JPS62159838A - Line pressure control device for automatic variable transmission - Google Patents

Abstract

PURPOSE:To prevent a select shock from being generated at full closed reduction time, by getting a line pressure characteristic, which corresponds, to the utmost, with the required line pressure of a hydraulic actuator such as a band brake, at full closed reduction. CONSTITUTION:In the line pressure regulating/controlling circuit of a control unit 200, quantity of oil led into a back pressure chamber 102a of a pressure regulating valve 102, correspondingly with the turbine rotating speed TSP, is regulated, when the select position is in the low-speed stage range and a throttle is full closed, based on the turbine rotating speed TSP output from a turbine rotating speed sensor TS, the select position output from a select position sensor PS, and the throttle full-closing output from an accelerator switch ASW. By this matter, the line pressure PL of a pressure line 101 is regulated, and as this line pressure characteristic is set as it corresponds with the required line pressure PL0 to the utmost, the generation of a select shock is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a line pressure control device for an automatic transmission, and more particularly to one that increases line pressure during fully closed deceleration.

(Prior art) In general, automatic transmissions are
BACKGROUND ART A combination of a multi-stage gear transmission mechanism having a gear mechanism such as a star gear mechanism and a hydraulic mechanism for controlling the same is widely used.

In the control of this type of automatic transmission, the line pressure oil path of the hydraulic mechanism is switched, and the hydraulic actuators attached to the multi-stage transmission mechanism, such as band brakes and clutches, are actuated as appropriate. It is designed to obtain the following gears. And the hydraulic mechanism usually has
A select valve is incorporated, and the driver can selectively operate between a normal driving range and a low gear range.

In other words, the general driving range is called the D range, and in this range, a hydraulic circuit is formed that automatically shifts gears from 1st gear to the highest gear (for example, 4th gear), and the low gear range is called the L range or 2 range. As it is called, a hydraulic circuit is formed exclusively for low gears, that is, from 1st gear to 2nd gear, or to fix 2nd gear, and in which engine braking can be applied.

In such automatic transmissions, it is desirable to adjust the line pressure in accordance with the torque applied to hydraulic actuators such as band brakes and clutches.

In other words, the torque applied to the hydraulic actuator during driving changes depending on the torque of the engine output shaft, which changes depending on the load, and the amplification effect of the torque converter. Therefore, the line pressure PLO required by the hydraulic actuator depends on, for example, the vehicle speed and the throttle. When the opening degree is viewed as a parameter, it becomes as shown in FIG. In FIG. 4, fully open means that the accelerator opening is fully open, and fully closed means that the accelerator opening is fully closed.

For this reason, the above-mentioned automatic transmission is generally set so as to obtain line pressure PLo characteristics as shown in FIG. 5 during driving in order to meet the above-mentioned required line pressure PLO.

By the way, the torque TE applied to the hydraulic actuator during fully closed deceleration, that is, when using engine braking.
As shown in FIG. 5S6, this is different from that during the above-mentioned driving. In other words, during fully closed deceleration, the torque transmitted from the driving wheels to the transmission mechanism of the automatic transmission is in the opposite direction to that during driving, and the higher the rotation speed of the engine drive system, the larger the torque.

For this reason, as seen in Japanese Patent Laid-Open No. 55-44108, a line pressure control device has been proposed which increases the line pressure to a predetermined pressure during fully closed deceleration.

(Problems to be Solved by the Invention) However, in the conventional line pressure control device, the line pressure during fully closed deceleration is set to a certain constant pressure value.

For this reason, the set pressure PL had to be set based on the required line pressure PLO at high speeds, as shown in FIG. 7, when the rotational speed of the engine drive system is viewed in terms of vehicle speed. This is because if the required line pressure PLO at low speeds were set as a reference, the engagement force of the friction elements would be insufficient and the effectiveness of the engine brake would be weakened.

By the way, low speed ranges such as 2nd range are also used to obtain engine braking, but in the conventional line pressure control device, as mentioned above, it is necessary to set the line pressure based on the high speed range. When switching from the D range to a low gear range such as the 2 range in order to obtain engine braking in the range, there is a problem in that the engagement force of the friction element is too strong and a so-called select shock occurs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a line pressure control device for an automatic transmission that prevents as much as possible the occurrence of select shock during fully closed deceleration.

