JPH0127301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to a device for reducing shocks during shifting of automatic transmissions, so-called shift shocks.

(2) Prior art An automatic transmission transmits power from the engine to the drive wheels to drive the vehicle, but at this time, it automatically transmits power from the engine to the drive wheels along a scheduled shift line depending on the vehicle speed and engine load (e.g. throttle opening). It is possible to automatically determine a gear position, and to shift up or down to this gear position, thereby driving the vehicle to automatically change gears.

By the way, during gear shifting, especially when shifting up, the shift up is usually done in the so-called power-on state with the accelerator pedal depressed, so it is unavoidable that the gear shifting shock becomes large as explained next. . In this shift shock, the torque of the transmission output shaft normally differs depending on the type of shift up after the ₁ →2 shift up command and the 2→3 shift up command at instants t 1 and t ₂ as shown in FIGS. 15a and 15b. The output shaft torque changes approximately as shown in these figures, and T ₁ and T ₂ (Figures 12 and 14)
This occurs because a higher peak torque is generated (see also the figure). These peak torques are caused by the sudden change in engine speed when the gear stage is changed by upshifting, so that the rotational force, which is the combination of the engine's rotational inertia and the driving force, is rapidly transmitted to the transmission output shaft.

For this reason, a technique has been proposed in which the hydraulic pressure of a friction element that is hydraulically operated at the time of upshifting is set to a target value required to prevent a shift shock during its operation (during gear shifting). As shown, during gear shifting, the hydraulic pressure of the frictional element is maintained at a certain value necessary to prevent gearshift shock, and the rate of increase in the hydraulic pressure is kept small to suppress changes in the torque transmission capacity of the frictional element. There is a known technique for limiting the torque transmitted to the transmission output shaft and reducing the shift shock.

By the way, if the above target value is too high, it will not be possible to sufficiently reduce the shift shock, and if it is too low, the shift will not be completed forever, and the power loss will increase due to excessive slipping of the friction element. The above target values must be appropriate.

However, due to product variations in friction elements, changes over time, etc., the appropriate target value differs from automatic transmission to automatic transmission, and even for the same automatic transmission, it changes over time. However, in the conventional technology, it is not possible to set the target value in consideration of these factors, and the above-mentioned problems cannot be avoided if the target value is too high or too low.

(3) Purpose of the Invention The present invention is based on the fact that product variations in friction elements, changes over time, etc. all appear as changes in the friction element operating oil pressure at the time of the start of engagement. Based on this, a predetermined oil pressure is added to this to determine the working oil pressure of the friction element required to prevent shift shock, and by using this working oil pressure as the target value, it is possible to eliminate product variations and changes over time in the friction element. The objective is to solve the above-mentioned problem in which the target value deviates from the appropriate value due to these variations, changes over time, etc.

(4) Structure of the Invention For this purpose, the shift shock reducing device of the present invention is capable of shifting gears by hydraulically operating a selected friction element, as shown in FIG. In an automatic transmission, the automatic transmission is equipped with a working hydraulic pressure control means that sets the hydraulic pressure to a target value required to prevent shift shock, the working hydraulic pressure detecting means detecting the working hydraulic pressure of the friction element, and the shifting means that detects the start of operation of the friction element. Using the start detection means and the hydraulic pressure at the start of operation of the friction element as a reference, a predetermined hydraulic pressure is added to this to obtain the hydraulic pressure of the friction element required to prevent a shift shock, and this hydraulic pressure is used as the target value. The apparatus is characterized in that it further comprises target operating oil pressure determining means for instructing the operating oil pressure control means.

(5) Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 schematically shows the power transmission portion of a lock-up automatic transmission with three forward speeds and one reverse speed, which is equipped with the shift shock reducing device of the present invention. However, it is clear that the present invention is applicable not only to this automatic transmission but also to any other automatic transmission having a plurality of gear stages.

The power transmission part in Figure 2 is the prime mover (engine).
Crankshaft 4, lockup torque converter 1 with lockup mechanism 17, input shaft 7, front clutch 104, rear clutch 105, second brake 106, low reverse brake 107, one-way brake 10
8, intermediate shaft 109, first planetary gear group 11
0, second planetary gear group 111, output shaft (transmission output shaft) 112, first governor valve 11
3. Consists of a second governor valve 114 and an oil pump 13. The torque converter 1 consists of a pump impeller 3, a turbine impeller 8, a stator impeller 9,
The pump wheel 3 is driven by the crankshaft 4, rotates the torque converter hydraulic oil contained therein, and applies torque to the turbine wheel 8 fixed to the input shaft 7. The torque is further transmitted to the transmission gear train by the input shaft 7. The stator wheel 9 is placed on a fixed sleeve 12 via a one-way clutch 10. One-way clutch 10 connects stator wheel 9 to crankshaft 4
The structure does not allow rotation in the same direction as the arrow, that is, rotation in the direction of the arrow (hereinafter abbreviated as normal rotation). The first planetary gear group 110 includes an internal gear 117 fixed to the intermediate shaft 109 and a hollow conduction shaft 118.
A planetary gear 120 consisting of two or more small gears that can rotate and revolve simultaneously while meshing with each of the sun gear 119, internal gear 117, and sun gear 119 fixed to the output shaft 112.
The second planetary gear group 11 is composed of a planetary gear support 121 that supports a planetary gear 120 fixed to the second planetary gear group 11.
1 is an internal gear 122 fixed to the output shaft 112, a sun gear 123 fixed to the hollow conduction shaft 118, and two or more gears that can rotate and revolve simultaneously while meshing with each of the internal gear 122 and the sun gear 123. It is composed of a planetary gear 124 made of a small gear, and a planetary gear support 125 that supports the planetary gear 124. front clutch 1
04 connects the input shaft 7 driven by the turbine impeller 8 and the hollow transmission shaft 118 which rotates together with both sun gears 119 and 123 via a drum 126, and connects the rear clutch 105
serves to connect the input shaft 7 and the internal gear 117 of the first planetary gear group 110 via the intermediate shaft 109. Second brake 106
is a drum 1 fixed to a hollow conductive shaft 118
By winding and tightening 26, both sun gears 1
19, 123 fixed, low reverse brake 1
07 is the planetary gear support 1 of the second planetary gear group 111
It works to fix 25. One way brake 10
8 has a structure that allows the planetary gear support 125 to rotate in the normal direction but not in the reverse direction. First governor valve 1
13 and a second governor valve 114 are fixed to the output shaft 112 and generate a governor pressure depending on the vehicle speed.

Next, a description will be given of the power transmission train when the speed selection rod is set to the D (forward automatic shifting) position.

In this case, only the rear clutch 105, which is the forward input clutch, is initially engaged. Power from the engine via the torque converter 1 is transmitted from the input shaft 7 to the internal gear 117 of the first planetary gear group 110 through the rear clutch 105. The internal gear 117 rotates the planetary gear 120 in the normal direction. Therefore, the sun gear 119 is reversed and the sun gear 1
The second planetary gear group 11 rotates together with 19.
In order to reverse the first sun gear 123, the planetary gears 124 of the second planetary gear group 111 rotate in the normal direction. One-way brake 108 prevents sun gear 123 from reversing planetary gear support 125 and acts as a forward reaction brake. Therefore, the second planetary gear group 111
The internal gear 122 rotates normally. Therefore, internal gear 1
Output shaft 112 that rotates integrally with 22
The motor also rotates in the normal direction, and the reduction ratio of the first forward speed is obtained. In this state, the vehicle speed increases and the second brake
6 is engaged, power from the input shaft 7 through the rear clutch 105 is transmitted to the internal gear 117 as in the case of the first speed. The second brake 106 fixes the drum 126 and the sun gear 1
19 and acts as a forward reaction force brake. For this reason, the planetary gear 120 revolves around the stationary sun gear 119 while rotating on its own axis, and therefore the planetary gear support 121 and the output shaft 112 integrated therewith are decelerated, but the first gear Normal rotation occurs at a faster speed than in the case of , and the reduction ratio of the second speed is obtained. When the vehicle speed increases further and the second brake 106 is released and the front clutch 104 is engaged, one of the power transmitted to the input shaft 7 is transferred to the rear clutch 10.
5 to the internal gear 117, and the other to the sun gear 119 via the front clutch 104. Therefore, the internal gear 117 and the sun gear 119
are interlocked and rotate forward together with the planetary gear support 121 and the output shaft 112 at the same rotational speed to obtain the third forward speed (gear ratio 1). In this case, the input clutches are the front clutch 104 and the rear clutch 1.
05, and the torque is not increased by the planetary gear, so none of the reaction brakes work.

Next, the power transmission train when the speed selection rod is set to the R (reverse travel) position will be explained.

In this case, the front clutch 104 and low reverse brake 107 are engaged. The power from the engine via the torque converter 1 is transferred from the input shaft 7 to the front clutch 104 to the drum 1.
26 and are guided to sun gears 119 and 123. At this time, since the rear planet carrier 125 is fixed by the low reverse brake 107, the internal gear 122 is decelerated and reversed by the normal rotation of the sun gears 119 and 123, and the output rotates integrally with this internal gear. A retraction reduction ratio is obtained from the shaft 112.

FIG. 3 shows the hydraulic system of the speed change control device related to the automatic transmission, together with the device of the present invention, including the oil pump 13, line pressure adjustment valve 128, pressure increase valve 129, torque converter 1, speed selection valve 130, 1 governor valve 113, 2nd governor valve 114, 1
-2 shift valve 131, 2-3 shift valve 132, throttle pressure reducing valve 138, cut-down valve 134,
Second lock valve 135, 2-3 timing valve 1
36, solenoid downshift valve 137, throttle back up valve 138, vacuum throttle valve 139, vacuum diaphragm 140, front clutch 104, rear clutch 105, second brake 106, servo 141, low reverse brake 107 and hydraulic circuit network. Become.
The oil pump 13 is driven by a prime mover via the crankshaft 4 and the pump impeller 3 of the torque converter 1, and during engine operation always sucks oil from a reservoir 142 through a strainer 143, from which harmful dust has been removed, to a line pressure circuit 144. send out

The oil is regulated to a predetermined pressure by the line pressure regulating valve 128 and is supplied to the torque converter 1 as working oil pressure.
and is sent to the speed selection valve 130. The line pressure regulating valve 128 consists of a spool 172 and a spring 173.
In addition to the spring 173, the throttle pressure of the circuit 165 and the line pressure of the circuit 156 act on the spool 172 through the spool 174 of the pressure booster valve 129, and the force generated by these is applied above the spool 172 from the circuit 144 through the orifice 175. It counteracts the applied line pressure and the pressure applied from circuit 176. The working oil pressure of torque converter 1 is
Oil introduced into the circuit 145 from the circuit 144 via the line pressure regulating valve 128 is introduced into the hydraulic oil inflow passage 50.
After flowing into the torque converter 1, the hydraulic oil is kept within a certain pressure by the pressure holding valve 146 while being discharged through the hydraulic oil outflow passage 51 and the pressure holding valve 146. Above a certain pressure, the pressure holding valve 146 is opened and oil is sent further from the circuit 147 to the rear lubrication section of the drive train. When this lubricating oil pressure is too high, the relief valve 148 opens and the pressure is lowered. On the other hand, lubricating oil is supplied from the circuit 145 to the front lubricating section of the power transmission mechanism by opening the front lubricating valve 149.
The speed selection valve 130 is a manually operated fluid direction switching valve, and is composed of a spool 150, which is connected to a speed selection rod (not shown) via a linkage, and the spool 150 moves with each speed selection operation to change the line. Pressure circuit 14
This is to switch the pressure feeding passage No. 4. The condition shown in FIG. 3 is the N (neutral) position, with line pressure circuit 144 open to ports d and e. The first governor valve 113 and the second governor valve 114 actuate the 1-2 shift valve 131 and the 2-3 shift valve 132 using the governor pressure generated during forward travel to perform an automatic gear change operation, and also control line pressure. When the speed selection valve 130 is in the D and I positions, the oil pressure is applied to the line pressure circuit 1.
44, reaches the second governor valve 114 via port c of the speed selection valve 130, and when the car is running, the governor pressure regulated by the second governor valve 114 is sent to the circuit 157 and then to the first governor valve 113. When the vehicle speed reaches a certain speed, the spool 177 of the first governor valve 113 moves and the circuit 157 becomes the circuit 15.
8, governor pressure is generated, and the governor pressure from circuit 158 acts on each end face of the 1-2 shift valve 131, 2-3 shift valve 132, and cut-down valve 134, pressing each of these valves to the right. Each spring is balanced. Also, speed selection valve 13
A 1-2 shift valve 131 and a second lock valve 135 are separately provided in the middle of the hydraulic circuit that reaches the engagement side hydraulic chamber 169 of the servo 141 that tightens the second brake 106 from the port c of 0 through the circuit 153, circuit 161 and circuit 162. , and further speed selection valve 1
A circuit 152 is provided which reaches the second lock valve 135 from port b of 30.

Therefore, when the speed selection rod is set to the D position, the spool 150 of the speed selection valve 130 moves and the line pressure circuit 1
44 leads to ports a, b and c. Hydraulic pressure flows from port a through circuit 151, and a portion acts on the lower part of second lock valve 135, and spool 178, which is pressed upward by spring 179, receives hydraulic pressure from port b through circuit 152. Rotation 161 conductive by being lowered
and 162 are not cut off, a portion passes through the orifice 166 and reaches the 2-3 shift valve 132 from the circuit 167, and from port c passes through the circuit 153 to the second governor valve 114 and the rear clutch 105.
Then, the transmission reaches the 1-2 shift valve 131 and enters the first forward speed state. In this state, when the vehicle speed reaches a certain speed, the spool 160 of the 1-2 shift valve 131, which is pressed to the right by the spring 159, moves to the left due to the governor pressure of the circuit 158, shifting from the first forward speed to the second forward speed. When automatic gear shifting is performed, circuit 153 and circuit 161 are brought into contact, and hydraulic pressure is transferred from circuit 162 to servo 141 via second lock valve 135.
reaches the engagement side hydraulic chamber 169 of the second brake 1
06 is engaged, and the transmission is in the second forward speed state. In this case, since the 1-2 shift valve 131 is downsized, the speed at the shift point does not increase and the spool 160 moves to the left at the required speed to move forward into the first position.
An automatic shift operation from the first gear to the second gear is performed. When the vehicle speed increases further and reaches a certain speed, the governor pressure of the circuit 158 overcomes the spring 163 and the 2-3 shift valve 1
32 spool 164 to the left and circuit 1
67 and the circuit 168 are connected, and part of the hydraulic pressure from the circuit 168 reaches the release side hydraulic chamber 170 of the servo 141 to release the second brake 106, and part reaches the front clutch 104 and engages it, and the transmission is activated. The vehicle is in the third forward speed.

Furthermore, when the driver depresses the accelerator pedal until the throttle opening is close to full throttle while driving in the D position, desiring a large acceleration force, the kick down switch is turned on and the solenoid downshift valve 137 is activated. Downshift solenoid 13
7a is energized by electricity. As a result, the spool 190 of the solenoid downshift valve 137 is pushed downward by the spring 191 from the upwardly locked position in FIG. At this time, the kickdown circuit 180 that was connected to the circuit 154 is connected to the line pressure circuit 144, and the line pressure is applied to the circuits 144 and 180.
The pressure is supplied to the 1-2 shift valve 131 and the 2-3 shift valve 132 so as to oppose the governor pressure.
At this time, if the vehicle is running in third gear, the spool 164 of the 2-3 shift valve 132 is forcibly pushed by the line pressure from the leftward position to the rightward position against the governor pressure. A forced downshift from third gear to second gear is performed within vehicle speed limits, and sufficient acceleration force is obtained. By the way, if the above-mentioned kickdown is performed while running in second gear, the load is large and the speed is low at this time, so the governor pressure is also low, so the line pressure led to the circuit 180 becomes 1-
The spool 160 of the 2-shift valve 131 is also moved from the leftward position to the right against the governor pressure. Therefore, in this case, a forced downshift from second speed to first speed is performed, and even stronger acceleration corresponding to the heavy load can be obtained.

When the speed selection rod is set to the (second forward speed fixed) position, the spool 150 of the speed selection valve 130 moves and the line pressure circuit 144 communicates with ports b, c, and d.
Hydraulic pressure reaches the same location from ports b and c as in case D and engages the rear clutch 105, while the lower part of the second lock valve 135 is not receiving oil pressure in this case and is connected to circuit 1 of the spool 178.
The areas of the lands above and below the part that opens at 52 and where hydraulic pressure acts are larger at the bottom, so the second lock valve 1
The spool 178 of No. 35 is pushed down against the force of the spring 179, and the circuit 152 and the circuit 162 are brought into conduction, the hydraulic pressure reaches the engagement hydraulic chamber 169 of the servo 141, the second brake 106 is engaged, and the transmission is moved to the second forward position. Be in a state of speed. From port d, hydraulic pressure passes through circuit 154 to solenoid downshift valve 137.
and reaches the throttle backup valve 188. Port a of speed selection valve 130 and line pressure circuit 14
There is a disconnect between circuit 151 and circuit 2-3.
Since the hydraulic pressure has not reached the shift valve 132, the second brake 106 is released and the front clutch 1 is released.
04 is not engaged and the transmission is not in the third forward speed state, and the second lock valve 135 works in conjunction with the speed selection valve 130 to fix the transmission in the second forward speed state. do. When the speed selection rod is set to the I (first forward speed fixed) position, the line pressure circuit 144
leads to ports c, d and e. Hydraulic pressure reaches the same location from ports c and d as in the case of , engaging the rear clutch 105, and from port e via circuit 155 to the 1-2 shift valve 131 to circuit 1.
From 71, a part reaches the low reverse brake 107 and engages the low reverse brake 107, which acts as a forward reaction force brake, putting the transmission in the first forward speed state, and a part goes to the left side of the 1-2 shift valve 131. This acts together with the spring 159 to press the spool 160 to the right, and the first forward speed is fixed.

In addition, as shown in Fig. 2, the torque converter 1
A lock-up mechanism 17 is provided inside, and is controlled by a lock-up control device 100 comprising a lock-up control valve 30 and a lock-up solenoid 31 shown in FIG. 3, and these lock-up mechanism 17 and lock-up control device 100 are well known. However, since it is not related to the present invention, a description thereof will be omitted.

In the present invention, a shift shock reducing device 200 is provided as shown in FIG. 3 to reduce shift shock caused by 2->3 shift up. As is clear from the above, this shift-up speed change is
This is achieved by supplying the line pressure P _L as the front clutch pressure P from the oil passage 168 to the front clutch 104 and operating (fastening) the front clutch. In connection therewith, provision is made to control the front clutch pressure P in a predetermined manner.

As clearly shown in FIG. 4, such a shift shock reducing device includes an orifice 198 in the oil passage 168, and a branch passage 201 with an orifice 199 extending from the oil passage 168 downstream from this. . Note that the branch path 201 is connected to the drain port 2.
02, and a solenoid valve 203 connects and disconnects the two. The electromagnetic valve 203 has a plunger 20 elastically supported by a spring 303a in the closed position shown in the upper half of the figure.
3b, and this plunger is connected to the solenoid 203.
When the valve is electromagnetically attracted to the open position shown in the lower half of the figure by the bias of c, the branch passage 201 is connected to the drain port 202.
shall be communicated to.

The solenoid valve 203 (solenoid 203c) is duty-controlled so as to be energized during the pulse width (on time) of a pulse signal from the computer 204 as shown in FIGS. 5a and 5b. As shown in Figure 5a, when the duty (%) is small, the branch path 20
1 and the drain port 202 is short,
Therefore, as shown in Fig. 6, the front clutch pressure P increases as the solenoid duty decreases.
Finally, it is brought to a maximum value equal to the original pressure, that is, the line pressure P _L. Conversely, as shown in Figure 5b, the duty (%)
When P is large, the communication time between the branch passage 201 and the drain port 202 is long, and therefore the front clutch pressure P
As shown in Fig. 6, as the solenoid duty increases, the
The minimum value determined by the difference in opening area of 99 is set.

The computer 204 for performing the above duty control is driven by a power supply +V, and receives a signal S _p from a pressure sensor 205 that detects the front clutch pressure P, and a signal from a throttle opening sensor 206 that detects the engine throttle opening _TH . S _TH , a signal S _ir from the engine rotation speed sensor 207 that detects the engine rotation speed N _E , and the output rotation speed of the torque converter 1 (the rotation speed of the turbine blade wheel 8 that transmits rotation to the input shaft 7) N _T is detected. Signal from torque converter output rotation speed sensor 208
S _tr , the signal S _0r from the transmission output rotation speed sensor 209 that detects the transmission output rotation speed (rotation speed of the output shaft 112) N ₀ , the gear position (gear stage) of the automatic transmission, and the presence or absence of a shift. , duty control of the electromagnetic valve 203 is performed based on the calculation result of the signal S _s from the shift switch 210 that detects the type of gear change. As the shift switch 210, it is possible to use one constructed by being incorporated into the shift valves 131 and 132, as shown in, for example, Japanese Patent Laid-Open No. 56-127856.

To perform the above duty control, the computer 204 includes, for example, a microprocessor unit (MPU) 24 including a random access memory (RAM), a read-only memory (ROM) 25, and an input/output interface circuit (as shown in FIG. 7). I/O) 22 and analog-digital (A/D)
Converter 27, waveform shaping circuit 28, and amplifier 29
The eighth
It is assumed that the control programs shown in Figures 1 through 11 are executed.

FIG. 8 shows the main routine. When the engine ignition switch is turned on at block 70, the computer 204 starts operating, and at the next block 71, the initial values of the MPU 24 and I/O 26 are set (initialized). It is done. Control then advances to program 72, where MPU 24
is after converting the throttle opening signal _STH from the throttle opening sensor 206 into a digital signal by the A/D converter 27 (however, in this example, the period from throttle fully closed to fully open is divided into eight parts and the digital signal is converted into a digital signal. The throttle opening degree T _H is read through the I/O 26 (assuming that it is quantized). In the next block 73, the MPU 24 is connected to the pressure sensor 205.
The signal S _p from the front clutch is converted into a digital signal by the A/D converter 27 and then read through the I/O 26 to read the front clutch pressure P.

Control then passes to block 74 where the MPU
24 is a signal from the engine rotation speed sensor 207
Based on S _ir , the interrupt routine shown in FIG. 9a is executed as follows to calculate the engine rotational speed N _E. The sensor 207 detects the engine ignition signal and generates a signal S _ir as shown in FIG.
As shown in the figure, a rectangular wave signal S _ir ' rises every time the ignition signal is input. Then, the MPU ₂₄ starts the _interrupt routine shown in FIG. The signal period is calculated from the time difference with the rise of _ir ′.
T _E is measured, and the MPU 24 can calculate the engine rotation speed N _E from this period T _E . Control then proceeds to block 42 where the main routine of FIG. 8 is returned.

In the next block 75 in FIG.
The engine rotational speed N _E (NEW) obtained in , and the engine rotational speed N _E obtained in block 74 one loop before.
(OLD), the change in engine speed during one calculation cycle ΔN _E is calculated as ΔN _E = N _E (OLD) − N _E
Obtained by calculating (NEW). Since the calculation cycle is constant, this ΔN _E can be regarded as the time rate of change of the engine speed. MPU2 in the next block 76
4 calculates the output rotational speed N _T of the torque converter 1 by executing the interrupt routine shown in FIG. 10a as follows based on the signal S _tr from the sensor 208. The sensor 208 is a sine waveform generator that is attached around the input shaft 7 and outputs a signal _Str shown in FIG. The waveform shaper 28 is triggered to produce a rectangular wave signal S _tr ' as shown in FIG. 10b. and MPU
24 starts the interrupt routine of _FIG .
Read S _tr ' via I/O and proceed to the next block 51.
Then, the signal period T _T is measured from the time difference with the previous signal S _tr ', and the MPU 24 can calculate the output rotation speed N _T of the torque converter 1 based on this period. Control then proceeds to block 52 where the main routine of FIG. 8 is returned.

In the next block 77 in FIG. 8, the MPU 24 determines the transmission output rotation speed based on the signal S _pr from the sensor 209.
Calculate N ₀ . Sensor 209 is similar to sensor 208 and is attached to output shaft 112. Therefore, the transmission output rotation speed N ₀ is also MPU
By executing an interrupt routine similar to that shown in FIG. 10a at block 24, the torque converter output rotational speed N _T can be calculated in the same manner as in block 76.

In the next block 78, it is determined whether the shift determiner _S1 is set to 1 or not. In this example, this shift determiner is designed to reduce shift shock 2→
3. This indicates that an upshift is in progress; S ₁ =1 indicates that the shift is in progress; S ₁ =0 indicates that another shift is in progress or not. If S ₁ =1 during 2→3 shift up, control returns to block 72;
The above execution blocks are repeated, but if S ₁ ≠1, and the shift-up is not in progress, control is advanced to blocks 79 and 80 to check whether a new 2→3 shift-up command has been issued. Therefore, in block 79, the shift signal _Ss from the shift switch 210 is read, and in the next block 80, it is determined from this shift signal whether or not a 2→3 shift command has been received, that is, the 2→3 shift valve 132 is in the 3rd gear position. It is determined whether or not the shift-up position is selected.

