JPH10278635A - Transmission control device for automatic transmission - Google Patents

Abstract

(57) [Summary] In a power-on downshift, only release-side hydraulic pressure feedback control based on a change in input rotation speed is performed, so that the release-side hydraulic pressure is increased, and the durability of the friction material is reduced. Engine blowing occurs due to a delay in hydraulic response. . A disengagement side pressure P _A, the input rotation speed variation rate d
Feedback control is performed so as to keep _NS at a constant value. When the amount of change in the input rotational speed N _T has reached the predetermined value N _TS, the torque down control of the engine is started, reduction amount T _ca of the engine control amount T _c is calculated by the input rotational speed change rate dN _TS, predetermined gradient Torque down. Engagement hydraulic pressure P _B is restored amount T _cb starts the sweep-up toward the target value P _TB on the basis of the sweep gradient dP _B is calculated and the torque return at a predetermined gradient.

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 mounted on an automobile, and more particularly, to a disengagement-side friction engagement element and a power-on state in which power is transmitted from an engine in a wheel direction. The present invention relates to a shift control device for downshifting by gripping an engagement-side friction engagement element.

[0002]

2. Description of the Related Art Generally, a power-on downshift is performed by depressing an accelerator pedal due to insufficient torque during running.

Conventionally, there is a method disclosed in Japanese Patent Application Laid-Open No. 5-332438 as a speed change method during the power-on downshift. In this system, the hydraulic pressure of the disengagement (high speed stage) side frictional engagement element is feedback-controlled so that the input shaft rotation speed change rate matches a target value, and the input shaft rotation speed (number) is controlled.
Is increased toward the low-speed synchronous rotation speed. On the other hand, the cumulative value of the supplied oil amount is sequentially obtained from the time when the supply of the hydraulic pressure to the engagement (low-speed) side frictional engagement element is started. Is reached, the release side frictional engagement element is completely released, and the engagement side frictional engagement element is completely engaged.

[0004]

The point in time at which the cumulative value of the supplied oil amount of the engagement-side friction engagement element reaches a predetermined determination value is as follows.
This means that the engagement-side frictional engagement element has completed an invalid stroke (a piston stroke that is brought to a state immediately before having a torque capacity), and thereby the gripping in an accurate synchronous state is intended. In this method, the change in the input shaft rotation speed during gear shifting is performed only by feedback control of the release hydraulic pressure.

Accordingly, as shown by a dashed line in FIG. 3, the release side hydraulic pressure P _A ′ is controlled to be relatively high, which may impair the durability of the friction material of the release side friction engagement element. There is a possibility that a malfunction such as engine blowing may occur due to a hydraulic response delay or the like during the feedback control of the release hydraulic pressure.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a shift control device for an automatic transmission which solves the above-mentioned problems by performing torque reduction control of the engine together with the feedback control of the release hydraulic pressure. .

[0007]

According to a first aspect of the present invention, there is provided a motor vehicle, comprising: an input shaft which is inputted from an engine output shaft, and the input rotation is shifted by switching a transmission path by connecting and disconnecting a plurality of friction engagement elements; An automatic transmission mechanism for outputting the speed-changed rotation to the wheels; and a hydraulic servo (9, 10) for connecting and disconnecting the friction engagement elements, and transmitting power from the engine output shaft to the wheels. In an automatic transmission, in the power-on state, one of the friction engagement elements is disengaged and the other is engaged to perform a downshift, and the input rotation speed is detected to detect the input rotation speed. and means (5), the hydraulic servo (9, 10) in communication with the hydraulic pressure (P _a, P _B) pressure regulating means pressure regulates the (SLU, SLS) and an engine operation means for operating the engine torque (8) , the change in the input rotational speed (N _T) ( A hydraulic control means comprising a feedback control (FB) for controlling the oil pressure to the N _S) the release side frictional engagement element hydraulic servo on the basis of (1a), the input rotational speed of change during the feedback control is predetermined characteristics And an engine control means (1b) for controlling the engine operation means (8) so as to satisfy the following.

According to a second aspect of the present invention, the rate of change (d) of the input rotation speed during the speed change is set in the down state (T _ca ) of the torque control amount (T _c ) by the engine control means (1b).
The shift control device for an automatic transmission according to claim 1, wherein the shift control device is set based on _NTS ).

According to a third aspect of the present invention, the torque reduction by the engine control means is performed by a predetermined value (N) in which a change amount (ΔN) of the input shaft speed from the start of the shift control is set in advance.
3. The shift control device for an automatic transmission according to claim 1, which starts at a point where _TS ).

According to a fourth aspect of the present invention, the hydraulic pressure (P _B ) to the hydraulic servo for the engagement-side frictional engagement element starts rising toward engagement (dP _B > 0). The shift control device for an automatic transmission according to claim 1, wherein the control in the torque down direction by the engine control means (1b) is stopped.

According to a fifth aspect of the present invention, there is provided the engine according to a sweep gradient (dP _B ) in which a hydraulic pressure (P _B ) to the hydraulic servo for the engagement-side frictional engagement element rises toward the engagement. Return slope from torque down by control means (T _cb )
The shift control device for an automatic transmission according to any one of claims 1 to 4, wherein

[Operation] Based on the above configuration, power-on
In the downshift, feedback control (FB) of the release hydraulic pressure (P _A ) is started when the input rotation speed change amount (ΔN) reaches a predetermined value (N _S ), and the input rotation speed change rate (dN _S ) is reduced. Pressure regulating means (SL
S or SLU). Then, the change amount of the input rotation speed (N _T ) is a predetermined value (N _TS ) set in advance.
, The engine control means (1b) starts the engine torque down control.

For the torque down, the reduction amount (T _ca ) is calculated based on, for example, the input rotational speed change rate (acceleration dN _TS ), and when the gear shift is completed, the torque down is swept down by a gradient such that the reduction amount becomes the same. The torque reduction is stopped when the engagement side hydraulic pressure (P _B ) starts sweeping up to, for example, a target value (P _TB ). Then, for example, the return amount (T _cb ) is calculated based on the sweep gradient (dP _B ) of the engagement side hydraulic pressure, and the torque is controlled at such a gradient that the torque control amount (T _c ) becomes 0 at the time of completion of the shift control. The control amount sweeps up.

The reference numerals in the parentheses are for comparison with the drawings, but do not limit the configuration of the present invention.

[0015]

According to the first aspect of the present invention, since the torque-down control is performed during the feedback control of the release-side hydraulic pressure, the release-side hydraulic pressure can be reduced, and the friction material of the release-side frictional engagement element is reduced. , And the amount of control of the release hydraulic pressure in the feedback control can be reduced to prevent the occurrence of engine blowing due to a delay in hydraulic response and the like.

According to the second aspect of the present invention, since the torque-down state is set on the basis of the rate of change of the input speed, a gradual change in the speed such as kick down and a slight depression of the throttle pedal cause a gentle rotation. Even when the input rotation speed gradient is different due to a change or the like, an appropriate torque-down state can always be set, and engine blowing and output torque fluctuation can be prevented.

According to the third aspect of the present invention, since the torque reduction is started based on the input shaft rotation change amount from the start of the shift control, the durability of the friction material is reliably prevented from decreasing from a high vehicle speed to a low vehicle speed. it can.

According to the fourth aspect of the present invention, the stop of the torque reduction is synchronized with the start of the increase of the engagement side hydraulic pressure. Generation can be prevented, and the output shaft torque can be smoothly increased.

According to the fifth aspect of the present invention, since the return gradient from the torque down is set in accordance with the sweep gradient of the engagement side hydraulic pressure, it is not affected by the sweep gradient and always provides an accurate response. The gear can be shifted and the engine blowing can be reliably prevented.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present automatic transmission has a number of frictional engagement elements such as clutches or brakes, and an automatic transmission in which the transmission path of a planetary gear is selected by appropriately connecting and disconnecting these frictional engagement elements. A mechanism (not shown) is provided, and the input shaft of the automatic transmission mechanism is connected to an engine output shaft via a torque converter, and the output shaft is connected to drive wheels.

