JPS597730A - Generating device of intake swirl in internal-combustion engine - Google Patents

Abstract

PURPOSE:To generate a swirl when an engine is operated at a low speed with a small load while improve an intake charging rate when the engine is operated at a high speed with a large load, by using a valve variable mechanism decreasing height of a swirl generating member smaller than the maximum lift of an intake valve. CONSTITUTION:At low speed and low loaded operation of an engine, a control cam 39 is rotated and a depressive amount of a lever 24 is decreased. A swivelling support point (a point where a back face 23a of a rocker arm 23 is contacted with a bottom end face 24a of the lever 24) of the rocker arm 23 is slightly moved in the direction of a spring 36. The rocker arm 23 is swivelled, and an intake valve 15 is lowered to a virtual line l1, then a strong swirl is generated in a cylinder 12 by a shroud wall 16 and an umbrella part 15a. At high speed and high loaded operation of the engine, the depressive amount of the lever 24 is increased, and the swivelling support point is largely moved in the direction of the spring 36, then the intake valve 15 is lowered to a virtual line l2, in this way, a charging rate of intake is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake vortex generation device for an internal combustion engine, and more particularly to an intake vortex generation device for an internal combustion engine having a variable valve lift mechanism that variably controls the lift amount of an intake valve according to engine operating conditions. .

Various measures have been taken in recent years to reduce harmful components, particularly NOx (nitrogen oxides), emitted from internal combustion engines. For example, by diluting the intake air-fuel mixture or by partially recirculating exhaust gas into the intake air, the maximum temperature of combustion can be lowered and NO
On the other hand, even in these cases, there is a strong need to improve the output and fuel efficiency of the engine as well as take measures against exhaust emissions.For this reason, it is necessary to suppress the generation of It is also necessary to have high combustion stability.

Conventionally, as a means for this purpose, a knee-loud wall that generates a vortex of intake air is provided on the inner wall of the intake boat (@
Publication 54-IO (see Publication No. 159-ke), Arashi.
In this case, the intake valve head is also formed with a similar round roof. 1 to 3 show the former. In the same figure, ('l + is an intake boat, (2
) indicates the J-no-I air boat, f3+ indicates the injection nozzle mounting hole, and (4) indicates the spark plug. As shown in detail in FIG. 3, the intake bow 1-+11 has a shroud wall (6
) is formed and therefore this shroud wall (
6), an intake swirl flow (intake swirl flow) is generated in the cylinder combustion chamber (7) as shown by the arrow in FIG. In this case, the height of the ceiling wall (6) is 11
) is set to be larger than the lift amount (maximum lift amount) of the intake valve (5), as shown in FIG.

In addition, even in the latter case, a shroud installed on the umbrella of the intake valve generates a swirling flow (vortex) of intake air inside the cylinder, and the height of this shroud is also set to be approximately the same as the lift amount of the intake valve. has been done.

However, in such a conventional intake vortex generating device, the shroud (6) for generating an intake vortex in the cylinder during low speed, low load operation of the engine,
Even when the intake valve (5) is at its maximum lift, the opening of the intake port (11) is partially covered, so when the engine is operating at high speeds and high loads, the air intake resistance (6) increases due to the intake valve (6). As a result, the filling efficiency of intake air into the cylinder (7) decreases, leading to a decrease in output, and
There was a problem in that the vortex in the cylinder (7) became excessive, causing misfires and resulting in unstable combustion.

This invention was made by focusing on such conventional problems, and in an intake vortex generation device for an internal combustion engine, the height of the vortex generation member is made smaller than the maximum lift of the intake valve, and a variable valve lift mechanism is used. When the engine is operating at low speeds and low loads, the lift amount of the intake valve is reduced to generate vortices, while when operating at high speeds and high loads, the lift amount is increased (by increasing the intake air filling efficiency, the problem mentioned above is solved). It aims to solve the problem.

The present invention will be explained below based on the drawings.

