JPH05180007A - Intake device for gasoline engine - Google Patents

Abstract

PURPOSE:To prevent hunting of the housing of a shut-off valve adapted to be open during high load operation and disposed in an auxiliary passage of an intake port which is divided by a partition wall laid along a direction in which the intake port is formed, into a main passage and the auxiliary passage, by connecting and associating the shut-off valve to a throttle valve. CONSTITUTION:An intake port 5 formed on one lateral side of a cylinder 2 of an engine is communicated with an air cleaner 11 through a passage 8 in a shut-off valve casing 7 and a venturi part 10 of a carburetor 9, and the inside of the intake port 5 is divided by a partition wall laid along a direction in which the intake port 5 is formed, into an upper main passage 28 and a lower auxiliary passage 29. A shut-off valve 30 for the auxiliary passage 29 is disposed in the passage 8 in the shut-off valve easing 7, an input arm 3 fixed to the valve shaft head part of the shut-off valve 30 is associated and connected to a throttle input arm 14 through the intermediary of a link rod 32. With this arrangement, the shut-off valve 30 is opened by means of the link rod 30 during high load operation where the opening degree of a throttle valve 13 is large, and accordingly, the volume of air which copes with the load is fed into an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an intake system for a gasoline engine.

[0002]

2. Description of the Related Art As a conventional art of an intake system for a gasoline engine, there is one shown in FIG. This is the throttle valve 1
01 The inside of the intake port 102 on the downstream side is divided into a main passage 104 and an auxiliary passage 105 by a partition wall 103 along the port formation direction, and an opening / closing valve 106 of the auxiliary passage 105 is provided on the downstream side of the throttle valve 101, so that when the load is high. The on-off valve 106 is opened, and the on-off valve 106 is closed when the load is low.

According to this structure, when the load is high,
The auxiliary passage 105 is opened, and a wide passage cross-sectional area of the intake port 102 is ensured, whereby a large amount of air-fuel mixture flowing into the intake port 102 at the time of high load is introduced into the intake port 102.
The fuel-air mixture is supplied to the combustion chamber 109 with a high filling efficiency, and a high output is ensured. on the other hand,
When the load is low, the auxiliary passage 105 is closed, and the passage cross-sectional area of the intake port 102 is narrowed. This speeds up the low-speed air-fuel mixture that flows into the intake port 102 when the load is low, and causes condensation of gasoline on the port wall. Prevented, combustion chamber 1
The air-fuel ratio of the air-fuel mixture supplied to 09 is maintained appropriately.

By the way, in this prior art, the on-off valve 10
6 is opened and closed based on the detection of intake negative pressure downstream of the throttle valve 101. That is, the throttle valve 101
When the load is large, the throttle valve 101
Although the downstream intake negative pressure becomes small, the diaphragm device 108 opens and closes the opening / closing valve 106 based on the fact that the small intake negative pressure is detected by the negative pressure introducing passage 107. On the other hand, when the opening degree of the throttle valve 101 is small and the load is low, the intake negative pressure on the downstream side of the throttle valve 101 increases, but the diaphragm device 108 detects the large intake negative pressure in the negative pressure introducing passage 107. On-off valve 1
06 is closed and interlocked.

[0005]

In the above-mentioned prior art, the opening / closing valve 106 is opened / closed based on the detection of the intake negative pressure downstream of the throttle valve 101. However, since the intake negative pressure pulsates,
The on-off valve 106 easily causes hunting. For this reason,
Originally, at the time of high load when the opening / closing valve 106 should be opened, the opening / closing valve 106 is temporarily closed and the auxiliary passage 105 is closed, and the efficiency of charging the air-fuel mixture into the combustion chamber 109 is reduced, and the output May cause deterioration. Also, originally, the on-off valve 106
When the load is low, the on-off valve 106 is temporarily opened and the auxiliary passage 105 is opened, and the air-fuel mixture passes through the inside of the intake port 102 at a low speed, and gasoline is condensed on the port wall. As a result, the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 109 may deviate from the appropriate value.

An object of the present invention is to provide an intake device for an engine which can prevent hunting of an on-off valve.