FIG. 1 is a block diagram showing electric system control. Reference numeral 1 denotes a control unit (ECU) comprising a microcomputer (microcomputer), an engine rotation sensor 2 and a throttle opening for detecting a driver's accelerator pedal depression amount. A degree sensor 3, a sensor 4 for detecting an actual throttle opening in the engine, a sensor 5 for detecting an input shaft rotation speed (= turbine rotation speed) of a transmission (automatic transmission mechanism),
Signals from a vehicle speed (= automatic transmission output shaft rotation speed) sensor 6 and an oil temperature sensor 7 are input, and an electronic throttle system (engine operation means) 8 for controlling an engine throttle and a linear solenoid of a hydraulic circuit Output to valves (pressure regulating means) SLS and SLU. The control unit 1 controls the linear solenoid valve SLS or SL
U and an engine control means 1b for transmitting a throttle opening command to the electronic throttle system 8. The hydraulic control means 1a controls the release-side hydraulic pressure to the input rotational speed. The engine control means 1b includes a feedback control FB that regulates the pressure so that the rate of change becomes a constant predetermined value. I do.

FIG. 2 is a diagram schematically showing a hydraulic circuit.
A plurality of friction engagement elements having the two linear solenoid valves SLS and SLU and switching a transmission path of a planetary gear unit of an automatic transmission mechanism to achieve, for example, a forward fourth speed or a fifth speed and a reverse first speed. A plurality of hydraulic servos 9 for connecting and disconnecting (clutches and brakes)
It has 0. Further, the linear solenoid valve S
Solenoid modulator pressure is supplied to input ports a ₁ and a ₂ of LS and SLU, and control oil pressures from output ports b ₁ and b _{2 of} these linear solenoid valves are applied to control oil chambers of pressure control valves 11 and 12, respectively. 11a and 12a. The pressure control valves 11 and 12 supply line pressures to the input ports 11b and 12b, respectively, and the pressure regulation from the output ports 11c and 12c regulated by the control hydraulic pressure is applied to the shift valves 13 and 15 respectively. It is supplied to the hydraulic servos 9 and 10 as needed.

This hydraulic circuit is for showing the basic concept. The hydraulic servos 9 and 10 and the shift valves 13 and 15 are symbolically shown.
A number of hydraulic servos are provided corresponding to the automatic transmission mechanism, and a number of shift valves for switching the hydraulic pressure to these hydraulic servos are also provided. Further, as shown in the hydraulic servo 10, the hydraulic servo has a piston 19 which is fitted to the cylinder 16 in an oil-tight manner by an oil seal 17, and the piston 19 is provided with a pressure control valve 12 acting on a hydraulic chamber 20. The outer friction plate 22 and the inner friction material 23 come into contact with each other based on the pressure-adjusted hydraulic pressure from the first and second springs, and move against the return spring 21. Although the friction plate and the friction material are shown by the clutch, it is needless to say that the friction plate and the friction material also correspond to the brake.

[0024] Then, the described shift control apparatus according to the present invention along the FIG. 3, based on FIG. 4, will be described disengagement hydraulic pressure P _A in the time the downshift by the clutch engagement-switching gear during power-on.

During driving, when the driver feels that the torque is insufficient and depresses the accelerator pedal, based on signals from the throttle opening sensor 3 and the vehicle speed sensor 6, the control unit 1 determines a downshift based on a map. . Then, after a predetermined delay time from the shift determination, time measurement is started and shift control is started (S1). At the start time (t = 0),
_A control signal is output to the linear solenoid valve SLS (or SLU) at which the release hydraulic pressure PA becomes the engagement pressure _PW, and the release friction engagement element is engaged (S2). And
The release torque T _A is calculated by a function of the input torque T _t (S2). The input torque _Tt is obtained by calculating an engine torque based on a throttle opening and an engine speed by a map, further calculating a speed ratio from an input / output speed of a torque converter, and obtaining a torque ratio by a map based on the speed ratio.
It is determined by multiplying the engine torque by the above torque ratio. Further, the release-side torque T _A is obtained by involving the torque sharing ratio and the like in the input torque.

