JPH08105540A - Line pressure control device for vehicular automatic transmission - Google Patents

Abstract

PURPOSE: To provide a line pressure control device for a vehicular automatic transmission, which can execute optimum speed change control by setting up line pressure at the time of deceleration with a slope concerned with down-hill running taken into consideration. CONSTITUTION: At present, a speed change range is fixed, a driver does not select the range (S31), when a speed change range is a D range (S32), and furthermore when it is at the time of down-hill running (S33), an optimum line pressure PL, is set up in advance in response to vehicle speeds VSP (S35), and moreover, a correction factor K is read in, which corrects the line pressure P2 , based on slope resistance (S36). Besides, while the range is being selected, maps for a range selection shall be used (S44 through S46).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a line pressure control device for an automatic transmission in a vehicle in which an output shaft of an engine is connected to the automatic transmission with a torque converter.

[0002]

2. Description of the Related Art Generally, an automatic transmission of a vehicle equipped with an internal combustion engine is adapted to be automatically shifted based on a shift pattern preset according to a running state of the vehicle. That is, the shift pattern for setting the shift speed according to the vehicle speed and the engine load (for example, throttle opening) is stored in the storage means of the control unit, and the shift is controlled according to this shift pattern. It should be noted that normally, the shift pattern is set so that the smaller the engine load is, the higher the shift speed is when the vehicle speed is the same.

However, in such a conventional automatic shift control device, for example, when a vehicle is descending a slope, the throttle opening is upshifted in response to a driver's deceleration request in which the throttle opening is fully closed. Since the deceleration effect due to is not sufficiently exerted, it leads to deterioration of vehicle drivability and eventually to overload of the foot brake.

Therefore, the applicant of the present invention has proposed a vehicle in which gear shift control is performed according to a gear shift pattern based on gradient resistance when the vehicle is decelerating (Japanese Patent Application No. 5-272698).
issue). On the other hand, in an automatic transmission, the discharge pressure of an oil pump is regulated to obtain a line pressure, which is supplied to a hydraulic circuit to be used as a hydraulic pressure of a torque converter and a hydraulic pressure of various speed change elements in a gear type transmission. However, this line pressure is generally set based on the load of the engine.

Further, in Japanese Patent Application No. 5-272698, when the driver selects from the D range to the 2nd speed range or the 1st speed range due to the intention of deceleration, the line pressure is set based on the vehicle speed during gear shifting, and It has been proposed to set a larger one of the line pressure and the limit pressure, which are set to increase in response to an increase in the throttle opening during non-shifting.

[0006]

However, in such a conventional line pressure control device for an automatic transmission for a vehicle, for example, when the vehicle is on a downhill, the vehicle is in the D range, and the driver releases the accelerator pedal. When the engine brake is operated, the throttle valve opening TVO is fully closed, so the line pressure is not set enough to activate the engine brake. Since the line pressure is not set enough to make the engine brake more effective, there is a fear that the effect of the engine brake will be deteriorated. Further, when the vehicle is going down a gentle slope, a limit pressure that is equal to or higher than the line pressure required to activate the engine brake may be set, which may lead to deterioration of fuel efficiency due to pump loss.

The present invention has been made in view of such a conventional situation, and the shift control can be optimized by setting the line pressure during deceleration in consideration of the slope related to the downhill. An object of the present invention is to provide a line pressure control device for an automatic transmission for a vehicle.

[0008]

Therefore, as shown in FIG. 1, the present invention provides a line pressure control device for an automatic transmission in a vehicle in which an automatic transmission with a torque converter is connected to an output shaft of an engine. Vehicle speed detection means A for detecting
Vehicle deceleration state detection means B for detecting the deceleration state of the vehicle,
The line pressure setting means C for setting the line pressure based on the detected vehicle speed, the gradient resistance detecting means D for detecting the gradient resistance of the vehicle road surface, and the vehicle deceleration state detecting means B have detected the deceleration state. Sometimes, the line pressure set by the line pressure setting means C is set to the gradient resistance detecting means D.
And a line pressure correction setting means E for correcting and setting based on the gradient resistance detected by.

The gradient resistance detecting means D can be constructed by a gradient sensor.

[0010]

According to the present invention having such a configuration, when the vehicle is decelerated, the line pressure setting means does not drive, for example, the line pressure actuator based on the line pressure set by the line pressure setting means. The line pressure is corrected based on the gradient resistance detected by the gradient resistance detecting means to correct and set the line pressure, and for example, the line pressure actuator is driven by the line pressure considering the gradient.

As a result, it is possible to prevent the line pressure from becoming insufficient and the engine braking not being effective during deceleration as in the conventional case. Therefore, the vehicle driving characteristics during deceleration can be optimized. . If the gradient resistance detecting means is composed of a gradient sensor, the gradient resistance on the road surface of the vehicle can be detected more easily.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 2, the engine 1 is connected to the automatic transmission 2 so that the generated torque is transmitted to vehicle drive wheels (not shown). The automatic transmission 2 includes a torque converter 3 for inputting the torque generated by the engine 1 through a fluid.
And a multi-stage speed change gear mechanism 4 for inputting the output of the torque converter 3 and changing and outputting the same, and a hydraulic mechanism 5 for driving these.

A plurality of solenoid valves (not shown) are incorporated in the hydraulic mechanism 5 of the speed change gear mechanism 4, and the speed change gear mechanism 4 is internally installed by switching the combination of opening and closing of the plurality of solenoid valves. A combination of engagement and disengagement of each clutch is switched so that the gear can be shifted to a desired gear. Here, regarding the general operation of the transmission gear mechanism 4 of the automatic transmission 2,
This will be described with reference to FIGS. 14 to 17.

A. D (drive) range or 1st speed of 2nd speed range (see Fig. 14) When the throttle opening is large such as during acceleration, the forward clutch 12 and the forward one-way clutch
13 and the low one-way clutch 14 are actuated to prevent the rear internal gear 17 from reversing. During steady state / coasting, the rear internal gear 17 rotates forward, so the forward one-way clutch 13 becomes free and idle, and the driving force is not transmitted between the output shaft 11 and the input shaft 10. ,
The engine brake does not work.

During deceleration, overrun clutch
The forward one-way clutch 13 is regulated from idling by engaging 15 (ON), but the low one-way clutch 14 becomes idling and idling, so the driving force between the output shaft 11 and the input shaft 10 is increased. Is not transmitted, the engine braking does not work.

B. In the D range or 2nd speed range (see Fig. 15) During acceleration, the forward clutch 12 is engaged, and the front planet carrier 16 and the rear internal gear are engaged via the forward one-way clutch 13.・ Gear 17
And are connected. The driving force is transmitted from the input shaft 10 to the rear sun gear 18, and the rear planetary gear is
The carrier 19 and the front internal gear 20 are normally rotated at the same speed.

Further, since the band brake 21 acts and the front sun gear 22 is fixed,
The rear internal gear 17 is normally rotated via the planet carrier 16 and the forward clutch 12 and the forward one-way clutch 13 connected to the planet carrier 16. Therefore, the speed is increased by the amount by which the rear internal gear 17 rotates as compared with the case of the first speed.

During steady state / coasting, the forward internal one-way clutch 13 is free and idling because the rear internal gear 17 is normally rotating, and the output shaft 11 and the input shaft 10 are not rotated. Since the driving force is not transmitted, engine braking does not work. When the overrun clutch 15 is engaged during deceleration, the forward one-way clutch 13 is prevented from idling, and the output shaft 11 and the input shaft are
Since the driving force will be transmitted between 10 and, the engine braking will be effective.

C. 3rd speed in the D range (see Fig. 16) During acceleration, the high clutch 23 is engaged and the input shaft 10 and the front planet carrier 16 are connected. Further, the forward clutch 12 and the forward one-way clutch 13 operate to connect the front planet carrier 16 and the rear internal gear 17.

The driving force is transmitted from the input shaft 10 to the rear sun gear 18 and the rear internal gear 17, and the rear sun gear 18 and the rear internal gear 17 are transmitted.
Gear 17 rotates at the same speed. Therefore, the rear planet carrier 19 also rotates forward together with the rear sun gear 18 and the rear internal gear 17. During steady state / coasting, the rear internal gear 17 rotates forward, so the forward one-way clutch 13 becomes free and idle, and the reverse driving force from the output shaft 11 is not transmitted to the input shaft 10 side. ,
The engine brake does not work.

When the overrun clutch 15 is engaged during deceleration, the forward one-way clutch
Since the reverse rotation of 13 is regulated and the driving force is transmitted between the output shaft 11 and the input shaft 10, the engine braking becomes effective. d. In the 4th speed of the D range (see Fig. 17) During acceleration, the high clutch 23 is engaged and the input shaft 10 and the front planet carrier 16 are connected. In addition, the brake band 24 acts and the front
Secure Sun Gear 22. The forward clutch
Although 12 is also engaged, it does not contribute to the driving force transmission because it is idling with the forward one-way clutch 13.

The driving force from the input shaft 10 to the front planet
It is transmitted to the carrier 16. When the front planet carrier 16 rotates in the forward direction, the front sun gear 22 is fixed by the brake band 24, so that the front internal gear 20 is accelerated, and the output shaft 11 connected to the front planetary gear 22 rotates in the normal direction. It will be transmitted in.

Since the one-way clutches 13 and 14 are not used to transmit the driving force during coasting and deceleration, the driving force is transmitted between the output shaft 11 and the input shaft 10, so that the engine braking is effective. It has become. The ON / OFF control of the plurality of solenoid valves for changing the speed of the speed change gear mechanism 4 is as follows.
This is performed based on a control signal (shift control signal) from a control unit 50 equipped with a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface and the like.

The overrun clutch 15 is engaged (ON) by opening (ON) the overrun solenoid valve 5 incorporated in the hydraulic mechanism 5 based on a signal from the control unit 50. As a result, the engine brake can be applied during deceleration as described above. Here, in order to obtain the line pressure P _L which is the working hydraulic pressure for the torque converter 3, the speed change gear mechanism 4 and the hydraulic mechanism 5, the oil pump 80 driven by the input shaft of the speed change gear mechanism 4 is used and the orifice 81 An electromagnetic valve 82, a pressure modifier valve 83 and a pressure regulator valve 84 are provided.

The electromagnetic valve 82 is also controlled based on a signal from the control unit 50 as described later, and obtains a pilot pressure based on the discharge pressure of the oil pump 80 guided through the orifice 81. The pressure modifier valve 83 amplifies the pilot pressure. The pressure regulator valve 84 regulates the discharge pressure from the oil pump 80 to a line pressure P _L proportional to the pilot pressure from the pressure modifier valve 83, and sends it to a hydraulic circuit such as the torque converter 3 and the hydraulic mechanism 5.

The shift control, overrun clutch engagement control, and line pressure control performed by the control unit 50 will be described below. Signals from various sensors are input to the control unit 50. The various sensors include a throttle sensor 6 that outputs an output signal according to the throttle opening TVO, a vehicle speed sensor 7 that detects a vehicle speed VSP by detecting the rotation speed of the output shaft of the automatic transmission 2, and a shift selector. A range switch 8a for detecting the range position of 4a, an inhibitor switch 8b as a gear position detecting means for detecting the gear position of the transmission gear mechanism 4, and a brake switch 9 for issuing a foot brake ON signal.
Is provided.

As a sensor according to the present invention, a gradient sensor 70 for detecting the gradient resistance of the vehicle on the road surface of the vehicle is provided. The control unit 50 has functions as line pressure setting means and line pressure correction setting means.
The control unit 50 also controls gear shifts based on signals from various sensors.

The shift control according to this embodiment will be described in detail with reference to the flowchart shown in FIG. In step 1 (denoted as S1 in the figure. The same applies hereinafter),
Read the input signals from various sensors. In step 2, it is determined whether the ON signal from the brake switch 9 is input. If YES, the process proceeds to step 5, where the previous vehicle speed VSP is set as the current vehicle speed VSP, and the previous vehicle acceleration α is set as the current vehicle acceleration α, and the process proceeds to step 7. If NO, go to step 3.

In step 3, it is judged whether or not the brake switch 9 was ON at the time of executing the flow last time. YE
If S, the process proceeds to step 4, where the current vehicle speed VSP is the current vehicle speed VSP, the previous vehicle acceleration α is the current vehicle acceleration α, and the process proceeds to step 7. If NO, go to step 6. In Step 6, the current and previous vehicle speed V
The acceleration α of the vehicle is calculated based on SP.