If there is no 2→3 shift command, block 7
2, and if there is a 2→3 shift command, the control proceeds to block 81 to indicate that the 2→3 shift is in progress at the 2→3 shift command instant t ₂ as shown in FIG.
Set S ₁ =1. In the next block 82, the change in engine speed (ΔN _E ) ₀ during one calculation cycle is read in order to determine the timing at which the front clutch 104 starts to engage (shift start timing), which is the object of the present invention. The reason why the shift start timing can be determined based on this engine speed change (ΔN _E ) ₀ is that the engine speed N _E starts to change suddenly at the shift start time t ₃ as shown in FIG. Since (ΔN _E ) ₀ differs depending on the type of shift (in this case, 2→3 shift) and throttle opening, it is stored in the ROM 25 as table data in advance, and the shift signal S is read in block 79 from this table data. _s (type of gear change) and block 7
It is read out using the table lookup method based on the throttle opening degree T _H read in step 2. In addition, step 8
After execution of step 2, control returns to step 72 and the above-described loop is repeated.

FIG. 11 shows an interrupt routine for performing the control aimed at by the present invention based on the execution results of the control programs shown in FIGS. 8 to 10.
3, it is repeatedly executed by an interrupt signal input from a timer (not shown) at every set time interval ΔT _ns . First, in block 84, the speed change determiner
Depending on whether _S1 is 1 or not, it is determined whether or not the present example is in the middle of a 2->3 shift, which is targeted for shift shock reduction.
If so, the control advances to block 85, and the gear ratio G (1 in this case) corresponding to the shift signal (gear position, in this case 3rd speed) read in block 79.
is read from ROM25, and this and block 77
The torque converter output rotation speed G×N ₀ when the front clutch 104 is completely engaged is calculated by multiplying it by the transmission output rotation speed N ₀ obtained in block 76, and this is calculated as the actual torque converter output rotation speed obtained in block 76. By subtracting it from N _T , that is, by calculating N _T −G·N ₀ , a shift end determination factor F (completion of engagement of front clutch 104) is obtained.

If the front clutch 124 is firmly engaged after the shift has been completed, F=0, but if the front clutch 104 is not yet fully engaged during the shift, F≠0. Furthermore, in an upshift in which the gear ratio G changes from large to small during a shift, F>0, and in a downshift in which the gear ratio G changes from small to large, F<0.

In block 86, it is determined whether the shift end determiner F is positive or negative, and the process proceeds to block 87 only when F>0, that is, an upshift. Since this upshift is a 2 to 3 shift, block 87 is selected only during this shift. . When this shift is completed, F = 0, but the torque converter output rotation speed N _T
There is a possibility that F=0 is not completely achieved due to a slight difference in the detection time of the transmission output rotation speed N ₀ and a calculation error. Therefore, in block 87, when the absolute value |F| of the shift end determiner F becomes less than the set minimum value ε ₁ , it is determined that the shift has been completed, and the control proceeds to block 93, where S ₁ =0. Reset. On the other hand, if |F|≧ε ₁ , that is, if the gear is being changed, control proceeds to block 88.

Block 88 checks whether or not the shift start determiner _S2 is 1, which is 1 if the 2nd to 3rd gear shift has already started due to the start of engagement of the front clutch 104, and 0 if this shift has not yet started. Discern. If it is determined that S ₂ ≠1, it is determined in block 89 whether or not a new shift from 2 to 3 has started. In making this determination, at the start of the shift (instant t ₃ in FIG. 12), as described above, the engine speed change ΔN _E in block 75 exceeds the engine speed change (ΔN _E ) ₀ for determining the shift start timing in block 82. Therefore, it is determined that the 2 to 3 gear shift has started due to the start of engagement of the front clutch 104.

When the gear shift is started, block 89 selects block 89', and the front clutch pressure at this time is
Read P ₁ (see Figure 12) and proceed to the next block 90.
Then, a correction value P ₀ for the above-mentioned pressure P ₁ of the front clutch pressure (fastening force of the front clutch 104) necessary to prevent the 2->3 shift shock is read from the ROM 25. This correction value P ₀ is stored in the ROM 25 in advance as table data of the type of shift (in this case, 2→3 shift) determined by reading the shift signal S _s and the throttle opening TH read as described above. , read out using the table lookup method. In this example, the correction value _P0 is fixed at the read value, but it can be gradually increased as the shift progresses as long as a shift shock does not occur.

In the next block 91, the target value P _ain of the front clutch pressure to be maintained to prevent gear shift shock is set as P _ain =
It is determined by P ₁ +P ₀ , and then in block 92 the shift start determiner S ₂ is set to S ₂ =1. Next, control proceeds to block 96, but once S ₂ =1 is set, block 88 selects block 96, and thereafter blocks 89 and 8 are selected until the next 2→3 shift.
9', 90-92 are not selected.

In block 96, the difference ΔP between the actual value P of the front clutch pressure and the target pressure P _ain is calculated. In the next block 97, it is determined whether ΔP>0 or not. If ΔP>0, that is, P>P _ain . If the control is block 9
Proceed to step 9, perform the calculation in the direction of increasing the output duty as Duty (NEW) = Duty (OLD) + K・ΔP, and apply the calculation result Duty (NEW) to the next block 100.
Replace with Duty (OLD). and block 1
At 01, Duty (NEW) is set as the output duty and is output to the solenoid valve 203 via the amplifier 29 in FIG. Note that Duty (NEW) is the output duty to be newly updated, Duty (OLD) is the current output duty, and feedback coefficient K is a constant value. Of course, it is also possible to make the feedback coefficient K a function of the pressure difference ΔN. As shown in FIG. 6, as the output duty increases, the front clutch pressure becomes lower, so that the front clutch pressure P can be brought closer to the target pressure P _ain by correcting P>P _ain .

On the other hand, if the determination result of block 97 is ΔP〓0, that is, if P<P _ain , control is passed to block 96.
Then proceed to block 98. In block 98, a calculation is performed in the direction of decreasing the output duty as Duty (NEW) = Duty (OLD) - K・ΔP, and as a result, Duty (NEW) is set to the next block 100, 1.
01, and is output to the solenoid valve 203 as in the case of ΔP>0 described above. In this case as well, as shown in Fig. 6, the front clutch pressure P is increased by reducing the output duty, and the front clutch pressure P can be brought closer to the target pressure P _ain by correcting P<P _ain . I can do it.

Thus, as shown in FIG. 12, the front clutch pressure P is maintained at the target value P ain from the shift start instant t ₃ after the shift command instant t ₂ to the shift end instant t ₄ during the 2→3 shift, and the front clutch pressure P is maintained at the target value P _ain . The torque transmission capacity of the clutch 104 can be kept constant. Therefore, when shifting from 2 to 3, the combined rotational force of the engine's inertia and driving force is transmitted to the transmission output shaft at a constant rate, and the engine rotation speed N _E is proportional to the transmission output rotation speed N ₀ . In addition to changing the torque as shown by the solid line in Figure 12, the transmission output shaft torque could be made as shown by the solid line in Figure 12, and the peak torque that was generated because these were respectively as shown by the dotted line in Figure 12. It is possible to reliably reduce the 2→3 shift shock caused by T ₂ (explained with reference to FIG. 15b).

In determining the target value P _ain , the front clutch pressure P ₁ at the start of gear shifting is used as a reference, and the front clutch pressure P ain required to reduce the engine speed N _E at a predetermined rate of change over a predetermined period of time necessary to prevent gear shifting shock is determined. In order to obtain the torque transmission capacity of the clutch 104, the above
Since the target value P _ain is the value obtained by adding the correction value P ₀ to P ₁ , even if there are product variations or changes over time in the front clutch 104, these will result in changes in the front clutch pressure P ₁ at the start of gear shifting. This is taken into account in determining the target value, and this target value can always be set to the optimum value without being affected by variations or changes over time in the front clutch 104, thereby preventing excessive slippage of the front clutch (early wear and power loss). It is possible to reliably prevent a shift shock without causing a problem.

In the above example, the target value P _ain is fixed during the shift, but it is also possible to set P _ain as an initial value and slightly change it during the shift by changing P ₀ as described above.

By the way, in FIG. 11, when the block 84 determines that S ₁ ≠ 1, that is, when it determines that there is no 2→3 shift command, and when the block 86 determines that F<0, that is, F
>0 and it is determined that the shift is a downshift shift, the above-mentioned control that is the object of the present invention is not necessary, so the control proceeds to block 94 in the same way as after execution of block 93, and the shift start determiner S ₂ is reset to zero, and control then passes to block 95. Block 95 sets the output duty to 0%,
At this output duty of 0%, as shown in FIG. 6, the front clutch pressure P is set to the line pressure P _L itself, and the operation control of the front clutch 104 is left to the variable control hydraulic circuit shown in FIG. 3. This block 95 is executed before the shift starts (t ₂ to _{t 3} in FIG. 12) when the block 89 determines that ΔN _E >(ΔN _E ) is _not
It is also carried out during the period).

Control then proceeds from block 95 or 101 to block 102, where it returns to the main routine of FIG. 8, and the above-described control is repeated.

FIG. 13 shows another example of the present invention, and this example is 1→
It is constructed to reduce the shift shock associated with 2nd shift up. As is clear from the above, this shift-up transmission
62 to second brake 106 operating servo 1
This is achieved by supplying the line pressure P _L as the second brake operating pressure P to the engagement side oil passage 169 of 41 and operating the second brake 106.
00 is provided in association with the oil passage 162, thereby making it possible to control the second brake operating pressure P in a predetermined manner.

For this purpose, the computer 204 in this example also executes the same control program as shown in FIGS. Block 73 changes the front clutch pressure P to second brake operating pressure P, changes the shift determiner _S1 in blocks 78 and 81 to indicate that a 1→2 shift command has been received, and changes 2→3 in block 80. The shift command is changed from 1 to 2 shift command, and the block 82 is changed to read the engine rotational speed change (ΔN _E ) ₀ for determining the time to start applying the second brake (shifting). Also in Figure 11, block 8
The shift determiner _S1 of blocks 88, 92, and 94 is changed to the same one as described above, and the shift start determiner _S2 of blocks 88, 92, and 94 indicates that the 1st to 2nd shift is started when the second brake 106 starts to be engaged. We will change it to something that shows that.

Thus, as shown in FIG. 14, the second brake operating pressure P remains at the target value during the 1st to _2nd shift from the shift start instant t3' after the shift command instant _t1 to the shift end instant _t4 '.
The torque transmission capacity of the second brake 106 can be kept _constant . Therefore, 1
→When shifting to 2nd gear, the rotational force that is the combination _of engine inertia and driving force is transmitted to the transmission output shaft at a constant _rate . At the same time, the transmission output shaft torque can be changed as shown by the solid line in the same figure, and the peak torque T ₁ (Fig. 5 a 1→2 due to
The shift shock can be reduced in the same way as the 2→3 shift shock.

In addition, since the target value P _ain is determined by adding P ₀ to the second brake operating pressure P ₁ at the start of gear shifting, the second brake 106
Even if there are variations in the product or changes over time, the target value can always be set to the optimum value without being affected by these, and the same effect as in the case of 2→3 shifting described above can be achieved.

In addition, in all of the above-mentioned examples, the structure was configured to reduce the shift shock during up-shifting (2->3 shifting, 1->2 shifting), but when downshifting (3->2 shifting).
2, 2 → 1) Regarding the shift shock when shifting,
It goes without saying that by applying the present invention based on the same concept, these problems can be reliably reduced and the same effects as described above can be achieved.

(6) Effects of the Invention As described above, the shift shock reducing device of the present invention has the friction element 10 necessary for preventing shift shock.
The working oil pressure target value P _ain of 4,106 is determined based on the working oil pressure P ₁ at the start of gear shifting, that is, the value obtained by adding a predetermined amount P ₀ to this P ₁ is set as the target value P _ain .
Even if there are product variations or changes over time in the friction elements mentioned above, the target value P _ain will always be an appropriate value that takes these factors into account, and the target value will be too high to achieve sufficient reduction of shift shock. , it is possible to reliably eliminate problems where the target value is too low, causing power loss and early wear due to gear shift delays and excessive slipping of the friction elements.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing the shift shock reducing device of the present invention, Fig. 2 is a skeleton diagram showing the power transmission section of an automatic transmission equipped with the device of the present invention, and Fig. 3 is a shift control hydraulic circuit of the automatic transmission. 4 is a system diagram of the device of the present invention, FIGS. 5a and 5b are time charts showing changes in duty output by the computer of the device, and FIG. 6 is a change in front clutch pressure with respect to duty. FIG. 7 is a block diagram of the computer, FIGS. 8, 9a, and 10a are flowcharts of the control program executed by the computer, and FIGS. 9b and 10b are the engine block diagrams. An explanatory diagram of waveforms before and after waveform shaping of the rotational speed signal and the torque converter output rotational speed signal, FIG. 11 is a flowchart of the control program executed by the computer, FIG. 12 is an operation time chart of the device of the present invention, and FIG. FIG. 14 is a system diagram similar to FIG. 4 showing another application example of the invention device, FIG. 14 is an operation time chart of the invention device in the same application example, and FIGS.
This is an operation time chart showing the occurrence of a shift shock during a 2nd shift and a 2→3 shift. 24...Microprocessor unit, 25...Read-only memory, 26...I/O interface circuit, 27...A/D converter, 28...Waveform shaping circuit,
29...Amplifier, 104, 106...Friction element (10
4...front clutch, 106...second brake), 198, 199...orifice, 200...speed change shock reducing device of the present invention, 201...branch road, 2
02...Drain port, 203...Solenoid valve, 204...
Control computer, 205...pressure sensor (operating oil pressure detection means), 206...throttle opening sensor,
207... Engine rotation speed sensor, 208... Torque converter output rotation speed sensor, 209... Transmission output rotation speed sensor, 210... Shift switch.

Claims (1)

[Scope of Claims] 1. An automatic transmission capable of changing gears by hydraulically operating a selected friction element, and equipped with hydraulic pressure control means that sets the hydraulic pressure to a target value required to prevent gear shifting shock while the friction element is in operation. In the transmission, a working oil pressure detecting means for detecting the working oil pressure of the friction element, a shift start detecting means for detecting the start of operation of the friction element, and a predetermined hydraulic pressure based on the working oil pressure at the time of starting the operation of the friction element. A target operating oil pressure determining means is provided, which calculates the operating oil pressure of the friction element required to prevent shift shock by adding the oil pressures, and instructs the operating oil pressure control means to use this operating oil pressure as the target value. Gear shift shock reduction device for automatic transmission. 2. The shift shock reduction device for an automatic transmission according to claim 1, wherein the target operating oil pressure determining means changes the predetermined oil pressure depending on the type of shift and the engine load.