Idle speed control apparatus in throttle body for single cylinder

A single idle air control passage (5) open toward a suction air passage (2a) downstream from a throttle valve (4), a starter passage (6) and an air screw passage (7) independently branched from an upstream side passage (5a) of the passage (5), an upstream side of passage (6) communicates with atmospheric air, a downstream side thereof communicates with the upstream passage (5a) of the idle air control passage (5), a start opening and closing valve (10) controlling an opening area of the passage is arranged in the starter passage (6), an upstream side of the passage (7) communicates with an atomospheric air, a downstream side communicates with the upstream side passage (5a) of the idle air control passage (5), and an air screw (11) controlling an opening area of the passage is screwed to the air screw passage.

TECHNICAL FIELD

The present invention relates to a throttle body used in a fuel injection apparatus which boosts fuel within a fuel tank by a fuel pump and supplies the boosted fuel to an engine via a fuel injection valve, and more particularly to a single throttle body used in a single cylinder engine and a control apparatus of an idle air supplied to the engine at an idle time of the engine.

BACKGROUND ART

The idle air supplied to the engine at the idle time of the engine is separated into a normal idle air supplied in a normal temperature region including a hot time, and a first idle air supplied in a low temperature region of an engine atmosphere temperature.

In other words, in the normal temperature region of the engine, a predetermined idling operation of the engine is executed by the normal idle air.

Further, in the low temperature region of the engine, the first idle air increased in comparison with the normal idle air is supplied at a start time of the engine, and a low temperature start (a first idling operation) of the engine is executed by a hither rotational speed in comparison with the idling operation.

The supply of the normal idle air and the supply of the first idle air are particularly executed by an idle speed control apparatus shown inFIG. 2.

A description will be given with reference to the drawing. Reference numeral20denotes a single throttle body connected to a single cylinder engine via a suction air pipe (not shown). A suction air passage21is provided through in an inner portion of the throttle body, and the suction air passage is controlled so as to be opened and closed by a throttle valve23attached to a throttle valve shaft22.

Reference numeral24denotes an air screw passage which bypasses the throttle valve23, has a downstream side open to an inner side of a suction air passage21ain a downstream side from the throttle valve23, and has an upstream side open to a suction air passage21bin an upstream side from the throttle valve23. An air flowing within the air screw passage24is controlled by rotating an air screw25to variably adjust an opening area of the air screw passage24.

In other words, the opening area of the air screw passage24can be reduced so as to reduce an amount of air flowing through the air screw passage24, by the air screw25being adjusted to move in a downward direction in the drawing, and the opening area of the air screw passage24can be increased so as to increase an amount of air flowing through the air screw passage24, by the air screw25being adjusted to move in an upward direction.

The air screw passage24mentioned above is used for controlling the normal idle air supplied to the engine in the normal temperature region including the hot time.

Reference numeral26denotes a starter passage which bypasses the throttle valve23, has a downstream side open to the inner side of the suction air passage21ain the downstream side from the throttle valve23, and has an upstream side open to the suction air passage21bin the upstream side from the throttle valve23. The starter passage26is provided separately from the air screw passage.

A start opening and closing valve28operated so as to be moved by a drive member27, in which a heat expansion and contraction material such as a wax or the like is sealed in an inner portion, variably adjusts an opening area of the starter passage26, whereby an air flowing within the starter passage26is controlled.

In other words, in a low temperature state in which the engine atmosphere temperature is equal to or less than a fixed temperature, the heat expansion and contraction material reduces its volume, an operation lever27aof the drive member27moves to a lower side in the drawing, and the start opening and closing valve28moves to a lower side in synchronous therewith so as to increase the opening area of the starter passage26.

Accordingly, in addition to the normal idle air supplied from the air screw passage24, the first idle air is supplied toward the suction air passage21ain the downstream side from the throttle valve23from the starter passage26, whereby it is possible to execute an engine start (a first idling operation) in the low temperature state.

On the other hand, in a high temperature state in which the engine atmosphere temperature is higher than the fixed temperature, the heat expansion and contraction material expands its volume, the operation lever27aof the drive member27moves to an upper side in the drawing, and the start opening and closing valve28moves to an upper side in synchronous therewith so as to close the starter passage26.

In accordance with the structure mentioned above, the first idle air is not supplied into the suction air passage21ain the downstream side from the throttle valve23from the starter passage26, but the normal idle air is supplied to the suction air passage21ain the downstream side from the throttle valve23from the air screw passage24, whereby the engine start in the higher temperature state than the fixed temperature is executed.

In other words, in the case that the engine atmosphere temperature is in the normal temperature region including the hot time, the engine start and the idle operation are executed by the normal idle air supplied from the air screw passage24. On the other hand, in the low temperature region of the engine, the engine start and a thereafter warm-up operation are executed by the increased air obtained by adding the first idle air supplied from the starter passage26to the normal idle air supplied from the air screw passage24.