In step 7, the throttle opening TVO
Is below a predetermined value. If it is less than the predetermined value, it is determined that the vehicle is in a decelerating state, and the process proceeds to step 8. On the other hand, if it is larger than the predetermined value, the process proceeds to step 9. The step 7 constitutes a vehicle deceleration state detecting means. In step 9, it is determined whether or not the state where the throttle opening TVO is larger than the predetermined value has continued for a predetermined time. If YES, it is determined that the vehicle is not in the decelerating state, and the routine proceeds to step 14 in order to perform the normal shift control. On the other hand, if NO, it is determined that the vehicle is in a decelerating state, and the process proceeds to step 8. The step 9 is for preventing the drivability of the vehicle from being deteriorated due to the speed change control during deceleration of the vehicle and the speed change control during normal traveling being immediately switched due to the driver's unnecessary accelerator tilt or the like. It is a thing. Needless to say, the vehicle deceleration state detecting means can be configured to include the step 9.

In step 8, it is determined whether or not the current range is the D range based on the signal from the range switch 8a. If YES, proceed to step 10, NO
If so, the routine proceeds to step 14 in order to carry out normal shift control. In step 10, it is judged based on the signal from the inhibitor switch 8b whether or not the current gear position is the second speed or higher. If YES, go to step 11,
If NO, step to execute normal shift control.
Proceed to 14.

In step 11, it is judged whether the vehicle speed VSP is a predetermined value or more based on the signal from the vehicle speed sensor 7. If YES, then the process proceeds to step 12 in order to carry out shift control during deceleration. If NO, the routine proceeds to step 14 in order to carry out normal shift control so as not to cause engine stall or jerky feeling in the longitudinal direction of the vehicle. The predetermined value is a value set for each shift speed so that the rotation speed of the engine 1 obtained from the relationship between the shift speed and the vehicle speed is maintained at a rotation speed at which engine stall or the like does not occur. Is desirable.

In step 12, based on the current vehicle speed VSP and the current vehicle acceleration α, a deceleration shift pattern map (eg, FIG. 4, which is previously set and stored in the ROM).
From 5 and 6), the gear position and ON / OFF of the overrun clutch 15 are selected according to the deceleration state. Here, the shift pattern map during deceleration will be described with reference to FIGS.

FIG. 4 shows the case where the current gear stage is the 2nd speed.
For example, assuming that the downward gradient is large (the vehicle acceleration α is large in the vehicle acceleration direction), the gear position is maintained at the second speed, and the above-described overrun clutch 15 is operated to strongly apply the engine brake. Acceleration α of 0
Try to get close to.

When the vehicle is in the area, the vehicle acceleration α is smaller than that in the area, so that the current state is maintained. Specifically, when the throttle opening TVO is immediately after the transition from the large state to the deceleration state (immediately after the transition from the steady / acceleration state to the deceleration state), the second speed and the overrun clutch 15 / OFF state are set. maintain. Further, when the previous flow is executed, if the state other than the above is set to the second speed and the overrun clutch 15 is ON, the state is maintained and the vehicle operation accompanying the careless ON / OFF of the overrun clutch 15 is performed. The acceleration α of the vehicle is made to approach 0 while preventing the deterioration of the vehicle performance (hunting or the like).

When the vehicle acceleration α is in the region, when the vehicle acceleration α is in the vehicle deceleration direction, for example, when the downward gradient is smaller, the vehicle acceleration α increases in the deceleration direction and the braking feeling becomes large when the second speed is maintained. Therefore, to prevent this, upshift to 3rd gear and overrun clutch.
Turn on 15 to weaken the effect of engine braking so that the vehicle acceleration α approaches zero.

When the vehicle is in the area, when the vehicle acceleration α is large in the vehicle deceleration direction, for example, when the downhill is smaller than the area or the uphill, the vehicle is in such a case. Compared with this, the vehicle acceleration α further increases in the deceleration direction and the feeling of braking becomes greater. Therefore, in order to prevent this, the vehicle is upshifted to the fourth speed. As described above, in the case of the 4th speed, the one-way clutches 13 and 14 are not used, so that the engine braking is effective although it is weak.

In this way, the shift control is performed so that the acceleration α of the vehicle approaches 0, thereby preventing deterioration of the drivability of the vehicle during deceleration. Next, a case where the current gear is the third speed will be described with reference to FIG. If the current gear is in the third speed and the vehicle acceleration α is in a large region in the acceleration direction, the gear is downshifted to the second speed, and the overrun clutch 15 is turned on, assuming that the downward gradient is large, for example. Turn it on so that the engine brake is applied strongly.

When the vehicle is in the area, the vehicle acceleration α is not so large, so that the current gear is maintained,
Turn on the overrun clutch 15 to activate the engine brake. When in the area, the vehicle acceleration α
Is in the deceleration direction and the brake feeling becomes strong. Therefore, in order to prevent this, upshift to the fourth speed where engine braking is relatively ineffective and suppresses an increase in acceleration α in the deceleration direction.

