JP2842027B2 - 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.

[0002]

2. Description of the Related Art Automatic transmissions (A / T) are known from, for example, Showa 62
As described in the "RE4R01A Automatic Transmission Maintenance Manual" issued by Nissan Motor Co., Ltd. in March 2013, it is possible to shift to the corresponding gear by selectively operating various friction elements. In such a shift (multi-stage shift),
For smooth shifting, slip control can be performed on the corresponding frictional elements (band brake B / B, high clutch H / C, etc.) that will be engaged / disengaged to reduce shift shock. it can.

[0003]

However, the present inventor has noticed that there is room for improvement in the above technology from the following aspects. That is, when the slip control is performed at the time of a corresponding shift for all corresponding friction elements such as a band brake and a high clutch,
As a result of ensuring and maintaining good shifting characteristics that all applicable friction elements can withstand the heat generated by the slip control, in this regard, to make these individual friction elements smaller and lighter, Is limited and has a large weight size. On the other hand, in order to reduce the heat load from this point, for example, if the engagement is strongly performed in the engagement control of the friction element which is switched to the engagement during the gear shift, the shock in the gear shift deteriorates accordingly. Further, in terms of shift shocks, in each shift, torque during shifting is separately output by a separate element such as a band brake, a high clutch, etc., so that each shift has a different mode of shift shock. It can be said that it is difficult to make the shift shock consistent.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the above-mentioned object, and it is possible to reduce the heat load on a friction element to be switched at the time of shifting, and to realize an automatic transmission capable of realizing both weight size and shifting shock. To provide a shift control device.

[0005]

According to the present invention, the following shift control device is provided. A shift control device for an automatic transmission that shifts by switching between engagement and disengagement of a friction element.
A control pressure control means that uses the engaged first friction element as a control target friction element; and a friction element other than the first friction element, from a released state before shifting to an engaged state after shifting or before shifting. A plurality of second friction elements that are switched from the engaged state to the released state after shifting, and engagement / release control means for the second friction elements that are engaged or released during shifting. The control pressure control unit is configured to perform a shift by changing at least one of the second frictional elements from release to engagement or from engagement to release by the engagement / release control unit. A transmission torque is controlled so as to control an output torque based on an input torque of the transmission, and a slip is applied to the first friction element so as to absorb a torque fluctuation caused by a shift in switching of the second friction element. Control is a shift control apparatus for an automatic transmission that performs.

[0006]

The shift control device for an automatic transmission according to the present invention shifts by switching the engagement and release of a friction element. The shift control device includes the control pressure control means and the engagement and release control means, and performs both before and after shifting. The control pressure control means using the first friction element, which has not been released but is being fastened, as the friction element to be controlled is at least one of the second friction elements by the engagement / release control means.
At the time of a gear shift in which at least one of the gears is switched from disengagement to engagement or from engagement to disengagement to realize a gear shift, the transmission torque is controlled so as to control the output torque based on the input torque of the transmission during the gear shift. The slip control is performed on the first friction element so as to absorb the torque fluctuation due to the shift of the switching of the friction element. Thereby, the first friction element is slid during the shift to control the torque during the shift, to bear the heat associated with the slip, and to reduce the heat load on the second friction element to be switched during the shift, thereby reducing the second friction element. It is possible to absorb the torque fluctuation due to the shifting of the friction element switching. Because the first friction element is mainly a heat-bearing element,
As the other second friction element, one that generates less heat can be used, it can be made smaller and lighter, and it is possible to achieve both the weight size and the shift shock. It is also easier to be consistent.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In the drawing, reference numeral 10 denotes an engine, and reference numeral 20 denotes a transmission mechanism of an automatic transmission. FIG.
Exemplifies a power transmission train of an automatic transmission to which the present invention is applied, and the power transmission train includes a torque converter 3, a first planetary gear set 4, and a second planetary gear set 5 that transmit rotation from an engine output shaft 1 to an input shaft 2. , The output shaft 6 and various friction elements described later.

The torque converter 3 is driven by an engine output shaft 1 and is also used for driving an oil pump O / P. The pump impeller 3P is fluid-driven by the pump impeller through an internal working fluid. A turbine runner 3T for transmitting and a stator 3S placed on a fixed shaft via a one-way clutch 7 to increase torque to the turbine runner 3T, and a lock-up clutch
A normal lock-up torque converter with 3L added. The torque converter 3 receives the supply of the working fluid from the release chamber 3R, and releases the lock-up clutch 3L and removes the engine power through the pump impeller 3P and the turbine runner 3T while the working fluid is removed from the apply chamber 3A ( In the converter state, the torque is transmitted to the input shaft 2 while increasing the torque. Conversely, while the working fluid is supplied from the application chamber 3A and the working fluid is removed from the release chamber 3R, the lock-up clutch 3L is engaged and the engine power is increased. Is transmitted to the input shaft 2 via the lock-up clutch as it is (in a lock-up state). In the latter lock-up state, the slip of the lock-up torque converter 3 (relative rotation of the pump impeller 3P and the turbine runner 3T) is arbitrarily controlled (slip control) by reducing the working fluid rejection pressure from the release chamber 3R. can do.

