JPH039166A - Speed change control device of automatic transmission - Google Patents

Abstract

PURPOSE:To improve the effectiveness of an engine brake so as to obtain stable performance of downhill running by providing a speed change control means which selects a downhill-time speed change pattern, set to a shift position lower than normal, when a downhill running condition is detected. CONSTITUTION:In a control unit 8, an idle switch 3A is connected to an additionally provided throttle sensor 3, engine speed sensor 4 and water temperature sensor 5, when a downhill running condition is detected being based on a signal from each sensor, a downhill-time speed change pattern is selected, and by judging a speed change point in an automatic transmission 1 to control valve- open duty of each solenoid valve 2A to 2E, a speed change control is performed. In the downtimespeed change pattern, a shift position is set so that an engine brake is effective in the range of a speed N not excessive for the engine speed N. That is, even in a high speed region of the engine speed N, a shift position is set to to 3rd-speed effectively apply the engine brake, and in a low speed region, the shift position is set sufficiently low to apply the engine brake as effective as possible, thus downhill running performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a device for controlling the speed change of an automatic transmission, and particularly relates to speed change control during downhill travel.

<Prior Art> Conventionally, vehicles equipped with an automatic transmission with a torque converter are known to shift gears according to a preset shift pattern based on vehicle speed and throttle valve opening. (Refer to Japanese Utility Model Application Publication No. 194231/1983, etc.).

<Problems to be Solved by the Invention> However, the shift pattern is determined based on the vehicle speed and throttle valve opening based on flat road surface driving, so when driving downhill, even though the throttle opening is small, As the vehicle speed increases, if the shift pattern based on the flat road driving standard is followed, a high shift position (such as 4th gear) is used, resulting in the problem that engine braking is difficult to apply.

The present invention has been made in view of these conventional problems, and an object of the present invention is to provide a shift control device for an automatic transmission that solves the above problems by using a shift pattern exclusively for descending slopes. do.

<Means for Solving the Problems> Therefore, as shown in FIG. The present invention includes a shift control means that selects a shift pattern for descending slopes to set the shift position of the automatic transmission to a lower shift position than normal when a hill running condition is detected, and performs shift control.

<Operation> The downhill detecting means detects the downhill running state based on the frequency of deceleration driving, the vehicle speed during deceleration, the rate of change in vehicle speed, and the like.

When the downhill running state is detected, the shift control means selects a downhill shift pattern that sets the shift position lower than the shift position of the shift control that is normally performed when running on a flat road, and performs shift control. This increases the effectiveness of engine braking and provides stable downhill driving performance.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1 showing the configuration of one embodiment, there is shown a transmission unit 1 consisting of a torque converter and a transmission. In order to control the hydraulic pressure of the transmission elements, solenoid valves 28 to 2E are provided which are interposed in the hydraulic pressure passages leading to these and which control the hydraulic pressure by controlling the valve opening duty.

On the other hand, there is a throttle sensor 3 equipped with an idle switch 3A that detects the opening of a throttle valve installed in the intake passage of an engine (not shown) and is turned on when the engine is idle below a predetermined opening. A rotation speed sensor 4 that is installed or built into the distributor and detects the engine rotation speed N, and the engine cooling water temperature T. A water temperature sensor 5 is provided to detect the water temperature. Further, a vehicle speed sensor 6 for detecting a vehicle speed (2) is provided near the output shaft of the transmission, and a shift position sensor 7 for detecting a shift position G (shift position) is provided in the transmission.

Each signal detected by these is input to the control unit 8.

The control unit 8 is configured with a built-in microcomputer, and based on the signals from each sensor,
A downhill running state is detected, and when a downhill running state is detected, a shift pattern for downhill is selected, a shift point of the transmission is determined based on the shift pattern, and each of the solenoid valves 2A is Shift control is performed by controlling the valve opening duty of ~2E.

FIG. 3 shows a downhill running state detection routine.

This routine constitutes a downhill detecting means.

In step (denoted as S in the diagram) ■, the current engine speed N and the idle switch ON/OFF.

Read the detected value of vehicle speed■.

In step 2, it is determined whether the idle switch 3A is ON and the engine speed N is greater than or equal to the lower limit rotation speed N0 set for the water temperature T8.

This determination condition is a deceleration condition under which fuel cut is normally performed and a road gap condition.