(Means and operations for solving the problem) The present invention focuses on the required line pressure PLo (broken line in Fig. 7) of a hydraulic actuator such as a band brake during full-throttle deceleration, and the It is designed to obtain line pressure characteristics that are similar to the above.

Specifically, it is built into the engine's drive system, and can be set between a general driving range, in which gears are shifted up to the highest speed, and a low gear range, in which engine braking is applied, through selective operation by the driver. Assuming an automatic transmission,
A rotation speed detection means for detecting the rotation speed of an engine drive system; a throttle full-open detection means for detecting a fully open throttle; a select position detection means for detecting that a low gear range is selected; and the rotation speed detection means. , the throttle fully closed detection means;
and receiving a signal from the select position detection means,
a line pressure control means that adjusts the line pressure according to the rotation speed of the engine drive system when the throttle is fully open and in the low gear range, and the line pressure control means adjusts the line pressure according to the rotation speed of the engine drive system when the engine drive system rotation speed is low. The configuration is such that the line pressure is lower than when the rotational speed is high.

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

In FIG. 2, which shows a cross section of a mechanical part and a hydraulic control circuit of an electronically controlled automatic transmission, the automatic transmission AT includes a torque converter 10, a multi-gear transmission mechanism 20, and a torque converter 10 and a multi-gear transmission mechanism 20. and an automatic drive planetary gear transmission mechanism 50 disposed between the two.

The torque converter IO includes a pump 11 that is coupled to the engine output shaft 1, a turbine 12 that is disposed opposite to the pump 11, and a stator 13 that is disposed between the pump 11 and the turbine 12. A converter output shaft 14 is coupled to the converter output shaft 14 . A lock-up clutch 15 is disposed between the converter output shaft 14 and the pump 11. This lock-up clutch 15
is constantly biased in the direction of engagement, that is, in the direction of locking up (directly connecting) the engine output shaft 1 and the torque converter output shaft 14, by hydraulic fluid pressure circulating through the torque converter output shaft, and is also biased by an externally supplied release valve. It is held open by hydraulic pressure.

The multi-stage gear transmission mechanism 20 has a front planetary gear mechanism 21 and a rear planetary gear mechanism 22, and a sun gear 23 of the front planetary gear mechanism 21 and a sun gear 24 of the rear planetary gear mechanism 22 are connected via a connecting shaft 25. There is. Multi-stage gear transmission mechanism 2
The 0 input shaft 26 is connected to the connecting shaft 25 via the front clutch 27 and to the internal gear 29 of the front planetary gear mechanism 21 via the rear clutch 28. Connecting shaft 25 or sun gear 23.2
A front brake 30 is provided between the transmission case 4 and the transmission case. The planetary carrier 31 of the front planetary gear mechanism 21 and the internal gear 33 of the rear planetary gear mechanism 22 are connected to an output shaft 34, and a rear brake 36 is connected between the planetary carrier 35 of the rear planetary gear mechanism 22 and the transmission case. A one-way clutch 37 is provided.

In the overdrive planetary gear transmission mechanism 50,
A planetary carrier 52 that rotatably supports a planetary gear 51 is connected to the output shaft 14 of the torque converter 10, and a sun gear 53 is connected to an internal gear 55 via a direct coupling clutch 54. An overdrive brake 56 is provided between the sun gear 53 and the transmission case, and the internal gear 55 is connected to the input shaft 26 of the multi-gear transmission mechanism 20.

The multi-gear transmission mechanism 20 is of a conventionally known type and has three forward speeds and one reverse speed, and can obtain the desired speed by appropriately operating the clutches 27, 28 and brakes 30, 36. It is something. The overdrive planetary gear transmission mechanism 50 connects @14.26 in a direct connection state when the direct coupling clutch 54 is engaged and the brake 56 is released, while the brake 56 is engaged and the clutch 54 is released. When @14.26 is combined with overdrive.

