JPH09303163A - Throttle device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a leak air flow of a throttle valve as icing is prevented from occurring. SOLUTION: A spherical wall surface 11 curved along the locus of an upper stream inclination outer peripheral edge part 21 is formed in a throttle chamber 1 in such a state to be connected to an upper stream opposite stepped part 10. A downstream opposite stepped part 12 making contact with a downstream inclination outer peripheral edge part 22 during closing of a throttle valve 2 is formed and a cylindrical wall surface 13 connected to the downstream opposite stepped part 12 and extending to a spot situated downstream of an intake passage 3 is formed.

Description

Detailed Description of the Invention

The present invention relates to an improvement in an engine throttle device.

[0002]

2. Description of the Related Art In order to properly perform feedback control of an idle speed of an engine to a target value, it is necessary to reduce the amount of leaked air passing through a throttle valve.

As a conventional engine throttle device,
For example, there is one as shown in FIG. 5 (Japanese Patent Laid-Open No. 5-296).
067 publication).

Explaining this, the throttle chamber 1 is formed with a spherical wall surface 15 that curves along the locus of the outer peripheral edge portion 20 of the throttle valve 2.

During operation in which the throttle valve 2 is opened within a range of a predetermined angle or less, the gap between the outer peripheral edge portion 20 and the spherical wall surface 11 is kept constant.

Further, as a valve structure provided in a conventional exhaust brake device, there is, for example, one shown in FIG. 6 (see Japanese Utility Model Laid-Open No. 4-76947).

To explain this, the chamber 31
An upstream facing stepped portion 30 and a downstream side facing stepped portion 32 are formed on the outer peripheral edge portion 40 of the valve 32.

In the fully closed position, the valve 32 passes between the valve 32 and the chamber 31 because the outer peripheral edge portion 40 abuts on the upstream side facing step portion 30 and the downstream side facing step portion 32. Leakage displacement can be kept small.

[0009]

However, in the conventional throttle device shown in FIG. 5, since the outer peripheral edge portion 20 of the throttle valve 2 does not have a stepped portion, the throttle valve 2 is fully closed at the fully closed position. There is a problem in that the amount of leaked air passing between the throttle valve 2 and the throttle chamber 1 cannot be suppressed to a sufficiently small amount.

To cope with this, when the valve structure shown in FIG. 6 is applied to the throttle device to reduce the amount of leaked air, the upstream facing stepped portion 30 projects immediately downstream of the outer peripheral edge portion 40. Therefore, the ice formed by the solidification of the moisture in the air that expands through the gap between the outer peripheral edge portion 40 and the chamber 31 during cold weather adheres to the upstream side opposite step portion 30, and the valve 3
There is a possibility of causing icing which causes the opening and closing operation of No. 2 to be defective.

The present invention has been made in view of the above problems, and it is an object of the present invention to reduce a leaking air flow of a throttle valve while preventing icing in an engine throttle device.

[0012]

An engine throttle device according to a first aspect of the present invention is an engine throttle device including a throttle chamber defining an intake passage and a throttle valve rotatably interposed in the throttle chamber. In the throttle device, an outer peripheral edge portion of the throttle valve has an upstream inclined outer peripheral edge portion that inclines toward an upstream side of the intake passage and a downstream inclined outer peripheral edge portion that inclines toward a downstream side of the intake passage when the valve is opened. And a spherical wall curved in the throttle chamber along the locus of the upstream tilted outer peripheral edge portion, wherein the throttle chamber has an upstream facing step portion that abuts the upstream tilted outer peripheral edge portion when the throttle valve is closed. Is connected to the upstream facing step portion, and the downstream side pair that contacts the downstream tilted outer peripheral edge portion in the throttle chamber when the throttle valve is closed. Stepped portion is formed, and connected to a downstream side facing stepped portion in the throttle chamber to form a cylindrical wall extending on the downstream side of the intake passage.

According to a second aspect of the present invention, there is provided the engine throttle device according to the first aspect of the invention, wherein the throttle valve has a limit opening degree θ ₀ set so that icing does not easily occur, and at least the throttle valve opens the spherical wall to the limit. It is formed so as to face the upstream tilted outer peripheral edge portion in the operating range in which the valve is opened up to a degree θ ₀ .

According to a third aspect of the present invention, in the engine throttle apparatus according to the first or second aspect, a labyrinth groove is formed in the upstream tilted outer peripheral edge portion so as to face the spherical wall surface.

[0015]

In the engine throttle device according to the first aspect of the invention, in the fully closed position of the throttle valve, the upstream tilted outer peripheral edge portion abuts the upstream opposite stepped portion, and the downstream tilted outer peripheral edge portion. Since it comes into contact with the downstream facing step portion, the amount of leaked air passing between the throttle valve and the throttle chamber can be suppressed small.

