JPS639759A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a shock due to a fact that a line pressure is excessively higher than an engine output, by a method wherein correction control is effected in a manner that, by means of a line pressure correcting means, a line pressure set by a line pressure set means is decreased over that during running on lowlands. CONSTITUTION:In a pressure regulating valve 52, a bellows 91 is positioned to the end face on the pressure reducing port 52d side of a spool 52' through the force of a spring 92. When an atmospheric pressure is low, the bellows 91 is expanded to press the spool 52' in a direction, in which a drain port 52e is opened, through the force of the spring 92. Thereby, a line pressure to a specified boost pressure is set to a value lower than that during running at lowlands, characteristics of the line pressure to the boost pressure are also decreased generally. Thus, even during running at highlands in that an engine output is decreased, during transmission of an automatic transmission gear, a line pressure fed to a hydraulic actuator is adapted for torque or an engine output, being to be transmitted to a clutch or a brake, and a high transmission shock caused due to a fact that a line pressure is excessive is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic control device for an automatic transmission that is installed in an automobile and automatically changes gears according to the operating conditions of the FF1JI vehicle and the engine. .

(Prior Art) Generally, an automatic transmission is configured to combine a torque converter and a speed change gear mechanism, and obtain a plurality of gears by switching the power transmission path of the speed change gear mechanism. Control of this gear stage involves friction members such as clutches and brakes that change the coupling relationship of each component of the gear tooth mechanism, a plurality of hydraulic actuators that actuate each of these friction members, and hydraulic pressure applied to these actuators. This is done by a hydraulic circuit that controls the supply and discharge, and the hydraulic circuit supplies /! through the hydraulic pressure 7 cutuator according to the operating conditions of the vehicle and engine. By selectively fastening the friction members, the power transmission path of the gear tooth structure, that is, the gear stage, can be switched.

In that case, the hydraulic circuit is configured to perform gear shift control based on a preset shift pattern using, for example, vehicle speed and engine load as parameters; According to the Japanese Patent Application Publication No. 2003-11902, a system is disclosed in which this shift pattern is changed depending on the altitude position of the vehicle. This is to deal with the problem that acceleration performance deteriorates when driving at high altitudes (for example, when the engine output is low) if the shift pattern is fixed, since the engine output changes depending on the altitude position (in other words, the atmospheric pressure). When driving at high altitudes, if the shift pattern is changed so that the vehicle speed at which upshifting is performed is shifted to a higher vehicle speed side, desired acceleration performance can be obtained.

On the other hand, in this type of automatic transmission, line pressure ill control is performed in which the oil pressure (line pressure) supplied from the hydraulic circuit to the hydraulic actuator is set in accordance with the engine output. This is in response to the fact that the torque transmitted through the friction member varies depending on the engine output.
The torque capacity of one member increases or decreases, and this causes shock during fastening due to the friction member's torque capacity (line pressure) being too large relative to the transmitted torque, or shock during fastening due to the friction member's torque capacity (line pressure) being too small compared to the transmitted torque. This prevents problems such as slippage.

(Problems to be Solved by the Invention) By the way, in the above-mentioned line pressure control, the opening degree of the throttle valve provided in the intake passage of the engine, the boost pressure downstream of the throttle valve in the intake passage, etc. are used as the engine output. When the opening degree is large or the boost pressure is high, that is, when the engine output is large, the line pressure is controlled to be increased. Problems like this can occur. In other words, when driving at high altitudes, the atmospheric pressure or air density is low, so even if the throttle valve opening or boost pressure is constant, the combustion rate of the engine is lower than when driving at low altitudes where atmospheric pressure is high. The air charge is reduced and the engine output is reduced. As a result, the line pressure, which is set according to the throttle valve opening or boost pressure, becomes higher relative to the engine output than when driving at low altitudes, and as a result, a large shift shock occurs when the automatic transmission shifts. I will do it.