The automatic transmission AT described above includes a hydraulic control circuit CK as shown in FIG. This hydraulic control circuit CK
has an oil pump 100 driven by an engine output shaft 1, and the hydraulic oil discharged from this oil pump 100 into a pressure line 101 has a drain amount at a pressure regulating valve 102 (amount discharged from port x): By adjusting A, the pressure is adjusted and guided to the select valve 103. The select valve 103 has select positions of 1.2, D, N, R, and P, and when the select valve 103 is in the 1.2 and D positions, the pressure line 101 is connected to the port of the select valve 103. ) Connects to a, b, and c. Port a is rear clutch 2
8, and when the valve 103 is in the above-mentioned position, the rear clutch 28 is held in an engaged state. Port a is also connected near the left end of l-2 shift valve 110, pushing its spool to the right in the figure. Port a is Sarani 1st
1-2 shift via line Ll [to the right of 1-110, to the right of the 2-3 shift valve 120 via the second line L2, and to the right of the 3-4 shift valve 130 via the third line L3.
are connected to the right end of each.

Said first, second and third lines L1, second and third lines
from the first, second and third drain lines D, respectively.
L1. DL25 and DL3 are branched, and these drain lines DL1. DL2 and DL3 have first and second drain lines that open and close the drain lines DLI, DL2 and DL3.
, third solenoid valve SL1. S2 and S3 are connected. The above solenoid valves SLI, S2, and S3 are:
When demagnetized while line 101 and port a are in communication, each drain line DLI, DL2, DL3 is closed,
As a result, 1. The pressure in the second and third lines is increased.

Port b is also connected to the second lock valve 105 via line 140, and this pressure acts to push the spool of the second lock valve 105 downward in the figure. When the spool of the second lock valve 105 is in the downward position, the line 140 and the line 141 communicate with each other, and hydraulic pressure is introduced into the engagement side pressure chamber of the 7-actuator 108 of the front brake 30 to maintain the front brake 30 in the operating direction. do. FIG. 8 shows details of the front brake 30, and the operating loft 108a of the actuator 10g is in the direction of shaft rotation during driving, that is, in the direction of rotation of the brake drum (
In FIG. 8, the band brake 30 extends in the direction of the arrow.
A is wound tightly, thereby achieving self-servo performance during driving.

Port C is connected to second lock valve 105, and this pressure acts to push the spool of second lock valve 105 upward. Further, port C is connected to the 2
-3 is connected to the shift valve 120. this line 10
6, when the solenoid valve SL2 of the second drain line DL2 is demagnetized to increase the pressure in the second line L2, and this pressure moves the spool of the 2-3 shift valve 120 to the left, the line Please contact 107. line 1
07 is connected to the release side pressure chamber of the actuator 108 of the front brake 30, and when hydraulic pressure is introduced into the pressure chamber, the actuator 108 operates the brake 30 in the release direction against the pressure of the engagement side pressure chamber. let In addition, the pressure in the line 107 is
09, and this clutch 27 is engaged.

The select valve 103 is connected to the pressure line 101 in one position.
and has a port d leading to line 11
2 to reach the l-2 shift valve 110, and then line 1
13 to the actuator 114 of the rear brake 36. The 1-2 shift valve 110 and the 2-3 shift valve 120 operate solenoid valves SLI and SLI in response to predetermined signals.
When the second gear is demagnetized, the spool is moved to switch the line, thereby operating a predetermined brake or clutch, and performing a 1-2, 2-3 speed change operation, respectively. The hydraulic control circuit CK is also provided with a vacuum throttle valve 116 that changes the line pressure from the pressure regulating valve i02 according to the magnitude of the intake negative pressure, and a throttle backup valve 117 that assists the throttle valve 116. That is, the vacuum throttle valve 116 and the pressure regulating valve l.

It is connected to the back pressure chamber (port a) of No. 2 through a line 118.

Further, in the hydraulic control circuit CK of this example, a 3-4 shift valve 130 and an actuator 132 are sunk in order to control the clutch 54 and brake 56 of the M star gear transmission mechanism 50 for overdrive. The engagement side pressure chamber of the actuator 132 is connected to the pressure line 101, and the pressure of the line 101 pushes the brake 56 in the engagement direction. This 3-4 shift valve is also similar to the 1-2. 101 and line 122 are cut off, and line 122 is drained. As a result, the hydraulic pressure acting on the release side pressure chamber of the actuator 132 of the brake 56 disappears, and the brake 56
The actuator 134 of the clutch 54 acts to release the clutch 54 in the engaging direction.

