JP2003113722A - Engine with plurality of exhaust valves - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce HC resulting from a discharge of liquid gasoline in an exhaust stroke. SOLUTION: In an engine with a plurality of exhaust valves 8 and 9, a valve cutoff device for holding both rocker arms 6 and 7 disposed for the respective exhaust valves, selectively, coupled or relatively displaceable about a turning angle uncouples both rocker arms and holds one exhaust valve 9 closed at an engine start-up. Liquid gasoline stagnant in a gap between a perimeter portion of a valve element of one of the two exhaust valves and a valve seat can be prevented from being discharged in an exhaust stroke, so that at an engine start-up, the discharge of liquid gasoline stagnant on the exhaust valves can be halved to reduce the amount of HC resulting from an unburnt component in exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine having a plurality of exhaust valves.

[0002]

2. Description of the Related Art Conventionally, for example, an automobile engine provided with a plurality of exhaust valves, for example, two cylinders per cylinder.
Some are equipped with two exhaust valves. In such an engine, each exhaust valve always operates at the same or different valve timing except when the valve is stopped (for example, Japanese Patent No. 316073).
No. 9).

[0003]

In the gasoline engine for automobiles, the HC contained in the exhaust gas is due to the unburned components of the gasoline, and especially when starting the engine when the engine is cold. Are emitted in relatively large amounts, which is a problem in air pollution. As a result of analyzing the phenomenon in which the HC is generated, the gasoline in the air-fuel mixture sucked from the intake port becomes a liquid and adheres to various parts of the combustion chamber.
Moreover, it was found that the adhered gasoline was not burnt and was discharged in the exhaust stroke because the wall surface of the combustion chamber was cold.

When the timing at which the gasoline is discharged is analyzed in more detail, the gasoline adhering to the combustion chamber travels through the ceiling of the combustion chamber and the valve body 31a of the exhaust valve 31 as shown by an arrow G in FIG. It was found that liquid gasoline was accumulated in the wedge-shaped gap 33 between the peripheral portion of the valve seat 32 and the valve seat 32, and the accumulated liquid gasoline was discharged all at once at the same time when the exhaust valve was opened during the exhaust stroke. . The wedge-shaped gap 33 is
This is caused by forming the valve body around the valve in the engine into a shape necessary for ensuring the function and durability, and the wedge-shaped gap cannot be eliminated.

Further, there is a conventional engine having two exhaust valves, one of which is in a stopped state. However, even in that case, the stopped state of the valve is not the one in which the valve is completely closed (fully closed).

Alternatively, when the engine is mounted, the layout may be inclined. In such a case, when a plurality of exhaust valves are arranged in the inclination direction, a larger amount of liquid gasoline is accumulated in the lower exhaust valve.

[0007]

[Means for Solving the Problems] As described above, to reduce the amount of HC that results from the discharge of liquid gasoline accumulated between the peripheral portion of the valve body of the exhaust valve and the valve seat during the exhaust stroke. In the present invention, an engine (1) having a plurality of exhaust valves (8, 9), wherein at least one (9) of the plurality of exhaust valves (8, 9) is provided. ) For selectively switching one of the operating state and the rest state (6, 7, 16,
18 and 19), and the valve deactivating device puts the at least one exhaust valve (9) into a deactivating state in which the exhaust valve (9) is fully closed when the engine is started.

According to this, for example, in an engine having two exhaust valves, one of them is brought into a fully closed state when the engine is started. It is possible to prevent the liquid gasoline accumulated in the gap between the valve section and the valve seat from being discharged in the exhaust stroke, and to reduce the amount of the liquid gasoline accumulated in the exhaust valve when the engine is started.

Alternatively, in an engine (1) having a plurality of exhaust valves (8, 9), at least one (9) of the plurality of exhaust valves (8, 9) is selectively switched from an operating state to a rest state. Valve shut-off device (6/7/16/1)
8 and 19), the engine (1) is mounted to be tilted with respect to the vehicle body, and the exhaust valve (9) for setting the rest state is located on the lower side in the tilting direction of the engine (1). I was supposed to.