During operation in which the upstream tilted outer peripheral edge of the throttle valve faces the spherical wall surface, the gap between the two is kept small, so the amount of air flowing through the gap between the two is kept small. As a result, during cold weather, the amount of ice that solidifies the moisture in the air during the process of expansion through the gap between the upstream tilted outer peripheral edge portion and the spherical wall surface is suppressed to a small amount, and the ice adheres to the upstream facing step portion. Icing can be prevented.

At this time, the gap between the downstream inclined outer peripheral edge portion and the cylindrical wall surface expands, and most of the air flows through the gap between the downstream inclined outer peripheral edge portion and the cylindrical wall surface. In cold weather, even if the moisture in the air that expands through the gap between the downstream tilted outer peripheral edge and the cylindrical wall surface solidifies, the intake flow is opposed to the vicinity of the downstream side of the downstream tilted outer peripheral edge in the intake passage. Since there is no protruding object, ice can be prevented from adhering to the wall surface of the throttle chamber and causing icing.

In the engine throttle device according to a second aspect of the present invention, during operation in which the throttle valve opens within a range of a maximum angle θ ₀ or less, the upstream tilted outer peripheral edge portion faces a spherical wall surface, and a gap between the two is formed. Since it is kept small, the amount of air flowing through the gap between the two is kept small. As a result, during cold weather, the amount of ice that solidifies the moisture in the air during the process of expansion through the gap between the upstream tilted outer peripheral edge portion and the spherical wall surface is suppressed to a small amount, and the ice adheres to the upstream facing step portion. Icing can be prevented.

During operation in which the throttle chamber is largely opened beyond the maximum angle θ ₀ , the upstream tilted outer peripheral edge portion is separated from the spherical wall surface, and the amount of air flowing around the upstream tilted outer peripheral edge portion increases, Since the differential pressure across the throttle valve decreases and water in the air passing through the throttle valve is less likely to solidify, it is possible to prevent ice from adhering to the upstream facing step portion and causing icing.

In the engine throttle device according to the third aspect of the present invention, during operation in which the upstream side tilted outer peripheral edge portion faces the spherical wall surface, in the middle of the gap defined between the upstream side tilted outer peripheral edge portion and the spherical wall surface. Since the cross-sectional area expands through the labyrinth groove, the pressure decreases gradually before and after the throttle valve, and the amount of air flowing through this gap can be suppressed to be small. As a result, in cold weather, the amount of ice that solidifies the moisture in the air during the process of expansion through the gap between the upstream inclined outer peripheral edge portion and the spherical wall surface is suppressed to a small amount, and the ice adheres to the upstream facing step portion. Icing can be prevented.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the intake passage 3 of the engine
A throttle valve 2 is provided in the. The intake passage 3 is
A throttle chamber 1 in which a throttle valve 2 is installed, a duct connected to an upstream side of the throttle chamber 1 to guide air taken in from an air cleaner (not shown), and a duct connected to a downstream side of the throttle chamber 1 to intake air for each cylinder. It is configured by an intake manifold or the like, which is not shown in the drawing.

The intake passage 3 is connected to a bypass passage (not shown) that bypasses the throttle valve 2 and guides intake air.
An auxiliary air amount control valve is installed in the middle of the bypass passage. During idle operation when the throttle valve 2 is in the fully closed position, the auxiliary air amount control valve is duty-controlled between 0 and 100% to adjust the intake air amount to target the idle speed of the engine. It is designed to feedback control the value.

The throttle valve 2 is rotatably provided via a shaft 9. The shaft 9 is adapted to rotate in conjunction with an accelerator pedal via a link mechanism (not shown) and a wire or the like. As the accelerator pedal is depressed, the throttle valve 2 rotates via the shaft 9 in the direction indicated by the arrow in the figure, increasing the intake air amount of the engine.

The throttle valve 2 is substantially orthogonal to the center line O ₂ of the intake passage 3 at the fully closed position as shown by the solid line.

The outer peripheral edge portion of the throttle valve 2 has an upstream tilted outer peripheral edge portion 21 that tilts toward the upstream side of the intake passage 3 and a downstream side that tilts toward the downstream side of the intake passage 3 when the valve opening operation is performed. It is divided into a tilted outer peripheral edge portion 22.

An upstream facing step portion 10 is formed in the throttle chamber 1 for contacting the upstream tilted outer peripheral edge portion 21 when the throttle valve 2 is closed. The upstream facing step portion 10 is formed in a plane shape orthogonal to the center line O ₃ of the intake passage 3. The upstream side facing step portion 10 is located below the shaft 9 in the figure and extends in a semi-annular shape.

