JPH07666Y2 - In-cylinder direct injection spark ignition engine combustion chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a structure of a combustion chamber of a direct injection spark ignition engine in a cylinder.

[Conventional technology]

Fuel is directly injected into the cylinder and partially evaporated on the wall surface of the combustion chamber,
The combustion chamber of the direct injection spark ignition engine in which the vaporized fuel is carried along the wall surface of the combustion chamber or along the circumferentially extending groove formed on the wall surface of the combustion chamber to the spark plug facing the plug pocket and ignited by the spark plug is Known (for example, Shokai
56-65127, and Japanese Utility Model Publication No. 61-173728). The groove for guiding the evaporated fuel formed on the wall surface of the conventional combustion chamber gradually becomes deeper in the swirl direction as it gets closer to the spark plug, and the evaporated fuel in the groove is ignited as little as possible from the groove. I was supposed to carry it to the stopper.

[Problems to be solved by the device]

However, in the conventional structure in which the evaporated fuel is guided to the spark plug by the groove whose depth becomes deeper as it approaches the spark plug, and therefore the groove cross-sectional area increases, depending on the injection direction and the injection timing, it may be guided to the spark plug part. It has been found that the amount of fuel burned may become excessive, and in such a case, problems such as plug smoldering occur.

It is an object of the present invention to provide the groove with a fuel metering function by devising the shape of the groove so that an appropriate amount of fuel can be guided to the spark plug under any condition.

. [Means for Solving the Problems] According to the present invention, the above-mentioned problems can be achieved by the following in-cylinder direct injection spark ignition engine combustion chamber.

It is bounded by a recess formed on the top of the piston, and a plug pocket is formed on the side wall of the recess so as to open to the recess, and at least a portion of the fuel injected into the wall of the recess is swirled to vaporize the fuel. In a cylinder direct injection spark ignition engine combustion chamber in which a circumferentially extending groove that guides the spark plug side facing the plug pocket is formed, at least a part of the groove is hit with the injected fuel. A direct injection type spark ignition engine combustion chamber for a direct injection cylinder, characterized in that a measuring portion is formed whose groove cross-sectional area gradually decreases from the position side toward the plug pocket side.

[Action]

In the combustion chamber of the present invention, of the fuel injected from the fuel injection valve, the fuel that hits the wall surface of the recess and the bottom of the groove is attached to the wall surface and evaporated, and is swirled and guided to the groove for ignition. The plug is guided to the plug pocket that it should face, and is ignited by the spark plug and burns. Since the groove has a metering part whose cross-sectional area is gradually reduced in the swirl direction, a rich mixture containing the required amount of fuel is metered up to the plug pocket and supplied to the vicinity of the spark plug. It Therefore, when the amount of fuel is excessive, more than the required amount of fuel is expelled from the groove, disperses on the swirl, and disengages from the vicinity of the spark plug.
Thus, an unnecessarily large amount of fuel is prevented from flowing into the plug pocket, and spark smolder is prevented.

〔Example〕

A preferred embodiment of a direct injection type spark ignition engine combustion chamber according to the present invention will be described below with reference to the drawings. First
FIGS. 3 to 3 show the first embodiment, and FIG. 4 shows the second embodiment.

In the first and second embodiments of FIGS. 1 to 4, the combustion chamber 2 is defined by a cylinder head 4, a piston 6 and a cylinder bore 8, and the piston 6 is opened upward at the top thereof. The combustion chamber 2 has a concave portion 10 and the space inside the concave portion 10 constitutes a part of the combustion chamber 2. The wall surface of the recess 10 is
It has a curved bottom surface 12 and a side surface 14, and the bottom surface 12 and the side surface 14 are smoothly slid to define a part of the combustion chamber 2 inside. The cross-sectional shape of the recess 10 in the direction orthogonal to the axis is smooth, circular or nearly circular so as not to damp the swirl. The wall surfaces 12 and 14 of the recess 10 constitute evaporation wall surfaces that evaporate the fuel injected by the fuel injection valve 16 when the fuel is injected.

The piston 6 has a plug pocket 22 formed in the outer peripheral wall 18 of the recess 10 for receiving the spark plug 20 without interfering when the piston 6 rises near the top dead center. It is open to the side surface 14 of 10. The plug pocket 22 is open upward so that the spark plug 20 can be received.

A circumferentially extending groove 24 is formed on the side surface 14 of the recess 10 at a position substantially corresponding to the plug pocket 22 in the vertical direction. The groove 24 is recessed radially outward from the side surface 14 of the recess 10. There is. The groove 24 extends over at least a part of the circumferential length of the recess 10 and at least the fuel injected from the fuel injection valve 16 is injected.
It extends toward the plug pocket 22 side from the position 28 where the 30 hits. The arrow 32 indicates the flow direction of the swirl generated in the combustion chamber, and the swirl is necessary to promote combustion evaporation and is generated by using a swirl port as the intake port.

The groove 24 has, at least in a part of its circumferential length, a measuring portion 26 whose groove cross-sectional area is gradually reduced from the fuel hit position 28 side toward the plug pocket 22 side. Has been given the fuel metering function. That is, when the fuel amount is small, the fuel is directly guided to the plug pocket 22 side, and when the fuel amount is excessive, the amount exceeding a certain value is measured.
At 26, when the fuel is gradually ejected from the groove 24 and is carried to the spark plug portion, it is possible to make sure that an appropriate amount of fuel is measured. However, the groove 24 may disappear on the upstream side of the plug pocket 22. In short, the groove 24 has a metering section 26 on the upstream side of the plug pocket 22 so that an appropriate amount of fuel is supplied near the spark plug. Just do it. The groove 24 having the measuring portion 26 provided with such a measuring function is not found in the conventional example and is a novel point in the present invention.

The first embodiment and the second embodiment differ in how to reduce the groove cross-sectional area. In the first embodiment, FIGS.
As shown in the figure, the groove 24 has a bottom surface 24a and a side surface 24b.
24b is in a plane orthogonal to the piston axis and is in plan view (when the plane orthogonal to the piston axis is viewed from above the piston)
In addition, it has a three-month shape, and the bottom surface 24a is a concavely smoothly curved surface from the groove bottom side end of the side surface 24b toward the upper end of the recess 10. Then, the weighing unit 26 has a three-month shaped side face 24.
It is formed on the downstream side in the swirl flow direction with respect to the thickest part in the circumferential direction of b, and is formed in a portion where the depth of the bottom surface 24a gradually decreases in the swirl flow direction. Groove containing weighing section 26
24 ends upstream of the plug pocket 22 in the swirl flow direction, where the bottom surface 24a of the groove 24 hangs on the side surface 14 of the recess 10.

In the second embodiment, as shown in FIG. 4, the groove 24 has a bottom surface 24c.
And a pair of side faces 24d and 24e extending from the bottom face 24c to the side face 14 of the recess 10 at the top and bottom thereof. The bottom surface 24c extends deeply in the position 28 where the fuel hits and extends circumferentially from there toward the plug pocket 22 and ends smoothly in the vicinity of the plug pocket 22 by smoothly hanging on the side surface 14 of the recess. The pair of side surfaces 24d, 24e are closer to each other as they approach the plug pocket 22 in the circumferential direction, and the groove width is reduced, and the reduced portion is the measuring portion 26.
Is formed.

Next, the operation will be described.

A part of the injected fuel 30 injected from the fuel injection valve 16 is the recess 10
Adheres to the wall surface of and is evaporated there, and the evaporated fuel is
Of the spark plug, carried along swirl 32 along plug wall 22 along the groove 24 formed mainly in recess 10.
Ignite at 20 and burn. When the evaporated fuel is guided to the groove 24 and moves to the plug pocket 22, the evaporated fuel passes through the metering portion 26 provided in at least a part of the groove 24, but when the injected fuel amount is too large, the excess portion is the metering portion 26. Out of groove 24 with spark plug
20 The fuel is removed from the portion that is most recently transported, that is, an appropriate amount is measured, and in the vicinity of the spark plug 20, not too much fuel is always transported and completely burned. Therefore, the ignition plug smolder does not occur. Further, it becomes possible to inject fuel into the groove 24 for a long period of time, and the degree of freedom of nozzle arrangement is improved.

Further, since the groove cross-sectional area on the side where the injected fuel hits is larger than that of the metering portion 26, the required fuel can be collected even when the injected fuel amount is relatively small.

[Effect of device]

 According to the present invention, the following effects can be obtained.

Since at least a part of the groove 24 in the circumferential direction is provided with a metering section 26 whose groove cross-sectional area decreases toward the downstream side in the swirl flow direction, the fuel carried to the plug pocket 22 is metered to an appropriate amount or less and ignited. Can be stabilized and
It is possible to prevent problems such as smoldering of the ignition plug.

[Brief description of drawings]

1 is a plan view of a cylinder direct injection type spark ignition engine combustion chamber according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of the combustion chamber of FIG. 1, and FIG. 1 is a sectional view of the combustion chamber of FIG. 1 taken along the line III-III, and FIG. 4 is a sectional view of a cylinder injection type spark ignition engine combustion chamber according to a second embodiment of the present invention. 2 ... Combustion chamber 6 ... Piston 10 ... Recess 12 ... (Recess 10) Bottom 14 ... (Recess 10) Side 16 ... Fuel injection valve 18 ... (Recess 10) Outer wall 20 ... … Spark plug 22 …… Plug pocket 24 …… Groove 24a …… Bottom surface (of groove 24) 24b …… Side surface of (groove 24) 24c …… Bottom surface of (groove 24) 24d, 24e …… Side surface of (groove 24) 26 …… Weighing unit 28 …… Position where injected fuel hits 30 …… Injected fuel 32 …… Swirl flow

Claims (1)

[Scope of utility model registration request] 1. A piston pocket is defined by a recess formed on the top of the piston, and a side wall of the recess is provided with a plug pocket opening to the recess, and at least a part of the plug wall is sprayed onto the wall of the recess. In a cylinder direct injection spark ignition engine combustion chamber in which a groove extending in the circumferential direction for guiding the evaporated fuel on the swirl to the spark plug side facing the plug pocket portion is formed, the fuel is injected into at least a part of the groove. An in-cylinder direct injection spark ignition engine combustion chamber, characterized in that a metering portion is formed in which the groove cross-sectional area gradually decreases from the side where the injected fuel hits toward the plug pocket side.