JPH0535781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention can be used in automatic transmissions for vehicles, and in particular relates to an improvement proposal for automatic transmissions aimed at reducing shift shocks. It is.

(Prior Art) Conventional gear shift shock reduction devices for automatic transmissions include, for example, Japanese Patent Laid-Open No. 52-106064 and Japanese Patent Laid-Open No. 106064.
There is something described in the publication No. 53-85264.

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 hydraulic pressure of the hydraulic friction elements used in the transmission.

(Problem to be Solved by the Invention) However, in the conventional device described above, the output shaft torque of the automatic transmission is detected by a torque sensor, and this detection signal is fed back. Since the configuration is such that real-time control is performed in accordance with the torque changes, if the control is performed using a digital calculation circuit such as a microcomputer, an expensive device capable of high-speed calculation is required.

In addition, for real-time control as mentioned above,
When an error component such as noise is mixed into the torque sensor output, control accuracy immediately decreases, and to prevent this, a highly accurate torque sensor, that is, an expensive torque sensor is required.

The present invention determines from the torque waveform of the transmission output torque during a shift whether or not the working fluid pressure of the friction element is appropriate for reducing shift shock, and uses this determination result to operate the friction element during the next shift. The purpose of this study is to solve the above-mentioned problems that have occurred in conventional real-time control by adopting a control method that uses hydraulic pressure determination data.

(Means for Solving the Problems) For this purpose, the shift shock reducing device of the present invention, as conceptually shown in FIG. An output for detecting the output torque of the automatic transmission in an automatic transmission equipped with a hydraulic pressure control means that performs a gear shift and controls the working hydraulic pressure of a friction element during the gear shift to a predetermined hydraulic pressure value for each type of gear shift. a torque detection means 10; a shift detection means 70 for detecting the shift; a torque waveform recognition means 72 which receives signals from these means and recognizes the torque waveform of the transmission output torque during the shift; a hydraulic pressure quality determining means 91 for comparing the certified torque waveform with a reference waveform to determine whether or not the hydraulic pressure of the friction element is appropriate; When it is determined, the configuration is provided with a planned hydraulic pressure value changing means 94 that increases or decreases the planned hydraulic pressure value of the corresponding type of shift so that the inappropriateness can be eliminated.

According to the above configuration, a predetermined shift shock reduction effect is produced as long as the device functions normally. If the pressure source pressure of the automatic transmission fluctuates even temporarily and causes an abnormal drop, or if air gets mixed into the shift control hydraulic circuit and causes the pressure source pressure to drop temporarily, The hydraulic pressure of the friction element also drops abnormally, inevitably causing a large shift shock at the end value of the shift.

The present invention aims to solve this problem as well, and therefore, in addition to the above, the present invention eliminates the response delay from the instant of the shift command to when the friction element actually starts to engage. A gap time measuring means 76 is used to measure the gap time, and the response delay measured by the means is compared with a reference value, and if it is longer than the reference value, the gap time of the friction element is A hydraulic pressure correction means 81 is provided for instructing the hydraulic pressure control means to make the hydraulic pressure higher than the predetermined hydraulic pressure value.

(Function) The hydraulic pressure control means controls the hydraulic pressure of the friction elements to a predetermined hydraulic pressure value for each type of gear change during gear shifting, and the controlled hydraulic pressure selectively operates a plurality of friction elements. This causes the automatic transmission to shift to the corresponding gear.

On the other hand, the gear shift detection means detects the shift in progress, the output torque detection means detects the output torque of the automatic transmission, and the torque waveform recognition means receives the signals from these means and detects the transmission output torque during the shift. Recognize the torque waveform of The hydraulic pressure quality determining means compares the torque waveform recognized by the torque waveform recognition means with a reference waveform to determine whether or not the hydraulic pressure of the friction element is appropriate. When the pressure is determined to be inappropriate, the scheduled hydraulic pressure value changing means increases or decreases the scheduled hydraulic pressure value for the corresponding type of shift so that this inappropriateness is resolved.