The invention described in the above publication changes the gear shift pattern depending on the altitude position, and since the line pressure characteristics do not change between driving at low altitudes and driving at high altitudes, even if this invention is adopted, The problem of increased shift shock when driving at high altitudes remains unresolved.

The present invention addresses the above-mentioned problems in automatic transmissions, and the line pressure supplied to the hydraulic actuator becomes high relative to the engine output when the vehicle is traveling at high altitudes, resulting in large gear changes. The purpose is to prevent problems such as shock.

(Means for Solving the Problems) In order to achieve the above object, a hydraulic control device for an automatic transmission according to the present invention is characterized in that it is configured as follows.

As shown in FIG. 1, the automatic transmission mA consists of a torque converter C connected to an engine output shaft B, a transmission gear mechanism disposed on the output side of the torque converter C, and the power of the transmission gear mechanism. A plurality of FJ friction members E...E that change the transmission path to obtain a plurality of gears, and these fll! Hydraulic actuator F to actuate member E, respectively.
...F, and a hydraulic circuit G that controls the supply and discharge of hydraulic pressure (line pressure) to and from these actuators F...F, and the hydraulic circuit G includes a line pressure setting that sets the line pressure. Foot means are provided.

This line pressure setting means H controls each hydraulic actuator F according to, for example, the opening degree of a throttle valve (not shown) provided in the intake passage of the engine or the boost pressure downstream of the throttle valve in the intake passage. ...Set the line pressure supplied to F, and each actuator F...
It serves to adapt the torque capacity l of the friction members E... corresponding to F to the torque transmitted by these am members E...E.

In addition to the above configuration, this automatic transmission A includes:
A line pressure correction means I is provided which operates according to the atmospheric pressure to lower the line pressure set by the line pressure setting means H when the atmospheric pressure is low.

(Function) According to the above configuration, when the atmospheric pressure is relatively high, the required intake air filling amount is secured, and the engine output is not reduced when driving at low altitudes, the engine output is controlled by the line pressure setting means H. The line pressure is set to match. Therefore, by supplying this line pressure from the hydraulic circuit G to the hydraulic actuators F...F, the friction members E...E
When ftJ is selectively tightened, a large shift shock due to excessive line pressure is prevented from occurring, and after tightening, slipping of ftJ friction members E...E due to insufficient line pressure is prevented. This will be prevented.

On the other hand, when driving at high altitudes where atmospheric pressure is low, the intake air filling volume decreases and the engine output decreases, the line pressure setting means H adjusts the engine throttle valve opening, boost pressure, etc. in the same way as when driving at low altitudes. When the line pressure is set using the engine output, the line pressure becomes relatively large with respect to the engine output. Since correction control is performed to lower the line pressure, the line pressure is adjusted to the engine output in this case as well, and a large shift shock due to the line pressure being relatively excessive with respect to the engine output is avoided. This will be prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows the mechanical structure and hydraulic circuit of the automatic transmission 1, which includes a torque converter 10
, a multi-speed gear mechanism 20, and an overdrive gear mechanism 40 disposed between the two.

The torque converter 10 includes a pump 13 directly connected to the output shaft 3 of the engine 2 via a drive plate 11 and a case 12, a turbine 14 disposed in the case 12 to face the pump 13, and the pump 13. The stator 15 is disposed between the turbine 14 and the turbine 14, and an output shaft 16 is coupled to the turbine 14. Further, a lock-up clutch 17 is provided between the output shaft 16 and the case 12. This lock-up clutch 17 is constantly pressed in the tightening direction by the pressure of the hydraulic oil circulating inside the torque converter 10, and the release chamber 1
It is released when hydraulic pressure is supplied to 8.