Furthermore, the target pressure P _TA of the release-side based on the release side torque T _A is calculated (S4). That is, the effective radius of the disengagement side frictional engagement element × the piston area × the number of sheets × the friction coefficient is A, and the disengagement side piston stroke pressure (return spring pressure)
Is B, the release side hydraulic pressure P _A is [P _A = (T _A /
A) + B]. And, the release side hydraulic pressure P _A
Sweep down toward from the engagement pressure P _W to the target hydraulic pressure P _TA (S5). Then, when the release-side hydraulic pressure P _A becomes the target oil pressure P _TA (S6), the predetermined gradient [(P _TA
−P _W ) / t _TA ] is stopped, and the target oil pressure P _TA is maintained (S7).

[0027] Then, when it exceeds a rotational speed N _S of variation ΔN from the shift start of input rotational speed N _T by the input shaft rotational speed sensor 5 is set in advance (S8), the feedback control FB is started (S9 ). The feedback control includes:
Input speed change rate dN _S is the pressure-regulating control disengagement side pressure P _A to be constant target value. In the feedback control, a predetermined time t _SE for performing piston stroke control of the engagement-side hydraulic pressure (control of moving the piston until just before the friction material comes into contact and has a torque capacity) described later elapses (S10). ), and continued until the engagement side hydraulic pressure P _B reaches the target oil pressure P _TB which will be described later (S11). When the feedback control ends, the release hydraulic pressure P _A
Sweeps down at a predetermined gradient δP _FA (S12), the sweep down continues until the hydraulic pressure is drained (S13), and the control of the release hydraulic pressure ends.

On the other hand, as shown in the flowchart of FIG. 5, the engagement-side hydraulic pressure P _B starts to be measured at the same time as the shift control is started (S1), and at the same time, becomes equal to the predetermined pressure P _S1. The signal is output to the linear solenoid valve SLS (or SLU) (S21), and is held at the predetermined pressure P _S1 for a predetermined time t _SA (S22). The predetermined pressure P _S1 is a pressure required to fill the hydraulic chamber 20 of the hydraulic servo and move the piston 19 so that the friction members 22 and 23 come into contact (fast fill pressure). After the lapse of the predetermined time t _SA , the engagement side hydraulic pressure P _B becomes a predetermined gradient [(P _S1 −P _S2 ) / t.
Swept down _SB] (S23), when the engagement hydraulic pressure P _B reaches a predetermined low pressure P _S2 (S24), the sweep-down is stopped and held in the predetermined low pressure P _S2 (S25). The predetermined low pressure P _S2 is set to a pressure that is equal to or higher than the piston stroke pressure and does not cause a change in the rotation of the input shaft, and the predetermined low pressure P _S2 is held until the time t reaches a predetermined time t _SE (the piston Stroke control) (S26).

[0029] Then, release side torque share T _B is calculated by a function based on the input torque T _t and the disengagement side pressure P _A (S27). Furthermore, on the basis of the disengagement side torque share T _B, engagement hydraulic pressure P _TB immediately before the rotation change of the input rotational speed N _T begins is calculated (S28). Then, based on the engagement hydraulic pressure P _TB , a predetermined gradient is calculated for a predetermined time t _TB set in advance [(P _TB −PS ₂ ) / t _TB ], and the engagement side hydraulic pressure is swept up based on the gradient. (S29). As a result of the sweep-up, the engagement torque increases, and the oil pressure rises to the state immediately before the input rotation speed change starts, that is, to the calculated predetermined target engagement oil pressure _PTB (S30).

[0030] Then, by the sweep-up, the engagement-side oil pressure P _B when it reaches the target engagement pressure P _TB, the inertia phase rotation change of the input shaft rotational speed is started is expected to be finished. That is, N ₁ is the input shaft rotation speed at the start of shifting,
g _{i + 1} the pre-shift gear ratio, after shifting the g _i gear ratio, when the N _TE and the rotation variation during the shift completion _{(ΔN), ΔN = N TE} = N 1 (g i + 1 -g) becomes , The shift is completed.

