JP5630435B2 - cylinder head - Google Patents

Description

  The present invention relates to a cylinder head having an exhaust port for each cylinder of an internal combustion engine.

  A cylinder head used in a multi-cylinder internal combustion engine (engine) is provided with an exhaust port for guiding exhaust gas discharged from each cylinder to an exhaust passage.

  Recent multi-cylinder engines are configured to exhaust from one cylinder with two or more exhaust valves. Therefore, the exhaust port of the cylinder head is divided into a plurality of regions (upstream portions) from the upstream end to the downstream in the exhaust flow direction, and there is one region (downstream portion) from the middle to the downstream end. Are gathered.

  By the way, for example, Patent Literature 1 describes that ribs are provided on the inner peripheral surfaces of the intake port and the exhaust port on the upstream side of the valve stem. The rib is provided so that the valve stem does not become a resistance to intake and exhaust, and the intake and exhaust flow smoothly (see abstract, paragraph 0015).

  For example, Patent Document 2 describes that a plurality of fin-shaped portions are provided on the upper and lower portions of the inner peripheral surface of the exhaust port (see paragraphs 0033 and 0040). The fin-shaped portion is provided to recover the heat of the exhaust gas (see paragraphs 0034 and 0040).

JP-A-4-330352 Japanese Patent Laid-Open No. 10-317995

  The rib of the conventional example according to the above-mentioned Patent Document 1 is for smoothly flowing intake air and exhaust gas, and no technical idea for intentionally collecting the heat of the exhaust gas can be heard.

  In the conventional example according to Patent Document 2, it is considered that the exhaust gas heat cannot be recovered as efficiently as expected when the internal combustion engine rotates at high speed. This is because the fin-shaped portion shown in Patent Document 2 has a configuration in which a large number of small fins are arranged in a comb-teeth shape in the circumferential direction, so that the circumferentially opposed spaces of the fins adjacent to each other in the circumferential direction. Is extremely narrow. Moreover, the positions of the protruding ends of the fins adjacent in the circumferential direction are aligned in the circumferential direction. In such a configuration, when the flow rate of the exhaust gas is high as at the time of high rotation of the internal combustion engine, it becomes difficult for the exhaust gas to enter the circumferentially opposed spaces of the respective fins adjacent in the circumferential direction. Although the exhaust gas touches the protruding ends of the fins, it is thought that it becomes difficult to touch both side surfaces of the fins.

  In view of such circumstances, an object of the present invention is to make it possible to efficiently recover the heat of exhaust gas when the internal combustion engine rotates at high speed in a cylinder head having an exhaust port for each cylinder of the internal combustion engine.

  The present invention is a cylinder head having an exhaust port for each cylinder of an internal combustion engine, wherein an upstream portion of the exhaust port extends from the cylinder in a direction inclined with respect to a central axis of the cylinder. A plurality of exhaust gas passages are provided for each, and the downstream portion of the exhaust port is an exhaust gas passage where the plurality of upstream portions gather on the downstream side in the exhaust flow direction, from the upstream portion to the downstream portion In the inner peripheral surface of the cylinder, in the region on the top dead center side in the central axis direction of the cylinder, the same number of elongated protrusions as the upstream portion protrude toward the bottom dead center side in the central axis direction of the cylinder. And is provided so as to extend in the exhaust flow direction, and is located on the inner peripheral surface of the downstream portion in the region of the top dead center side in the central axis direction of the cylinder and sandwiched between the plurality of protrusions, The short ridge is the bottom dead center in the direction of the central axis of the cylinder. Projecting in the direction of exhaust flow and extending in the exhaust flow direction, the amount of protrusion in the upstream region of the short ridge is smaller than the amount of protrusion in the region other than the upstream region. It is characterized by being set.

  In short, in the present invention, in addition to the same number of the elongated ridges as the plurality of upstream portions of the exhaust port, the short ridges are provided, so that the entire surface area of the exhaust port (for recovering the heat of the exhaust gas) The surface area) is made as large as possible, and the present invention is devised to eliminate the concern caused by the provision of the short protrusion.

  That is, in the above-described configuration, the short ridge portion is devised so as to reduce the amount of protrusion in the upstream region of the exhaust port, so that it is downstream from a plurality of upstream portions of the exhaust port, particularly at a high speed of the internal combustion engine. When the exhaust gas flowing into the part at high speed collides with the upstream region of the short ridge part, the exhaust gas is difficult to disperse.

