JP3405113B2 - 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 member in a power-off state where power is not transmitted from an engine to a wheel. The present invention relates to a shift control device for downshifting by changing the grip of a coupling element and an engagement side frictional engagement element, that is, a so-called clutch-to-clutch shift.

[0002]

2. Description of the Related Art Generally, downshifting by clutch-to-clutch in a power-off state is performed by operating a manual lever, for example, from D range to S or L range, and is used when engine braking is required. .

Conventionally, as shown in FIG. 1, when the accelerator pedal is released (power off), the release (high speed) side hydraulic pressure P _A is reduced to release the release (high speed) side friction engagement element. Since the transmission relationship between the engine and the wheels is broken, the input speed N _T decreases due to the power off state. From this state, the engagement (low speed) side oil pressure P _B rises toward the engagement pressure after the servo is started (the operation to close the clearance of the clutch and immediately before the torque capacity is generated), and the engagement side frictional engagement is performed. By increasing the torque capacity of the element, the input speed N _T is increased to synchronize with the low speed stage. At this time, as described above, until the disengagement side frictional engagement element is disengaged and the engagement side frictional engagement element starts to engage, the engine brake does not operate and the driver does not operate manually. I feel the air running though I request engine braking.

Further, as described above, the input rotation speed N _T once decreases in the neutral state, and the input rotation speed N _T is changed to the low speed stage by the engagement start of the engagement side frictional engagement element from the lowered condition. Since the gear ratio increases toward the gear ratio, it takes time to shift, and the engine braking force temporarily increases to cause a shift shock.

With regard to the downshift shifting in the power-off state, the one shown in Japanese Patent Laid-Open No. 5-31262 (the former) and the one shown in Japanese Patent Laid-Open No. 5-229368 (the latter) have been proposed.

When the former detects that the input (turbine) rotation speed has decreased by a predetermined amount from the rotation speed before the gear shift, feedback control of the hydraulic pressure on the release side is performed to suppress the decrease in the input rotation speed, and thus during downshifting. It is intended to prevent the feeling of free running.

In the latter case, in the power-off downshift, during the period in which the disengagement (high-speed) side friction engagement element begins to slip until the post-engagement (low-speed) side friction engagement element is completely engaged. The engine is controlled so that the engine is blown up, and thereby, the shift shock at the time of downshift and the shift time are shortened.

[0008]

However, in the former case, since the decrease of the input rotational speed is suppressed only by the feedback control of the hydraulic pressure on the release side, the frictional engagement element on the release side considerably copes with the above suppression of the decrease. Since it is necessary to maintain the torque capacity, it is extremely difficult to re-grip the engagement side frictional engagement element, and depending on the timing, the input rotation speed may drop or the tie-up may occur to cause a shift shock. However, there is a possibility that the durability of the friction material of the disengagement side frictional engagement element may be reduced.

In the latter case, regardless of the power-off state, the input speed N _T is high due to the engine blowing and is in the power-on state as shown by the one-dot chain line in FIG. It gives a feeling.

Therefore, an object of the present invention is to provide a shift control device for an automatic transmission, which solves the above-mentioned problems by controlling both the releasing hydraulic pressure and the engine torque.

[0011]

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 that outputs the changed rotation to the wheels and a hydraulic servo (9, 10) that disconnects and makes contact with each of the friction engagement elements are provided, and power is not 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 disengaged and the other one is engaged for downshift gear shifting in a power-off state. Pressure adjusting means (SLU or SL) for adjusting the hydraulic pressure (P _A ) communicating with the means (5) and the release side frictional engagement element hydraulic servo ( 9 or 10).
S), the engine operating means (8) for operating the engine torque, and the first input speed before the downshift.
Target value (N _TS ) of the input rotation speed detection means (5)
Engine control means (1b) for controlling the engine operating means (8) so that the actual input speed (N _T ) based on Eq.
Input target speed lower than _TS ) by a predetermined amount to the second target value (N _TR )
The pressure adjusting means (SLU or SL) is set so that the actual input rotation speed (N _T ) does not fall below the second target value.
And a release hydraulic pressure control means (1a) for controlling S), and a shift control device for an automatic transmission.

