Throttle valve system for internal combustion engine

Details Throttle valve system for internal combustion engine Throttle valve system for internal combustion engine

2003-08-27

2004-11-09

Lo, Weilun (Department: 3747)

Internal-combustion engines

Engine speed regulator

Specific throttle valve structure

C251S305000

Reexamination Certificate

active

06814051

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2002-250438 filed on Aug. 29, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a throttle valve system of an internal combustion engine capable of preventing freezing of a throttle valve. More specifically, the invention relates to the throttle valve system having a function for preventing the freezing of the throttle valve, which is caused by water coming along an inner peripheral surface of an intake pipe from an upstream side of the throttle valve during a cold period such as a winter season. The present invention also relates to downsizing of a bore portion of a throttle body, in which the throttle valve is accommodated and held rotatably.
2. Description of Related Art
In a cold period such as a winter season, PCV water enters a bore portion
102
of a throttle body from an upstream side of a throttle valve
101
along an inner peripheral surface of an intake pipe and is trapped at a blocked position of the throttle valve
101
as shown in FIG.
13
. Then, the PCV water is frozen there. The PCV water is, for example, water flowing from a positive crankcase ventilation system into the intake pipe through an outlet port located upstream of the throttle valve
101
. As a result, malfunction of an internal combustion engine may be caused. Therefore, a throttle valve system for overcoming such a problem has been proposed.
For instance, in a throttle valve system disclosed in Japanese Patent Unexamined Publication No. H09-32590 (Pages 3 to 5, FIGS.
1
and
2
), a bore portion
202
of a throttle body has double-tube structure, in which an inner bore tube
212
and an outer bore tube
211
are integrally formed of heat-resistant resin, as shown in FIG.
14
. The inner bore tube
212
is formed inside the outer bore tube
211
concentrically with the outer bore tube
211
. A longitudinal length of the inner bore tube
212
in a direction of intake-air flow is a little shorter than that of the outer bore tube
211
. The inner bore tube
212
forms an intake air passage
203
. A throttle valve
201
is installed through a shaft at the middle of the longitudinal length of the inner bore tube
212
. An annular disk-like partition wall
204
is disposed between the outer bore tube
211
and the inner bore tube
212
through an entire circumference nearly at the middle of the longitudinal length of the inner bore tube
212
in a flat plane perpendicular to the intake-air flow direction. Thus, the partition wall
204
divides an annular space formed between the outer bore tube
211
and the inner bore tube
212
into upstream and downstream trapping concavities (water trapping grooves)
221
,
222
for trapping the upstream PCV water flowing into the outer bore tube
211
of the throttle body along the inner peripheral surface of the intake pipe.
As explained above, in the conventional throttle valve system shown in
FIG. 14
, the central axis of the outer bore tube
211
is arranged concentrically with the central axis of the inner bore tube
212
. Furthermore, the annular space between the outer bore tube
211
and the inner bore tube
212
is separated by the annular disk-like partition wall
204
through the entire circumference. Therefore, the trapping concavities
221
,
222
are provided with uniform radial width throughout the circumference. Consequently, there arises such a problem that the radial size of the bore portion
202
of the throttle body increases, so the bore portion
202
is upsized.
In addition, a flowing pattern or flowing quantity of the water flowing from the upstream side or the downstream side of the throttle valve varies in accordance with a layout of an intake system of a vehicle, a mounting position of an idling speed control valve (ISC valve), and a mounting position of the throttle body to the vehicle. The ISC valve is used for controlling the idling rotation speed of the engine by regulating the quantity of air flowing through a bypass of the throttle valve. Therefore, trapping concavities having required size should be preferably provided in optimum positions in accordance with the flowing condition of the water flowing into the throttle body.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a throttle valve system of an internal combustion engine capable of providing a space, an annular space or a trapping concavity having a required size at an optimum position in accordance with flowing condition of water flowing into a throttle body. It is therefore another object of the present invention to provide a throttle valve system of an internal combustion engine capable of preventing freezing of the throttle valve without introducing engine cooling water, while downsizing the throttle body.
According to an aspect of the present invention, a throttle body has double-tube structure, in which an outer bore tube radially surrounds an outer peripheral surface of an inner bore tube. The inner bore tube accommodates a throttle valve so. that the throttle valve can open or close. The double-tube structure is formed so that a radial distance between the inner bore tube and the outer bore tube at a certain position differs from the radial distance between the inner bore tube and the outer bore-tube at another position. A space formed, between the outer periphery of the inner bore tube and the inner periphery of the outer bore tube is located in a required size at an optimum position in accordance with flowing condition of water entering the throttle body. Thus, the water can be surely trapped in the space even if a flowing pattern or flowing quantity of the water flowing in from an upstream side or a downstream side of the throttle valve changes due to a change in a layout of an intake system of a vehicle, a mounting position of an ISC valve, or a mounting position of the throttle body to the vehicle. As a result, freezing of the throttle valve can be prevented without introducing engine cooling water.
According to another aspect of the present invention, the throttle body is formed in the double-tube structure, in which the inner bore tube is formed in the outer bore tube so that the central axis of the inner bore tube is deviated from the central axis of the outer bore tube. Thus, the radial size of the throttle body is reduced, so the throttle body is downsized.


REFERENCES:
patent: 5704335 (1998-01-01), Akutagawa et al.
patent: 6408817 (2002-06-01), Torii et al.
patent: 2004/0041117 (2004-03-01), Suzuki

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