The multi-speed gear mechanism 20 includes a front planetary gear mechanism 21 and a rear planetary gear mechanism 22, and sun gears 23, 24 of both mechanisms 21, 22 are connected by a connecting shaft 25. The input shaft 26 to this multi-speed gear mechanism 20 is
The connecting shaft 25 is configured to be connected to the connecting shaft 25 via the front clutch 27, and to the one ring gear 29 of the front planetary gear open groove 21 via the rear clutch 28, and the connecting shaft 25, that is, both planetary gear mechanisms. A second brake 31 is provided between the sun gear 23.24 and the transmission case 30 at 21.22. front 31
The binion carrier 32 of the first gear mechanism 21 and the ring gear 33 of the rear planetary gear mechanism 22 are connected to the output shaft 34,
Furthermore, a low reverse brake 3 is provided between the binion carrier 35 of the rear planetary gear mechanism 22 and the transmission case 3o.
6 and a one-way clutch 37 are provided in parallel.

On the other hand, in the planetary gear mechanism constituting the overdrive speed change gear mechanism 40, a binion carrier 41 is connected to the output shaft 16 of the torque converter 10, and a sun gear 42 and a ring gear 43 are connected by a direct clutch 44. It is said that In addition, the sun gear 42
An overdrive brake 45 is provided between the transmission case 30 and the transmission case 30, and the ring gear 43 is connected to the input shaft 26 to the multi-speed gear mechanism 20.

The power transmission paths of the multi-speed gear mechanism 20 and the overdrive gear mechanism 40 are switched by selectively operating the clutches 27, 28, 44, brakes 31°, 36,45, and one-way clutch 37, As a result, four forward speeds and one reverse speed are obtained between the input shaft (torque converter output shaft) 16 and the output shaft 34.

In addition, in each range selected by the manual valve of the hydraulic circuit described below, the relationship between the operation of each clutch and brake and the gear position is as shown in Table 1.

(Hereinafter, blank spaces) Next, the configuration of the hydraulic circuit in the automatic transmission 1 will be described.

This hydraulic circuit 50 is equipped with a wheel pump 51 that is constantly driven by the engine output shaft 3 (torque converter case 12), and from the pump 51 to the discharge line 10.
1 is introduced into the pressure regulating boat 52a of the pressure regulating valve 52 via the pressure regulating line 102, the hydraulic pressure of the hydraulic fluid is adjusted to a predetermined line pressure, and this line pressure is led to the manual valve 53 via the input line 103. This manual valve 53 is provided with each range of P, R, N, D, and 2.1, and in each of these ranges, five ports a-- are selectively communicated with the input line 103. et
fi is provided. That is, D.

2. A port a that communicates with the input line 103 in each range of 1, and the line 103 in each range of D and 2.
and the line 10 in the R range.
Boats C and P connected to 3.

A boat d communicates with the line 103 in each range of R, 2, 1, and a boat d that communicates with the line 103 in each range of R, 1.
A boat e is provided which communicates with 3. First to fifth line pressure lines 111, 112, 113, 114, and 115 are connected to these boats a to 8, respectively.

From the first line pressure line 111, the first to
The third control line 121, 122, 123 is branched, and the first control line 121 is connected to the orifice 121'.
The second control line 122 connects to the orifice 122 at the right end of the 1-2 shift valve 610 in the drawing (hereinafter the same).
The third control line 123 is led to the right end of the 2-3 shift valve 62 through an orifice 123', and the third control line 123 is led to the right end of the 3-4 shift valve 63 through an orifice 123'. In addition, drain lines 121'', 122'', 123'' are connected between each orifice 121', 122', 123' in these control lines 121, 122, 123 and each shift valve 61, 62, 63, respectively. These drain lines 121'' are branched.

First to third shift solenoid valves 71, 72, and 73 are provided to open and close 122'' and 123'', respectively.