According to the second aspect of the present invention, in the release hydraulic pressure control means (1a), the actual input rotation speed (N _T ) based on the input rotation speed detection means (5) is the second target value ( N
Lower than _TR), to control the release side hydraulic pressure (P _A) so that the input rotational speed becomes the second target value when said actual, the engine control means (1b), the actual input revolution speed ( N
_{When T} ) is higher than the second target value (N _TR ), the engine torque (T _C ) is controlled so that the actual input rotation speed becomes the first target value (N _TS ). The shift control device for an automatic transmission according to claim 1.

According to a third aspect of the present invention, the engine control means (1b) has a negative sum of the engine torque control value (T _C ) and the engine torque (T _E ) during the downshift. The shift control device for an automatic transmission according to claim 1 or 2, wherein the engine torque is controlled within a range.

[0014] Incidentally, the second target value (N _TR) and the difference is, the minimum amount of control of the release pressure by the releasing pressure control means (1a) of the first target value (N _TS) (dP _A; S4
It is preferable that the value is set to a value larger than the rotation change amount of the input rotation speed (N _T ) that occurs in 2).

[Operation] When the input speed (N _T ) is lower than the second target value (N _TR ) when downshifting in the power-off state, such as manual downshifting, based on the above configuration. , Release hydraulic pressure (P
_A ) indicates that the input rotation speed (N _T ) is the second target value (N _TR ).
Is feedback controlled so that Further, when the input speed (N _T ) is higher than the second target value (N _TR ), the engine torque (T _C ) is feedback-controlled so that the input speed becomes the first target value (N _TS ). To be done. In this case, the engine torque is always controlled within the scope which is in non-drive state (state in which the power transmission from the wheel to the engine side), if that exceeds it, so that the release side hydraulic pressure (P _A) assists Feedback control.

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

[0017]

According to the first aspect of the present invention, it is possible to prevent the gear ratio from becoming lower than the gear ratio before shifting due to the engine torque and the hydraulic pressure on the releasing side, and at that time, the hydraulic pressure on the releasing side is set to be low, whereby Medium, the release side frictional engagement element is always kept in a sliding state, and the drop in rotation is controlled by the engine torque, so the driver does not feel idle and the tie-up amount is reduced. Therefore, it is possible to prevent gear shift shock and also prevent deterioration of durability of the release side friction member.

According to the second aspect of the present invention, when the actual input speed is higher than the second target value, the engine torque is controlled by the engine control means so as to reach the first target value. Unlike the case where the hydraulic pressure control and the engine torque control are performed so as to achieve the first target value, hunting does not occur between them, and the control reliability can be improved.

According to the third aspect of the present invention, the control range of the engine torque is set so that the gear shift is always performed in the non-driving state, so that it is possible to prevent the feeling of idling due to the driving state during the gear shifting. It is possible to obtain a good shift feeling.

[0020] Incidentally, when the actual input speed is lower than the second target value, performs the hydraulic control of the disengagement side as said actual Sai value becomes the second target value, the hydraulic control of the minimum When the difference between the first target value and the second target value is small with respect to the rotation change amount that can be caused, the actual value is equal to or larger than the first target value by performing hydraulic control, that is, the release side The hydraulic pressure rises too much, and a shift shock due to a drop in rotation or tie-up occurs depending on the timing of grip change with the engagement side, but the first target value is higher than the rotational change amount that can be caused by the minimum control amount of hydraulic pressure. Between the second target value and
By setting the (difference) to be large, it is possible to prevent the hydraulic pressure control from becoming larger than the first target value, and it is possible to prevent a rotation drop or a tie-up due to a grip change with the engagement side.