In this way, the shift control is performed so that the acceleration α of the vehicle approaches 0, thereby preventing deterioration of the drivability of the vehicle during deceleration. Next, a case where the current shift speed is the fourth speed will be described with reference to FIG. If the current gear is in the fourth speed and the vehicle acceleration α is in a large region in the acceleration direction, for example, assuming that the downward gradient is large, the gear is downshifted to the second speed and the overrun clutch 15 is turned on. Turn it on so that the engine brake is applied strongly.

When the vehicle is in the region, the vehicle acceleration α is not so large as compared with the region. Therefore, the shift speed is downshifted to the third speed and the overrun clutch 15 is turned to O.
N, the effect of engine braking is weakened compared to the range. When the vehicle is in the region (10), the vehicle acceleration α is small or in the deceleration direction. Therefore, the fourth speed is maintained to maintain the current state, and the increase in the acceleration α in the deceleration direction is suppressed.

In this way, the shift control is performed so that the acceleration α of the vehicle approaches 0, thereby preventing deterioration of the drivability of the vehicle during deceleration. In step 13, the plurality of solenoid valves and the overrun solenoid valve 5 are drive-controlled based on the search result in step 12 to perform shift control during deceleration.

On the other hand, in step 14, the shift stage is searched according to the normal shift pattern (see FIG. 7). Step
In step 15, drive control of the plurality of solenoid valves and the like is performed according to the search result in step 14 to perform shift control during normal traveling. As described above, according to the present embodiment, when the vehicle is decelerated, the shift control is performed so that the vehicle acceleration α approaches 0 based on the actual acceleration α of the vehicle, so that the vehicle can be favorably decelerated. The operation characteristics are optimized.

The selection of ON / OFF of the overrun clutch 15 performed in step 12 will be described again with reference to the flowchart shown in FIG. In step 21, it is determined whether or not the current range is the D range based on the signal from the range switch 8a.
If YES, the process proceeds to step 22, and if NO, the process proceeds to step 23.

In step 22, it is judged whether or not it is a downhill time when there is a downgrade due to the output from the gradient sensor 70 or the vehicle acceleration α is large in the vehicle acceleration direction. Then, if YES, the process proceeds to step 24, and it is determined whether or not the current gear position is the fourth speed. here,
When the current gear position is in the fourth speed, that is, in the region of FIG. 4 described above (YES), when the vehicle acceleration α is large in the vehicle deceleration direction, for example, the downgrade is smaller than the region or the upgrade is higher. In such a case, the vehicle acceleration α further increases in the deceleration direction compared to the region, and the feeling of braking becomes larger. Therefore, in order to prevent this, the vehicle is upshifted to the 4th speed. In the case of the 4th speed, the one-way clutches 13 and 14 are not used, so the overrun clutch 15 is controlled to OFF. (Step 25).

On the other hand, if it is determined in step 24 that the current gear position is not the fourth speed, the process proceeds to step 26, and the region other than the region, that is, the region or the region exists, and in any region, the aforementioned Operate the overrun clutch 15 so that the engine brake is activated. In step 23, it is determined whether the current range is the second speed range or the first speed range based on the signal from the range switch 8a. If YES, the driver has fixed the speed to the second speed range or the first speed range in order to prevent the wheels from slipping. In this case, the above-mentioned overrun clutch 15 is operated to apply the engine brake. To do so, go to step 26.

On the other hand, if NO in step 23, it is determined that the driver is currently selecting the range, and the process proceeds to step 25 to control the overrun clutch 15 to OFF. In the present embodiment, as described above, even during deceleration, ON / OFF of the overrun clutch 15 is controlled based on the shift position, and it is possible to improve the vehicle drivability during deceleration operation. However, in order to perform the control, line pressure control as described below is required. That is, even if the control unit 50 performs the ON control of the overrun clutch 15, if the predetermined hydraulic pressure is not supplied to the hydraulic mechanism 5, the O of the overrun clutch 15 becomes O.
N / OFF control cannot be performed.

Next, the line pressure control performed by the control unit 50 will be described with reference to the flowchart shown in FIG. In step 31, it is determined based on the signal from the range switch 8a whether or not it is the time of selection in which the driver is currently selecting the range. Then, if it is determined that it is not the time of selection, the process proceeds to step 32 and below, and if it is determined that it is the time of selection, the process proceeds to step 42 and thereafter.

