JPH06135263A - Control device for automatic transmission and engine - Google Patents

Abstract

PURPOSE:To initiate the reduction of engine torque during power-on down-shift with optimum timing without using a rotational speed for a turbine. CONSTITUTION:The control of reduction of engine torque after the following condition is established: Ne>=NoXI-N2... (1) where Ne is the rotational speed of an engine, No is the rotational speed of the output shaft of an automatic transmission, I is a the gear ratio after down-shift, and N2 is a predetermined value. The larger the rate of variation in engine load, the larger N2, and vice versa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the engine torque during power-on downshift (during downshift in the state where power is transmitted from the engine side to the wheel side) to reduce the shock at the end of gear shift. The present invention relates to an automatic transmission and an engine control device configured to reduce the engine.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made for a technique for reducing engine torque during gear shifting to reduce gear shift shock.

Among these, in order to reduce the shock associated with the synchronization of the one-way clutch (from the idling state to the engaged state) at the end of the power-on downshift, the engine torque is reduced near the end timing of the downshift. Techniques for doing so have also been proposed (for example, JP-A-56)
No. 35857).

According to this publication, the timing of starting the reduction of the engine torque (immediately before the end of the downshift) satisfies the condition of the expression (2) from the engine rotation speed Ne and the output shaft rotation speed No of the automatic transmission. Has been proposed, and a method of starting reduction of the engine torque from now on is proposed.

Ne ≥ No x I-N1 (2)

Here, I is the gear ratio of the automatic transmission after downshifting, and N1 is a predetermined value depending on the engine load. Specifically, the difference (slip amount) between the engine rotational speed and the turbine rotational speed is It is supposed to compensate.

That is, at the end timing of the downshift (synchronization timing of the one-way clutch), the turbine rotation speed Nt of the automatic transmission is the output shaft rotation speed No multiplied by the gear ratio I after the downshift (No x Although it can be said that it corresponds to I), it is often difficult to install the turbine rotation speed sensor from the viewpoint of securing cost and space. Therefore, in this case, the turbine rotation speed Nt is set to, for example, the engine rotation speed. Must be estimated by Ne.

In this case, generally, when the power is turned on, the engine rotation speed Ne is always higher than the turbine rotation speed Nt by the slip of the torque converter, but this slip amount generally depends on the engine load. For this reason,
As shown in the above equation (2), the engine speed Ne
Is greater than a value obtained by subtracting a predetermined value N1 depending on the engine load from No × I, the vicinity of the end of the downshift is detected.

[0009]

However, when the start timing of the torque down of the engine is detected based on the equation (2) as described above, the proper start timing cannot always be detected in reality. There was a problem.

It is considered that this is because, for example, even if the engine load is the same, if the change rate of the engine load is different, the actual slip amount is different.

The present invention has been made in view of such a conventional problem, and the start timing for reducing the engine torque at the time of power-on downshift is Ne ≧ No × I.
When the change rate of the engine load is large, the predetermined value N2 is set to be large, and when the change rate of the engine load is small, the predetermined value N2 is set to be small so that only the engine rotation speed Ne is set. The purpose is to detect a more accurate start timing even though it is detected by

[0012]

The present invention reduces the engine torque during a power-on downshift to
In an automatic transmission and an engine control device configured to reduce a shock at the end of a shift, a means for detecting a change rate of an engine rotation speed, an output shaft rotation speed of the automatic transmission, and an engine load, and an engine rotation speed. Is Ne, the output shaft rotation speed of the automatic transmission is No, the gear ratio of the automatic transmission after downshifting is I, and N2 is a predetermined value, Ne ≧ No × I−N2 (1) is satisfied. When the engine torque reduction control is started, the predetermined value N2 is increased when the change rate of the engine load is large, and the predetermined value N2 is set when the change rate of the engine load is small. The above problem is solved by setting the value N2 small.

The rate of change of the engine load may be calculated by calculating the rate of change of the detected values such as the accelerator opening, the throttle opening, the intake air amount, the intake pipe negative pressure and the like.

[0014]

FIG. 4 qualitatively shows changes in the engine speed Ne and the output speed No of the automatic transmission during a downshift from the third speed to the second speed at the same vehicle speed. .

In the figure, the alternate long and short dash line shows the engine rotation speed Ne when the accelerator pedal is rapidly depressed (the engine load change rate is large), and the solid line is a slow pedal (the engine load change rate is small).
The engine rotation speed Ne at the time of is shown.
Both lines have the same throttle opening at the time of shift determination. When the accelerator pedal is depressed quickly, the low throttle opening (small slip amount) immediately before the shift determination is changed to the high throttle opening (large slip amount). At this time,
The engine rotation speed Ne cannot follow the change in the accelerator opening degree, and the change is gradual. This is considered to be due to the transient characteristics of the engine output performance. As a result, the change in slip amount also becomes gentle.