These solenoid valves 71, 72, 73 are respectively
Drain lines 121", 12 corresponding to ON (excitation)
2", 123" and close the control lines 121, 12.
A control pressure is generated within 2.123, thereby moving each of the shift valves 61.62.63 from the OFF position shown in the figure to the ON position on the left side. and,
The combination of ON and OFF of these solenoid valves 71 to 73, that is, the ON position and OFF of the shift pulps 61 to 63
In combination with the F position, each gear stage can be obtained as shown in Table 2.

(The following is a blank space) Table 2 Note that the third solenoid valve 73 is turned OFF during 1st and 2nd speeds in the D range, but when in 1st and 2nd speeds in the Lunge and 2nd ranges, the values shown in Table 2 above are OFF. As shown in parentheses, each is turned on. This is because by turning on the third solenoid valve 73 in the lunge and second ranges, hydraulic pressure is supplied to the backup control valve 81, which will be described later, via a line 131 branched from the third control line 123.

And the first to third solenoid valves 71 to 71 as described above.
By the operation of each of the shift valves 61 to 63 as the shift valve 73 is turned on and off, line pressure is supplied to each clutch and brake so that the gear positions shown in Table 1 above are obtained.

That is, when the 1-2 shift valve 61 is in the OFF position, the fifth line pressure line 115 connected to the boat e of the manual valve 53 is communicated with the low reverse brake line 132 via the shift valve 61. . Therefore, in the lunge and R ranges where the boat e is connected to the input line 103, line pressure is supplied to the actuator 36a of the low reverse brake 36, thereby engaging the low reverse brake 36. When this 1-2 shift valve 61 moves to the ON position, the fifth line pressure line 115 and the low reverse brake line 132 are cut off, and the first line pressure line 111 connected to boat a is branched off. A line 134 led to the left end of the 1-2 shift valve 61 via a line 133 is connected to a second brake engagement line 135, and the line 135 connects the one-way orifice 135.
' through the actuator 31 of the second brake 31
Line pressure is introduced to the fastening side boat 31a' at point a. As a result, the boat a is connected to the input line 103, and 2. 1-2 shift valve 6 in lungi
1 moves to the ON position, the second brake 31 is engaged. Note that the one-way orifice 135 in this second brake engagement line 135
An accumulator 135'' is provided downstream of the accumulator 135'', and a line 136 further branched from the branch line 133 of the first line pressure line 111 is led to the accumulator 135''. A reducing valve 82 is installed to control the supply of back pressure to 135''.

Further, the branch line 13 of the first line pressure line 111 is
A rear clutch line 137 is branched from the rear clutch line 137, and line pressure is introduced from the line 137 to the 7-cut actuator 28a of the rear clutch 28 via a one-way orifice 137'. As a result, D.2.
During the lunge, the spring clutch 28 is always engaged. The rear clutch line 137 is also provided with an accumulator 137'' to which back pressure is supplied by a line 138 branched from the branch line 133.

Next, to the 2-3 shift valve 62, a second line pressure line 112 is connected to the boat b of the manual valve 53 and introduces line pressure in the D and 2 ranges, and a second line pressure line 112 is led to the boat C. A third line pressure line 113 connected to which line pressure is introduced in the R range is also led to the 2-3 shift valve 62 via a one-way orifice 113' and a reducing valve 83 arranged in parallel. . When the shift valve 62 moves to the ON position, the second line pressure line 112 is connected to the front clutch line 139, and when the valve 62 is in the OFF position 2, the third line pressure line 113 is connected to the front clutch line 139. are selectively communicated with. This front clutch line 139 introduces line pressure to the actuator 27a of the front clutch 27 through a one-way orifice 139', thereby causing 2-3 in the D range.
The front clutch 27 is engaged when the shift valve 62 moves to the ON position and when the shift valve 62 is in the OFF position in the R range.

Further, from the front clutch line 139, the release side boat 3 of the second brake actuator 31a is connected via one-way orifices 140', 140''.
1A” second brake release line 140
is branched, and therefore, when the front clutch 27 is engaged, the second brake 31 is released. Incidentally, an accumulator 139'' is connected to the front clutch line 139 via a one-way orifice 139'' to which back pressure is supplied via a line 141 branched from the upstream portion of the line 13.

