JPH0243021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an idle speed control system mainly applied to automobile engines.

[Prior Art] Modern automobile engines are equipped with various systems to improve fuel economy, but one of them is that few of them employ an idle speed control system. do not have.

As a prior art related to this type of control system, for example, there is one disclosed in Japanese Patent Application No. 135522/1982. That is, this idle rotation speed control system includes a rotation speed detection means for detecting the rotation speed of the engine, and an actuator that locks the rotating part of the throttle valve that returns to the closing direction by itself. an opening adjustment mechanism that adjusts the closing position of the throttle valve by moving forward and backward; and an opening adjustment mechanism that elastically receives the contact pushing force when the rotating part contacts an actuator of the opening adjustment mechanism. An idle switch that has a movable contact that retreats and switches the idle switch to a conductive state by bringing the retreated movable contact into elastic contact with a stationary contact, and controls the opening adjustment mechanism in an operating range where the idle switch is maintained in a conductive state. Feedback control means is provided for controlling the forward and backward positions of the actuator so that the engine rotation speed detected by the rotation speed detection means converges to the target rotation speed. The target rotational speed is updated in accordance with the engine cooling water temperature, so that the idle rotational speed can be stably maintained at the lowest possible value within a range that does not cause engine stall.

However, if this is the case, there may arise a problem that the consistency of the control is impaired due to the so-called play of the idle switch.

FIG. 4 is an explanatory diagram for specifically explaining this problem. In the figure, 1 is a carburetor of an automobile gasoline engine, 2 is a throttle valve of this carburetor 1, and 3 is a throttle valve of this throttle valve 2. A rotating portion 4 is a spring that biases the throttle valve 2 in the closing direction, and 5 is an accelerator pedal that biases the throttle valve in the opening direction via a wire 6. 7 is the throttle valve 2
An opening adjustment mechanism 8 is an idle switch provided in association with the opening adjustment mechanism 7, which locks the rotating portion 3 of the throttle valve 2 to adjust the closed position of the throttle valve 2.

The opening adjustment mechanism 7 includes a feed screw portion 13 provided on the output shaft 12 of the DC motor 11, and a cap nut-shaped actuator 14 screwed into the feed screw portion 13. By being actuated by a signal from the feedback control means, the actuator 14, whose rotation is prohibited by a guide member (not shown), is screwed back and forth in the axial direction. The idle switch 8 has a movable contact 15 that elastically retreats in response to the contact pushing force when the rotating portion 3 contacts the actuator 14 of the opening adjustment mechanism 7. The retracted movable contact 15 is brought into elastic contact with the stationary contact 16 to switch to a conductive state. Specifically, the output shaft 12 of the DC motor 11 is supported so that it can freely move in the axial direction within a certain range, and is elastically biased in the forward direction with a weak force.
The movable contact 15 is held through an insulating member 17, and the stationary contact 16 is supported by a fixed housing 18. Therefore, this switch 8 is the throttle valve 2 of the carburetor 1.
When the rotating part 3 is away from the actuator 14, the output shaft 12 is held in the forward position A and the movable contact 15 is away from the stationary contact 16, so it is maintained in a non-conducting state. (5th
(see Figure a), when the rotary part 3 contacts the actuator 14 and the output shaft 12 is pushed back to the retracted position B by the contact pushing force, the movable contact 1
5 comes into contact with the stationary contact 16 and switches to a conductive state (see FIG. 5c). by the way,
In such a configuration, in order to ensure contact pressure between the movable contact 15 and the stationary contact 16 and maintain a reliable conduction state, the output shaft 12 is moved from the forward position to the backward position. The movable contact 15 and the stationary contact 16 are set to start contacting each other at C while retreating to position B, and after contact, the output shaft 1 is further moved by an amount of play L.
2 elastically deforms the contact 16 while being retracted to ensure proper contact contact pressure. However, if this is the case, a problem arises when, for example, the accelerator pedal 5 is depressed within the range of the free play L from the idling state (see FIG. 5c). That is,
When the driver lightly places his foot on the accelerator pedal 5 from an idling state, the throttle valve 2 opens slightly and the engine speed increases slightly.
At this time, if the opening amount of the throttle valve 2 is small and the operating amount of the rotating portion 3 is less than the play amount L (in the case where it is in an intermediate state between b and c in FIG. 5), the idle switch is 8 will maintain the conductive state, and the opening adjustment means 7 will still be under the control of the feedback control means. Therefore, if the engine speed increases even slightly, the feedback control means erroneously determines that the idle speed has naturally increased, and sends a signal to the opening adjustment means 7 indicating that the idle speed should be lowered. In other words, a signal indicating that the actuator 14 should be moved backward is output. Therefore, if you release your foot from the accelerator pedal 5 in this state, the actuator 14 will have moved back to an unexpected position, causing the throttle valve 2 to momentarily close too much. This causes the inconvenience that the engine rotation becomes temporarily unstable or stops.

