JP2658651B2 - Line pressure control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line pressure control device capable of optimizing the line pressure of an automatic transmission for a plurality of types of engines having different output characteristics.

[0002]

2. Description of the Related Art In an automatic transmission, various frictional elements (clutches, brakes, etc.) are selectively hydraulically actuated by a line pressure to select a predetermined gear position (gear position), and other operating elements are changed by changing the operating frictional element. A shift to a shift speed can be performed.
Here, for example, when the shift is a downshift that performs a select operation of two ranges while driving in the D range, if the shift is a downshift, the page A of “5E-AT Automatic Transaxle Maintenance Manual (A261C14)” issued by Nissan Motor Co., Ltd. -36, A-37
In the automatic transmission described in (1), a so-called backup control for selecting a line pressure control characteristic in accordance with a gear position after shifting is performed.

[0003]

Generally, automatic transmissions have the following features.
The present invention is applied to various types of engines having different output characteristics, such as a type capable of obtaining a large torque at a low rotation and a type capable of obtaining a large torque at a high rotation. At this time, the hydraulic pressure supplied to each friction element of the automatic transmission is determined by the throttle opening degree (engine load) of the engine, and the torque band shared by each gear differs for each type of shift (shift point). Become. On the other hand, in the conventional automatic transmission described in the maintenance manual (the same applies to the automatic transmission described in JP-A-62-233554), when applying to a plurality of types of engines, As described on page A-36, during steady state except for the above-mentioned downshift,
By looking up the line pressure control characteristic map based on, for example, the throttle opening, D, 2,
During the selection of one range (during forward running), the same hydraulic pressure was set for all gear positions, so that the optimum line pressure could not be set at all gear positions. Insufficiency may occur, in which case, for example, a hardware method of increasing or decreasing the number of crack plates has been used. However, such a hardware method has limitations because it involves a change in the design of the mechanical components of the automatic transmission.
If the excess cannot be eliminated, friction will increase.

According to the present invention, the minimum pressure of the line pressure control characteristic selected from the plurality of line pressure control characteristics according to the current gear position is increased during operation of the engine brake from a value during non-operation of the engine brake. By doing so, an object is to solve the above-mentioned problem.

[0005]

SUMMARY OF THE INVENTION To this end, a line pressure control device for an automatic transmission according to the present invention includes a backup control for increasing a line pressure so as to compensate for a coast torque during a selection operation to an engine brake operation range; A gear that detects the current gear position in an automatic transmission that operates using the line pressure controlled by the line pressure control including the cutback control that increases the line pressure to compensate for the torque amplification by the torque converter during start acceleration. Position detecting means, and control characteristic selecting means for selecting a line pressure control characteristic applicable to the current gear position detected from a plurality of line pressure control characteristics set for each gear position,
An engine brake detecting means for detecting whether or not the engine brake is operating, wherein both the backup control and the cutback control are not operating, and the engine brake detecting means detects that the engine brake is operating. In some cases, the minimum pressure of the line pressure control characteristic is set to be larger than the value when the engine brake is not operating.

[0006]

Various friction elements of the automatic transmission are operated by supplying a hydraulic pressure based on a line pressure controlled according to, for example, a throttle opening by a line pressure control including a backup control and a cutback control. Meanwhile, the gear position detecting means detects the current gear position, and the control characteristic selecting means selects the line pressure control characteristic applicable to the current gear position detected from the plurality of line pressure control characteristics set for each gear position. Is selected, and the line pressure is adjusted to an optimum value according to the running state at that time. At this time, when both the backup control and the cutback control are not operating and the engine brake detecting means detects that the engine brake is operating, the minimum pressure of the line pressure control characteristic is set to a value during the non-operation of the engine brake. , It is possible to realize a line pressure suitable for an engine braking request such as continuous downhill running where the friction element requires a larger engagement capacity.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a first embodiment of a line pressure control device for an automatic transmission according to the present invention, in which 1 denotes an engine, and 2 denotes an automatic transmission. The engine 1 is operated with an ignition timing and a fuel injection amount determined by an engine control computer (ECCS) 3. Therefore, the signal respectively input from the throttle sensor 5 for detecting the signal and engine throttle opening TVO from the engine speed sensor 4 for detecting engine speed N _E to ECCS3. The automatic transmission 2 receives the power of the engine 1 via the torque converter 6 and transmits the power to the output shaft 7 at a gear ratio corresponding to the selected gear position (gear position) so that the vehicle can run. A control valve 8 for controlling the speed of the automatic transmission 2 is provided.
A third shift solenoid 9-1, 9-2, 9-3, an overrun solenoid 10, and a line pressure solenoid 11. The ON and OFF of these solenoids 9-1 to 9-3, 10 and 11 are controlled by an automatic transmission control computer (ATCU) 12, and the shift solenoids 9-1 to 9-3 are turned ON in the combinations shown in Table 1. The frictional element (not shown) of the automatic transmission 2 is selectively hydraulically actuated by the line pressure by turning off the gear, thereby selecting a corresponding gear position (gear position).

[0008]

[0009] Control of the line pressure is performed by ATCU 12 controls the drive duty D _PL of the line pressure solenoid 11. For the line pressure control and the shift control,
The ATCU 12 receives a signal relating to the throttle opening TVO from the sensor 5, an input speed N _T of the automatic transmission from the sensors 13 and 14, and an output speed N _O of the output shaft 7 (this is the vehicle speed).
Signals used to determine the VSP)
Select range RNG from inhibitor switch 15
(Selection lever selection position; D, 2, 1, R, N, P range) and oil temperature TE from oil temperature sensor 16
Also input signals related to MP. The ATCU 12 executes the control program of FIG. 2 based on these input signals to perform the line pressure control according to the present invention.

That is, in the control program of the main routine shown in FIG. 2, which is repeatedly executed by a periodic interruption every predetermined period, first, at step 101, the vehicle speed VSP is read based on the output rotation speed N _O from the output rotation sensor 14, and
At 102, 103, and 104, the throttle opening TVO from the throttle sensor 5, the inhibitor switch 15, and the oil temperature sensor 16, respectively.
, Select range RNG (RNG = D range, 2 ranges,-
-), And read the oil temperature TEMP. In the next step 105, it is determined whether or not the backup condition is satisfied. This backup condition is described on page A of the 5E-AT maintenance manual.
-36, A-37 are conditions for implementing the backup control. For example, D range 3rd speed or higher to 2 range 2
This corresponds to the case where the operation for selecting the speed below the speed and the operation for releasing the accelerator pedal (throttle opening TVOO0) are performed simultaneously. If the backup condition is satisfied, the vehicle speed VS is corrected in step 106 to correct the engine coast torque when the engine brake is activated by the select operation.
Backup control is performed to select a line pressure control characteristic map according to P and the type of shift (for example, third speed → second speed). In addition, this backup control is performed based on a map in which the line pressure is set to be higher (for example, the third speed is higher than the second speed, and the first speed is higher than the second speed) in consideration of the driving force applied to the friction element, for example, as the shift speed is shifted to the lower speed side. .

On the other hand, if the backup condition is not satisfied, it is determined in step 107 whether the cutback condition is satisfied. The cutback conditions are as follows: when starting (at low speed;
(For example, until the vehicle speed reaches 10 km / h) This is a condition for executing cutback control for correcting the torque amplification due to the operation of the torque converter at the start of engine torque generation. For example, the vehicle speed VSP is the cutback execution vehicle speed VCBO
N (for example, 10 km / h) (VSP <VCBON) Cutback control is performed, and the cutback release vehicle speed VCBOFF
(For example, 12 km / h) or more (VSP ≧ VCBOFF), the cutback control is released, and when the oil temperature TEMP falls below the cutback inhibition temperature TEMPCBINH (TEMP ≦ TEMPCBINH).
) Cutback control is prohibited regardless of the vehicle speed VSP. If the cutback condition is satisfied, cutback control is performed in step 108. This cutback control is almost the same as that described in the new Gemini (JT type) new car manual issued by Isuzu Motors Ltd. Second Service Department. By switching to the cutback line pressure characteristic map, It aims to increase the pressure (However, using this map, the throttle opening TVO
If the line pressure at the time of cutback determined by the above is lower than the line pressure determined by the TVO using the map at the steady state, a large select is performed to select the line pressure at the steady state.

If neither the backup control nor the cutback control is performed, the gear position GP is read in step 109 following NO in step 107. The gear position is read by an internal signal of the ATCU 12 which monitors the ON / OFF state of the shift solenoids 9-1, 9-2, 9-3.
As shown in the figure, solenoid 9-1 is ON, 9-2 is ON, and 9-3 is OF
In the case of F, the first speed (GP = 1) is set (at step 109, the ATCU 12 functions as gear position detecting means). In the next step 110, it is determined whether or not the engine brake is activated. The ATCU which monitors the ON / OFF state of the overrun solenoid 10
Turn off the overrun solenoid to turn on the overrun clutch (not shown) using the internal signal of 12.
The engine brake mode (OVERON = 1) is set when the throttle opening TVO is substantially zero, and the non-engine brake mode (OVERON = 0) is set otherwise.