The first planetary gear 4 is a sun gear 4S, a ring gear
4R, a normal simple planetary gear set including a pinion 4P meshing with the pinion 4P and a carrier 4C rotatably supporting the pinion 4P, and the second planetary gear set 5 is also a sun gear 5S and a ring gear 5
A simple planetary gear set consisting of R, pinion 5P and carrier 5C.

Next, the various friction elements will be described. The carrier 4C can be appropriately connected to the input shaft 2 via the high clutch H / C, and the sun gear 4S can be appropriately fixed to the input shaft 2 by the reverse clutch R / C in addition to the sun gear 4S. I do. The carrier 4C can be appropriately fixed by a multi-plate low reverse brake LR / B, and also prevents reverse rotation (rotation in the opposite direction to the engine) via a low one-way clutch LO / C. The ring gear 4R is integrally connected to the carrier 5C and is drivingly connected to the output shaft 6, and the sun gear 5S
To the input shaft 2. The ring gear 5R can be appropriately coupled to the carrier 4C via an overrun clutch OR / C, and is correlated with the carrier 4C via a forward one-way clutch FO / C and a low clutch (forward clutch) L / C. The forward one-way clutch FO / C connects the ring gear 5R to the carrier 4C in the reverse rotation direction (the direction opposite to the engine rotation) in a state where the low clutch L / C is connected. In addition, high clutch H / C, reverse clutch R / C, low reverse brake R / B, band brake B /
B, the overrun clutch OR / C and the low clutch L / C are each actuated by the supply of hydraulic pressure to perform the appropriate coupling and fixing as described above.

In this case, in this embodiment, the low clutch is operated to function as a central control friction element accompanied by slip control during gear shifting. Here, the centralized control friction element to be controlled in this control means the following. That is, in a certain shift in A / T, the friction element is engaged before and after the shift, and the friction element slips while the transmission torque is controlled to a target value during the shift.

The power transmission train shown in the figure includes friction elements L / C, OR / C,
Various combinations of B / B, H / C, LR / B, and R / C as shown in the following table (○ indicates fastening (operation), no symbol indicates release (non-operation),
It should be noted that the symbol “△” indicates that the gears are not involved in each of the predetermined gears (the gears do not change even when they are actuated), thereby changing the rotation state of the elements constituting the planetary gear sets 4 and 5, thereby changing the input rotation speed. The output rotation speed can be changed,
As shown in the following table, it is possible to obtain four forward speeds and one reverse speed.

[0013]

[Table 1]

In this case, the low clutch L / C is used for full speed change (1-2, 2-3, 3-
In 4), the clutch is engaged both before and after the shift, but by slipping during the shift, the heat load on other friction elements to be switched during the shift can be reduced. Preferably, the low clutch can be used with a correspondingly increased capacity when acting as a central control friction element.

The automatic transmission further includes a control valve 30 (FIG. 1). The control valve 30 forms a shift control hydraulic circuit, and further includes a line pressure solenoid, a shift solenoid for selecting a shift speed, and a centralized solenoid. Actuator 31 for low clutch L / C as a control friction element
Is provided. The actuator is provided for use in supplying hydraulic P _{L / C} control, such as described below to the low clutch L / C, L / C pressure control means configured to include the same.

The control valve unit includes the actuator for the central control friction element, and includes a controller (A / TCU) 4.
Controlled by 0, this controller, the rotary input shaft for detecting throttle opening TH (accelerator opening) signal, a signal from an engine speed sensor 41 for detecting an engine speed N _E, an input shaft rotational speed N _IN signals from several sensors 42, for inputting a signal from the output shaft rotational speed sensor 43 for detecting an output shaft rotational speed N _OUT. The controller 40 includes an input detection circuit, an arithmetic processing circuit, and a shift control program (FIG. 3) including L / C oil pressure control for shifting to the low clutch L / C (during shifting) executed by the arithmetic processing circuit. An example of which is shown in a flowchart), a microcomputer including a storage circuit storing various arithmetic programs such as required data, required data, and the like, various solenoids of the control valve unit, an output circuit for sending a drive signal to the actuator 31, and the like.
Transmission control and other necessary control based on the input information are executed.