As shown in FIG. 2, the throttle chamber 1 is formed with a spherical wall surface 11 that curves along the locus of the upstream tilted outer peripheral edge portion 21. The throttle valve 2 is formed in a disk shape, while the spherical wall surface 11 is curved in a spherical shape concentric with the shaft 9. The spherical wall surface 11 is connected to the upstream facing step portion 10 and extends.

The outer peripheral edge portion of the throttle valve may be formed in an oval shape, while the spherical wall surface of the throttle chamber may be formed in an oval cross section facing the outer peripheral edge portion with a certain gap.

The spherical wall surface 11 is formed so as to face the upstream-side tilted outer peripheral edge portion 21 within a range in which the throttle valve 2 rotates from the fully closed position to a predetermined maximum angle θ ₀ .

FIG. 3 shows the relationship between the opening of the throttle valve 2 and the differential pressure across the throttle valve 2. When the throttle valve 2 opens beyond the maximum angle θ ₀ , the differential pressure across the throttle valve 2 drops below a predetermined value P ₀ , making it difficult to cause icing. That is, the spherical wall surface 11 is formed to face the upstream-side tilted outer peripheral edge portion 21 at least within the opening range of the throttle valve 2 where icing is likely to occur.

The throttle chamber 1 is provided with a downstream facing stepped portion 12 which abuts the downstream tilted outer peripheral edge portion 22 when the throttle valve 2 is closed. The downstream facing step portion 12 is formed in a plane shape orthogonal to the center line O ₃ of the intake passage 3. The downstream facing step portion 12 is located above the shaft 9 in the figure and extends in a semi-annular shape.

The upstream side facing step portion 10 and the downstream side facing step portion 12
Face each other in parallel with a distance equal to the plate thickness of the throttle valve 2.

A cylindrical wall surface 1 which is connected to the downstream facing step portion 12 of the throttle chamber 1 and extends downstream of the intake passage 3.
3 is formed on the center line O ₃ and concentric cylindrical intake passage 3.

The configuration is as described above. Next, the operation will be described.

In the fully closed position of the throttle valve 2, the upstream tilted outer peripheral edge portion 21 has the upstream facing step portion 10.
And the downstream tilted outer peripheral edge portion 22 abuts on the downstream facing step portion 12, the throttle valve 2
The amount of leaked air passing between the throttle chamber 1 and the throttle chamber 1 can be reduced.

During idle operation when the throttle valve 2 is in the fully closed position, the amount of leaked air that passes through the throttle valve 2 is suppressed to a small value, so that the amount of auxiliary air that bypasses the throttle valve 2 via the auxiliary air amount control valve is reduced. It is sufficiently secured, and the idle speed of the engine can be appropriately feedback-controlled to the target value.

During operation in which the throttle valve 2 is opened within the range of the maximum angle θ ₀ or less, the gap between the upstream tilted outer peripheral edge portion 21 and the spherical wall surface 11 is kept constant, so that the upstream tilted outer peripheral edge portion 21 and The amount of air flowing through the gap of the spherical wall surface 11 is suppressed to be small. As a result, during cold weather, the amount of ice in which moisture in the air is solidified in the process of expanding through the gap between the upstream tilted outer peripheral edge portion 21 and the spherical wall surface 11 is suppressed to a small amount, and the ice is opposed to the upstream facing step portion. It is possible to prevent the icing from adhering to 10 and causing icing.

During operation in which the throttle valve 2 is opened within the range of the maximum angle θ ₀ or less, the gap between the downstream side tilted outer peripheral edge portion 22 and the cylindrical wall surface 13 is enlarged, and most of the air is in the downstream side tilted outer peripheral edge portion. It flows through the gap between 22 and the cylindrical wall 13. During cold weather, the downstream tilted outer peripheral edge portion 22 and the cylindrical wall surface 13
Even if the moisture in the air that expands through the gap is solidified, there is no protrusion facing the intake air flow in the vicinity of the downstream side of the downstream tilted outer peripheral edge portion 22 in the intake air passage 3, so that ice is not It is possible to prevent the icing from adhering to the.

During operation in which the throttle chamber 1 exceeds the maximum angle θ ₀ and opens widely, the upstream tilted outer peripheral edge portion 2
1 is separated from the spherical wall surface 11 and the amount of air flowing around the upstream tilted outer peripheral edge portion 21 increases, but the differential pressure across the throttle valve 2 decreases beyond a predetermined value P ₀ as shown in FIG. Therefore, water in the air passing through the throttle valve 2 is hard to be solidified, and ice can be prevented from adhering to the upstream facing step portion 10 and causing icing.

Next, the embodiment shown in FIG. 4 will be described. The parts corresponding to those in FIG. 1 are designated by the same reference numerals.