On the other hand, when the accelerator pedal is depressed late, there is no response delay in the output performance of the engine because the change in throttle opening is small, and the slip amount is equal to the steady state value.

That is, this means that the mode of change of the engine rotation speed Ne differs depending on whether the accelerator pedal is fast or slow, that is, the rate of change of the engine load.

However, conventionally, the engine torque reduction timing at the time of downshift is Ne ≧ No × I−N1, and this N1 is set only depending on the engine load (for example, the throttle opening θ) itself. Therefore, in this case, N1 is the same, and therefore, the engine speed Ne has a slow rising speed and is directly influenced by the start timing. That is, in the case of downshift, the turbine rotation speed Nt increases due to the shift, but in the case of power-on, the engine rotation speed Ne always rises in a state of exceeding the turbine rotation speed Nt during this period. However, when the accelerator pedal is quickly depressed, the absolute value of the engine rotation speed Ne does not rise easily together with the fact that the engine rotation speed Ne originally starts from a low state. Not satisfied. On the other hand, in the opposite case, it will be established early.

Therefore, if the predetermined value N1 is set in accordance with the large change rate of the engine load, the engine is changed from the stage far before the end of the gear shift (from the beginning depending on the case) when the load change rate is small. Since the rotation speed Ne exceeds the threshold value, engine torque reduction is executed early and output performance is deteriorated. Conversely, if N1 is set when the load change rate is small, it is true when the load change rate is large. The engine torque could not be reduced in time for the shift end time point (the one-way clutch synchronization time point), resulting in a shift shock.

The present invention adopts the equation Ne ≧ No × I−N2 (1) as an expression for determining the start timing, and when the engine load change rate is large, this predetermined value N2 is set to a large value. On the other hand, when the change rate of the engine load is small, the predetermined value N2 is set to be small, so that such a problem can be solved.
It becomes possible to start the torque reduction of the engine at an optimum timing regardless of the change state of the engine load.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 shows an overall outline of an automatic transmission for a vehicle and an engine to which this embodiment is applied.

This automatic transmission is provided with a torque converter 20 as its transmission portion, an overdrive mechanism portion 40, and an underdrive mechanism portion 60 having three forward stages and one reverse stage.

The torque converter 20 includes a pump 2
1, a turbine 22, a stator 23, and a lockup clutch 24. The pump 21 is connected to the crankshaft 10 of the engine 1, and the turbine 22 is connected to the carrier 41 of the planetary gear unit in the overdrive mechanism unit 40.

In the overdrive mechanism 40, the planetary pinion 42 rotatably supported by the carrier 40 is provided with a sun gear 43 and a ring gear 4.
It meshes with 4. A clutch C0 and a one-way clutch F0 are provided between the sun gear 43 and the carrier 41, and a brake B0 is provided between the sun gear 43 and the housing Hu.

The underdrive mechanism section 60 is provided with two rows of front and rear sides as a planetary gear unit. This planetary gear device includes a common sun gear 61, ring gears 62 and 63, and a planetary pinion 6.
4, 65 and carriers 66, 67.

The ring gear 44 of the overdrive mechanism section 40 is connected to the ring gear 62 via a clutch C1. Further, the link gear 44 and the sun gear 61
A clutch C2 is provided between and. Further, the carrier 66 is connected to the ring gear 63, and the carrier 66 and the ring gear 63 are connected to the output shaft 7.
It is connected to 0.

On the other hand, the carrier 67 and the housing Hu
A brake B3 and a one-way clutch F2 are provided between the sun gear 61 and the housing Hu, and a brake B2 is provided between the sun gear 61 and the housing Hu via a one-way clutch. A brake B1 is provided between and.

This automatic transmission is provided with the transmission section as described above, and the throttle sensor 10 for detecting the throttle opening θ reflecting the load state of the engine 1.
0, the automatic transmission control computer 1 to which signals such as a vehicle speed sensor 102 (a sensor for detecting the rotation speed No of the output shaft 70 of the automatic transmission) for detecting the vehicle speed are input.
04A, electromagnetic solenoid valves S1 to S in the hydraulic control circuit 106 according to a preset shift pattern.
3 is driven and controlled, and as shown in FIG. 3, the engagement of each clutch, brake, etc. is combined to perform shift control.

In FIG. 3, the ∘ mark indicates that the clutch or the brake is engaged, and the ∘ mark indicates that the one-way clutch is engaged (synchronized) when the power is turned on.

The electromagnetic solenoid valves S1 and S2 are
The underdrive mechanism unit 60 controls the first speed state to the third speed state, and the electromagnetic solenoid valve S3 controls the lockup clutch 24 of the torque converter 20.

In FIG. 2, reference numeral 110 denotes a shift position sensor, which is operated by the driver to set N,
Detecting the positions of D, R, etc., 112 is a pattern select switch for selecting E (economical traveling), P (parking traveling), etc., and 114 is a crank angle sensor for detecting the engine speed. 116 is a foot brake, and 118 is a brake switch for detecting the operation of a side brake.