Further, the hydraulic control circuit CK of this example is provided with a lock-up control valve 133.
33 is the boat a of the select valve 103 via the line L4.
is communicated with. A drain line DL4, which is provided with a solenoid valve SL4 like the drain lines DLI, DL2, and DL3, branches off from this line L4. The lock-up control valve 133 is configured such that when the drain/idle valve SL4 is energized to close the drain line DL4 and the pressure in the line L4 increases, its spool blocks the lines 123 and 124, and the line 124 is drained. The lock-up clutch 15 is moved in the operating direction.

In the above configuration, the operational relationship between each gear stage, lockup, and each solenoid, and the operational relationship between each gear stage, clutch, and brake are shown in Tables 1 to 3 below.

(The following is a blank space) The hydraulic control circuit CK that performs the basic control described above in Table 1 and Table 2 is also provided with line pressure control means 140 that adjusts the line pressure during fully closed deceleration in the 2nd or 1st range. Here, in order to adjust the line pressure using the pressure regulating valve 102, the line pressure control means 140 connects the boat a which opens into the back pressure chamber 102a of the pressure regulating valve 102 and the pressure line 101 to the line 14IDE. connected, line 141
A duty solenoid valve 142 is interposed therein. That is, as shown in FIG. 1, the line pressure of the pressure line 101 that flows from the hydraulic pump 100 to the manual valve 103 is introduced into the back pressure chamber 102a of the pressure regulating valve 102 through the line 141. The line pressure of the pressure line 101 is adjusted by adjusting the hydraulic pressure introduced into the back pressure chamber 102a from the line 141 using the dual inlenoid valve 142.

FIG. 3 shows an example of a control device for an automatic transmission AT according to the present invention, which controls the hydraulic control circuit CK associated with the above-mentioned automatic transmission aAT to perform speed change control and lock-up control. It is shown together with an engine EN incorporating an automatic transmission AT.

In FIG. 3, the control unit 200 includes a lock-up control circuit that performs lock-up control for the automatic transmission aAT, a shift control circuit that performs shift control, and a line pressure adjustment control circuit during full-throttle deceleration. ing. Further, the rotation speed of the output shaft 14 of the torque converter 10 of the automatic transmission AT, and therefore the turbine rotation speed TSP, is detected by the turbine rotation speed sensor TS attached thereto, and the throttle valve installed in the intake passage 203 of the engine EN is detected. The throttle opening degree TH of 204 is detected by the engine load sensor LS, and both sensors TS and LS
A signal from the control unit 200 is input to the control unit 200. Also,
As information necessary for the operation of the line pressure adjustment control circuit, the select position is detected by the select position sensor PS attached to the select lever that performs the range switching operation, and the accelerator switch As attached to the accelerator pedal.
W detects that the throttle is fully closed, and the respective signals are manually input to the control unit 200.

Note that, here, the turbine rotational speed TSP is treated as information corresponding to the rotational speed of the engine drive system, and the throttle opening degree TH is treated as information corresponding to the engine load.

The speed change control circuit of the control unit 200 receives a turbine rotational speed signal from the turbine rotational speed sensor TS, a throttle opening signal from the engine load sensor LS, and a driving mode sensor (not shown) that detects the driving mode. For example, the turbine rotation speed (
(handled as corresponding to vehicle speed)--by comparing it with the shift-up shift line and shift-down shift line of the shift map predetermined based on the engine load characteristics,
Calculate whether or not to change gears. and.

Depending on the result of this calculation, a shift up signal or a shift down signal is sent to the 1st, 2nd, and 2nd positions of the hydraulic control circuit GK. The output is output to the third solenoid valves SLI, SL2, and SL3, and these are selectively energized in the manner shown in Table 1 to change the gear position of the automatic transmission AT to an upper gear position (upshift) or a lower gear position. It performs control to shift to the next stage (shift town) and outputs a shift-up signal or a shift-down signal to the lock-up control circuit.