Therefore, in the next shift of the same kind, the working hydraulic pressure of the friction element will be controlled to the changed planned hydraulic pressure value, and this will be controlled to reduce the shift shock. I can do it. By the way, according to the configuration of the present invention, which determines the quality of the friction element working hydraulic pressure from the torque waveform of the transmission output torque in the previous time and determines the working hydraulic pressure of the friction element during the next gear shift, it is possible to No calculations are necessary at all, and it becomes possible to use an inexpensive arithmetic circuit, making it possible to reduce the cost of the device and solving the problems of conventional devices that employ a real-time control method.

Furthermore, according to the present invention, since the acceptability of the friction element operating hydraulic pressure is determined by pattern recognition of the torque waveform, even if an error component such as noise enters the output torque detection means for a moment, this is immediately detected. The control accuracy is not deteriorated, and the control accuracy can be kept high, and the torque detection means itself may be inexpensive, and in this respect, the cost of the device can be further reduced.

By the way, the shift shock reduction effect of the above device is effective even if the pressure source pressure of the automatic transmission fluctuates even temporarily and causes an abnormal drop, or if air gets mixed in the shift control hydraulic circuit, the pressure will be reduced even temporarily. When the source pressure drops abnormally, the working fluid pressure of the friction element also drops abnormally, making it impossible to operate the engine, and a large shift shock occurs just before the end of the shift.

In this case, in the present invention, this problem can be solved by the following action. That is, in this case, the so-called response delay time from the shift command measured by the gap time measuring means to the start of engagement of the friction element becomes abnormally long. The hydraulic pressure correction means compares this response delay with a reference value, and detects the above abnormality when the response delay is longer than the reference value. When this abnormality occurs, the hydraulic pressure correcting means instructs the hydraulic pressure control means to make the hydraulic pressure of the friction element higher than the predetermined hydraulic pressure value during the period from the instant when the engagement of the friction element starts until the end of the shift. Therefore, even if the pressure source pressure drops abnormally due to the above-mentioned abnormality, the working fluid pressure of the friction element will not drop abnormally from the time when engagement of the friction element starts until the end of the shift. Even in the event of an abnormality, a predetermined shift shock reduction effect can be guaranteed.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

The configuration of one embodiment of the present invention is shown in FIG.

The control circuit 20 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 it easier to understand.

The information input to the control circuit 20 includes the automatic transmission (not shown) output shaft torque T _OUT detected by the torque sensor (output torque detection means) 10 and the throttle opening detected by the throttle opening sensor 11.
S _TH 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 publication), and the output signal is an analog signal. 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 outputted from the control circuit 20 is a drive signal for the pressure control valve 40 that controls the fluid pressure of the hydraulic friction element that constitutes the transmission mechanism of the automatic transmission.

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 54 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.

Then, from the control circuit 20, the pressure control valve 4
The drive signal I given to 0 is the excitation current of the solenoid valve 52, and this drive signal I is
This is a pulse width modulated current signal output from the PWM circuit (pulse width modulation circuit) 31 in the control circuit 20.

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 changed, 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 20 receives each of 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 28.

The shift point determining unit 21 determines the gear position of the automatic transmission based on the slot opening degree _STH and the output shaft rotational speed _NOUT .

When the gear position is determined by the shift point determining unit 21, the pressure determining unit 22 knows when the gear position changes, that is, when a gear shift is performed, and determines the supply to the hydraulic friction element during this gear shift. A time change in pressure is set in advance (this set time change in supply pressure is referred to as a "reference pressure change").

The waveform recognition unit 25 recognizes a plurality of predetermined singular points in the fluctuating waveform of the output shaft torque T _OUT during gear shifting, and detects the timing of occurrence of these singular points and the output shaft torque T _OUT at that time. do.

The pass/fail determining unit 26 determines whether or not the gear shifting operation causes large torque fluctuations that may cause discomfort to the driver, based on the output shaft torque T _OUT at the singular point detected by the waveform recognition unit 25. do.

