JPH0833175B2 - Automatic transmission for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic transmission for a vehicle, and more particularly, to technology for preventing shift shock in a torque converter type automatic transmission mounted on a vehicle.

<Prior Art> In a torque converter type automatic transmission, in order to reduce the shift shock, the oil discharged from the oil pump is adjusted to a suitable line pressure according to the engine operating conditions such as the throttle valve opening of the engine. After the adjustment, it is generally supplied to a hydraulic circuit that controls each shift element of the automatic transmission (see Japanese Utility Model Laid-Open No. 1-106660).

<Problems to be Solved by the Invention> However, if the line pressure is set low in order to avoid gear shift shocks, the fastening force of gears and the like weakens, unnecessary slip occurs, and transmission efficiency decreases significantly, and in the worst case Since there is a risk that the clutch etc. will be broken due to friction, the actual situation is that the line pressure cannot be set low enough to avoid gear shift shock.

Further, as described above, the line pressure control alone cannot satisfactorily avoid the shift shock. Therefore, the timing at which the drive wheel torque fluctuations due to the shift occur is predicted after adjusting the line pressure, and the timing at which the drive wheel torque fluctuations occur If the engine output torque is controlled by reducing the intake air amount of the engine in accordance with the above, it is not possible to accurately predict the true torque fluctuation timing, which may rather promote the shift shock.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an automatic transmission for a vehicle that can favorably reduce gear shift shock by controlling engine output torque.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, in an automatic transmission for a vehicle configured to transmit an engine output torque to a transmission mechanism via a torque converter, the transmission mechanism A torque sensor for directly detecting the torque in the output shaft, a torque change ratio calculation means for calculating a change ratio of the torque detected by the torque sensor during a shift operation of the transmission mechanism, and a shift operation of the transmission mechanism. In order to suppress the fluctuation of the torque in the engine, the control value of the engine output torque is set according to the change rate of the torque calculated by the torque change rate calculating means during the shift operation, and the control value is set according to the control value. An engine output torque increase / decrease control means for sequentially increasing / decreasing the engine output torque is provided.

Here, it is preferable that the engine output torque increase / decrease control means performs the increase / decrease control of the engine output torque by variably controlling at least one of the opening area of the intake system, the ignition timing, and the air-fuel ratio.

<Operation> With this configuration, the torque sensor directly detects the torque at the output shaft of the speed change mechanism, and the torque change rate calculation means calculates the change rate of the torque detected by the torque sensor during the speed change operation. Then, the engine output torque increase / decrease control means sets a control value of the engine output torque according to the change rate of the torque in order to suppress the fluctuation of the torque during the shift operation of the transmission mechanism, and according to the control value, the engine output torque Increase / decrease output torque.

That is, the torque of the output shaft that directly correlates with the shift shock to the occupant of the vehicle is detected, the fluctuation of the torque is monitored during the shift operation, and the engine output torque is controlled to increase or decrease, thereby suppressing the fluctuation of the output shaft torque. This prevents the occurrence of shift shock.

The increase / decrease control of the engine output torque may be performed by variably controlling at least one of the opening area of the intake system, the ignition timing, and the air-fuel ratio.

<Examples> Examples of the present invention will be described below.

In FIG. 2 showing an embodiment, a torque converter type automatic transmission 2 is attached to an internal combustion engine 1 mounted on a vehicle (not shown) and is transmitted via the torque converter type automatic transmission 2. The engine output torque is applied to the left and right drive wheels 4a, 4b via the differential gear 3.

The internal combustion engine 1 is a control unit (ENG / C / U) for engine control which receives various detection signals from various sensors (air flow meter, crank angle sensor, water temperature sensor) (not shown) attached to the engine 1. 5, the fuel supply amount and ignition timing are controlled.

Further, in the torque converter type automatic transmission 2, the engine output torque taken out through the engine output shaft is transmitted to the speed change mechanism 7 through the torque converter 6. Here, the speed change mechanism 7 is used. The input shaft to the input shaft 8 is the input shaft 8, and the output shaft from the speed change mechanism 7 is the output shaft 9.

The AT control unit (AT / C / U) 10 for controlling the shifting operation by the torque converter type automatic transmission 2 has a signal from an inhibitor switch provided on a shift lever (not shown) operated by a driver and an accelerator pedal. The opening area of the engine intake system (that is,
Opening signal TV of the throttle valve 12 that controls the intake air amount)
O, a vehicle speed signal VSP from a vehicle speed sensor (not shown) for detecting the traveling speed of the vehicle, and further rotation speed signals of the ipt shaft 8 and the output shaft 9 respectively.
Nin, Nout, etc. are input, and the shift operation is controlled based on the input signal.

