JP3371747B2 - Transmission control device for automatic transmission - Google Patents

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 release side friction engagement element and a release side friction engagement element in a power-on state in which power is transmitted from an engine to a wheel. The present invention relates to a shift control device when a downshift is performed by changing the grip of an engagement side frictional 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 traveling.

[0003] Conventionally, as a speed change method at the time of power-on downshift, there is a method disclosed in Japanese Patent Laid-Open No. 332438/1993. This is the input shaft rotation speed (number) by feedback control of the hydraulic pressure of the friction engagement element on the release (high speed stage) side so that the input shaft rotation speed change rate matches the target value.
On the other hand, the cumulative value of the supplied oil amount is sequentially obtained from the time when the hydraulic pressure is started to be supplied to the engagement (low speed stage) side frictional engagement element, and the cumulative value is a predetermined discriminant value. After reaching, the release side frictional engagement element is completely released, and the engagement side frictional engagement element is completely engaged.

[0004]

When the cumulative value of the amount of oil supplied to the engagement side frictional engagement element reaches the predetermined determination value,
This means that the engagement side frictional engagement element has completed an ineffective stroke (piston stroke to bring it to a state immediately before it has a torque capacity), and this aims at re-grip in an accurate synchronous state. In the one, the change of the input shaft rotation speed during the gear shift is performed only by the feedback control of the release side hydraulic pressure.

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

Therefore, an object of the present invention is to provide a shift control device for an automatic transmission, which performs torque reduction control of an engine together with feedback control of the hydraulic pressure on the release side, thereby solving the above problems. .

[0007]

According to a first aspect of the present invention, the input rotation is input from an engine output shaft and the input rotation is changed by switching a transmission path by disconnecting and contacting a plurality of friction engagement elements, An automatic transmission mechanism for outputting the changed rotation to the wheels and a hydraulic servo (9, 10) for disconnecting / contacting the friction engagement elements are provided, and power is transmitted from the engine output shaft to the wheels. An input speed detection for detecting the input speed in an automatic transmission, in which one of the friction engagement elements is released and the other one is engaged to perform a downshift shift in a power-on state. 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 operating means (8) so as to achieve the following.

Further, according to the present invention of claim 1, the down state (T _ca ) of the torque control amount (T _C ) by the engine control means (1b) is changed to the change rate (dN) of the input rotational speed during shifting. It is set based on _TS ).

According to a second aspect of the present invention, the torque reduction by the engine control means is controlled by a predetermined value (N) in which an input shaft rotational speed change amount (ΔN) from the start of shift control is preset.
_According to another aspect of the present invention, there is provided a shift control device for an automatic transmission according to claim 1, which starts at a point ( _TS ).

The present invention according to claim 3 is synchronized with the fact that the oil pressure (P _B ) to the engagement side frictional engagement element hydraulic servo starts to rise toward engagement (dP _B > 0). 3. 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 fourth aspect of the present invention, the engine according to the sweep gradient (dP _B ) in which the hydraulic pressure (P _B ) to the hydraulic servo for the engagement side frictional engagement element rises toward engagement. Return gradient from torque down by control means (T _cb )
The shift control device for an automatic transmission according to any one of claims 1 to 3, wherein:

[Operation] Based on the above configuration, power-on
In the downshift, the disengagement hydraulic pressure (P _A) is input speed change amount (.DELTA.N) a predetermined value (N _S) to become the feedback control (FB) is started, the input rotational speed change rate (dN _S) The pressure adjusting 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.
When the value reaches, the engine control means (1b) starts the engine torque down control.

[0013] The torque-down, for example, the input rotational speed change rate (acceleration dN _TS) by reduction amount (T _ca) is calculated, swept down a gradient such that the reduction amount when the shift is complete, the The torque reduction is stopped when the engagement side hydraulic pressure (P _B ) starts sweeping up toward the target value (P _TB ), for example. Then, for example, the return amount (T _cb ) is calculated on the basis of the sweep gradient (dP _B ) of the engagement side hydraulic pressure, and the torque control is performed at a gradient such that the torque control amount (T _c ) becomes 0 when the shift control is completed. The control amount sweeps up.

