Intake arrangement for combustion chamber

Abstract

An intake arrangement for a cylindrical combustion chamber (40), comprising first (42) and second (44) intake ports, the arrangement being configured such that the first port (42) generates a rotary flow (52) in the space and the second port (44) generates a flow having first (54) and second (55) components, the first component (54) being directed axially into the space and the second component (55) generating a rotary flow in the space, the rotary flow generated by the first port (42) and the second component (55) having the same sense of rotation, the second port (44) comprising a first branch (76) having a first end arranged to open into the combustion chamber (40) and a second end connected to a second branch (72), the second branch (72) extending transversely to the first branch (76), the connection (74) of the first and second branches (76, 72) is configured such thatthat it has an outer partially cylindrical wall (80) with a longitudinal axis parallel to the longitudinal axis of the combustion chamber (40) and an inner partially cylindrical wall (82) coaxial with the outer wall (80).

Description

[0001] The present invention relates to an intake arrangement for a combustion chamber and, in particular, to an intake port configuration for a combustion chamber of a direct injection diesel engine.

[0002] An important aspect of designing a combustion chamber or cylinder and its associated ports is the creation of an efficient internal motion field in the form of an axial vortex, known as "swirl." An efficient design generates high swirl to enable rapid distribution of the air or fuel-air mixture throughout the chamber, resulting in efficient combustion.

[0003] Another design criterion is the flow coefficient, a measure of mass flow rates from a port or the permeability of the space, which represents the efficiency with which the intake ports fill the space with air or fuel-air mixture. This is also known as gas exchange.

[0004] In known four-cylinder engines, the filling efficiency is increased by providing two intake ports or ports for each cylinder. The design of the ports varies. One is configured to have a high swirl value, and the other is configured to have a high degree of permeability. A problem with such an arrangement is that the high-permeability port provides an opposing swirl vortex, resulting in a reduction in the overall swirl value. One previously proposed solution is the installation of a swirl flap near one port for the purpose of generating the desired swirl value and thus the desired combination efficiency. However, the use of a swirl flap necessarily results in a loss of filling efficiency.

[0005] US 4,760,821 A describes an intake port designed as a filling port for each cylinder, in which a flap valve is located rotating about an axis. During full-load operation, the flap valve is in a rest position that does not affect the flow through the intake port. During partial-load operation, however, the flap valve is in an operating position in which it shapes the flow in the intake port so asymmetrically that the compressed air flowing out in large quantities at the opening of the intake port into the cylinder tends toward spiral and / or turbulence-enhancing directions.

[0006] JP S58-197420 A describes an intake port with a Siamese connection and its branching point inside a cylinder head. One main intake port with a larger passage area between two intake ports is helically shaped, and the other auxiliary intake port is straight. A branching point between two intake ports is located inside a cylinder head, and both ports are designed as Siamese ports. A cylinder head is equipped with a cylinder head cavity in which a main combustion chamber is located. The flow flowing through the main intake port generates swirl in the combustion chamber due to the helical shape. In the high-speed range, the helical shape causes the flow resistance and the flow rate of the auxiliary intake port to ensure charging efficiency and power.

[0007] US 7 707 989 B2 describes an engine combustion chamber having a first intake port formed from a straight port, a throat portion formed in a linear shape and opening in a tangential direction of the inner circumference of a cylinder, thereby generating a first swirl, and a second intake port formed from a helical port with a throat portion formed in a helical shape, thereby generating a second swirl within the first swirl in the same direction as that of the first swirl.

[0008] The object of the present invention is to provide improved internal air movement. The invention also aims to provide an intake arrangement with improved filling efficiency.

[0009] According to the invention, an intake arrangement for a generally cylindrical combustion chamber is provided, comprising first and second intake ports, the arrangement being configured such that the first port generates a substantially rotary flow in the space and the second port generates a flow having first and second components, the first component being directed substantially axially into the space and the second component generating a substantially rotary flow in the space, the rotary flow generated by the first port and the second component having the same sense of rotation.The second channel comprises a first branch having a first end arranged to open into the combustion chamber and a second end connected to a second branch, the second branch extending transversely to the first branch, the junction of the first and second branches being configured to have an outer part-cylindrical wall having a longitudinal axis substantially parallel to the longitudinal axis of the combustion chamber and an inner part-cylindrical wall substantially coaxial with the outer wall.

[0010] One advantage of the arrangement described above is the combination of high filling ratio with good flow distribution within the chamber. This allows for an increase in the power density of engines, especially modern diesel engines, without any deterioration in low-end torque. Thus, high performance and fuel economy are maintained.

[0011] An advantage of this arrangement is that an incoming longitudinal flow passes along the second branch between the outer wall and the inner wall to generate a rotational flow, which passes through the first branch to generate the substantially rotational flow of the second component in the space.

[0012] Preferably, the inner wall extends only within a part of the height of the outer wall remote from the combustion chamber.

[0013] Preferably, the inner and outer walls have cross-sections that form parts of circles.

[0014] Preferably, the part-circular section of the inner wall merges into a substantially straight section extending over the second branch.

[0015] An advantage of this arrangement is that the incoming flow along the second branch impinges on the substantially straight section and becomes a flow along the first branch to create the substantially axial flow of the first component into the chamber. Accordingly, there is no need to provide a wall in the first branch itself to separate the flows, thereby simplifying the casting and machining processes involved in the manufacture of the first branch.

[0016] The height of the substantially straight section may be taken away from the part-circular section of the inner wall.

[0017] In a preferred arrangement, at parts of the inner and outer walls remote from the second branch and from the combustion chamber, the inner and outer walls terminate and are connected by an end wall extending in a substantially vertical direction, the inner wall, the outer wall and the end wall forming an annular passage.

[0018] An advantage of this arrangement is that the configuration of the annular passage can assist in directing the rotational flow through the first branch and into the room.

[0019] In a preferred arrangement, a substantially cylindrical sub-chamber is formed adjacent to the combustion chamber, the sub-chamber being partially delimited by a part of the height of the outer wall adjacent to the combustion chamber.

[0020] An advantage of this arrangement is that the subspace provides a suitable path for the passage of the rotary and axial flows to the first branch.

[0021] Between the vertically extending end wall and the second branch, the outer wall may continue circumferentially in a radially recessed section which also partially delimits the subspace.

[0022] The top of the subspace may be defined by a plateau portion whose edge is defined by the lower end of the inner part-cylindrical wall and the upper end of the depressed portion of the outer cylindrical wall.

[0023] According to the invention, an intake duct arrangement for a combustion chamber is provided, comprising a first branch having a first end arranged to open into the combustion chamber and a second end connected to a second branch, the second branch extending transversely to the first branch, the junction of the first and second branches being configured to have an outer part-cylindrical wall with a longitudinal axis substantially parallel to the longitudinal axis of the first branch and an inner part-cylindrical wall substantially coaxial with the outer wall. The junction of the first branch and the second branch is designed to induce a flow having a vertical component and a rotational component.

[0024] An advantage of this arrangement is that it can produce a good flow distribution in an associated combustion chamber. Arrangements according to the second aspect can have the same preferred features as arrangements according to the first aspect and have the same advantages.

[0025] According to the invention, there is provided a combination of a combustion chamber and an intake configuration therefor, the intake configuration comprising an intake arrangement according to the first or second aspect of the present invention.

[0026] According to the invention, there is provided an automotive engine comprising the combination of a combustion chamber and an intake configuration therefor according to the third aspect of the present invention.

[0027] The engine may be a diesel engine, preferably a direct injection diesel engine.

[0028] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. Figure 1 is a schematic side view of a combustion chamber and associated intake and exhaust ports according to the prior art; Fig. 2 is an enlarged view, seen in a downward direction from the channels into the space according to Fig. 1; Fig. 3 a view according to Fig. 2 of a combustion chamber having an intake arrangement according to an embodiment of the present invention; Fig. 4 a plan view of the exterior of the intake assembly according to Fig. 3 is; Fig. 5 a perspective view of the arrangement according to Fig. 4 is; Fig. 6 an enlarged schematic view of an intake duct of the arrangement according to Fig. 3 is; Fig. 7 a side view of the intake duct according to Fig. 6 with the canal wall removed for clarity and Fig. 8, Fig. 9 and Fig. 10 perspective views showing the configuration of the exterior of the canal according to Fig. Show 6.

[0029] Referring to the drawings, Fig. 1 and Fig. 2 shows a prior art chamber or cylinder 10 of an internal combustion engine, in particular a direct-injection diesel engine. In its upper wall 32, the chamber has intake ducts or openings 12, 14 for air entry and exhaust openings 16, 18. As generally indicated by arrow 22, the first intake duct 12 creates a flow that is substantially tangential to the wall 30 of the chamber to generate high swirl. As generally indicated by arrow 24, the second intake duct 14 creates a flow that is primarily directed axially into the chamber. However, the flow has a non-negligible rotational or tangential component that creates a swirl vortex in the direction opposite to arrow 22 and thus leads to an overall reduction in the swirl value of the chamber, as indicated by arrow 28.

[0030] Fig. 3, Fig. 4 and Fig. 5 show a combustion chamber 40 according to an embodiment of the present invention. An upper wall 62 of the chamber has intake ports or openings 42, 44 and exhaust ports 46, 48. A first intake port 42 is intake port 12 of the chamber according to Fig. 1 and Fig. 2 and creates a rotational flow as indicated by arrow 52.

[0031] As indicated by arrows 54 and 55, the flow of air exiting the second intake duct 44 is split into two major components. Thus, the intake duct 44 can be considered a hybrid duct. A first component, represented by arrow 54, is directed substantially axially into the space 40. This achieves efficient flow into the space by increasing the flow coefficient and permeability. A second component, represented by arrow 55, introduces a swirl into the space 40 that has the same sense of rotation as the first flow component 54 and thus contributes to the overall rotational movement in the space.

[0032] The enlarged sectional and side views of intake duct 44 shown in Fig. 6 and Fig. 7 illustrate that the channel or orifice is divided by a plane 60 into two semi-cylindrical passages 64 and 68. It should be emphasized that plane 60 is not an actual physical barrier, but rather a virtual plane indicating the differences between the relatively axial flows 54a to 54d from region 64 and the relatively rotational flow 55 from region 68. By appropriately configuring the intake channel 44, and particularly the region thereof near its orifice opening into the space 40, flows 54 and 55 can be generated simultaneously without compromising the factors of flow coefficient and swirl generation. The two flows are generated before they pass through the valve opening into the space.

[0033] Fig. 8, Fig. 9 and Fig. 10 show perspective views of the exterior of intake duct 44 with branches or passages 72, 76. A passage 72, which, when installed, extends with a slight downward slope, is connected at a connecting region or elbow 74 to a shorter passage 76 arranged to open into the space 40. The configuration of the connecting region 74 is arranged to produce the two-component flow referred to above.

[0034] Channel 44 includes an outer, generally cylindrical wall 80. Radially inwardly spaced from wall 80 is an inner, partially cylindrical wall 82. Walls 80 and 82 are connected at the top by a partially circular wall 84. Walls 80, 82, 84 define an annular passage 106 between them for generating the rotational flow components (indicated by arrow 55) in space 40.

[0035] Inner wall 82 extends vertically downward from wall 84 by a distance "d," which is only a fraction of the height "h" of outer cylindrical wall 80. At one end, wall 82 merges into a wall portion 90 having a height "D" where it meets wall 92 of passage 72: (where D > d). The effect of the flow within passage 72 is to impinge on the interior of wall 90 and the adjacent portion of wall 82, creating the axial or vertical flow component (indicated by arrow 54) in space 40.

[0036] The part-circular space formed within walls 80, 82 and 84 terminates in a substantially vertical wall section 94. Thus, it can be seen that there is a circumferential gap between walls 92 and 94 towards the front of the channel, ie in the direction of the viewer in Fig.8 to 10. Visible through the gap is a partially cylindrical wall 100, slightly depressed compared to wall 80, and a plateau region 102 forming the top of a generally cylindrical subspace 108 within the channel. Subspace 108 is formed by walls 80, 100. The edge of plateau region 102 is formed at the rear by the lower edge of wall 82 and at the front by the upper edge of wall 100.

[0037] It is through subspace 108 that the rotary and axial flows 55 and 54 are transferred to space 40.

[0038] An advantage of the above-described embodiment is the combination of high filling ratio with good air distribution within the chamber. This allows for an increase in the power density of engines, particularly modern diesel engines, without any deterioration in low-end torque. Thus, high performance and fuel economy are achieved. The configuration of the intake ducts 44 without the need for a separating wall in the plane 60 simplifies the casting and machining processes. However, if desired, an actual wall can be provided in a modification.

[0039] The relative contours and sizes of the walls and channel sections 80, 82, 84, 92, 94, 100 and 102 are shown as an example and can be varied as desired.

[0040] In direct-injection diesel engines, only air passes through the intake ports. This intake arrangement can also be used in other engines where a fuel-air mixture passes through the ports. Reference symbol 10 combustion chamber, cylinder 12, 14 intake ducts or openings 16, 18 exhaust channels or openings 22, 24, 28 arrows 30, 32 room walls 40 combustion chamber 42, 44 intake ducts or openings 46, 48 exhaust ports or openings 52, 54 arrows 54a-54d axial flows 55 Arrow 60 level 62 upper room wall 64, 68 passages, regions 72 passage, canal branch 74 Connective region, knee 76 Passage, canal branch 80 outer wall 82 inner wall 84 upper wall 90 wall section 92 Wall 94 wall section 100 wall 102 Plateau region 106 annular passage 108 subspace

Claims

[1] Intake arrangement for a cylindrical combustion chamber (40), comprising first (42) and second (44) intake ports, the arrangement being configured such that the first port (42) generates a rotary flow (52) in the space and the second port (44) generates a flow having first (54) and second (55) components, the first component (54) being directed axially into the space and the second component (55) generating a rotary flow in the space, the rotary flow generated by the first port (42) and the second component (55) having the same sense of rotation, the second port (44) comprising a first branch (76) having a first end arranged to open into the combustion chamber (40) and a second end connected to a second branch (72), the second branch (72) extending transversely to the first branch (76), the connection (74) of the first and second branches (76, 72) is configured such thatthat it has an outer partially cylindrical wall (80) with a longitudinal axis parallel to the longitudinal axis of the combustion chamber (40) and an inner partially cylindrical wall (82) coaxial with the outer wall (80). [2] Intake arrangement according to claim 1, wherein the inner wall (82) extends only within a part of the height (h) of the outer wall (80) remote from the combustion chamber (40). [3] An intake assembly according to claim 1 or 2, wherein the inner (82) and outer (80) walls have cross-sections forming parts of circles. [4] Intake arrangement according to claim 3, wherein the part-circular section of the inner wall (82) merges into a straight section (90) which extends beyond the second branch (72). [5] An intake assembly according to claim 4, wherein the height of the straight portion (90) increases away from the part-circular portion of the inner wall (82). [6] An intake arrangement according to any one of claims 2 to 5, wherein at portions of the inner (82) and outer (80) walls remote from the second branch (72) and remote from the combustion chamber (40), the inner and outer walls terminate and are connected by an end wall (94) extending in a vertical direction, the inner wall (82), the outer wall (80) and the end wall (94) forming an annular passage (106). [7] Intake arrangement according to any one of claims 2 to 5, wherein a cylindrical sub-chamber (108) is formed adjacent to the combustion chamber (40), the sub-chamber (108) being partially bounded by a part of the height of the outer wall (80) adjacent to the combustion chamber (40). [8] Intake arrangement according to claim 7, wherein between the vertically extending end wall (94) and the second branch (72) the outer wall (80) continues circumferentially in a radially recessed section (100) which also partially delimits the sub-chamber (108). [9] Intake arrangement according to claim 7 or 8, wherein the upper side of the sub-chamber (108) is defined by a plateau portion (102) whose edge is defined by the lower end of the inner part-cylindrical wall (82) and the upper end of the recessed portion (100) of the outer cylindrical wall (80). [10] Intake duct arrangement for a combustion chamber (40), comprising a first branch (76) having a first end arranged to open into the combustion chamber (40) and a second end connected to a second branch (72), the second branch (72) extending transversely to the first branch (76), the junction (74) of the first and second branches (76, 72) being configured to have an outer part-cylindrical wall (80) with a longitudinal axis parallel to the longitudinal axis of the first branch (76) and an inner part-cylindrical wall (82) coaxial with the outer wall (80), the junction (74) of the first branch (76) and the second branch (72) being designed to induce a flow having a vertical component (54) and a rotational component (55). [11] A combination of a combustion chamber (40) and an intake configuration therefor, wherein the intake configuration comprises an intake arrangement according to any one of the preceding claims 1 to 9. [12] A motor vehicle engine comprising the combination of a combustion chamber (40) and an intake configuration therefor according to claim 11. [13] A motor vehicle engine according to claim 12, which is a diesel engine. [14] A motor vehicle engine according to claim 13, which is a direct injection diesel engine.

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