JPH07107423B2 - Shift control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shift control device for an automatic transmission, and more particularly, to smoothly perform an upshift shift accompanying a transition of a power source of the automatic transmission to a power-off state. The present invention relates to a shift control device for.

(Prior Art) In an automatic transmission, various friction elements (clutch, brake, etc.) of a speed change gear mechanism are selectively activated to select a predetermined gear stage, and the friction element to be operated is changed to another gear stage. Shift gears.

By the way, when the power source of the automatic transmission is switched to the power-off state, for example, the engine throttle opening (TH) is changed from the point X on the shift pattern (only the upshift line is shown for convenience) as shown by the solid line in FIG. When switching to fully close (release the accelerator pedal) to the point Y, the automatic transmission determines the upshift from the first speed to the second speed and performs the corresponding 1 → 2 upshift. To do. If the foot release upshift is not executed when the input rotation is in sync with the output rotation (vehicle speed) of the transmission gear mechanism when the gear ratio of the transmission is taken into consideration, the transmission output torque is zero. Therefore, gear striking sound and rattling vibration are generated due to backlash of the differential gear.

Therefore, the applicant of the present application has previously proposed, in Japanese Patent Application No. Sho 62-282252, to perform a corresponding upshift when the gear ratio represented by the ratio between the input and output speeds of the speed change gear mechanism reaches a set value. A shift control device has been proposed.

This device functions as follows when describing the foot release 1-> 2 upshift transmission in FIG. After the 1-> 2 upshift determination at the instant t _{1 when} the throttle is fully closed, the engine speed N _E , the turbine speed (transmission input speed) N _{T of} the torque converter, and the transmission output speed N _O (in the figure, The values N _O × 1.169 in consideration of the gear ratio of 1.169 after the second speed change are shown as solid lines, respectively, and the apparent gear ratio g = N _T / N _O of the transmission gear mechanism is It decreases as. From the instant t ₂ when the gear ratio g drops to the set value g _{1, the} shift solenoid A is turned off to increase the second speed selection pressure P _{2 as shown} by the solid line to perform 1 → 2 upshift gear shifting, and N _T = N _O ×
1.169 and g = 1.169 are set, and the shift is completed. Therefore, this gear shift is always executed reliably when the input speed N _T almost matches the value N _O × 1.169 in consideration of the gear ratio 1.169 after the shift with respect to the output speed N _O. Even if the output torque is zero as shown by the solid line, it is possible to prevent the generation of gear hammering noise and rattling vibration due to backlash of the differential gear or the like.

(Problems to be Solved by the Invention) However, in such a configuration, the engine speed N _E and the turbine speed N _E are caused by variations in the power source (engine) and the torque converter, changes over time, warm-up operation of the engine, and the like. _{When T} does not show a predetermined decrease as shown by the dotted line in FIG. 13, the gear ratio g cannot be decreased to the set value g _{1 as} shown by the dotted line, and the shift solenoid A is not switched ON → OFF as shown by the dotted line. Therefore, the above-mentioned upshift is not executed.

To solve this problem, the shift solenoid A is forcibly switched from ON to OFF at the instant t _{3 at} which the elapsed time T from the foot release upshift determination instant t ₁ reaches the set time T _S as shown in FIG. It is conceivable to forcibly execute the corresponding 1 → 2 shift by the second speed selection pressure P _{2 which} rises to the line pressure P _{L as the} number of points.

However, when this forced shift is performed, the gear ratio g is a shift when the gear ratio is significantly different from the post-shift gear ratio (1.169 in Fig. 14), so the friction element that was activated during the shift is slipped. However, even if it is necessary to engage the friction element more slowly than usual, if the working hydraulic pressure of the friction element is normal, the engagement of the friction element will be too rapid and a large shift shock will occur. In other words, explaining this situation with Fig. 14,
From t ₃ , the transmission input speed N _T rapidly increases as shown by the dotted line N _O ×
It decreased toward 1.169, and the transmission output torque also had peak torque as shown by the dotted line,
This causes a big shift shock.