[0021]

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. 2 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),
Various 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. Valve S
Output to LS and SLU. The control unit 1 includes a release hydraulic pressure control means 1a for transmitting a pressure adjusting signal to the linear solenoid valve SLS or SLU and an engine control means 1b for transmitting a throttle opening command to the electronic throttle system 8, and engine control is performed. The means 1b sets the first target value N _TS of the input speed before the downshift gear shift (at the time of starting the shift control), and the actual input speed N _T based on the input shaft speed sensor 5 is the first target value. The engine torque T _C is controlled so as to maintain the above, and the disengagement hydraulic pressure control means 1a sets a second target value at an input rotational speed lower than the first target value by a predetermined amount, and the actual input rotational speed is The disengagement hydraulic pressure P _A is controlled so as not to be less than or equal to the second target value.

FIG. 3 is a diagram showing an 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. 4. First, the release hydraulic pressure P _A at the time of downshifting by clutch-to-clutch shift at power-off will be described with reference to FIG.

When the accelerator pedal is released while the vehicle is running at high speed (throttle opening θ = 0) and the shift lever is downshifted from the D range to the S or L range, a predetermined delay time elapses from the shift determination. Timing is started (S1). At the start time point (t = 0), a control signal for changing the disengagement hydraulic pressure P _A to the engagement pressure P _W is output to the linear solenoid valve SLS (or SLU) so that the disengagement side frictional engagement element engages. It is in a state of Then, the disengagement side 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. At this time, since the throttle opening is 0, the input torque T _t is small, and the torque distribution ratio to the input torque or the like is required the release side torque T _A is involved, the disengagement side torque T _A Is small.

Further, the target hydraulic pressure P _TA on the release side is calculated based on the release side torque T _A (S3). 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
At the same time as the start of the shift control, the target hydraulic pressure P _TA rapidly decreases to a low pressure.

Then, feedback control is immediately performed (S4). The feedback control will be described later with reference to the engine torque feedback control based on FIG. 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 with and has a torque capacity), which will be described later, elapses (S5), And it continues until the engagement side oil pressure P _B reaches a target oil pressure P _TB which will be described later (S6). Then, when the feedback control is completed, the disengagement hydraulic pressure P _A is swept down at a predetermined gradient δP _FA (S7), and the sweep down is continued until the hydraulic pressure is drained (S8). Control ends.

On the other hand, as shown in the flowchart of FIG. 6, the engagement side hydraulic pressure P _B is set to a predetermined pressure P _S1 at the same time as the shift control is started (S1) and at the same time. A signal is output to the linear solenoid valve SLS (or SLU) (S11), and the predetermined pressure P _S1 is held for a predetermined time t _SA (S12). 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 with each other.
When the predetermined time t _SA has elapsed, the engagement-side hydraulic pressure P _B is swept down at a predetermined gradient [(P _S1 −P _S2 ) / t _SB ] (S13), and the engagement-side hydraulic pressure P _B is reduced to the predetermined low pressure P _S2. When it becomes (S14), the sweep down is stopped, and the predetermined low pressure P _S2 is maintained (S15). 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 rotation change of the input shaft, and the predetermined low pressure P _S2 is measured at time t.
Is held until a predetermined time t _{SE has} elapsed (piston stroke control) (S16). 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 (S17). Further, based on the release side torque share T _B , the engagement side oil pressure P _TB immediately before the start of the rotation change of the input speed N _T (just before the start of the inertia phase) is calculated (S18). 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 (S19). By the sweep-up, the engagement torque increases, and the hydraulic pressure rises to the state immediately before the start of the change of the input rotational speed, that is, the calculated target engagement hydraulic pressure P _TB (S20).

It is predicted that the sweep-up has reached the target engagement oil pressure P _TB , that is, it is predicted that the inertia phase in which the rotational change of the input shaft rotational speed is started is entered, and the rotational change amount ΔN until the completion of the downshift is completed. Α ₁ [%] of, for example, 7
It is continued until 0 [%] (S21). That is, _letting N _{TS be} the input shaft rotation speed at the start of gear shifting, ΔN being the amount of rotation change, g _{i + 1} being the gear ratio before gear shifting, and g _i being the gear ratio after gear shifting, [(ΔN ×
100) / N _TS (g _{i + 1} −g _i )] becomes α ₁ [%].

