JPH03282051A - Shift control device for automatic transmission - Google Patents

Abstract

PURPOSE:To render an engine brake effective when occasion demands by controlling shift according to a shift schedule for engine brake when a throttle opening is returned from a throttle opening area higher than a set value toward zero at a rate of change higher than the reference rate of change of a throttle opening. CONSTITUTION:A transmission control unit 5 selects a rapid deceleration shift schedule for an engine brake when a throttle opening TVO is returned from a throttle opening area higher than a preset value CTVO toward zero at a rate of change VTVO of a throttle opening higher than a preset reference rate of change CVTVO of a throttle opening. The transmission control unit effects control to positively render an engine brake effective by effecting shift down of one range. Namely, when the driver of a vehicle demands an engine brake, even when a shift up signal is not outputted, positive shift down is effected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shift control device for an automatic transmission that automatically controls gear change based on a shift schedule.

(Prior Art) Generally, an automatic transmission is constructed by combining a torque converter consisting of a pump impeller, a turbine runner, a stator, etc., and a multi-stage gear type transmission mechanism connected to the turbine runner of the torque converter. Things are commonly used.

Traditionally, this type of automatic transmission has been equipped with a hydraulic control device whose main component is a hydraulic circuit, and
It is well known that a shift condition is determined based on a shift schedule stored in advance in a storage device, and a hydraulic control device performs a shift according to the determined shift condition.

By the way, one of the drawbacks of the above conventional automatic transmission is that
For example, when engine braking is required, an upshift is performed against the will of the driver of a vehicle equipped with this automatic transmission.

For example, when accelerating to the front of a corner, decelerating suddenly at the corner, and cornering, the gear position changes during the acceleration to the second gear in the shift schedule, as shown by points P and P in Figure 7. Even if the vehicle is in this range, when the driver takes his or her foot off the accelerator pedal to apply engine braking to decelerate for cornering, the vehicle will shift to 4th gear and the engine brake will no longer work against the driver's will. There was a drawback.

In order to eliminate these shortcomings, the shift schedule was configured so that the one speed range of the automatic gear shift when the throttle opening is close to fully closed extends to a range one speed higher than the above speed range until a predetermined vehicle speed is reached. Some methods have been proposed (for example, see Japanese Patent Publication No. 52-20630).

In this model, the automatic transmission speed range where the throttle opening is close to fully closed extends to the one-speed high speed range, so
When off-throttle, it automatically gears down to the next speed range. Thereby, the engine brake acts effectively, and deceleration by the engine brake can be achieved.

(Problem to be Solved by the Invention) By the way, in the above-mentioned device, when the throttle is off, the gear is automatically lowered to the lower speed range, so for example, the accelerator pedal is slowly returned from well before the target stop position to decelerate. In this case, when the amount of depression of the accelerator pedal becomes small and the throttle opening becomes close to zero, a gear down suddenly occurs, and there is a problem in that smooth deceleration cannot be achieved.

An object of the present invention is to provide a shift control device for an automatic transmission that can apply engine braking when necessary in response to the will of a vehicle driver.

(Means for Solving the Problems) For this reason, the present invention provides a shift control device for an automatic transmission in which gears are switched based on a shift schedule. It has multiple shift schedules, including a shift schedule for engine braking, which is set when the gear shift line shifts to a high vehicle speed side, and the throttle opening is preset from a throttle opening range larger than a preset value. Shift control means for controlling the automatic transmission to shift according to the engine brake shift schedule when the throttle opening is returned toward zero at a throttle opening change rate greater than a reference throttle opening change rate. It is characterized by

(Function) When the vehicle driver operates the accelerator pedal to apply engine braking, the throttle opening changes from a throttle opening range larger than a preset value to a preset standard throttle opening. The throttle opening is returned toward zero at a rate of change in the throttle opening that is greater than the rate of change.

When the shift control means detects such a change in the throttle position and throttle movement, it switches the shift schedule to a shift schedule for engine braking and controls the automatic transmission to shift.

(Effects of the Invention) According to the present invention, it is determined from the position and movement of the throttle that the driver of the vehicle requests engine braking, and the automatic transmission is controlled to shift according to the shift schedule for engine braking. When engine braking is required, engine braking is applied in response to the driver's will, and gear change control can be performed in response to the driver's request for engine braking.

(Example) Below, the present invention will be described in detail with reference to the accompanying drawings.

Overall Configuration The overall configuration of a shift control device for an automatic transmission according to the present invention is shown in FIG.

In FIG. 1, an engine 1 has an automatic transmission 2, and its output is transmitted to drive wheels of a vehicle (not shown) via the automatic transmission 2.

The automatic transmission 2 includes a torque converter 3 and a multi-speed transmission mechanism 4, which has four forward speeds and one reverse speed in this embodiment. Ru. Then, the multi-stage transmission mechanism 4 changes the combination of excitation and demagnetization for the plurality of transmission solenoids 7 and lock-up solenoids 8 of the hydraulic control circuit 6 in response to a switching command signal from the transmission control unit 5, thereby automatically shifting the gears. Switches the operating mode of the hydraulic actuator for gear shifting or lock-up of machine 2. As a result, the gear position is changed and the lock-up clutch is turned on and off.

The transmission control unit 5 receives a throttle opening signal TVO from a throttle opening sensor 12 that detects the throttle opening TVO of a throttle valve 11 installed in the intake passage 9 of the engine 1, and also receives an automatic transmission control unit 5. A turbine rotation speed signal is manually input from the turbine rotation speed sensor 13 of the torque converter 3 of the machine 2 as a vehicle speed signal.

The transmission control unit 5 includes a CPU and a ROM.

It is composed of a microcomputer including a RAM, CLOCK (soft timer), and input/output interface circuits such as an A/D converter and a D/A converter.

When the automatic transmission 2 is controlled according to control example 1, which will be explained later, the automatic transmission 2 is controlled by a rapid deceleration routine for engine braking executed by the CPU according to the flowchart of FIG. A control program is written into the ROM. And the above ROM
The rapid deceleration shift schedule for engine braking shown in FIG. 3 and the normal shift schedule explained in FIG. 7 are also written.

On the other hand, when the shift control of the automatic transmission 2 is performed according to control example 2 to be described later, the automatic transmission includes a rapid deceleration routine for engine braking performed by the flowchart of FIG. 5 executed by the CPU. A control program is written into the ROM. And the above R
The rapid deceleration shift schedule for engine braking shown in FIG. 6 and the normal shift schedule explained in FIG. 7 are also written in the OM.

In the shift schedule shown in Figure 3, the shift line (2→3) for upshifting from 2nd to 3rd gear is such that the vehicle speed changes from near zero throttle opening TVO to zero throttle opening TVO. 60 on the high speed side from 25km/h
Km/h has been set.

In addition, the shift line for upshifting from 3rd to 4th gear (3
→4) is the vehicle speed in the throttle opening range from around zero throttle opening TVO to zero throttle opening TVO.
Km/h is set at a higher speed of 80 Km/h.

Furthermore, the shift line for downshifting from 4th to 3rd gear (
4→3) is when the vehicle speed is 3 in the throttle opening range from near zero throttle opening TVO to zero throttle opening TVO.
The speed is set to shift from 0 km/h to the high speed side of 76 km/h.

Furthermore, the shift line (3 → 4) for downshifting from 3rd gear to 2nd gear changes from near zero throttle opening TVO to throttle opening range where throttle opening TVO is zero, and the vehicle speed is 11 km/h. The speed has been set to shift from 56 km/h to the high speed side.

On the other hand, in the shift schedule shown in Fig. 6, the shift line for upshifting from 2nd to 3rd gear (2→3) and the shift line for shifting up from 3rd to 4th gear (3→4) are based on the throttle opening. Throttle opening TV from around zero TVO
The vehicle speed in the throttle opening range where O is zero is set to shift to the high speed side, similar to the shift schedule in Figure 4, whereas the shift line for downshifting from 4th to 3rd gear (4 →3) and the shift line (3→4) for downshifting from 3rd gear to 2nd gear are set in the same way as the shift schedule in FIG.

Note that in FIGS. 3, 6, and 7, L/U is a lock-up line indicating a region where the lock-up clutch of the torque converter 3 is engaged.

The CPU of the transmission control unit 5 receives the throttle opening signal TVO supplied from the throttle opening sensor 12 and also receives the turbine rotational speed of the torque converter 3 as a vehicle speed signal, and selects a shift schedule.

Outline of shift control of automatic transmission When the driver of a vehicle performs an accelerator operation to apply engine braking, the throttle opening TvO changes as shown, for example, by curve m in FIG. 4, and at time 1.
From time [! or the period from time t to time t4, from a throttle opening range where the throttle opening TVO is larger than the preset value CTVO, the throttle opening is larger than the preset standard throttle opening change rate CVtvo. The throttle opening T is the opening change rate VTVO.
VO is returned toward zero.

