JPH05280399A - Idle speed control device for engine - Google Patents

Abstract

PURPOSE:To improve a fuel consumption ratio when a shift range is at a run range by setting an idle rotation speed of an engine higher when an oil temperature of an automatic transmission is high than that when the oil temperature is normal so as to set the idle rotation speed to be properly lower. CONSTITUTION:An idle rotation speed control device for an engine is applied to a vehicle mounting an automatic transmission. In this case, if a shift range is at a run range or not is determined by a determination means. In the meanwhile, an oil temperature of an automatic transmission is detected by an A/T oil temperature sensor. When it is determined that the shift range is at the run range, if the oil temperature of the automatic transmission is high, the idle rotation speed of the engine is set higher than that when the oil temperature is normal by the idle rotation speed control means. The idle rotation speed for a D-range can thus be restricted to be properly lower, thereby a fuel consumption ratio can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an engine, which is particularly applied to a vehicle equipped with an automatic transmission having a lockup clutch.

[0002]

2. Description of the Related Art Conventionally, in an electronically controlled engine, the idle speed of the engine is set to the on / off state of an air conditioner.
Usage of various electric loads, shift range of automatic transmission,
It is designed to be changed and set depending on the engine cooling water temperature. For example, when the air conditioner is on, or when the electric load is large, the idle speed is set to a higher value, and when the shift range is a drive range such as a drive range, it is usually more than when it is a non-drive range such as a neutral range. The idle speed is set to be low.

Further, in Japanese Patent Laid-Open No. 3-115755, in relation to the warm-up and the oil temperature of the automatic transmission, even if the warm-up is completed, if the oil temperature is extremely low, a technique for increasing the idle rotation speed. Is proposed.

[0004]

By the way, such conventional control of the idle rotation speed is not always sufficient control from the viewpoint of the automatic transmission, particularly in terms of improvement of fuel consumption. There was a face. Hereinafter, that point will be described.

In the automatic transmission, the hydraulic pressure generated by the rotation of the pump is used to operate various elements (clutch, brake, etc.) to control the shift. Therefore, it is necessary to secure the discharge capacity of this pump in a necessary and sufficient manner. The magnitude of this discharge capacity depends on the rotational speed of the pump. Therefore, the rotation speed of the engine is set so as to ensure the required discharge capacity. For example, when traveling in the D range, when the vehicle speed decelerates below a predetermined speed or stops, the lockup clutch is disengaged to put the engine in an idle state, and stable operation performance is secured at this time. Thus, the idle rotation speed in the D range is set.

Normally, this idle rotation speed is set with a slight margin at room temperature. This is because the amount of oil leakage in the automatic transmission control unit (so-called valve body) changes depending on the oil temperature in the oil pan and tends to increase at high oil temperatures. That is, when the oil temperature becomes extremely high after high-load operation on a mountain road or the like, the amount of leakage increases and the pump discharge amount becomes insufficient, and as a result, various controls of the automatic transmission are hindered. It may occur. Therefore, in order to allow the automatic transmission to function without problems even in such a high oil temperature state, the idle setting is set with a slight margin in the normal temperature state.

In other words, at present, the special condition, that is, the idle rotation speed in the D range is set to a high value on the basis of the time of high oil temperature, so that the capacity is excessive at room temperature and the fuel consumption is sacrificed accordingly. It means that it is set to.

The present invention has been made in view of such conventional problems, and it is an object of the present invention to improve the fuel consumption by suppressing the idle rotation speed of the D range to be appropriately low.

[0009]

As shown in FIG. 1, the present invention provides an engine idle speed control device applied to a vehicle equipped with an automatic transmission, in which the shift range of the automatic transmission is When it is determined that the shift range is in the running range and the shift range is determined to be the running range, the determination means that determines whether the running range is the running temperature, the normal temperature when the oil temperature of the automatic transmission is high And a means for setting the idle rotation speed of the engine higher than that in the above case.

[0010]

In the present invention, when it is determined that the shift range is the running range, the idle rotation speed is changed / set according to the oil temperature of the automatic transmission, and when the oil temperature of the automatic transmission is high, the engine speed of the engine is increased. When the idle speed is high and the oil temperature is room temperature, the engine idle speed is set low.

As a result, the capacity of the oil pump can be sufficiently ensured even under traveling under special conditions, for example, the release performance of the lock-up clutch can be reliably ensured, and the idle speed can be lowered as much as possible. It is possible,
It becomes possible to improve fuel efficiency.

[0012]

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

FIG. 2 is an overall schematic diagram of an engine with an automatic transmission to which the present invention is applied. This engine is an intake air amount sensing type electronic fuel injection engine for automobiles, and its output shaft is connected with an automatic transmission (hereinafter referred to as ECT) 900 shown in FIG.

The air sucked from the air cleaner 10 is
The air flow meter 12, the intake throttle valve 14, the surge tank 16, and the intake manifold 18 are sequentially sent. This air is mixed with fuel injected from the injector 22 in the vicinity of the intake port 20 and is further sent to the combustion chamber 26A of the engine body 26 via the intake valve 24. Combustion chamber 26
Exhaust gas generated as a result of combustion of the air-fuel mixture in A is an exhaust valve 28, an exhaust port 30, an exhaust manifold 32.
And to the atmosphere via an exhaust pipe (not shown).

The air flow meter 12 is provided with an intake air temperature 100 sensor for detecting the intake air temperature.
Further, the exhaust manifold 32 is provided with an exhaust temperature sensor 101 for detecting the exhaust temperature of the engine.
The intake throttle valve 14 rotates in conjunction with an accelerator pedal (not shown) provided in the driver's seat. The intake throttle valve 14 is provided with a throttle sensor 102 for detecting its opening.

A water temperature sensor 104 for detecting the engine cooling water temperature is provided on the cylinder block 26B of the engine body 26. Further, the distributor 38 having a shaft rotated by the crank shaft of the engine body 26 is provided with a crank angle sensor 108 for detecting a crank angle from the rotation of the shaft, from which the engine rotation speed is detected. It has become so.

Further, the ECT has a rotation speed N of its output shaft.
A vehicle speed sensor 110 for detecting the vehicle speed from 0, a C0 sensor 113 for detecting the rotational speed of the clutch C0, and a shift position sensor 1 for detecting the shift position.
12. Further, a sensor 111 for detecting the oil temperature in the oil pan of the automatic transmission is provided.

Each of these sensors 100, 101, 10
2, 104, 108, 110, 111, 112, 11
3 and the outputs of the pattern select switch 114, the overdrive switch 116, and the brake lamp switch 118 are the engine computer 40 or the ECT.
It is input to the computer 50.

The engine computer 40 calculates the fuel injection amount and the optimum ignition timing by using the input signals from the respective sensors as parameters, and controls the injector 22 so that the fuel is injected for a predetermined time corresponding to the fuel injection amount. The ignition coil 44 is controlled so that the optimum ignition timing is obtained.

An idle speed control valve (ISCV) 4 driven by a step motor is provided in a bypass passage for connecting the upstream side of the intake throttle valve 14 and the surge tank 16.
Two are provided.

The engine computer 40 uses the E
By receiving the oil temperature information of the automatic transmission from the CT computer 50 and controlling the idle rotation speed control valve 42, the idle rotation speed of the engine is controlled in consideration of the oil temperature of the automatic transmission in addition to the conventional parameters. To do.

This specific control flow will be described later in detail.

On the other hand, the transmission section 900 of the ECT in this embodiment comprises a torque converter 910, an overdrive mechanism 920, and an underdrive mechanism 930, as shown in FIG. The torque converter 910 is a known one including a pump 911, a turbine 912, and a stator 913, and includes a lockup clutch 914.

The overdrive mechanism 920 includes a sun gear 921, a planetary pinion 922 that meshes with the sun gear 921, a carrier 923 that supports the planetary pinion 922, and a ring gear 924 that meshes with the planetary pinion 922. Equipped with
The rotation state of this planetary gear device is controlled by the clutch C0, the brake B0, and the one-way clutch F0.

The underdrive mechanism 930 includes a common sun gear 931, planetary pinions 932 and 933 meshing with the sun gear 931, and the planetary pinion 9.
Carriers 934 and 935 supporting 32 and 933, and a ring gear 9 that meshes with planetary pinion 932 and 933.
Two sets of planetary gear units 36 and 937 are provided, and the rotation state of the planetary gear unit and the connection state with the overdrive mechanism are clutches C1 and C2 and brakes B1 to B1.
It is controlled by B3 and one-way clutches F1, F2. Since the transmission unit 900 is known per se, the connection state of each component will be described with reference to FIG.
In the figure, only the skeleton is shown and the detailed description is omitted.

The ECT in this embodiment includes the transmission section 900 as described above, the throttle sensor 102, the vehicle speed sensor 110, or the C0 sensor 1.
The electromagnetic valves S1 to S4 in the hydraulic control circuit 60 are driven and controlled by the ECT computer 50 to which signals such as 13 are input according to a preset shift pattern, and each clutch, brake, etc. as shown in FIG. The gear shift control is performed by combining the engagements. In FIG. 4, the mark ◯ indicates the operating state, and the mark ⊚ indicates the operating state only during driving.

Next, a specific control flow of the idle speed will be described with reference to FIG.

In this embodiment, in the D range, the target value of the idle speed is determined depending on the oil temperature of the automatic transmission when a predetermined condition is satisfied. Further, the on / off of the air conditioner, the types of shift ranges such as N, P, and D of the automatic transmission, and the electric load are also determinants of the idle rotation speed, but these points are different from the conventional ones. Since it is not available, it is omitted for simplicity.