In step 32, it is judged whether or not the current range is the D range based on the signal from the range switch 8a. If YES, go to step 33, NO
If so, proceed to step 34. In step 33, it is determined whether or not it is a downhill time when there is a downgrade due to the output from the gradient sensor 70 or the vehicle acceleration α being large in the vehicle acceleration direction. Then, if YES, the process proceeds to step 35, and if NO, the process proceeds to step 34.

That is, when the routine proceeds to step 35, the gear change range is currently fixed, the driver has not selected the range, the gear change range is the D range, and further downhill. In this case, ON / OFF control of the overrun clutch 15 is performed depending on the gear position. However, if the line pressure control based on the normal throttle valve opening is performed, the driver closes the throttle opening due to the fact that the vehicle is downhill at this time, and thus the line pressure control cannot be performed reliably.

Therefore, in step 35, the downhill time map in which the optimum line pressure P _L is determined in advance corresponding to the vehicle speed VSP as shown in FIG. 10 is referred to, and based on the downhill time map, Set the hydraulic oil line pressure P _L. Where Figure 10
As shown in, the higher the vehicle speed VSP, the more the engine braking needs to be applied, so that slippage does not occur between the output shaft and the input shaft.
Set the line pressure P _L high.

Further, as the descending slope on the descending slope becomes steeper, it is necessary to apply more engine braking, and in order to consider the influence of the slope, the routine proceeds to step 36, where the slope resistance detected by the slope sensor 70 is detected. The correction coefficient K for correcting the line pressure P _L is read based on On the other hand, if it is determined in step 32 that the current range is not the D range, or if the shift range is the D range but it is not downhill, the driver intentionally operates the accelerator pedal. Since it is up to the driver to actuate the engine brake, the line pressure P _L should also be set based on the throttle opening TVO corresponding to the load on the engine. Therefore, in step 34, The line pressure is set based on the throttle opening TVO.

That is, in step 34, as shown in FIG. 12, the normal time map in which the optimum line pressure P _L is set in advance corresponding to the throttle opening TVO is referred to, and based on the normal time map, Set the hydraulic oil line pressure P _L. Here, FIG. 12 (a) current range indicates the line pressure P _L in the D range, FIG. 12 (b) current range indicates the line pressure P _L in the second speed range or 1 speed range There is.

If it is determined in step 31 that the selection is in progress and the process proceeds to step 42 and thereafter, first in step 42, as in step 32, the current range is determined based on the signal from the range switch 8a. Is in the D range. If YES, step 43
If NO, go to step 44. In step 43, it is determined whether or not it is a downhill time when there is a downgrade due to the output from the gradient sensor 70 or the vehicle acceleration α being large in the vehicle acceleration direction. Then, if YES, the process proceeds to step 45, and if NO, the process proceeds to step 44.

In other words, when the routine proceeds to step 45, the driver selects the range so that the shift range is shifting to the D range and the vehicle is further downhill. In this case, the overrun clutch is changed depending on the gear position. ON / OFF of 15
Control is implemented. However, if the line pressure control based on the normal throttle valve opening is performed, the driver closes the throttle opening due to the fact that the vehicle is downhill at this time, and thus the line pressure control cannot be performed reliably.

Therefore, at step 45, referring to the downhill shift time map in which the optimum line pressure P _L is set in advance in correspondence with the vehicle speed VSP as shown in FIG. 10, and based on the downhill shift time map. To set the line pressure P _L of the hydraulic oil. Further, as the gradient at the time of descending is steeper, it is necessary to apply more engine braking, and in order to consider the influence of the gradient, the routine proceeds to step 46, and the gradient resistance detected by the gradient sensor 70 is used for the above-mentioned determination. A correction coefficient K for correcting the line pressure P _L is read. Here, the correction coefficient K is shown in FIG.
As shown in, the smaller the gradient resistance of the vehicle on the road surface on which the vehicle travels, the larger the line pressure P _L is set.

On the other hand, if it is determined in step 42 that the current range is not the D range, or if the shift range is the D range but is not downhill, step 44 is shown in FIG. Thus, the line pressure is set based on the vehicle speed VSP. That is, D
When shifting from the range to the second speed range or the first speed range, the load resistance of the engine becomes a negative torque and is input to the transmission 4 via the torque converter 3. In that case, The transmission input torque is determined by the rotation speed of the input shaft, that is, the vehicle speed VSP. Therefore, the map in which the optimum line pressure P _L is determined in advance corresponding to the vehicle speed VSP is referred to, and the line pressure P _L of the hydraulic oil is set based on the map.

