch 32, and the like, and a hydraulic circuit 11 of the automatic transmission 10 are configured.
[0015]
Further, FIG. 1 shows a case where the automatic transmission 10 is a four-speed shift, and UD (underdrive) clutch 22, LR (low / reverse) brake 23, second brake 24, reverse clutch 25, An overdrive clutch 26 is provided. The automatic transmission 10 has the same configuration as the conventional one, and includes a torque converter (fluid coupling) 20, a turbine shaft 21, an oil pump 29, and the like.
[0016]
The TCU 1 controls the engagement state of the friction elements 22 to 26, and the gear position is determined by the engagement state of the friction elements 22 to 26. In particular, when the shift position is in the D range (forward position) and the vehicle is stopped, the UD clutch 22 and the LR brake 23 are engaged and the first gear is selected. Then, when this shift position is in the D range and the vehicle is stopped, the idle neutral control described later is performed by appropriately controlling the coupling state of the UD clutch 22.
[0017]
The control of the UD clutch 22 is performed via the hydraulic circuit 11. 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 rate signal) from the clutch control means (control means) 2 which is a functional element of the TCU1. ) Is appropriately driven to adjust the amount of ATF. The ATF is regulated to a predetermined hydraulic pressure (line pressure) by a regulator valve (not shown), and the ATF regulated to this line pressure is supplied to the hydraulic circuit 11 that operates the UD clutch 22. ing.
[0018]
Here, the control contents of the idle neutral control of the automatic transmission 10 by the present shift control device will be described. In this shift control device, when the shift stage is in the neutral position, that is, when the shift position is in the N range or P range, the speed ratio ( N _T / N _E ), when the shift position is in the D range and the vehicle is stopped, the target speed ratio is set based on the learned speed ratio, and the actual speed ratio is set to the set target speed ratio. Thus, the UD clutch 22 is controlled so as to approach the neutral state.
[0019]
For this reason, the TCU 1 is provided with determination means 3, learning means 4, and target speed ratio setting means 5 as functional elements in addition to the clutch control means 2 described above, and idles via these functional elements 2-5. Neutral control is performed. Hereinafter, each functional element related to the idle neutral control and the contents of the control will be described with reference to the flowcharts of FIGS.
[0020]
As shown in FIG. 2, in the TCU 1, the determination unit 3 first determines the start of speed ratio learning. The start of learning of the speed ratio is determined based on whether or not 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 the shift position. That is, it is selected (step S100). Second to fourth condition is a condition for obtaining a highly accurate learned value, the second condition, the engine rotational speed N _E is not vary significantly [e.g., the fluctuation width of the engine rotational speed N _E It is within a predetermined value (for example, ± 50 rpm)]. 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 rotational speed _NE is within an idle rotational speed range. (For example, 450 rpm ≦ N _E ≦ 1300 rpm). The judging means 3 judges that the learning of the speed ratio is started when all these conditions are satisfied (step S110).
[0021]
When the determination means 3 determines that the learning start of the speed ratio is established, the learning means 4 learns the speed ratio. Here, has set the speed ratio (learning speed ratio) E _S as the sum of the initial set speed ratio E _SO and the learned value E _SL, the learning value E _SL is adapted to the learning correction. Further, the learning means 4 has a plurality of learning regions (such as RAM) divided in a matrix using the engine speed N _E and the oil temperature T _OIL as parameters, and the detected engine speed N _E and the detected oil temperature. The learning value _ESL is learned and corrected for each T _OIL and stored in the corresponding area (RAM).
[0022]
First, the learning unit 4, at a predetermined cycle and detects the engine rotational speed N _E and the oil temperature T _OIL (step S120), corresponding to the detected engine rotational speed N _E and the oil temperature T _OIL from learning region up to the last time The learning value E _SL is read out and the learning speed ratio E _S (E _S = E _SO + E _SL ) is calculated (step S130). Then, the average speed ratio (actual speed ratio) E _SREAL predetermined time in the measuring period (e.g. one second) measured (step S140), further difference Delta] E _S between the actual speed ratio E _SREAL the learning speed ratio E _S ( to calculate the _{ΔE S = E SREAL -E S)} ( 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). Correction Delta] E _SL may be linear with respect to the difference Delta] E _S, but here, as shown in FIG. 5, are subjected to weighting by setting stepwise the correction amount Delta] E _SL relative difference Delta] E _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).
