Throttle unit of engine

Details Throttle unit of engine Throttle unit of engine

2001-09-12

2002-07-09

Dolinar, Andrew M. (Department: 3747)

Internal-combustion engines

Engine speed regulator

Having plural throttle valve structure

C123S585000

Reexamination Certificate

active

06415765

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a throttle unit having a reduced manufacturing cost and a reduced number of man hours for assembly. Furthermore, the present invention relates to a throttle unit which is suitable for equalizing the amount of air passing through the bypass passages of the throttle valves, a bypass passage being provided for each throttle valve.
2. Description of Background Art
A throttle unit for an engine has been disclosed in Japanese Patent No. 2723990 entitled “THROTTLE BODY FOR MULTIPLE-CYLINDER COMBUSTION ENGINE.” In the above document, a throttle unit is provided with a fast idling mechanism. The fast idling mechanism includes a valve for opening or closing a bypass passage for bypassing a throttle valve. The valve is provided in the bypass passage. Furthermore, when the engine is started, the valve is opened to supply air to the combustion chamber of the engine via the bypass passage to increase the number of revolution of the engine during idling to prevent the engine from unstably rotating during idling or stopping.
FIGS. 5 and 6
of the above document have been reproduced as
FIGS. 7 and 8
of the present invention, respectively. In addition, for the sake of convenience,
FIG. 7
of the present invention includes a portion of
FIG. 4
of the above document, and
FIG. 8
of the present invention includes a main portion of
FIG. 6
of the above document. Furthermore, the reference numerals in
FIGS. 7 and 8
of the present invention do not correspond to the reference numerals in the above document.
FIG. 7
is a first cross-sectional view of a throttle unit according to the background art which shows a state in which a throttle body
100
is provided with suction passages
101
,
102
, and in which the respective suction passages
101
,
102
are provided with throttle valves
103
, (not shown), respectively. Furthermore, the upstream side of the throttle valve
103
of one suction passage
101
is in communication with the downstream side of the throttle valve
103
of the suction passage
101
by a common bypass suction passage hole
105
and a bypass suction passage hole
106
for controlling the idling speed. The bypass suction passage hole
106
is connected to the common bypass suction passage
105
. Furthermore, an idling speed control valve
107
for opening or closing the bypass suction passage hole
106
is disposed at the inlet of the bypass suction passage hole
106
.
FIG. 8
is a second cross-sectional view of the throttle unit according to the background art.
FIG. 8
shows a state in which a bypass suction passage hole
108
for controlling the idling speed is branched from the common bypass suction passage hole
105
(see
FIG. 7
) and is in communication with the downstream side of the throttle valve (not shown) of the suction passage
102
. An idling speed control valve
111
for opening or closing the bypass suction passage hole
108
is disposed at the inlet of the bypass suction passage hole
108
. Operating levers
112
,
112
are secured to the end portions of the idling speed control valves
107
,
111
. Furthermore, a link shaft
113
for opening or closing the idling speed control valves
107
,
111
in one operation is mounted to the operating levers
112
,
112
.
According to the above-mentioned technology, idling speed control valves
107
,
111
are provided for each of the bypass suction passage holes
106
,
108
. Therefore, in addition to the idling speed control valves
107
,
111
, operating levers
112
,
112
and parts relating to these valves are required. This increases the number of parts and therefore the number of man hours for assembly and the manufacturing costs of the throttle unit are increased.
Furthermore, since the plurality of idling speed control valves
107
,
111
are opened or closed by one link shaft
113
via the operating levers
112
,
112
, depending on the variation in the size of the idling speed control valves
107
,
111
, the operating levers
112
, and the link shaft
113
, there is the possibility that a difference in the opening of the idling speed control valves
107
,
111
may be produced to make the amount of air passing through the respective bypass suction passage holes
106
different from the amount of air passing through the respective bypass suction passage holes
108
. Accordingly, the number of revolution of the engine during idling may become unstable.
SUMMARY OF THE INVENTION
For the above reason, the object of the present invention is to reduce the manufacturing costs and the number of man hours for assembly of the throttle unit of an engine and to equalize the amount of air passing through the bypass passages for each of the throttle valves.
In order to accomplish the object described above, according to a first aspect of the present invention, in a throttle unit of an engine including suction passages from an air cleaner to the respective combustion chambers of a multiple-cylinder engine, throttle valves disposed in the respective suction passages, and bypass passages bypassing the throttle valves, the bypass passage includes an inlet of the bypass passage communicating with the upstream side of the throttle valve of the suction passage, one valve body receiving chamber coaxial with the inlet of the bypass passage, a plurality of upstream side branch passages extending from the valve body receiving chamber, downstream side branch passages extending from the end portions of the upstream side branch passages and communicating with the downstream sides of the throttle valve of the suction passage, one valve body which is movably received in the valve body receiving chamber and is moved in the valve body receiving chamber in the direction away from the inlet of the bypass passage to open the plurality of upstream side branch passages at the same opening when opening the bypass passage.
In the throttle unit according to the background art, a bypass passage for bypassing a throttle valve is disposed in each suction passage sending air into the combustion chamber of each cylinder and a valve for opening or closing the bypass passage is disposed at each bypass passage and a link mechanism is disposed at each valve to activate the valve. For this reason, in the throttle unit according to the background art, the number of parts increases and the manufacturing cost and the number of man hours for assembly of the throttle unit increase. However, according to the-present invention, a mechanism for activating the bypass valve can be simplified by reducing the number of the bypass valves of the multiple-cylinder engine to one. This can reduce the manufacturing costs and the number of man hours required for assembly of the throttle unit.
Furthermore, during the control of the opening or closing of the bypass passage by one valve body in the throttle unit according to the background art, suction air tends to be sucked into one cylinder from the other cylinder by a difference in negative pressure between the respective cylinders. However, by controlling the opening of each of the plurality of upstream side branch passages to be at the same opening, it is possible to make the total sum of the opening areas of the upstream side branch passages smaller than the passage area of the inlet side of the bypass passage at a time when the number of revolutions of the engine is not more than 2000 rpm and tends to vary widely.
Accordingly, it is possible to prevent the suction air from being sucked into one cylinder from the other cylinder and therefore prevent a variation in the number of revolutions of the engine. Therefore, it is possible to control the number of revolutions of the engine during idling with a high accuracy.
According to a second aspect of the present invention, the plurality of upstream side branch passages are formed on a line crossing at right angles and passing through the valve body receiving chamber.
The plurality of upstream side branch passages can be easily formed in one machining step to reduce the time and cost of ma

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