The storage section 27 is a memory, and stores the information required for a shift in consideration of the amount of correction of the pressure of the friction element and the wear resistance of the friction element, according to the type of shift, the operating conditions, and the determination result of the previous quality determination section 26. Preset data is stored as a data table so that the allowable amount of time (hereinafter referred to as "allowable shift time") can be determined.

The pressure change correction unit 23 determines the pressure change to be applied to the friction element during gear shifting based on the reference pressure change determined by the pressure determination unit 22 and the pressure correction amount.

The gap time measuring section 24 is connected to the shift point determining section 21.
When the shift gear position is determined and a shift command is issued (this is referred to as the "shift start time _t0 ")
Measure the gap time t _g from to the time when the friction element starts to engage.

The control pressure correction unit 29 corrects the fluid pressure supplied to the friction element to an appropriate value from the time when the engagement of the friction element is started, depending on the length of the gap time t _g .

Next, FIGS. 4 to 6 show that when the control circuit 20 is configured using a microcomputer,
This is a flowchart showing the processing executed by this control circuit 20. The processing shown in FIGS. 4 to 6 is
This is a series of processes that are repeatedly executed at predetermined 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 is "not shifting", when it is "01", it is "shifting", and when it is "10", it is "judging the quality of shifting operation". Show that. Note that when the ignition switch is turned on, the 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 ) have exceeded a shift point that requires a shift.

Here, if the operating conditions do not require a shift, the routine ends without any control. On the other hand, if you need to change gears, step
Processes 66 to 68 are executed.

In step 66, the data of the fluid pressure applied to the fluid pressure type friction element for gear shifting (this is referred to as "pressure data P _A ") is determined by lookup processing of the data table of pressure data stored in the memory. .

The pressure data table (hereinafter referred to as the "pressure data table") includes the type of shift (for example, "shift from 1st to 2nd gear" or "shift from 2nd gear to 3rd gear") and operating conditions (throttle Multiple cases are divided according to the opening degree _STH , output shaft rotation speed _NOUT , vehicle speed, etc.), and the required pressure data under each condition is stored.

In the next step 67, the correction amount ΔP (one correction amount) of the pressure data P _A obtained in step 66 is obtained by lookup processing of the correction amount data table stored in the memory, and this correction is performed. Correct the above pressure data by the amount.

The above correction amount data data table (hereinafter referred to as the "correction amount data table") corresponds to the above pressure data table, and is divided into correction amount data under different conditions depending on the type of shift and operating conditions. ΔP is stored.

In step 68, since it was determined in step 65 that "shifting is required", the flag F is set to "01" to memorize the fact that "shifting is in progress" in order to perform a shifting operation thereafter.

As mentioned above, when flag F=01 is set,
Based on the result of determining the contents of flag F in step 70 of FIG. 5, it is detected that the gear is being shifted (corresponding to gear shift detection means), and then the process of step 71 is executed.
The A/D converter 30 is activated to read data of the output shaft torque T _OUT .

In the next step 72, each time the output shaft torque T _OUT is read in the step 71,
By comparing the output shaft torque read in the previous process, it is possible to recognize multiple predetermined singular points in the fluctuation waveform of the output shaft torque, and to determine when these singular points occur and at that time. The output shaft torque value is stored in a memory area determined by the type of shift and operating conditions (corresponding to torque waveform recognition means).

One of the singular points recognized here is the starting point of engagement of the friction elements, as shown by A ₁ and A ₂ in FIG. 7a. This fastening start point is determined based on the satisfaction of the condition that the value of the output shaft torque T _OUT that is read sequentially decreases a predetermined number of times and the amount of decrease during this period is equal to or greater than a predetermined value.

Also, among the above singular points, other points are as shown in Fig. 7a.
These are the maximum and minimum points of the output shaft torque T _OUT as shown by B ₁ , B ₂ and P ₁ , P ₂ , P ₃ (excluding G).
These singular points are determined by comparing the magnitude of the output shaft torque read in the previous process and the output shaft torque read in the current process, and by reversing the magnitude relationship.