Further, in the vehicle shown in the present embodiment, a so-called traction control system that detects slippage of drive wheels from the difference in rotational speed between front and rear wheels and reduces engine output torque to detect slippage when slippage is detected ( TCS) is provided, and the TSC control unit (TCS / C / U) 13 that controls the operation of the traction control system is
An auxiliary throttle valve (second throttle valve) 14 provided on the downstream side of the throttle valve 12 when slippage of the drive wheels is detected based on the input front wheel rotation speed and rear wheel rotation speed.
By narrowing the opening of the engine, the engine output torque is reduced independently of the opening of the throttle valve 12 by the accelerator pedal 11.

Further, in this embodiment, a torque sensor 15 is provided on the output shaft 9 of the speed change mechanism 7,
The torque (hereinafter, the torque in the output shaft 9 is simply referred to as torque) taken out through the sensor is detected, and the torque detection signal is detected as ENG / C5 / TSC / C / U5.
Output to U13 and respectively. Incidentally, the detection signal of the torque sensor 15 is not necessary in the normal engine control and traction control, but the detection signal of the torque sensor 15 is necessary for the shift shock countermeasure control according to this embodiment described later.

Here, details of the torque sensor 15 will be described with reference to FIGS.
Description will be made with reference to the drawings.

As shown in FIG. 3, the torque sensor 15 is composed of a magnetostrictive shaft 31 provided in the middle of the output shaft 9 and a pair of coils L1 and L2 wound and fixed around the magnetostrictive shaft 31 as an axis. ing. In FIG. 3, reference numeral 35 denotes a ball bearing that supports the magnetostrictive shaft 31.

The magnetostrictive shaft 31 is formed of a magnetostrictive material having a high magnetic sensitivity and a small hysteresis, and a plurality of parts each forming an angle of 45 ° with respect to the axial direction in the portion surrounded by the pair of coils L1 and L2. The slits 32 and 33 are formed. The slit 32 surrounded by the coil L1 and the slit 33 surrounded by the coil L2 are tilted with respect to the axial direction so as to be orthogonal to each other.

As shown in FIG. 4, the pair of coils L1 and L2 constitute a circuit with four fixed resistors R ₁ , R ₂ , R ₃ and R ₄ having the same resistance value R and one adjusting resistor R _0. Is done.
Here, the coil L1 and the resistors R ₁ and R ₂ are connected in series, and the coil L2 and the resistors R ₃ and R ₄ are connected in series. These series circuits are connected in parallel with each other, and , An AC power source V having a frequency f is connected to both ends thereof. Furthermore, the resistance
The adjustment resistor R ₀ is connected so that it is parallel to R ₃ and R ₄ . Then, the terminal voltages V ₁ and V _{2 of} the resistors R ₃ and R ₄ are input to the differential amplifier 34, and the output v of this differential amplifier 34 is taken out as a sensor output.

That is, the self-inductance of each of the coils L1 and L2 is Becomes Here, μ is the magnetic permeability of the magnetostrictive material, N is the number of coil turns, S is the magnetic path cross-sectional area, and 1 is the average magnetic path length.

The currents i ₁ and i ₂ flowing in the coils L1 and L2 are Becomes

Further, since V ₁ = i ₁ × R and V ₂ = i ₂ × R, the sensor output v = V ₂ −V ₁ changes according to the increase / decrease in the self-inductance of each of the coils L1 and L2. .

On the other hand, when AC is applied to the coils L1 and L2, the magnetostrictive shaft 3
1 A magnetic path is formed on the surface, but slits 32, 33 inclined 45 ° to the axial direction are formed on the magnetostrictive shaft 31 as described above.
Is provided, the magnetic path is formed along the slits 32, 33. When the torque T is applied to the magnetostrictive shaft 31, a tensile stress + σ is generated in the direction of 45 ° with respect to the axial direction as shown in the figure, and a compressive stress −σ is generated in the direction perpendicular to the tensile stress + σ.

In the case of a magnetostrictive material having a positive characteristic, as shown in FIG. 5, the magnetic permeability μ increases due to the tensile stress + σ (the magnetic permeability μ decreases at the compressive stress −σ).
If torque T is added to 31, L1 (+ σ); μ increase L1 increase i ₁ decrease V ₁ decrease L2 (-σ); μ decrease L2 decrease i ₂ increase V ₂ increase An increasing output v will be generated.

In FIG. 5, magnetization I = magnetic susceptibility χ × magnetic field H, magnetostrictive material permeability μ = 1 + 4πχ, magnetic sensitivity B = H + 4πI =
H (1 + 4πχ) = permeability μ × H. Further, the output v is adjusted to zero without applying the torque T to the magnetostrictive shaft 31, and the adjustment resistance R _{0 is} adjusted so that V ₁ = V ₂ .

Next, the shift shock reduction control using the torque sensor 15 will be described according to the programs shown in the flow charts of FIGS. In this example,
The functions of the torque change ratio calculation means and the engine output torque increase / decrease control means are provided by software as shown in the flowcharts of FIGS. 6 to 8.

The program shown in the flowchart of FIG. 6 is AT / C /
This shows the shift control performed by U10. First, in step 1 (indicated as S1 in the figure; the same applies hereinafter), the opening TVO of the throttle valve 12 and the vehicle speed VSP are input.

Then, in the next step 2, the gear position nextgp corresponding to the current VSP and TVO is searched and obtained from the map of the shift pattern which is set in advance with the vehicle speed VSP and the throttle valve opening TVO as parameters.

In step 3, the current gear position curtgp is compared with the gear position nextgp corresponding to the operating condition obtained in step 2 above to determine whether or not a gear shifting operation is necessary.

Here, when the current gear position curtgp is different from the gear position nextgp corresponding to the driving condition, it means that the gear shifting operation is required. At this time, the process proceeds to step 4 and the gear shift signal is transmitted to TCS / C13 / ENG / C. Output to / U5 and TCS / C / U1
Notify 3 and ENG / C / U5 that AT / C / U10 will perform shift control.

Then, in the next step 5, the throttle valve opening degree is set in advance.
A line pressure suitable for the current shift control is searched for and obtained from the line pressure map for shifting which is stored in association with TVO.

In step 6, the current gear position in step 3
It is determined whether or not the curtgp and the gear position nextgp corresponding to the driving condition are different from each other for the first time, and if it is the first time, the process proceeds to step 7.

In step 7, the line pressure for shifting, which is obtained by searching from the map in step 5, is set as the target line pressure so as to be adjusted to the line pressure suitable for the shifting operation at this time, and the shift pressure (not shown) is set. The solenoid is controlled so that the shift operation is performed.

On the other hand, when it is determined in step 6 that it is not the first time that the current gear position curtgp and the gear position nextgp corresponding to the operating condition are different, it means that the predetermined shift control in step 7 has already been set. This program ends as it is.

Further, when it is determined in step 3 that the current gear position curtgp and the gear position nextgp corresponding to the operating condition match, the process proceeds to step 8 and the rotation speed N of the output shaft 9 and the rotation speed of the input shaft 8 with respect to the speed change mechanism 7. Nin
Calculate the ratio of and and set the result in Ratio.

Then, in the next step 9, the Ratio, which is the rotation speed ratio between the input and the output, calculated in step 8 corresponds to the gear ratio of the gear position nextgp corresponding to the operating condition searched in step 2. Or not.

Here, when the Ratio corresponds to the gear ratio of the gear position nextgp, it indicates that the actual gear is being shifted to the gear position nextgp, so the routine proceeds to step 10, where TCS / C / U13
Also, a gear change end signal is output to ENG / C / U5 to notify that the gear change operation is completed.

Further, in the next step 11, the line pressure in the non-shift state corresponding to each gear position is stored in correspondence with the throttle valve opening TVO from the stored map to correspond to the current gear position and throttle valve opening TVO. The line pressure to be obtained is searched for, and this line pressure is set as the target line pressure.

Next, the fuel control corresponding to the shift operation performed by the ENG / C / U5 will be described according to the program shown in the flowchart of FIG.

First, in step 21, the torque in the output shaft 9 detected by the torque sensor 15 is input, and in the next step 22, the torque change rate ΔT per predetermined time is calculated based on the torque input in step 9.

Then, in step 23, it is determined whether or not the speed change mechanism 7 is in the speed change operation based on the speed change signal and the speed change end signal output from the AT / C / U 10, and when the speed change operation is in progress, the torque change is performed. In order to control the engine output torque based on the ratio ΔT, the process proceeds to step 24 and thereafter.

In step 24, the fuel correction coefficient hm corresponding to ΔT calculated in step 22 is calculated from the map storing the correction coefficient hmr of the fuel supply amount corresponding to the torque change rate ΔT.
Search for r.

Here, when ΔT is a positive value and shows an increasing tendency of the torque, the fuel correction coefficient hmr is set to a value smaller than the reference value 1.0 according to the increase of the absolute value of ΔT, and The fuel supply amount Ti multiplied by the correction coefficient hmr is reduced and corrected at a larger rate as the torque increases sharply.

