JP2000065195A - Controller of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent or reduce lack of driving force on an upward slope by providing a gradient detecting means for detecting values on a gradient of a traveling passage, and prohibiting fastening of a lockup clutch in preference to a lockup control means when detecting that the traveling passage is the upward slope. SOLUTION: Respective sensor signals of a sensor 11 for detecting an accelerator stepping quantity, that is accelerator opening, a sensor 12 for detecting a vehicle speed, a sensor 13 for detecting actuation of a brake and a sensor 14 for detecting a present gear position, that is, a shift stage of an automatic transmission 2, are inputted to a control unit 10. When an automobile travels, a degree of a gradient is known by using a map prestoring anticipated acceleration on a flat passage (a gradient is zero) by using the accelerator stepping quantity and the vehicle speed as a parameter. When a gradient of a traveling passage is judged as an upward gradient larger than a predetermined value, fastening of a lockup clutch by a lockup solenoid 5 is prohibited to eliminate lack of driving force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for an automatic transmission.

[0002]

2. Description of the Related Art In an automatic transmission, shift control is performed based on predetermined shift characteristics. When the automatic transmission is for a vehicle, the shift characteristics are generally created using both the engine load and the vehicle speed as parameters. A plurality of types of shift characteristics are prepared, for example, two types of the economy mode and the power mode in which the speed is shifted at a vehicle speed higher than the economy mode are prepared, and the driver performs manual operation. In this way, any desired shift characteristic can be arbitrarily selected.

As described above, the shift characteristics (hereinafter referred to as first shift characteristics or basic shift characteristics) in which the engine load and the vehicle speed are set as parameters are as follows.
The vehicle speed at the time of shifting is increased as the engine load is increased. In general, such a basic shift characteristic is generally set as suitable for traveling on a flat ground, that is, a traveling road with a not so large gradient.

When traveling on a traveling road with a large gradient, the first
If the speed change control is performed based on the speed change characteristics, the driving force tends to be insufficient (in the case of an upward gradient), or it is difficult to secure a sufficient engine brake (in the case of a downward gradient). Therefore, conventionally, as shown in Japanese Patent Application Laid-Open No. 56-97564, when the gradient of the traveling road is large, only the shift line when the engine load is the maximum (corresponding to full throttle opening) among the basic shift characteristics is used. A gear shift control is proposed. In this manner, the above-described situation of insufficient driving force can be solved by setting the upper limit of the vehicle speed set by the shift line having the first shift characteristic as the actual shift line (second shift characteristic). .

On the other hand, automatic transmissions are often connected to an engine via a torque converter, and many of these torque converters have a lock-up clutch for directly connecting a pump and a turbine. . The control of engagement and disengagement of the lock-up clutch is performed based on a preset lock-up characteristic. Various lock-up characteristics have been proposed in the past, but generally, the lock-up clutch is engaged when the vehicle speed is equal to or higher than a predetermined vehicle speed. As described above, in the control of the automatic transmission, the lock-up control unit that controls the engagement and disengagement of the lock-up clutch based on the lock-up characteristic separately from the shift control unit that performs the shift control based on the shift characteristic. Is usually provided with

[0006]

[Problems to be solved by the invention]

[0007] By the way, a mountain road in which a large ascending slope and a descending slope are repeated, that is, a mountain road in which ups and downs are continuous, has a continuous corner (curve) as a so-called winding road. I do. In such a winding load, it is possible to drive at a considerably high speed, so that a large acceleration / deceleration occurs every time the vehicle passes through the curve. This acceleration / deceleration is ultimately caused by a large change in the accelerator pedal depression amount. A large change in the accelerator pedal depression amount results in a large change in the engine load that determines the shift characteristics. Therefore, in the winding load, the gear is shifted for each curve, that is, the gear is shifted down (deceleration) just before the curve and up (accelerated) in the middle or at the end of the curve. In addition, since the curves are continuously present, the shift-down and the shift-up are frequently repeated.

