JPH0532723Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a throttle valve opening sensor that detects the opening of a throttle valve of an internal combustion engine using a so-called potentiometer type.

<Prior Art> A conventional example of such a throttle valve opening sensor is disclosed in Japanese Utility Model Application No. 61-52213. Since the opening degree is transmitted to the sensor section through the opening, it is difficult to accurately detect the opening degree due to dimensional errors and the like. For this reason, consideration has been given to improving detection accuracy by providing a sensor section integrally with the throttle valve rotating shaft to eliminate the fitting section.

An example of the throttle valve opening sensor provided integrally with the throttle valve rotating shaft is shown in the second example.
As shown in FIG.

One end of a rotating shaft 3 of a throttle valve 2 installed in an intake passage 1 of an internal combustion engine is made to penetrate the peripheral wall of the intake passage 1 and protrude to the outside, and a brush is attached to the end of this protruding rotating shaft 3. A holder 5 is fixed integrally. This brush holder 5 is provided with a pair of brushes 4 electrically connected at different radial distances from the axis of the rotating shaft 3 at its tip.

On the other hand, a substrate 8 having a resistor 6 to which a power supply voltage is applied to the inner surface and an electrode plate 7 for taking out an output is inserted through a spacer 9 so as to cover the externally protruding portion of the rotating shaft 3. It is fixed to the outer wall of the intake passage 1. The resistor 6 and the electrode plate 7 are concentrically formed in an arc shape with different radii, and by fixing the substrate 8 with the center of this arc aligned with the axis of the rotating shaft 3, the brush 4 is fixed. Each of them is configured to slide in an arc shape on the resistor 6 and electrode plate 7 as the throttle valve 2 rotates.

According to this throttle valve opening sensor, when the throttle valve 2 rotates in conjunction with the accelerator pedal, the sliding contact position of the brush 4 with respect to the resistor 6 changes, so the resistance value of the resistor 6 changes, and the electrode plate Since the voltage taken out through the throttle valve 7 changes in accordance with the opening degree of the throttle valve 2, the opening degree of the throttle valve 2 can be detected by reading this output voltage change.

In addition, in this sensor, since the brush holder 5 is provided integrally with the rotating shaft 3 without a fitting part, the brush 4 linearly responds to changes in the opening degree of the throttle valve 2 and changes the resistance value of the resistor 6. This allows the throttle valve opening degree to be detected with high accuracy.

<Problems to be solved by the invention> By the way, if the brush holder 5 is provided integrally with the rotating shaft 3 as described above, the detection accuracy of the throttle valve opening degree can be improved, but Since the throttle valve 4 is sensitive to the movement of the rotating shaft 3, a change in output may occur that is not accompanied by a change in the opening of the throttle valve 2.

That is, for example, if the brush 4 is in sliding contact with the throttle valve 2 at the position shown in FIG. When deflected in the axial direction, the brush 4 moves along the axial direction of the intake passage 1 (in the direction of the arrow in the figure) due to this deflection. Such movement of the brush 4 is accompanied by movement of the brush 4 in the circumferential direction, which changes the resistance value of the resistor 6, and even if the throttle valve 2 remains fully closed, the detected value of the sensor will change. This will be output as a slight change in the opening degree of the throttle valve 2.

In particular, electronically controlled fuel that predicts the intake air flow rate of the engine based on the throttle valve opening and engine rotation speed detected using such a sensor, and controls the fuel injection amount based on the predicted intake air flow rate. In an injection device, if the output value (detected value) changes as described above even though the throttle valve opening is constant, fuel injection amount control is performed as if the intake air flow rate has changed.
However, since the intake air flow rate changes rapidly when the throttle valve starts to open from a fully closed state, if the detection accuracy near the fully closed throttle valve is unstable as described above, fuel injection amount control may be affected. The problem is that it has a large negative impact. Here, the mechanism by which the brush moves due to suction negative pressure will be explained in detail.

First, the suction negative pressure exceeds -600mmHg when the engine is decelerating or idling, and the diameter of the throttle valve varies depending on the engine, but in general, a diameter of around 50mm is often used. Therefore, the amount of deflection of the throttle shaft is calculated under these conditions.

In addition, the distance between the bearing axes L = 80 mm, the throttle shaft diameter d = 9 mm, the distance between the brush tip and the bearing L2 = 60 mm, and the material of the throttle shaft is iron with a Young's modulus E = 21000 (Fig. 2 reference).

The amount of deflection of the throttle shaft can be calculated as the beams at both free ends supported by bearings, and the deflection angle (angle of inclination) i of the shaft at the bearing portion can be calculated using the following formula.

i=W×1/2L×{L ² −(1/2L) ² }/6×E
×I×L In the above formula, I is the second moment of area, and I=
It is calculated as (π/64)×d ⁴ , and the load W is
(600mmHg/760mmHg) × (50 ² × π) / (4 × 100)
=15.5Kg. Substituting other numerical conditions into the above equation yields i=0.0525 (deg).

Therefore, the amount of movement Z of the brush end in the axial direction of the intake passage in the potentiometer type throttle sensor
is determined by the following formula.