Further, from the second brake release line 140, 3
A line 142 leading to the -2 timing valve 84 is branched. The 3-2 timing valve 84 is moved to the right by the control pressure supplied to its left end, and is connected to the second brake release line 14 via the line 142.
The line 143 that supplies the control pressure to the valve 84 is connected to the first line pressure line 11.
The drain line 133'' is connected to the first branch line 133 via an orifice 133', and a drain line 133'' whose opening and closing are controlled by a timing adjustment solenoid valve 74 is branched downstream of the orifice 133'.

Therefore, the supply of the control pressure is controlled by this solenoid valve 74, and accordingly, the operation timing of the 3-2 timing valve 84 is determined, that is, the second brake release line 140 is drained, and the second brake 31 is engaged. Timing is now optimally controlled.

Further, a sixth line pressure line 116 directly branched from the pump discharge line 101 without going through the manual valve 53 is led to the 3-4 shift valve 63 . This line 116 indicates that the 3-4 shift valve 63 is on the right side.
When in the FFFF position, it is communicated with the direct coupling clutch line 144 and reaches the actuator 44a of the direct coupling clutch 44 via the one-way orifice 144', and the inlet 145 branched from the direct coupling clutch line 144 is connected to the actuator 45a of the overdrive brake 45. is guided to the release side boat 45a'' at 3.
-4 When the shift valve 63 is in the OFF position, the direct coupling clutch 44 is engaged and the overdrive brake 4
5 is released.

When the 3-4 shift valve 63 moves to the left ON position, the direct coupling clutch actuator 44a
Then, the supply of hydraulic pressure to the release side boat 45a'' of the overdrive brake actuator 45a is cut off.
At this time, overdrive brake actuator 4
Since line pressure is constantly supplied to the engagement side boat 458' of 5a from the pump discharge line 101, the overdrive brake 45 is engaged.

Here, this 3-4 shift valve 63 has a fourth line pressure line 1 connected to the boat d of the manual valve 53.
14 is introduced, and in ranges other than the D range, the line pressure introduced from this line 114 prevents the 3-4 shift valve 63 from moving to the ON position. The direct clutch line 144 is equipped with an oil pressure sensor 144'' and an accumulator 1441 to which back pressure is supplied from the pump discharge line 101.

On the other hand, a pressure regulating line 102 branched from the pump discharge line 101 and reaching the pressure regulating valve 52 is connected to the pressure regulating valve 52.
The line 14 is connected to the torque converter line 146 via the torque converter pressure adjustment boat 52b of No. 2.
6 is led into the torque converter 10. Further, a line 147 branched from this line 146 is led to a lock-up valve 85, and from the lock-up valve 85, hydraulic pressure is introduced into the release chamber 18 of the lock-up clutch 17 in the torque converter 10. Lock-up release line 1 for releasing the clutch 17
48 is being led. A lock-up control line 149 branched from the pump discharge line 101 is led to the sixth valve of the lock-up valve 85 via an orifice 149', and a drain line is provided downstream of the orifice 149'. 149'' is provided with a lock-up control solenoid valve 75. When turned on, this solenoid valve 75 connects the drain line 149.
By closing the lock-up valve 85 and supplying control pressure to the lock-up valve 85, the valve 85 is moved to the left, whereby the hydraulic pressure in the lock-up release line 148 is discharged and the lock-up clutch 17 is engaged.