[0007]

[Means for Solving the Problems]

(First Invention) As shown in FIG. 1 or FIG. 3, the first invention comprises a main passage 28 and an auxiliary passage 29 in the intake port 5 downstream of the throttle valve 13 with a partition wall 27 along the port forming direction.
And the auxiliary passage 29 on the downstream side of the throttle valve 13.
In the intake device for a gasoline engine, the opening / closing valve 30 is provided, and the opening / closing valve 30 is opened at the time of high load, and the opening / closing valve 30 is closed at the time of low load. And

The opening / closing valve 30 is interlockingly connected to the throttle valve 13, and the opening / closing valve 30 is opened / closed based on the operation of the throttle valve 13.

(Second invention) As shown in FIG. 1, the second invention is such that, in the intake system for a gasoline engine of the first invention, the main passage 28 is arranged closer to the intake valve port 6 than the auxiliary passage 29. , Is characterized.

[0010]

[Action]

(First Invention) At high load, the opening / closing valve 30 is opened based on the operation of the throttle valve 13. In this case, the auxiliary passage 29 is opened, and a wide passage cross-sectional area of the intake port 5 is ensured, whereby a large amount of air-fuel mixture flowing into the intake port 5 at the time of high load passes through the intake port 5 without stagnation. , The air-fuel mixture is supplied to the combustion chamber 4 with high filling efficiency, and high output is secured. On the other hand, when the load is low, the opening / closing valve is closed based on the operation of the throttle valve 13. in this case,
The auxiliary passage 29 is closed, and the passage cross-sectional area of the intake port 5 is narrowed. As a result, the low-speed air-fuel mixture flowing into the intake port 5 at low load is sped up, the condensation of gasoline on the port wall is prevented, and combustion is performed. The air-fuel ratio of the air-fuel mixture supplied to the chamber 4 is maintained at an appropriate level.

As described above, the opening / closing of the opening / closing valve 30 is performed based on the operation of the throttle valve 13, but since the operation of the throttle valve 13 is stable, the opening / closing of the opening / closing valve 30 pulsates and unstable intake air is pulsated. Hunting of the on-off valve 30 does not occur unlike the case where it is performed based on negative pressure. Therefore, the output does not decrease when the load is high, and the air-fuel ratio of the air-fuel mixture supplied to the fuel chamber 4 does not deviate from the appropriate value when the load is low.

(Second invention) In addition to the operation of the first invention,
It works as follows. The air-fuel mixture always passes through the main passage 28 regardless of the level of the load, but the air-fuel mixture that has passed through the main passage 28 quickly flows into the intake valve port 6 through a short path as indicated by an arrow 44, and the intake port 5 is opened. Condensation of gasoline is prevented. Therefore, regardless of the load level, the combustion chamber 4
The air-fuel ratio of the air-fuel mixture supplied to is maintained more appropriate.

[0013]

【The invention's effect】

(First Invention) Although the opening / closing valve is opened / closed based on the operation of the throttle valve, the operation of the throttle valve is stable. Therefore, the opening / closing of the opening / closing valve is performed based on the unstable intake negative pressure pulsating. Unlike the case described above, hunting of the on-off valve does not occur. Therefore, the output does not decrease when the load is high, and the air-fuel ratio of the air-fuel mixture supplied to the fuel chamber does not deviate from the appropriate value when the load is low.

(Second Invention) In addition to the effects of the first invention, the following effects are exhibited. The air-fuel mixture always passes through the main passage regardless of whether the load is high or low, but the air-fuel mixture that has passed through the main passage quickly flows into the intake valve port through a short path to prevent condensation of gasoline at the intake port. Therefore, the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber is maintained more appropriate regardless of the load level.

[0015]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a vertical sectional view of an upper portion of a gasoline engine according to a first embodiment of the present invention. FIG. 2 is a perspective view of the interlocking mechanism of the on-off valve used in the gasoline engine of FIG.

The gasoline engine shown in FIG. 1 has a cylinder 2 formed on the upper side of a crankcase 1.
The cylinder head 3 is assembled on the upper side of the.
A combustion chamber 4 is recessed in the lower surface of the cylinder head 3.

The structure of the intake system of this engine is as follows. An intake port 5 is formed on the lateral side of the cylinder 2, and an upward intake valve port 6 faces the combustion chamber 4. The intake port 5 communicates with an air cleaner 11 via a case internal passage 8 of the on-off valve case 7 and a venturi portion 10 of the carburetor 9. The carburetor 9 is provided with a choke valve 12 on the upstream side of the venturi portion 10 and a throttle valve 13 on the downstream side. The throttle valve 13 is constructed by fixing a throttle input arm 14 to the valve shaft head.

The structure of the speed governor of this engine is as follows. The throttle input arm 14 is linked to a governor lever 16 via a throttle link rod 15. The governor lever 16 is linked to a throttle lever 18 via a governor spring 17 and is linked to a centrifugal governor 19.

In this speed governor, the throttle lever 18
The spring force 20 is applied to the governor lever 16 according to the rotational speed setting position, and the governor force 21 is applied to the governor lever 16 according to the actual rotational speed of the engine. Then, the governor lever 16 swings about its pivot axis 22 so that the spring force 20 and the governor force 21 exerted on the governor lever 16 in opposite directions balance each other.

As the load on the engine increases and the actual engine speed decreases, the governor force 21 decreases,
The governor lever 16 swings toward the arrow 23 side, the throttle interlocking rod 15 is pushed in the direction of the arrow 24, the throttle input arm 14 rotates as shown by the arrow 25, and the throttle valve 13 moves by the arrow 26 as shown in FIG. As described above, the opening degree is increased, the supply amount of the air-fuel mixture to the combustion chamber 4 is increased, and the lowered actual rotation speed of the engine is restored. On the other hand, when the load on the engine decreases and the actual engine speed increases, contrary to the above case, the throttle valve 1
The opening degree of 3 decreases, the supply amount of the air-fuel mixture to the combustion chamber decreases, and the increased actual engine speed returns to the original value.

As shown in FIG. 1, in the intake system of the engine described above, the passage cross-sectional area of the intake port 5 is changed according to the level of the load at which the supply amount of the air-fuel mixture to the combustion chamber 4 increases or decreases. The following innovations have been made. The inside of the intake port 5 is vertically divided into two parts by a partition wall 27 along the port forming direction, and a main passage 28 is formed on the upper side and an auxiliary passage 29 is formed on the lower side of the intake port 5. An opening / closing valve 30 for an auxiliary passage 29 is provided in the case passage 8 of the opening / closing valve case 7. As shown in FIG. 2, the opening / closing valve 30 is configured by fixing an opening / closing valve input arm 31 to the valve shaft head. The on-off valve input arm 31 is interlockingly connected to the throttle input arm 14 via the on-off valve interlocking rod 32 as follows.

As shown in FIG. 2, the on-off valve interlocking rod 32
The rear end side bent portion 33 is fitted into the round hole 34 of the throttle input arm 14, and the front end side bent portion 35 of the open / close valve interlocking rod 32 is inserted into the open / close longitudinal guide hole 3 of the open / close valve input arm 31.
It is loosely fitted in 6. Further, the on-off valve 30 is the biasing spring 3
It is urged toward the valve closing side by 7 and received by the valve seat (not shown).

Since the opening of the throttle valve 13 is small and the load of the throttle input arm 14 in the direction of arrow 25 is small from low load to medium load,
Even if the on-off valve interlocking rod 32 is pushed in the direction of the arrow 45, the bent portion 35 on the tip end side thereof only floats in the guide hole 36.
The force is not transmitted from the throttle input arm 14 to the open / close valve input arm 31, and the open / close valve 30 is set to the biasing spring 3
It remains closed due to the biasing force of 7.

Further, the opening of the throttle valve 13 is large,
When the load on the throttle input arm 14 is increased in the direction of the arrow 25 from the time of over medium load to the time of high load, when the open / close valve interlocking rod 32 is pushed in the direction of arrow 45, the tip bending portion 35 of the open / close valve interlocking rod 32 is guided. The opening / closing valve input arm 31 is pressed by the throttle input arm 14 to rotate in the direction of arrow 39, and the opening / closing valve 30 rotates in the direction of arrow 40 to open the valve.

