JPH0226697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine idle rotation control device, and more particularly to an idle rotation control device that allows an engine to idle at the most preferable rotation speed depending on engine load conditions.

Generally, in an automobile engine, the engine rotational speed when the vehicle is stopped, that is, when the engine is in an idling state, is kept as low as possible within the limit that allows a stable operating state to be obtained. However, if this engine speed is set under normal operating conditions, if the engine is at a low temperature such as during a cold start, the atomization or vaporization of the air-fuel mixture may be poor, or the viscosity of the lubricating oil may be high. , stable idling cannot be achieved unless the engine rotational speed is increased to a certain level. For this reason, in conventional engines, when the engine temperature is below a predetermined value, the throttle valve opening of the engine in the idle state is slightly increased to increase the idle speed and enable stable idle operation. Some devices perform idle control.

However, this fast idle control has a problem in that it is not possible to control the idle rotation speed to the most suitable value for the actual temperature of the engine. Additionally, although this fast idle control does not take into account the engine load at all, idling is not necessarily performed under completely no-load conditions, and it is necessary to drive the torque converter of an automatic transmission, drive the air conditioner, etc. It is not uncommon for a load to be added to the engine by driving the engine or turning on lighting equipment, and this load causes fluctuations in the idle speed of the engine. Therefore, maintaining the engine idle speed at a desired value under various load conditions becomes an important issue.

Under such circumstances, a method has been proposed in which electrical feedback control is performed to make the idle speed match a target speed set under certain operating conditions. For example, the idling speed control device disclosed in Utility Model Application Publication No. 55-137234 inputs various conditions such as the use of the air conditioner mentioned above in the form of input information to a calculation device, and the calculation device inputs each input information. The most suitable target idle rotation speed is calculated according to the combination of A pulse having a duty ratio proportional to the difference between the two rotational speeds is outputted, and based on this output, the electric actuation control device controls the diaphragm type negative pressure response means, thereby controlling the opening degree of the engine throttle valve. The idle speed is automatically controlled to a desired idle speed.

However, although these conventional idling speed control devices may provide somewhat satisfactory results under normal conditions, when the control system malfunctions, for example due to incorrect input of information to the arithmetic unit, electrically actuated control When a failure or the like occurs in the device, the idle speed may be controlled excessively, and the idle speed may become excessive. Such an excessive idling speed not only causes discomfort to the driver, but also may cause a dangerous situation such as unexpected start of the vehicle in a vehicle equipped with an automatic transmission.

Therefore, the present invention provides an idle speed control device that performs feedback control of the engine's idle speed to a target value, even when a control system failure occurs such as incorrect input of information to the arithmetic unit as described above. It is an object of the present invention to provide an engine idle rotation control device that can control the idle rotation speed so that it does not become abnormally large.

The operating conditions of a vehicle (engine) vary, and therefore the information input to the above-mentioned computing device changes from moment to moment. However, during normal operation, the idle speed is controlled by adjusting the throttle valve opening within a certain control range. should be sufficient. Therefore, the pressure within the pressure operating chamber of the diaphragm negative pressure response means that controls the opening degree of the throttle valve should also be within a certain pressure value range.

Therefore, in the engine idle rotation control device according to the present invention, the abnormality detection device detects that the pressure in the pressure operating chamber of the diaphragm type negative pressure response means has become abnormal, and generates an abnormal signal. The pressure-responsive actuator is adjusted by correcting the pressure in the pressure operation chamber by the pressure correction means based on the above-described pressure correction means, thereby correcting the idle rotation speed. Furthermore, the abnormal state of pressure in the pressure working chamber is
This refers to a state in which the pressure value is outside a predetermined pressure value range, or a state in which a certain value of pressure continues for a predetermined period of time or more.

According to the engine idle rotation control device of the present invention, the operating amount of the pressure-responsive actuator is prevented from exceeding a predetermined value by the abnormality detection device that detects an abnormal pressure state and the pressure correction means,
Since the idle speed is thereby maintained within a predetermined value range, the engine can be idled in a preferable state even if the control system fails.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an engine idle rotation control device according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a functional diagram of a carburetor engine 1 incorporating an idle rotation control device of the present invention.

As is clear from FIG. 1, the intake system of the carburetor engine 1 consists of an intake pipe section 2, a throttle valve 3, and an intake manifold 4. The operation of the throttle valve 3 is controlled by a diaphragm actuator 5, which is part of an idle rotation control device, so that its opening degree is set during idle operation.

The actuator 5 is a diaphragm actuator having a diaphragm 6 and a pressure operating chamber 7 defined by the diaphragm 6. When the pressure in the pressure working chamber 7 becomes low, the diaphragm 6 moves to the left in the figure, thereby causing the connecting rod 8 fixed to the diaphragm 6 to move to the left.
The throttle valve 3 is slightly opened via the . In addition, at the tip of this connecting rod 8, when this connecting rod moves to the left together with the diaphragm 6,
A hook 8a is attached so that the throttle valve 3 can be rotated clockwise (opening direction) in the figure.
is provided.

The pressure working chamber 7 is communicated with the upstream side of the throttle valve 3 of the intake pipe section 2 through an atmospheric pipe line 9, and is communicated with the downstream side of the throttle valve 3 of the intake pipe section 2 via a negative pressure pipe line 10. is communicated with. A first solenoid valve 11 which is a normally open valve is disposed in the atmosphere pipe 9, and a second solenoid valve 12 which is a normally closed valve is disposed in the negative pressure pipe 10. Therefore, in the normal state, the pressure operating chamber 7 is maintained at atmospheric pressure, and the actuator 5 is configured to set the throttle valve 3 at the minimum opening corresponding to normal idling operation.

The first and second solenoid valves 11 and 12 are controlled so that when one is in an operating region, the other is in a non-operating region, and this control is performed by a microcomputer 13. The microcomputer 13 includes, for example, idle operation information D1 from an idle detection device 14 that detects the closed state of the throttle valve 3 to detect the idle operation state of the engine, and engine temperature information from a water temperature sensor 15 that detects the engine temperature. Information D2, air conditioner ON-OFF from air conditioner drive switch 16
information D3, and actual idle rotation speed information D from the rotation detector 17 that detects the engine rotation speed.
Engine operating state information such as No. 4 is input.

Although the above-described configuration can also perform idle rotation control to a certain degree, in this configuration, the idle rotation speed may be excessively controlled due to a failure in the control system, etc., as described above. Therefore, the idle rotation control device of the present invention includes a control correction device 20 as shown below. The details of this control correction device 20 are shown in an enlarged scale in FIG.

The control correction device 20 has a correction pipe 21 for communicating the pressure working chamber 7 of the actuator 5 with the atmosphere, in addition to the atmospheric pipe 9. This correction pipe 2
1 is provided with a third solenoid valve 22 which is a normally open valve.

On the other hand, the diaphragm type actuator 5 has
A pressure detector 23 for detecting the pressure within the pressure working chamber 7 is provided, and an output end of the pressure detector 23 is connected to an interface of the microcomputer 13.

Next, the operation of the idle rotation control device having the structure described above will be explained with reference to the flowchart shown in FIG. In addition, in the flowchart of Fig. 3, the flowchart symbols attached to the left side ~
is one cycle of control, and control is performed for one cycle per revolution in synchronization with the rotation of the engine.

The engine starts and the microcomputer 13
When activated, it is first determined whether or not the vehicle is idling based on the idling operation information D1 (). here,
When it is determined that the engine is idling, the engine temperature, cooler operating state, and other operating conditions are detected (), and then a target idle rotation speed Nset is calculated based on information D2, D3, etc. (), and this target idle rotation speed is Nset is stored in the memory m of the microcomputer 13. After this, the actual idle speed Nrpm (according to information D4) is detected (),
This actual idle speed Nrpm is also determined by computer 1.
3 is input. The computer 13 calculates the calculated target idle rotation speed in the central processing unit CPU.
Nset and the detected actual idle rotation speed Nrpm are compared and calculated, and a pulse-shaped correction signal S having a duty ratio corresponding to the difference between these two rotation speeds is generated. This operation is performed by the formula I=(Nset−Nrpm)+I
It is carried out by. Here, I is an integral output value. This correction signal S is the first solenoid valve 1 on the atmosphere side.
1, and an open signal S2, which is supplied to the second solenoid valve 12 to open the second solenoid valve 12 on the negative pressure side.

The first and second solenoid valves 11 and 12 are controlled by the close signal and the open signal S1 and S2, which are pulse signals with a duty ratio proportional to the amount of rotational speed to be corrected, as described above. ), therefore, the air in the pressure working chamber 7 is sucked in proportion to the amount of rotational speed to be corrected. The diaphragm 6 moves to the left with a stroke corresponding to this suction amount, and the connecting rod 8 moves to the left accordingly, and as a result, the throttle valve 3 opens to an opening corresponding to the amount of rotation speed to be corrected. only opened.

As described above, control is performed according to various conditions of the idle rotation speed.

However, as described above, there is a risk that the idle rotation speed may be excessively controlled due to a failure of the control system or the like.

Therefore, the computer 13 detects the pressure detector 23.
Upon receiving the pressure value information D5 corresponding to the pressure P in the pressure working chamber 7 detected by or pressure P
It is programmed to determine whether or not the controller has entered an abnormal state (), and to generate an abnormal signal S3 when this determination is YES. This abnormal signal S3 is
This is supplied to the third solenoid valve 22, and this third solenoid valve 22 is opened when this abnormality signal S3 is supplied (). By opening the third solenoid valve 22, the pressure operating chamber 7 of the actuator 5 is communicated with the atmosphere, and the pressure within this pressure operating chamber 7 increases, causing the diaphragm 6 to move to the right. The throttle valve 3 is closed and the rotational speed is corrected in the direction of deceleration.

In the embodiment described above, the abnormal state of the pressure P in the pressure operating chamber 7 of the diaphragm actuator 5 is set as when this pressure P becomes below the predetermined minimum value Pmin. It can be set as a state in which P remains below a predetermined minimum value Pmin for a predetermined period of time or longer.

An embodiment of the operation of the idle rotation control device of the present invention in this case will be described with reference to the flowchart of FIG.

A feature of this embodiment is that a step for determining whether the P<Pmin state has continued for a predetermined time or more is provided between the two steps indicated by the flowchart symbols in FIG. Note that the other steps are the same as those shown in FIG. 3, so the same flowchart symbols are given, and the explanation thereof will be omitted.

When it is determined in step that P<Pmin, the computer 13 determines whether this state continues for a predetermined time (), and if this determination is
When YES, the abnormal signal S3 is output for the first time and the third
This opens the solenoid valve 22. The determination in this step is, for example, by integrating the portion of the output signal from the pressure detector 23 that exceeds the threshold level corresponding to the predetermined minimum value Pmin, and
Alternatively, this can be done by comparing with the output signal from a monostable multivibrator.

According to this embodiment, the pressure P in the pressure working chamber 7
Correction is performed only when the pressure has been abnormal for a predetermined period of time or longer. Therefore, there is an advantage that correction is not performed when the output signal of the pressure detector 23 momentarily indicates a pressure abnormality due to noise or the like, but correction is performed only when correction is truly required.

Furthermore, in the above embodiment, an example was explained in which the present invention is applied to a throttle type idle rotation control device of the type that achieves control of idle rotation by adjusting the opening degree of a throttle valve. , a bypass pipe is provided in the intake pipe,
It is clear that the present invention can be applied to a bypass idle speed control device of the type that controls the idle speed by adjusting the amount of additional intake air provided by the bypass pipe.

Note that if the computer 13 is configured to issue an alarm signal such as sound or light when it detects the above-mentioned abnormal state of pressure, the driver will be able to know of a failure in the control system, etc., and control will be performed based on this. Repairs to systems, etc. can be carried out at an early stage.

[Brief explanation of drawings]

FIG. 1 is a structural functional diagram of an idle rotation control device of the present invention incorporated into a carburetor engine, and FIG. 2 is an enlarged view showing the main parts of the idle rotation control device shown in FIG. 1. FIG. 3 is a flowchart showing an example of the operation of the idle rotation control device of the present invention, and FIG. 4 is a flowchart illustrating an operation mode different from the operation shown in the flowchart of FIG. 3. . DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe section, 3... Throttle valve, 5... Diaphragm type actuator, 6... Diaphragm, 7... Pressure operation chamber, 9
... Atmospheric pipe line, 10... Negative pressure pipe line, 11, 12...
...first and second solenoid valves, 13...microcomputer, 20...control correction device, 21...correction pipe line, 22...third solenoid valve, 23...pressure detector.

Claims (1)

[Scope of Claims] 1. A rotation detector for detecting the engine rotation speed, a flow control valve for controlling the amount of intake air supplied to the engine in order to adjust the engine rotation speed, and a pressure-operated chamber. a pressure-responsive actuator that drives and controls the flow rate control valve according to an indoor pressure value, and a target idle rotation speed that is set according to the operating state of the engine and an actual idle rotation speed that is detected by the rotation detector. A difference between the two speeds is detected by comparison, and the actuator is operated to drive and control the flow rate control valve so that the idle rotation speed becomes the target idle rotation speed based on the difference between the two speeds. In an engine idle rotation control device having an actuator control means for controlling the pressure in the pressure working chamber, detecting that the pressure in the pressure working chamber of the actuator is outside a predetermined pressure range and generating an abnormal signal. An engine characterized by comprising: an abnormality detection device; and a correction means for correcting the pressure in the pressure working chamber based on the abnormality signal from the abnormality detection device and controlling the operation of the actuator in an engine deceleration direction. Idle rotation control device. 2. The abnormality detection device is configured to detect that the pressure within the pressure working chamber continues to be outside the predetermined pressure range for a predetermined period of time or more, and generate the abnormality signal. An engine idle rotation control device according to claim 1.