JP2008063946A - Cylinder head and method of manufacturing the cylinder head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder head and a method of manufacturing the cylinder head capable of securing sufficient fitting strength while preventing a galling phenomenon and also eliminating a gap between a valve seat and a seat fitting hole on a combustion chamber side so as to secure a sufficient contact length. <P>SOLUTION: A ceiling surface 40b that forms a combustion chamber 40 of a head main body 10 is formed by removing a projection 37 having a chamfered part 37a for guiding the valve seat 34 to fit the same into the seat fitting hole 35. Since the projection 37 is removed after fitting the valve seat 34 into the seat fitting hole 35, a guide diameter and a guide length of the projection can be set at large values arbitrarily so that the sufficient fitting strength can be secured while preventing the galling phenomenon effectively. Further, the gap between the valve seat 34 and the seat fitting hole 35 on the side of the combustion chamber 40 can be eliminated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylinder head for an internal combustion engine, and more particularly to a shape of a combustion chamber side of a port opened and closed by a valve.

  An intake port and an exhaust port (hereinafter simply referred to as a port) are formed in the cylinder head mounted on the cylinder block, and the port communicates with a combustion chamber formed by the cylinder block and the cylinder head. It has become. A seat mounting hole is formed in the opening on the combustion chamber side of the port. In this seat mounting hole, a valve seat on which an intake valve and an exhaust valve (hereinafter simply referred to as a valve) for opening and closing the port are separated and seated. It is press-fitted.

  The diameter dimension of the seat mounting hole is set to be smaller than the diameter dimension of the valve seat (for example, a dimensional difference of 50 micrometers). Using a device or the like, a predetermined load (for example, 2 tons) is applied to the valve seat toward the seat mounting hole and press-fitted and mounted.

  By the way, the molding accuracy of the seat mounting hole (shaft core position accuracy, etc.) formed in the port of the cylinder head varies within a predetermined processing tolerance, so press fitting of the valve seat into the seat mounting hole by an assembling device or the like. In some cases, the shaft core of the valve seat and the shaft core of the seat mounting hole may be misaligned, and the valve seat may bite the seat mounting hole. When such a so-called galling phenomenon occurs, there arises a problem that the press fitting failure of the valve seat, that is, the fitting strength (disengagement strength) of the valve seat varies.

  Therefore, for example, Patent Literature 1 and Patent Literature 2 describe a chamfered portion formed on the valve seat mounting direction side in order to suppress the occurrence of such a galling phenomenon. The techniques described in Patent Document 1 and Patent Document 2 can make the valve seat easy to press-fit by correcting the misalignment between the valve seat and the seat mounting hole by using the chamfered portion as a guide. It is.

  Here, the permissible amount of misalignment is determined by the guide diameter, that is, the difference in diameter between the opposite end surfaces of the valve seat and the seat mounting hole. If this guide diameter is large, the allowable misalignment is allowed. Capacity also increases. On the other hand, the ease of press-fitting of the valve seat is determined by the guide length dimension of the chamfered portion that gives the inlet angle, that is, the length dimension of the chamfered portion in the mounting direction of the valve seat. The longer it is, the easier it is to press-fit by reducing the press-fit resistance. That is, by securing both the guide diameter dimension and the guide length dimension as much as possible, the galling phenomenon can be effectively suppressed.

  The technique described in Patent Document 1 forms a chamfered portion on the outer periphery on the valve seat mounting direction side and a notch on the inner periphery, thereby ensuring a predetermined guide diameter dimension and guide length dimension. At the same time, the rigidity in the mounting direction side of the valve seat is decreased, and the press-fitting load into the seat mounting hole of the valve seat is reduced to suppress the galling phenomenon.

