JPH0527783B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is applicable to automatic transmissions for vehicles, and particularly relates to a shift shock reduction device for automatic transmissions that can reduce shift shocks. Regarding.

(Prior Art) Conventional gear shift shock reduction devices for automatic transmissions include, for example, Japanese Patent Application Laid-Open Nos. 52-106064 and 1982-106064.
There is something described in No. 85264.

The conventional device described above detects the output shaft torque of an automatic transmission with a torque sensor, and changes gears while feeding back the detection signal of the output shaft torque so that the output shaft torque changes in accordance with a preset torque change. The aim is to reduce shift shock by controlling the fluid pressure of the hydraulic friction element used in the transmission.

(Problem to be Solved by the Invention) However, the above conventional device detects the output shaft torque of the automatic transmission with a torque sensor and feeds back this detection signal, but the actual change in the output shaft torque is not detected in advance. Since it is configured to perform real-time control in accordance with the set torque change,
If such control is to be performed using a digital arithmetic circuit such as a microcomputer, an expensive device capable of high-speed arithmetic operations will be required.

In addition, for real-time control as mentioned above,
If an error component from the nozzle or the like is mixed into the torque sensor output, control accuracy will immediately drop, and to prevent this, a highly accurate torque sensor, that is, an expensive torque sensor, is required.

(Means for solving the problem) In order to solve the above problem, the first invention
It is equipped with the means shown in FIG. 1A.

Torque sensor 101 detects output shaft torque of automatic transmission 100.

The engagement start time detection means 102 detects the start time of engagement of the fluid pressure friction element 105 for shifting that constitutes the automatic transmission 100 during shifting, based on the fluctuation waveform of the output shaft torque detected by the torque sensor 101. .

The reversal point detection means 103 detects when the friction element 10
After the fastening start time point No. 5 is detected, first, the time point when the direction of increase/decrease change in the output shaft torque is reversed is detected.

The supply pressure control means 104 reduces the supply pressure to the friction element 105 by a predetermined amount from the time of starting the engagement to the time of reversal, and then gradually increases the supply pressure.

As shown in FIG. 1B, a second invention provides a torque sensor 1 that is the same as that constituting the first invention.
01, fastening start time detection means 102, reversal time detection means 103, and time measurement means 106.
and a supply pressure control means 107 that performs control different from that of the first invention.

The clock means 106 is the fastening start point detection means 10.
2, a predetermined time limit is counted from the time when the start of engagement of the hydraulic friction element 105 is detected.

The supply pressure control means 107 controls the friction element 10 from the time when the engagement starts to the time of reversal detected by the reversal time detection means 103 or until the time limit elapses, whichever comes first.
5 by a predetermined amount, and then,
The supply pressure is gradually increased.

(Operation) The first invention detects a remarkable change point in the fluctuating waveform of the output shaft torque during gear shifting by means of the fastening start point detection means 102 and the reversal point detection means 103,
By controlling the supply pressure to the fluid pressure friction element 105 in response to the arrival of these changing points, the detected value of the output shaft torque can be fed back in real time unlike conventional devices, and the torque change can be adjusted to the preset torque change. This can be realized using a digital circuit that has a slower arithmetic processing time than those to be compared. Furthermore, even if the detection signal of the torque sensor 101 is mixed with an error component caused by the nozzle, it has little effect on the detection of the above-mentioned significant change points, so there is no need to use a high-precision torque sensor, resulting in cost reduction. I can figure it out.

Furthermore, by controlling the supply pressure to the friction element 105 by the supply pressure control means 107, the occurrence of shift shock can be effectively reduced by setting the arrival of the above-mentioned change point as the supply pressure change timing.

In addition to the effects of the first invention, the second invention adds, as a condition for changing the supply pressure by the supply pressure control means 107, the point at which the time limit clocked by the clock means 106 has elapsed. When the supply pressure is reduced in response to the arrival of the time when the friction element starts to engage, the friction decreases due to the drop in the supply pressure due to individual differences in automatic transmissions and changes over time in the friction coefficient of the friction element. Even if the tightening pressure of the element weakens and it becomes difficult to detect the point in time when the direction of increase/decrease in the output shaft torque is reversed, the supply pressure is gradually increased from the point at which the above-mentioned time limit has elapsed, ensuring good gear shifting operation. (Embodiment) The configuration of an embodiment of the first invention is shown in FIG.

The control circuit 20A is mainly composed of a digital arithmetic circuit constructed using a microcomputer or other digital circuit. In the figure, some of the control functions are shown as functional blocks to make them easier to understand.