In addition to the above configuration, this hydraulic circuit 50 is equipped with a vacuum throttle valve 86 for controlling the pressure regulation value of the line pressure by the pressure regulation valve 52. This vacuum throttle valve 86 is operated by a vacuum diaphragm 87 to which boost pressure is introduced from the downstream side of a throttle valve (not shown) in the intake passage of the engine. It is designed to receive a large pressing force in the direction. Further, line pressure is introduced into the vacuum throttle valve 86 from the pressure regulating line 102 via a line 150, and a modulator pressure obtained by regulating this oil pressure is generated in a modulator pressure line 151. However, the pressure regulation value of this modulator pressure is increased as the pressing force from the vacuum diaphragm 87 to the right increases (as the boost pressure increases). This modulator pressure is introduced into the pressure booster boat 520 of the pressure regulating valve 52 through the line 152, so that the line pressure regulated by the pressure regulating valve 52 increases as the boost pressure increases. The pressure will be regulated. In addition, the vacuum throttle valve 86
A backup line 153 led from the aforementioned backup control valve 81 is connected to.

Then, the backup control valve 81 has a third
The control pressure generated in the control line 123
1 and when the valve 81 moves to the left, the line 154 branched from the fourth line pressure line 114h passes through the backup valve 88 and the backup control valve 81 to the backup line 1.
53. As a result, in the lunge and 2 ranges where hydraulic pressure is generated in the fourth line pressure line 114 and the third control line 123, the vacuum throttle valve 8
A backup pressure is introduced at 6 to increase the modulator pressure or line pressure. Here, in order to generate oil pressure in the 3rd II 111ml line 123 in the 1.2 range, the 3rd shift solenoid pulp 73 is turned ON in these ranges as described above (see Table 2). .

Moreover, the above modulator pressure is the modulator pressure line 15.
The pressure reduction boat 52d of the pressure regulating valve 52 is connected to the pressure reduction boat 52d of the pressure regulating valve 52 via the cutback valve 89 by the pressure reduction line 155 branched from 1.
It is set to be introduced in In that case, the cutback valve 89 operates to connect the pressure reduction line 155 with the control pressure introduced from the line 156 in the second or higher gears where control pressure is generated in the first control line 121. Therefore, the pressure regulation value of the line pressure by the pressure regulation valve 52 is cut back (pressure reduced) at the second gear or higher.

However, in this hydraulic circuit 50, as shown in an enlarged view in FIG.
2' vacuum boat 52 (a bellows 91 filled with gas at a constant pressure is placed at the end on the l side facing each other via a spring 92. When the pressure is approximately equal to this, the spool 52' is in a contracted state and does not exert any separate action on the spool 52', but when the surrounding air pressure drops below atmospheric pressure, the internal pressure becomes relatively high. , and presses the spool 52' to the left in the drawing via the spring 92. Therefore, in the pressure regulating valve 52, the spool 52'
' is pushed against the pressure regulating spring 52'' in the direction of communicating the pressure regulating boat 52a with the drain boat 52e, thereby reducing the line pressure regulated by the pressure regulating valve 52. Here, as described above, the modulator pressure is introduced into the pressure increasing boat 52c of the pressure regulating valve 52, but the modulator pressure introduced into this boat 52c moves the auxiliary spool 52'' to the right in the drawing. By doing so, the spool 52' is connected to the drain boat 52.
e is pushed in the closing direction, thereby increasing the line pressure in accordance with the modulator pressure.

In addition, each solenoid valve 7 in the above hydraulic circuit 50
1 to 75 are turned ON and OFF by the electric charge m+ signal from a control circuit (not shown), but this control circuit is controlled by the vehicle speed of the vehicle concerned (or the rotational speed of the torque converter output shaft 16 corresponding to the vehicle speed). Signals indicating the opening degree of the throttle valve in the intake passage of the engine, etc. are input, and the control signal is outputted in accordance with the operating state of the vehicle and engine indicated by these signals.

Next, the operation of this embodiment will be explained.