In addition, the technique described in Patent Document 2 is to improve the valve seat press-fitting device to suppress misalignment between the valve seat and the valve seat fitting hole (seat mounting hole). The outer periphery on the mounting direction side of the valve seat to be mounted has a chamfered portion similar to that of Patent Document 1, and also has a chamfered portion on the outer periphery on the opening side of the valve seat fitting hole. Thus, the mutual chamfered portions function as guides so that a relatively large guide diameter can be secured.
JP 2006-029151 A (FIG. 1) JP 2004-116414 A (FIG. 1)

  However, according to the technique described in Patent Document 1, since the rigidity in the mounting direction side of the valve seat is reduced, the pull-out strength of the valve seat is small, for example, the coefficient of thermal expansion between the valve seat and the cylinder head Due to the difference, the valve seat is loosened with respect to the seat mounting hole, and as a result, problems such as rattling of the valve seat may occur. Even if the notch in the inner periphery on the valve seat mounting direction side is omitted in the technique described in Patent Document 1 in order to increase the pull-out strength, the chamfered portion that functions as a guide has an outer periphery on the valve seat mounting direction side. Therefore, a sufficient guide diameter dimension and guide length dimension cannot be secured, and the galling phenomenon cannot be sufficiently suppressed.

  Further, according to the technique described in Patent Document 2 (see the explanatory diagrams of FIGS. 6 and 7 of the present specification), the chamfered portion b is formed on the opening side of the seat mounting hole a, so that the valve seat A relatively large guide diameter dimension and guide length dimension can be obtained in cooperation with the chamfered portion d on the mounting direction side of c, and therefore a sufficient suppression of the galling phenomenon can be expected. However, after the valve seat c is moved by the press-fitting device as indicated by the arrow in the drawing and the valve seat c is mounted in the seat mounting hole a, the valve seat c is annularly formed between the seat mounting hole a and the combustion chamber e side. Therefore, the length dimension (contact length) g of the contact portion of the valve seat c with the seat mounting hole a is shortened. If the contact length g is short, the thermal conductivity from the valve seat c to the seat mounting hole a deteriorates, the heat dissipation of the valve seat c decreases, and the seat surface of the valve seat c that requires airtightness is early. Problems such as wear may occur. Further, not only the unburned air-fuel mixture remains in the gap f, which causes a decrease in engine output, but also scraps (burrs) generated when the valve seat c is mounted in the seat mounting hole a remain in the gap f. A problem that the burr enters the piston gap during operation of the engine may damage the piston sliding surface of a cylinder liner (not shown).

  An object of the present invention is to provide a cylinder head capable of ensuring a sufficient pulling strength while suppressing a galling phenomenon, and a sufficient contact length by eliminating a gap between the valve seat and the combustion chamber side of the seat mounting hole. It is another object of the present invention to provide a cylinder head manufacturing method.

  A cylinder head according to the present invention is a cylinder head for an internal combustion engine having a ceiling surface that is mounted on a cylinder block and forms a combustion chamber together with the cylinder block, and a port communicating with the combustion chamber is formed. A head body having a seat mounting hole formed in the opening on the combustion chamber side, and a valve seat press-fitted into the seat mounting hole and seated on and off from the seat, and a tapered hole connected to the seat mounting hole. Forming the ceiling surface by removing the guide protrusion after the valve seat is press-fitted into the seat mounting hole through the guide protrusion formed in the head body and protruding into the combustion chamber. It is characterized by.

  The cylinder head according to the present invention is characterized in that the ceiling surface is formed by removing the end surface of the valve seat on the combustion chamber side together with the removal of the guide protrusion.

  The cylinder head manufacturing method of the present invention manufactures a cylinder head for an internal combustion engine that has a ceiling surface that is mounted on a cylinder block and forms a combustion chamber together with the cylinder block, and has a port that communicates with the combustion chamber. A method for manufacturing a cylinder head, comprising: a casting step of forming a head body including the port and a guide protrusion that forms an opening on the combustion chamber side of the port; and a sheet in the opening on the combustion chamber side of the port A cutting step of forming a mounting hole and forming a tapered hole connected to the seat mounting hole in the guide projecting portion, and a sheet that is guided by the tapered hole and press-fitted into the seat mounting hole a valve seat on which a valve is seated. The method includes a press-fitting step and a ceiling surface forming step of forming the ceiling surface by removing the guide protrusion.

  The cylinder head manufacturing method of the present invention is characterized in that, in the ceiling surface forming step, the ceiling surface is formed by removing the end surface of the valve seat on the combustion chamber side together with the removal of the guide protrusion. To do.