The information input to the control circuit 20A is the output shaft torque T _OUT of the automatic transmission (not shown) detected by the torque sensor 10 and the throttle opening sensor 11.
and the rotation speed N _OUT of the output shaft _of the automatic transmission detected by the output shaft rotation speed sensor 12.

The torque sensor 10 is a well-known magnetostrictive torque sensor (similar to the one described in the above-mentioned conventional publication), and since the output signal is an analog signal, an A/D converter is used in the control circuit 20. 30, it is converted into a digital signal. The output signals of the throttle opening sensor 11 and the output shaft rotation speed sensor 12 are digital signals.

The output signal output from the control circuit 20A is transmitted to a pressure control valve 40 that controls the fluid pressure of a fluid pressure type friction element for gear shifting that constitutes an auxiliary transmission mechanism of an automatic transmission.
This is the drive signal.

As shown in FIG. 3, the pressure control valve 40 is composed of a spool valve 51 and a solenoid valve 52, and controls the supply pressure supplied to the input oil path 55.
P _L (output pressure from the oil pump) is controlled by a fixed orifice 53 and a variable orifice 53 whose opening is adjusted by a solenoid valve 52.
By giving it to the spool valve 51 as P _C ,
The amount of displacement of the spool 51S is adjusted, and as a result, the output pressure P _S from the output oil passage 56 is adjusted.
The output oil passage 56 is connected to the hydraulic oil supply passage of the hydraulic friction element.

A drive signal I given to the pressure control valve 40 from the control circuit 20A is an exciting current for the solenoid valve 52, and this drive signal I
is a pulse width modulated current signal output from the PWM circuit (pulse width modulation circuit) 31 in the control circuit 20A.

That is, by changing the ON/OFF duty ratio of the drive signal I using the PWM circuit 31, the amount of displacement of the spool 52S of the solenoid valve 52 is adjusted, and the opening degree of the variable orifice 54 is adjusted. As a result, the output pressure P _S will be adjusted.

The control circuit 20A receives the above input information T _OUT , S _TH ,
Based on N _OUT , the hydraulic pressure to be applied to the hydraulic friction element for gear shifting is determined and control is performed to reduce gear shifting shock.The functional structure of this system is shown in Fig. 2. It consists of numbers 21 to 24.

The shift point determining unit 21 determines the gear position of the automatic transmission based on the throttle opening S _TH and the output shaft rotation speed N _OUT .

When the gear position is determined by the shift point determining unit 21, the pressure determining unit 22 recognizes a change in the gear position, that is, when a gear shift is performed, and determines the hydraulic pressure type for shifting at the time of the gear shift. A time change in the oil pressure of the friction element is set in advance (this set time change in oil pressure is referred to as a "reference oil pressure change").

The waveform recognition unit 23 receives the output shaft torque T _OUT and detects a singular point in the fluctuating waveform of the output shaft torque T _OUT during gear shifting. That is, the time point at which the hydraulic friction element starts to engage and, after the time point at which the engagement starts, is detected, the time point at which the direction of increase/decrease change in the output shaft torque is first reversed is detected.

The pressure change unit 24 predetermines the supply pressure to the friction element, which is determined according to the reference pressure change set by the pressure determination unit 22, each time a singular point detected by the waveform recognition unit 23 arrives. The pressure control valve 40 generates an output for forming a drive signal I to be applied to the pressure control valve 40 by changing the predetermined value.

FIGS. 4 and 5 show that when the control circuit 20A is configured using a microcomputer,
This is a flowchart showing the processing executed by this control circuit 20. The processes shown in FIGS. 4 and 5 are a series of processes, and are repeatedly executed at predetermined time intervals.

In the process of step 61 in FIG. 4, the input data of the throttle opening _STH and the output shaft rotational speed _NOUT are read.

In step 62, flag F for determining the control mode is set.
The content of the routine is determined to determine which routine to proceed to. This flag F is set as 2-bit data, and when it is "00" it indicates "not shifting" and when "01" it indicates "shifting". Note that when the ignition switch is turned on, flag F is reset to "00".

If the flag F=00 is determined as a result of the determination in step 62, then the operating conditions are determined in step 63, and the shift diagram stored in the memory in advance is updated in step 64. Based on this, it is determined whether the above operating conditions (determined by the throttle opening _STH and the output shaft rotational speed _NOUT ) exceed a shift point that requires a shift.

In step 66, the fluid pressure to be applied to the hydraulic friction element for gear shifting is determined by lookup processing of the data table of pressure data stored in the memory.

The above pressure data table (hereinafter referred to as "pressure data table") is based on the type of shift (for example, "1st gear → 2nd gear shift" or "2nd gear → 3rd gear shift").
etc.) and operating conditions (throttle opening _STH , output shaft rotation speed _NOUT , vehicle speed, etc.), and the required pressure data under each condition is stored.

When the pressure data corresponding to the conditions is obtained, in the next step 67, the flag F is set to 01 to memorize that "shifting" is in progress.

When the speed change operation is started as described above, the A/D converter 30 is activated and the data of the output shaft torque T _OUT is read by the process performed in step 71 of FIG.

In the next step 72, it is determined from the contents of the flag AF whether or not the time to start engaging the friction elements has passed. This flag FA is set to "01" when detected from the time when the friction element starts to be fastened.

Now, at time t _p in Figure 6, the decision in step 65 is made.
Assume that the answer is YES and the gear shifting operation is started.

Immediately after the shift starts, the flag FA=00, and the flag FB, which will be described later, is also "00", so in the process of step 79, the step
The pressure data P _F obtained in step 66 is output to the PWM circuit 31 as the pressure command value P. This results in
A fluid pressure equal to the pressure data P _F is supplied to the friction element.

In step 81, a process for detecting the start point of engagement of the friction elements is performed. This is A in Figure 6a.
It is a process of detecting a point, and the point at which this point A occurs
At _tA , since the friction element has started to engage and the clutch plate has started to be pressed, the output shaft torque T _OUT fluctuates (due to changes in load due to inertia components, etc.), and the output shaft torque rapidly decreases.
This is the point where T _OUT begins to decrease.

This detection of the start of engagement is performed by comparing the output shaft torque T _OUT read in step 71 with the output shaft torque read in the previous process, and detecting that the output shaft torque T _OUT decreases a predetermined number of times in succession. And when the amount of decrease in the output shaft torque during this period is greater than or equal to a predetermined value,
This is performed by the above-mentioned processing at the conclusion start time.

When the fastening start point is detected, the pressure data P _F is decreased by a predetermined amount ΔP ₁ in step 82 to form new pressure data (P _F −ΔP ₁ ). Then, in step 83, the flag FA is set to 01 to indicate that the fastening start time has passed.

Therefore, the duty ratio of the drive signal I from time t _O to t _A is the duty ratio for generating the pressure data P _F as shown by D ₁ in FIG. The fluid pressure begins to rise after some time delay _tS , as shown in Figure 6b.

Then, when time t _A passes, the above (P _F −
ΔP ₁ ), and the fluid pressure decreases by a predetermined amount from time t _A , as shown by P ₁ in FIG. 6b.

When the fastening start time has elapsed, the flag FA becomes 01, so the judgment in step 72 becomes YES, and the next step 73 determines that the reversal point of the output shaft torque T _OUT has elapsed based on the contents of the flag FB. Determine whether or not the This flag FB is set to "01" when the time point at which the direction of increase/decrease change in the output shaft torque is first reversed (reversal time point) after the above-mentioned fastening start time point has elapsed.

The above-mentioned reversal point is detected by the process of step 84. In step 84, the magnitude relationship between the output shaft torque T _OUT read in step 71 and the output shaft torque read in the previous process is determined, and a determination is made based on whether or not this magnitude relationship has been reversed. That is, the time when the output shaft torque changes from repeating a monotonous decrease to a monotonous increase is defined as the time of reversal.
This reversal point is like point B' in Figure 6a,
This is the displacement point at which the output shaft torque due to the new gear ratio is reached after point A has passed. From this point of reversal onward, the output shaft torque begins to increase because inertial energy due to rotation is released due to a decrease in the engine output rotation speed due to a decrease in the gear ratio.

When the above-mentioned reversal time point has elapsed, a process of step 85 is performed to increase the pressure data (P _F -ΔP ₁ ), which had been decreased in step 82, by a fixed amount ΔP ₂ . Then, in step 86, the flag
As FB=01, the progress at the time of reversal is memorized.

As a result, at time t _B ′, the duty ratio of the drive signal I is equal to the pressure data (P _F −ΔP ₁ +
The duty ratio is set to generate ΔP ₂ ), and the supply pressure to the friction element starts to rise.

When the reversal time t _B ′ has elapsed, the determination in step 73 becomes YES, and then in the process of step 74,
Pressure data increased in step 85 above (P _F −ΔP ₁
+ΔP ₂ ) is increased by a small amount. That is, by adding the minute increase P ₃ , pressure data (P _F −ΔP ₁ +ΔP ₂ +P ₃ ) is formed.

Then, in step 75, the required shift time _JH , that is, the elapsed time from the engagement start time _tA , is measured, and in the process of step 76, it is determined whether the required shift time _JH has reached the set time _JC . Depending on whether or not the shift operation has been completed, it is determined whether or not the gear shifting operation has been completed.

The above-mentioned setting time J _C is set in advance so that if the friction element remains partially engaged for a long time, it will wear out quickly. Data is stored in memory as a data table.

Therefore, until the end of the shift operation is determined,
The process of step 74 is repeated, each time adding an increment _P3 to the pressure data. As a result, the de-to-tay ratio of the drive signal I gradually increases after the above-mentioned reversal time _tB ' until the shift operation end time _t1 , and along with this, the supply pressure to the friction element also gradually increases.

When the speed change operation is completed, the process of step 77 is performed to change the pressure data to data for bringing the friction elements into a fully engaged state. That is, a pressure command value P that makes the duty ratio of the drive signal I 100% is output.

This completes the gear shifting operation and moves to step 78.
and reset all flags F, FA, and FB.

Through the above processing, the output shaft torque during gear shifting is reduced.
The change in T _OUT is as shown by the broken line T ₁ in FIG. 6a. The change shown by the solid line T ₂ in the figure is the change in the output shaft torque when the duty ratio is kept constant during the gear shifting operation, as shown by the solid line D ₂ in FIG. 6c.

When the duty ratio is kept constant, from the time t _A when the friction element starts to engage, the supply pressure is as shown in Fig. 6b.
Since the output shaft torque T OUT remains constant as shown by the solid line P ₂ in the middle, the rate of change and width of change in the output shaft torque T _OUT are larger than in the case of this embodiment.

In particular, if the change from the first reversal point B after time _tA to the end point P of the release of inertial energy due to the gear ratio change is large and the level at point P is high, it may cause a shift shock.

In contrast, in this embodiment, the supply pressure is once reduced at the start time _tA of fastening, the fastening force at the reversal point B' is weakened, and the supply pressure is gradually increased after the reversal point B'. , the peak value P' of the output shaft torque is significantly reduced, and the occurrence of shift shock can be prevented.

Note that the reason why the supply pressure is once greatly increased at time t _B ' is to improve the responsiveness of the supply pressure increasing operation. By doing this, even if the output shaft torque decreases at time _tQ , this value will be determined by the product of the gear ratio and the input torque of the automatic transmission, and from then on, the output shaft torque will be due to the release of inertial energy again. Although there is an increase, since the fastening force of the friction element is weakened, it is a gradual increase, and the change in the output shaft torque does not become as large as at point R.

Next, the configuration of an embodiment of the second invention is shown in FIG.

As shown in FIG. 7, this embodiment has the same components as the embodiment of the first invention shown in FIG. 25, and a pressure changing section 26 that performs control slightly different from the pressure changing section 24 in FIG.

The timer 25 starts timing from the time when the waveform recognition unit 23 detects the start point of engagement of the friction element during gear shifting, and the timer 25 starts measuring time from the time when the waveform recognition unit 23 detects the time point at which the engagement of the friction element starts at the time of gear change.
Time the TM. However, if the above-mentioned reversal point is detected while counting the time limit TM, the timing operation is stopped and the timing contents are cleared.

The output changing unit 26 changes the supply pressure to the friction element determined according to the reference pressure change set by the pressure determining unit 22 at each arrival of a singular point detected by the waveform recognition unit 23 and by the timer 25. control time
In response to the arrival of the timing end point of TM, an output for forming a drive signal I to be applied to the pressure control valve 40 is generated by changing a predetermined value.

When the control circuit 20B is configured using a microcomputer, the process executed is the fourth one.
Processing substantially similar to the processing in the embodiment of the first invention shown in FIGS. The difference is that steps 91, 92, and 93 are added as shown in FIG.

Therefore, in this embodiment, when the speed change operation is started and the time point at which the friction element starts to engage has elapsed, the timer is started in step 91 along with the supply pressure reduction operation.

Then, the timer continues counting until a reversal point is detected, and the reversal point is detected before the time limit TM is counted, or
When the time limit TM has elapsed, the process of step 85 is performed to increase the supply pressure. At this time, along with setting flag FB=01, step 93
This resets the timer.

By performing such processing, the following effects are achieved.

That is, to explain again using FIG. 6,
After the shift operation starts, the supply pressure to the friction element is reduced from the time point _tA when the engagement of the friction element starts. As the supply pressure decreases, the engagement pressure of the friction element may become too weak, resulting in poor gear shifting operation.

If such a situation occurs, the reversal point B' will not occur, and therefore the timing of increasing the supply pressure will be delayed.