Then, in this step 72, when the above-mentioned fastening start point is recognized, the flag FA is set to "01". This flag FA is a flag for determining that the engagement start point has been recognized, that is, that engagement of the friction elements has started.

Therefore, at time t ₀ in FIG. 7, step 65
If it is determined that "shifting is required" in step 74, the flag FA is "00" until the engagement start point of the friction element is detected, so the determination in step 74 is
The result is NO, and through the process of step 78, the pressure data (P _A + ΔP) obtained and corrected in steps 66 and 67 above is set as the pressure command value P.
It is output to the PWM circuit 31. As a result, a fluid pressure equal to the pressure command value P is supplied to the friction element.

When fluid pressure starts to be supplied to the friction element, the friction plates of the friction element start contacting each other after a while. This point becomes the point at which the friction element starts to be fastened. With this start of engagement, the determination at step 74 becomes YES, and at step 75 the flag FA is set to 10 to memorize the start of engagement, and at step 76 gap time t _g is calculated (corresponding to gap time measuring means). ).

Then, in step 77, it is determined whether or not the gap time t _g exceeds a predetermined reference value, thereby determining whether subsequent correction of the supply pressure is necessary. If the gear shift time t _g is below the reference value, there is no risk of large torque fluctuations (corresponding to the singular point G in Figure 7a) after the shift operation is completed, and the supply pressure to the friction elements is reduced. It is determined that no correction is necessary. If the gap time exceeds the reference value, the supply pressure is too low and the step
81 corrects the pressure command value to be higher (corresponds to hydraulic pressure correction means).

Here, the reason why no correction was made in the case where the supply pressure was too high is that even if the correction was made instantaneously, there would be no effect.

Therefore, if the above supply pressure correction is not necessary,
The pressure data (P _A + ΔP) obtained and corrected in steps 66 and 67 is outputted in step 78 until the completion of the shift operation is determined by the processing in steps 82 and 83, and when the shift operation is completed. , the above pressure data (P _A +
ΔP), pressure data such that the friction element is fixed in a fully engaged state is output as the pressure command value P. That is, a pressure command value P is output such that the duty ratio of the drive signal I is 100% (represented by the duty ratio of ON time). This also ends the actual gear shifting operation.

The process of determining the end of the shift in step 83 is performed by determining the allowable shift time J _C corresponding to the operating conditions from a data table of allowable shift time data stored in memory in advance, and using this J _C and step 82. The completion of the shift is determined by comparing the measured shift time required J _K and whether or not J _K ≧ J _C .

The above-mentioned shift required time _JK is the elapsed time from the time when the above-mentioned frictional element starts to be engaged. Further, the above-mentioned allowable shift time J _C is set for each operating condition in consideration of the wear resistance of the friction elements.

Then, in step 85, the flag F=10 is set to memorize the completion of the shift operation, and in step 86, the flag FA is reset.

When the speed change operation is completed, since the flag F=10, steps 91 to 95 in FIG. 6 are performed.

In step 91, it is determined whether the shift operation performed in the current routine process was performed well without causing a shift shock (corresponding to a means for determining whether the hydraulic pressure is good or bad).

This is done by finding the difference between the minimum value (for example, ₁ point B in Figure 7a) and the maximum value (for example, ₁ point P in Figure 7a) of the singular points recognized in step 72. Let the torque fluctuation width ΔT be the torque fluctuation width ΔT.
It is determined that a good gear shifting operation has been performed when is less than or equal to a reference value.

When it is determined that the torque fluctuation width ΔT is larger than the reference value and a shift shock has occurred, the correction amount ΔP of the supply pressure to the friction element can be changed by the processing in steps 93 and 94. It will be done.

That is, in step 93, in order to reduce the torque fluctuation width ΔT, a pressure correction amount ΔP is set such that the supply pressure to the friction element to be generated during the next shift operation under the same conditions is lower than the current supply pressure. seek.

Then, in step 94, the pressure correction amount ΔP obtained above is inputted into the existing data in the correction amount data table used in step 67 at a position corresponding to the operating conditions and type of speed change during the current speed change operation. A process to change the information is performed. (Equivalent to planned hydraulic pressure value changing means).

As a result, the next time a gear shifting operation is performed under the same conditions as this time, the pressure command value P is formed using the changed pressure correction amount ΔP, thereby reducing the torque fluctuation width ΔT and achieving a good result. It acts to perform a gear shifting operation.

On the other hand, if it is determined that the current shift operation was performed well, the pressure supplied to the friction element was at an appropriate value, and therefore the pressure correction amount is not changed.

Then, in step 95, since the routine process has ended, the supply pressure to the friction element is adjusted by resetting the flag F. This adjustment operation will be explained in more detail.

Assume that the fluctuation pattern of the output shaft torque T _OUT during a certain fluctuation operation is, for example, as shown by the solid line T ₁ in FIG. 7a.

In other words, the gear shifting operation starts from time t ₀ , and
It is assumed that the engagement operation of the friction element starts from t _A1 , and the speed change operation ends at time t ₁ .

The gap time t _g in this case is (t _A1 −t ₀ ), which satisfies the condition that it is equal to or less than the reference value. Therefore, during gear shifting operation, the step
The pressure data obtained in steps 66 and 67 is output as a pressure command value P. Assuming that the duty ratio of the drive signal I at this time is the value shown by _D1 in Fig. 7c,
Assume that the supply pressure is thereby adjusted to the value indicated by P ₁ in FIG. 7b.

In this case, assume that the torque fluctuation width ΔT is (P ₁ −B ₁ ), and this torque fluctuation width is larger than the reference value. Therefore, in steps 93 and 94, the pressure correction amount ΔP is changed.

Then, when a shift operation under the same conditions is performed next time, the pressure command value P is determined using the changed pressure correction amount ΔP. Assume that the duty ratio of the drive signal I at this time is the value shown by _D2 in FIG. 7c.

Here, if the operation is normal, the drive signal I
(Duty ratio is _D2 ) The supply pressure of the friction element generated by this is adjusted to an appropriate pressure that does not cause a shift shock.

However, due to pressure fluctuations in the fluid pressure source and the state of air mixed in the fluid, the broken line in Figure 7b
As shown by P ₂ , the supply pressure to the friction element has decreased more than necessary.

In this case, the engagement action of the friction element becomes significantly slow, so that a situation may occur where the friction element is not completely engaged by the time point t ₁ when the shift operation ends, as shown by the broken line T ₂ in FIG. 7a. be. For this reason, when the fastening pressure is generated by the processing in step 84 at the end of the gear shift operation _t1 , the friction elements are suddenly completely engaged, so that a sudden torque as shown by G in FIG. 7a is generated. There is a risk that fluctuations may occur and shift shock may occur.

Therefore, in this embodiment, when torque fluctuation occurs after the end of the shift as shown by G above,
Since the friction element engagement start time t _A2 is significantly delayed from the shift operation start time t ₀ , the gap time t _g (=
t _A2 −t ₀ ) exceeds the reference value, and from this, an abnormal decrease in the supply pressure is detected.

Then, from the time when an abnormal decrease in the supply pressure is detected (ie, the fastening start time _tA2 ), in step 81, the pressure command value is corrected to increase the supply pressure.
The amount of correction at this time is determined according to the length of the gap time _tg .

As a result, as shown in Fig. 7b and c, the time point
From t _A2 , the duty ratio of drive signal I is from D ₂
D increases to ₃ , and the supply pressure also increases from P ₂ to P ₃ .

Therefore, _the output shaft torque T _OUT becomes as shown by the dashed line T ₃ in FIG. can be prevented.