FIG. 3 is a view for explaining a gasoline engine according to a second embodiment of the present invention, and FIG. 3 (A) is a longitudinal sectional view of an essential part,
FIG. 3B is a perspective view of the interlocking mechanism of the on-off valve. In the second embodiment, as shown in FIG. 3 (A), the intake port 5
The inside is divided into a lower main passage 28 and an upper auxiliary passage 29 by a partition wall 27 along the port forming direction. Also,
The inside of the case passage 8 of the on-off valve case 7 is divided into a lower main passage inlet 42 and an upper auxiliary passage inlet 43 by a partition wall 41 extending along the passage forming direction. Auxiliary entrance section 4
An opening / closing valve 30 for an auxiliary passage 29 is provided in the inside of the valve 3. The main passage inlet portion 42 communicates with the main passage 28, and the auxiliary passage inlet portion 43 communicates with the auxiliary passage 29.

Also in this second embodiment, as in the first embodiment,
As shown in FIG. 3B, when the opening of the throttle valve 13 is small and the load of the throttle input arm 14 in the direction of arrow 25 is small from low load to medium load, the opening / closing valve interlocking rod is also small. Even if 32 is pushed in the direction of the arrow 45, the tip bent portion 35 only floats inside the guide hole 36, and the throttle input arm 14 opens and closes the opening / closing valve input arm 3.
1 is not transmitted, and the on-off valve 30 remains closed due to the urging force of the urging spring 37.

Further, the opening of the throttle valve 13 is large,
From the time of over medium load to the time of high load, the throttle input arm 14 pivots largely in the direction of arrow 25, so that the on-off valve interlocking rod 32 is largely pushed in the direction of arrow 45,
The tip bent portion 35 contacts the front end portion 38 of the guide hole 35, and the throttle input arm 14 moves from the opening / closing valve input arm 3
1 is pushed and it rotates in the direction of arrow 39,
Rotates in the direction of arrow 40 to open the valve.

The content of each embodiment of the present invention is as described above, but the present invention is not limited to the above embodiment.
In each of the above embodiments, the opening / closing valve is mechanically interlocked with the throttle valve, but instead of this, the opening / closing valve may be electrically interlocked with the throttle valve. For example, the throttle valve is provided with an opening detection means (rotary encoder, etc.), the opening / closing valve is linked to the opening / closing drive means (solenoid, etc.), and the opening / closing drive means is linked with the opening / closing drive means, so that the throttle valve can be operated under high load. Based on the fact that the opening degree detection means detects that the opening degree of the valve has increased, the opening / closing valve is opened by the opening / closing drive means, and the opening degree is detected when the opening degree of the throttle valve has decreased when the load is low. The opening / closing valve may be closed by the opening / closing drive means based on the detection by the means.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an upper portion of a gasoline engine according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an interlocking mechanism of an on-off valve used in the gasoline engine of FIG.

FIG. 3 is a diagram for explaining a gasoline engine according to a second embodiment of the present invention, FIG. 3 (A) is a longitudinal sectional view of a main part, FIG.
(B) is a perspective view of the interlocking mechanism of the on-off valve.

FIG. 4 is a schematic diagram of an intake device for a gasoline engine according to a conventional technique.

[Explanation of symbols]

5 ... intake port, 6 ... intake valve port, 13 ... throttle valve,
27 ... Partition wall, 28 ... Main passage, 29 ... Auxiliary passage, 30 ... Open / close valve.

Claims (2)

[Claims] 1. An intake port downstream of a throttle valve (13)
The inside of (5) is the main passage with the partition wall (27) along the port formation direction.
(28) and the auxiliary passage (29) are divided into two, an opening / closing valve (30) of the auxiliary passage (29) is provided on the downstream side of the throttle valve (13), and the opening / closing valve (30) is opened when the load is high. In the intake system for a gasoline engine, which is configured to close the opening / closing valve (30) when the load is low, the opening / closing valve (30) is interlocked with the throttle valve (13), and the throttle valve (13) is connected. (3) is constructed so as to open and close the opening / closing valve (30) based on the operation of (1). 2. The gasoline engine intake system according to claim 1, wherein the main passage (28) is arranged closer to the intake valve port (6) than the auxiliary passage (29). Intake device.