In the next step 111, the line pressure control characteristic map is looked up based on the GP, TVO, VSP, and OVERON obtained as described above (in this step 111, the ATCU 12 functions as a control characteristic selecting means). Do).
In this lookup, first, a map applicable to the current gear position GP is set for each gear position as shown in FIG. 3 (a) for the second speed, and FIG. 3 (b) for the third and fourth speeds. From the plurality of line pressure control characteristic maps, and then, in the map, search for the characteristic of the dotted line in the engine brake mode and the characteristic of the solid line in the non-engine brake mode based on the throttle opening TVO. Pressure P
Seeking _L, even 3 obtains a speed proportional amount of the line pressure P _L by map (c), the the sum of both the line pressure P _L. The line pressure P _L in the next step 112, converts the duty D _PL of the line pressure solenoid 11. This conversion is performed, for example, by looking up a line pressure duty conversion map shown in FIG. 3D using P _L , and the obtained duty D _PL is output to the line pressure solenoid 11 in step 113.

In the above-described line pressure control of the present embodiment, the backup control is performed at the time of the select operation downshift where the backup condition is satisfied, and the cutback control is performed at the time of starting (at low speed) where the cutback condition is satisfied. Then, in addition to performing the same line pressure control as in the conventional example, the steady-state line pressure control targeted by the present invention is also performed. That is, when the vehicle travels forward when the select range is the D, 2,1 range (RNG = D, 2,1), the line pressure control characteristic map is selectively used in accordance with the current gear position GP. By setting the map to match the output characteristics of the engine to be applied, it is possible to adjust each line to the optimal line pressure for each gear position, and the operating oil pressure of the friction element that selectively operates corresponding to each gear position can be adjusted. The pressure is reduced, friction is reduced, and fuel efficiency is improved.
Also, since the optimal line pressure is obtained as described above,
It is not necessary to adjust the number of clutch plates of the specific friction element as in the conventional example, and it is possible to apply a common automatic transmission to a plurality of types, thereby improving design flexibility. Further, in the above line pressure control, when the engine brake is operated (engine brake mode; OVERON = 1), FIG.
As shown in (a) and (b), the minimum pressure is set higher than when the engine brake is not operating (non-engine brake mode; OVERON = 0). The preferred line pressure is obtained.

[0015]

As described above, the line pressure control device for an automatic transmission according to the present invention provides a line pressure control characteristic applicable to the current gear position from among a plurality of line pressure control characteristics set for each gear position. When selecting and adjusting the line pressure to the optimum value according to the running state at that time, it is determined that both the backup control and the cutback control are not operating and the engine brake detecting means is operating the engine brake. When it is detected, the minimum pressure of the line pressure control characteristic is increased from the value during non-operation of the engine brake. Suitable line pressure can be realized.

[Brief description of the drawings]

FIG. 1 is a first view of a line pressure control device for an automatic transmission according to the present invention.
It is a figure showing composition of an example.

FIG. 2 is a flowchart showing a line pressure control program executed by an automatic transmission control computer in the same example.

FIGS. 3A to 3D are characteristic diagrams illustrating line pressure control characteristics in the same example.

[Explanation of symbols]

 Reference Signs List 1 engine 2 automatic transmission 3 engine control computer (ECCS) 5 throttle sensor 8 control valve 9-1, 9-2, 9-3 shift solenoid 10 overrun solenoid 11 line pressure solenoid 12 automatic transmission control computer (ATCU) 13 Input rotation sensor 14 Output rotation sensor 15 Inhibitor switch 16 Oil temperature sensor

Claims (1)

(57) [Claims] 1. A backup control for increasing a line pressure so as to compensate for a coast torque when a select operation to an engine brake operation range is performed, and a cutback control for increasing a line pressure so as to compensate for a torque amplification by a torque converter during start acceleration. In an automatic transmission that operates using the line pressure controlled by the line pressure control including the original pressure, a gear position detecting means for detecting a current gear position, and a plurality of line pressure control characteristics set for each gear position are detected. Control characteristic selecting means for selecting a line pressure control characteristic applicable to the current gear position, and engine brake detecting means for detecting whether or not the engine brake is operating, wherein both the backup control and the cutback control operate. And the engine brake detecting means is not When it is detected that is in operation, characterized in that the minimum pressure of the line pressure control characteristics so as to increase than the value of the engine brake inoperative during,
Line pressure control device for automatic transmission.