JP4622501B2 - Control device for automatic transmission - Google Patents

Description

  The present invention relates to a control device for an automatic transmission, and more particularly to a control device for an automatic transmission in which neutral control is performed.

  An automatic transmission mounted on a vehicle is connected to an engine via a torque converter or the like, and automatically changes a gear ratio (travel speed stage) based on, for example, an accelerator opening and a vehicle speed. Generally, a vehicle having an automatic transmission is provided with a shift lever operated by a driver, and a shift position (for example, a reverse travel position, a neutral position, a forward travel position) is set based on the shift lever operation. The automatic shift control is performed within the thus set shift position (usually in the forward travel position).

  In a vehicle having such an automatic transmission, in a state where the forward traveling position is set and the vehicle is stopped, the driving force from the idling engine is transmitted to the transmission via the torque converter, which is the wheel. Therefore, a so-called creep phenomenon occurs. Creep phenomenon is very useful under certain conditions, such as smooth starting from a stop on an uphill road, but it is an unnecessary phenomenon when you want to keep the vehicle stopped, and it activates the vehicle brake To suppress the creep force. That is, the creep force from the engine is suppressed by the brake, and there is a problem that the fuel consumption of the engine is reduced accordingly.

  For this reason, in the forward travel position, when the brake pedal is depressed and the brake is activated, and the accelerator is almost fully closed and the vehicle is stopped, the transmission remains in the forward travel position to neutral. It has been proposed to improve fuel efficiency in a near neutral state.

  Such neutral control is executed by disengaging the clutch of the automatic transmission that is engaged when the vehicle is running. The clutch of the automatic transmission is operated by the hydraulic pressure of the hydraulic oil. Since the viscosity of hydraulic oil changes with temperature, the response during neutral control depends on the oil temperature. When the oil temperature is low and the clutch is not quickly engaged or disengaged due to the high viscosity of the hydraulic oil, the neutral control is not performed properly. Therefore, the neutral control is limited according to the oil temperature. There is a need. Further, when the engine coolant temperature is low, the idling engine speed is not stable because of the idling engine speed being set high or friction due to the viscosity of the engine lubricating oil. Therefore, it is necessary to limit the neutral control according to the temperature of the cooling water of the engine.

  Japanese Patent Laid-Open No. 11-230324 (Patent Document 1) discloses a control device for an automatic transmission that performs neutral control in accordance with oil temperature and water temperature. The automatic transmission control device described in this publication is in a neutral state when the temperature of engine coolant is equal to or lower than a predetermined value and when the oil temperature of the automatic transmission is equal to or lower than a predetermined value. Prohibit migration.

According to the automatic transmission control device described in this publication, when the neutral control is executed, the responsiveness of the automatic transmission is poor, and the controllability of the neutral control is deteriorated due to the high idle speed. Can be suppressed.
Japanese Patent Laid-Open No. 11-230324

  However, in the control device for an automatic transmission described in Japanese Patent Application Laid-Open No. 11-230324, since neutral control is prohibited at low oil temperature and low water temperature, an area for executing neutral control is expanded. There was a problem that fuel consumption could not be further improved.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an automatic transmission control device capable of improving fuel consumption.

  A control device for an automatic transmission according to a first aspect controls an automatic transmission having a friction engagement element that is engaged when the vehicle starts. In the control device, when a predetermined condition is satisfied, permission means for permitting execution of neutral control for releasing the friction engagement element, and the friction engagement element is changed from the engagement state to the release state. When the adjustment means for adjusting the engagement pressure of the friction engagement element and the adjustment pressure of the friction engagement element by the adjustment means are adjusted based on the time until the above, the predetermined condition is relaxed And mitigation means.

  According to the first aspect of the present invention, when the neutral control is executed at the time of low water temperature and the viscosity of the engine lubricating oil is high and the load due to friction is large, the output of the engine before the friction engagement element is released. When the output is reduced (when the output is reduced to a level suitable for neutral control), there is a risk of stalling due to the load caused by friction and the load caused by the automatic transmission. Also, when neutral control is executed when the oil temperature is low or the viscosity is high, and the responsiveness of the frictional engagement element is poor, the engine output is reduced before the frictional engagement element is released. There is a risk of stalling. Therefore, predetermined conditions (for example, the condition that the oil temperature is higher than the predetermined oil temperature, the condition that the water temperature is higher than the predetermined water temperature, and the viscosity of the hydraulic oil are lower than the predetermined viscosity. The neutral control is permitted to be executed when the above condition is satisfied. The engagement pressure of the friction engagement element is adjusted by the adjusting means. When the time until the frictional engagement element is changed from the engaged state to the released state is longer than a predetermined time, the engagement pressure of the frictional engagement element is lowered. When such adjustment of the engagement pressure is performed, the time from the engagement state to the release state is shortened, and even if the neutral control is executed at the time of low oil temperature, low water temperature, and high viscosity, the engine stall is reduced. It is suppressed. Therefore, a predetermined condition for permitting neutral control is relaxed. Thereby, the execution area | region of neutral control can be expanded. Therefore, fuel consumption can be improved. As a result, it is possible to provide an automatic transmission control device capable of improving fuel consumption.

  In the control apparatus for an automatic transmission according to the second invention, in addition to the configuration of the first invention, the predetermined condition is that the temperature of the hydraulic oil of the friction engagement element is higher than the predetermined temperature. It is a condition. The relaxation means includes means for lowering the predetermined temperature when the adjustment pressure of the friction engagement element is adjusted by the adjustment means.

  According to the second invention, neutral control can be executed from a state where the oil temperature is lower. Therefore, the execution area of neutral control can be expanded. As a result, fuel consumption can be improved.

  In the automatic transmission control apparatus according to the third aspect of the invention, in addition to the configuration of the first aspect, the predetermined condition is that the temperature of the cooling water of the power source connected to the friction engagement element is predetermined. The temperature is higher than the above temperature. The relaxation means includes means for lowering the predetermined temperature when the adjustment pressure of the friction engagement element is adjusted by the adjustment means.

  According to the third invention, the neutral control can be executed from a state where the water temperature is lower. Therefore, the execution area of neutral control can be expanded. As a result, fuel consumption can be improved.

  In the control apparatus for an automatic transmission according to the fourth aspect of the invention, in addition to the configuration of the first aspect, the friction engagement element is operated by the hydraulic pressure of the hydraulic oil. The predetermined condition is a condition that the viscosity of the hydraulic oil is lower than the predetermined viscosity. The relaxation means includes means for increasing the predetermined viscosity when the adjustment pressure of the friction engagement element is adjusted by the adjustment means.

  According to the fourth invention, neutral control can be executed from a state in which the viscosity is higher. Therefore, the execution area of neutral control can be expanded. As a result, fuel consumption can be improved.

  In the control device for an automatic transmission according to the fifth aspect of the invention, in addition to the configuration of any one of the first to fourth aspects, the adjusting means has a time until the friction engagement element changes from the engaged state to the released state. Means for lowering the engagement pressure of the friction engagement element if longer than a predetermined time.

  According to the fifth aspect of the present invention, it is possible to shorten the time until the friction engagement element changes from the engagement state to the release state, and to release the friction engagement element quickly.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, a power train of a vehicle including a control device according to an embodiment of the present invention will be described. The control device according to the present embodiment is realized by, for example, ECU 1000 shown in FIG. Hereinafter, the automatic transmission will be described as a belt type continuously variable transmission. The automatic transmission is not limited to a belt type continuously variable transmission, but may be an automatic transmission composed of a planetary gear mechanism or an automatic transmission composed of a constantly meshing gear.

  As shown in FIG. 1, the power train of the vehicle includes an engine 100, a torque converter 200, a forward / reverse switching device 290, a belt-type continuously variable transmission (CVT) 300, a differential gear 800, and the like. The ECU 1000 and a hydraulic control unit 1100 are configured.

  The output shaft of engine 100 is connected to the input shaft of torque converter 200. Engine 100 and torque converter 200 are connected by a rotating shaft. Therefore, output shaft rotational speed NE (engine rotational speed NE) of engine 100 detected by the engine rotational speed sensor and input shaft rotational speed (pump rotational speed) of torque converter 200 are the same.

  The torque converter 200 includes a lock-up clutch 210 that directly connects the input shaft and the output shaft, a pump impeller 220 on the input shaft side, a turbine impeller 230 on the output shaft side, and a one-way clutch 250. It is comprised from the stator 240 which expresses an amplification function. Torque converter 200 and CVT 300 are connected by a rotating shaft. The output shaft rotational speed NT (turbine rotational speed NT) of the torque converter 200 is detected by the turbine rotational speed sensor 400.

  CVT 300 is connected to torque converter 200 via forward / reverse switching device 290. The CVT 300 includes an input side primary pulley 500, an output side secondary pulley 600, and a metal belt 700 wound around the primary pulley 500 and the secondary pulley 600. Primary pulley 500 includes a fixed sheave fixed to the primary shaft and a movable sheave supported on the primary shaft so as to be slidable only. The secondary pulley 700 includes a fixed sheave fixed to the secondary shaft and a movable sheave supported on the secondary shaft so as to be slidable only. The primary pulley rotational speed NIN of the CVT 300 is detected by the primary pulley rotational speed sensor 410, and the secondary pulley rotational speed NOUT is detected by the secondary pulley rotational speed sensor 420.

  These rotation speed sensors are provided to face the rotation detection gear teeth attached to the rotation shafts of the primary pulley 500 and the secondary pulley 600 and the drive shaft connected thereto. These rotational speed sensors are sensors capable of detecting a slight rotation of the primary pulley 500 serving as an input shaft and the secondary pulley 600 serving as an output shaft of the CVT 300. For example, the rotational speed sensors are generally referred to as semiconductor sensors. This is a sensor using a magnetoresistive element.

  The forward / reverse switching device 290 includes a double pinion planetary gear, a reverse (reverse) brake B1 and an input clutch C1. In the planetary gear, its sun gear is connected to the input shaft, the carrier CR supporting the first and second pinions P1, P2 is connected to the primary side fixed sheave, and the ring gear R is a reverse friction engagement element. The reverse brake B1 is connected, and an input clutch C1 is interposed between the carrier CR and the ring gear R. The input clutch 310 is also called a forward clutch or a forward clutch, and is always used in an engaged state when a vehicle other than the parking (P) position, the R position, and the N position moves forward.

  Control in which the input clutch 310 is released to a predetermined slip state when the vehicle is in the D position and stops in a state that satisfies a predetermined condition is referred to as neutral control.

  In the neutral control, since the input clutch 310 is released (including the slip state), the load of the torque converter 200 on the engine 100 is reduced accordingly. Therefore, in neutral control, the output of engine 100 is reduced to an output suitable for neutral control.

  Therefore, when the neutral control is executed when the temperature of the cooling water of the engine 100 (water temperature) is low and the viscosity of the lubricating oil is high and the load due to friction is large, if the release of the input clutch 310 is delayed, the load due to friction There is a possibility that the engine stalls due to the load by the torque converter 200. In order to suppress engine stall, neutral control is permitted when the water temperature is higher than a predetermined neutral control permission water temperature.

  In addition, when the oil temperature of the hydraulic fluid of the input clutch 310 is low, the response of the input clutch 310 is poor, and the time required until the input clutch 310 is released from the engaged state tends to be long. Therefore, neutral control may be permitted when the oil temperature is higher than a predetermined neutral control permission oil temperature. Further, for the same reason, neutral control may be permitted when the viscosity of the hydraulic oil is lower than a predetermined neutral control permission viscosity.

  As shown in FIG. 1, ECU 1000 receives a signal representing turbine rotational speed NT from turbine rotational speed sensor 400, and a signal representing primary pulley rotational speed NIN from primary pulley rotational speed sensor 410, from secondary pulley rotational speed sensor 420. Signals representing secondary pulley rotation speed NOUT are input.

  As shown in FIG. 1, the hydraulic control unit 1100 includes a shift speed control unit 1110, a belt clamping pressure control unit 1120, a lockup engagement pressure control unit 1130, a clutch pressure control unit 1140, and a manual valve 1150. Including. From the ECU 1000, the shift control duty solenoid (1) 1200, the shift control duty solenoid (2) 1210, the belt clamping pressure control linear solenoid 1220, the lockup solenoid 1230, and the lockup engagement from the ECU 1000. A control signal is output to the pressure control duty solenoid 1240. Details of this hydraulic circuit are disclosed in Japanese Patent Laid-Open No. 2002-181175, and therefore detailed description thereof will not be repeated here.

  The structure of ECU 1000 that controls these power trains will be described in more detail with reference to FIG. As shown in FIG. 2, ECU 1000 includes an engine ECU 1010 that controls engine 100, an ECT (Electronic Controlled Automatic Transmission) _ECU 1020 that controls CVT 300, and a VSC (Vehicle Stability Control) _ECU 1030.

  In addition to the input / output signals shown in FIG. 1, the ECT_ECU 1020 receives a signal indicating that the driver is stepping on the brake pedal from the stop lamp switch, and the G sensor when the vehicle stops on an uphill road or the like. Each of the signals representing the slope of the uphill road is input. Further, the engine ECU 1010 receives from the accelerator opening sensor a signal indicating the opening degree of the accelerator pedaled by the driver, from the throttle position sensor, a signal indicating the opening degree of the electromagnetic throttle, from the engine speed sensor, Signals representing the number of revolutions (NE) are respectively input. Engine ECU 1010 and ECT_ECU 1020 are connected to each other.

  Further, the ECT_ECU 1020 receives a brake pressure signal representing the brake hydraulic pressure from the VSC_ECU 1030.

  In hydraulic control unit 1100, belt clamping pressure control unit 1120 controls the clamping pressure of belt 700 of CVT 300 based on the control signal output from ECT_ECU 1020 to linear solenoid 1220 for belt clamping pressure control. The clamping pressure of the belt 700 is a pressure at which the pulley and the belt are in contact with each other.

  Further, when the neutral control is executed, the clutch pressure control unit 1140 is applied to the engagement pressure of the input clutch 310 (supplied to the input clutch 310 based on the control signal output from the ECT_ECU 1020 to the linear solenoid 1220 for belt clamping pressure control. Control). The hydraulic pressure controlled by the clutch pressure control unit 1140 is supplied to the input clutch 310 via the manual valve 1150.

  As shown in FIG. 3, when the neutral control execution condition is satisfied at time T (1) accompanying the deceleration of the vehicle, the neutral control is executed, and the target clutch hydraulic pressure of the input clutch 310 is temporarily set to the neutral control start hydraulic pressure. The

  Thereafter, at time T (2), the target clutch hydraulic pressure is gradually reduced after the target clutch hydraulic pressure is reduced stepwise. As the target hydraulic pressure is gradually reduced, the input clutch 310 gradually shifts to the disengaged state, and at the time T (3), the turbine speed NT starts to increase.

  Here, the engagement pressure of the input clutch 310 varies among individuals. Therefore, even if the same neutral control start hydraulic pressure is used, the engagement pressure of the input clutch 310 may be different among individuals.

  If the engagement pressure is low, the input clutch 310 may be released before the output of the engine 100 is reduced (the output is suitable for the neutral control) when the neutral control is executed. In this case, the load on engine 100 may be suddenly reduced and engine 100 may be blown up. Therefore, normally, the neutral control start hydraulic pressure in the initial state at the time of completion of the assembly of the vehicle is set to be high.

  However, if the neutral control start hydraulic pressure is set to a high value, the engagement pressure of the input clutch 310 is higher than necessary and the efficiency is poor, which adversely affects fuel consumption. Further, when the neutral control is executed, the release of the input clutch 310 is delayed more than necessary. Therefore, during the neutral control, the neutral control start hydraulic pressure is learned based on the time until the input clutch 310 changes from the engaged state to the released state.

  That is, if the time ΔT (1) from the time T (2) to the time T (3) is longer than the predetermined time ΔT (0), as shown by a one-dot chain line in FIG. Is reduced by a predetermined amount.

  Thereby, after execution of neutral control, turbine rotational speed NT begins to rise at time T (4). Therefore, the time until the input clutch 310 is changed from the engaged state to the released state is shortened from ΔT (1) to ΔT (2).

  Thus, when the time until the input clutch 310 is changed from the engaged state to the released state is longer than the predetermined time, the neutral control start hydraulic pressure is reduced by a predetermined amount, and the neutral control start is started. Hydraulic learning is performed.

  When the number of times this learning is performed is less than 3 times from the initial state (when the number of times that the neutral execution condition is satisfied is less than 3 times), high-speed learning in which the amount of reduction in the neutral control start hydraulic pressure is larger than usual is performed. Done. Note that high-speed learning is not limited to less than three times from the initial state.

  With reference to FIG. 4, a control structure of a program executed in ECT_ECU 1020 which is the control device according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, ECT_ECU 1020 determines whether or not high-speed learning of the neutral control start hydraulic pressure has been completed. For example, when the neutral control start hydraulic pressure is learned three or more times from the initial state, it is determined that the high speed learning is completed. It should be noted that when the reduction amount (correction amount) of the neutral control start hydraulic pressure becomes a predetermined value, or when the neutral control start hydraulic pressure becomes a predetermined value, it may be determined that the high-speed learning has been completed. . If the fast learning is completed (YES in S100), the process proceeds to S120. If not (NO in S100), the process proceeds to S110.

  In S110, ECT_ECU 1020 sets the neutral control permission water temperature to “A”. In S120, ECT_ECU 1020 sets the neutral control permission water temperature to “B (B <A)”.

  An operation of ECT_ECU 1020 of the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  If the number of times that the neutral control start hydraulic pressure has been learned is less than 3 at the time of activation of the vehicle system (NO in S100), the neutral control permission water temperature is set to “A” (S110).

  On the other hand, when the neutral control start hydraulic pressure is learned three or more times and high-speed learning is completed (YES in S100), the time until input clutch 310 is released from the engaged state is shortened. Thus, input clutch 310 can be released according to the timing at which the output of engine 100 is reduced by executing neutral control. In this case, since the viscosity of the lubricating oil of the engine 100 is high, it can be said that even if the neutral control is executed at a low water temperature where the friction is large, it is difficult to stall. Therefore, the neutral control permission water temperature is reduced from “A” to “B” (S120), and the neutral control execution area is expanded. As a result, fuel consumption can be improved.

  As described above, according to the ECT_ECU that is the control device according to the present embodiment, when the high speed learning is completed, the time until the input clutch is changed from the engaged state to the released state is shortened, and the neutral is achieved at low water temperature. The engine stall can be suppressed even when the control is executed. Therefore, the neutral control permission water temperature is lowered after the high-speed learning is completed. Thereby, the execution area | region of neutral control can be expanded to the low water temperature area | region, and a fuel consumption improvement can be aimed at.

  In this embodiment, when the high-speed learning is completed, the neutral control permission water temperature is lowered. However, when the oil temperature of the hydraulic oil of the input clutch 310 is higher than the neutral control permission oil temperature, the neutral control permission water temperature is decreased. When the execution is permitted, the neutral control permission oil temperature may be lowered when the high-speed learning is completed.

  Further, when the execution of neutral control is permitted when the viscosity of the hydraulic oil of the input clutch 310 is lower than the neutral control permission viscosity, the neutral control permission viscosity may be increased when the high-speed learning is completed. .

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram of the control apparatus which concerns on embodiment of this invention. FIG. 2 is a detailed view of the ECU shown in FIG. 1. It is a figure which shows transition of the target clutch hydraulic pressure and turbine rotation speed NT in neutral control. It is a flowchart which shows the control structure of the program which ECT_ECU of the control apparatus which concerns on embodiment of this invention performs.

Explanation of symbols

  100 engine, 200 torque converter, 210 lock-up clutch, 220 pump impeller, 230 turbine impeller, 240 stator, 250 one-way clutch, 290 forward / reverse switching device, 300 CVT, 310 input clutch, 400 turbine speed sensor, 410 primary Pulley rotational speed sensor, 420 Secondary pulley rotational speed sensor, 500 primary pulley, 600 secondary pulley, 700 belt, 800 differential gear, 1000 ECU, 1010 engine ECU, 1020 ECT_ECU, 1100 hydraulic control unit, 1110 shift speed control unit, 1120 belt Clamping pressure control unit, 1130 Lock-up engagement pressure control unit, 1140 Clutch pressure control unit, 1150 Manual valve, 1200 Shift control duty solenoid (1), 1210 Shift control duty solenoid (2), 1220 Belt clamping pressure control linear solenoid, 1230 Lock-up solenoid, 1240 Lock-up engagement pressure control duty solenoid.

Claims (4)

A control device for an automatic transmission having a friction engagement element that is engaged when the vehicle starts,
Permission means for permitting execution of neutral control for releasing the friction engagement element when a predetermined condition is satisfied;
Adjusting means for adjusting the engagement pressure of the friction engagement element based on the time until the friction engagement element changes from the engaged state to the released state;
A relaxation means for relaxing the predetermined condition when the adjustment pressure of the friction engagement element is adjusted by the adjustment means;
The predetermined condition is a condition that the temperature of the hydraulic oil of the friction engagement element is higher than a predetermined temperature,
It said reducing means, the case where the adjustment of the engagement pressure of the frictional engagement elements by adjusting means has been performed, including means for lowering the predetermined temperature, the control device of the automatic transmission. A control device for an automatic transmission having a friction engagement element that is engaged when the vehicle starts,
Permission means for permitting execution of neutral control for releasing the friction engagement element when a predetermined condition is satisfied;
Adjusting means for adjusting the engagement pressure of the friction engagement element based on the time until the friction engagement element changes from the engaged state to the released state;
A relaxation means for relaxing the predetermined condition when the adjustment pressure of the friction engagement element is adjusted by the adjustment means;
The predetermined condition is a condition that the temperature of the cooling water of the power source connected to the friction engagement element is higher than a predetermined temperature,
It said reducing means, the case where the adjustment of the engagement pressure of the frictional engagement elements by adjusting means has been performed, including means for lowering the predetermined temperature, the control device of the automatic transmission. A control device for an automatic transmission having a friction engagement element that is engaged when the vehicle starts,
Permission means for permitting execution of neutral control for releasing the friction engagement element when a predetermined condition is satisfied;
Adjusting means for adjusting the engagement pressure of the friction engagement element based on the time until the friction engagement element changes from the engaged state to the released state;
A relaxation means for relaxing the predetermined condition when the adjustment pressure of the friction engagement element is adjusted by the adjustment means;
The friction engagement element is operated by hydraulic pressure of hydraulic oil,
The predetermined condition is a condition that the viscosity of the hydraulic oil is lower than a predetermined viscosity,
It said reducing means, the case where the adjustment of the engagement pressure of the frictional engagement elements by adjusting means has been performed, including means for increasing the predetermined viscosity, the control device of the automatic transmission. The adjusting means includes means for lowering the engagement pressure of the friction engagement element when the time until the friction engagement element is changed from the engagement state to the release state is longer than a predetermined time. The control device for an automatic transmission according to any one of claims 1 to 3 .

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