According to this, when liquid gasoline travels along the wall surface and accumulates between the valve body of the exhaust valve and the valve seat, the exhaust valve on the lower side in the inclined direction, which is likely to accumulate, is put into a rest state, so that the rest is performed in the same manner as described above. It is possible to suppress the discharge of the liquid gasoline accumulated in the exhaust valve in the state in the exhaust stroke, and it is possible to further reduce the total discharge amount of the liquid gasoline accumulated in the plurality of exhaust valves. Here, the idle state means a state in which exhaustion by the exhaust valve is not actively performed, and includes that the corresponding exhaust valve is in a state of a minute lift amount in the exhaust stroke.

Further, the exhaust valve (9) to be in the rest state is the exhaust valve (8) to be kept in the operating state.
According to the fact that it is formed with a larger diameter, the valve that is in the fully closed state or the rest state has a larger diameter, so the amount of liquid gasoline accumulated in the valve with the larger diameter is relatively large. The total amount of liquid gasoline accumulated in a plurality of exhaust valves can be further reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail based on specific examples shown in the accompanying drawings.

FIG. 1 is a side view schematically showing an engine mounted state of an automobile to which the present invention is applied. The engine 1 shown in the figure is, for example, an in-line four-cylinder engine, is installed vertically with respect to the vehicle body 2, and has its axis C.
The vehicle rear side of (the crankshaft axis) is the horizontal line H of the vehicle body 2.
It is mounted on the vehicle body 2 so as to incline downward by an angle θ.

An exhaust valve structure in the engine 1 of this illustrated example will be described below with reference to FIGS. 2 and 3. FIG. 2 is shown in the same mounted state of the engine 1 and in the vertical relationship. As shown in FIG. 2, the exhaust camshaft 3
A cam 4 having an oval cross section is integrally formed therewith, and a rocker shaft 5 is provided below the cam shaft 3 in parallel with the cam shaft 3.

As shown in FIG. 3, two rocker arms 6 and 7 are pivotally supported on the rocker shaft 5 so as to be adjacent to each other and to be capable of relative angular displacement. Each of the rocker arms 6 and 7 is formed with an arm portion extending in the radial direction of the rocker shaft 5 from a portion pivotally supported by the rocker shaft 5, and two exhaust valves are provided at each free end of each arm portion. The stem ends of 8 and 9 are in contact with each other.

The exhaust valves 8 and 9 are provided with a return spring 11
The spring is constantly urged in the valve closing direction by a.11b.
In the closed state, the valve body 8a (9a) of the exhaust valve 8 (9)
Are in contact with the valve seat 12 provided in the exhaust port of each of the exhaust valves 8 and 9.

In addition, inside the two rocker arms 6 and 7, there is a connection switching mechanism for switching between a state in which they can be relatively angularly displaced, that is, a rest mode, and a state in which they can swing integrally, that is, a normal mode. Is provided. The connection switching mechanism will be described below.

The rocker arm 6 on the left side in FIG.
In the illustrated example, a cam follower 13 that contacts the cam 4 is provided. The bearing of the cam follower 13 is a needle bearing in the illustrated example, and the cylindrical inner race 14 thereof is provided integrally with the rocker arm 6 so as to be embedded therein. Due to the inner peripheral surface of the inner race 14, the rocker shaft 5
The first guide hole 15 is formed parallel to the axis of the. The first guide hole 15 is formed as a bottomed hole that opens to the right rocker arm 7 side. A connecting pin 16 is coaxially received in the first guide hole 15 so as to be slidable in the axial direction.

The right rocker arm 7 in FIG.
A cylindrical member having the same inner and outer diameters as that of the inner race 14 is embedded, and a substantially bottomed second guide hole 17 that opens to the left rocker arm 6 side is formed by the inner peripheral surface thereof. The two guide holes 15 and 17 are aligned with each other when the valve is closed. A stopper pin 18 having a cylindrical shape with a bottom is coaxially received in the second guide hole 17 so as to be slidable in the axial direction. The bottom of the stopper pin 18 is in contact with one end of the connecting pin 14. A compression coil spring 19 is interposed between the cylindrical bottom surface of the stopper pin 18 and the bottom portion of the second guide hole 17, and the compression coil spring 19 directs the stopper pin 18 toward the connecting pin 16 side. Is constantly being blasted.

In the rocker shaft 5, an oil supply passage 21 for supplying the lubricating oil pumped up from the oil pan.
Are formed. The oil supply passage 21 communicates with a bottom portion on the left side in the drawing of the first guide hole 15 via a communication hole 22 formed in a pivotal support portion of the rocker arm 6 on the left side of the rocker shaft 5.

The connection switching mechanism interrupts the hydraulic pressure applied from the oil supply passage 21 to the connection pin 16 in the first guide hole 15 by controlling the opening and closing of a solenoid valve (not shown) according to the operating state of the engine. Works by.

In this way, the valve pausing device is constructed, and in the pausing mode, hydraulic pressure does not act on the connecting pin 14. In that case, the elastic force of the compression coil spring 19 pushes the connecting pin 16 into the first guide hole 15 so that the pins 14 and 18 respectively correspond to the corresponding guide holes 15 and 17 as shown in FIG. It will be in the state of being accommodated inside (the state of being aligned with the axial direction). In this state, the rocker arms 6 and 7 can be angularly displaced relative to each other. Therefore, the rocker arm 6 on the left side of FIG. 3 is driven by the cam 4 profile to perform the opening / closing valve movement, but the other rocker arm 7 separated from the rocker arm 6 is not driven by the cam 4 and the corresponding exhaust valve 9 is in the rest state. In the illustrated example, it is in a fully closed state.

On the other hand, the valve is switched to the normal mode at the timing when the valve is closed, and the hydraulic pressure is applied to the connecting pin 16 accordingly. Then, as shown in FIG. 4, the compression coil spring 1
9 against the resilient force of the stopper pin 18 to the second guide hole 1
Connecting pin 1 so that it can be immersed in the back as shown in 7
6 is extruded. Therefore, both rocker arms 6 and 7 are connected through the connecting pin 16 and can swing integrally, and the two exhaust valves 8 and 8
9 are simultaneously driven to perform an opening / closing valve movement (operating state).

In the connection switching mechanism of the illustrated example,
When the rest mode is set, the hydraulic pressure is released and the connecting pin 16 is returned to the inside of the rocker arm 6 by the spring force, but the reverse is also possible. That is, in the normal mode, the connecting pin is placed between both rocker arms by the spring force to be in the connected state, and in the rest mode, hydraulic pressure is applied against the spring force to return the connecting pin into the rocker arm to separate the two rocker arms from each other. All you have to do is to put it into the

Then, when the engine is started, the rest mode is performed. For example, when the engine is started in a cold state, the wall of the combustion chamber is cold, so the gasoline in the intake air mixture becomes liquid and adheres to various parts of the combustion chamber, and the adhered gasoline burns. Through the ceiling of the room,
Liquid gasoline accumulates in a wedge-shaped gap 20 (see FIG. 5) between the valve seat 12 and the peripheral edges of the valve bodies 8a and 8b of the exhaust valves 8 and 9.

On the other hand, the liquid gasoline accumulated in one of the two exhaust valves 8 and 9 (9) as described above by performing the rest mode when the engine is started is
Since the exhaust valve 9 is at rest (fully closed in the example of FIG. 5), it is possible to suppress the exhaust in the exhaust stroke. Therefore, it is possible to reduce the amount of liquid gasoline discharged when the engine is started.

It should be noted that it is not necessary to always perform the sleep mode when starting the engine. As described above, the liquid gasoline adheres to the wall surface of the combustion chamber when the engine is cold. When the engine is started immediately after it is stopped, a warm-up state may be detected by a cooling water temperature sensor or the like, and when the engine is at or above the warm-up temperature, the engine may be started in the normal mode. Further, in the illustrated example, the number of exhaust valves is two, but the number of exhaust valves is not limited to two and may be three or more. In that case, at least one of the exhaust valves should be used. Fully closed.

Further, when the engine 1 is mounted with an inclination as shown in FIG. 1, the liquid gasoline adhering to the combustion chamber is likely to be transmitted to the side inclined downward. In that case, for example, the right exhaust valve 9 in FIG.
Should be positioned on the side that is lower due to the inclination. As a result, the exhaust valve 9, which tends to accumulate liquid gasoline due to the inclination, is closed in the rest mode, so that a larger amount can be prevented from being discharged. The inclination direction of the engine 1 is not limited to the vertical installation in FIG.
In some cases, when the exhaust valve is tilted in the cylinder row direction and a plurality of exhaust valves are provided in the horizontal position, the exhaust valve on the lower side in the tilt direction may be in a rest state.

In such a tilt-mounted engine, the exhaust valve, which is provided on the lower side of the tilt and is stopped, does not have to be fully closed as shown by the solid line in FIG.
As shown by the imaginary line, the rest state may be set with a minute lift amount. Even in this case, a larger amount of liquid gasoline flows and accumulates in the exhaust valve on the lower side of the slope, the amount of discharge thereof can be suppressed, and HC can be reduced. Furthermore, if the exhaust valve that is put into the rest state in the rest mode is set to the fully closed state in which the lift amount is lost, further reduction of HC can be achieved.

Further, as shown in FIG. 5, the diameter D2 of the valve body 9a of the exhaust valve 9 which is closed in the rest mode is larger than the diameter D1 of the valve body 8a of the exhaust valve 8 which constantly performs the opening / closing movement. It is good to have a large diameter. As a result, the amount of accumulated liquid gasoline is larger in the exhaust valve 9 having a large diameter, and it is possible to prevent a larger amount of the liquid gasoline accumulated in the entire exhaust valve from being discharged.

[0031]

As described above, according to the present invention, in the case of liquid gasoline which is accumulated especially in the cold start in the gap between the valve body and the valve seat caused by the shape required for ensuring the function and durability of the valve. Since the exhaust from the exhaust valve which is in the closed state, which is in the fully closed state, is suppressed, it is possible to reduce the total amount of liquid gasoline accumulated in multiple exhaust valves, which is caused by unburned components in the exhaust gas. HC to do
The amount of can be reduced.

Further, in an engine mounted in a tilted manner, when liquid gasoline travels along the wall surface and accumulates between the valve body of the exhaust valve and the valve seat, it easily accumulates in the lower exhaust valve, It is advisable to put the exhaust valve, which easily accumulates, in a resting state (a minute lift amount or a fully closed state), and in this case, the total discharge amount of liquid gasoline can be further reduced.

Further, it is preferable that the exhaust valve to be in a resting state is formed to have a larger diameter than that of the exhaust valve to be kept in an operating state. Since the amount of liquid gasoline that is longer than that in the state and whose emission can be suppressed by stopping the exhaust valve is relatively large, the total emission amount of liquid gasoline can be further reduced.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an engine mounted state of an automobile to which the present invention is applied.

FIG. 2 is a front view showing an exhaust valve structure according to the present invention.

FIG. 3 is a fragmentary plan view of a main portion in a rest mode, which is seen along an arrow line III-III in FIG.

FIG. 4 is a view corresponding to FIG. 3 in a normal mode of both exhaust valves.

FIG. 5 is a side view of essential parts showing a difference in outer diameter of valve bodies of both exhaust valves.

FIG. 6 is an enlarged side view of an essential part showing a gap between a valve body and a valve seat.

[Explanation of symbols]

1 engine 6.7 Rocker arm (Valve stop device) 8.9 Exhaust valve 16 connecting pin (valve stop device) 18 Stopper pin (Valve stop device) 19 Compression coil spring (valve resting device)

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 4, 2001 (2001.10.
4)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) F01L 13/00 F01L 13/00 302F (72) Inventor Kazuyuki Seko 1-4-1, Chuo, Wako-shi, Saitama F-terms in Honda R & D Co., Ltd. EA27 FA18 GA01 HF05Z

Claims (3)

[Claims] 1. An engine having a plurality of exhaust valves, comprising a valve deactivation device for selectively setting at least one of the plurality of exhaust valves to one of an operating state and a deactivation state, the valve deactivation An engine having a plurality of exhaust valves, wherein the device puts at least one of the plurality of exhaust valves into a resting state in which the exhaust valve is fully closed when the engine is started. 2. An engine having a plurality of exhaust valves, comprising a valve deactivation device for selectively setting at least one of the plurality of exhaust valves to either one of an operating state and a deactivation state, wherein the engine is The plurality of exhaust valves according to claim 1, wherein the exhaust valve is mounted so as to be inclined with respect to a vehicle body, and the exhaust valve that is in the rest state is located on a lower side in a tilt direction of the engine. engine. 3. The plurality of exhausts according to claim 1, wherein the exhaust valve that is in the rest state is formed to have a larger diameter than the exhaust valve that is kept in the operating state. Engine with valves.