JPH0468457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a throttle valve control device for an engine.

[Problems to be solved by conventional technology and invention]

In recent years, electrically controlled throttle valve control devices have been developed for the purpose of smooth and easy driving and improved fuel efficiency.

This type of throttle valve control device is generally equipped with an actuator that controls the throttle valve opening according to the movement of the accelerator pedal or the operating status of the engine. Since the actuator is an important device that controls driving force, it has a structure that allows for manual control even in the event of an actuator failure, in order to avoid danger, secure traffic, and enable prompt return to a repair shop in the event of a failure. desired.

As a prior example that satisfies these demands, for example, the throttle valve control device described in JP-A-59-122742 returns the throttle valve to the fully closed position by the action of a return spring when the throttle valve electric control device fails. At the same time, the accelerator pedal is mechanically connected (engaged and connected) to the throttle valve via a throttle valve mechanical control mechanism to enable control. However, in this case, the elasticity of the return spring is constantly acting on the throttle valve, so the load on the actuator is large.As a result, the actuator becomes larger and takes up more space, and the operating speed of the actuator becomes slower. There was a problem that the controllability deteriorated as a result.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a throttle valve control device that occupies less space and provides better controllability.

[Means and actions for solving problems]

The throttle valve control device according to the present invention is equipped with an actuator that controls the opening degree of the throttle valve according to the movement of the accelerator pedal and the operating state of the engine, and when the actuator fails, the throttle valve is activated by the return spring. In an engine throttle valve control device in which the accelerator pedal and the throttle valve are mechanically connected to each other, the return spring is plastically deformed when the temperature is below the transformation point, and when the temperature is below the transformation point, the throttle valve is returned to the fully closed position. The return spring is made of an elastically deformable shape memory alloy, and when the actuator fails, the return spring is kept at a temperature above the transformation point, and when the actuator is normal, the return spring does not act on the throttle valve as a spring. As a result, the load on the actuator can be extremely small.

〔Example〕

Hereinafter, the present invention will be explained in detail based on an illustrated embodiment.

In FIG. 1, 1 is a carburetor intake shell, 2 is a throttle shaft pivotally mounted perpendicular to the carburetor intake shell 1, and 3 is a throttle fixed to the throttle shaft 2 within the intake shell 1. A pulley 4 is fixed to the externally protruding end of the throttle shaft 2 and has a contact pin 4a having a semicircular cross section implanted at a predetermined position in front of the pulley; 5 is an intake cylinder 1;
6 is a belt connecting the drive shaft 5a of the actuator 5 and the pulley 4; 7 is a tensioner that tensions the belt 6; The throttle valve 3 is opened and closed by turning it to the left.

8 is an accelerator pedal, 9 is a potentiometer P and a power source _E1 ; an accelerator pedal depression amount sensor that detects the amount of depression of the accelerator pedal 8 and outputs an accelerator pedal depression amount signal; 10 is a drive wheel speed 11 is a switch that issues a command signal for auto drive, etc. 12 is an actuator 5 that receives signals from the accelerator pedal depression amount sensor 9, the speed sensor 10, and the command switch 11.
This is an electronic control circuit such as a microcomputer that outputs a control signal to the return spring energization circuit and a failure mode signal to the return spring energization circuit described later. 1
3 consists of a switching transistor Tr and a power supply E ₂ , and the + side is connected to one end of a throttle valve return spring (described later) and the - side is connected to the intake body 1, respectively, and outputs an applied voltage when a failure mode signal is input. The return spring energizing circuit 14 has one end fixed in an insulated state to the intake shell 1 and electrically connected to the + side of the return spring energizing path 13, and the other end fixed in a conductive state to the pulley 4 and connected to the throttle. The shaft 2 is electrically connected to the negative side of the return spring energizing circuit 13 via the intake shell 1.
This is a throttle valve return spring stretched between and pulley 4. The throttle valve return spring 14 is made of a shape memory alloy that easily deforms plastically when the temperature is below the transformation point and deforms elastically when the temperature is above the transformation point.
When the actuator 5 is normal, the voltage applied by the energizing circuit 13 is zero, so it does not generate heat and is kept at a temperature below the transformation point, so it does not act as a spring.
When the actuator 5 is out of order, a current is applied to the actuator 5 to generate heat, and the temperature is kept above the transformation point, which acts as a spring and gives the pulley 4 a left-turning behavior, that is, a valve-closing behavior for the throttle valve 3. I'm starting to do that.