As described above, the frequent repetition of shifting in the winding load may mean that the lock-up clutch is frequently engaged and disengaged. In particular, when the vehicle is running on a steep uphill, the driving force tends to be insufficient at the speed set based on the first speed change characteristic, but when the lock-up clutch is engaged, the torque converter cannot be expected to increase the torque. As a result, the tendency of insufficient driving force is further promoted.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an automatic transmission that performs optimal lock-up control so that shortage of driving force can be prevented or reduced on an uphill. The purpose of the present invention is to provide a machine control device.

[0010]

Means for Solving the Problems To achieve the above object, the present invention has the following configuration. That is, a lock that includes a torque converter with a lock-up clutch and controls the engagement and disengagement of the lock-up clutch based on a preset lock-up characteristic, as described in claim 1. In a control device for an automatic transmission provided with an up control means, a gradient detecting means for detecting a value relating to a gradient of a traveling path, and an output from the gradient detecting means is detected, and it is detected that the traveling path is uphill. And a prohibiting means for prohibiting engagement of the lock-up clutch prior to the lock-up control means.

Although switching shocks occur at least when the lock-up clutch is switched between engagement and disengagement, the disengagement of the lock-up caused by the operation of the prohibiting means does not give a feeling of strangeness to the driver. As described in claim 2, it is possible to set the prohibiting means to be activated on condition that the downshift is detected.

[0012]

According to the first aspect of the present invention, when the vehicle travels on an uphill, the lock-up clutch is forcibly prohibited by the prohibiting means to maintain the disengaged state. As a result, the driving state is such that the torque increasing effect of the torque converter is sufficiently exhibited, and the shortage of the driving force can be prevented or reduced. Further, forcibly maintaining the lock-up clutch in the disengaged state by the prohibition means reduces the chance of switching between the engagement and disengagement of the lock-up clutch, that is, the opportunity for the occurrence of a shock due to the switching. It is also preferable in terms of reducing the amount. According to the second aspect of the present invention, by operating the prohibiting means also on condition that a downshift is detected, the lock-up clutch is released from the engaged state due to the operation of the prohibiting means itself. Even in the case where the vehicle is switched to the disengaged state, the driver recognizes that the lock-up clutch is switched in synchronization with the change of the vehicle due to the acceleration, which is a sense of discomfort given to the driver. Things can be made smaller.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Overall Configuration In FIG. 1, 1 is an engine, 2 is an automatic transmission,
The output of the engine 1 is transmitted to drive wheels (not shown) via the automatic transmission 2. The automatic transmission 2 is a torque converter.
And a planetary gear type multi-stage transmission mechanism 4. The torque converter 3 is provided with a lock-up clutch (not shown), and the lock-up solenoid 5 is switched between energizing and de-energizing, thereby turning on the lock-up.
(Fastening) and OFF (release). Further, the speed change mechanism 4 has four forward speeds in the embodiment, and the desired speed is set by changing the combination of excitation and demagnetization of the plurality of speed change solenoids 6 as is known. Of course, each of the solenoids 5 and 6 switches the operation mode of the lock-up or speed-change hydraulic actuator. However, since these are well-known matters, they will not be described further. Description is omitted.

In FIG. 1, reference numeral 10 denotes a control unit constituted by using a microcomputer, to which signals from respective sensors or switches 11 to 15 are inputted. The sensor 11 detects an accelerator depression amount, that is, an accelerator opening. The sensor 12 detects a vehicle speed. The sensor 13 detects the operation of the brake. The sensor 14 detects a current gear position of the automatic transmission 2, that is, a gear position. Switch 15
Is for manually selecting one of a power mode and an economy mode, which will be described later, as a shift characteristic. The output from the control unit 10 is to the throttle actuator 7 and each of the solenoids 5 and 6. The throttle actuator 7 drives a throttle valve 8 provided in an intake passage of the engine 1, and the control unit 10 controls the actuator 7 so that the throttle opening corresponds to the accelerator depression amount. .

The control unit 10 basically has a CP
U, ROM, RAM, CLOCK (soft timer) and an A / D or D / A converter, as well as an input / output interface. These are known configurations using a microcomputer. Therefore, the description is omitted. The shift characteristics (map) used in the following description
And the like are stored in the ROM of the control unit 10.