Further, when α ₁ [%] of the rotation change amount is exceeded, different hydraulic pressure change δP _LB is set by the feedback control based on the smooth input shaft rotation speed change amount ΔN.
Sweep up according to the gradient of δP _LB (S2
2). The δP _LB has a gentler gradient than the increase in the hydraulic pressure to the target engagement hydraulic pressure P _TB , and the sweep-up is α ₂ [%] of the rotational speed change amount up to near the completion of the shift, for example, 90%.
It is continued to [%] (S23).

Then, when α ₂ [%] of the rotational speed change amount is reached, the clocking time t _F is set (S24), and this state substantially corresponds to the state where the inertia phase has ended. Further, a relatively sudden change in hydraulic pressure δP _FB is set, and the hydraulic pressure is swept up rapidly due to the change in hydraulic pressure (S2
5) Then, when the predetermined time t _FB set to a time sufficient to rise to the engagement pressure elapses from the measured time t _F (S26), the hydraulic control on the engagement side is completed.

Next, the engine torque control will be described with reference to FIG. The engine is idling based on the throttle opening being 0, but when the shift control is started (t = 0), the engine speed N _T becomes the first target speed N _TS. The torque T _C is feedback-controlled (S31). The feedback control is performed together with the feedback control of the disengagement hydraulic pressure P _A , which will be described later with reference to FIG. Then, the feedback control is continued for the piston stroke control time t _{SE of} the engagement-side hydraulic pressure P _B described above (S32). After the lapse of the predetermined time t _SE , the engine control torque T _C is swept down at a predetermined gradient δT _C until the torque becomes 0 (S33, S34).

Next, referring to FIG. 8, step S4
The feedback control shown in S31 will be described. First, the actual input rotation speed N _T based on the input shaft rotation sensor 5 is set to be slightly lower than the input rotation speed N _TS at the start of the shift control, and the (second) target rotation speed N _{TR of} the release side hydraulic pressure is set. (S41). Actual input speed N _T
Is lower than the preset second target speed N _TR (N _T ≦ N _TR ), the release side hydraulic pressure P _A is controlled to be high (S42). That is, as shown in FIG. 9 (a), the variation dP _A the release side hydraulic pressure increases in proportion to the difference between the input rotational speed N _T and the target engine speed N _TR (N _TR -N _T) ,
Therefore, the disengagement hydraulic pressure P _A is feedback-controlled so that the input speed N _T becomes the target speed N _TR . As a result, the disengagement side frictional engagement element is not completely disengaged, is held in the slip state, is prevented from shifting to the neutral side, and the engine brake based on the gear ratio g _{i + 1} before the shift is operated.

On the other hand, when the input speed is higher than the second target speed (N _T > N _TR ), the actual input speed N _T
Is the input speed at the start of gear shift control (first target speed)
It is compared with N _TS (S43). If the input rotation speed is lower than the rotation speed at the start of gear shift (N _T ≤N _TS ), the engine torque T _C is controlled to be high (S44).
That is, as shown in FIG. 9 (b), the engine control torque change amount dT _C is feedback controlled so as to be proportional to the difference between the shift start time of rotation speed N _TS as the input rotational speed N _T (N _TS -N _T) To be done. At this time, based on the manual downshift, the original engine torque T _E is in the negative torque state (T _E <0), and the control torque T _C is generally in the positive torque state (T _C
> 0), it is judged whether the engine output torque (T _E + T _C ) obtained by combining these two torques is positive or negative, and the engine torque control is negative, that is, a non-driving state in which power is transmitted from the wheels to the engine side. It is performed only in the range of 1, and it is possible to prevent the feeling of idling due to the driving state during the gear shift. Further, when the engine output torque is positive, that is, when the engine is in a driving state in which torque is transmitted to the wheel side, the release side hydraulic pressure P _A is further increased by the predetermined change amount dP _A.
Feedback control is performed so as to increase at (S4
6). That is, when the engine is in the non-driving state (engine braking state) only by the engine torque control, the feedback control of the hydraulic pressure on the release side is not further added. Hydraulic pressure control is assisted.

