JP2015063963A - Structure of cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder head having a structure capable of effectively improving manufacturing efficiency and processing accuracy.SOLUTION: In a structure of a cylinder head 4, on a cylinder body constituting ceiling parts 41 of combustion chambers of plural cylinders, a portion from the ceiling part to one side face part is a comparatively thin part 4, and a portion from the ceiling part to the other side face part is a comparatively thick part 4b. The structure comprises a cooling water passage 53 surrounding the plural ceiling parts 41, a thin side communication part 42a formed at the thin part, and opened to communicate the cooling water passage with a lower face side of the cylinder head body, and a thick side communication part 42b formed at the thick part, and opened to communicate the cooling water passage with the lower face side of the cylinder head body. An opening area of the thin side communication part is made smaller than that of the thick side communication part.

Description

  The present invention relates to a structure of a cylinder head constituting an internal combustion engine.

  In general, in a water-cooled internal combustion engine, a water jacket for circulating cooling water for cooling them is formed in a cylinder block and a cylinder head constituting the internal combustion engine (see, for example, Patent Document 1). A cooling water passage for circulating the cooling water in the cylinder head is provided around the ceiling of the combustion chamber, so that the combustion chamber can be quickly cooled. In addition to the above-described combustion chamber ceiling and cooling water passage, the cylinder head includes a communication portion for communicating the cooling water passage to the lower surface side, a plug hole for attaching a spark plug, an intake port, an exhaust port, a blow-by Components such as gas passages and, in some cases, exhaust manifolds, are also integrally formed.

  By the way, a cylinder head is usually manufactured by subjecting a molded product formed by low-pressure casting to grinding or polishing in order to accurately form the above-described components.

  The shape of the cylinder head varies in thickness depending on the arrangement of the components. In the low-pressure casting process, if there is a portion that is thinly formed near the path for supplying the molten metal, which is a liquid metal, the molten metal may not flow smoothly into the mold. For this reason, more cast holes are generated in the thin portion of the molded product. As a result, the cast hole is exposed to the surface in the process of shaving and polishing the molded product, and there may be a case where the cylinder head cannot be manufactured from the molded product, resulting in a decrease in manufacturing efficiency. . Further, since the thinly formed portion has a lower rigidity than other portions, there is a disadvantage that the processing accuracy by the process of performing the cutting process or the polishing is not sufficiently increased.

JP-A-60-237144

  The present invention focuses on the above-described problems, and an object of the present invention is to provide a cylinder head structure capable of effectively improving manufacturing efficiency and processing accuracy.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the structure of the cylinder head according to the present invention is a cylinder head body that constitutes a ceiling portion of a combustion chamber of a plurality of cylinders, and is a thin portion that is relatively thin from the ceiling portion to one side surface portion. The structure of the cylinder head has a relatively thick wall portion from the side portion to the other side surface portion, the cooling water passage surrounding the plurality of ceiling portions, and the cooling water passage formed in the thin portion A thin-side communicating portion that opens to communicate with the lower surface side of the cylinder head body, and a thick-side communication portion that is formed in the thick portion and opens to communicate the cooling water passage to the lower surface side of the cylinder head body. And the opening area of the thin-side communication part is smaller than the opening area of the thick-side communication part.

  If this is the case, by making the opening area of the thin side communication part smaller than that of the thick side communication part, a space for the molten metal to flow during low-pressure casting in the cylinder head manufacturing process is secured, and the occurrence of cast holes is suppressed. can do. As a result, it is possible to provide a cylinder head having a structure capable of effectively improving manufacturing efficiency and processing accuracy.

  In the cylinder head body, the front side and the back side end side by side along the direction in which the plurality of ceiling portions are arranged, and the region between the ceiling portion of the combustion chamber closest to the end portion, respectively. In order to make the flow of the molten metal smoother when the cooling water passage is provided with a front-side communication portion and a rear-side communication portion that open to communicate with the lower surface side of the cylinder head body, The opening area of one of the side communication part and the back side communication part is larger than the other opening area, and the ceiling of the combustion chamber closest to one of the front side communication part and the back side communication part It is desirable that the opening area of the former is smaller than the opening area of the latter with respect to the thin side communication part and the thick side communication part located on both sides of the part.