On the other hand, when the driver of the vehicle is operating the accelerator pedal normally, the throttle opening TVO changes gradually as shown by curve m in FIG. As in the period from t1 to time t, or from time t to time t4, the throttle opening degree TV
There is no period in which O suddenly decreases.

Control by the shift control device of the automatic transmission having the above-mentioned overall configuration consists of three stages of control: stage A, stage B, and stage C.

Stage A In stage A, in the curve m of FIG. 4 described above, the period from time t1 to time t or from time [3 to time
The state of change in the throttle opening degree T■0 shown in the period of is detected, and based on this, it is determined whether or not the driver of the vehicle requests engine braking.

Step B If it is determined in step A that the driver requests engine braking, a rapid deceleration shift schedule for engine braking is selected to control the automatic transmission.

Stage C Cancels the shift schedule for engine braking.

Next, two control examples 1 and 2, which are comprised of the above steps A, B, and C, will be explained.

Control example 1 In this control example 1, the throttle opening TVO is from a throttle opening range larger than a preset value CTVO,
Preset reference slot/nottle opening degree change rate c v'
When the throttle opening TVO returns toward zero at a throttle opening change rate VTVO that is greater than rvo, select the rapid deceleration shift schedule for engine braking shown in Figure 3 and downshift by one step. control to actively apply engine braking.

Next, this control example 1 will be explained with reference to the flowchart of FIG. 2.

When the control flow shown in FIG. 2 starts, first, in step S1, the return speed VTVO of the throttle opening TVO is
is the preset standard throttle opening change rate CVTv
It is determined whether or not it is greater than or equal to o.

In step S1 above, the throttle opening return speed v
If it is determined that 'rvo is equal to or greater than the preset reference throttle opening change rate CV TVO, step S2
Proceed to execution. In this step S2, it is determined whether the throttle opening degree TVO 11 seconds before the start of returning the throttle opening degree was equal to or greater than the reference throttle distance CTVO set for determining engine braking.

If it is determined in step S2 that the throttle opening &TVO is equal to or greater than the reference throttle opening degree CTVO, the process proceeds to step S3, where it is determined whether or not there is a shift signal.

Therefore, when the driver of the vehicle requests engine braking and the throttle opening degree TVO changes from time t2 to t or from time t4 to time t4 in FIG. It is determined that the opening return speed V TVO is equal to or higher than the preset reference throttle opening change rate CV TVO, and the process proceeds to step S2.
At , it is determined that the throttle opening degree TVO 11 seconds before the start of returning the throttle opening degree was greater than or equal to the reference throttle opening degree CTVO set for determining engine braking.

On the other hand, if it is determined in step S1 that the throttle opening return speed VTVO is less than the preset standard throttle-to-throttle degree change rate CTVO,
If it is determined in step S2 that the throttle opening degree TVO two seconds before T2 is less than the reference throttle opening degree CTVO set for determining engine braking, step S14 is executed and a normal shift is performed. Shift control is performed according to the schedule.

Engine braking is requested, step Sl.

When proceeding from step S2 to step S3, the gear position is determined based on the currently selected normal shift schedule shown in FIG. 7, and if no shift up signal is output, step S8 is executed. For engine braking, the rapid deceleration shift schedule of FIG. 4 is selected. As a result, in step S9, a one-stage downshift is performed, and engine braking is applied. That is, in control example 1, if the driver of the vehicle requests engine braking, a downshift is actively performed even if no upshift signal is output.

Thereafter, in step SIO, it is determined again whether or not the accelerator pedal is depressed, and a loop of steps S8 to S9 and step SIO is executed until the accelerator pedal is depressed again.

As a result, the effect of the engine brake continues from the time the engine brake starts to act until the accelerator pedal is depressed again.

Then, in step SIO, if it is determined that the accelerator pedal has been depressed again, steps Sll and S
12. Step S13 is executed, and after a certain period of time set by timer C has elapsed, the process returns to step S1. This Timer C is used because if an upshift occurs as soon as the accelerator pedal is pressed again while engine braking is applied, the driving feeling will be impaired.
This is to cancel the sudden deceleration shift schedule after a certain period of time has passed after the accelerator pedal is depressed.