Further, when ΔT is a negative value and shows a decreasing tendency of torque, the fuel correction coefficient hmr is set to a value larger than the reference value 1.0 in accordance with the increase of the absolute value of ΔT, and The fuel supply amount Ti multiplied by the correction coefficient hmr is increased and corrected at a larger rate as the torque sharply decreases.

Therefore, when the torque is increasing, the engine output torque is reduced by reducing the fuel amount (making the air-fuel ratio leaner), and when the torque is decreasing, the engine output is increased by increasing the fuel amount (making the air-fuel ratio richer). Therefore, the increase / decrease of the torque during the shift operation is suppressed.

In the next step 25, the advance correction value hadv is searched for based on the calculated ΔT in step 22 from the map in which the correction value hadv of the ignition advance value corresponding to ΔT is stored. Like the fuel correction coefficient hmr, the advance correction value hadv is set to a negative value when ΔT is positive so that the engine output torque is decreased (increased) when the torque tends to increase (decrease). And retard correction,
When ΔT is negative, the map is set so that it is set to a positive value and the advance angle is corrected.

At step 26, the fuel supply amount Ti by the fuel supply device such as the fuel injection valve is calculated according to the following equation using the fuel correction coefficient hmr obtained by searching from the map based on ΔT at step 24.

Ti ← Tp × α × hmr × COEF + Ts In the above equation, Tp is the basic fuel supply amount, and Tp ← based on the intake air flow rate Q of the engine 1 and the engine rotation speed N
It is calculated as K × Q / N (K is a constant). α is an air-fuel ratio feedback correction coefficient, and is used to feedback-correct the air-fuel ratio detected via the oxygen concentration in the exhaust gas detected by the oxygen concentration sensor provided in the exhaust system to the target air-fuel ratio. Further, COEF is various correction coefficients set according to operating conditions such as the cooling water temperature of the engine 1, and Ts is a correction amount for correcting the change in the effective injection time of the fuel injection valve due to the battery voltage.

In the next step 27, correction is made based on the advance correction value hadv obtained by searching from the map in step 25, and the final ignition timing ADV is set. A map that stores the basic advance value adv for each operating region divided by the basic fuel injection amount Tp and the engine speed N is set in advance in ENG / C / U5. Here, the map is searched. The above-mentioned advance angle correction value hadv is added to the basic advance angle value adv thus obtained to set the final ignition timing ADV. Therefore, when the advance angle correction value hadv is positive, the basic advance angle value adv is advanced, and when the advance angle correction value hadv is negative, the basic advance angle value adv is retarded, resulting in engine output. The ignition timing ADV is corrected and set so as to suppress the torque change.

In this way, when the fuel supply amount Ti and the ignition timing ADV are corrected and set based on ΔT, the correction result is output in the next step 28, and the fuel supply control and the ignition are performed based on the fuel injection amount Ti. Ignition control is performed based on the timing ADV.

When the gear shifting operation is not in progress, the fuel correction coefficient hm
The fuel supply amount Ti and the ignition timing ADV are set without correction by the r and the advance correction value hadv.

In this way, if the fuel supply amount Ti (in other words, the air-fuel ratio) and the ignition timing ADV are corrected and the engine output torque is controlled to increase or decrease in the direction of suppressing the torque change in the output shaft 9 during the gear shifting operation, the gear shifting operation is performed. At drive wheels 4a, 4
It is possible to prevent a sudden change in the torque applied to b and a shift shock. However, in the present embodiment, the engine output torque is not detected by controlling the engine output torque by predicting the timing of torque fluctuation in the output shaft 9, but the engine output torque is controlled by directly detecting the torque fluctuation. By controlling the output torque, it is possible to reliably avoid the occurrence of a shift shock.

Further, if the occurrence of the shift shock can be avoided by the engine output torque increase / decrease control as described above, it is not necessary to significantly reduce the line pressure to avoid the occurrence of the shift shock.
It is possible to prevent deterioration of durability due to a decrease in line pressure.

Next, the engine output torque control during the shift operation by the TCS / C / U 13 will be described according to the program shown in the flowchart of FIG.

As described above, the TCS / C / U 13 normally detects the slip of the drive wheels and controls the engine output torque so as to restore the traction.However, in the present embodiment, the gear shift operation is performed as described later. The engine output torque is also controlled, and the control for avoiding shift shock is carried out together with the ENG / C / U5.

In the program shown in the flowchart of FIG.
First, in step 31, the torque of the output shaft 9 detected by the torque sensor 15 is input, and in the next step 32, the change rate ΔT of the torque is calculated.

In step 33, it is determined whether or not the gear shift operation is being performed based on the gear shift signal from the AT / C / U10.When the gear shift operation is being performed, the opening control of the auxiliary throttle valve 14 is performed independently of the traction control. To proceed to step 34.

In step 34, a target opening correction value Δtvo corresponding to ΔT of the calculation result in step 32 is retrieved from a map storing the target opening correction value Δtvo of the auxiliary throttle valve 14 corresponding to the torque change rate ΔT. And ask. The target opening correction value Δtvo is set to a negative value when ΔT is positive and shows a torque increasing tendency, and the opening is decreased and corrected, and when ΔT is negative and a torque is decreasing, it is positive. Is set to a value to increase the opening degree.

In the next step 35, the current auxiliary throttle valve (second
The target opening of the throttle valve) 14 is controlled based on the target opening corrected by the correction value Δtvo.

Thus, based on the torque change rate ΔT, when the torque tends to increase, the opening degree of the auxiliary throttle valve 14 (the opening area of the intake system) is reduced to reduce the engine output torque, and the torque tends to decrease. In some cases, the opening degree of the auxiliary throttle valve 14 is increased to increase the engine output torque, and the engine output torque is controlled in a direction to avoid a sudden change in the torque during the gear shifting operation. It is possible to avoid the occurrence of shock, and yet, the torque is directly detected and the auxiliary throttle valve 14
Since the opening degree of the engine is controlled, the engine output torque can be controlled in time with a sudden change in the torque.

Incidentally, in the present embodiment, the engine output torque is adjusted by controlling the fuel supply amount Ti, the ignition timing ADV and the opening degree of the auxiliary throttle valve 14 according to the torque fluctuation of the output shaft 9 detected during the gear shifting operation. , One of the three controlled objects
Only one or two may be controlled.

Further, instead of correcting the decrease of the fuel supply amount Ti, the control of stopping the fuel supply may be performed. Further, instead of the auxiliary throttle valve 14 for traction control, the opening degree of an idle speed control solenoid valve provided in an auxiliary air passage provided by bypassing the throttle valve 12 may be controlled. good.

<Effects of the Invention> As described above, according to the present invention, the torque of the output shaft of the speed change mechanism is detected, and the engine output torque is sequentially increased during the speed change operation so as to suppress the torque fluctuation based on the torque change rate. Since the increase / decrease control is performed, the engine output torque control that suppresses the torque fluctuation of the output shaft during the gear shifting operation can be performed with good timing, the occurrence of gear shift shock can be avoided with high precision, and the gear shift can be controlled by controlling the engine output torque. Since the shock is avoided, it is possible to maintain the durability of the transmission mechanism without the need to reduce the line pressure more than necessary.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, FIG. 3 is a partial sectional view showing details of a torque sensor in the same embodiment, and FIG.
FIG. 5 is a circuit diagram showing a torque detection circuit in the torque sensor shown in FIG. 3, FIG. 5 is a diagram showing torque detection characteristics of the torque sensor shown in FIG. 3, and FIGS. 6 is a flowchart showing various controls related to shock avoidance. 1 ... Internal combustion engine, 2 ... Torque converter automatic transmission, 5 ... ENG / C / U, 6 ... Torque converter, 7 ...
Speed change mechanism, 8 ... Input shaft, 9 ... Output shaft, 10 ... AT / C / U, 13 ... TCS / C / U, 14 ...
… Auxiliary throttle valve, 15… Torque sensor

Claims (2)

[Claims] 1. An automatic transmission for a vehicle configured to transmit an engine output torque to a speed change mechanism via a torque converter, and a torque sensor for directly detecting torque at an output shaft of the speed change mechanism; A torque change ratio calculating means for calculating a change ratio of the torque detected by the torque sensor during a gear shift operation of the mechanism; and, in order to suppress the variation of the torque during the gear shift operation of the speed change mechanism, during the gear shift operation, An engine output torque increase / decrease control unit that sets a control value of the engine output torque according to the change ratio of the torque calculated by the torque change ratio calculation unit, and sequentially increases / decreases the engine output torque according to the control value. An automatic transmission for a vehicle characterized by being provided. 2. The engine output torque increase / decrease control means is configured to perform increase / decrease control of the engine output torque by variably controlling at least one of an opening area of an intake system, an ignition timing, and an air-fuel ratio. The automatic transmission for a vehicle according to claim 1, wherein the automatic transmission is a vehicle.