[Problems to be Solved by the Invention] The present invention has been made with attention to the above-mentioned circumstances, and it is possible to reliably solve the problem that the consistency of control is impaired due to the so-called play of the idle switch. The purpose is to eliminate it.

[Means for solving the problem] In order to achieve such an object, the present invention has the following features:
As shown in FIG. 1, the rotation speed detection means 26 detects the rotation speed of the engine, the opening detection means 30 detects the opening degree of the throttle valve 2, and the throttle valve 2 self-returns to the closing direction. an opening adjustment mechanism 7 that has an actuator 14 that locks the rotating portion 3 of the throttle valve 2 and adjusts the closed position of the throttle valve 2 by moving the actuator 14 forward and backward; and an operation of the opening adjustment mechanism 7. It has a movable contact 15 that moves elastically in response to the contact pushing force when the rotary part 3 contacts the child 14, and the moved movable contact 15 is brought into elastic contact with the stationary contact 14 to be in a conductive state. An idle switch 8 that switches to
In the operating range where the idle switch 8 is maintained in a conductive state, the opening adjustment mechanism 7 is controlled so that the engine rotation speed detected by the rotation speed detection means 26 approaches the target idle rotation speed. Feedback control means 9 for controlling the forward and backward positions of the actuator 14; Erroneous operation prevention means 1 that stops the opening adjustment mechanism 7 at that position or returns it to the operating position before the elapse of a certain period of time when it is confirmed that the opening of the tutle valve 2 does not change in the control direction.
0.

[Operation] According to this means, from an idling state,
When the engine speed increases slightly due to placing your foot on the accelerator pedal, etc., first, a signal is output from the feedback control means 9 to the opening adjustment means 7 indicating that the idling speed should be lowered, and the operating element 14 is forced back. However, if the engine speed is increasing due to foot rest, etc., even if the closing position of the throttle valve 2 is changed by moving the actuator 14, the opening degree of the throttle valve 2 will not follow it. never changes.
When the malfunction prevention means 10 confirms that the opening of the throttle valve 2 detected by the opening detection means 30 does not change in the control direction even after a certain period of time has elapsed since the output of the signal. At this time, the feedback control is temporarily stopped and the opening adjustment mechanism 7 is stopped on the spot or returned to the operating position before the elapse of the predetermined period of time. Therefore, when the footrest etc. are released and the throttle valve 2 self-returns to the closed position, the throttle valve 2 is locked at the proper position by the actuator 14 of the opening adjustment means 7. Therefore, problems such as engine breathing and engine stall do not occur.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 2 and 3.

Note that the same reference numerals are given to the same or corresponding parts as those shown in FIG. 4, and the explanation thereof will be omitted.

This system is similar to the one shown in Figure 4.
It is applied to an automobile engine, and in the figure, 1 is a carburetor, 2 is a throttle valve, and 3 is a rotating part of the throttle valve 2. The rotating portion 3 is lever-shaped and is configured to rotate integrally with a support shaft 2b that supports the throttle valve body 2a. Further, 7 is an opening adjustment mechanism, and the DC motor 11 of this opening adjustment mechanism 7 is driven by the pulsed application of DC voltage. The output shaft 12 is held so that it can move forward and backward by a certain distance in the axial direction with respect to the fixed frame 18 (distance corresponding to the forward position A to the backward position B), and is far more than the spring 4. It is urged forward (downward in the figure) by a weak spring (not shown). The actuator 14 screwed onto the output shaft 12 has a cylindrical main body 14a that is threaded onto the 12 threaded parts 13 of the output shaft, and a pressure receiving part 14b press-fitted into the tip of the main body 14a. The rotating portion 3 is locked at the tip of the pressure receiving portion 14b. Then, the main body part 1
A protrusion 14c protruding from the outer periphery of the fixed frame 18 is slidably fitted into an axial groove (not shown) provided in a cover attached to the front surface of the fixed frame 18, thereby inhibiting rotation. Further, 21 is a microcomputer system for controlling the opening adjustment mechanism 7, and serves as a feedback control means and a malfunction prevention means. This microcomputer system 21 includes a central processing unit (CPU) 22, a memory 23, and interfaces 24 and 25. and,
The interface 24 receives a signal a from the idle switch 8, a signal b from the rotation speed detection means 26, a signal c from the transmission state detection means 27, a signal d from the water temperature sensor 28, and a signal e from the vehicle speed sensor 29. The signal f from the opening detecting means 30 and the opening detecting means 30 are respectively input, and the drive signal g is output from the interface 25 to the opening adjusting means 7. The idle switch 8 has a movable contact 15 held by an insulating member 17 fixed to the output shaft 12 and a stationary contact 16 supported by a fixed frame 18, and is shown in FIGS. 4 and 5. It has exactly the same configuration as shown in . In addition, the rotation speed detection means 2
Reference numeral 6 is for detecting the rotational speed of the engine, and uses, for example, an ignition pulse. In addition, the transmission state detection means 27
This is to detect whether or not the transmission state between the engine and the drive wheels is disconnected.It is used to detect whether the transmission state between the engine and the drive wheels is disconnected or not, and when the clutch switch or transmission, which changes depending on whether the clutch is engaged or not, is shifted to the neutral position. This corresponds to a neutral switch, etc. The water temperature sensor 28 is for detecting the engine cooling water temperature, and includes, for example, a thermistor that converts the water temperature into an analog electrical signal, and an A/R that converts the output of this thermistor into a digital electrical signal.
It is equipped with a D converter. Further, the opening detecting means 30 is for detecting the opening of the throttle valve 2, and includes, for example, a potentiometer that converts the amount of rotational displacement of the rotating portion 3 into an electric signal.
It is equipped with an A/D converter that converts the output of this potentiometer into a digital electric signal.

Then, the microcomputer system 2
1 is programmed to operate according to a procedure as schematically shown in FIG. First, in step 51, each signal a, b, c,
Enter d, e, f. Also, in step 52, it is determined whether the engine is started.
This is determined based on whether or not the engine rotation speed detected by the rotation speed detection means 26 exceeds, for example, 500 rpm. Also, step
In step 53, it is determined whether the idle switch 8 is in a conductive state (ON), and in step 54,
It is determined whether the vehicle speed detected by the vehicle speed sensor 29 is, for example, less than 2.8 km/hr, and in step 55 it is determined whether the transmission system is in a non-transmission state. If all of the conditions in each of these steps 52 to 55 are satisfied, the process moves to step 56, while if any of the conditions are not satisfied, the process returns to step 51 and repeats the same process at a different time point. Repeat procedure. When proceeding to step 56, the target idle rotation speed N ₁ is determined according to the engine cooling water temperature detected by the water temperature sensor 28.
is looked up from a table stored in the memory 23. Then, in step 57, the target idle rotation speed N ₁ and the actual engine rotation speed detected by the rotation speed detection means 26 are determined.
Compare with N ₂ . As a result, if the difference between the actual engine speed N ₂ and the target idle speed N ₁ does not exceed the allowable value (for example, ±20 rpm), there is no need to operate the opening adjustment mechanism 7. , return to step 51, and repeat the same procedure at a different time point. Conversely, the actual engine speed N ₂
If the difference between the target idle rotation speed _N1 and the target idle rotation speed N1 exceeds the above-mentioned tolerance value, the process proceeds to step 58. step
At step 58, after determining the direction in which the opening adjustment means 7 should be operated, a command is issued to apply one pulse of voltage to the DC motor 11 of the opening adjustment means 7. That is, the actual engine speed N ₂ is
If it is higher than the target idle rotation speed _N1 , the motor 11 is operated by one pulse in the direction in which the actuator 14 moves backward, and the actual engine rotation speed is
When N ₂ is lower than the target idle rotation speed N ₁ , the motor 11 is operated in a direction in which the actuator 14 moves forward. After operating the DC motor 11 of the opening adjustment means 7 for one pulse in this manner, in step 59, the system waits until a certain period of time (for example, 1 second) has elapsed, and then, in step 60, the opening A new signal from the degree detection means 30 is input. Then, in step 61, it is determined whether the throttle opening detected by the opening detecting means 30 has changed in the control direction. As a result, if it is confirmed that the throttle opening has changed in the control direction, it is determined that normal feedback control is being performed, and the process returns to step 51 to repeat the same procedure. On the other hand, if it is confirmed that the throttle opening does not change in the control direction, that is, even though the DC motor 11 is operated in the direction in which the actuator 14 moves backward, the throttle opening detected in step 60 If it is confirmed that the opening has not changed by an appropriate value compared to the throttle opening detected before the DC motor was activated, it is determined that normal feedback control is not being performed, and the process proceeds to step 62. Transition. In step 62, a command is issued to operate the DC motor 11 of the opening adjustment means 7 by one pulse in the direction opposite to the direction in which it was operated in step 58, and then the process returns to step 51.