On the other hand, the driver of the vehicle requests engine braking, and in step Sl, the throttle opening is returned to a speed V. vo is determined to be equal to or greater than a preset reference throttle opening change rate CV TVO, and in step S2, the engine brake is determined based on the throttle opening TVO T1 seconds before the start of returning the throttle opening. If it is determined that the throttle opening is equal to or higher than the reference throttle opening CTVO set in , and it is determined in step S3 that there is a shift-up signal, the timer T is set in step S4, and then steps S5 to S7 loop is executed.

While executing the loop from step S5 to step S7, if the throttle opening degree TVO does not become zero and the shift up signal continues beyond the set time T of the timer T set in step S4, the shift Step S14 is executed assuming that an upshift is requested, and shift control is performed according to the normal shift schedule.

On the other hand, when the throttle is released within the time T set by the timer T,
VO is a kiln, etc. Step 9, step 81 to step S13
is executed repeatedly, speed change control is performed according to the rapid deceleration schedule, and engine braking is applied.

When it is determined in step S3 that the shift up signal has been output, the timer T starts the shift when step S8 is executed and the sudden deceleration schedule is selected, as can be seen from the shift schedule in FIG. This is to prevent you from downshifting immediately after shifting up.

In this way, when engine braking is required, the shift schedule shown in FIG. 4 for engine braking is selected from the shift schedule shown in FIG. 7 in response to the driver's will, and the gear is downshifted. It will be done. As a result, shift control is performed in response to the driver's request for engine braking.

Control example 2 Next, a flowchart of control example 2 is shown in FIG.

-m%lbml 91+ whistle 9M/h6 cabinet mail
+ +j Pine 1. s1 When the driver of the vehicle requests engine braking, the gear position is determined based on the shift schedule call in FIG. 7 selected at that time, and it is determined in step S3 that there is no upshift signal. Then, step S14 is executed without executing step S8, and shift control is performed according to the normal shift schedule.

In this control example 2, it is determined in step S3 that there is a shift up signal, and after executing steps S4 to S7, the rapid deceleration shift schedule shown in FIG. 6 is selected in step S8 to prevent shift ab. , performs control to apply engine braking.

The flowchart in FIG. 5 is otherwise similar to the flowchart in FIG. 2, so steps corresponding to those in the flowchart in FIG. 2 are indicated with corresponding step numbers, and duplicate explanations are omitted. do.

In this control example 2, when the throttle opening degree TVO is returned toward zero and there is no output of the shift up signal, the normal shift schedule shown in FIG. 7 is selected,
When the shift up signal is output, the shift schedule shown in FIG. 6 is selected and the gear stage is prevented from shifting up.

As a result, when the driver requests engine braking, the automatic transmission 2 is prevented from shifting up, and gear change control is performed in accordance with the driver's request.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the overall configuration of an embodiment of a shift control device for an automatic transmission according to the present invention, and FIG. 2 is a flowchart of a control example of the shift control device for an automatic transmission shown in FIG. Fig. 3 is an explanatory diagram of the sudden deceleration shift schedule selected in control example 1, Fig. 4 is an explanatory diagram of changes in throttle opening when engine braking is requested and when engine braking is not required, and Fig. 5 is an explanatory diagram of the change in throttle opening when engine braking is requested and when engine braking is not requested. Control example 2 of the automatic transmission shift control device shown in Figure 1
FIG. 6 is an explanatory diagram of the rapid deceleration shift schedule selected in control example 2, and FIG. 7 is an explanatory diagram of the normal shift schedule. 1...engine, 2...automatic transmission. 3... Torque converter 4... Multi-stage transmission mechanism, 5... Transmission control unit. 6... Hydraulic control circuit, 7... Speed change solenoid. 11... Throttle valve. 12...Throttle opening sensor. 13... Turbine rotation speed sensor.

Claims (1)

[Claims] (1) In a shift control device for an automatic transmission that switches gears based on a shift schedule, the shift line is set to shift to the high vehicle speed side when the engine throttle opening is below a predetermined value. It has multiple shift schedules including a shift schedule for engine braking, and the throttle opening changes from a throttle opening range larger than a preset value to a throttle opening change rate larger than a preset reference throttle opening change rate. 1. A shift control device for an automatic transmission, comprising a shift control means for controlling the shift of the automatic transmission according to the shift schedule for engine braking when the throttle opening is returned toward zero at a certain speed.