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

[0015]

According to the first aspect of the present invention, since the torque down control is performed during the feedback control of the hydraulic pressure on the releasing side, the hydraulic pressure on the releasing side can be lowered, and the friction material of the friction engaging element on the releasing side. It is possible to improve the durability of the engine and reduce the control amount of the release side hydraulic pressure in the feedback control to prevent the occurrence of engine blowing due to the hydraulic response delay or the like.

Further, according to the present invention as set forth in claim 1, since the torque down state is set based on the rate of change in the rotational speed of the input rotational speed, it is moderated by a rapid rotational speed change such as kick down and a slight depression of the throttle pedal. Even if the input rotation speed gradient such as a large rotation change is different, a proper torque down state can be always set, and engine blowing and output torque fluctuation can be prevented.

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

According to the third aspect of the present invention, the stop of the torque down is synchronized with the start of the increase of the oil pressure on the engagement side, so that the two-stage shock is generated as in the case of separately controlling the oil pressure on the engagement side and the torque down. It is possible to prevent the occurrence and to smoothly increase the output shaft torque.

According to the fourth aspect of the present invention, since the return gradient from the torque down is set according to the sweep gradient of the hydraulic pressure on the engagement side, the sweep gradient is not affected and the response is always accurate. It is possible to change gears and surely prevent engine blowing.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present automatic transmission has a large number of friction engagement elements such as clutches and brakes, and an automatic transmission in which the transmission path of a planetary gear is selected by appropriately connecting and disconnecting these friction engagement elements. A mechanism (not shown) is provided, the input shaft of the automatic transmission is connected to the engine output shaft via a torque converter, and the output shaft is connected to the drive wheels.

FIG. 1 is a block diagram showing electric system control. Reference numeral 1 is a control unit (ECU) composed of a microcomputer, which is an engine rotation sensor 2 and a throttle opening for detecting an accelerator pedal depression amount of a driver. Sensor 3, a sensor 4 for detecting the actual throttle opening of the engine, a sensor 5 for detecting the input shaft speed (= turbine speed) of the transmission (automatic transmission mechanism),
Signals from a vehicle speed (= automatic transmission output shaft speed) sensor 6 and an oil temperature sensor 7 are input, and an electronic throttle system (engine operating means) 8 for controlling the engine throttle and a linear solenoid of a hydraulic circuit. Outputs to valves (pressure adjusting means) SLS and SLU. The control unit 1 uses the linear solenoid valve SLS or SL.
A hydraulic pressure control means 1a for transmitting a pressure adjusting signal to U and an engine control means 1b for transmitting a throttle opening command to the electronic throttle system 8 are provided, and the hydraulic pressure control means 1a outputs the release side hydraulic pressure to the input rotation 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, and the engine control means 1b controls so that the engine torque is reduced to a predetermined value during the feedback control as described later. To do.

FIG. 2 is a diagram showing the outline of the hydraulic circuit.
A plurality of friction engagement elements having the two linear solenoid valves SLS and SLU and switching the transmission path of the planetary gear unit of the automatic transmission mechanism to achieve, for example, the fourth or fifth forward speed and the first reverse speed. Plural hydraulic servos 9 and 1 for connecting and disconnecting (clutch and brake).
Has 0. In addition, the linear solenoid valve S
Solenoid modulator pressure is supplied to the input ports a ₁ and a ₂ of the LS and SLU, and the control oil pressures from the output ports b ₁ and b _{2 of} these linear solenoid valves are controlled in the control oil chambers of the pressure control valves 11 and 12, respectively. It is supplied to 11a and 12a. The line pressures of the pressure control valves 11 and 12 are supplied to the input ports 11b and 12b, respectively, and the pressure regulation from the output ports 11c and 12c regulated by the control oil pressure shifts the shift valves 13 and 15, respectively. It is appropriately supplied to each hydraulic servo 9, 10.

This hydraulic circuit is for showing the basic concept, and the hydraulic servos 9 and 10 and the shift valves 13 and 15 are shown symbolically, and actually,
A large number of hydraulic servos are provided corresponding to the automatic transmission mechanism, and a large 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 fitted in a cylinder 16 in an oil-tight manner by an oil seal 17, and the piston 19 acts on the hydraulic chamber 20. Based on the pressure-adjusted hydraulic pressure from (3), it moves against the return spring 21 and brings the outer friction plate 22 and the inner friction member 23 into contact with each other. Although the friction plate and the friction material are shown as a clutch, it goes without saying that the same applies to a brake.