(Means for Solving the Problems) The present invention is intended not only for forced gear shifting as described above but also for gear shifting at this time without shock. As shown in the concept of FIG. The various gear elements of the mechanism are selectively actuated to determine the predetermined gear, and the friction element to be actuated is changed to another gear, and the power source of the gear shift mechanism is shifted to the power-off state. After the upshift determination by the above, when the gear ratio represented by the ratio between the input and output speeds of the transmission gear mechanism reaches the set value, the automatic transmission that performs the corresponding upshift gear shift,
The measuring means for measuring the elapsed time after the upshift determination, the forced shift means for forcibly starting the upshift shift when the elapsed time reaches the set time, and the operation during the shift An operating pressure reducing means for reducing the operating pressure of the friction element is provided.

(Operation) The speed change gear mechanism selectively operates various friction elements to select a predetermined shift speed, and accelerates / decelerates the supplied power at this shift speed and outputs the power. Then, the transmission gear mechanism is shifted to another shift stage by changing the friction element to be operated.

Then, after the upshift determination due to the power source of the transmission gear mechanism shifting to the power-off state, when the gear ratio reaches the set value, the corresponding upshift shift is executed.
Therefore, if the output torque at the time of shifting is zero, it is possible to obtain shift control without causing gear hitting sound or rattling vibrations due to gear backlash.

By the way, in the state where the gear ratio does not decrease to the set value after the upshift determination and the above gear shifting is not performed, the forced gear shifting means responds to the timing means that measures the elapsed time after the upshift shifting determination. When the set time has elapsed after the shift determination, the corresponding upshift gear shift is forcibly started. Therefore, it is possible to prevent the foot release upshift from being left unexecuted.

Then, during this gear shift, the working pressure lowering means lowers the working pressure of the friction element that was activated during the gear shift. For this reason, the frictional element is engaged more slowly than usual while slipping, and the gear input when the gear ratio is far away from the gear ratio after gear shifting also causes the gear input speed to gradually change to the gear output. The value can be brought to a value corresponding to the number of revolutions (the gear ratio can be gradually matched with the gear ratio after shifting), and a large shift shock can be prevented from occurring.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 2 shows a power train control system of an automobile incorporating a shift control device of the present invention, 1 is an electronically controlled fuel injection engine, 2 is an automatic transmission, 3 is a differential gear, and 4 is a differential gear.
Is the driving wheel.

The engine 1 includes an engine control computer 5, which includes a signal from an engine rotation sensor 6 for detecting an engine speed N _E , a signal from a vehicle speed sensor 7 for detecting a vehicle speed V, and an engine throttle opening TH. The signal from the throttle sensor 8 for detecting, the signal from the intake air amount sensor 9 for detecting the engine intake air amount Q, etc. are input. The computer 5 determines the fuel injection pulse width T _P based on these input information and commands it to the engine 1, or supplies an ignition timing control signal (not shown) to the engine 1. The engine 1 is supplied with an amount of fuel according to the fuel injection pulse width T _P, and operates by burning this fuel in synchronism with the rotation of the engine.

The automatic transmission 2 is described in "RE4R01A Type Automatic Transmission Maintenance Manual" (A261C07) issued by Nissan Motor Co., Ltd. March 1987. It has a torque converter 10 and a speed change gear mechanism 11 in tandem, The engine power is input to the input shaft 12 via 10.
The input rotation of the transmission to the shaft 12 is accelerated and decelerated according to the selected speed of the transmission gear mechanism 11 to reach the output shaft 13, from which the drive gear 4 is passed through the differential gear 3 to drive the vehicle. it can.

The speed change gear mechanism 11 incorporates various friction elements (not shown) such as clutches and brakes that determine a transmission path (speed stage) from the input shaft 12 to the output shaft 13, and is operated to select a predetermined speed stage. At the same time, the gear shift to another gear is performed by changing the friction element to be operated.

A shift control computer 14 and a control valve 15 are provided for this shift control. The computer 14 is a shift solenoid A, B for shift control in the control valve 15.
To control the shift control by selectively supplying the line pressure P _L to various friction elements so that the corresponding shift stage is selected by the combination of ON and OFF of these shift solenoids shown in the following table. .