4 to 13 are diagrams showing an embodiment of the present invention. First, the configuration will be explained. In Figures 4 to 6, (11) indicates a cylinder head, and this cylinder head (old cylinder head) is closed with the cylinder hole of the cylinder block to form a combustion chamber (cylinder) (121). (13) (14) ) are the intake port and exhaust port formed in the cylinder head (11), and the intake bore 131 is the intake port (lube (15)).
The exhaust port (141 is opened and closed by an exhaust valve (not shown), respectively.Intake port 03
A shroud wall (16) protruding toward the cylinder (121 side) is formed along the circumferential direction so as to extend a part of the side wall of the opening. The height, that is, the protrusion length 1-11 from the open end of the intake port (13) is determined by the imaginary line (1-11) in FIG.
It is set approximately equal to the minimum lift amount of the intake valve (15) shown in 1) (the lift amount when the engine is operating at low speed and low load). In addition, the imaginary line (I12) in the figure indicates the intake valve at maximum lift (during high-speed, high-load operation of the engine).
The position of the intake valve (15) in the lift state (15) is shown, and the maximum lift amount is set to about twice the minimum lift amount by the variable valve lift mechanism. In addition,
The shroud wall (16) cooperates with the umbrella part (15a) of the intake nozzle (15) to form a swirling flow generating member that generates a swirling flow (vortex) of the intake air as shown by the arrow in FIG. ing.

Figures 7 and 8 show a variable valve lift mechanism (2) that variably controls the lift amount of the intake valve (15) according to engine operating conditions.
0) - An example is shown. In Figures 7 and 8, (21
+ is a pulp drive cam, and this pulp drive cam (21
1 is constructed integrally with a cam shirt tonneau. (23)
23j is a rocker arm bent in the shape of (), and the lower surface of one end of this rocker arm (23j) is connected to the cam (21).
The lower surface of the other end is the stem end (
15b) respectively. Rocker arm (23
) is formed by smoothly curving with a predetermined curvature along its longitudinal direction, and this back surface (238)
A flat lower end surface (24a) of a reversible member extending in the longitudinal direction of the rocker arm (23) is in fulcrum contact with the rocker arm (23). A groove (c) is formed in the other end (end on the stem end (15b) side) of the lever (24), and a support shirt (261) is fitted into this groove (25). (Support shirt) (2 inch is fixed and supported by the cylinder head (11), and supports the lever (2 (a) in a swingable (tiltable) manner. That is, the swing fulcrum of the lever (24) is constituted by a support shaft t261, and this fulcrum is made finely adjustable by an adjustment screw (271).In addition, a pair of side plates (28aX28b) are provided on both sides of the free end of the lever (24) to attach the bolt t. ;7!1
1 It is fixed by CJOI and these side plates (
28aX281 protrudes downward in the figure in a substantially triangular shape and is positioned to sandwich the rocker arm (23). A vertical groove (31) that opens downward is formed in this protruding portion of the side plate (28aX231), and a holder (321 (33)) is installed in one side plate (28aX28b) at the - of this vertical groove (31). Further, a hole C (41) is formed in the bent portion of the rocker arm (23), and three support rods (3) approximately parallel to the camshaft (22+) are inserted into this hole C341. Support rod (351
Both ends of the are inserted into the above-mentioned upper and lower grooves (31), and the springs (36
) is always urged downward (toward cam (2I)). Therefore, the spring (361 + support rod (3)
5), one end of the rocker arm (23) is connected to the cam (
21) and supports the rocker arm (23+).These levers (24) and side plates (28a) (28b)
) is provided with a control shaft (38) extending substantially parallel to the camshaft (22) and the support shaft (26); A control cam C39) that abuts on the upper end surface (24b) of is fixed. As shown in FIG. 12, a hydraulic actuator (40) is provided at the end of the control shaft (38), and the rotation of this hydraulic actuator is controlled by a switching valve (41). , control unit depending on the engine operating conditions) (
42) switches the electromagnetic switching valve (41), and high pressure oil from the hydraulic pump (4) is transferred to the hydraulic actuator (4 (1).
As a result, the inclination angle of the lever (2 (a)) is changed by the control cam (3!11).By changing this inclination angle, the The moving distance of the rocker arm (2:1 swing fulcrum) changes, and the lift amount of the intake valve (15) changes.

In addition, in Fig. 7 (h+l C"+2 bz intake valve (
15) is the valve spring; Figure 12 6; 3) is the oil pan.

Next, the effect will be explained.

When the engine starts, the valve drive cam (21) rotates,
Swing the rocker arm (23) and open the intake valve (15).
Drives opening and closing. In this case, the control unit (421 is the engine speed) is based on signals such as engine operating conditions, such as rotational speed, intake air amount, and engine temperature.

By determining the load condition and controlling the hydraulic pressure of the hydraulic actuator (40) appropriately by switching the electromagnetic switching valve (4υ), the control shaft is rotated to control the intake valve (
15) Control the lift amount. That is, control cam 09
) by changing the amount by which the lever (24) is pressed down, and by changing the distance that the fulcrum moves along the lower end surface (24a) of the lever (24) when the rocker arm (23) swings, the intake valve (151 The amount of lift is variably controlled.

Fig. 9 shows the case where the lift amount (Ll) of the intake valve (15) is small, Fig. 10 shows the case where the lift amount (L2) is large, and Fig. 11 shows the case where the lift amount (L2) of the intake valve (15) is large.
The valve lift characteristics according to Ll)(1''2) are shown by curves (aiXa2), respectively. When the engine is operating at low speed and low load (e.g. 40 Icm/cm from idling state)
(during city driving up to steady driving state),
As shown in FIG. 9, the hydraulic actuator (40) rotates the control cam (39) to control the amount by which the lever (2 (a) is pressed down). As a result, the rocker arm (23
), its back surface (23a) is the lever (24).
), the rocker arm (23) moves a predetermined distance from the other end toward one end of the rocker arm (23) while making fulcrum contact with the lower end surface (24a) of the rocker arm (23), and the moving distance is small. It swings to push down the intake valve (15) by a predetermined value (1)1). At this time, the intake valve (151) is lowered to the position shown by the imaginary line (11) in FIG. will be generated.

On the other hand, during high-speed, high-load operation of the engine, as shown in FIG. 10, the control unit (421) causes the hydraulic actuator (40) to rotate the control cam (39) by a prescribed angle, thereby causing As a result, the rocker arm (23), which is driven by the valve drive cam (21) and swings, has a swing fulcrum that extends from the other end of the arm (23j to the vicinity of the bending part). The stem end (15b) of the intake valve (15) is moved to a predetermined value (L) at the other end as shown by the imaginary line in the figure.
2) Press down (1□2) L, ). Therefore, the intake valve (15) descends to the position indicated by the imaginary line (e) in FIG. 5, opens the intake bow 1:3, and fills the cylinder (12) with intake air. In this case, the shroud wall (I[il height and protrusion amount to the cylinder (12))
+1-11 is extremely small compared to the lift amount (L2) (■, 2ki 211), so the shroud wall (I f
il acts as a small intake resistance and the cylinder (12)
The intake air filling efficiency has been improved.

Furthermore, in this case, since the shroud wall (16) is low, the intake air vortex within the cylinder (12) does not become excessive.

Next, with reference to FIG. 13, we will explain the possibility of thinning the air-fuel ratio or the required recirculation ratio of exhaust gas (for reducing NOx) when the device generates a vortex in the intake air. Figure 13 shows the air-fuel ratio on the horizontal axis, the exhaust recirculation ratio on the vertical axis, and the fuel consumption rate at partial load (for an engine with 4 cylinders and a displacement of 1.87) when the fuel consumption rate is taken as a parameter. Q
Performance characteristics during steady running at k/n/h) are shown.

Curves (light) (+) 2) and (b3) in the figure indicate equal fuel consumption rate curves, and the fuel consumption rate increases as the air-fuel ratio increases (
As the exhaust gas recirculation ratio becomes smaller, there is a tendency for it to improve as the exhaust gas recirculation ratio becomes smaller, as shown by the arrow in the figure. In addition, the dashed-dotted line IC+ in the figure is the emission limit of N(,)x, that is, NO
This shows the limit to which x emissions can be suppressed to the regulation value level.

Additionally, in general, leaner air-fuel ratios and increased exhaust recirculation ratios make combustion unstable, but the stability limit for engine combustion is indicated by the broken line (
It is shown in (1). According to this, when the air-fuel ratio is 19, combustion is stabilized with exhaust gas recirculation of 20% or less. From the above results, the practical operating range is defined as "l+ N(-)X emission limit (the part surrounded by C1 and combustion stability limit (d+)" in the figure
From this, the part with a good fuel consumption rate (the part surrounded by (1), (%
) The range is as follows. The zone (Xi) exhibiting the best fuel efficiency is a characteristic that appears in most cases during partial load operation in the practical operating range. Therefore, using the intake vortex generation device, In addition, the exhaust recirculation ratio is in the range of 16% or less (practical fuel efficiency is significantly improved by operating with Xi).The two-dot chain line tel in the figure indicates the stability of combustion in a conventional engine that does not use this device. According to this, the best fuel efficiency zone is extremely small, and there are
It is understood that one roll is almost impossible.

Further, FIGS. 14 to 17 show other embodiments of the present invention. In this embodiment, the umbrella portion (
+53), as shown in FIG. Also, 1st, 6th, 17th
As shown in the figure, the stem end of the intake valve (15) (
]5+))) and form a recess (15C) in the recess (15C).
An alignment screw (54) is screwed into the end of the rocker arm +231 that abuts the rocker arm (J, 5C). As a result, the concave portions (1, 5C) prevent the intake valve (15) from raining once per rotation during one drive, and a vortex is generated in the intake air as shown by the arrow in FIG. 14. Other configurations and effects may be implemented as described above. 1] is the same as 7. ).

Furthermore, Fig. 1)(, 19 shows another embodiment of the variable valve lift mechanism). By changing the fulcrum position, the rocker ratio is changed and the lift amount of the intake valve (15) is controlled in accordance with the engine operating conditions.In this case, the amount of change in the rocker ratio is determined by the variable valve lift described in 2. Although it is smaller than the mechanism (201), the effects of the present invention can be achieved in the same way.Even in this case, the shroud (53) of a predetermined height is used as a vortex generating member to serve as an umbrella for the intake valve (15). (15a).

As explained below, the present invention includes an intake valve that opens and closes an intake boat of a cylinder, and a vortex flow generating member that is provided on the intake boat or the intake valve and generates a vortex flow of intake air within the cylinder. , a variable valve lift mechanism that variably controls the lift amount of the intake valve according to engine operating conditions; During operation, the lift amount of the intake valve is controlled to be small, resulting in high speed.

The internal combustion engine's intake vortex generating device controls the reflux (ref during high-load operation) and thicker shadows, making it possible to simply generate the optimum intake vortex over the entire range from low-speed, low-load operation to high-speed, high-load operation. In addition to this, it is also possible to fill intake air with high efficiency during high-speed, high-load operation. the result,
When the engine is running at low speeds and with low load, sufficient intake swirl allows for lean combustion, which improves fuel efficiency and improves fuel efficiency.
high speed.

During high-load operation, intake air inflow resistance can be reduced, intake air charging efficiency can be improved, and combustion stability can be ensured by preventing misfires.

4 Simplification of drawings) λ/3 "Explanation Figure 1 is a bottom view of the cylinder head showing a conventional intake vortex generating device for an internal combustion engine, and Figure 2 is a diagram showing the I'l- of Figure 1.
3 is a sectional view taken along arrow II-111 in FIG. 2; FIG. 4 is a bottom view of a cylinder head showing an embodiment of the intake vortex generation device for an internal combustion engine according to the present invention;
Figures 5 and 6 are V-V and Vl in Figure 4, respectively.
-Vl arrow sectional view, FIG. 7 is a partially cutaway front sectional view of the variable valve lift mechanism in the device, FIG. 8 is a general plan view of the mechanism, and FIGS. 9 and 10 are the mechanism. Fig. 11 is a diagram showing the lift characteristics of the intake pulp, Fig. 12 shows the hydraulic actuator in the mechanism, fat is a schematic overall view thereof, and Fig. 11 is a plan view thereof;
FIG. 13 is a graph showing the relationship between the air-fuel ratio and the exhaust gas recirculation ratio of an internal combustion engine using the device, and FIG. 14 is a bottom view of the cylinder head of another embodiment of the present invention.
Figure 15 is a cross-sectional view taken along arrows xv-xv in Figure 14;
FIG. 17 is a schematic front sectional view showing the stem end of the intake valve of the device, FIG. 17 is a schematic front sectional view thereof, and FIG.
FIG. 19 is an enlarged view of the intake pulp of the mechanism.

(12)... Cylinder (!3)... Intake boat (I5)... Intake valve f161 (53)... Whirlpool generation member (Nyuroud)
(2 (11 (in)... Variable valve lift mechanism patent applicant 1) San Jidosha Co., Ltd. Representative Patent attorney
Our military - Department Figure 1 Figure 2 Figure 3 Figure 4 Figure 8 Figure 9 Figure 10 Figure 11 Frank's own ship □ Figure 16 Figure 18 Figure 7q Procedure amendment (Own ship 1982) September 1 Patent Application No. 57-117086 2, Name of the invention Intake vortex generation device for internal combustion engine 3, Relationship with the case of the person making the amendment Patent applicant Address 2, Takaracho, Kanayō-ku, Yokohama-shi, Kanagawa Prefecture Name
(399) Nissan Motor Co., Ltd. 4, Agent 151 Address 2nd Tanaka Building, 2-6-9 Yoyogi, Shibuya-ku, Tokyo Name Patent attorney (7260) Armed Forces Partial Phone number 370-2470 5.? ! In the "Detailed Description of the Invention" column of the correct subject specification, "Drawing 6, Contents of Amendment + 11 The following sentence is added between page 14, line 9 and line 10 of the specification.

[Furthermore, FIGS. 20 and 21 show still another embodiment of the present invention. Similar to the previous embodiments (the embodiments shown in FIGS. 4 to 13), this embodiment has a vortex generating member installed at a predetermined height H (intake valve) 5 at the opening end of the intake boat 13, approximately equal to the maximum lift amount of the intake boat 13. %) of the shroud wall 16.

Other than that, the configuration of the variable valve lift mechanism 20 is the same, and the explanation thereof will be omitted. In addition, 71 in the figure is the intake port [
34 connected intake pipes are shown, and a fuel injection nozzle 72 is attached to this intake pipe 71 for injecting fuel toward the vicinity of the intake boat 13 in synchronization with the opening and closing of the intake valve 15. Further, the fuel injection nozzle 72 is driven and controlled by a drive current from the control unit 42. That is, this control unit 42 controls the engine intake air amount,
The operating conditions of the engine are determined based on various input signals such as engine speed, crank angle, and water temperature, and the fuel injection nozzle 72 is controlled according to the operating conditions. Further, in the figure, 73 is a spark plug attached to the cylinder 11.

Therefore, the operation of the above embodiment is similar to that of the embodiment shown in FIGS. is controlled to be small (approximately 2 times the maximum lift amount) (this valve lift variable means 20
The operation is the same as in the previous embodiment. ). As a result, the shroud wall 16 and the intake valve 15 generate an intake swirl flow within the combustion chamber 12 during the intake stroke. This intake swirl flow is a swirl flow along the side wall of the cylinder hole within the combustion chamber 12, and the velocity component of this swirl flow in the axial direction of the cylinder hole is small. From this, it can be seen that if only air is taken in from the intake bow [3] at the beginning of the intake stroke, and if fuel is injected at the later stage, a swirl flow of the mixture of fuel and air will be formed in the upper part of the combustion chamber 12. Become. That is, in the combustion chamber 12, there is a thin fuel mixture layer at the bottom,
Approximately two layers of fuel-rich mixture layer are separated and formed at the top.

As a result, the vicinity of the spark plug 73 is filled with a rich air-fuel mixture at the end of the compression stroke, and overall good ignition performance can be ensured in a lean fuel-air mixture state (lean combustion is possible).

On the other hand, during high-load operation, the intake valve 15 is lifted to near the maximum lift amount, and the shroud wall 16 and the umbrella portion of the intake valve 15 are separated from each other by a large distance. Therefore, combustion chamber 1
2, almost no intake swirl flow is generated,
A mixture of air and fuel is generated throughout the combustion chamber 12.

As a result, the air utilization rate is improved, and the spark plug 73
An optimal air-fuel mixture can always be generated in the vicinity of .

Further, at this time, the shroud wall 16 does not act as a resistance to intake air into the combustion chamber 12, and the efficiency with which intake air is filled into the combustion chamber 12 is significantly increased. ” (2) On page 16, line 12, “This is an enlarged view.
20 shows still another embodiment of the present invention, and FIG. 21 is a bottom view of the cylinder head thereof, and FIG. 21 is a schematic vertical sectional view of the cylinder head. ” he corrected.

(3) Supplement the drawings (Figures 20 and 21) as shown in the attached sheet.

that's all Figure 20

Claims (1)

[Claims] An intake valve that opens and closes the intake boat of the cylinder, a vortex generation member that is installed on the intake boat or the intake valve and generates a vortex of intake air in the cylinder, and a rift I of the intake valve.
- A variable valve lift mechanism that variably controls the turbulence according to engine operating conditions; controlling the lift t of the intake valve to be small to generate a strong intake vortex in the cylinder by the vortex generating member;
An internal combustion engine characterized in that during high-speed, high-load operation of the engine, the lift amount of the intake valve is controlled to be greater than the height of the vortex generating part to increase the filling efficiency of intake air into the cylinder. intake vortex generator.