The shift circuit stores shift point characteristic data (see FIG. 5) applied to upshifting and downshifting, and here, the transmission torque of the low clutch L / C is stored. A torque converter slip ratio (H _IN / N _E ) applied to perform torque control to control (i.e., slide the low clutch to control the output torque during shifting) during gear shifting.
Torque amplification ratio (t _S ) characteristics and engine speed (N _E )
-Table data (see Figs. 6 and 7) on the engine output torque (T _E ) characteristic is also stored.

FIG. 3 shows an example of the contents of the shift control according to the present control. Hereinafter, the contents will be described with reference to FIGS. The 1 → 2 shift by the gear train in FIG.
This is achieved by fastening B from the released state. Therefore,
In this shift, B / B is a fastening element, and is a friction element that switches during switching (switches from disengagement to engagement). On the other hand, the low clutch (centralized control friction element), pre-shift (the first speed), is a fastening least after the shift (at second speed), the shift time (shift command of FIG instant t ₀ ~ shift end instant t ₂ ) controls the oil pressure as follows to realize 1 → 2 shift.

Referring to FIG. 3, first, in step 101, the speed change is carried out from the input throttle opening TH and the output shaft rotation speed N _{OUT in} accordance with the shift line characteristics of FIG. It is determined whether or not to perform the shift, and if the shift should be performed, what kind of shift is to be performed. Now, in such a judgment 1
→ If the result indicates that two shifts are to be obtained, then raise the hydraulic pressure of the friction element (in this example, the band brake B / B) to be engaged according to the type of shift. On the other hand, during the shift, the hydraulic pressure P _{L / C} of the low clutch L / C is controlled as shown in FIG. 4 from step 102 onward to perform slip control, and the 1 → 2 shift is advanced.

That is, in step 102, a process for calculating the L / C oil pressure during shifting based on the following equation is executed.

## EQU1 ## P _{L / C (1-2)} = {(T _{L / C} / N ・ idｄμ) + F｝ / A -1 T _{L / C} = T _E × t _S --- 2 The above shows how to calculate the low clutch pressure at the time of shifting for slip control of the low clutch L / C. The torque amplifying ratio t _S in Formula 2 Two, which from the characteristics of FIG. 6, the ratio N _IN / N _E and the input shaft rotational speed N _IN and the engine speed N _E
Together determine what value corresponding to the torque converter slip ratio is, for the engine output torque T _E, of a value corresponding to N _E at that time from the characteristic of the throttle opening TH, as shown in FIG. 7 as a parameter Then, the T _{L / C} value obtained by multiplying these values is applied to Equation 1. Furthermore,
In Equation 1, the above T _{L / C} , the number N of plates of the low clutch L / C, the torque share ratio i, the effective fading diameter d, the friction coefficient μ, the return spring force F, and the piston area A are also used. To find P _{L / C (1-2)} ,
An output process of outputting this as a shift-time hydraulic command value in step 103 is executed, and as shown in FIG. 4D, the actuator 31 reduces the low clutch L / C pressure during the shift.
Is controlled by In FIG. 4, the change trend of (i) engine speed N _E, the (b) is 1 → 2 change transition of the relative rotation N _{B / B} of the band brake B / B is a coupling element of the transmission, (C) shows the relative rotation N of the low clutch L / C.
Changes in _{L / C} are shown respectively.

On the other hand, in step 104, a process for outputting the hydraulic pressure of the fastening element (2nd B / B pressure) is executed. With regard to such engagement, the band brake B / B can simply be switched to the engagement and used as an element to be immediately connected, since the low clutch L / C is responsible for slip control.

Thus, the 1 → 2 shift is started by the above control.
Shift, and meanwhile, end the gear shifting in step 105
Monitor for Regarding the content of the shift end determination,
As the shift progresses, the gear ratio changes, for example, in 1 → 2 shift.
Gear ratio equivalent to after speed, ie, 2nd gear ratio g_Two Declines towards
And N_INAnd N_OUTAnd the ratio N_IN/ N_OUTHowever, in this example, N
_IN/ N_OUT≒ g_TwoTo check if you reach
Can be done with As a result, it is determined that the shift is completed.
(When instant t_Two), Step 105 selects step 106
After that, the process is shifted to the L / C pressure output processing at the steady state. Take
In the constant control,

## EQU2 ## P _{L / C} (steady state) = {(T _{L / C} / N · i · d · μ) + F} / (A × C) −3 where C is a safety factor of about 1.2 times. Then, the steady-state low clutch L / C oil pressure is calculated and determined, and as shown in FIG. 4, the actuator 31 is controlled so that the engagement oil pressure is again in the engaged state.