[0023]
The processes in steps S120 to S170 are repeated until the learning start condition (steps S100 and S110) is not established. When the learning start condition is not established, the process proceeds to step 200 in FIG. And the determination means 3 determines the start of idle neutral control. The start of the idle neutral control is determined based on whether or not the following five conditions are satisfied. The first condition is that the shift stage is in the forward position, that is, the shift range is the travel range (that is, the D range). , Or 3, 2, L range) is selected (step S200).
[0024]
When the first condition is satisfied, the other four start conditions (second to fifth conditions) are determined. The second and third conditions are conditions for determining whether or not the vehicle is stopped, the vehicle speed is zero (or very low speed) (second condition), and the brake is depressed ( (Third condition) When it is determined that the vehicle is stopped. Whether or not the vehicle speed is zero is determined based on whether or not the output shaft rotational speed N _O is zero for a predetermined time, and whether or not the brake is depressed is determined based on whether or not the stop lamp switch 31 is turned on. To do. Note that the output shaft rotational speed N _O may be calculated based on the turbine rotational speed _NT or may be calculated from other elements 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 aforementioned learning range to increase the learning accuracy. For example, if the learning range is the above-described exemplary range, the oil temperature T _OIL is −10 ° C. ≦ T _OIL ≦ 115 ° C. is set as the control start range (fourth condition), and the engine rotation speed N _E is set as 550 rpm ≦ N _E ≦ 1200 rpm (step S210).
[0025]
When it is determined by the determination means 3 that the idle neutral control is started, the idle neutral control in step S220 is performed until it is determined that the idle neutral control is canceled. The flow of idle neutral control is shown in FIG. 4. First, in steps S300 to S330, the target speed based on the speed ratio (learning speed ratio) E _S learned by the learning means 4 by the target speed ratio setting means 5 is shown. Set the ratio E _ST .
[0026]
The target speed ratio setting means 5 first detects the engine speed N _E and the oil temperature T _OIL (step S300), and learns the value E _SL from the learning region corresponding to the detected engine speed N _E and the oil temperature T _OIL. Is read (step S310), and the learning speed ratio E _S (E _S = E _SO + E _SL ) is calculated by adding the read learning value E _SL to the initially set speed ratio E _SO (step S320). Then, the target speed ratio E _ST (E _ST = K _E × E _S ) is set by multiplying the learning speed ratio E _S by a predetermined margin rate K _E (for example, K _E = 90 to 95%) (step S330).
[0027]
When the target speed ratio E _ST is set, the clutch control unit 2 starts control of the UD clutch 22 for idle neutralization (step S340). This control content will be described with reference to FIG. 6. When the determination unit 3 determines that the idle neutral control is started (time SS), the clutch control unit 2 first sets the duty ratio of the solenoid of the UD clutch 22 to 100. (degree to which UD clutch 22 is not Dasa slip, for example, 40%) predetermined value from% reduced to D _N. Then, gradually reduce the duty ratio at a predetermined change rate dD _N.
[0028]
By reducing the duty ratio of the solenoid, the hydraulic pressure applied to the UD clutch 22 gradually decreases from the line pressure, and the UD clutch 22 starts to slip when it eventually decreases to a predetermined hydraulic pressure. As the UD clutch 22 starts to slide, the turbine shaft 21 starts to rotate, and the turbine rotational speed _NT gradually increases.
[0029]
Then, when the turbine rotational speed N _T is increased to a predetermined value .DELTA.N _B (time SB), it increases the duty ratio by [Delta] D _B, until thereafter, the determination unit 3 releases the idle neutral control is determined (time ES) , Feedback control is performed. In 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 so that the actual speed ratio E _s becomes the target speed ratio E _ST . Thus, the coupling state of the UD clutch 22 is controlled.
[0030]
The processes in steps S300 to S340 are repeated until the release condition for idle neutral control is satisfied. When the release condition is satisfied, the process proceeds to step 240 in FIG. There are six conditions for canceling the idle neutral control as follows. The first condition is that the gear position is other than the forward position, that is, a range 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, the vehicle speed is zero (second condition), the brake is not depressed (third condition), When the accelerator pedal is depressed (fourth condition), it is determined that the vehicle has started. Here, it is assumed that each condition is satisfied when the output shaft rotational speed N _O becomes a predetermined value (for example, 90 rpm) or more, the stop lamp switch 31 is turned off, and the idle switch 32 is turned off. Fifth, the conditions of the sixth aforementioned learning condition (third, fourth condition) are those which correspond to the release that the oil temperature T _OIL, and the engine rotational speed N _E is out learning the aforementioned range condition It is said. That is, assuming that the learning range is the above-described exemplary range, when the oil temperature T _OIL is T _OIL <−15 ° C. and 120 ° C. <T _OIL (fifth condition), the engine speed N _{E is} about Control is canceled when N _E <450 rpm and 1300 rpm <N _E (sixth condition).