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

In accordance with the conventional idle speed control apparatus mentioned above, since all the passages constructing the starter passage26and the air screw passage24(corresponding to the upstream and downstream passages separated by the start opening and closing valve28and the air screw25) are independently formed, a freedom of passage design is low, and it is impossible to reduce a working man hour.

Further, since the starter passage26and the air screw passage24are open to the suction air passage21ain the downstream side from the throttle valve23, air flow is always generated during the engine operation in the air screw passage24, however, air flow is shut off in a state in which the engine atmosphere temperature is increased to a level equal to or more than the fixed value during the engine operation in the starter passage26.

On the other hand, during the engine operation, there is a case that a part of the fuel injected into the suction air passage21ain the downstream side from the fuel injection valve (not shown) is blown back in a direction of the suction air passage21bin the upstream side by the engine, and there is a case that the blown-back fuel goes into the starter passage26having no air flow so as to stay.

This matter significantly appears particularly at a time when the opening to the suction air passage21aof the starter passage26is open to a lower side in a gravitational direction.

Further, if the fuel staying in the starter passage26is sucked out to the suction air passage21ain a state of being accumulated to some extent, there is a case that a concentration of an air-fuel mixture directed to the engine is temporarily changed, causing a rotation fluctuation particularly at the engine idling operation time when the amount of the suction air is less in comparison with the other operation regions.

Further, it is impossible to form a start opening and closing valve guide tube28aslidably supporting the start opening and closing valve28and an air screw thread hole25afor screwing the air screw25on the same section and in parallel toward the same direction.

This is because the downstream side starter passage26aand the downstream side air screw passage24aare independently formed.

In accordance with the structure mentioned above, it is impossible to improve an assembling property of the drive member27including the air screw25and the start opening and closing valve28.

An idle speed control apparatus in a throttle body for a single cylinder in accordance with the present invention is made by taking the problem mentioned above into consideration, and an object of the present invention is to inhibit a matter that blown back fuel stays in an air screw passage and a starter passage and a concentration of an air-fuel mixture becomes temporarily rich even if fuel injected into a suction air passage from a fuel injection valve reaches the passages due to the blown-back, and to particularly inhibit a rotation fluctuation at an engine idling operation.

Further, another object is to improve a freedom of a passage design of the air screw passage and the starter passage, and to improve an assembling property and a maintenance property of a start opening and closing valve including an air screw and a drive member arranged in the passages.

[Means for Solving the Problem]

In order to achieve the object mentioned above, in accordance with a first aspect of the present invention, there is provided an idle speed control apparatus in a throttle body for a single cylinder, comprising:

a throttle body in which a suction air passage is provided through in an inner portion and the suction air passage is opened and closed by a throttle valve attached to a throttle valve shaft,

wherein a single idle air control passage is open toward a suction air passage in a downstream side from the throttle valve, a starter passage and an air screw passage directed to a suction air passage in an upstream side from the throttle valve are independently branched from an upstream side passage of the idle air control passage, a start opening and closing valve controlling an opening area of the starter passage by a drive member is arranged in the starter passage, and an air screw controlling an opening area of the air screw passage is arranged in the air screw passage.

Further, in accordance with a second aspect of the present invention, in addition to the first aspect mentioned above, a start opening and closing valve guide tube slidably guiding the start opening and closing valve is continuously provided in the starter passage, an air screw thread hole for screwing the air screw is continuously provided in the air screw passage, and a longitudinal axis of the start opening and closing valve guide tube and a longitudinal axis of the air screw thread hole are set in parallel and are open toward the same direction.

[Effect of the Invention]

In accordance with the first aspect of the present invention, the opening area of the air screw passage is controlled by rotating the air screw, the normal idle air is controlled, and the normal idle air is supplied to the suction air passage in the downstream side from the throttle valve from the idle air control passage.

On the other hand, in the low temperature region in which the engine atmosphere temperature is equal to or less than the fixed temperature, the start opening and closing valve releases the starter passage by the drive member so as to control first idle air, and the first idle air is supplied to the suction air passage in the downstream side from the throttle valve via the idle air control passage.

In this case, since the downstream side passage of the idle air control passage is open to the suction air passage in the downstream side from the throttle valve, and the air screw passage and the starter passage communicate with and are open to the upstream side passage of the idle air control passage, it is possible to continuously flow the normal idle air toward the downstream side passage from the upstream side passage of the idle air control passage even if the start opening and closing valve closes the starter passage, during the engine operation.