The first to third shift solenoid valves 71 to 73 in the hydraulic circuit are turned ON by a signal from a control circuit (not shown).
When the OFF operation is performed, 1-2.2-3.3
-4 shift valves 61 to 63 operate and each clutch 27
．． Hydraulic fluid is selectively supplied to the actuators of 28.44 and brake 31.36.45, in this way depending on the operating conditions of the vehicle and engine in question.
Shift control is performed according to the table. In addition, by turning ON and 0FFlj1 of the lock-up valve 75,
Lock-up clutch 17 according to a preset area
The engagement and release control is performed.

The line pressure supplied to each actuator is set by the pressure regulating valve 52 in the hydraulic circuit 50, and as shown in FIG.
A modulator pressure generated by a vacuum throttle valve 86 according to the boost pressure of the engine is introduced into the pressure booster boat 52C, and the spool 52' is pushed in the direction of closing the drain boat 52e. Therefore, the line pressure to which the pressure regulating valve 52 is set increases as the boost pressure increases, as shown by the solid line in FIG. 4. As a result, when the boost pressure, that is, the engine output is large, the line pressure supplied to each actuator is also increased, so that the friction member such as the clutch or brake can reliably transmit the torque corresponding to the engine output. In addition, when the boost pressure, that is, the engine output is low, the line pressure supplied to the actuator is also lowered to prevent or reduce shift shock caused by the line pressure being too high when the friction member is engaged. Become.

However, when the vehicle is traveling at high altitudes with low atmospheric pressure, the engine output for a given boost pressure is lower than when driving at low altitudes, so conventionally, the pressure regulating valve was set to correspond to the boost pressure. The line pressure generated becomes excessive relative to the engine output.

However, as shown in FIG. 3, in the pressure regulating valve 52 according to this embodiment, a bellows 91 is disposed on the end surface of the spool 52' on the pressure reducing boat 52d side via a spring 92.
When the atmospheric pressure is low, this bellows 91 expands and moves the spool 52' to the drain boat 5 via the spring 92.
2e is pressed in the direction of opening, the line pressure for a constant boost pressure is set to a lower pressure than when driving on low ground, as shown in Figure 5, and the characteristics of the line pressure for the boost pressure are also shown in Figure 4. It is generally lower as shown by the broken line. This allows the line pressure supplied to the hydraulic actuator to be matched to the torque or engine output to be transmitted by the clutch or brake when the automatic transmission shifts, even when driving at high altitudes where the engine output is reduced. This prevents a large shift shock from occurring due to excessive line pressure.

In this embodiment, the pressure regulating valve 52 is equipped with a bellows 91, so that the valve 52 is equipped with a bellows 91 when traveling at high altitudes with low atmospheric pressure.
Although the spool 52' is configured to be pressed in the pressure reducing direction,
The vacuum throttle valve 86 that supplies modulator pressure for pressure increase to the pressure regulating valve 52 may be provided with a bellows to lower the modulator pressure when traveling at high altitudes.

That is, as shown in FIG. 6, if a bellows 91' filled with gas at a constant pressure is placed opposite to the end surface of the spool 86' of the vacuum throttle valve 86 on the side opposite to the vacuum diaphragm 87 via a spring 92'. , when the bellows 91' expands due to the low atmospheric pressure, the spool 86' is pushed in the direction of closing the input port 86a connected to the input line 102, resulting in a constant boost pressure, i.e., the vacuum diaphragm 87. For a constant pressing force in the direction of opening the input port 86a, the modulator pressure generated in the modulator pressure line 151 will decrease.

Therefore, in the pressure regulating valve 52 through which this modulator pressure is introduced into the pressure increasing boat 52c, when the atmospheric pressure is low,
The line pressure that is set according to the modulator pressure is set to a low pressure.