In addition, in the lock-up control circuit of the control unit 200, the turbine rotation speed TSP from the turbine rotation speed sensor TS, the throttle opening signal and the driving mode signal from the engine load sensor LS are transmitted in the lock-up control circuit of the control unit 200, as in the case of the transmission control circuit described above. Hail information, for example, turbine rotation speed -
A calculation is made as to whether lock-up or lock-up should be released by comparing the lock-up operation line and lock-up release line of the shift map, which are predetermined based on engine load characteristics. Then, according to the result of this calculation, a lock-up activation signal or a lock-up release signal is output to the fourth valve SL4 of the hydraulic control circuit CK.

In addition, the line pressure adjustment control gg circuit of the control unit 200 performs selection based on the turbine speed TSP from the turbine speed sensor TS, the select position from the select position sensor PS, and the fully closed throttle from the accelerator switch ASW. The position is in the low gear range, for example 2
When both the conditions of range and fully closed throttle are satisfied, the turbine rotation speed TSP
A pulse signal with a pulse width corresponding to
Adjust the amount of oil introduced. This allows pressure line 10
The line pressure PL at this time is controlled by the duty solenoid valve 142 so that the characteristics shown in FIG. 9 are obtained. This line pressure characteristic is the above-mentioned required line pressure PL.
o (broken line in FIG. 7) as much as possible. Of course,
If both of the above conditions are not satisfied, the line 141 is shut off and normal line pressure adjustment is performed, that is, the line pressure is adjusted based on the oil pressure from the vacuum throttle valve 116 through the line 118 (see FIG. 5). It will be done.

From this, when range switching is performed from D range to 2 range to obtain engine braking, band brake is applied under line pressure PL adjusted to a value close to line pressure PLO required by the actuator that operates the friction element. As a result, the occurrence of so-called select shock is prevented.

Although one embodiment of the present invention has been described above, the rotation/number of the engine drive system is detected by the engine output shaft or the automatic transmission A.
Of course, the rotation speed of the T output shaft may be used. Further, the line pressure characteristics shown in FIG. 9 may be set so that the line pressure increases in steps as the rotational speed of the engine drive system increases.

(Effects of the Invention) As is clear from the above explanation, when switching to a low gear range to obtain engine braking, the line pressure is adjusted to the value required by the friction element 7 cutuator.
It is possible to prevent the occurrence of select shock.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of an embodiment of the present invention. FIG. 2 is a cross-sectional view of a mechanical part of an automatic transmission according to the embodiment and its hydraulic circuit. FIG. 3 is a diagram showing the hydraulic circuit of the automatic transmission according to the embodiment. Overall system diagram, Figure 4 is a diagram showing the required line pressure during driving, Figure 5 is a diagram showing the line pressure characteristics during driving in the embodiment, Figure 6 is applied to the 7 friction element 7 actuators during fully closed deceleration. An explanatory diagram of torque. Figure 7 is an explanatory diagram of conventional line pressure adjustment during fully open deceleration. Figure 8 is a sectional view showing the band brake and actuator. Figure 9 is line pressure during fully closed deceleration in the embodiment. It is a characteristic diagram. AT: Automatic transmission D range General driving range 1.2 Range: Low gear range ASW: Accelerator switch PS: Select position sensor TS: Turbine rotation speed sensor 140 Line pressure control means 142: Chuty solenoid valve Fig. 1 Higgle Figure 3 Figure 4 ■ Figure 5 ■ Figure 6 E f Figure 7 ■ Figure 9

Claims (1)

[Claims] (1) An automatic system that is built into the engine's drive system and can be set in a general driving range, in which gears are shifted up to the highest speed, and in a lower gear range, in which engine braking is applied, depending on the driver's selective operations. In the transmission, a rotation speed detection means for detecting the rotation speed of an engine drive system, a fully closed throttle detection means for detecting a fully closed throttle, a select position detection means for detecting that a low gear range is selected, Receiving signals from the rotation speed detection means, the throttle fully closed detection means, and the select position detection means, when the throttle is fully closed and in a low gear range, the line pressure is adjusted according to the rotation speed of the engine drive system. and line pressure control means, wherein the line pressure control means is configured to lower the line pressure when the rotational speed of the engine drive system is low compared to when the rotational speed is high. An automatic transmission line pressure control device featuring: