JPH11182277A - Idling rotation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase correction of intake air in idling control due to wrong detection of oil pressure rise caused by driving a hydraulic pump for a power steering when cooling water temperature at the time of start-up is low. SOLUTION: In an idling rotation control method for controlling idling speed to be the preset target idling speed by controlling the intake air quantity at the time of idling operation of an internal combustion engine with a hydraulic pump of a power steering controlled by hydraulic control mechanism including the hydraulic pump, as load, the temperature of the internal combustion engine at the time of start-up is detected, and judgment time is set shorter as the detected temperature becomes higher. In the case of the elapsed time from start-up being less than the set judgment time, the increase correction of the intake air quantity corresponding to load is forbidden until the judgment time elapses.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle rotation control method for an internal combustion engine having at least a load of a hydraulically controlled power steering.

[0002]

2. Description of the Related Art Conventionally, in order to facilitate the operation of turning a steering wheel, a hydraulic pump is driven by an engine, and a power for assisting a force for operating the steering wheel by a hydraulic pressure generated by the hydraulic pump. Vehicles equipped with steering are known. In an engine mounted on such a vehicle, for example, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-147037, a hydraulic pump becomes a load on the engine during idling operation, and the idling engine speed temporarily drops from a target speed. In order to prevent this, the power steering oil pressure is detected to detect that the operation of the power steering has become a load on the engine, the correction amount of the intake air is determined according to the load, and the idle speed is set to the target. The control is performed so as to converge on the rotation speed.

A power steering device that assists the operation of a steering wheel using such a hydraulic pressure includes a hydraulic pump for supplying hydraulic oil from an oil tank, a control valve for controlling the hydraulic pressure by operating the steering wheel, Generally, a power cylinder for steering wheels by hydraulic pressure from a control valve and a hydraulic switch for detecting the operation of a hydraulic pump as an engine load by hydraulic pressure are provided.

[0004]

By the way, in the above configuration, at low temperature, the viscosity of the hydraulic oil of the hydraulic pump increases for a few seconds after the engine is started even though the hydraulic pump is not rotating. However, the hydraulic switch may be turned on. This is because the hydraulic switch is provided in the hydraulic path between the hydraulic pump and the control valve, and when the viscosity increases in the hydraulic path, the hydraulic switch responds to the change in the viscosity.

As described above, when the hydraulic switch is turned on,
The control device that controls the rotation of the engine determines that the hydraulic pump has been activated, and performs a correction according to the load in the same way as when the load is applied to the engine even though the hydraulic pump is not driven. is there. For this reason, when the load is not actually applied to the engine and the intake air amount is corrected under the load, the idle engine speed increases and the convergence to the target speed decreases. there were.

An object of the present invention is to solve such a problem.

[0007]

In order to achieve the above object, the present invention takes the following measures. That is, the idle rotation control method according to the present invention includes:
When the power steering of the hydraulic control system becomes a load on the internal combustion engine, if the determination time is in accordance with the temperature of the internal combustion engine, the increase correction of the intake air amount according to the load is prohibited. is there.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention controls the amount of intake air during idle operation of an internal combustion engine having at least the load of a power steering hydraulic pump controlled by a hydraulic control mechanism including a hydraulic pump to reduce the idle speed. An idle rotation control method for controlling to a set target rotation speed, wherein the temperature of the internal combustion engine at the time of starting is detected,
The determination time is set shorter as the detected temperature increases, and when the elapsed time from the start is shorter than the set determination time, the increase correction of the intake air amount according to the load is performed by the determination time. This is an idle rotation control method characterized by prohibiting until the elapse.

With this configuration, it is possible to prohibit the increase correction of the intake air amount when the power steering is loaded for a predetermined time after the start according to the temperature of the internal combustion engine at the start. Become. In this case, at the time of starting, the temperature of the internal combustion engine is low and the viscosity of the hydraulic oil delivered from the hydraulic pump of the hydraulic control mechanism is high, so that the operation of the hydraulic pump is erroneously detected as the load on the internal combustion engine. However, since the temperature of the internal combustion engine is low, the determination time is set to be long, and increase correction of the intake air amount is prohibited until the determination time has elapsed. As a result, abnormal increase of the idle speed due to improper increase of the intake air amount is suppressed until the determination time elapses from the start. Therefore, the idle operation state can be stabilized immediately after the start, and the idle speed can converge to the target speed.

[0010] The temperature of the internal combustion engine includes a cooling water temperature, a lubricating oil temperature, an intake air temperature and the like.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. The engine 100 shown in FIG. 1 is for a water-cooled automobile, and the automobile is equipped with a power steering PS. The power steering PS can control the steering force for steering by a hydraulic control mechanism PSM including a hydraulic pump PS3. Hydraulic control mechanism PS
M is set so that, for example, when the rotation speed of the engine 100 is low, the operation force for turning the steering wheel SWH is small, and when the rotation speed is high, a large operation force is required to turn the steering wheel SWH. I have.

The hydraulic control mechanism PSM includes an oil tank PS
1. A hydraulic pump P that sends out the hydraulic oil in 1 to a hydraulic path PS2
S3, a hydraulic pump main body PSp including a flow control valve PS4 for controlling hydraulic oil sent from the hydraulic pump PS3 and a relief valve PS5 for returning hydraulic oil to the oil tank PS1, and an operation sent from the hydraulic pump main body PSp. A power steering system comprising: a control valve PS7 for controlling oil in accordance with a rotation angle of a steering wheel SWH via a steering gear PS6; and a power cylinder PS8 for controlling a steering angle of wheels T by hydraulic oil flowing in via the control valve PS7. The apparatus includes a main body PSb, and a hydraulic switch PS9 attached to a hydraulic path PS2 between the hydraulic pump main body PSp and the power steering main body PSb to detect a hydraulic pressure of hydraulic oil. The hydraulic switch PS9 is turned on when the oil pressure of the hydraulic oil becomes equal to or higher than a predetermined pressure. When the oil pressure decreases, the oil pressure switch PS9 becomes equal to or lower than a second predetermined pressure set to a pressure lower than the predetermined pressure. Is set to turn off when
A power steering signal PST as an output signal is input to an electronic control device 4 described later. The hydraulic control mechanism P
SM may apply what is well known in this field. Further, the hydraulic control mechanism may be controlled according to the vehicle speed.

An intake system 11 of the engine 100 shown schematically in FIG. 2 is provided with a throttle valve 12 that opens and closes in response to an accelerator pedal (not shown), and a bypass passage 13 that bypasses the throttle valve 12. A flow control valve 14 for controlling the idle speed is provided in the bypass passage 13. This flow control valve 14
An electronic opening and closing type, which is abbreviated as a large flow rate VSV,
The duty ratio of the drive voltage, which is a control value applied to the terminal 14a, is controlled by a calculated duty ratio DISC calculated based on various correction amounts. By performing such control, the opening degree per unit time can be changed, whereby the air flow rate of the bypass passage 13 can be adjusted, and the engine speed NE can be maintained at the target speed. I have.

The calculated duty ratio DISC therefore indicates the corrected amount of intake air during idling operation. Thus, the bypass passage 13 and the flow control valve 1
By means of a set of 4, the bypass path normally provided for each correction item in the feedback control during the idling operation is unified. In addition, the calculation duty ratio DISC includes those items and, for example, the respective correction items such as the start-time correction amount DSTA, the water temperature correction amount DAAV, the feedback correction amount DFB, and the load correction amount DSET are extremely large. Alternatively, the variable range is limited so as not to be small. The calculation duty ratio DISC is calculated by the following equation.

DISC (%) = DSTA + DAAV +
The DFB + DSET intake system 11 is further provided with a fuel injection valve 15.
The fuel injection valve 15 and the flow control valve 14 are controlled by the electronic control unit 4. Electronic control unit 4
Is mainly composed of a microcomputer system including a central processing unit 4a, a storage device 4b, an input interface 4c, and an output interface 4d. And the input interface 4c
Includes an intake pressure signal a output from an intake pressure sensor 17 for detecting a pressure PM (intake pipe pressure) in a surge tank 16, and a rotational speed output from a rotational speed sensor 18 for detecting an engine rotational speed NE. A signal b, a vehicle speed signal c output from a vehicle speed sensor 19 for detecting the vehicle speed, an IDL signal d from an idle switch 20 for detecting the open / closed state of the throttle valve 12, and a sensor for detecting a cooling water temperature of the engine 100. A water temperature signal e from the water temperature sensor 21,
Reference position signal f output from crank angle reference position sensor 23 built in distributor 22, exhaust system 2
An output signal h that changes in accordance with the air-fuel ratio from the O ₂ sensor 25 provided in the apparatus 4 and a power steering signal PST output from the hydraulic switch PS9 are input.

The electronic control unit 4 detects the current operating state based on signals from the respective sensors,
Based on the detection result, the fuel injection valve opening time is determined by using the signal from the intake pressure sensor 17 and the signal from the rotation speed sensor 18 as main information, and the fuel injection valve 15 is controlled based on the determination, and the fuel injection valve 15 is controlled according to the operating state. A program for injecting fuel from the fuel injection valve 15 to the intake system 11 is incorporated. In the electronic control unit 4, the cooling water temperature, which is the temperature of the engine 100 at the time of starting, is detected, and the determination time is set to be short as the detected cooling water temperature increases, and the elapsed time from the start is set. If the time is shorter than the determination time, a program having a configuration for prohibiting the increase correction of the intake air amount according to the load is incorporated.

The outline of the idle speed control (ISC) program is as shown in FIG. When executing this program at regular intervals or at constant crank rotations, it goes without saying that it is detected that the idling operation condition is satisfied. Idle operating conditions are:
For example, the setting is made based on that the throttle valve 12 is closed, the vehicle speed is equal to or lower than a predetermined speed, and the like.

In the idle rotation control, the above-described determination time, that is, the power steering signal cancel time PSTCEL is set with respect to the cooling water temperature by using a map.
Power steering signal cancel time PSTCEL
Is the cooling water temperature, that is, the starting water temperature TH, as shown in FIG.
It is set so that it becomes longer as the WIG becomes lower, and becomes shorter as the starting water temperature THWIG becomes higher. A map for setting the power steering signal cancellation time PSTCEL is stored in the storage device 4b.

First, in step S1, a map is searched based on the detected starting water temperature THWIG, and a corresponding power steering signal cancel time PSTCEL is set. In step S2, it is determined whether or not the elapsed time from the start, that is, the elapsed time after the start has exceeded the set power steering signal cancel time PSTCEL.
If it exceeds, the process proceeds to step S3, and in the following cases, the process proceeds to step S4. When the starting water temperature THWIG is low and it is determined in step S2 that the post-start elapsed time is equal to or less than the power steering signal cancel time PSTCEL, the power steering correction flag PSTFLG is reset (= 0) in step S4. This power steering correction flag PSTFLG indicates the load correction amount D
This is for determining whether or not to set the SET. If the SET has been reset, the load correction amount DSET is not set. On the other hand, if it is determined in step S2 that the post-start elapsed time has exceeded the power steering signal cancel time PSTCEL, the process proceeds to step S3, in which it is determined whether the hydraulic switch PS9 is on (PST = 0). ,
If it is on, the process proceeds to step S5, and if it is off, the process proceeds to step S4.

When the hydraulic switch PS9 is on, a load correction amount DSET is set, and a calculation duty ratio DISC is calculated. As a result, the load correction amount DSET
, The intake air amount is increased and corrected. On the other hand, if the hydraulic switch PS9 is off, the process proceeds to step S4, and the power steering correction flag PSTFLG is reset. When the hydraulic switch PS9 is on,
In step S5, a power steering correction flag PSTFLG is set (= 1). Therefore, when this program is executed next, if the elapsed time after starting exceeds the power steering signal cancel time, the control proceeds to steps S1, S2, S3, and S5, and
The load correction amount DSET is set according to the load state at that time, and the increase in the intake air amount is corrected.

Therefore, when the starting water temperature THWIG is low, the power steering signal cancel time PS
The TCEL is set long, and the correction of the increase in the calculation duty ratio DISC by the load correction amount DSET is not performed until the elapsed time after the start exceeds the power steering signal cancellation time PSTCEL. That is, the starting water temperature THWI
Since G is low, the viscosity of the hydraulic oil of the hydraulic control mechanism PSM becomes high, and even if the hydraulic switch PS9 is turned on when the hydraulic pump PS3 is not driven, even during the set power steering signal cancel time PSTCEL, Until that time has elapsed, as shown in FIG. 5, the power steering signal PST output from the hydraulic switch PS9
Is ignored, so that the load correction amount DSET is not set corresponding to the power steering signal PST. Also, the power steering signal cancel time PSTCE
When L does not elapse, even if the hydraulic pump PS3 is driven and the hydraulic switch PS9 is actually turned on, if the elapsed time after the start does not exceed the power steering signal cancel time PSTCEL at that time, the control proceeds to step S
The process proceeds from 1 to S2 to S3 to S4, and the calculation duty ratio DISC is not corrected by the load correction amount DSET, so that the increase correction of the intake air amount is not performed.

As a result, even if the hydraulic switch PS9 is turned on due to the high viscosity of the hydraulic oil, the increase in the intake air amount based on the load correction amount DSET set due to malfunction does not occur. Therefore, the idle speed does not significantly exceed the target speed, and the stability of the idle speed after starting can be improved. In addition, the convergence of the subsequent idle rotation to the target rotation speed can be improved.

In contrast to the above, when the cooling water temperature is high at the time of restarting after warm-up or the like, the power steering signal canceling time P set based on the starting water temperature THWIG is set.
Since the STCEL is set short, even if the power steering PS is operated and the hydraulic pump PS3 is driven during that time, the increase correction by the appropriate load correction amount DSET is performed within a short time. That is, control is performed in step S
In a state in which the elapsed time after starting does not exceed the power steering signal cancel time PSTCEL, the power steering correction flag PSTFLG proceeds from 1 → S2 → S4.
Is reset, the increase correction based on the load correction amount DSET is not performed. Thereafter, since the hydraulic pump PS3 has already been driven, the control is performed in steps S1 → S2 → S3 →
Proceeding to S5, the power steering correction flag PSTFL
G is set, and the increase correction by the load correction amount DSET is performed. Therefore, when the hydraulic pump PS3 is actually being driven, an appropriate correction of the intake air amount is performed, so that it is possible to converge on the target rotational speed without lowering the idle rotational speed.

The present invention is not limited to the embodiment described above. In addition, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0025]

As described above, according to the present invention, according to the temperature of the internal combustion engine at the time of starting, the intake air amount when the power steering is used as a load until a predetermined time after starting has elapsed. During this period, the idle rotation speed can be prevented from abnormally increasing due to inappropriate intake air amount increase correction. Therefore, the idle operation state can be stabilized immediately after the start, and the idle speed can converge to the target speed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a hydraulic control mechanism according to an embodiment of the present invention.

FIG. 2 is a schematic configuration explanatory view showing an engine and an electronic control unit of the embodiment.

FIG. 3 is a flowchart showing a control procedure of the embodiment.

FIG. 4 is a graph showing a relationship between a power steering signal cancellation time and a starting water temperature according to the embodiment.

FIG. 5 is an operation explanatory view of the embodiment.

[Explanation of symbols]

 PSM ... Hydraulic control mechanism PS3 ... Hydraulic pump PS ... Power steering 4 ... Electronic control device 4a ... Central processing unit 4b ... Storage device 4c ... Input interface 4d ... Output interface 21 ... Water temperature sensor

Claims (1)

[Claims] An idle speed is controlled by controlling an intake air flow rate during idle operation of an internal combustion engine having at least a load of a power steering hydraulic pump controlled by a hydraulic control mechanism including a hydraulic pump. An idle rotation control method that detects the temperature of the internal combustion engine at the time of starting, sets a short judgment time as the detected temperature increases, and sets the elapsed time from the start. An idle rotation control method, wherein when the determination time is shorter than a predetermined time, increase correction of the intake air amount according to the load is prohibited until the determination time elapses.