Further, in the embodiment shown in FIG. 7, the modulator pressure generated by the vacuum throttle valve 86 is lowered when driving at high altitudes where atmospheric pressure is low, similar to the embodiment shown in FIG. , an input boat 86a to which the input line 102 is connected to the cylinder 86'' into which the spool 86' is fitted, an output boat 86b to which the modulator pressure line 151 is connected, and the like are provided.
A pressure regulating action is performed between the cylinder 86'' and the spool 86'.A bellows 91'' is disposed opposite to the end of the cylinder 86'' on the vacuum diaphragm 87 side, and A spring 92'' is located at the end. Therefore, according to this embodiment, the bellows 9
1'' when not inflated, the pressing force of the vacuum diaphragm 87 presses the Lisbourg 86' in the direction of opening the input port 86a, and when the bellows 91'' expands,
The cylinder 86'' is moved relative to the spool 86' in the direction of closing the input port 86a, and the modulator pressure with respect to the constant boost pressure is reduced as in the above embodiment.

Furthermore, in the embodiment shown in FIG. 8, for the same purpose, an orifice 155' is provided on the cutback line 155 led to the pressure reducing boat 52d of the pressure regulating valve 52, and a drain is provided from the downstream side of the orifice 155'. Line 155”
A duty solenoid valve 93 is installed on the line 155''.Then, the opening/closing time ratio of the duty solenoid valve 93 is controlled by a signal from a sensor that detects atmospheric pressure. , the cutback pressure introduced into the pressure reducing boat 52d of the pressure regulating valve 52 is increased when the atmospheric pressure is low, and the spool 5
2' is configured to press in the pressure reducing direction. Therefore, also in this embodiment, the line pressure set by the pressure regulating valve 52 is set lower when the vehicle is traveling at high altitudes where the atmospheric pressure is low than when traveling at low altitudes.

(Effects of the Invention) As described above, according to the present invention, the line pressure supplied to the actuator of each friction member is set according to the opening degree of the throttle valve in the intake passage of the engine or the boost pressure downstream of the valve. In this automatic transmission, the line pressure is corrected to be lower when the atmospheric pressure is low, so even when driving at high altitudes where engine output is reduced due to low atmospheric pressure, the line pressure can be reduced. It will be adapted to the engine power or the torque transmitted by the friction member. This prevents occurrence of large shift shocks due to line pressure becoming excessive relative to engine output or transmission torque when traveling at high altitudes.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. 2 to 5 show a first embodiment of the present invention, FIG. 2 is a diagram showing the structure of an automatic transmission and a hydraulic circuit, and FIG. 3 is an enlarged view of the area around the pressure regulating valve in the hydraulic circuit. 4 is a characteristic diagram of the line pressure with respect to the boost pressure obtained in this embodiment, and FIG. 5 is a characteristic diagram of the line pressure with respect to the traveling altitude. Also, the 6th
．． Figure 7 shows the second embodiment of the present invention. FIG. 8 is an enlarged view of the area around the vacuum throttle valve showing the third embodiment, and FIG. 8 is an enlarged view of the area around the pressure regulating valve showing the fourth embodiment. 10... Torque converter, 20.40... Speed change gear mechanism, 27.28, 31, 36.44° 45... Friction member, 27a, 28a, 31a. 36a, 44a, 45a... actuator, 5
0...Hydraulic circuit, 52...Line pressure setting means (pressure regulating valve), 91.91', 91", 93...Line pressure correction means (91, 91', 91"...Bellows,
93...Duty solenoid valve).

Claims (1)

[Claims] (1) A torque converter connected to the output shaft of the engine, a speed change gear mechanism connected to the output shaft of the torque converter, a plurality of friction members that switch the power transmission path of the speed change gear mechanism, and these friction members. The hydraulic actuator has a plurality of hydraulic actuators that respectively operate the actuators, and a hydraulic circuit that controls the supply and discharge of hydraulic pressure to and from these actuators, and the hydraulic circuit is provided with line pressure setting means that sets the line pressure to be supplied to the actuators. A hydraulic control device for an automatic transmission, comprising line pressure correction means that operates according to atmospheric pressure and lowers the line pressure set by the line pressure setting means when the atmospheric pressure is low. A hydraulic control device for an automatic transmission characterized by: