JPH0215747B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic transmission for a vehicle that can improve driving performance (driveability) during warm-up.

Automatic transmissions are equipped with a direct coupling clutch installed in parallel with a hydraulic torque converter, and transmit engine power to the drive wheels at multiple reduction ratios, including overdrive, thereby improving fuel efficiency and achieving good high speeds. I'm trying to drive. In conventional automatic transmissions, the engagement of the direct coupling clutch and the shift-up to overdrive are determined in relation to the vehicle speed and the opening of the intake system throttle valve, regardless of whether it is warmed up or not. As for the intake system throttle valve opening, the direct coupling clutch is engaged and shifted to overdrive even during warm-up.
Because engine power is transmitted to the drive wheels at a small reduction ratio, driving performance during warm-up is degraded.

An object of the present invention is to provide an automatic transmission control method that can improve driving performance during warm-up and further suppress fuel consumption during warm-up.

In order to achieve this object, according to the automatic transmission control method of the present invention, the total number of revolutions from the start of the engine is detected, and if the total number of revolutions is less than a predetermined value, the direct coupling clutch is activated. Executes warm-up stabilization control that prohibits engagement or shifting to the highest gear.

Embodiments of the present invention will be described with reference to the drawings.

The intake system is provided with, in order from upstream, an air cleaner 1, an air flow meter 2 that detects the intake air flow rate, a throttle valve 3 that is linked to the accelerator pedal in the driver's cab, a surge tank 4, and an intake pipe 5. The intake pipe 5 is connected to the engine. It is connected to the main body 6. A combustion chamber 7 of the engine body 6 is divided by a cylinder head 8, a cylinder block 9, and a piston 10, and the air-fuel mixture is supplied to the combustion chamber 7 through an intake valve 14 to be combusted, and is then combusted through an exhaust valve 15. It is discharged from chamber 7. The exhaust system includes exhaust branch pipes 18 in order from the upstream.
A catalytic converter 19 housing a three-way catalyst that promotes the oxidation and reduction of harmful components in the exhaust gas, and an exhaust pipe 20 are provided. 1st and 2nd
The bypass passages 23 and 24 connect the portion of the intake passage 25 upstream of the throttle valve 3 and the surge tank 4, and the first and second bypass passages 23 and 24 are provided with an electromagnetic on-off valve 26 and a bimetallic on-off valve, respectively. 27 are provided. Note that there is also a model that controls the air bypass flow rate during the entire idle period using only the first bypass passage 23; in this case, the second
The first bypass passage 24 is not provided, and the flow cross-sectional area of the first bypass passage 23 is maintained at a large value when the engine is at a low temperature. First bypass passage 2
3 is provided to stabilize the rotation of the engine during idling, and the electromagnetic on-off valve 26 is connected to the first bypass passage 23 in relation to the idling rotational speed.
Open and close. The second bypass passage 24 is provided to improve engine operation during warm-up, and the bimetallic on-off valve 27 opens the second bypass passage 24 when the engine temperature is below a predetermined temperature.
The fuel injection valve 28 is attached to the intake pipe 5 toward the combustion chamber 7, and opens and closes in response to an electrical input signal to inject fuel. The air-fuel ratio sensor 29 is attached to the exhaust branch pipe 18 and detects the oxygen concentration in the exhaust gas. The crank angle sensor consists of two parts 30 and 31, and detects the crank angle from the rotation of the shaft of a power distributor 32 coupled to the crankshaft. One part 30 generates one pulse for every 720° change in crank angle, and the other part 30
generates one pulse for every 30° change in crank angle. The power distributor 32 receives a secondary current from the ignition coil 33 and distributes this secondary current to the spark plugs of each combustion chamber. The throttle sensor 34 detects the opening degree of the throttle valve 3. The vehicle speed sensor 35 detects the rotation of the output shaft of the automatic transmission 36, that is, the vehicle speed. A water temperature sensor 37 is attached to the cylinder block 9 to detect the temperature of the cooling water. Electronic control device 4
1 is an air flow meter 2, an air-fuel ratio sensor 29, a crank angle sensor portion 30, 31, and an ignition coil 3.
3 (ignition confirmation signal), throttle sensor 34, vehicle speed sensor 35, and water temperature sensor 37, electromagnetic control valve 26, fuel injection valve 28, ignition coil 33 (primary current), and automatic transmission 3
An output signal is sent to the solenoid 42 of the hydraulic control circuit 6. The electronic control unit 41 includes a CPU (central processing unit), a ROM (read-only storage device), and a RAM (direct access storage device) consisting of a microcomputer.
The CPU calculates the fuel injection amount, fuel injection timing, and ignition timing according to a predetermined program in the ROM.

FIG. 2 is a skeleton diagram of the automatic transmission 36. The hydraulic torque converter 45 includes a pump impeller 46 , a stator 48 fixed via a one-way clutch 47 , and a turbine runner 49 , a crankshaft 53 is connected to the pump impeller 46 , and an input shaft 51 of an underdrive device 50 . is connected to the turbine runner 49. A direct coupling clutch 52 is provided in parallel to the hydraulic torque converter 45 and connects the crankshaft 50 and the input shaft 51. The overdrive device 55 includes a sun gear 56, a carrier 57, a planetary pinion 58,
and a ring gear 59, the carrier 57 is connected to the output shaft 60 of the underdrive device 50, the ring gear 59 is fixed to the output gear 61, the sun gear 56 and the ring gear 59
A one-way clutch 62 and a clutch 6 are connected between the
3, and a brake 65 is provided between the sun gear 56 and the housing 64. During underdrive, the one-way clutch 62 or clutch 63 (especially during engine braking during underdrive) is engaged, and the reduction ratio of the overdrive device 55 becomes 1. During overdrive (at the highest speed), the clutch 63 is engaged, and the reduction ratio of the overdrive device 55 becomes 1. 65 becomes engaged, and the reduction ratio of the overdrive device 55 becomes smaller than 1 (speed increase).

3-5 illustrate a flowchart of a program implementing the method of the invention. The program shown in FIG. 3 is executed when the driver turns on the ignition switch in the cab, that is, when the engine starts operating. In step 70, overdrive and lockup are prohibited. Note that "lockup" means that the direct coupling clutch 52 is engaged and engine power is transmitted from the crankshaft 53 to the input shaft 51 without going through the hydraulic torque converter 45. When overdrive and lockup are inhibited, predetermined solenoids of the hydraulic control device of the automatic transmission 36 are maintained in an energized or deenergized state, thereby stopping the supply of hydraulic pressure to the hydraulic servo of the direct coupling clutch 52 and the brake 65. , Clutch 6
The supply of hydraulic pressure to the hydraulic servo No. 3 is maintained. In step 71, the counter is cleared.

The program shown in FIG. 4 is executed every time the crankshaft rotates once during engine operation. In step 75, it is determined whether the fuel injection amount has been increased by the amount increased after starting. If the determination result is positive, the process proceeds to step 76, and if not, the process proceeds to step 80. For a predetermined period of time after starting, the fuel injection amount is increased by a predetermined amount in order to avoid engine rotation stoppage (engine stall). In step 76, it is determined whether the cooling water temperature is 70°C or higher, that is, whether it is being warmed up or after warming up, and if it is warming up, it proceeds to step 77, and if it has finished warming up, it proceeds to step 79. . In step 77, 1 is added to the counter. In step 78, it is determined whether the content of the counter is greater than or equal to a predetermined value A, that is, it is determined whether the total number of revolutions of the engine has reached a predetermined value or more since the start of the engine, and if the determination result is positive, then Proceed to step 79, and if not, end this program. A is, for example, 4096, which is the value at which the 3-digit hexadecimal counter overflows. The stability of engine operation is more closely related to the total number of revolutions of the engine from the start of the engine than to the engine temperature.If the engine speed is 1000rpm (revolutions per minute), the 4096 will be approximately 4 Corresponds to the total number of revolutions of the engine in minutes. At step 79, overdrive and lockup are permitted. Therefore, overdrive and lockup are performed in a predetermined region determined by the relationship between the opening degree of the throttle valve 3 and the vehicle speed. In step 80, the counter is cleared. Therefore, the counter increases by 1 for each revolution of the crankshaft after the fuel injection amount has finished increasing after starting.
are added in increments. In step 81, overdrive and lockup are prohibited.

The program shown in FIG. 5 is executed every time a predetermined number of pulses are input from the vehicle speed sensor 35. Vehicle speed sensor 35 generates pulses in relation to the rotation of automatic transmission 36. At step 85, the vehicle speed is 80km/h.
It is determined whether the above is the case, and if the determination result is positive, the process proceeds to step 86, and if not, the program is terminated. In step 86, a predetermined value b greater than 1 is added to the counter. For example, b is 40.
In step 87, it is determined whether the content of the counter is greater than or equal to A. If the determination result is positive, the program proceeds to step 88, and if not, the program is terminated. Step 88 allows overdrive and lockup. Therefore, the vehicle speed is 80km/h
After reaching this point, overdrive and lockup are permitted early regardless of whether or not the engine is being warmed up. When driving at high speeds, the engine is operating with sufficient output, so there is no risk of deterioration in driving performance even during warm-up, and overdrive and lock-up are implemented to suppress fuel consumption during high-speed driving. Ru.

According to this embodiment, engagement of the direct coupling clutch and overdrive are prohibited when the engine temperature is below a predetermined temperature, the vehicle speed is below a predetermined value, and the total number of rotations of the engine from the start of the engine is below a predetermined value. is,
As a result, the reduction ratio of the automatic transmission is maintained at a large value, so engine operation becomes stable and good acceleration is ensured. Furthermore, the reduction ratio of the automatic transmission is maintained at a large value, reducing the load on the engine, thereby reducing fuel consumption and preventing overheating of the catalytic converter. Furthermore, even during warm-up, when the total engine speed exceeds a predetermined value or when running at high speed, the engine operation is sufficiently stable, so engagement of the direct coupling clutch and overdrive are permitted. Fuel consumption is reduced.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an electronically controlled engine to which the present invention is applied, Fig. 2 is a partially omitted skeleton diagram of an automatic transmission, and Fig. 3 is a schematic diagram of an electronically controlled engine to which the present invention is applied. FIG. 4 is a flowchart of a program executed for each rotation of the engine according to an embodiment of the present invention, and FIG. This is a flowchart of related programs executed. 30... One part of the crank angle sensor, 35
...Vehicle speed sensor, 36...Automatic transmission, 37...
Water temperature sensor, 41... Electronic control device, 42... Solenoid, 45... Fluid torque converter, 5
2... Direct connection clutch, 55... Overdrive device.

Claims (1)

[Scope of Claims] 1. In an automatic transmission that includes a direct coupling clutch provided in parallel to a hydraulic torque converter and transmits engine power to drive wheels at a plurality of reduction ratios, The engine is characterized by detecting the number of revolutions and, if the total number of revolutions is less than a predetermined value, executing warm-up stabilization control that prohibits engagement of the direct coupling clutch or shifting to the highest gear. , automatic transmission control method.