Shift Characteristics Next, the shift characteristics used in this embodiment will be described with reference to FIG.
This will be described with reference to FIGS. As this shift characteristic,
Basically, the first shift characteristic is a basic shift characteristic created using the accelerator, the amount of load as an engine load, and the vehicle speed as parameters, and the second shift characteristic is a vehicle speed-sensitive shift characteristic created using only the vehicle speed as a parameter. It has two types of two-shift characteristics. Then, a power mode and an economy mode are set for both of these shift characteristics.

These shift characteristics will be described more specifically. FIGS. 2 and 3 show first shift characteristics, respectively.
2 shows the case of the economy mode, and FIG. 3 shows the case of the power mode. In the case of the power mode (FIG. 3), the shift is set at a higher vehicle speed than in the case of the economy mode (FIG. 2). On the other hand, FIGS. 4 and 5 show the second shift characteristic, respectively. FIG. 4 shows the case of the economy mode, and FIG. 5 shows the case of the power mode. The second shift characteristic is also set such that the shift is performed at a higher vehicle speed in the power mode (FIG. 5) than in the economy mode (FIG. 4).

Here, the second speed change characteristic will be described in detail in comparison with the first speed change characteristic, taking the case of the economy mode as an example. First, the second shift characteristic is defined as a range of an accelerator pedal depression amount (approximately 4/8) which is frequently used in a winding load.
(Lower than the opening), the shift line is set so that the shift is performed at a vehicle speed higher than the first shift characteristic (expansion of the low speed range region), and the road is often set to a winding road. The setting is made to cover the shortage of engine output due to running at (low air density). Further, the speed change line of the second speed change characteristic is set in consideration of the fact that the driving force is not excessively increased when the accelerator pedal depression amount becomes extremely large. That is, the upper limit of the vehicle speed that can be obtained in the first speed of the first speed change characteristic (FIG. 2) is about 50 km /
h is set to 30 km / h in the second shift characteristic (FIG. 4).

As described above, the intermediate speed is set to be an intermediate vehicle speed larger than the lower limit value and smaller than the upper limit value of the vehicle speed obtained by the speed change line in the first speed change characteristic. A shift line based on the second shift characteristic is set so that the vehicle speed corresponds to the load. Further, when the shift characteristic is changed to the second shift characteristic, the lock-up is performed in order to compensate for the shortage of the driving force by the torque increasing action of the torque converter and to prevent or reduce the shock caused by the switching of the lock-up clutch. (The engagement of the lock-up clutch) is not performed (the lock-up is performed at the third speed and the fourth speed in the first speed change characteristic). In addition, in the second shift characteristic, the fourth speed is not necessary because the tendency of the driving force to be insufficient is increased.
The shift is performed in the range of the third speed (in the first shift characteristic, the speed is changed in the range of all the first to fourth speeds). As will be apparent from the above description and the comparison between FIGS. 2 and 4 (the comparison between FIGS. 3 and 5), the second speed change characteristic has an enlarged low-speed range compared to the first speed change characteristic. It has become. More specifically, the second speed change characteristic is such that the low speed range region is expanded to a higher vehicle speed side in a region where the frequently used engine load is small as compared with the first speed change characteristic, In addition, it is assumed that there is no fourth speed region as the highest gear.

Overview of Shift Control An overview of shift control by the control unit 10 will be described. First, when the gradient of the traveling road is smaller than a predetermined value, the control unit 10 basically selects the first shift characteristic as the shift characteristic used for the shift control.
When the gradient of the traveling road becomes larger than a predetermined value, the second shift characteristic is selected as the shift characteristic used for the shift control. Of course, for each of the two types of shift characteristics, whether to use the power mode or the economy mode is selected by the mode selection switch 15. More specifically, as shown in FIG. 11, the second speed change characteristic is selected when the gradient becomes larger than a predetermined value Ang4 (positive) when the vehicle is going uphill, and the predetermined value is set when the gradient is downhill. ), The second speed change characteristic is selected. Ang3 is set for Ang4 (Ang3 <Ang4), and Ang2 is set for Ang1 (Ang2> Ang) in order to prevent hunting of shift characteristic switching due to a change in the gradient.
1) Yes.