Z=tan i×L2=0.049mm Therefore, in the conventional layout shown in FIG.
Assuming 45°, ΔZ=Z×sin45=0.032mm.

Here, if the dimension H from the axis of the throttle shaft to the brush position (rotating radius of the brush) is 25 mm, then the effect Δθ on the angular position of the brush due to ΔZ is as follows: Δθ=sin ^-1 (0.032/25)= It becomes 0.08deg.

Since the angle Δθ corresponds to a deviation of 4 to 5% when converted to the amount of intake air at idle, the throttle valve opening and rotation are affected by the bending of the throttle shaft due to the influence of negative intake pressure. The accuracy of predicting the amount of air based on the speed will deteriorate.

The present invention was developed in view of the above-mentioned problems, and aims to stabilize the accuracy of opening detection near the fully closed throttle valve, where the intake air flow rate changes rapidly, using an opening sensor integrated into the throttle valve rotating shaft. The purpose is to achieve this goal.

<Means for solving the problem> Therefore, in the present invention, when the throttle valve is in a fully closed state, the position of the brush in sliding contact with the resistor is a position along the axial direction of the intake passage from the axis of the throttle valve rotating shaft. It was configured as follows.

<Operation> With this configuration, even if the brush moves its position as the rotating shaft bends, the movement does not include the circumferential direction of the resistor. This is because the deflection of the rotating shaft due to negative suction pressure coincides with the axial direction of the intake passage, so if the sliding contact position of the brush is set as above when the throttle valve is fully closed, the movement of the brush will be due to the arc-shaped resistor. The movement is in the radial direction,
There is no movement in the circumferential direction. Therefore, even if the rotating shaft is bent, the resistance value of the resistor can be prevented from changing, and output changes that are not caused by changes in the throttle valve opening can be minimized.

<Example> An example of the present invention will be described below based on FIG. 1. Note that the same elements as in the conventional example shown in FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the figure, the brush 4 provided at the tip of a brush holder 5 that is integrally fixed to the end of the rotating shaft 3 of the throttle valve 2 includes a resistor 6 and a resistor 6 provided in an arc shape centered on the axis of the rotating shaft 3. They are in sliding contact with the electrode plate 7, and their sliding contact positions are changed according to the opening degree of the throttle valve 2. And electrode plate 7
The opening degree of the throttle valve 2 is detected by changing the voltage taken out through the brush 4 in accordance with the change in the resistance value of the resistor 6 depending on the sliding contact position of the brush 4.

By the way, the throttle valve 2 shown in the figure is in a fully closed state, and in this fully closed state, the brush 4 is
As shown in the figure, the axial center of the rotating shaft 3 comes into sliding contact with the resistor 6 at a position along the axial direction of the intake passage 1. That is, when the throttle valve 2 is fully closed, the brush holder 5 stands upright along the axial direction of the intake passage 1, but when the throttle valve 2 is opened, the brush holder 5 opens according to its opening degree. It is something that leans in one direction.

When the throttle valve 2 is fully closed as shown in the figure,
When the rotary shaft 3 is bent in the direction of one axis of the intake passage due to the influence of negative suction pressure, the brush 4 moves its sliding contact position in the direction of this bending (the direction of the arrow in the figure), but this moving direction is circular. Since this is the radial direction of the arc-shaped resistor 6, the resistance value of the resistor 6 is originally changed by sliding the brush 4 in the circumferential direction, so the brush 4 moves in the radial direction as described above. However, the change in the resistance value of the resistor 6 is slight. Therefore, when the throttle valve 2 is fully closed, the sensor output does not change even though the opening degree of the throttle valve 2 is constant.
The detection accuracy near the fully closed position can be improved.

For this reason, in an internal combustion engine that controls fuel injection by predicting the intake air flow rate based on the throttle valve opening degree and engine rotation speed detected by such a sensor, it is possible to set the predicted intake air flow rate near the fully closed throttle valve to the actual value. It can be approximated by
It is possible to control the fuel injection amount approximately in accordance with the true intake air flow rate near the fully closed throttle valve, where the intake air flow rate suddenly changes, and it is possible to improve the drivability of the engine in the idling operating state.

<Effects of the invention> As explained above, according to the invention, the accuracy of opening detection near the fully closed throttle valve, where the intake air flow rate changes rapidly, is improved in the opening sensor that detects the opening of the throttle valve. This has the effect of improving various controls of the engine based on the detected throttle valve opening.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an intake passage showing a throttle valve opening sensor according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views of an intake passage showing a conventional throttle valve opening sensor. 1...Intake passage, 2...Throttle valve, 3...
Rotating shaft, 4...Brush, 5...Brush holder,
6...Resistor.

Claims (1)

[Scope of utility model registration request] A brush holder is provided integrally with a rotating shaft of a throttle valve installed in an intake passage of an internal combustion engine and has a brush at its tip; A throttle valve opening sensor for an internal combustion engine, which has an arc-shaped resistor whose resistance value changes as the resistance changes, and which detects the throttle valve opening as the resistance value of the resistor. A throttle valve opening sensor for an internal combustion engine, characterized in that the sliding position of the brush with respect to the resistor in a closed state is a position along the axial direction of the intake passage from the axis of the rotating shaft.