[0031] Then, the time counting time t _F is set at (S31), the state is in state and substantially corresponds to the inertia phase has ended. Furthermore, a relatively steep oil pressure change δP _FB
Is set, and the oil pressure suddenly sweeps up due to the change in the oil pressure (S32), and a predetermined time t _FB set to a time sufficient to increase to the engagement pressure has elapsed from the clock time t _F. In this state (S33), the hydraulic control on the engagement side is completed.

Next, the engine torque control will be described with reference to FIG. As described above, the input rotation speed N _{T is obtained} by the feedback control (S9) of the release-side friction engagement element.
There rises at a constant gradient, the change amount ΔN from at the start of control of the input rotational speed reaches a preset predetermined value N _TS, the torque down control of the engine is operated (S41). If the torque-down timing is always constant, if the number of rotations at the start of shifting is large, that is, if the amount of change in rotation during shifting is large, the amount of heat generated by the disengagement-side friction engagement element also increases. Is delayed, the durability of the friction material may be impaired. However, in the present engine torque control, the start point of the torque reduction is set to the input rotation speed _NT (ΔN = 0) at the start of the shift control as described above. (ΔN ≧ N _TS ), it is possible to prevent a decrease in the durability of the disengagement-side friction engagement element from a high vehicle speed to a low vehicle speed.

[0033] Then, to calculate the predetermined value N rate of change of the input speed in the _TS i.e. acceleration dN _TS, based on said change rate, and calculates a torque reduction amount T _ca by proportional function shown in FIG. 7 (a) ( S42). Then, after setting the control amount _Tc of the engine torque to 0 (S43),
The control amount is controlled. If the torque reduction amount is set based on the input rotation speed ΔN, the reduction amount will always be constant even when the rising gradient of the rotation speed is different, and if the rotation gradient is steep as in kick down, engine blowing will occur. When the rotation gradient is gentle, the output torque T _O changes. However, since the reduction amount is set by the rotation change rate dN _TS as described above,
The optimum reduction amount is always set regardless of the rotation gradient, and the engine blowing and the fluctuation of the output torque can be prevented.

The torque control amount _Tc is equal to the torque reduction amount _Tca at the time when the shift is completed.
Assuming that such a gradient, that is, the input rotation speed (change amount) from the start of the shift is ΔN, the torque control amount T _c
Sweeps down _{T c = -T ca × (ΔN} -N TS / N TE -N TS) (S44). The sweep-down is performed when the engagement side oil pressure P _B changes in the rising direction, that is, when the change rate dP _{B of the} oil pressure becomes positive (S45), or when the input rotation speed change amount ΔN is changed to the post-shift input rotation speed N. _It continues until it becomes _TE (S46). At this time, since the control in the engine torque down direction is stopped in synchronization with the start of the sweep-up of the engagement side oil pressure P _B , the two-stage control by raising the engagement side oil pressure and stopping the torque reduction at different timings is performed. The occurrence of shock can be prevented.

[0035] Then, dP _B> 0 or .DELTA.N ≧ N becomes the _TE, the engagement hydraulic pressure P _B of the rate of change dP _B i.e. the target value P
_The return amount T _cb is calculated based on the inverse gradient function as shown in FIG. 7B by the sweep gradient toward _TB (S47).
Then, the target pressure P _TB engagement hydraulic pressure P torque control amount T _c of the ratio multiplied in the return amount T _cb of _B to
In step S48, a sweep-up is performed from the torque control amount [T _ca ] interrupted in step S45 or S46. [T _ca ] in step S48
Is the torque control amount at which the sweepdown in step S44 has been interrupted, and often does not match the reduction _Tca calculated in step S42. The sweep-down is terminated when the torque control amount T _c exceeds 0 (S49), in general the point, the point where the engagement hydraulic pressure P _B reaches the target value P _TB, i.e. the inertia phase is finished When the input rotational speed _NT reaches the post-gear rotational speed _NTE , the engine torque control ends.