With this kind of configuration, steps 51-57→51 or steps 51-61→
The procedure 51 is repeated, and normal feedback control is performed to maintain the idle speed within an appropriate range depending on the water temperature. On the other hand, when the throttle valve 2 opens slightly within the range where the idle switch 8 does not switch to the non-conducting state (within the free play L range), such as when the driver lightly places his foot on the accelerator pedal 5. In this case, the engine speed increases without the above-mentioned feedback control being released, so steps 57 to 58 are performed.
Then, the DC motor 58 of the opening adjustment means 7 is driven by one pulse in the direction of retracting the actuator 14. However, in this case, the throttle valve 2 is opened by depressing the accelerator pedal 5, so even if the motor 11 is operated and the actuator 14 is moved backward, the throttle valve 2 is opened by pressing the accelerator pedal 5. There is no possibility of closing following the control. Therefore, in this case, the step
Step 61 then proceeds to step 62, where the motor 11 is reversely driven by one pulse in the direction of advancing the actuator 14. While the accelerator pedal 5 continues to be pressed down slightly, the control is repeated in the order of steps 51 to 62→51. Therefore, no matter at what point the accelerator pedal 5 is released, the actuator 14 will remain in the correct position, causing inconveniences such as temporary engine malfunction or engine stalling. does not occur.

In the above embodiment, when it is confirmed that the throttle opening detected by the opening adjustment means does not change in the control direction even after a certain period of time has elapsed after the opening adjustment mechanism was activated, the Although the case where the opening adjustment mechanism is returned to the operating position before the elapse of a certain period of time has been described, the present invention is not necessarily limited to such a case; for example,
The opening adjustment mechanism may be stopped at its operating position until the change is detected.

[Effects of the Invention] Since the present invention has the above configuration, the following effects can be obtained.

First, if the throttle opening can no longer follow the control while controlling the idle speed through feedback control, the feedback movement of the actuator of the opening adjustment mechanism will be temporarily prohibited. Therefore, the consistency of control will not be impaired due to so-called play in the idle switch. That is, it is possible to reliably eliminate inconveniences such as the engine stalling or stopping when the foot is released from the accelerator pedal.

In addition, the opening of the throttle valve that is directly driven by the opening adjustment mechanism is detected, and based on the detected value, it is confirmed whether the feedback control is being performed normally. It is possible to ensure and speed up the operation, and it is possible to perform appropriate malfunction prevention control with high responsiveness.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram for clearly demonstrating the present invention.
FIG. 2 is a schematic configuration explanatory diagram showing one embodiment of the present invention, FIG. 3 is an explanatory diagram for explaining the control procedure in the same embodiment, FIG. 4 is a schematic configuration explanatory diagram showing a conventional example, and FIG. Figures a, b, and c are explanatory diagrams of the operation of the conventional example. DESCRIPTION OF SYMBOLS 1... Carburetor, 2... Throttle valve, 3... Rotating part, 7... Opening adjustment means, 8... Idle switch,
9... Feedback control means, 10... Malfunction prevention means, 11... DC motor, 12... Output shaft, 15...
Movable contact, 16... Stationary contact, 21... Microcomputer, 26... Rotation speed detection means, 30... Opening degree detection means.

Claims (1)

[Claims] 1. A rotation speed detection means for detecting the rotation speed of the engine, an opening detection means for detecting the opening degree of the throttle valve, and an actuator for locking the rotating part of the throttle valve that returns to the closing direction by itself. an opening adjustment mechanism that adjusts the closed position of the throttle valve by moving the actuator forward and backward; and a contact pushing force when the rotating part abuts the actuator of the opening adjustment mechanism. An idle switch has a movable contact that moves elastically in response to the contact, and the idle switch has a movable contact that moves elastically in response to the contact, and the idle switch has a movable contact that elastically moves with the stationary contact to switch the idle switch to a conductive state. feedback control means for controlling the forward and backward positions of the actuator so that the engine rotation speed detected by the rotation speed detection means approaches the target rotation speed by controlling the opening adjustment mechanism; When it is confirmed that the throttle opening detected by the opening detection means does not change in the control direction even after a certain period of time has elapsed after the opening adjustment mechanism is activated, the opening adjustment mechanism is stopped at that position. An idle speed control system for an engine, characterized in that it is equipped with a malfunction prevention means for causing the engine to stop or return to the operating position before the elapse of a certain period of time.