JPH0324849Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of industrial application This invention relates to an idle speed control device for an internal combustion engine, and in particular controls the idle speed by adjusting the opening degree of the carburetor throttle valve using an electric actuator. The present invention relates to a device that performs

B. Prior art FIG. 1 shows an electric actuator 4 that engages with the movable end of a throttle lever 3 that opens and closes a throttle valve 2 of a carburetor 1 in an idle rotation speed control device.
Equipped with A water temperature sensor 5 detects the coolant temperature of the engine 9 and sends it to the control circuit section 8 . Control circuit section 8
compares the rotation speed detected by the trigger signal of the ignition coil 6 and the target idle rotation speed according to the cooling water temperature, and sends an operation signal according to the difference to the electric actuator 4 to control the throttle valve 2. By adjusting the idle opening degree, the idle rotation speed is controlled to the target value. Although not shown, a switch is provided to detect various loads caused by changes in engine speed, and the signals thereof are input to the control circuit section 8 to control the engine speed to a target speed corresponding to the load.

This idle speed control device adjusts the opening degree of the throttle valve 2 by moving the tip 24 of the electric actuator 4 back and forth in the left and right directions in the figure. Since the movable end of the throttle lever 3 is pressed against and comes into contact with the tip 24 of the electric actuator 4 only during idle operation when it is almost closed, the presence or absence of this contact can be detected by a method built into the electric actuator 4, which will be described later. The touch switch 18 detects it and determines whether it is in idle operation or not, and only while it is in contact, the electric actuator 4 adjusts the idle opening of the throttle valve 2 to set the idle speed of the internal combustion engine to the target value. I was starting to take control.

The electric actuator 4 has the structure shown in FIG. 2, where 10 is a DC motor, 11 and 12 are electric wire connection terminals of the DC motor, and 13 is a group of reduction gears including gears fixed to the motor output shaft. 14,15
17 is the final stage gear and screw integrated into the output shaft 15, and 17 is a screw nut screwed into the screw 15, which moves forward and backward in the left and right directions by forward and reverse rotation of the screw 15, and has a structure in which rotation is prevented by the guide portion 20. There is. The touch switch 18 is opened when the output shaft 16 receives the load of the back spring 22 and is restrained by the plate 20, and is loaded with the load from the throttle lever 3.
As the back spring 22 contracts and the thrust bearing 23 receives a load, the contact spring of the touch switch 18, which engages with the output shaft 16, pinches and the switch contact becomes closed. 20 is a guide that supports the forward and backward movement of the screw nut 17; 21, 2;
5 is a rotation bearing of the output shaft 16; 24 is a tip portion press-fitted into the tip of the screw nut 17; 19 is a position detector, which is a potentiometer that outputs a voltage corresponding to the position of the screw nut 17; The movable member 19a is fitted into the engagement portion 17a of the screw nut 17.

When the throttle valve 2 changes from the open state to the closed state shown in FIG. 1, the throttle lever 3 comes into contact with the tip 24 of the electric actuator 4. In this way, when the closing force of the throttle lever is applied to the tip 24, the screw nut 17 and output shaft 16 shown in FIG. , the applied load will be applied to the bearing 23. During this process, the contact of the touch switch 18 closes, detecting that the opening degree of the throttle valve 2 is the idle opening degree, and the position detector 19 engaged with the screw nut 17.
A voltage signal corresponding to the position of the screw nut was inputted to the control circuit section 8 by the screw nut. Here, the operation signal from the control circuit section 8 is transmitted to the electric actuator 4.
When the DC motor 10 enters the DC motor terminals 11 and 12, the DC motor 10 rotates forward or reverse, and transmits rotation to the output shaft 16 via the reduction gear group 13. The screw nut 17 is screwed into the screw 15, and the cover 20 has a guide groove to prevent rotation, so that the screw nut 17 moves linearly forward and backward according to the rotational movement of the screw 15.

Symbol R indicates that when the throttle valve 2 is at idle opening, the screw nut 17 and the output shaft 1
5 is a relief stroke that retreats to the right.

C. Problems to be Solved by the Invention The conventional idle speed control device described above uses the touch switch 18 to determine whether the throttle lever is in the control range (that is, whether the throttle lever is in contact with the electric actuator). The structure was complicated, and there were problems with durability in terms of the lifespan of the touch switch contacts.

In view of the above, this idea is based on the touch switch 1.
The purpose of this invention is to propose an idle rotation speed control device that eliminates the 8.8, has a simpler structure, and has improved durability.

D. Means for solving the problem In this invention, when the load of the throttle lever is applied to the electric actuator, the output shaft 16 and the screw nut 17 move back to the right by the relief stroke R, and the throttle lever When the load is removed, the screw nut 17 moves to the left along with the output shaft 16 by the relief stroke R to recover, which is detected by the change in the output voltage of the position detector 19. Moreover, this voltage change is caused by the rotation of the motor 10. It is detected from the fact that the motor is not energized that it is not due to the advance or retreat of the nut 17, and it is possible to know whether the throttle lever load is applied or released by the electric actuator by comprehensively judging both detection results.