Next, the shift control device according to the present invention will be described with reference to FIG. 3. First, based on FIG. 4, the release side hydraulic pressure P _A at the time of downshifting by the clutch grip change shift at power-on will be described.

When the driver feels that the torque is insufficient and depresses the accelerator pedal while the vehicle is traveling, the control unit 1 determines a downshift from the map based on signals from the throttle opening sensor 3 and the vehicle speed sensor 6. . Then, after a predetermined delay time from the shift determination, timing is started and shift control is started (S1). At the start time (t = 0),
_A control signal in which the disengagement hydraulic pressure P _A becomes the engagement pressure P _W is output to the linear solenoid valve SLS (or SLU), and the disengagement side frictional engagement element is in an engaged state (S2). And
The disengagement torque T _A is calculated by the function of the input torque T _t (S2). As for the input torque T _t , the engine torque is obtained from the map based on the throttle opening and the engine speed, the speed ratio is calculated from the input / output speed of the torque converter, and the torque ratio is found from the map based on the speed ratio.
It is obtained by multiplying the engine torque by the above torque ratio. Further, the disengagement side torque T _A is obtained by the torque sharing rate or the like being involved in the input torque.

Further, the target hydraulic pressure P _TA on the release side is calculated based on the release side torque T _A (S4). That is, the effective radius of the disengagement side friction engagement element x piston area x number of sheets x friction coefficient is defined as A, and disengagement side piston stroke pressure (return spring pressure)
Let B be the release hydraulic pressure P _A , [P _A = (T _A /
It is calculated by A) + B]. Then, the release side hydraulic pressure P _A
Sweeps down from the engagement pressure P _W toward the target hydraulic pressure P _TA (S5). When the disengagement hydraulic pressure P _A reaches the target hydraulic pressure P _TA (S6), the predetermined gradient [(P _TA
-P _W ) / t _TA ] is stopped and the target hydraulic pressure P _TA is maintained (S7).

Next, when the change amount ΔN of the input rotation speed N _T by the input shaft rotation speed sensor 5 from the start of the gear shift exceeds the preset rotation speed N _S (S8), the feedback control FB is started (S9). ). The feedback control is
The release side hydraulic pressure P _A is regulated so that the input rotation speed change rate dN _S becomes a constant target value. Then, in the feedback control, a predetermined time t _SE for performing the piston stroke control of the engagement-side hydraulic pressure (control of moving the piston until just before the friction material comes into contact with and has a torque capacity), which will be described later, elapses (S10). ), And continues until the engagement side oil pressure P _B reaches a target oil pressure P _TB which will be described later (S11). When the feedback control is completed, the release side hydraulic pressure P _A
Is swept down at a predetermined gradient δP _FA (S12), the sweep down is continued until the hydraulic pressure is drained (S13), and the control of the disengagement hydraulic pressure is completed.

On the other hand, as shown in the flow chart of FIG. 5, the engagement side hydraulic pressure P _B is set to a predetermined pressure P _S1 at the same time when the shift control is started (S1) and at the same time. A signal is output to the linear solenoid valve SLS (or SLU) (S21), and the predetermined pressure P _S1 is held 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 materials 22 and 23 come into contact (fast fill pressure). When the predetermined time t _SA has elapsed, the engagement-side hydraulic pressure P _B has a predetermined gradient [(P _S1 −P _S2 ) / t.
_SB ] to sweep down (S23), and when the engagement side hydraulic pressure P _B reaches the predetermined low pressure P _S2 (S24), the sweep down is stopped and held at 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 rotational change of the input shaft, and the predetermined low pressure P _S2 is held until the time t reaches a predetermined time t _SE (piston). Stroke control) (S26).