The shift control including the slip control for the low clutch L / C has been described above with reference to FIG. 4 taking a 1 → 2 UP shift as an example. It can be executed by shifting. For example, in the case of a 2 → 3 shift, the band brake B /
B is released and the high clutch H / C is engaged to perform this. During the 2 → 3 shift, the control in steps 102 and 103 is applied to the low clutch L / C as described above. In step 106, steady-state control before and after shifting is performed. In this case, the content of step 104 is a program that executes the release element B / B pressure output and the engagement element H / C pressure output processing according to the type of shift determination (2 → 3 shift) in step 101. What should I do? Other shifts can be implemented according to the above.

According to the above control, it is possible to control the transmission torque of the low clutch L / C as a central control friction element that is engaged before and after the shift, and the low clutch L / C is slid to change the speed during the shift. Can be controlled by controlling the output torque of the friction element, and the heat load of the other friction elements to be switched at the time of shifting can be reduced correspondingly. This centralized control friction element type automatic transmission is also effective in both weight size and shift shock.

In the case of control according to the shift time chart of FIG. 10 shown as a comparative example, this is also compared with FIG.
The change of _{NE and} the change of NB _{/ B} during the 2nd shift (the same (a) and (b)) are shown. In this case, the band brake B / B slips in the 1 → 2 shift. Therefore, B / B generates a large amount of heat (at this time, as shown in FIG. 10, the relative rotation N _{L / C} of the low clutch L / C and the hydraulic pressure (P) thereof). are each (c), those such as (d), in the gear shift (t ₀ ~t ₂₎ also, the low clutch L / c
Does not perform the slip control as shown in (c) and (d) of FIG. On the other hand, in the case of the present control, the element switched by the shift does not generate heat as in the comparative example (small heat generation), and it is easily possible to use only the timing. Low clutch
The L / C is mainly used as the heat load element when performing slip control of all shifts, and only one heat load element is required. Therefore, the band brake B / B, the high clutch H / C, etc. Can be reduced in size and weight, and reduction in weight can be achieved.

The shift shock can be determined by the low clutch L / C. Therefore, even if the friction element to be changed by the shift is set to a small and light one as described above, the shift shock which would occur if the band brake B / B were strongly applied to reduce the heat load in the comparative example. Can be avoided, and it is possible to achieve both the weight size and the shift shock. Furthermore, since the low clutch L / C is responsible for slip control during shifting to control the shock by slipping it, other friction elements B / B, H / C, etc.
As a result, the control hydraulic pressure can be made rougher, and as a result, the hydraulic circuit can be simplified as compared with a hydraulic circuit not employing this control.
Therefore, this also contributes to the reduction in size and weight. Further, as shown in FIG. 10, one low clutch L / C
Without controlling the transmission torque during gear shifting for each gear, in the case of 1-> 2 gear shifting in each gear, the gear is changed by B / B, H / C, etc. When the medium torque is output, the torque waveforms that affect the shift shock in all shifts tend to be different, and as a result, the mode of the torque fluctuation is also different, but according to this control, B / B to switch when shifting
, H / C and the like can be avoided as a result of the slip control of the low clutch L / C so as to absorb the torque fluctuation due to the shift of the friction element such as H / C. In each shift, the low clutch L / C is always subjected to slip control and can be realized by the slip control of one low clutch L / C, so that it is consistent with shift shock. It can be done easily.

Next, another embodiment of the present invention will be described. In the present embodiment, the low clutch 1 / C is also provided with slip control during shifting. In this case, the shift time is controlled to further limit the amount of heat generated. Hereinafter, similarly, the case of 1 → 2 shift will be described as an example. In the case of this embodiment, similarly, input torque calculation or detection means, L / C pressure control means, and shift determination end means are provided.
Basically, the shift is realized in accordance with the flowchart of FIG. 3, but as shown in FIG. 8, the control contents of the main part are different from those of FIG.
203 is added. Steps 101 to 10 in FIG.
3 is the same, and is not shown in FIG. FIG. 9 shows the engine rotational speed N _E (FIG. 9 (a)) under the control of the embodiment, and the engagement hydraulic pressure (2nd B / B) for the band brake B / B which is the engagement element for the 1 → 2 shift. Pressure)
(Same as (b)), low clutch L /
Before the gear shift (t ₀ ) for each of the control pressures (C) for C
Before) shows an example of changes over during the shift, and after the shift (after t _2). Further, a dashed line in FIG. 7A indicates a target engine speed, and Δt indicates a target shift time.

In FIG. 8, steps 101 to 101 in FIG.
After the process of 103, the process proceeds to step 104,
Outputs the fastening element pressure (2nd B / B).
In the same manner as described above, a shift end determination is made based on N _IN / N _OUT = g _{2. In} this case, if the shift is in progress,
Further, in step 201, it is checked whether the engine speed is higher than the target value, and according to the result, the L / C pressure is corrected upward (increase correction) or corrected downward (increase correction) to control the amount of heat generated by controlling the shift time. Make a correction (step)
202, 203).

In the case of FIG.
202 is the selected case, and the low clutch L / C oil pressure is corrected to increase as shown in FIG. 3 (c) (that is, the degree of decrease in L / C pressure during slip control by the low clutch is determined. By making it smaller (correcting P _{L / C (1-2)} according to the above formula 1 to a larger value), the 1 → 2 shift is advanced by the slip control using the corrected L / C pressure. (T ₁
~t between _2). Thus, by correcting the L / C pressure at the time of shifting, the shifting time (t _{0 to} t ₂ ) can be controlled to limit the amount of heat generated. If it is determined that the shift is completed, the process proceeds to the steady-state L / C pressure output process (step 110) as in the above embodiment.

In this embodiment, the same operation and effect as those described in the above embodiment can be obtained. In addition, the amount of generated heat can be more appropriately limited, and fine control can be performed.

The present invention is not limited to the embodiment described with reference to FIGS. For example, in all of the above embodiments, the low clutch L / C is used as the first friction element. However, for example, the high clutch H / C at the time of 3 → 4 shift may be used as the first friction element of the present invention. Needless to say, the present invention is not limited to the case where the controlled friction element is between the input shaft and the speed change means (main power train) or between the speed change means and the output shaft. it can.

[0032]

According to the present invention, a frictional element to be engaged before and after a gear shift is set as a frictional element to be controlled in the slip control at the time of gear shifting, and the frictional element is slid during the gear shifting to control the transmission torque during the gear shifting. Function to reduce the heat load on the other friction elements that are switched at the time of shifting, and absorb the torque fluctuation due to the shifting of the switching of the other friction elements. It is possible to easily realize compatibility of shocks and the like.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the apparatus of the present invention.

FIG. 2 is a diagram illustrating an example of a power transmission train of the automatic transmission.

FIG. 3 is a flowchart showing an example of control contents by a controller in the case of 1 → 2 shift.

FIG. 4 is an example of a shift operation time chart of the same example.

FIG. 5 is a diagram illustrating an example of shift line characteristics.

FIG. 6 is a diagram illustrating an example of a torque converter slip ratio-torque amplification ratio characteristic.

FIG. 7 is a diagram showing an example of an engine speed-engine output torque characteristic.

FIG. 8 is a flowchart illustrating a main part of another example of the control performed by the controller.

FIG. 9 is an example of a shift operation time chart in the same example.

FIG. 10 is a time chart in a comparative example shown in comparison with FIG.

[Explanation of symbols]

 20 Transmission mechanism 30 Control valve 40 Controller H / C High clutch B / B Band brake R / C Reverse clutch LR / B Low reverse brake LO / C Low one-way clutch OR / C Overrun clutch L / C Low clutch (forward clutch) FO / C forward one-way clutch

Claims (3)

(57) [Claims] 1. A shift control apparatus for an automatic transmission which performs a shift by engagement and disengagement switching of the friction elements, Orazu frees both the front and rear transmission in one transmission, fastening
A control pressure control means for the first friction element control target friction elements that, release form prior to transmission by the friction elements other than the friction elements of the first
State to the engaged state after shifting, or the engaged state before shifting
A plurality of second friction elements that are switched from the gearshift to the released state after the shift
And containing, during shifting, before the be fastened or released switched nuclear
And a fastening and release control means for the serial second friction element, the control pressure control means, the fastening of at least one or more release before <br/> Symbol second friction element by the engagement and disengagement control means
Shifting from engaged or disengaged to achieve shifting
During a shift to, based on the input torque of the transmission during this speed-change
As controls the transmission torque to control the output torque Te
Absorbs torque fluctuations due to shifting of the switching of the second friction element
A shift control device for an automatic transmission , wherein slip control is performed on the first friction element so as to perform slip control. 2. The control pressure control means according to claim 1,
A shift control device for an automatic transmission, wherein a control pressure in slip control for a first friction element is corrected to control a shift time. 3. The automatic transmission according to claim 1, wherein the controlled friction element is a friction element between the input shaft and the transmission means or a friction element between the transmission means and the output shaft. Control device.