In accordance with the structure mentioned above, even if the fuel reaches the opening of the downstream side passage of the idle air control passage due to the blow-back of the engine, the normal air flow is generated toward the suction air passage from the downstream side passage. Accordingly, the blown-back fuel neither enters into the idle air control passage nor stay there, whereby the rotation fluctuation at a time of the engine idling operation is not generated.

Further, since the idle air control passage is formed open toward the suction air passage in the downstream side from the throttle valve, and the starter passage and the air screw passage are open to the idle air control passage, it is sufficient that only the single idle air control passage is open to the downstream side suction air passage. Accordingly, the passage structure becomes simple, and it is possible to improve a freedom of the passage design.

Further, in accordance with the second aspect of the present invention, since the starter passage and the air screw passage are independently branched from the idle air control passage, it is possible to set the respective longitudinal axes of the start opening and closing valve guide tube and the air screw hole in parallel and make them open toward the same direction.

In accordance with the structure, since it is possible to work the start opening and closing valve guide tube and the air screw thread hole from the same direction, it is possible to improve a working property thereof.

Further, it is possible to assemble the start opening and closing valve including the drive member and the air screw from the same direction, and it is possible to improve an assembling property and a maintenance property.

[Best Mode for Carrying out the Invention]

A description will be given below of an embodiment of an idle speed control apparatus in a throttle body for a single cylinder in accordance with the present invention with reference toFIG. 1.

Reference numeral1denotes a single throttle body connected to a single cylinder engine via a suction air pipe (not shown). A suction air passage2is provided through in an inner portion of the throttle body, and the suction air passage is controlled so as to be opened and closed by a throttle valve4attached to a throttle valve shaft3rotatably supported to the throttle body1.

Reference numeral5denotes a single idle air control passage open toward a suction air passage2ain a downstream side from the throttle valve4. A starter passage6is formed so as to be branched toward a suction air passage2bin an upstream side from the throttle valve4, and an air screw passage7is formed so as to be branched toward the suction air passage2bin the upstream side of the throttle valve4, from an upstream side passage5aof the idle air control passage5.

In other words, downstream sides of the starter passage6and the air screw passage7are connected and open to the upstream side passage5aof the idle air control passage5.

In this case, upstream sides of the starter passage6and the air screw passage7are open toward an atmospheric air.

A start opening and closing guide tube8is formed in the starter passage6so as to be directed toward an upper side in the drawing, an upstream side starter passage6aconnected to the suction air passage2bin the upstream side from the throttle valve4is open to a side wall of the start opening and closing valve guide tube8, and a downstream side starter passage6bconnected to the upstream side passage5aof the idle air control passage5is open to a bottom portion of the start opening and closing valve guide tube8.

Further, a guide hole9aand an air screw thread hole9are formed in the air screw passage7so as to be directed to an upper side in the drawing, an upstream side air screw passage7aconnected to the suction air passage2bin the upstream side from the throttle valve4is open to a side wall of the guide hole9a, and a downstream side air screw passage7bconnected to the upstream side passage5aof the idle air control passage5is open to a bottom portion of the guide hole9a. In other words, the starter passage6is formed by the upstream side starter passage6a, the start opening and closing valve guide tube8and the downstream side starter passage6b, an upstream side of the upstream side starter passage6ais open to the suction air passage2bin the upstream side from the throttle valve4, and a downstream side thereof is open to the side wall of the start opening and closing valve guide tube8.

Further, an upstream side of the downstream side starter passage6bis open to the bottom portion of the start opening and closing valve guide tube8, and a downstream side thereof is open to the upstream side passage5aof the idle air control passage5.

On the other hand, the air screw passage7is formed by the upstream side air screw passage7a, the air screw thread hole9including the guide hole9a, and the downstream side air screw passage7b, and an upstream side of the upstream side air screw passage7ais open to the suction air passage2bin the upstream side from the throttle valve4, a downstream side thereof is open to the side wall of the guide hole9a, and an upstream side of the downstream side air screw passage7bis open to the bottom portion of the guide hole9a, and a downstream side thereof is open to the upstream side passage5aof the idle air control passage5.

A start opening and closing valve10operated so as to be moved by a drive member W such as a wax, a stepping motor or the like is slidably arranged within the start opening and closing valve guide tube8of the starter passage6.

The drive member W is structured such that an output lever Wa is moved forward and backward in a vertical direction in the drawing by detecting an engine temperature and an engine atmosphere temperature. In the case that the engine atmosphere temperature is equal to or more than a fixed temperature, the output lever Wa is extended in a downward direction, and the start opening and closing valve10is moved downward in synchronous with the output lever Wa, and closes the upstream side starter passage6aopen to the start opening and closing valve guide tube8.