The engine 1 is controlled by the engine control computer 104B in terms of fuel injection amount and ignition timing, and the engine torque is reduced or restored to the engine control computer 104B from the automatic transmission control computer 104A. A signal SG1 to the effect that it should be input is input.

Engine control computer 104
B controls the engine 1 so that the engine torque is reduced or restored on the basis of a command from this signal SG1 from the automatic transmission control computer 104A.

A well-known structure can be adopted as the structure itself for reducing the engine output. For example, a method of delaying the ignition timing (retard control) may be adopted, or a configuration in which a sub-throttle valve is provided and the sub-throttle valve is opened and closed by a motor may be adopted. In this embodiment, the engine torque is reduced by the retard control.

Next, FIG. 5 shows a control flow executed by the automatic transmission control computer 104A from downshift shift determination to engine torque control execution.

First, at step 202, the rate of change dθ of the throttle opening θ is calculated. The calculation of the change rate dθ of the throttle opening θ is always performed.

In step 204, it is judged whether or not the shift judgment is made. That is, here, it is determined whether or not the downshift determination to be the target of the present embodiment has been made, including the determination as to whether or not the power is on.

If the power-on downshift is not performed, the process returns to step 202. On the other hand, if there is a power-on downshift gear shift determination here, the routine proceeds to step 206, where the change rate dθ of the throttle opening θ that is constantly calculated at step 202 is settled.

At step 208, it is judged if the rate of change dθ is smaller than the threshold value α. That is, it is determined here whether the engine load change rate is large. dθ is α
If it is smaller than that, that is, if the change rate of the engine load is small, the routine proceeds to step 210, where various control constants are read when dθ <α. Specific reading parameters include TR, T11, T12, To, and a retard amount in addition to the information N2A related to N2 in the equation (1). These values are mapped in advance for each type of downshift. Here, TR is a timer from the start of torque reduction to the recovery, To is the time when it is recovered (the engine torque is recovered over the time of To), and T11 is to prevent erroneous determination. , A guard timer for not determining the start timing of the engine torque from the time the shift command is issued to T11, and T12 forcibly changes the engine torque after T12 after starting the reduction of the engine torque. The parameters indicating the guard timer for resetting are respectively shown.

When it is determined in step 208 that the rate of change dθ is larger than the predetermined value α, the routine proceeds to step 212, where the control constant when dθ ≧ α is similarly read from the preset map.

In step 214, the start timing of the engine torque reduction is determined based on the control constants thus read depending on the magnitude of the change rate dθ of the throttle opening θ.

In this embodiment, the engine rotation speed Ne is No due to the reasons of computer calculation and other reasons.
A value obtained by uniformly subtracting a relatively large value β from × I (No ×
The start timing is determined by determining whether it has become larger than the value obtained by adding N2A to (I-β).

That is, in this embodiment, (N2A-β) corresponds to N2 in the equation (1). Therefore, in this embodiment, N2A in step 210 (dθ <α) is N2A in step 212 (dθ ≧ α).
It is set larger than 2A, resulting in dθ <α
The part corresponding to N2 in equation (1) is small, and dθ
When ≧ α, the portion corresponding to N2 in the equation (1) is made large.

As a result, the engine torque reduction (retardation control) can be started and ended at an optimum timing regardless of how the engine load changes depending on the type of each shift. Has become.

[0046]

As described above, according to the present invention, it is possible to obtain the excellent effect that the engine torque reduction control during the power-on downshift can always be started at the optimum timing.

[Brief description of drawings]

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

FIG. 2 is an overall schematic configuration diagram of an automatic transmission for a vehicle and an engine to which the present invention is applied.

FIG. 3 is a diagram showing engagement states of the friction engagement devices and the one-way clutch of the automatic transmission.

FIG. 4 is a diagram showing a change state of an engine speed when a power-on downshift from a third speed stage to a second speed stage is executed.

FIG. 5 is a flowchart showing a control flow executed by the apparatus of the above embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine Fo, F1, F2 ... One-way clutch 20 ... Torque converter 40 ... Overdrive mechanism part 60 ... Underdrive mechanism part 104A ... Automatic transmission control computer 104B ... Engine control computer

Claims (1)

[Claims] 1. An automatic transmission and an engine control device configured to reduce a shock at the end of a shift by reducing an engine torque during a power-on downshift, and an engine rotation speed and an output shaft of the automatic transmission. A means for detecting the rotational speed and the rate of change of the engine load, the engine rotational speed is Ne, the output shaft rotational speed of the automatic transmission is No, and the gear ratio of the automatic transmission after downshifting is I, N.
When a predetermined value is set to 2, Ne ≧ No × I−N2 (1) is satisfied, a unit for setting the start timing of the engine torque reduction control is provided, and a change in the engine load. An automatic transmission and an engine control device, wherein the predetermined value N2 is set large when the rate is large, and the predetermined value N2 is set small when the change rate of the engine load is small.