At this time, if the return gradient of the torque control amount is constant, if the sweep gradient of the engagement side hydraulic pressure is large, the rise of the torque is delayed with respect to the torque capacity of the engagement side frictional engagement element. If the response is degraded and the sweep gradient of the engagement side hydraulic pressure is small, the rise of the torque with respect to the torque capacity is accelerated, causing engine blowing, but the return amount gradient is reduced as described above. By setting according to the sweep gradient, it is possible to reliably prevent the above-described deterioration of the response and the engine blowing.

[0037] Thus, the torque-down control of the engine is performed with feedback control of the disengagement side pressure P _A described above, the disengagement side pressure P _A, kept lower than the ones of the prior art (P _A ') Therefore, the durability of the friction material of the friction engagement element can be improved, and the engine can be prevented from being blown due to a delay in hydraulic response.

[Brief description of the drawings]

FIG. 1 is an electric block diagram according to the present invention.

FIG. 2 is a diagram schematically showing a hydraulic circuit according to the present invention.

FIG. 3 is a time chart according to the embodiment of the present invention.

FIG. 4 is a flowchart showing the hydraulic control on the release side.

FIG. 5 is a flowchart showing hydraulic control on the engagement side.

FIG. 6 is a flowchart showing the engine torque control.

7A is a diagram showing a reduction amount of engine torque control, and FIG. 7B is a diagram showing a return amount of engine torque.

[Explanation of symbols]

1 control unit 1a hydraulic control unit 1b engine control unit 5 input rotational speed detecting means (sensor) 8 engine operating means (electronic throttle system) 9,10 hydraulic servo N _T input revolution speed N _TS predetermined value dN _TS input rotational speed change rate P _A disengagement side pressure P _B engagement hydraulic pressure dP _B sweep gradient T _C engine torque (control value) T _ca down (reduction amount) T _cb return state (return amount)

Continued on the front page (72) Inventor Masao Saito 10th Takane, Fujiimachi, Anjo, Aichi Prefecture Inside Aisin AW Co., Ltd. (72) Inventor Takayuki Kubo 10th Takane, Fujiicho, Anjo, Aichi Prefecture Aisin Ai In GW Corporation

Claims (5)

[Claims] 1. An automatic transmission mechanism that receives an input from an engine output shaft, shifts the input rotation by switching a transmission path by connecting and disconnecting a plurality of friction engagement elements, and outputs the shifted rotation to wheels. And a hydraulic servo that disconnects and connects the friction engagement elements. In a power-on state in which power is transmitted from the engine output shaft to wheels, one of the friction engagement elements is released. An automatic transmission formed by engaging the other one and downshifting, wherein an input rotation speed detecting means for detecting the input rotation speed, a pressure adjusting means for adjusting a hydraulic pressure communicated with the hydraulic servo, An engine operating means for operating an engine torque; a hydraulic control means including feedback control for controlling a hydraulic pressure to the hydraulic servo for the disengagement side frictional engagement element based on a change in the input rotational speed; And an engine control means for controlling the engine operating means so that the change in the input rotation speed has a predetermined characteristic during the torque control. 2. The shift control device for an automatic transmission according to claim 1, wherein a down state of the torque control amount by the engine control means is set based on a change rate of an input rotation speed during a shift. 3. The automatic transmission according to claim 1, wherein the torque reduction by the engine control means is started at a point where a change amount of the input shaft rotation speed from the start of the shift control reaches a predetermined value. Transmission control device. 4. In synchronization with the start of the hydraulic pressure to the engagement-side friction engagement element hydraulic servo for engagement,
4. The shift control device for an automatic transmission according to claim 1, wherein the control in the torque down direction by the engine control unit is stopped. 5. 5. In accordance with a sweep gradient in which the hydraulic pressure to the engagement-side friction engagement element hydraulic servo rises toward engagement,
The shift control device for an automatic transmission according to any one of claims 1 to 4, wherein a return gradient from a torque reduction by the engine control means is set.