Similarly, although the engine cooling water temperature is also an important determinant factor of the idle speed, the engine cooling water temperature rises faster than the oil temperature of an automatic transmission, and therefore the engine speed of the automatic transmission is increased based on the present invention. When the oil temperature rises to a level at which the target value of the idle rotation speed is switched, the engine cooling water temperature has already risen to a certain value or higher, so it is omitted here.

A detailed description will be given.

The flow of FIG. 5 is for the case where the shift range is the D range, and is executed only when the D range is selected.

When this flow starts, first, in step 202, the vehicle speed v is measured. Next, in step 204, it is determined whether the vehicle is stopped. If the vehicle is not stopped, it is further determined in step 206 whether the vehicle speed v is less than or equal to the preset vehicle speed V. If the vehicle speed v is less than or equal to the set vehicle speed V, in step 208 the current vehicle speed and the previous vehicle speed are determined. Compare with. And step 21
At 0, it is determined whether or not the result of comparison is deceleration.

If the vehicle speed v is less than or equal to the set vehicle speed V and is decelerating, or if the vehicle is stopped, step 21
Go to 2. When such a condition is established, the lockup clutch 914 is controlled to be released.

On the other hand, if the vehicle speed v is not equal to or lower than the set vehicle speed V, or if the vehicle speed is equal to or lower than the set vehicle speed V but is not decelerating, the routine returns from step 206 or 210 to step 202.

When the process proceeds to step 212, the oil temperature of the automatic transmission (A / T) is measured here, and then step 2
Proceeding to 14, the idle target rotation speed Ne of the D range is calculated from the measured oil temperature and a map defining the relationship between the oil temperature and the idle rotation speed Ne.

The map in this case defines the relationship that the higher the A / T oil temperature, the higher the idle rotation speed Ne, and the lower the idle rotation speed Ne when the oil temperature is at the room temperature level.

The relationship between the oil temperature and the idle target rotation speed Ne may be set to change continuously as in the present embodiment, or the idle target rotation speed may be set to change in at least two stages. Good.

In the engine control computer 40, the idle rotation speed control valve 42 is feedback-controlled from the actual value of the engine rotation speed obtained from the target value Ne of the idle rotation speed and the detected value of the crank angle sensor 108, and the actual control is performed. The idle rotation speed of is matched with this target value.

In this embodiment, since the idle speed of the engine becomes high even when the oil leakage is high and the oil temperature is high, such as after special running, the line pressure does not drop. Thus, the lock-up clutch releasing operation is smoothly performed. On the other hand, since the idle rotation speed becomes low at room temperature when the amount of oil leakage is small, the fuel efficiency is improved correspondingly during most traveling.

In the above embodiment, the oil temperature in the oil pan is typically used as the oil temperature of the automatic transmission. However, if it is difficult to detect the oil temperature in the oil pan, this is used. What can be estimated, for example, the oil temperature of the portion entering the cooler may be representative of the oil temperature of the automatic transmission.

[0041]

As described above, according to the present invention, the idle speed is changed in accordance with the oil temperature of the automatic transmission, so that the vehicle is traveling at room temperature with a small amount of oil leakage, that is, most of the traveling. It is possible to suppress the idle rotation speed in the state of occupying the vehicle to a lower value than in the conventional case, and it is possible to improve fuel efficiency accordingly.

Further, even if the oil temperature becomes abnormally high after a special running such as running in a mountainous area, resulting in a large oil leak amount, a sufficient oil flow rate can be secured. Even if the lockup clutch is released under the condition, no trouble occurs.

[Brief description of drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is an overall schematic diagram of an electronic fuel injection engine for an automobile to which the present invention is applied.

FIG. 3 is a schematic diagram of the automatic transmission shown in FIG.

FIG. 4 is a diagram showing an operating state of each friction engagement device of the automatic transmission.

FIG. 5: Engine control computer or E
Flow chart of control executed by CT computer

[Explanation of symbols]

26 ... Engine main body, 108 ... Crank angle sensor (engine rotation speed sensor), 110 ... Vehicle speed sensor, 111 ... Automatic transmission oil temperature sensor, 112 ... Shift position sensor, 900 ... Automatic transmission, 42 ... Idle rotation speed control Valve, 40 ... Engine computer, 50 ... ECT computer.

Claims (1)

[Claims] Claim: What is claimed is: 1. In an engine idle speed control device applied to a vehicle equipped with an automatic transmission, a determination means for determining whether or not a shift range of the automatic transmission is a traveling range, and an oil for the automatic transmission. A means for detecting the temperature and a means for setting the idle speed of the engine to be higher when the oil temperature of the automatic transmission is higher than that at the normal temperature when it is determined that the shift range is the traveling range. An idle speed control device for an engine, which is characterized by being provided.