A labyrinth groove 23 is formed in the inclined outer peripheral edge portion 21 of the throttle valve 2 facing the spherical wall surface 11.

The labyrinth groove 23 has a rectangular cross section and is recessed. The labyrinth groove 23 is located below the shaft 9 in the figure and extends in a semi-annular shape.

In this case, during the operation in which the upstream tilted outer peripheral edge portion 21 faces the spherical wall surface 11 in the range where the throttle valve 2 is the maximum angle θ ₀ or less, the upstream tilted outer peripheral edge portion 21 and the spherical wall surface 11 have a space between them. Since the cross-sectional area is enlarged through the labyrinth groove 23 in the middle of the defined gap, the pressure is gradually reduced before and after the throttle valve 2, and the amount of air flowing through the gap can be suppressed to be small. As a result, during cold weather, the amount of ice in which water in the air is solidified in the process of expanding through the gap between the upstream tilted outer peripheral edge portion 21 and the spherical wall surface 11 is suppressed to a small amount, and the ice is opposed to the upstream facing step portion 10. It is possible to prevent the icing from adhering to the.

[0045]

As described above, according to the engine throttle device of the first aspect, in the fully closed position of the throttle valve, the upstream inclined outer peripheral edge portion abuts on the upstream opposed step portion. Since the downstream tilted outer peripheral edge portion abuts on the downstream side facing step portion, the amount of leaked air passing between the throttle valve and the throttle chamber can be suppressed to be small. In addition, when the throttle valve opening is small and the upstream tilted outer peripheral edge portion faces the spherical wall surface, the gap between the two is kept small, so ice adheres to the upstream facing step portion and icing occurs. Can be prevented.

According to the engine throttle device of the second aspect, during the operation in which the throttle chamber is largely opened beyond the maximum angle θ ₀ , the upstream side tilted outer peripheral edge portion is separated from the spherical wall surface, and the upstream side tilted outer peripheral part is formed. Although the amount of air flowing around the peripheral edge increases, the differential pressure across the throttle valve decreases and the moisture in the air passing through the throttle valve is less likely to solidify, so ice adheres to the upstream facing step. It is possible to prevent icing from occurring.

According to the third aspect of the engine throttle device, during the operation in which the upstream tilted outer peripheral edge portion faces the spherical wall surface, the gap defined between the upstream tilted outer peripheral edge portion and the spherical wall surface is formed. Since the cross-sectional area expands through the labyrinth groove on the way, the amount of air flowing through the gap between the upstream tilted outer peripheral edge and the spherical wall surface is suppressed to a small amount, and ice adheres to the upstream facing step and icing occurs. You can effectively prevent it from happening.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a throttle chamber and the like.

FIG. 3 is a characteristic diagram showing the relationship between the opening of the throttle valve and the differential pressure across the throttle valve.

FIG. 4 is a sectional view showing another embodiment.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is a sectional view showing still another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throttle chamber 2 Throttle valve 3 Intake passage 9 Shaft 10 Upstream opposing stepped portion 11 Spherical wall surface 12 Downstream opposing stepped portion 13 Cylindrical wall surface 21 Upstream tilted outer peripheral edge portion 22 Downstream tilted outer peripheral edge portion 23 Labyrinth groove

Claims (3)

[Claims] 1. A throttle device for an engine, comprising: a throttle chamber defining an intake passage; and a throttle valve rotatably interposed in the throttle chamber, wherein an outer peripheral edge portion of the throttle valve has an opening operation. Occasionally, it has an upstream tilted outer peripheral edge portion that tilts toward the upstream side of the intake passage and a downstream tilted outer peripheral edge portion that tilts toward the downstream side of the intake passage, and the upstream side when the throttle valve is closed in the throttle chamber. The throttle chamber is formed with an upstream facing stepped portion that abuts the tilted outer peripheral edge portion, and a spherical wall that curves along the trajectory of the upstream tilted outer circumferential edge portion is connected to the upstream facing stepped portion. When the throttle valve is closed, a downstream facing step portion that contacts the downstream tilted outer peripheral edge portion is formed, and the downstream facing step portion is connected to the throttle chamber. A throttle device for an engine, characterized in that a cylindrical wall surface which is in contact with and extends downstream of the intake passage is formed. 2. A set limits opening theta ₀ of the throttle valve icing does not occur easily, the spherical wall surface throttle valve least limit opening theta ₀
The throttle device for an engine according to claim 1, wherein the throttle device is formed so as to face the upstream tilted outer peripheral edge portion in the operating range in which the valve is opened up to. 3. The throttle device for an engine according to claim 1, wherein a labyrinth groove is formed on the upstream tilted outer peripheral edge portion so as to face the spherical wall surface.