Therefore, as in this embodiment, when the reversal point B' does not occur, the supply pressure is increased from the time limit time TM has elapsed, thereby preventing a shift operation failure from occurring.

Therefore, the above-mentioned time limit TM is set by setting the time corresponding to the time at which the above-mentioned reversal point occurs according to each operating condition and type of shift, and storing the set time data for each of these conditions in the memory as a data table. By doing so, it can be used for the above control.

(Effects of the Invention) As explained in detail above, the first invention detects remarkable change points in the fluctuating waveform of output shaft torque during gear shifting of an automatic transmission, and detects significant change points in response to arrival of these change points. By controlling the supply pressure to the fluid-pressure friction element, the calculation processing is faster than conventional devices that feed back the output shaft torque detection value in real time and compare it with preset torque changes. This can be realized using slow digital circuits.

Additionally, even if error components from the nozzle etc. are mixed into the torque sensor's detection signal, it has little effect on detecting the above-mentioned significant change points, eliminating the need for a high-precision torque sensor and reducing costs. I can figure it out.

Furthermore, select the point at which the friction element starts to engage and the reversal point in the direction of increase/decrease in the output shaft torque as the above-mentioned change points, and at the start of engagement, the supply pressure to the friction element is once lowered, and after the reversal point, the supply pressure is gradually increased. This makes it possible to suppress the output shaft torque fluctuation range and efficiently reduce the occurrence of shift shock.

In addition to the effects of the first invention, the second invention is such that, as a condition for changing the supply pressure, the supply pressure is gradually increased even when a time limit has elapsed from the start of the fastening. When the supply pressure is reduced in response to the arrival of the time to start engaging the friction elements, due to individual differences in automatic transmissions and changes over time in the friction coefficient of the friction elements, the reduction in the supply pressure causes the friction to decrease. Even if the tightening pressure of the element weakens and it becomes difficult to detect when the direction of increase/decrease in the output shaft torque reverses, the supply pressure is gradually increased from the time the above-mentioned time limit has elapsed, thus preventing gear shift operation failures. can.

[Brief explanation of the drawing]

FIG. 1A is a block diagram of the first invention, FIG. 1B is a block diagram of the second invention, FIG. 2 is a block diagram showing the structure of an embodiment of the first invention, and FIG. 2 is a sectional view showing the specific configuration of the pressure control valve, FIGS. 4 and 5 are flowcharts showing the processing executed by the control circuit in FIG. 2, and FIGS. FIG. 7 is a diagram showing changes in the output shaft torque, the supply pressure to the friction element, and the duty ratio of the drive signal during shifting of the automatic transmission controlled by the example, and FIG. 7 shows the configuration of an embodiment of the second invention. Block diagram, Figure 8 is Figure 7
3 is a flowchart showing part of the processing executed by the control circuit shown in the figure. 100... Automatic transmission, 101... Torque sensor, 102... Fastening start time detection means, 103...
... Reversal point detection means, 104 ... Supply pressure control means, 105 ... Fluid pressure friction element, 106 ... Timing means, 107 ... Supply pressure control means, 10 ... Torque sensor, 11 ... Throttle opening sensor, 1
2... Output shaft rotation speed sensor, 20A, 20B...
Control circuit, 40...Pressure control valve, T _OUT ...Output shaft torque, _tA ...Start point of engagement of friction element, tB _'
...At the point of reversal.

Claims (1)

[Claims] 1. A torque sensor that detects the output shaft torque of an automatic transmission; and a torque sensor that configures the automatic transmission when changing gears based on a fluctuation waveform of the output shaft torque detected by the torque sensor. A fastening start point detecting means for detecting a fastening start point of a hydraulic friction element; and a reversal point detecting a point in time when the direction of increase/decrease in output shaft torque is first reversed after the fastening start point of the friction element is detected. a detection means; a period from the fastening start time to the reversal time;
A shift shock reduction device for an automatic transmission, comprising supply pressure control means for reducing the supply pressure to the friction element by a predetermined amount, and then gradually increasing the supply pressure. 2. A torque sensor that detects the output shaft torque of the automatic transmission; and, based on the fluctuating waveform of the output shaft torque detected by the torque sensor, fastening of the hydraulic friction element for shifting that constitutes the automatic transmission during shifting. A fastening start time detection means for detecting a start time; a timing means for counting a predetermined time limit from the start time of the friction element; and after the fastening start time is detected, first:
a reversal point detection means for detecting a point in time when the direction of increase/decrease change in output shaft torque is reversed; 1. A shift shock reduction device for an automatic transmission, comprising supply pressure control means for reducing supply pressure to an element by a predetermined amount and then gradually increasing said supply pressure.