[0031]
After the idle neutral control is canceled, control for shifting to normal control (neutralization escape control) is performed (step S240). This neutralization escape control is the same control as that performed when the shift position is changed from the N range to the D range (ND control), and as shown in FIG. 6, the duty ratio of the solenoid of the UD clutch 22 Is gradually increased, the hydraulic pressure applied to the UD clutch 22 is increased, and the turbine rotational speed _NT is gradually decreased. When the turbine rotational speed _NT decreases to a certain level, the duty ratio is set to 100% and the UD clutch 22 is completely coupled (time point SF).
[0032]
Thus, according to the shift control device for an automatic transmission according to an embodiment of the present invention, every time the N range or the P range is selected and the neutral state (no load state) is entered, the speed ratio at that time is learned. In addition, since the target speed ratio is set based on the learning speed ratio, it is possible to always control the state close to the neutral state during idle neutral control, and to release the UD clutch. It is possible to improve fuel consumption and reduce 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 influence of variations in the speed ratio due to the oil temperature T _OIL High accuracy control is always possible without receiving it.
[0033]
The present invention is not limited to the above-described embodiment, and various modifications can be made 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]
【The invention's effect】
As described above in detail, according to the shift control device for an automatic transmission of the present invention, during idle neutral control, control is always made to be close to the neutral state regardless of individual differences and operating states of the automatic transmission. It is possible to improve the fuel consumption and reduce the 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 according to an embodiment of the present invention.
FIG. 2 is a diagram showing a flow of idle neutral control according to the shift control device of the automatic transmission as one embodiment of the present invention.
FIG. 3 is a diagram showing a flow of idle neutral control according to the shift control device of the 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 an embodiment of the present invention.
FIG. 5 is a diagram illustrating a method for setting a correction amount for a learning speed ratio according to a shift control device for an automatic transmission according to an embodiment of the present invention.
FIG. 6 is a diagram showing the control timing of idle neutral control according to the shift control device of the automatic transmission as one embodiment of the present invention, where (a) is the time of engine rotation speed N _E and turbine rotation speed _NT . FIG. 5B is a diagram showing a control timing of a duty ratio of a solenoid that drives a UD clutch, and FIG. 5C is a diagram showing a temporal change in hydraulic pressure of the UD clutch.
[Explanation of symbols]
2 Clutch control means (control means)
3 Determination means 4 Learning means 5 Target speed ratio setting means 10 Automatic transmission 12 Turbine rotational speed sensor (input shaft rotational speed detection means)
20 Torque converter (fluid coupling)
21 Turbine shaft (input shaft)
22 UD clutch (friction engagement element)
30 Engine rotation speed sensor (Engine rotation speed detection means)

Claims (2)

A shift control device for an automatic transmission having a frictional engagement element connected to an engine via a fluid coupling and capable of connecting / disconnecting transmission of driving force input from the engine to the driving wheel to the driving wheel In
Determining means for determining whether the automatic transmission is in a traveling position or a neutral position;
Engine rotation speed detection means for detecting the rotation speed of the engine;
Input shaft rotational speed detection means for detecting the rotational speed of the input shaft;
Oil temperature detecting means for detecting the oil temperature of the hydraulic oil in the fluid coupling;
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 in a neutral position;
A target speed ratio setting that sets a target speed ratio that is a target value of the speed ratio when the automatic transmission is at the traveling position and the vehicle is stopped based on the learned value of the speed ratio at the neutral position. Means,
When the automatic transmission is at the traveling position and the vehicle is stopped, the engagement state of the friction engagement element is controlled so that the speed ratio becomes the target speed ratio set by the target speed ratio setting means. and a control means that,
The learning means is provided with a plurality of learning regions divided into a matrix using the oil temperature and the engine speed as parameters, and the learning means detects the oil temperature detected by the oil temperature detection means. A speed change control device for an automatic transmission, wherein the speed ratio is learned for each learning region corresponding to the engine speed detected by the engine speed detecting means . The learning means is such that the oil temperature detected by the oil temperature detecting means is within a normal range, and the engine rotational speed detected by the engine rotational speed detecting means is within an idle rotational speed range. Start learning the speed ratio when satisfied
The shift control apparatus for an automatic transmission according to claim 1, wherein:

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