The shift control computer 14 also controls the line pressure control duty solenoid 16 in the control valve 15 by the drive duty D to control the line pressure P _L in the control valve 15 (the line D increases as the duty D increases as shown in FIG. 10). Pressure rise) shall be controlled as prescribed. Computer for shifting control and line pressure control
A signal from the vehicle speed sensor 7 and a signal from the throttle sensor 8 are input to 14, and a signal from an input rotation sensor 17 for detecting the rotation speed N _T of the shaft 12 and a rotation speed N _O of the shaft 13 are detected. The signal from the output rotation sensor 18 and the signal I _d from the idle switch 19 that is turned on when the accelerator pedal of the engine 1 is released (when TH = 0) are input.

The computer 14 executes the control program of FIGS. 3 to 6 to perform the shift control according to the present invention.

First, to explain the main routine of FIG. 3, which is repeatedly executed by a timed interrupt every 10 msec, for example, steps 21, 2
In 2, the vehicle speed V, the throttle opening TH, the input speed N _T and the output speed N _O are read, and in step 23 the speed change gear mechanism 11 is read.
The gear ratio g = N _T / N _O of the
Table data corresponding to the figure (however, 2 → 1,3 → 2,4 → 3
The shift speed is determined from the vehicle speed V and the throttle opening TH based on (the downshift line is omitted), and whether or not the shift is necessary is determined in step 25 depending on whether the determined shift speed is different from the currently selected shift speed. Determine.

If gear shifting is not required, shift solenoids A and B O
A decision is made to maintain the current gear without switching between N and OFF.In the next step 27, the solenoid drive signal is output to the shift solenoids A and B in accordance with this decision, and in step 28 the line pressure solenoid is operated as described later. 16 drive duty D
Is output to the solenoid 16.

If a gear shift is necessary, first, at step 29, it is identified what speed the gear shift is from the currently selected gear, and at the next step 30, it is checked whether or not gear shift is already in progress, that is, whether or not gear shift determination has been completed. Before the shift determination, the timer T for measuring the elapsed time after the shift determination is reset in step 31, and after the shift determination, the timer T is incremented in step 32 to measure the elapsed time after the shift determination.

In step 33, it is checked whether or not the measured time of the timer T is equal to or longer than the set time T _S, and if T <T _S, step 3
After performing the normal shift control by 4, 35 and 27 as follows, in step 28, the normal line pressure control described later is performed.

In step 34, the gear ratio set value, which is the criterion for starting the shift, is looked up in the table by the subroutine of FIG. 4. First, in steps 41 and 42, the shift solenoid which can be known from the type of the shift (see step 29). A,
Set the pre-shift state and post-shift state of B. Next, in steps 43 and 44, table data for each type of shift (table data for 1 → 2 shift in FIG. 7 and table data for 1 → 4 shift via third speed in FIG. 8 are illustrated. ), The gear ratio set values g ₁ and g ₂ for the shift solenoid A and the gear ratio set values g ₃ and g ₄ for the shift solenoid B are looked up from the throttle opening TH and the idle signal I _d .

These gear ratio setting values are set to 0
Corresponds to the reference value of the gear ratio for determining whether to switch N, OFF (shift should be started). Two kinds of gear ratio set values g ₁ , g ₂ and g ₃ , g ₄ are set for the shift solenoids A and B, respectively, as shown in FIG. The shift solenoid is turned on, for example.
This is because it is necessary to switch from OFF to ON. Therefore, when the jump shift is not performed, for example, as shown in FIG. 7, the gear ratio set values g ₁ and g ₂ are made the same, and g ₃ and g ₄ are made the same.

In step 35 in FIG. 3, depending on what the gear ratio g (see step 23) is with respect to the above gear ratio setting value, the subroutine in FIG. ON, OFF) is determined as follows.

First, in step 51, it is determined whether it is an upshift or a downshift. If it is an upshift, it is checked in steps 52 and 53 whether or not the gear ratio g is below the set values g ₁ and g ₂ . When g> g _1, the pre-shift state of shift solenoid A is set in step 54 (see step 41), and when g ≦ g ₁ and g> g ₂ , the shift solenoid A is in the opposite state to the pre-shift state. Then, the ON / OFF switching is set so that g ≦ g ₂ is reached and the post-shift state of the shift solenoid A (see step 41) is set.

After that, in steps 57 to 61, the gear ratio g and set value are the same as above.
By comparing with g ₃ and g ₄ , the shift solenoid B is set to the pre-shift state, the reverse state, or the post-shift state.

Also, when it is determined that a downshift is performed in step 51, similarly to the above, steps 62 to 71 set the pre-shift state, the reverse state, or the post-shift state of the shift solenoids A and B.

After determining the states of shift solenoids A and B in this way,
In step 27 in FIG. 3, a solenoid drive signal is output to the shift solenoids A and B so as to obtain the set state.

As a result, the automatic transmission automatically selects the first speed, the second speed, the third speed or the fourth speed in accordance with the shift pattern shown in FIG. 12, and the shift line (downshift line in FIG. 12). (When omitted), the corresponding automatic shift can be performed when the operating state is changed so as to pass through. During this gear shifting, the gear shifting is started when the gear ratio g reaches the set values g ₁ , g ₂ , g ₃ , g ₄ , so that the gear input speed is changed relative to the gear output speed (vehicle speed). The gear shift is executed at the time of the synchronization in which the latter gear ratio is taken into consideration, and the gear shift shock can be suppressed to the minimum.

When it is determined in step 33 in FIG. 3 that T ≦ T _S , that is, when the set time T _S after the shift determination has elapsed, it is determined in step 36 that the shift solenoids A and B are turned on and off in the post-shift state. Then, in step 37, the flag PLFLG for instructing the change of the line pressure to achieve the object of the present invention during the forced gear shift is set to 1. After that, in step 27, the shift solenoids A and B are turned on and off to correspond to the command of step 36 and forced shift is performed, and in step 28, the line pressure is changed in response to PLFLG = 1 as described later. To do.

According to such a forced shift, for example, as shown by the dotted line in FIG. 13, the input rotation speed _NT does not decrease easily and the gear ratio g does not reach the set value (g _{1 in} FIG. 13), so that the shift is not performed. even if not so, the elapsed instant t ₃ of the set time T _S from the speed change decision instant t ₁ as shown upshift releases the foot in Figure 14 the solid line
Can be surely executed.

Next, the line pressure control executed at step 28 in FIG. 3 will be explained by the subroutine shown in FIG. That is, first, at step 81, it is checked whether the line pressure change flag PLFLG is 1 or not, that is, whether the line pressure should be changed (decreased) because the above-mentioned forced shift is performed and a shift shock becomes a problem.

If PLFLG = 0, there is no need to do so. Therefore, in steps 82 to 85, normal line pressure control is performed as follows. That is, it is checked in step 82 whether or not the 1-> 2 shift is made, and if so, it is checked in step 83 whether the idle switch 19 is ON (engine power off) from the signal Id. Then, in step 84 (engine power off) or 85 (engine power on), the drive duty D of the line pressure solenoid 16 is looked up from the corresponding table data illustrated in FIG. 9 and output. In step 82, 1
→ When it is determined that the shift is other than the 2nd shift or the non-shift is being performed, the line pressure solenoid drive duty is similarly looked up from the corresponding table data and output, and the normal line pressure (P _L ) control can be performed. .

At the time of the forced shift in which it is determined that PLFLG = 1 in step 81, it is determined in step 86 whether the shift is 1 → 2, and if so, it is determined in step 87 whether the idle switch 19 is ON (engine power off) based on the signal Id. To check something. And step
At 88 (engine power off) or 89 (engine power on), the drive duty D of the line pressure solenoid 16 is looked up from the corresponding table data illustrated in FIG. 10 and output. When it is determined in step 86 that the forced shift is other than 1 → 2, the line pressure solenoid drive duty is similarly looked up from the corresponding table data and output to output the line pressure (P _L ) control for the forced shift. I do.

Then, when this forced shift is completed, step 90
Is because the gear ratio g matches the gear ratio after shifting,
Select step 91 where PLFIG = 0. Therefore, after that, return to the normal line pressure control loop 82 to 85,
It does not interfere with the line pressure control after the forced shift.

By the way, comparing FIG. 9 and FIG. 10, the duty D (line pressure P _L ) during engine power off (TH = 0) when the accelerator pedal is released (TH = 0) is more than that during normal gear shifting (FIG. 9) during forced shift ( Lower (Fig. 10). By making the line pressure during forced shift lower than usual as described above, the accumulator back pressure (back pressure to the accumulator (not shown) provided for gear shift shock prevention) P _A also decreases accordingly. Referring to the forced foot release 1 → 2 upshift gear shift in FIG. 14, the second speed selection pressure P ₂ (friction element operating pressure) is instantaneous.
The input speed N _T rises gradually from t ₃ as shown by the solid line.
Also, the decrease in the gear ratio g becomes gentle as shown by the solid line, and the shift shock can be reduced as is apparent from the transmission output torque waveform also shown by the solid line.

In addition, during engine power-on in Fig. 9 and 10 (TH <
The duty D (line pressure P _L ) (0) is set to be greater during forced shift (FIG. 10) than during normal operation (FIG. 9) even with the same throttle opening. The reason for this is that the forced shift during engine power-on is to eliminate the state in which shifting is impossible due to excessive engine output torque, so that the line pressure corresponds to a large engine output torque.

(Effect of the Invention) Thus, as described above, the shift control device of the present invention forces the shift to be performed after the set time in a state in which the shift corresponding to the upshift shift accompanying the transition to the power-off state cannot be executed. At this time, since the operating pressure of the friction element is reduced, the friction element is engaged more slowly than usual while sliding the friction element during gear shifting, and the gear ratio is greatly separated from the gear ratio after gear shifting due to forced gear shifting. It is possible to prevent a large gear shift shock from occurring in the gear shift and the lid.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a shift control device of the present invention, FIG. 2 is a control system diagram of a vehicle power train showing one embodiment of the device of the present invention, and FIGS. 3 to 6 are each for shift control in the same example. 7 is a flowchart showing a control program of a computer, FIGS. 7 (a) and 7 (b) are characteristic diagrams of a gear ratio set value for 1 → 2 shift, and FIGS. 8 (a) and 8 (b) are 1 → 4 shift, respectively. Characteristic diagram of gear ratio set value, FIG. 9 and FIG. 10 are diagrams exemplifying the line pressure solenoid drive duty at the time of normal and forced shift, respectively, and FIG. 11 is the line pressure and accumulator back pressure change characteristic with respect to the drive duty. FIG. 12 is a shift pattern diagram of the automatic transmission, FIG. 13 is a shift operation waveform diagram of the conventional device, and FIG. 14 is a shift operation waveform diagram of the device of the present invention. 1 ... Electronically controlled fuel injection engine 2 ... Automatic transmission 3 ... Differential gear 4 ... Drive wheels 5 ... Engine control computer 6 ... Engine speed sensor 7 ... Vehicle speed sensor 8 ... Throttle sensor 9 ... … Intake air amount sensor 10 …… Torque converter 11 …… Shift gear mechanism 14 …… Shift control computer 15 …… Control valves A, B …… Shift control shift solenoid 16 …… Line pressure control due solenoid 17 Input rotation sensor 18 Output rotation sensor 19 Idle switch

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Claims (1)

[Claims] Claim: What is claimed is: 1. Various friction elements of a speed change gear mechanism are selectively actuated to determine a predetermined speed stage, and the speed of the speed change gear mechanism is changed by changing the friction element to be actuated. After an upshift determination due to a transition to a power-off state, when the gear ratio represented by the ratio between the input and output speeds of the transmission gear mechanism reaches a set value, an automatic transmission that performs a corresponding upshift shift In the above, the time measuring means for measuring the elapsed time after the upshift determination, the forced shift means for forcibly starting the upshift shift when the elapsed time reaches the set time, and being operated during this shift. A shift control device for an automatic transmission, comprising: an operating pressure reducing means for reducing the operating pressure of the friction element.