That is, the idle rotation speed control device of this invention uses a screw 15 provided on an output shaft 16 that is rotationally driven from a direct motor 10 via a reduction gear 13.
A screw nut 1 is screwed onto this screw 15 and can move linearly forward and backward in the axial direction of the output shaft 16.
7, and a position detector 19 that engages with this screw nut 17 and converts the position of the screw nut 17 into a voltage, so that the load of the throttle lever 3 of the carburetor throttle valve 2 is applied to the screw nut 17. an electric actuator 4 having a structure in which the screw 15 and the screw nut 17 integrally advance and retreat by a relief stroke R as the voltage applied to the screw 17 is released; and a control circuit section 8 for driving the DC motor 10. DC motor 1
By detecting that energization to 0 is cut off and detecting a change in the output voltage of the position detector 19 in this state, it is possible to determine whether the throttle lever load is applied to or released from the electric actuator. It is designed to be detected.

Embodiment FIG. 3 shows an embodiment of the electric actuator 4 used in this invention. Compared to the conventional one shown in FIG. The difference is that it is slightly larger.

The electric actuator 4 shown in FIG. 3 and the control circuit section 8 shown in FIG. 4 are incorporated into the device shown in FIG. 1 to constitute an idle speed control device.

Next, an example will be explained using the flowchart shown in FIG.

FIG. 4 shows a specific example of the control circuit section 8, in which a trigger signal from the ignition coil 6 is inputted via the waveform shaper 26 to the microcomputer CPU, which is controlled according to the program in the storage circuit ROM. In addition, the signal from the water temperature sensor 5 is
The signal is converted into a digital signal by the D converter 27 and inputted via the I/O port 28. Also, position detector 1
9, a constant voltage is applied across all resistances, and changes as the screw nut 17 operates. Position detector 1
The L section voltage of 9 is input to the microcomputer CPU via the A/D converter 27 and the I/O port 28. Furthermore, the DC motor 10 includes a position detector 19, a water temperature sensor 5, and an induction coil 6.
A screw nut direction control signal is supplied from the I/O port 29 of the microcomputer CPU via the drive circuit 30 by the position detector 19 which engages the screw nut with the target position 17 based on the signal from the microcomputer CPU. be done. Next, the idle state determination function using the position detector will be explained according to the flowchart of FIG.

In the engine operating state, in order to determine whether the actuator 4 is controlling the idle speed of the engine, the microcomputer CPU determines whether the DC motor 10 is energized. When the load of the throttle lever 3 is applied to or released from the actuator 4 during de-energization, the voltage change of the position detector 19 that changes accordingly is detected. When the voltage changes, the old voltage value before the change and the new voltage value after the change are compared, and if the new voltage value becomes large, the touch switch flag of the microcomputer CPU is set, and if the new voltage value becomes small, the microcomputer CPU's touch switch flag is set. Clears the touch switch flag of the computer CPU and changes the new voltage value to the old voltage value. Based on this operation, it is detected that the load of the throttle lever 3 is applied to or released from the actuator 4.

F. Effects of the invention In this invention, the microcomputer program detects that the DC motor is in a de-energized state and the voltage change of the position detector 19, thereby determining that the throttle lever is in contact with the electric actuator. (In other words, being in an idle state)
Since the touch switch 18 can be detected, the touch switch 18 can be eliminated, which has the advantage of simplifying the structure and improving durability.

[Brief explanation of the drawing]

Figure 1 is a partial vertical cross-sectional view of an idle speed control device, Figure 2 is a partial vertical cross-sectional view of a conventional electric actuator, and Figure 3 is a partial vertical cross-sectional view of an embodiment of the electric actuator used in this invention. A plan view, FIG. 4 is a specific example of the control circuit section used in this invention, and FIG. 5 is a flowchart of the idle state determination function of the device of this invention. 1... Carburetor, 2... Throttle valve, 3...
...Throttle lever, 4...Electric actuator, 8...Control circuit section, 9...Engine, 10...
... DC motor, 13 ... Reduction gear group, 14 ... Final stage gear, 15 ... Screw, 16 ... Output shaft, 17 ... Screw nut, 19 ... Position detector, CPU ... Microcomputer.

Claims (1)

[Scope of utility model registration request] A screw 15 is provided on an output shaft 16 that is rotationally driven by a DC motor 10 via a reduction gear 13.
A screw nut 1 is screwed onto this screw 15 and can move linearly forward and backward in the axial direction of the output shaft 16.
7, and a position detector 19 that engages with this screw nut 17 and converts the position of the screw nut 17 into a voltage, so that the load of the throttle lever 3 of the carburetor throttle valve 2 is applied to the screw nut 17. an electric actuator 4 having a structure in which the screw 15 and the screw nut 17 integrally advance and retreat by a relief stroke R as the voltage applied to the screw 17 is released; and a control circuit section 8 for driving the DC motor 10. DC motor 1
By detecting that energization to 0 is cut off and detecting a change in the output voltage of the position detector 19 in this state, it is possible to determine whether the throttle lever load is applied to or released from the electric actuator. An internal combustion engine idle speed control device that detects this.