Next, the disengagement side torque share T _B is calculated by a function based on the input torque T _t and the disengagement side oil pressure P _A (S27). Further, the engagement side oil pressure P _TB immediately before the start of the rotation change of the input rotation speed N _T is calculated based on the release side torque share T _B (S28). Then, based on the engagement hydraulic pressure P _TB, predetermined gradient is calculated by a preset time _{t TB [(P TB -P S2} ) / t TB], engagement side hydraulic based on the gradient is swept up (S29). By the sweep-up, the engagement torque increases, and the hydraulic pressure rises to the state immediately before the start of the change in the input rotational speed, that is, the calculated target engagement hydraulic pressure P _TB (S30).

By the sweep up, when the engagement side oil pressure P _B reaches the target engagement oil pressure P _TB , it is predicted that the inertia phase in which the rotational change of the input shaft rotation speed is started is completed. That is, N ₁ is the input shaft speed at the start of gear shifting,
Let g _{i + 1 be the} gear ratio before shifting, g _{i be the} gear ratio after shifting, and N _{TE be the} amount of change in rotation (ΔN) at the end of shifting, then ΔN = N _TE = N ₁ (g _{i + 1} −g) , The gear shift is completed.

Then, at this point, the clocking time t _F is set (S31), and this state substantially corresponds to the state where the inertia phase is completed. Furthermore, a relatively sudden change in hydraulic pressure δP _FB
Is set, the hydraulic pressure is rapidly swept up due to the change in the hydraulic pressure (S32), and the predetermined time t _FB set to a time sufficient to rise to the engagement pressure has elapsed from the time measurement time t _F. In the 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 speed N _{T is} controlled by the feedback control (S9) of the disengagement side frictional engagement element.
Rises at a constant gradient, and when the variation ΔN from the start of the control of the input speed reaches a preset predetermined value N _TS , the engine torque down control is activated (S41). If the timing of torque down is always constant, the amount of heat generated by the disengagement side frictional engagement element also increases when the rotation speed at the start of gear shifting is large, that is, when the amount of rotation change during gear shifting is large. If there is a delay, the durability of the friction material may be impaired. However, in this engine torque control, the start point of the torque reduction is the input speed N _T (ΔN = 0) at the start of the shift control as described above. Since it is set based on (ΔN ≧ N _TS ), it is possible to prevent the durability of the disengagement side frictional engagement element from decreasing from high vehicle speed to low vehicle speed.

Then, the rate of change of the input rotational speed at the predetermined value N _{TS, that} is, the acceleration dN _TS is calculated, and the torque reduction amount T _ca is calculated based on the rate of change by the direct proportional function shown in FIG. 7 (a) ( S42). Then, after setting the control amount T _c of the engine torque to 0 (S43),
The control amount is controlled. When the torque reduction amount is set based on the input rotation speed ΔN, the reduction amount is always constant even when the increase gradient of the rotation speed is different, and when the rotation gradient is tight like kick down, engine blowing occurs, Although when the rotation gradient is loose resulting in a change in the output torque T _O, since setting the reduction amount by the rotation change rate dN _TS as described above,
It is possible to always set the optimum reduction amount regardless of the rotation gradient to prevent engine blowing and output torque fluctuation.

The torque control amount T _c is the torque reduction amount T _ca when the shift is completed.
If the input rotation speed (change amount) from the start of gear shifting is ΔN, the torque control amount T _c
Sweeps down with T _c = −T _ca × (ΔN−N _TS / N _TE −N _TS ) (S44). In the sweep down, whether the engagement side oil pressure P _B changes in the upward direction, that is, the change rate dP _{B of the} oil pressure becomes positive (S45), or the input rotation speed change amount ΔN is equal to the input rotation speed N after shifting. Continue until _TE (S46). At this time, 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 , so that the engagement-side oil pressure is increased and the torque-down is stopped at different timings. It can prevent the occurrence of shock.

When dP _B > 0 or ΔN ≧ N _TE , the rate of change dP _B of the engagement side hydraulic pressure P _B , that is, the target value P
_From the sweep gradient toward _TB , the return amount T _cb is calculated based on the inverse proportional function as shown in FIG. 7 (b) (S47).
Then, the torque control amount T _c obtained by multiplying the return amount T _cb by the ratio of the engagement side oil pressure P _B to the target oil pressure P _TB .
Then, the torque control amount [T _ca ] interrupted in step S45 or S46 is swept up (S48). [T _ca ] in step S48
Is the torque control amount at which the sweep down in step S44 is interrupted, and often does not match the reduction T _ca calculated in step S42. The sweep down is ended when the torque control amount T _c exceeds 0 (S49), and this point is generally the point where the engagement side hydraulic pressure P _B reaches the target value P _TB , that is, the inertia phase ends. The engine torque control ends when the input speed N _T reaches the speed N _TE after shifting.