Reference numeral 15 denotes a fan-shaped throttle lever that is rotatably attached to the externally protruding end of the throttle shaft 2, and rotates freely until the right side edge engages the contact pin 4a when turning to the right. It is designed to rotate as one. 16 has one end connected to the throttle lever 15 and the other end connected to the accelerator pedal 8, and a damper 1 in the middle.
7 is an accelerator wire provided with a contact pin 4a and a pulley 4, which rotates the throttle lever 15 to the right according to the amount of depression of the accelerator pedal 8, and allows the throttle lever 15, which is linked to the accelerator pedal 8, to move quickly. When an overload is likely to be applied to the actuator 5 via the belt 6, the damper 17 is extended to prevent the overload. Reference numeral 18 is an accelerator return spring stretched between the throttle lever 15 and the intake cylinder 1, which gives the throttle lever 15 a left-turning behavior (returning behavior). Furthermore, damper 17
The operating load is the return force of the throttle valve return spring 14 and the accelerator return spring 1.
8 and the driving force of the actuator 5 and the accelerator return spring 18.
It is assumed that the value is set smaller than the sum of the return force and the return force.

Next, the operation of the throttle valve control device of the present invention will be explained.

First, the normal operation will be described assuming that the throttle valve opening changes linearly with the amount of depression of the accelerator pedal.

When the accelerator pedal 8 is depressed, the electronic control circuit 12 sends a signal with a length proportional to the amount of pedal depression (accelerator opening) to the actuator 5.
The actuator 5 turns the pulley 4 to the right and opens the throttle valve 3. As shown in FIG. 2, when the throttle valve is fully closed (when the accelerator pedal 8 is free), the throttle lever 15 If the angle between the right side edge of the contact pin 4a and the contact pin 4a is set to be θ, the third
When the amount of depression of the accelerator pedal 8 is changed from 1 to 2 to 5 in the figure, the angle of the throttle lever 15 changes from 0 to 2 to 3, and if the actuator 5 is operating normally. The throttle valve opening changes from 1 to 4. That is, the right edge of the throttle lever 15 and the contact pin 4a move while maintaining an angle θ.

By the way, in the throttle valve control device of the present invention, an appropriate opening degree of the throttle valve is selected depending on the amount of depression of the accelerator pedal and the operating state detected by the speed sensor 10 or the like. In that case, the throttle valve opening degree is 4th.
The change occurs within the shaded area of 1→6→4→7→1 shown in the figure. Also, at this time, the throttle lever 15 changes from 0 to 2 to 3 in the same manner as above. Therefore, if the angle θ between the right side edge of the throttle lever 15 and the contact pin 4a is appropriately set, the throttle lever 15 will not move during steady operation.
This means that the contact pin 4a does not come into contact with the contact pin 4a. That is, the mechanical control means does not interfere with the movement of the electrical control means.

However, the actuator 5 has transient characteristics, and in reality it cannot follow the accelerator pedal depression amount signal or command signal without delay. This is shown in FIGS. 5a and 5b, where A→B→C is the required value of the throttle valve opening, and A→D→E→C is the actual value. Here, in the case of FIG. 5b, where the movement of the throttle lever 15 in conjunction with the accelerator pedal 8 is relatively slow, the right edge of the throttle lever 15 does not come into contact with the contact pin 4a, but the movement is fast. In the case of FIG. 5a, the right edge of the throttle lever 15 pushes the contact pin 4a in the diagonally shaded area surrounded by H and D. However, as described above, since the operating load of the damper 17 is set smaller than the sum of the driving force of the actuator 5 and the return force of the accelerator return spring 18, the damper 17
extends, and as a result, the opening degree of the throttle lever 15 changes along a line passing through D below the shaded area in FIG. 5a, thereby preventing overload from being applied to the actuator 5.

Note that it is not always necessary to provide the damper 17, and if it is not provided, the rapid movement of the accelerator pedal 8 will act more than the movement of the actuator 5, and the throttle valve opening will change from A to H to E to C. This has the effect of improving acceleration.

During the above operation, the applied voltage generated in the return spring energizing circuit 13 remains zero and the throttle return spring 14 is not energized, and as a result, the return spring 14 is in a plastic deformation state with the temperature below the transformation point, so the actuator The load on 5 is extremely small.