As described above, in the present embodiment, the vehicle speed VS is set when the shift range is the D range and when the vehicle is descending a slope.
Referring to downhill at a map that defines a pre-optimum line pressure P _L corresponding to P, and sets the line pressure P _L of the hydraulic fluid based on the map for at該降slope, during further downhill higher slope tight in, read as it is necessary to twist more engine braking, as the gradient resistance of the vehicle in the vehicle traveling road surface is small, the correction coefficient K is set to high set more line pressure P _L increases Then, the line pressure P _L is corrected.

Then, for example, a line pressure actuator is driven by the line pressure. As a result, it is possible to prevent the line pressure from being insufficient during deceleration and the engine braking not being effective as in the conventional case, so that the vehicle driving characteristics during deceleration can be optimized.

[0060]

As described above, according to the present invention,
When the vehicle is in the D range when descending a hill and the driver releases the accelerator pedal to operate the engine brake, the line pressure sufficient to activate the engine brake is set according to the vehicle speed. Since the line pressure is corrected based on the slope of the slope, it is possible to efficiently apply the engine brake. Further, even on a gentle downhill, it is possible to prevent the fuel pressure from being deteriorated due to the pump loss by setting the line pressure required to apply the engine brake appropriately.

That is, there is an effect that the line pressure during deceleration is appropriately set in consideration of the slope related to the downhill and the shift control is optimized.

[Brief description of drawings]

FIG. 1 is a block diagram according to the present invention.

FIG. 2 is an overall configuration diagram of an embodiment according to the present invention.

FIG. 3 is a flowchart illustrating shift control in the above embodiment.

FIG. 4 is a diagram showing a shift pattern at the time of deceleration when the shift stage is the second speed.

FIG. 5 is a diagram showing a shift pattern at the time of deceleration when the shift stage is the third speed.

FIG. 6 is a diagram showing a shift pattern at the time of deceleration when the shift stage is the fourth speed.

FIG. 7 is a diagram showing a shift pattern during normal traveling.

FIG. 8 is a flowchart illustrating engagement control of an overrun clutch.

FIG. 9 is a flowchart illustrating line pressure control.

FIG. 10: Downhill map that defines the line pressure P _L corresponding to the vehicle speed VSP

FIG. 11 is a map that defines a correction coefficient K for correcting the line pressure P _L based on the gradient resistance.

FIG. 12: Line pressure P corresponding to throttle opening TVO
Map for downhill and downhill shift with _L defined

FIG. 13 is a map for normal speed change in which the line pressure P _L corresponding to the vehicle speed VSP is set.

FIG. 14 is an operation explanatory view of the transmission gear mechanism 4 (D range 1
Speed)

FIG. 15 is an explanatory diagram of the operation of the transmission gear mechanism 4 (D range 2
Speed)

FIG. 16 is an operation explanatory view of the transmission gear mechanism 4 (D range 3
Speed)

FIG. 17 is an explanatory diagram of the operation of the transmission gear mechanism 4 (D range 4;
Speed)

[Explanation of symbols]

 1 Engine 2 Automatic Transmission 3 Torque Converter 5 Hydraulic Mechanism 6 Throttle Sensor 7 Vehicle Speed Sensor 8a Inhibitor Switch 50 Control Unit 70 Gradient Sensor 80 Oil Pump 82 Electromagnetic Valve

Claims (2)

[Claims] 1. A line pressure control device for an automatic transmission in a vehicle in which an automatic transmission with a torque converter is connected to an output shaft of an engine, a vehicle speed detecting means for detecting a vehicle speed, and a vehicle deceleration state for detecting a deceleration state of the vehicle. Detecting means, line pressure setting means for setting a line pressure based on the detected vehicle speed, gradient resistance detecting means for detecting gradient resistance of the vehicle road surface, and deceleration state is detected by the vehicle deceleration state detecting means. And a line pressure correction setting means for correcting and setting the line pressure set by the line pressure setting means on the basis of the gradient resistance detected by the gradient resistance detecting means. Line pressure control device for automatic transmission. 2. The line pressure control device for an automatic transmission for a vehicle according to claim 1, wherein the gradient resistance detecting means is a gradient sensor.