  In particular, in the case where the cylinder head body includes a lubricating oil passage formed in a thin portion close to an end where one of the front side communication portion and the back side communication portion is located, the manufacturing efficiency In addition, in order to improve the cooling efficiency by further improving the processing accuracy and the flow of the cooling water to be smooth, there is a gap between the lubricating oil passage and the ceiling portion of the combustion chamber closest to the lubricating oil passage. It is preferable that the thin communication portion is not formed.

  According to the present invention, it is possible to provide a cylinder head capable of effectively improving manufacturing efficiency and processing accuracy.

The typical figure which looked at the structure concerning one embodiment of the present invention from the back side. The bottom view of the cylinder head concerning the embodiment. The figure which shows the opening exposed through a gasket in FIG. The figure which showed the AA line end surface which concerns on FIG. 3 upside down. The figure which showed the BB line end surface concerning FIG. 3 upside down.

  An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the outline | summary of the internal combustion engine for vehicles which is a structure in this embodiment is shown. The internal combustion engine of the present embodiment is, for example, a port injection type four-stroke spark ignition engine, and includes three cylinders 1a, 1b, and 1c. The cylinders 1a, 1b and 1c are arranged in series in order from the front side which is the front side to the rear side which is the back side. This internal combustion engine is firmly fixed in a state where the cylinder block 2, the gasket 3 and the cylinder head 4 are layered in this order from the lower side so as to constitute the cylinders 1 a, 1 b and 1 c inside. The internal combustion engine forms a water jacket 5 that is a flow path across the cylinder block 2, the gasket 3, and the cylinder head 4 in order to avoid an excessive temperature rise due to combustion of the cylinders 1 a, 1 b, 1 c. In the present embodiment, the gasket 3 is formed by, for example, stacking a plurality of gasket members having substantially the same outer shape. As shown in FIGS. 4 and 5, the gasket 3 has at least a pair of openings 30 for allowing cooling water to pass therethrough at the front end. Further, in the gasket 3, a different opening for supplying cooling water to the cylinder head side is provided at a place other than the opening 30, but description of such a configuration is omitted. 4 and 5, the AA line end surface and the BB line end surface according to FIG. 3 are shown upside down for convenience of explanation, and the vertical direction of the internal combustion engine and the vertical direction in the drawings are made to coincide.

  As schematically shown in FIG. 1, the water jacket 5 introduces cooling water pumped from the outside by a water pump (not shown) from the pressure inlet 5a, and circulates the cooling water thoroughly in the internal combustion engine. The water jacket 5 is provided in a block-side flow path 51 for circulating cooling water in a plane in the cylinder block 2 and in the cylinder head 4 at a position overlapping the block-side flow path 51 in plan view. A communication flow path 52 that connects the head side flow path 53 that is a cooling water passage for circulating the cooling water in the head 4, and the downstream end of the block side flow path 51 and the upstream end of the head side flow path 53. And have. In addition, in the same figure, illustration and detailed description are abbreviate | omitted about the discharge port which discharges cooling water, and the detailed flow path branched from each flow path.

  The block-side flow path 51 turns back the cooling water, which is press-fitted from the pressure inlet 5a by a water pump (not shown) provided on the exhaust side between the first cylinder 1a and the second cylinder 1b, from the exhaust side to the third cylinder 1c. The cylinder block 2 is cooled by circulating through the intake side to the vicinity of the first cylinder 1a again.

  The communication flow path 52 communicates to raise most of the cooling water from the block side flow path 51 in a substantially vertical direction and supply it to the head side flow path 53.

  The head side flow path 53 is continuous with the communication flow path 52 and extends substantially along the intake side flow path 54 from the first cylinder 1 a to the third cylinder 1 c in the cylinder head 4. In this way, it has an exhaust side flow passage 55 extending from the first cylinder 1a to the exhaust side of the third cylinder 1c.

  FIG. 2 shows the bottom surface of the cylinder head body constituting the cylinder head 4. The cylinder head 4 is formed by integrally molding a molded product by low-pressure casting, and thereafter, the molded product is appropriately cut and polished. FIG. 3 shows the opening portion of the cylinder head 4 that is blocked by the gasket 3 (not shown) by a broken line.

  The cylinder head 4 has the head-side flow path 53 that is a cooling water passage inside the cylinder head main body, and from the front side that is the front side to the rear side that is the back side while being surrounded by the head-side flow path 53. The ceiling portion 41 of the three combustion chambers arranged side by side and the head side flow path 53 are opened to communicate with the lower surface side, that is, the gasket 3 and the cylinder block 2 side, and from the ceiling portion 41 to both side surfaces. And communication portions 42 provided at the respective locations. In the cylinder head 4 according to this embodiment, the main gallery 43 that is a lubricating oil passage positioned on the intake side near the first cylinder 1a and the exhaust manifold 44 are integrally formed on the exhaust side. That is, by forming the exhaust manifold 44 integrally, the cylinder head 4 has a thick portion 4b that is relatively thicker from the ceiling portion 41 to the exhaust side, that is, the side surface portion on the other side. The thin portion 4a that is relatively thinner than the thick portion 4b is formed up to the side portion on the one-side intake side.

  Thus, in the cylinder head 4 according to the present embodiment, the communication part 42 is formed in the thin part 4a, and the thin side communication part is opened to communicate the head side flow path 53 to the lower surface side of the cylinder head body. An intake side communication portion 42a, and an exhaust side communication portion 42b which is formed in the thick portion 4b and which opens to connect the head side flow path 53 to the lower surface side of the cylinder head body. And the opening area of the intake side communication portion 42a is smaller than the opening area of the exhaust side communication portion 42b.

  Hereinafter, the configuration of each part of the cylinder head 4 will be described.

  The ceiling 41 constitutes the upper part of the first cylinder 1a, the second cylinder 1b, and the third cylinder 1c, a plug hole 45 for attaching a plug (not shown) at the center, two intake ports 46 on the intake side, and exhaust Two exhaust ports 47 are drilled on the side, to which an unillustrated intake valve and exhaust valve are attached, and a squish 48 for promoting the flow of the air-fuel mixture is formed at the periphery. The opening area where the intake port 46 is formed is set larger than the opening area where the exhaust port 47 is formed. The main gallery 43 is for raising the lubricating oil from the cylinder block 2 side slightly on the front side and on the intake side of the first cylinder 1a. Specifically, a head bolt (not shown) is attached to the main gallery 43, and the clearance formed between the head bolt and the main gallery 43 is used to lubricate the lubricating oil by the heat of the ceiling portion 41 from the cylinder block 2 side. To pass through to heat.

  The communication part 42 has an intake side communication part 42 a connected to the intake side flow path 54 and an exhaust side communication part 42 b connected to the exhaust side flow path 55 connected to the exhaust side flow path 55. The intake-side communication portion 42a includes a large intake-side communication portion 42a1 that is a front-side communication portion having the largest opening area between the ceiling portion 41 constituting the first cylinder 1a and the front-side end portion, and each ceiling portion 41. And an intake side small communication portion 42a2 having an opening area smaller than that of the intake side large communication portion 42a1, and a rear intake side communication portion 42a3 which is a rear side communication portion formed on the rearmost side. The exhaust side communication portion 42b is disposed in the vicinity of the exhaust side large communication portion 42b1 having the largest opening area between the ceiling portion 41 constituting the first cylinder 1a and the front side end portion, and the exhaust portions 42b1. It has an exhaust side small communication part 42b2 having an opening area smaller than that of the side large communication part 42b1, and a rear exhaust side communication part 42b3 which is a rear side communication part formed on the rearmost side.

  Here, in the cylinder head 4 according to the present embodiment, in the manufacturing process by low pressure casting, the molten metal, which is a liquid metal, is introduced into the mold from the molten metal supply regions X provided at four locations on the bottom side. Casted. Specifically, the molten metal supply region X includes a first intake side region X1 positioned on the intake side of the first cylinder 1a, a second intake side region X2 positioned on the intake side of the second cylinder 1b, and a first It has a first exhaust side region X3 positioned on the exhaust side of the cylinder 1a and a second exhaust side region X4 positioned on the exhaust side of the second cylinder 1b. Particularly in the first intake side region X1, in the thin portion 4a, the intake port 46 and the squish 48 constituting the ceiling portion 41 of the first cylinder 1a, the intake side large communication portion 42a1 and the openings constituting the main gallery 43 are concentrated. It corresponds to the place.

  Therefore, in the present embodiment, by positioning the non-communication region 4X in which the intake side communication portion 42a is not formed at a location between the main gallery 43 and the first cylinder 1a closest to the main gallery 43, the first intake side By facilitating the smooth flow of the molten metal in the region X1, the occurrence of a void in the cavity of the molded product in the vicinity of the first intake side region X1 is effectively suppressed. Further, by forming the communication portions 42 other than the portion where the non-communication region 4X is provided, the intake side communication portion 42a and the exhaust side communication portion 42b are formed in a substantially contrasting manner, thereby reducing the opening area of the intake side communication portion 42a. The opening area of the exhaust side communication part 42b located in the vicinity of the end is made smaller. In particular, the opening area of the intake side communication portion 42a provided around the ceiling portion 41 forming the first cylinder 1a located in the vicinity of the intake side large communication portion 42a1 and the exhaust side large communication portion 42b1 which is the front side communication portion. It is made smaller than the opening area of the exhaust side communication part 42b.

  Here, in the present embodiment, the difference in the mode in which the cooling water flows in the vicinity of the intake side large communication portion 42a1 and the exhaust side large communication portion 42b1 by providing the non-communication region 4X on the intake side is compared with FIG. 4 and FIG. I will explain. In the figure, the flow of cooling water is indicated by thick arrows. In FIG. 4, the cooling water flowing through the opening from the communication channel 52 flows smoothly along the bottom surface side of the intake side channel. On the other hand, in FIG. 5, the cooling water flowing through the opening 30 from the communication flow path 52 temporarily stays at the location of the exhaust side small communication portion 42 b 2 whose bottom surface is blocked by the gasket 3. That is, on the intake side, cooling water in the vicinity of the first cylinder 1a provided with the non-communication region 4X is quickly passed to contribute to cooling of the ceiling portion 41 constituting the second cylinder 1b and the third cylinder 1c. Further, the retention of the cooling water as shown in FIG. 5 is similarly performed at the locations where the intake side small communication portions 42a2 and the exhaust side small communication portions 42b2 provided by the gasket 3 as shown in FIG. It goes without saying that it happens. As shown in FIGS. 2 and 3, a main gallery 43 through which lubricating oil flows is provided in the vicinity of the non-communication region 4X, but excessive cooling by the accumulated cooling water is avoided. As a result, the lubricating oil heated by the ceiling portion 41 and having a reduced viscosity can be supplied to the cylinder block 2 side.

  With the configuration as described above, the cylinder head 4 according to the present embodiment can reduce the opening area of the intake side communication portion 42a, which is the thin side communication portion, to be smaller than the opening area of the exhaust side communication portion 42b. The space through which the molten metal flows during low-pressure casting in the manufacturing process 4 is effectively ensured, and the occurrence of a cast hole can be suppressed. With such a structure, the yield when processing from a molded product to a finished cylinder head 4 is also effectively secured. That is, the cylinder head 4 according to the present embodiment realizes a structure that can effectively improve manufacturing efficiency and processing accuracy.

  Further, a rear intake side communication portion 42a3 formed on the rear side on the third cylinder 1c side to introduce cooling water between the front side end portion on the front side and the ceiling portion 41 located in the vicinity of the end portion. And in order to make the flow of the molten metal more smooth at the time of manufacturing at the place where the intake side large communication portion 42a1 and the exhaust side large communication portion 42b1 formed larger than the rear exhaust side communication portion 42b3 are formed, the front side The opening area of the intake side communication portion 42a provided around the ceiling portion 41 constituting the first cylinder 1a is made smaller than the opening area of the corresponding exhaust side communication portion 42b. In addition, by applying such a configuration, the diameter of the molded product after low-pressure casting, such as machining the valve seat at the end of the intake port 46, is thinner and the rigidity is reduced due to the larger diameter than the exhaust port 47. Therefore, it is possible to effectively reduce the possibility of processing defects before the cylinder head 4 is finished from the molded product.

  In particular, in the present embodiment, a non-communication region 4X in which the intake side communication portion 42a is not provided is set between the main gallery 43 serving as a lubricating oil passage and the ceiling portion 41 constituting the first cylinder 1a closest to the main gallery 43. By doing so, the cooling water is rapidly supplied to the rear side, that is, the second cylinder 1b and the third cylinder 1c side, which contributes to the improvement of the cooling efficiency of the second cylinder 1b and the third cylinder 1c. Further, by such a configuration, it is possible to effectively prevent the lubricating oil passing through the main gallery 43 from being unnecessarily cooled by the cooling water, so that heat from the ceiling portion 41 is easily transmitted to the lubricating oil. As a result, the temperature of the lubricating oil can be raised quickly, and the mechanical loss of the internal combustion engine that occurs when the viscosity of the lubricating oil is high is reduced, thereby contributing to further lower fuel consumption.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the aspect in which the opening area of the communication portion is increased or the lubricating oil passage is formed in the vicinity of the end portion on the front side has been disclosed. Or a lubricating oil passage may be provided. Further, the specific form such as the detailed shape of the cooling water passage and the specific arrangement of the flow path for supplying the cooling water from the cylinder block to the cylinder head is not limited to that of the above embodiment, but the existing one is used. Various embodiments including the above can be applied.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used as a structure of a cylinder head constituting an internal combustion engine.

4 ... Cylinder head 41 ... Ceiling part (ceiling part) of combustion chamber
42 ... communication part 42a ... thin side communication part (intake side communication part)
42b ... Thickness side communication part (exhaust side communication part)
43 ... Lubricating oil passage (main gallery)
53. Cooling water passage (head side passage)

Claims (3)

In the cylinder head body constituting the ceiling part of the combustion chamber of a plurality of cylinders, the thin part from the ceiling part to the side part on one side is relatively thin, and the part from the ceiling part to the side part on the other side is relatively The structure of the cylinder head is a thick part,
A cooling water passage surrounding the plurality of ceiling portions;
A thin-side communicating portion that is formed in the thin-walled portion and opens to communicate the cooling water passage to the lower surface side of the cylinder head body;
A thick-side communicating portion that is formed in the thick-walled portion and opens to allow the cooling water passage to communicate with the lower surface side of the cylinder head body;
A structure of a cylinder head, wherein an opening area of the thin side communication portion is smaller than an opening area of the thick side communication portion. In the cylinder head body, the front side and the back side end side by side along the direction in which the plurality of ceiling portions are arranged, and the region between the ceiling portion of the combustion chamber closest to the end portion, respectively. Comprising a front side communication portion and a back side communication portion that open to communicate the cooling water passage to the lower surface side of the cylinder head body;
The opening area of one of the front side communication part and the back side communication part is larger than the other opening area,
For the thin side communication portion and the thick side communication portion located on both sides of the ceiling portion of the combustion chamber closest to one of the front side communication portion and the back side communication portion, the former opening area is set to the latter. The cylinder head structure according to claim 1, wherein the structure is smaller than the opening area. In the cylinder head body, comprising a lubricating oil passage formed in a thin portion near one end where one of the front side communication portion and the back side communication portion is located,
The cylinder head structure according to claim 1 or 2, wherein the thin-side communication portion is not formed between the lubricating oil passage and a ceiling portion of the combustion chamber closest to the lubricating oil passage.

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