In step S43, if the input rotation speed is higher than the input rotation speed at the start of gear shifting ( _NT >
N _TS ) and the engine torque T _C are feedback-controlled so as to be low (S47).

As a result, when the actual input speed N _T is higher than the second target speed N _TR , the engine torque control alone is performed so that the input speed N _T becomes the shift start speed N _TS. Alternatively, feedback control is performed by being assisted by the hydraulic pressure control on the release side. Therefore, the disengagement side friction engagement element is put in the slip state, and the drop of the input rotational speed is controlled by the engine torque control so as not to give the driver a feeling of idling, and the disengagement side and engagement side friction engagement elements are not affected. By reducing the tie-up amount of the coupling element, it is possible to reduce shift shock and prevent deterioration of the durability of the disengagement side frictional engagement element.

[Brief description of drawings]

FIG. 1 is a time chart showing a downshift shift at the time of power off according to a conventional technique.

FIG. 2 is an electric block diagram according to the present invention.

FIG. 3 is a diagram showing an outline of a hydraulic circuit according to the present invention.

FIG. 4 is a time chart according to an embodiment of the present invention.

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

FIG. 6 is a flowchart showing hydraulic pressure control on the engagement side.

FIG. 7 is a flowchart showing the engine torque control.

FIG. 8 is a flowchart showing feedback control of release hydraulic pressure and engine torque.

FIG. 9 (a) is a diagram showing a control amount of the hydraulic pressure on the release side, and FIG.
FIG. 4 is a diagram showing a control amount of engine torque.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Control unit 1a Release hydraulic pressure control means 1b Engine control means 5 Input rotation speed detection means (sensor) 8 Engine operation means (electronic throttle system) 9, 10 Hydraulic servo _NT Input rotation speed N _TS First target value (before shifting) Input speed) N _TR Second target value P _A Release side hydraulic pressure T _C Engine torque (control value)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI // F16H 59:42 F16H 59:42 (72) Inventor Masaharu 10 Takane, Fujii-cho, Anjo-shi, Aichi Aisin AW Co., Ltd. (72) Inventor Takayuki Kubo 10 Takane, Fujii-cho, Anjo City, Aichi Aisin AW Co., Ltd. (56) Reference JP-A-8-270780 (JP, A) JP-A-5-231525 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60K 41/00-41/28 F02D 29/00 F16H 61/08

Claims (3)

(57) [Claims] 1. An automatic transmission mechanism for inputting the input rotation from an engine output shaft, switching the transmission path by disconnecting and contacting a plurality of friction engagement elements to shift the speed, and outputting the changed rotation to wheels. And a hydraulic servo for actuating / disconnecting each of the friction engagement elements to release one of the friction engagement elements in a power-off state in which power is not transmitted from the engine output shaft to the wheels. In an automatic transmission, which is configured to engage another one to perform a downshift gearshift, an input rotation speed detecting means for detecting the input rotation speed, and a hydraulic pressure communicating with the hydraulic servo for the disengagement side frictional engagement element are provided. The pressure adjusting means for adjusting the pressure, the engine operating means for operating the engine torque, the input rotational speed before the downshift gear shift is set as a first target value, and the actual input rotational speed based on the input rotational speed detecting means is the first input value. One An engine control means for controlling the engine operating means so as to maintain a standard value, an input rotational speed lower by a predetermined amount than the first target value as a second target value, and the actual input rotational speed is the second And a release hydraulic pressure control means for controlling the pressure adjusting means so as not to be less than or equal to the target value of the shift control apparatus for an automatic transmission. 2. The release hydraulic pressure control means sets the actual input rotation speed to the second target value when the actual input rotation speed based on the input rotation speed detection means is lower than the second target value. When the actual input speed is higher than the second target value, the engine control means controls the actual input speed to be the first target value. The shift control device for an automatic transmission according to claim 1, wherein the engine torque is controlled. 3. The engine control means controls the engine torque within a range in which the sum of the control value of the engine torque and the engine torque during the downshift is negative. 2. A shift control device for an automatic transmission as described in 2.