At this time, if the return gradient of the torque control amount is constant, the rise of the torque is delayed with respect to the torque capacity of the engagement side frictional engagement element when the sweep gradient of the engagement side hydraulic pressure is large. Response deteriorates, and if the sweep gradient of the engagement-side hydraulic pressure is small, the engine rises because the torque rises faster with respect to the torque capacity. By setting according to the sweep gradient, it is possible to reliably prevent the deterioration of the response and the engine blowing.

Therefore, the torque reduction control of the engine is performed together with the feedback control of the release side oil pressure P _A described above, so that the release side oil pressure P _A is kept lower than that of the conventional technique (P _A ′). Therefore, the durability of the friction material of the friction engagement element can be improved by that amount, and the engine blowing or the like due to the hydraulic response delay can be prevented.

[Brief description of drawings]

FIG. 1 is an electrical 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 an embodiment of the present invention.

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

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

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

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

[Explanation of symbols]

1 Control Unit 1a Hydraulic Pressure Control Means 1b Engine Control Means 5 Input Speed Detection Means (Sensor) 8 Engine Operating Means (Electronic Throttle System) 9, 10 Hydraulic Servo N _T Input Speed N _TS Predetermined Value dN _TS Input Speed Change Rate P _A Release side hydraulic pressure P _B Engagement side hydraulic pressure dP _B Sweep gradient T _C Engine torque (control value) T _ca Down state (reduction amount) T _cb Return state (return amount)

Front page continuation (51) Int.Cl. ⁷ Identification symbol FI // F16H 59:42 F16H 59:42 (72) Inventor Masao Saito 10 Takane, Fujii-cho, Anjo City, Aichi Prefecture Aisin AW Co., Ltd. (72) Inventor Takayuki Kubo 10 Takane, Fujii-cho, Anjo City, Aichi Prefecture Aisin AW Co., Ltd. (56) References JP-A-9-72409 (JP, A) JP-A-9-68267 (JP, A) JP 63-254256 (JP, A) JP 63-266259 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60K 41/06 F02D 29/00 F16H 61 / 00

Claims (4)

(57) [Claims] 1. Input from an engine output shaft,
Transmission of rotation by disconnecting and contacting multiple friction engagement elements
Change the path by switching the route and output the changed rotation to the wheels
Automatic transmission mechanism and disconnection / contact operation of each friction engagement element
Equipped with a hydraulic servo, A power transmission that transmits power from the engine output shaft to wheels.
Release one of the friction engagement elements in the
Automatic change that engages the other one and shifts downshift
In speed machines, Input rotation speed detection means for detecting the input rotation speed, Pressure adjusting means for adjusting the hydraulic pressure communicating with the hydraulic servo, Engine operating means for operating the engine torque, The release side frictional engagement element based on the change of the input rotation speed
Feedback control to control the hydraulic pressure to the hydraulic servo
Hydraulic control means including During the feedback control, the change of the input speed
Controls the engine operating means so that the conversion becomes a predetermined characteristic
Engine control means forEquipped with The amount of torque control by the engine control means
The idle state according to the rate of change of input speed during shifting
To do A shift control device for an automatic transmission characterized by the above. 2. The shift of the automatic transmission according to claim 1, wherein the torque reduction by the engine control means is started at a point where an amount of change in the input shaft speed from the start of the shift control reaches a predetermined value set in advance. Control device. 3. The hydraulic pressure to the engaging-side frictional engagement element hydraulic servo is synchronized with the start of rising toward engagement,
The shift control device for an automatic transmission according to claim 1, wherein control of the torque down direction by the engine control means is stopped. 4. The hydraulic pressure to the engagement side frictional engagement element hydraulic servo increases in response to a sweep gradient increasing toward engagement.
The shift control device for an automatic transmission according to claim 1, wherein the engine control means sets a return gradient from the torque reduction.