On the other hand, in the case that the engine atmosphere temperature is equal to or more than the fixed temperature, the output lever Wa is contracted in an upward direction, and the start opening and closing valve10is moved upward in synchronous with the output lever Wa, and opens the upstream side starter passage6atoward the start opening and closing valve guide tube8.

An air screw11is arranged so as to be screwed into the air screw thread hole9.

In particular, a male thread11bin an upper side of the air screw11is screwed into the air screw thread hole9, and a lower cylinder portion11ais arranged within the guide hole9aat a small gap.

In accordance with the structure mentioned above, it is possible to control an opening area of the upstream side air screw passage7aopen to the guide hole9aby rotating the air screw11.

Further, an idling operation of the engine is executed in accordance with the following manner.

The air screw11is rotated for adjustment, and the opening to the guide hole9aof the upstream side air screw passage7ais adjusted by the cylinder portion11a, whereby an idle air toward the downstream side air screw passage7bfrom the upstream side air screw passage7ais properly adjusted and determined.

Further, the idle air adjusted as mentioned above is supplied to the suction air passage2ain the downstream side from the throttle valve4via the idle air control passage5, whereby it is possible to well execute the idling operation of the engine.

On the other hand, in the low temperature region in which the engine atmosphere temperature is lower than the predetermined temperature, the drive member W including the output lever Wa moves upward, and the start opening and closing valve10opens the upstream side starter passage6ato the start opening and closing valve guide tube8.

In accordance with the structure, the first idle air for starting is supplied toward the downstream side starter passage6bfrom the upstream side starter passage6avia the start opening and closing valve guide tube8, and the air in total of the first idle air supplied from the starter passage6and the idle air supplied from the air screw passage7is supplied to the suction air passage2ain the engine side from the throttle valve4, via the idle air control passage5, whereby it is possible to execute a well engine start in the low temperature region.

Further, if the engine operation is continued, and the engine atmosphere temperature is increased from the temperature state mentioned above, the output lever Wa of the drive member W moved downward gradually, whereby the start opening and closing valve10closes the upstream side starter passage6agradually, and the start opening and closing valve10finally closes the upstream side starter passage6afully so as to stop the supply of the first idle air. Accordingly, it is possible to well execute a warm-up operation.

In the thereafter engine operation, the idling operation of the engine is well continued by the idle air supplied from the air screw passage7via the idle air control passage5.

In this case, in accordance with the idle speed control apparatus on the basis of the present invention, the air stream always exists within the idle air control passage5open to the suction air passage2ain the downstream side from the throttle valve4in all the operation regions of the engine.

In other words, the idle air is supplied toward the idle air control passage5from the air screw passage7in all the operation regions of the engine, and the first idle air is additionally supplied toward the idle air control passage5from the starter passage6in the low temperature region of the engine atmosphere temperature.

Since the air stream always exists from the downstream side passage5bof the idle air control passage5toward the inner side of the suction air passage2ain the downstream side from the throttle valve4, in all the operation regions of the engine, the blown-back fuel neither enters into the idle air control passage5nor the fuel stays within the passage5due to the air stream, even if the blown-back fuel within the suction air passage2ais going to enter into the downstream side passage5bof the idle air control passage5by the blowing-back of the fuel.

In accordance with the structure mentioned above, since the change of concentration of the air-fuel mixture is not generated by the staying fuel, particularly at a time of the idling operation of the engine, it is possible to execute a stable idling operation.

Further, since the single idle air control passage5is provided toward the suction air passage2ain the downstream side from the throttle valve4, and the other downstream side starter passage6band downstream side air screw passage7bmay only communicate with the idle air control passage5, it is possible to largely improve the freedom of the passage design.

Further, since the idle air control passage5is commonly used by the starter passage6and the air screw passage7, it is possible to reduce a working man hour of the passage.

Since a longitudinal axis X-X of the start opening and closing valve guide tube8continuously provided in the starter passage6and a longitudinal axis Y-Y of the air screw thread hole9including the guide hole9acontinuously provided in the air screw passage7are set in parallel to each other and are open toward the upper side in the drawing, it is possible to work to form the start opening and closing valve guide tube8including the downstream side starter passage6b, the downstream side air screw passage7b, and the air screw thread hole9including the guide hole9afrom the same direction, and it is possible to efficiently work them.

Further, it is possible to assemble the drive member w including the start opening and closing valve10and the air screw11including the cylinder portion11afrom the same direction, and it is possible to improve a maintenance property as well as it is possible to improve an assembling property.

DESCRIPTION OF THE REFERENCE SYMBOLS

1throttle body2Suction air passage2aSuction air passage in a downstream side from the throttle valve2bSuction air passage in an upstream side from the throttle valve4Throttle valve6Starter passage7Air screw passage10Start opening and closing valve11Air screw