Next, if the signal from the accelerator pedal depression amount sensor 9 and the signal from the speed sensor 10 are significantly inconsistent, the electronic control circuit 12 determines that the actuator 5 is malfunctioning, and at the same time stops power supply to the actuator 5. A mode signal is output to the return spring energizing circuit 13 and the energizing circuit 13
An applied voltage is generated to energize the throttle valve return spring 14. Then, the return spring 14 is heated to a temperature higher than the transformation point and held at that temperature, so that it becomes elastically deformed.
As a result, it acts as a spring, and the sixth
As shown in the figure, the pulley 4 is rotated to the left, that is, in the direction in which the throttle valve 3 is closed, so that the contact pin 4a comes into contact with the right side edge of the throttle lever 15. Alternatively, when the position of the throttle lever 15, that is, the amount of depression of the accelerator pedal is less than the throttle valve fully closed opening degree (from F to G in Fig. 5b), the pulley 4 stops at the throttle valve fully closed position. ,
The contact pin 4a does not contact the right edge of the throttle lever 15.

Next, in this state, when the accelerator pedal 8 is depressed as shown in steps 1 → 2 → 5 in FIG. 4, the throttle lever 15 undergoes a play of an angle θ, and then its right edge contacts as shown in FIG. 7. in contact with pin 4a,
Change the throttle valve opening as follows: 2←→3. That is, the throttle valve 3 is mechanically connected to the accelerator pedal 8, and opens and closes in accordance with the movement of the accelerator pedal 8. Therefore, even when the actuator 5 fails, manual control is possible.

The operation of the throttle valve control device of the present invention has been described above. In the throttle valve control device of the present invention, the throttle valve return spring 14 does not act on the throttle valve 3 as a spring when the actuator 5 is normal. ,
The load placed on the actuator 5 can be extremely small. Therefore, the actuator 5 can be miniaturized, the space occupied by the device can be reduced, and the operating speed of the actuator 5 can be increased to improve controllability.

Note that the throttle valve control device of the present invention is not limited to the above-mentioned embodiments, and may include, for example, one in which the actuator 5 and the throttle shaft 2 are directly connected as shown in FIG. The driving force transmission part between the shaft 2 and the shaft 2 is composed of gears, the actuator 5 is hydraulic or pneumatic, and the heating to the throttle valve return spring 14 is controlled by PTC (Positive Temperature Coefficient).
It may also be carried out using a heater. Further, as shown in FIGS. 6 and 7, guides 19, 20, which guide the throttle valve return spring 14,
21 may be provided, and in this case, there is an effect that it is possible to prevent the return spring 14 from elongating more than necessary or from cracking due to vibration during plastic deformation.

〔Effect of the invention〕

As mentioned above, the throttle valve control device according to the present invention has extremely important practical advantages in that the space occupied by the device is small and the controllability is good.

[Brief explanation of the drawing]

Fig. 1 is an overall view of an embodiment of a throttle valve control device according to the present invention, Fig. 2 is a side view of essential parts showing the positional relationship between the right side edge of the throttle lever and the contact pin in the above embodiment, and Fig. 3 and fourth
The figures are graphs showing linear and non-linear changes in the throttle valve opening with respect to the accelerator pedal depression amount when the actuator is normal.
Figures a and b are graphs showing the influence of the transient characteristics of the actuator when the throttle lever moves quickly and slowly, respectively. FIG. 8 is a partially cutaway plan view of another embodiment, showing the action and action of the mechanical control means. 1...Intake cylinder, 2...Throttle shaft, 3
...Throttle valve, 4...Pulley, 4a...
... Contact pin, 5... Actuator, 6...
... Belt, 7 ... Tensioner, 8 ... Accelerator pedal, 9 ... Accelerator pedal depression amount sensor, 10 ... Speed sensor, 11 ... Command switch, 12 ... Electronic control circuit, 13 ... Return spring energization circuit, 14... Throttle valve return spring, 15... Throttle lever,
16... Accelerator wire, 17... Damper, 1
8...Accelerator return spring, 19,2
0,21...Guide.

Claims (1)

[Claims] 1 Equipped with an actuator that controls the opening degree of the throttle valve according to the movement of the accelerator pedal and the operating state of the engine, and when the actuator fails, the throttle valve is returned to the fully closed position by the action of a return spring. In an engine throttle valve control device in which an accelerator pedal and a throttle valve are mechanically connected, the return spring is formed from a shape memory alloy that deforms plastically when the temperature is below the transformation point and deforms elastically when the temperature is above the transformation point. A throttle valve control device characterized in that, when the actuator fails, the return spring is maintained at a temperature above the transformation point.