(Effects of the Invention) As explained above, the present invention determines whether or not the working fluid pressure of the friction element is appropriate for the gear shifting shock from the torque waveform of the transmission output torque during gear shifting, and determines whether or not the hydraulic pressure of the friction element is appropriate for the gear shifting shock. Since the hydraulic pressure is changed to the appropriate value based on the result of this determination, the transmission output torque is detected and feedback is used to control the operating pressure of the friction element in real time so that it reaches the expected value. There is no need for any high-speed calculation that was required in the device, and it becomes possible to use an inexpensive arithmetic circuit, making it possible to reduce the cost of the device.

Furthermore, according to the present invention, since the quality of the friction element operating hydraulic pressure is determined by pattern recognition of the torque waveform, even if an error component such as noise momentarily enters the output torque detection means, this is immediately detected. The control system is not deteriorated, the control accuracy can be kept high, and the torque detecting means itself can be inexpensive, and in this respect, the cost of the device can be further reduced.

By the way, if the pressure source pressure of an automatic transmission fluctuates even temporarily and causes an abnormal drop, or if air gets mixed into the shift control hydraulic circuit and causes an abnormal drop in the pressure source pressure, even temporarily, friction may occur. Since the hydraulic pressure of the element also drops abnormally, the above-mentioned device cannot provide the desired shift shock reduction effect, and a large shift shock occurs just before the end of the shift.However, in the present invention, the friction element is engaged from the shift command. This abnormality is detected when the so-called response delay until the start becomes longer than the reference value, and correction is made to increase the working fluid pressure of the friction element from the moment the engagement of the friction element starts to the end of the shift. .

Therefore, even if the pressure source pressure decreases abnormally due to the above-mentioned abnormality, the working fluid pressure of the friction element will not decrease abnormally from the time when engagement of the friction element is started until the end of the shift. Even at the time of the abnormality, a predetermined shift shock reduction effect can be guaranteed.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the shift shock reducing device of the present invention, Fig. 2 is a block diagram showing the configuration of an embodiment of the present invention, and Fig. 3 is a cross section showing the specific configuration of the pressure control valve in Fig. 2. Figures 4 to 6 are flowcharts showing the processing executed by the control circuit in Figure 2, and Figure 7 is the adjustment operation of the supply pressure of the friction element and the output shaft according to the embodiment shown in Figure 2. FIG. 3 is a diagram showing a state of torque fluctuation. 10...Torque sensor (output torque detection means),
11... Throttle opening sensor, 12... Output shaft rotation speed sensor, 20... Control circuit, 40... Pressure control valve, T _OUT ... Output shaft torque, t _g ... Gap time.

Claims (1)

[Scope of Claims] 1. A gear shift to a corresponding gear stage is performed by selectively hydraulically operating a plurality of friction elements, and the operating hydraulic pressure of the friction elements during the gear shift is set to the planned hydraulic pressure for each type of gear shift. In an automatic transmission equipped with a hydraulic pressure control means for controlling a hydraulic pressure to a specified value, an output torque detection means for detecting an output torque of the automatic transmission, a shift detection means for detecting when the gear is being shifted, and a signal from these means is inputted. a torque waveform recognition means for recognizing the torque waveform of the transmission output torque during gear shifting, and comparing the torque waveform certified by the means with a reference waveform to determine whether or not the working fluid pressure of the friction element is appropriate. A hydraulic pressure determining means for determining whether the hydraulic pressure of the friction element is adequate or not; and when the hydraulic pressure of the friction element is determined to be inappropriate by the means, increasing or decreasing the planned hydraulic pressure value for the corresponding type of gear shift so as to eliminate the inappropriateness. a gap time measuring means for measuring a response delay from the instant of the shift command to when the friction element actually starts to engage; , a hydraulic fluid that instructs the hydraulic pressure control means to make the hydraulic pressure of the friction element higher than the predetermined hydraulic pressure value from the moment the engagement of the friction element starts to the end of the shift. 1. A shift shock reducing device for an automatic transmission, characterized in that it is equipped with a pressure correcting means.