If the above determination is YES, the process proceeds to step 3, where the counter C is counted up, and then the process proceeds to step 4. If the determination is NO, the process directly proceeds to step 4.

In step 4, the idle switch 3A is turned on and the vehicle speed ■ is set to a predetermined value ■ higher than the vehicle speed during coasting. (for example, 20 to 30 km/h). This condition (condition for YES) is
Since the vehicle is traveling downhill, the conditions are such that if a normal speed change pattern for traveling on a flat road is used, the vehicle will be controlled to 4th gear.

If the above determination is YES, the process proceeds to step 5, where the counter C is counted up, and then the process proceeds to step 6. If the above determination is NO, the process directly proceeds to step 6.

In step 6, the idle switch 3A is ON, and the rate of change ΔV of the vehicle speed ■ is a predetermined value Δ■. Determine whether the value is greater than or not. This is a condition where when driving downhill in traffic jams, the vehicle accelerates simply by releasing the accelerator pedal, and is controlled only by the brakes.

If the above determination is YES, the process proceeds to step 7, where the counter C is counted up, and then the process proceeds to step 8. If the determination is NO, the process directly proceeds to step 8.

In step 8, the count integrated value of counter C in a predetermined time interval (for example, 3 minutes), that is, step 2.4
．． The time ratio TDEC for which condition 6 is satisfied is determined. This is obtained by subtracting the count value before the predetermined time from the latest count value.

In step 9, the time ratio TDEC is set to a predetermined value T D
Compared with E Co, when TDEC>TDEC,
When it is determined that the vehicle is in a downhill running state, the process proceeds to step 10, and the determination flag F_DEC is set to 1. Otherwise, the process proceeds to step 11, and the determination flag F_DEC is reset to 0.

Next, the shift control in the D range by the control unit 8 will be explained according to the flowchart shown in FIG.

In step 21, the detected values of the current engine speed N, throttle valve opening θ, and vehicle speed V are read.

In step 22, a downhill running state determination flag F is set.

Determine whether or not is 1.

If the determination in step 22 is NO, when the vehicle is not traveling downhill, the process proceeds to step 23, where a map of a conventional shift pattern for traveling on flat roads is referred to in accordance with the vehicle speed ■ and the throttle valve opening θ. Find the corresponding target shift position.

Then, the process proceeds to step 25, where the target shift position Wsv
The solenoid pulps 2A to 2E are controlled to perform speed change control.

On the other hand, when the determination in step 22 is YES, that is, it is determined that the driving state is downhill, the process proceeds to step 24, and a map of the speed change pattern set for downhill driving according to the engine speed N is referred to, and the corresponding target Search for shift position SP.

Then, the process proceeds to step 25, where the target shift position S,
The solenoid pulps 2A to 2E are controlled to perform speed change control.

Here, in the shift pattern for descending slopes, the shift position is set so that the engine brake is effectively applied to the engine rotational speed N within a range where N does not become excessive. That is, even in the high range of the engine speed N, the engine brake is set to 3rd gear to apply the engine brake, and in the low range, the shift position is set sufficiently low to maximize the engine brake while suppressing engine stalling. Therefore, without being fixed to 4th gear as in the past, engine braking can be applied as much as possible to improve the downhill running performance of a vehicle equipped with an automatic transmission.

Note that the functions of steps 22, 24, and 25 constitute a speed change control means.

<Effects of the Invention> As explained above, according to the present invention, the downhill driving condition is detected and the downhill gear shift control is performed to control the shift position to a lower position than normal. The effectiveness is increased, and the downhill driving performance of vehicles equipped with automatic transmissions can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
A diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing a downhill running state detection routine of the above embodiment,
FIG. 4 is a flowchart showing the speed change control routine of the above embodiment. 1... Automatic transmission 2A-2E... Solenoid pulp 3... Throttle sensor 3A... Idle switch 4... Rotation speed sensor 5... Vehicle speed sensor 8... Control unit sensor

Claims (1)

[Claims] In the shift control device of the automatic transmission installed in the vehicle,
A downhill detecting means detects a downhill running state, and when the downhill running state is detected, a downhill shift pattern is selected to set the shift position of the automatic transmission to a lower shift position than normal, and the gear shift is controlled. 1. A speed change control device for an automatic transmission, comprising a speed change control means.