JPH0510438A - Speed change controller for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent the generation of a slip by performing stage-by-stage sequential speed change forbidding skip speed change to a low speed stage at the time of lateral acceleration being over the reference value. CONSTITUTION:The output of a lateral G sensor 14, a vehicle speed sensor 11, an engine speed sensor 12, a throttle opening sensor 13 and a gear position sensor 16 is inputted into a microcomputer 10. An actuator 24 is controlled by the output of a select lever position sensor 15. When the lateral G detected by the lateral G sensor 14 is larger than the reference value at the time of a select lever being operated into the low speed stage direction, a driving circuit is controlled in such a way as to perform stage-by-stage sequential speed change forbidding skip speed change.

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 when a select lever is operated to exert an engine braking effect.

[0002]

2. Description of the Related Art In a vehicle, as a main brake on a long downhill or as an auxiliary to a foot brake on a flat road, the transmission gear is switched to a lower gear to drive an engine having inertial force from the wheel side. In so-called engine braking, a braking force generated by a negative driving force is generated. This is executed by operating the select lever when the automatic transmission is installed.

When the automatic transmission has, for example, four forward gears, when the select lever is operated to the second range while the vehicle is traveling at the fourth speed in the D range, the automatic transmission is switched from the fourth speed to the second speed. Braking force is applied to the drive wheels by the engine that tries to rotate at a low speed when the accelerator pedal is released.

[0004]

However, in the conventional automatic transmission, the gear position can be switched by directly reflecting the operation of the select lever to the 2 range or the L range by the driver, so that the vehicle is driven by the driver depending on the running condition. There may be cases where the unintended behavior of is displayed. In particular, when a so-called jump shift is performed in which the shift speed is skipped by 1 or more and switched by 2 or more when the select lever is operated while traveling at a high speed on a curved road, the change in the braking force applied to the drive wheels is changed. Is too large to lose grip with the road surface and slip, resulting in excessive vehicle behavior.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a gear shift control device capable of obtaining a sufficient braking force by switching gear stages without causing a slip when the select lever is operated to obtain an engine braking effect. And

[0006]

Therefore, according to the present invention, as shown in FIG. 1, a shift control device for an automatic transmission having a shift means 1 for shifting to a target shift speed selected based on the operation of a select lever. At 3, the lateral acceleration detecting means 2 for detecting the lateral acceleration acting on the vehicle, and the means 3 for detecting that the shift from the current gear stage to the target gear stage selected by the select lever is an interlaced gear shift to the low gear stage Further, when the lateral acceleration is equal to or more than a reference value, the interlaced shift is prohibited, and the interlaced shift is prohibited, and the shift mode control means 4 for sequentially shifting the shift is provided.

[0007]

When the select lever is operated from the high-speed range to the low-speed range, if a predetermined lateral acceleration acts on the vehicle, the final shift speed selected by the select lever is shifted by two or more gears. Even in the case of gears, the speed is changed step by step.

[0008]

FIG. 2 shows an embodiment of a shift control device to which the present invention is applied. The microcomputer 10 is provided with an actuator 24 as a transmission means for controlling the operation of a clutch, a brake or the like for switching the combination or connection of transmission elements such as gears. The microcomputer 10 includes a vehicle speed sensor 11, an engine rotation sensor 12, a throttle opening sensor 13, a lateral G sensor 14, and a select lever position sensor 15 via a sensor input circuit 20.
And the signal from the gear position sensor 16 is input. The gear position sensor 16 emits a signal indicating the currently operated gear stage. The microcomputer 10 calculates based on these input information, and controls the actuator 24 of the shifting means through the drive circuit 22.

Regarding the engine brake, the microcomputer 10 monitors the select position from the select lever position sensor 15, the current gear position from the gear position sensor 16 and the lateral acceleration from the lateral G sensor 14, and the select lever is in the low speed position. When operated in the range direction,
When a predetermined lateral acceleration set in advance as a reference value is occurring, the shift mode is switched to shift gears one step at a time to a lower speed.

The control flow is shown in FIG. 3. First, in step 20 of the main control routine, the current vehicle speed of the traveling vehicle, the engine speed, the throttle opening and other signals from each sensor are fetched. In step 21, it is checked whether or not the select lever has been operated, and if it has been operated, the subroutine starting from step 22 is entered. If the select lever is not operated and the range is not changed, the optimum shift speed for the running state of the vehicle obtained from each sensor signal within the range is determined and executed on the main routine based on the shift map.

In step 22, the direction in which the select lever is operated is checked. If the operation is in the direction of the high speed stage, such as from the N range or the L range to the D range, the process proceeds to step 26, which is the conventional conventional shift mode control, and within the selected range, the engine speed, The gear is switched to a predetermined gear according to the load calculated from the throttle opening.

On the other hand, when the select lever is operated toward the low speed stage, the routine proceeds to step 23, where the lateral G (acceleration) received by the vehicle is read and it is judged whether the lateral G is larger than a reference value. This reference value is determined from the viewpoint of whether or not the drivability is adversely affected when an interlaced shift is performed with the lateral G acting.

When the lateral G is larger than the reference value, the routine proceeds to step 24, and whether the shift from the current gear to the gear of the range selected by the select lever corresponds to an interlaced gear skipping an intermediate gear. Check. Then, when the jump shift is applied, for example, when the shift down from the fifth speed to the third speed is performed, the process proceeds to step 25, the jump shift is prohibited, and the target shift speed selected by the select lever is set to 5 The control shifts to the slow shift mode in which the gears are sequentially shifted from the fourth speed to the fourth speed and from the fourth speed to the third speed one gear at a time.

When it is determined in step 23 that the lateral G is small, interlaced gear shifting does not cause a problem in drivability, so the routine proceeds to step 26, in which the gear range of the range selected by the select lever is selected in accordance with the normal gear shift mode. Switch to. Further, even when the jump shift is not applied in step 24, the shift is switched in the normal shift mode of step 26.

Step 24 constitutes an interlaced shift detecting means, and steps 22 to 25 and 26 constitute a shift mode controlling means.

Here, in order to detect the lateral G, an acceleration sensor provided independently can be used. For example, a map using the steering angle of the steering wheel and the vehicle speed as parameters is prepared and checked in step 23. It may be read out again.

[0017]

As described above, according to the present invention, when a select operation is performed to a low speed range that results in an interlaced shift when the lateral G is large, the interlaced shift is prohibited and the target shift stages are sequentially shifted one by one. Therefore, even if the engine is braked by operating the select lever while the vehicle is turning, the wheels do not lose their grip with the road surface and good drivability is ensured. Moreover, since the gear is surely shifted to the low-speed gear stage of the finally selected range, it is possible to sufficiently obtain the engine braking effect of the level intended by the driver.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing an example.

FIG. 3 is a diagram showing a control flow.

[Explanation of symbols]

1 speed change means 2 Lateral acceleration detection means 3 Interlaced shift detection means 4 Shift mode control means 10 Microcomputer 11 Vehicle speed sensor 12 Engine speed sensor 13 Throttle opening sensor 14 Horizontal G sensor 15 Select lever position sensor 16 Gear position sensor 20 Sensors input circuit 22 Drive circuit 24 actuators

Claims (2)

[Claims] 1. A shift control device for an automatic transmission having a shift means for shifting to a target shift speed selected based on an operation of a select lever, a lateral acceleration detecting means for detecting a lateral acceleration acting on a vehicle, A means for detecting that the shift from the current shift stage to the target shift stage selected by the select lever is an interlaced shift to a low speed stage; and when the lateral acceleration is equal to or higher than a reference value, the interleaved shift is performed. A shift control device for an automatic transmission, comprising: a shift mode control means for prohibiting interlaced shifts and shifting in steps one by one. 2. The shift control device for an automatic transmission according to claim 1, wherein the reference value of the first-half lateral acceleration changes according to the vehicle speed.