Although the above is the principle, in order to switch the first shift characteristic from the second shift characteristic without a sense of incongruity to the driver, a vehicle which is frequently performed in a winding road on the premise that the gradient of the traveling road is large. The shift characteristics are switched in synchronization with the acceleration or deceleration of the vehicle. Further, when the vehicle speed is low, even when the vehicle is in the winding road, the traffic volume is relatively high and the traffic is relatively congested, or when the vehicle starts, or when the vehicle is at an intersection.
Shift control is performed according to shift characteristics (FIG. 4,
(Refer to the hatched area in FIG. 5). In order to prevent hunting in switching between the first shift characteristic and the second shift characteristic according to the vehicle speed, a hysteresis is provided for the switching vehicle speed between the two shift characteristics (FIGS. 4 and 5 show this hysteresis). Not shown).

In addition to this, once the shift to the shift characteristic based on the second shift characteristic is performed, the return to the first shift characteristic is delayed for a predetermined time (for example, several tens of seconds). It is possible to sufficiently confirm again whether or not the situation has returned to the first shift characteristic. That is, in the winding load, as shown in FIG.
Although there may be a fairly long straight line distance between the X point and the Y point, this straight line portion is only a part of the winding road and immediately follows the continuous road conditions of the original curve. It may be. Therefore, such an X
In order to prevent a situation in which the control temporarily returns to the shift control based on the first shift characteristic on the straight road between the point and the point Y and shifts again to the shift control based on the second shift characteristic in a short time, Delay time setting for reconfirmation is advantageous. Since the delay time corresponds to a relatively long straight road in the winding road, the delay time can be replaced with a travel distance (for example, several hundred meters).

Next, referring to the flowcharts shown in FIGS. 6 to 9,
The details of the shift control by the control unit 10 will be described in detail. In the following description, M, N, R or S indicates a step. The timer value t described later is counted by an interrupt process or the like using a soft timer.

First, the entire system is initialized at M1 in FIG. 6. In this initialization, the winding load flag WF is reset to 0. When the WF is "0", it means that the shift control is performed by the first shift characteristic, and when WF is "1", it means that the ascending gradient is large and the vehicle is accelerated. Further, when WF is "2", it means that the downhill gradient is large and the vehicle decelerates. Next, as will be described later, the gradient of the traveling road is detected by calculation in M2, and the shift control is subsequently performed in M3.

The gradient detection at M2 is performed based on the flowchart of FIG. In this flowchart, a predicted acceleration gP on a flat road (zero gradient) is mapped in advance and stored using the accelerator depression amount α and the vehicle speed V as parameters (set for each gear position). ), The degree of the gradient is known by comparing the predicted acceleration gP with the actual acceleration gA obtained by differentiating the vehicle speed.

Assuming the above, at N1 in FIG. 7, the current accelerator depression amount α, vehicle speed V, and gear position (gear position) G are read. After this, N2, N4,
By the determination of N6, a map storing the predicted acceleration on the flat road corresponding to the current gear position G is selected (N3,
N5, N7 or N8), and an example of this selected map is shown in FIG. After the map selection at N3, N5, N7 or N8, at N9, based on the current accelerator depression amount α and the vehicle speed V, the predicted acceleration gP on the flat road is compared with the selected map. Read. Thereafter, at N10, the actual acceleration gA of the vehicle is calculated by differentiating the vehicle speed V with the time t. Then, in N11, the gradient Ang is calculated by subtracting gA from gP (an upward gradient when Ang is positive, An
Downward slope when g is negative).

The gear change control at M3 in FIG. 6 is performed based on the flowcharts in FIGS. In FIG. 8, first, data input necessary for R1, that is, A
ng, the vehicle speed V, the accelerator pedal depression amount α, and the brake operating state are read. Thereafter, in R2, the actual acceleration (deceleration) dV / dt of the vehicle is calculated by differentiating the vehicle speed V with time t.
Is calculated.

After R2, at R3, it is determined whether or not WF is 0. Since WF is initially 0, the process shifts to R4. In this R4, it is determined whether or not the detected gradient Ang (N11 in FIG. 7) is smaller than Ang1 (see FIG. 11). When the determination in R4 is NO, in R5, the detected Ang is changed to Ang4 (see FIG. 11). 11) is determined. When the determination of R5 is NO, it means that the shift control based on the first shift characteristic should be performed. In this case, after resetting WF to 0 in R6, the timer value t of the above-described delay time (road condition confirmation time) is reset to 0.

After R7, the flow shifts to S1 in FIG. In S1, it is determined whether or not the power mode is selected by the mode switch 15. In the determination of S1, Y
In the case of ES, in S2, the first speed change characteristic for the power mode shown in FIG. 3 is selected. When the determination in S1 is NO, in S3, the first speed change characteristic for the economy mode shown in FIG.
The shift characteristic is selected.

After S2 or S3, S4, S5
, A shift-up determination and a shift-down determination are made. This determination is made by checking whether the shift speed obtained based on the selected shift characteristic is higher (shift up determination) or lower (shift down determination) than the current shift speed. Done. Thereafter, in S6, it is determined whether or not WF is 0. If the determination in S6 is YES, in S7, it is determined whether or not to lock up based on the shift characteristic selected from FIG. 3 or FIG. If NO in S6, the lock-up is not performed when the second speed change characteristic is selected.
(Cancel).

After S7 or S8, S4, S
The operating state of the solenoids 5, 6 is changed according to the result of the determination (set) in 5, S7 or S8. The R
If the determination in step S5 is YES, all the conditions that the accelerator pedal depression amount α is larger than the predetermined value and the vehicle is downshifted or dV / dt is larger than the predetermined value are satisfied by the determination processing of R12 to R14. Then, the flow shifts to R15. When the process shifts to R15, the vehicle is traveling on a large ascending slope and is accelerating. Therefore, after setting WF to 1, the process shifts to R11. In this R11, it is determined whether or not the vehicle speed V is in a speed range in which the shift control is performed based on the second shift characteristic, that is, V is V ₃
(For example, 20 km / h). When the determination in R11 is NO, the process shifts to R6 (shift control based on the first shift characteristic), and when YES, the processes after S10 in FIG. 9 are performed. This S10-S1
The processing of step 2 corresponds to the processing of steps S1 to S3, and is the same as the processing of steps S1 to S3 except that the shift characteristic to be selected is the second shift characteristic. Of course, in the case of a route through S10, the determination in S6 is NO, and the lock-up is OFF (released). Note that R12,
If the determination in R14 is NO, it is not the timing to switch to the second shift characteristic, so the routine shifts to R6 (shift control based on the first shift characteristic).

If the determination in R4 is YES, the downgradient is large, and in this case, the deceleration is determined by the determination of R8 and R9 during the brake which is the timing for switching to the second shift characteristic. When the condition of large is satisfied, WF is set to 2 at R10, and then R
11 and subsequent processes are performed. If the determinations of R8 and R9 are NO, the process shifts to R5.

If the determination in R3 is NO, the second
This is when the shift control based on the shift characteristics is being performed.
At this time, a process of continuing or stopping the shift control based on the second shift characteristic is performed by the processes of R16 to R21. That is, first, it is determined whether or not WF is 1 in R16, and YES is determined in this determination of R16.
In the case of, it is determined whether or not Ang is larger than Ang3 (see FIG. 11) at R17. If the determination in R17 is YES, it means that the vehicle has satisfied an uphill gradient for continuing the shift control based on the second shift characteristic. In this case, the process shifts to R19 and the vehicle speed V becomes the second speed. It is determined whether or not the speed is higher than a set vehicle speed V _{4 at which the} speed change control based on the speed change characteristics should be stopped (for example, V ₄ <V ₃ at 15 km / h). If the determination in R19 is YES, the count value t of the timer is reset to 0 in R20, and the routine shifts to FIG. 9 (continuation of the shift control based on the second shift characteristic).
When the determination in R19 is NO, the process shifts to R6 (switching to the shift control based on the first actual shift characteristic).

When the determination in R17 is NO,
This is when the ascending slope becomes smaller. In this case, R1
In 8, whether or not a predetermined time t ₁ has passed since the upward gradient is reduced is determined, N is judged at this R18
In the case of O, the process proceeds to S10 of FIG. 9 (continuation of the shift control based on the second shift characteristic). Also, YES in the determination of R18.
In the case of, the routine proceeds to R4, and it is determined again whether or not the gradient is large enough to perform the shift control based on the second shift characteristic again.

If the determination in R16 is NO, R21
To whether the descending gradient is small, that is, Ang
Is smaller than Ang2 (see FIG. 11). When the determination in R21 is YES, the process shifts to R19, and when the determination is NO, the process shifts to R18.

Although the embodiment has been described above, the engine load as a parameter for setting the basic shift characteristic (first shift characteristic) includes, in addition to the accelerator depression amount, the throttle opening, the intake air amount, the fuel injection amount, and the like. The vehicle speed as a parameter for setting the shift characteristics includes the rotation speed of the driven wheels, the rotation speed of the transmission output shaft, and the speed of the torque converter 3. Appropriate ones such as a turbine rotation speed (a gear ratio is also taken into consideration) can be used. In addition, a sensor such as an inclinometer can be separately used for detecting the gradient of the traveling road, but it is more cost-effective to calculate the gradient by calculation as in the embodiment.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention.

FIG. 2 is a shift characteristic diagram showing a first shift characteristic and an example of an economy mode.

FIG. 3 is a shift characteristic diagram showing an example of a first shift characteristic and a power mode.

FIG. 4 is a shift characteristic diagram showing an example of an economy mode with a second shift characteristic.

FIG. 5 is a shift characteristic diagram showing an example of a power mode in a second shift characteristic.

FIG. 6 is a flowchart showing a control example of the present invention.

FIG. 7 is a flowchart showing a control example of the present invention.

FIG. 8 is a flowchart showing a control example of the present invention.

FIG. 9 is a flowchart showing a control example of the present invention.

FIG. 10 is a diagram showing a map used for calculating a gradient of a traveling road by calculation.

FIG. 11 is a diagram showing the magnitude of a gradient when selection switching between a first speed change characteristic and a second speed change characteristic is performed.

FIG. 12 is a simplified plan view showing an example of a winding load.

[Explanation of symbols]

 1: Engine 2: Automatic transmission 3: Torque converter 4: Transmission mechanism 5: Lock-up solenoid 6: Transmission solenoid 10: Control unit 11: Sensor (accelerator depression amount) 12: Sensor (vehicle speed) 13: Sensor ( Brake)

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[Procedure amendment]

[Submission Date] October 6, 1999 (1999.10.
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Continuing on the front page (72) Inventor Kazutoshi Nobumoto 3-1, Fuchu-cho Shinchi, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Toshihiro Matsuoka 3-1, Fuchi-cho Shinchi, Aki-gun Hiroshima Pref. 72) Inventor Toshiaki Tsuyama 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (1)

Claims (1) A torque converter with a lock-up clutch is provided, and lock-up control means for controlling engagement and disengagement of the lock-up clutch based on a preset lock-up characteristic is provided. A control device for the automatic transmission, comprising: a gradient detecting means for detecting a value relating to a gradient of a traveling road; and receiving the output from the gradient detecting means, wherein when the traveling road is detected to be uphill, the lock-up control is performed. And a prohibiting means for prohibiting engagement of the lock-up clutch prior to the means. (2) In claim 1, further comprising: a downshift detecting means for detecting a downshift, wherein the prohibiting means is provided on condition that the downshift is detected by the downshift detecting means. A control device for an automatic transmission, wherein the control device is set to prohibit engagement of an up clutch.