  As a result, the flow rate of the exhaust gas is unlikely to slow down. In other words, since the exhaust gas is maintained at a high flow rate and flows smoothly from a plurality of upstream portions of the exhaust port to the most downstream of the downstream portion, for example, the protrusion amount in the upstream region of the short ridge portion As compared with the case where the is substantially constant, the heat of the exhaust gas can be efficiently moved (transmitted) to the short ridge portion and the downstream region of the plurality of long ridge portions. Therefore, when the internal combustion engine is rotating at high speed, the heat recovery of the exhaust gas at the downstream portion of the exhaust port is efficiently performed, and as a result, the exhaust gas cooling performance is improved.

  Preferably, the upstream region of the short ridge portion may be configured such that the amount of protrusion gradually increases from the upstream end toward the downstream side.

  Here, in short, the ridgeline in the upstream region of the short ridge is inclined with respect to the flow direction of the exhaust gas (or the central axis of the downstream portion), thereby protruding in the upstream region of the short ridge. The amount is set to be smaller than the protruding amount in the region other than the upstream region.

  In this case, the exhaust gas flowing at a high speed from the plurality of upstream portions to the downstream portion of the exhaust port particularly during high rotation of the internal combustion engine is less likely to be dispersed when colliding with the upstream region of the short ridge portion. The gas flow rate is unlikely to slow down.

  Preferably, the short ridge portion may be configured to be provided starting from a position away from the position of the upstream end (aggregation starting point) in the downstream portion of the exhaust port.

  Here, in short, the position of the upstream end of the short ridge is retracted downstream, so that the amount of protrusion in the upstream region of the short ridge becomes the amount of protrusion in the region other than the upstream region. It is set to be less than that.

  Preferably, the connecting portion between the upstream end of the short ridge portion and the inner peripheral surface of the downstream portion of the exhaust port may have a curved shape so as to be smoothly connected.

  In this case, since the connecting portion between the upstream end of the short protrusion and the inner peripheral surface of the downstream portion of the exhaust port is not square, for example, when casting a cylinder head, stress concentration on the connecting portion can be avoided. It becomes possible to improve manufacturing yield and durability.

  The cylinder head according to the present invention can efficiently recover the heat of the exhaust gas particularly when the internal combustion engine is rotating at high speed, and can contribute to the improvement of the exhaust gas cooling performance.

FIG. 3 is a schematic plan view mainly illustrating an exhaust port in an embodiment of a cylinder head according to the present invention. It is an arrow view of the (2)-(2) line cross section of FIG. It is an arrow view of the (3)-(3) line cross section of FIG. It is a figure which expands and shows a part of FIG. It is the schematic diagram of the plane which described mainly the exhaust port in other embodiment of the cylinder head which concerns on this invention. FIG. 6 is a cross sectional view taken along line (6)-(6) in FIG. 5. FIG. 6 is a cross-sectional view taken along line (7)-(7) in FIG. 5. It is a figure which expands and shows a part of FIG.

  BEST MODE FOR CARRYING OUT THE INVENTION Best modes for carrying out the present invention will be described in detail below with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. In the figure, reference numeral 1 denotes an entire cylinder head of an internal combustion engine (engine). The internal combustion engine using the cylinder head exemplified in this embodiment is of a type using two intake valves and two exhaust valves, although not shown, in one cylinder 2. FIG. 2 shows one intake valve 21 and one exhaust valve 22.

  A recess 1 a for creating a combustion chamber 4 in cooperation with the cylinder 2 and the piston 3 is provided at a position corresponding to the cylinder 2 of the cylinder block (not shown) on the lower surface of the cylinder head 1. An intake port 5 and an exhaust port 6 are connected in communication with the recess 1a.

  As shown in FIG. 1, the exhaust port 6 includes a plurality (two in this embodiment) of upstream portions 6a and 6b and one downstream portion 6c. The upstream portions 6 a and 6 b are exhaust gas passages provided in plural for each cylinder 2 so as to extend from the cylinder 2 in a direction inclined with respect to the central axis Y of the cylinder 2. The downstream part 6c is an exhaust gas passage in which a plurality of upstream parts 6a and 6b are gathered. The assembly origin (or branch origin) is denoted by reference numeral 6d.

  The upstream ends of the first upstream portion 6a and the second upstream portion 6b of the exhaust port 6 are connected in communication with the combustion chamber 4 of the internal combustion engine. On the other hand, the downstream end of one downstream portion 6 c of the exhaust port 6 is opened to the back surface 1 b of the cylinder head 1.

  In general, although not shown, an exhaust passage such as an exhaust pipe is attached to the downstream end of the downstream portion 6c of the exhaust port 6, and a catalyst for purifying exhaust gas is installed in the exhaust passage. The exhaust system includes the exhaust pipe and the catalyst.

  As shown in FIG. 2, the central axis X1 (X2) of the first upstream portion 6a (second upstream portion 6b) is inclined with respect to the central axis Y of the cylinder 2, and the central axis Z of the downstream portion 6c is The first upstream portion 6a (second upstream portion 6b) is inclined with respect to the central axis X1 (X2).

  The central axis X1 (X2) of the first upstream portion 6a (second upstream portion 6b) is a straight line connecting the center of the upstream opening of the exhaust port 6 and the center of the assembly starting point 6d. The central axis Z of the downstream portion 6c is a straight line connecting the center of the gathering start point 6d and the center of the downstream opening.

  The inclination angle β of the central axis Z of the downstream portion 6c with respect to the central axis Y of the cylinder 2 is the inclination of the central axis X1 (X2) of the first upstream portion 6a (second upstream portion 6b) with respect to the central axis Y of the cylinder 2. It is set smaller than the angle α.

  In the cylinder head 1 having such an exhaust port 6, the same number of first and second protrusions 7 and 8 as the first and second upstream portions 6 a and 6 b are provided on the inner peripheral surface of the exhaust port 6. .

  These first and second elongated ridges 7 and 8 are provided in regions where the exhaust gas is easily guided on the inner peripheral surfaces from the first and second upstream portions 6a and 6b to the downstream portion 6c. Specifically, the first and second elongated ridges 7 and 8 have a diameter in a region on the top dead center side in the central axis Y direction of the cylinder 2 on the inner peripheral surfaces of the first and second upstream portions 6a and 6b. It is provided so as to protrude inward in the direction (toward the bottom dead center side in the direction of the center axis Y of the cylinder 2).

  The first and second elongated protrusions 7 and 8 are set to have substantially the same protruding shape and protruding dimension, and the first and second upstream portions 6a and 6b are positioned closer to the collection start point 6d than the upstream end ( For example, it is provided so as to continuously extend from the installation position of the valve guide 11 to the downstream end of the downstream portion 6c.

  Specifically, the first and second elongated ridges 7 and 8 are provided along the central axes X1 and X2 (or the exhaust flow direction) in the first and second upstream portions 6a and 6b. Further, the downstream portion 6c is provided so as to be substantially parallel to each other.

  In this embodiment, the exhaust gas cooling performance is improved by increasing the amount of heat transferred from the exhaust gas to the exhaust port 6 as much as possible at the time of high rotation of the internal combustion engine.

  Specifically, a short ridge 9 is provided on the inner peripheral surface of the downstream portion 6 c of the exhaust port 6. The short ridge portion 9 is a region on the top dead center side in the central axis Y direction of the cylinder 2 on the inner peripheral surface of the downstream portion 6c and the center in the circumferential direction, that is, the first and second long ridge portions 7, 8. Is provided so as to protrude inward in the radial direction (toward the bottom dead center side in the direction of the central axis Y of the cylinder 2).

  The short ridge portion 9 is provided substantially linearly along the central axis Z (or the exhaust flow direction) of the downstream portion 6c, and is shorter than the first and second long ridge portions 7, 8. Yes.

  And the protrusion amount in the upstream area (area near the collection start point 6d of the exhaust port 6) of the short protrusion 9 is set smaller than the protrusion amount in the area other than the upstream area. In this embodiment, the upstream region of the short ridge 9 is set so that the amount of protrusion gradually increases from the upstream end toward the downstream side.

  Thereby, the ridgeline in the upstream region of the short ridge 9 is inclined with respect to the flow direction of the exhaust gas (or the central axis of the downstream portion). In other words, the ridge line in the upstream region of the short ridge portion 9 is inclined with respect to the straight line 100 passing through the position where the protrusion amount is maximum in the upstream region and the radial center position of the assembly starting point 6d. ing.

  The inclination angle θ of the ridgeline in the upstream region of the short ridge 9 is set to an acute angle, for example. Incidentally, when the inclination angle θ is set to an obtuse angle, when the exhaust gas flows into the downstream portion 6c from the first and second upstream portions 6a and 6b, the exhaust gas collides with the upstream region of the short ridge 9. Then, since it is thought that it will become easy to disperse | distribute, it is not preferable.

  Furthermore, as shown in FIG. 4, the connecting portion 9a between the upstream end of the short ridge portion 9 and the inner peripheral surface of the downstream portion 6c has a curved surface shape (R shape) so as to be smoothly connected.

  With this configuration, the exhaust gas flowing at a high speed from the first and second upstream portions 6a and 6b of the exhaust port 6 to the downstream portion 6c particularly when the internal combustion engine is rotating at high speed is an upstream region of the short protrusion 9. Since it becomes difficult to disperse when it collides with the gas, the flow rate of the exhaust gas does not have to be slow in the downstream portion 6c.

  In other words, since the exhaust gas is maintained at a high flow rate from the first and second upstream portions 6a and 6b of the exhaust port 6 to the most downstream of the downstream portion 6c, and flows smoothly, the heat of the exhaust gas is reduced. It is possible to efficiently move (transmit) the short ridge portion 9 and the downstream region of the first and second long ridge portions 7 and 8.

  The reason will be explained. In general, the amount of heat (Q) transferred from the exhaust gas to the ridges (first and second long ridges 7, 8 and short ridges 9) is the heat transfer coefficient (α) of the ridges. The surface area (S) of the ridge and the temperature difference (ΔT) between the ridge and the exhaust gas are obtained (Q = α × S × ΔT). Here, it is not described as the amount of heat transferred in the exhaust port 6 as a whole, but is described as the amount of heat transferred (Q) of only the protrusion.

  In the first place, the heat transfer coefficient (α) is proportional to the flow rate of the exhaust gas.

  In general, when the internal combustion engine is running at a low speed, the flow rate of the exhaust gas flowing from the combustion chamber 4 of the internal combustion engine into the first and second upstream portions 6a and 6b of the exhaust port 6 is slow. The exhaust gas flow velocity is almost constant throughout the entire area. As a result, the heat transfer coefficient (α) at the time of the low rotation is substantially constant over the entire area from the upstream side to the downstream side of the first and second elongated protrusions 7 and 8.

  On the other hand, when the internal combustion engine is rotating at high speed, the flow rate of the exhaust gas flowing from the combustion chamber 4 of the internal combustion engine into the first and second upstream portions 6a and 6b of the exhaust port 6 is high. Here, if it is a case where the amount of protrusion in the upstream region of the short ridge portion 9 is substantially constant and not inclined, the first and second upstream portions 6a and 6b respectively flow into the downstream portion 6c at high speed. It is considered that the exhaust gas is dispersed by colliding with the upstream region of the short ridge 9 and the flow rate of the exhaust gas is reduced. Therefore, in such a case, it is considered that the transfer (transfer) of heat from the exhaust gas to the short protrusion 9 is reduced.

  In view of this, when the internal combustion engine is designed so as not to slow down the flow rate of the exhaust gas at the downstream portion 6c of the exhaust port 6 especially at the time of high rotation of the internal combustion engine, In this case, it can be said that the heat transfer coefficient (α) of the short ridge portion 9 does not have to be reduced.

  As described above, in the embodiment to which the present invention is applied, the exhaust gas flowing into the downstream portion 6c from the first and second upstream portions 6a and 6b at a high speed particularly in the high speed of the internal combustion engine It is devised to make it difficult to disperse when it collides with the upstream region.

  As a result, the exhaust gas is maintained at a high flow rate from the first and second upstream portions 6a, 6b of the exhaust port 6 to the most downstream side of the downstream portion 6c and flows smoothly. Compared with the case where the amount of protrusion in the upstream region of the gas turbine 9 is not made constant and inclined, the heat of the exhaust gas is reduced by the short ridge portion 9 and the first and second long ridge portions, particularly at the time of high rotation of the internal combustion engine. It is possible to efficiently move (transmit) the downstream area of the portions 7 and 8.

  Therefore, especially at the time of high rotation of the internal combustion engine, the heat recovery of the exhaust gas at the downstream portion 6c of the exhaust port 6 is efficiently performed, and as a result, the exhaust gas cooling performance is improved. Along with this, it becomes possible to suppress or prevent excessive temperature rise of the catalyst (not shown) at the time of high rotation of the internal combustion engine, so that it is possible to suppress deterioration of the function and durability of the catalyst over a long period of time. .

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) In the above embodiment, the cylinder head 1 used in a multi-cylinder internal combustion engine is taken as an example. However, the present invention is not limited to this, and is also applicable to, for example, a cylinder head used in a single cylinder internal combustion engine. Is possible. Even in this case, the exhaust port 6 has the same configuration as that of the above embodiment.

  (2) In the above embodiment, an example in which the connecting portion 9a between the upstream end of the short ridge portion 9 and the inner peripheral surface of the downstream portion 6c has a curved surface shape (R shape) so as to be smoothly connected is given. However, the present invention is not limited to this, and the present invention includes cases where such is not the case.

  (3) The short ridge portion 9 shown in the above embodiment is not particularly limited. For example, as to the shape of the short ridge 9, as shown in FIGS. 5 to 8, for example, a position 6 e that is separated from the position of the upstream end (aggregation starting point 6 d) in the downstream portion 6 c of the exhaust port 6 by a predetermined distance L. Can be provided as a starting point.

  In addition, about the shape of the elongate protrusion part 9, it is the same as that of the said embodiment. That is, the protrusion amount in the upstream region (region near the collection start point 6d of the exhaust port 6) of the short ridge portion 9 is set smaller than the protrusion amount in the region other than the upstream region. In this embodiment, the amount of protrusion in the upstream region of the short ridge 9 is set so as to gradually increase from the upstream end toward the downstream side. Thereby, the ridgeline of the upstream area | region of the elongate ridge part 9 inclines with respect to the flow direction of exhaust gas. In other words, the ridge line in the upstream region of the short ridge portion 9 is inclined with respect to the straight line 100 passing through the position where the protrusion amount is maximum in the upstream region and the radial center position of the assembly starting point 6d. ing. The inclination angle θ of the ridgeline in the upstream region of the short ridge 9 is set to an acute angle, for example.

  In this case, in short, since the short ridges 9 do not exist in the region where the exhaust port 6 is the gathering start point 6d, the first and second upstream portions are particularly at high revolutions of the internal combustion engine, as in the above-described embodiment. When the exhaust gas flows from the portions 6a and 6b into the downstream portion 6c at a high speed, even if the exhaust gas collides with the upstream region of the short ridge portion 9, it is difficult to be dispersed.

  As a result, the exhaust gas flow rate does not have to be slow. In other words, since the exhaust gas is maintained at a high flow rate from the first and second upstream portions 6a, 6b of the exhaust port 6 to the most downstream of the downstream portion 6c and flows smoothly, for example, a short ridge portion. Compared with the case where the amount of protrusion in the upstream region of the gas generator 9 is substantially constant, the heat of the exhaust gas is reduced by the short ridge portion 9 and the first and second long ridge portions 7, 8 can be efficiently moved (transmitted) to the downstream region.

  Therefore, particularly when the internal combustion engine is rotating at high speed, heat recovery of the exhaust gas at the downstream portion 6c of the exhaust port 6 can be performed efficiently, resulting in improved exhaust gas cooling performance. Further, since it is possible to suppress or prevent excessive temperature rise of the catalyst (not shown) at the time of high rotation of the internal combustion engine, it is possible to suppress deterioration of the function and durability of the catalyst over a long period of time.

  The present invention can be suitably used for a cylinder head having an exhaust port for each cylinder of an internal combustion engine.

1 Cylinder head
2-cylinder
6 Exhaust port
6a First upstream part of exhaust port
6b Second upstream part of exhaust port
6c Downstream part of exhaust port
6d Assembly origin (or branch origin)
7 1st long ridge
8 Second long ridge
9 Short ridge

Claims (4)

A cylinder head having an exhaust port for each cylinder of an internal combustion engine,
An upstream portion of the exhaust port is an exhaust gas passage provided in plural for each cylinder so as to extend from the cylinder in a direction inclined with respect to the central axis of the cylinder,
The downstream portion of the exhaust port is an exhaust gas flow path in which the plurality of upstream portions gather on the downstream side in the exhaust flow direction,
In the inner peripheral surface from the upstream portion to the downstream portion, the same number of elongated ridges as the upstream portion in the region of the top dead center side in the central axis direction of the cylinder is the bottom dead center in the central axis direction of the cylinder. Provided so as to protrude toward the side and to extend in the exhaust flow direction,
On the inner peripheral surface of the downstream portion, in the region on the top dead center side in the central axis direction of the cylinder and at a position sandwiched between the plurality of projecting strip portions, the short ridge portion is the bottom dead center in the central axis direction of the cylinder. Provided so as to protrude toward the side and to extend in the exhaust flow direction,
A cylinder head characterized in that a protruding amount in an upstream region of the short ridge is set smaller than a protruding amount in a region other than the upstream region. The cylinder head according to claim 1,
The cylinder head according to claim 1, wherein an amount of protrusion is gradually increased from the upstream end toward the downstream side of the upstream region of the short protrusion. The cylinder head according to claim 1 or 2,
The cylinder head according to claim 1, wherein the short ridge portion is provided starting from a position away from an upstream end (aggregation starting point) in a downstream portion of the exhaust port. The cylinder head according to any one of claims 1 to 3,
A cylinder head, wherein a connecting portion between an upstream end of the short ridge portion and an inner peripheral surface of a downstream portion of the exhaust port is formed in a curved shape so as to be smoothly connected.

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