JPH11210502A - Throttle body for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent return blow-by gas from a crankcase, contained in intake air, from leaking outside through a lip part of an oil seal due to the intake pulsation of an engine. SOLUTION: A main body 1 of a throttle body is provided with an inclined communicating hole 6 with one opening end 6a positioned close to a clearance between a throttle shaft 3 and an inner ring 42 of a sealed bearing 4 and with the other opening end 6b positioned downstream of the totally closed position of a throttle valve 5 of an intake passage internal wall 2a. The partial flow of blow-by gas that is about to pass through the clearance between the throttle shaft 3 and the inner ring 42 is deflected to pass through the inclined communicating hole 6, and is sucked into an intake passage 2 by intake pipe negative pressure. Blow-by gas leaking to the outside from a lip part 7a of an oil seal 7 can therefore be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle body for controlling an intake air amount of an internal combustion engine, and more particularly to an improvement of a throttle shaft bearing.

[0002]

2. Description of the Related Art Conventionally, as a bearing structure of a throttle shaft of a throttle body, FIGS.
As shown in (b), it is common to use a sealed bearing 4 for smooth operation and ensuring dustproofness. The outer peripheral surface 41a of the outer ring 41 is fitted into the bearing hole 101a of the throttle body 101, and the inner peripheral surface 42a of the inner ring 42 is loosely fitted to the bearing portion of the throttle shaft 3 with a slight clearance. Rubber seals 44 are provided on the outer race 41 on both sides of the ball 43 to prevent grease for lubrication from flowing out and foreign matter from entering from outside. Further, an oil seal 7 is provided outside (atmospheric side) of the sealed bearing 4 to maintain the airtightness between the intake passage 2 and the outside, and a retainer 8 is provided coaxially with the oil seal 7. That is, the outer peripheral surface 8a and the inner peripheral surface 8b of the retainer 8 are respectively connected to the throttle body main body 101.
Of the oil seal 7 and the outer peripheral surface 7b of the oil seal 7. A lip portion 7a is formed on the inner peripheral portion of the oil seal 7, and elastically contacts the surface of the throttle shaft 3 to maintain airtightness.

[0003]

However, even if the air-tightness is maintained by the oil seal 7 or the like, the intake air in the intake passage 2 is not removed from the crankcase by the pulsation of the intake air of the engine. Along with the blow-by gas flowing upstream of the main body 101, the gas leaks to the outside through the lip portion 7a of the oil seal 7 via the gap between the inner ring 42 of the sealed bearing 4 and the throttle shaft 3. Accordingly, the present invention provides a throttle body for an internal combustion engine that can significantly reduce the leakage of blow-by gas contained in intake air to the outside.

[0004]

According to a first aspect of the present invention, there is provided a throttle shaft provided rotatably across an intake passage of a main body, and a throttle shaft for controlling an intake air amount. It is mainly composed of a throttle valve fixed to the throttle shaft, a sealed bearing provided to support the throttle shaft, and an oil seal provided outside the sealed bearing to maintain airtightness. In a throttle body of an internal combustion engine, a slope having one open end near a gap between the inner ring of the sealed bearing and the throttle shaft and the other open end at a position downstream of the throttle valve fully closed position on a wall surface of the intake passage. The communication hole is provided in the main body.

The invention according to claim 2 is characterized in that the inner diameter of the inclined communication hole is 0.5 to 1.0 mm, and the inclination angle θ is 30 to 60 degrees from horizontal.

[0006]

As described above, according to the first aspect of the present invention, one open end is located near the gap between the inner ring of the sealed bearing and the throttle shaft, and the other open end is located at the throttle valve fully closed position on the intake passage wall surface. The inclined communication holes respectively provided at the downstream positions deflect and allow a part of the flow of the blow-by gas, which is going to flow into the gap between the inner ring and the throttle shaft, to pass through by the intake pipe negative pressure downstream of the throttle valve. Then, a part of the blow-by gas is sucked into the intake passage. Therefore, the amount of blow-by gas leaking outside from the gap between the lip portion of the oil seal and the throttle shaft is suppressed. According to the second aspect of the invention, when the inner diameter of the inclined communication hole is within an appropriate numerical range, the amount of blow-by gas passing through the inclined communication hole can be regulated.
Also, if the inclination angle of the inclined communication hole is within the appropriate numerical range,
The blow-by gas flowing in the inclined communication hole can flow without stagnation along the inclination of the communication hole.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a longitudinal sectional view of a throttle body according to the present invention, and FIG. 1B is an enlarged sectional view of a bearing portion thereof. A throttle shaft 3 is axially supported by a sealed bearing 4 across the intake passage 2 at the center of the throttle body 1, and a throttle valve 5 is fixed to an intake passage portion of the throttle shaft 3. Sealed bearing 4
The outer circumference 41a of the outer ring 41 is fitted into a bearing hole 1a of the throttle body 1, and the throttle shaft 3 is loosely fitted in the inner ring 42 with a small gap. The sealed bearing 4 has rubber seals 44 on both sides of which a metal ring is baked with nitrile rubber in order to secure dustproofness and hold grease for lubricating the balls 43. An oil seal 7 is fitted to the outside (atmosphere side) of the sealed bearing 4 by a retainer 8 provided coaxially with the oil seal 7. That is, the outer peripheral surface 8a of the retainer 8 is press-fitted into the retainer press-fit hole 1b of the throttle body 1, and
The inner peripheral surface 8 b of the retainer 8 has an outer peripheral surface 7 of the oil seal 7.
b is press-fitted. A lip 7a is formed on the throttle shaft 3 side of the oil seal 7, and the oil seal 7 is elastically contacted with the throttle shaft 3 to maintain airtightness.

One opening end 6a is provided inside the sealed bearing 4 (on the side of the intake passage) near the gap between the inner ring 42 and the throttle shaft 3, and the throttle valve 5 on the inner wall 2a of the intake passage.
An inclined communication hole 6 having the other open end 6b is provided in the throttle body 1 downstream of the fully closed position. The inner diameter of the inclined communication hole 6 is 0.5 to 1.0 mm, and the inclination angle θ is 30 degrees from the horizontal plane (mounting surface) 1c in the figure.
It is drilled at ~ 60 degrees. In this embodiment, the inclined communication hole 6 is provided only on the side where one end of the throttle shaft 3 is open to the outside, and the other end is surrounded by the room 9 and is not open to the outside. Although not provided, the same configuration may be adopted when the tip is opened to the outside.

Next, the operation of this embodiment will be described.
As described above, one open end 6a is provided on the inner side of the sealed bearing 4 (on the side of the intake passage) near the gap between the inner ring 42 and the throttle shaft 3, and the downstream end of the intake valve inner wall 2a from the fully closed position of the throttle valve 5. The inclined communication holes 6 each having the other open end 6b are provided with a part of the blow-by gas which is going to go outside through the gap between the inner ring 42 and the throttle shaft 3 by the negative pressure of the intake pipe downstream of the throttle valve 5. The flow is deflected and passed. Then, a part of the blow-by gas is sucked into the intake passage 2. Therefore, leakage of the blow-by gas to the outside is suppressed.

When the inner diameter of the inclined communication hole 6 is less than 0.5 mm, no pressure acts to deflect the flow of the blow-by gas to be discharged to the outside, and there is no effect of sucking the blow-by gas. Due to the small diameter, clogging is likely to occur due to blow-by gas, and workability such as drill breakage is also lacking.
If it exceeds 1.0 mm, when the throttle valve 5 is fully closed, leakage of intake air from the bearing portion of the throttle shaft 3 that bypasses the throttle valve 5 increases, the degree of sealing of the throttle valve 5 decreases, and idle air is reduced. Variations in the amount cause difficulty in idle control. When the inclination angle θ of the inclined communication hole 6 is less than 30 degrees, the oil mist contained in the blow-by gas passing through the inclined communication hole 6 is unlikely to flow into the intake passage 2, and Adhesion causes clogging. The tilt angle θ is 60
If it exceeds the degree, the workability of the inclined communication hole 6 will be reduced.

[0011]

As described above, the present invention has the following advantages. In other words, according to the throttle body of the first aspect, the blow-by gas which is about to flow into the gap between the inner ring and the throttle shaft through the inclined communication hole is partially deflected by the intake pipe negative pressure, and the intake passage is deflected. As a result, the amount of blow-by gas leaking from the gap between the lip portion of the oil seal and the throttle shaft can be reduced. According to the throttle body of the second aspect, since the inner diameter and the inclination angle of the inclined communication hole are set within appropriate numerical ranges, the amount of blow-by gas flowing through the inclined communication hole can be regulated. Since the blow-by gas flows through the inclined communication holes without stagnation, no clogging occurs. Further, there is no decrease in workability.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of a throttle body according to an embodiment of the present invention. FIG. 1B is an enlarged view of a bearing portion according to one embodiment of the present invention.

FIG. 2A is a longitudinal sectional view of a throttle body showing a conventional technique. FIG. 2B is an enlarged view of a bearing portion showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throttle body main body 2 Intake passage 2a Intake passage inner wall 3 Throttle shaft 4 Sealed bearing 5 Throttle valve 6 Inclined communication hole 6a Open end 6b Open end 42 Inner ring

Claims (2)

[Claims] 1. A throttle shaft rotatably provided across an intake passage of a main body, a throttle valve fixed to the throttle shaft for controlling an intake air amount, and a shaft for supporting the throttle shaft. In a throttle body of an internal combustion engine mainly composed of a sealed bearing provided and an oil seal provided outside the sealed bearing to maintain airtightness, one opening end has an inner ring of the sealed bearing and the throttle. A throttle body for an internal combustion engine, wherein an inclined communication hole having the other open end at a position downstream of the throttle valve fully closed position on the wall surface of the intake passage is provided near the gap between the shafts. 2. The inner diameter of the inclined communication hole is 0.5 to 1.0.
2. The throttle body for an internal combustion engine according to claim 1, wherein the inclination angle is 30 to 60 degrees from horizontal.