  In the cylinder head manufacturing method of the present invention, in the ceiling surface forming step, the seat surface of the valve seat and the support surface of the valve guide that supports the valve are formed in addition to the formation of the ceiling surface. It is characterized by.

  According to the present invention, the ceiling surface formed on the combustion chamber side of the head main body is formed by removing the guide protrusion formed with the tapered hole for guiding the valve seat to the seat mounting hole. Therefore, the mounting operation of the valve seat to the seat mounting hole can be smoothly performed by the guide function of the tapered hole in the guide protrusion. Since the guide protrusion is removed after the valve seat is installed in the seat mounting hole, the guide diameter dimension and the guide length dimension can be set to be arbitrarily large. Strength can be secured. Further, since the guide protrusion having the tapered hole formed after the valve seat is mounted in the seat mounting hole is removed, a gap between the valve seat and the combustion chamber side of the seat mounting hole due to the tapered hole can be eliminated. Therefore, it is possible to suppress the burrs and unburned mixture from remaining in the combustion chamber, and to ensure a sufficient contact length.

  According to the present invention, since the ceiling surface is formed by removing the end surface of the valve seat on the combustion chamber side together with the removal of the guide protrusion, the ceiling surface can be formed into a smooth shape without irregularities.

  According to the present invention, a casting process for forming a head body having a guide protrusion for guiding the mounting of a valve seat, a cutting process for forming a seat mounting hole and a tapered hole connected thereto, and guiding the valve seat to the tapered hole. Through the sheet press-fitting process for press-fitting into the seat mounting hole and the ceiling surface forming process for forming the ceiling surface of the combustion chamber by removing the guide protrusions, and sufficient removal while suppressing the galling phenomenon effectively. A cylinder head with sufficient strength can be manufactured. Further, it is possible to manufacture a cylinder head in which there is no gap between the valve seat and the seat mounting hole and the mutual contact length is sufficiently secured.

  According to the present invention, the ceiling surface forming step forms the ceiling surface by removing the guide protrusion and removing the end surface of the valve seat on the combustion chamber side. can do.

  According to the present invention, the ceiling surface forming step performs the formation of the seat surface of the valve seat and the support surface of the valve guide that supports the valve in addition to the formation of the ceiling surface. Finishing work can be performed to ensure the sliding performance and airtight performance of the valve.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a cross-sectional view showing a finished cylinder head according to the present invention, FIG. 2 is a cross-sectional view showing the cylinder head in the material state of FIG. 1, and FIGS. 3 (a) to 3 (d) are views of the cylinder head of FIG. FIG. 4 is an explanatory diagram illustrating an example of mounting a valve seat in a seat mounting hole, and FIG. 5 is a partially enlarged sectional view of a broken line circle B portion of FIG. ing.

  As shown in FIG. 1, a head body (cylinder head) 10 is disposed and fixed on a cylinder block 11 in which a piston (not shown) reciprocates in a vertical direction via a cylinder liner (not shown). The head body 10 is made of, for example, a metal material such as an aluminum material. The head main body 10 and the cylinder block 11 are airtightly attached to each other via a gasket (not shown), and the combustion chamber 40 is formed by the head main body 10 and the cylinder block 11.

  The head body 10 has an intake port 20 having a substantially L-shaped section through which an air-fuel mixture generated by mixing fuel and air at a predetermined ratio flows, and a substantially L-shaped section through which exhaust gas flows. An exhaust port 30 is formed. The intake port 20 and the exhaust port 30 communicate with the combustion chamber 40, respectively, and the ceiling surfaces 40a and 40b forming the combustion chamber 40 are formed on the combustion chamber 40 side of the intake port 20 and the combustion chamber 40 side of the exhaust port 30. Is provided. 1 and 2 are water jackets through which cooling water sent from a water pump (not shown) flows.

  On the upper side of the intake port 20 and the exhaust port 30 in the figure, there are provided guide holes 21 and 31 that are formed at a predetermined angle (for example, 45 °) with respect to each other. -Shaped valve guides 22 and 32 are mounted. The valve guides 22 and 32 are adapted to slidably guide the valve stems 23a and 33a of the intake valve 23 and the exhaust valve 33 indicated by a two-dot chain line in the drawing without substantial resistance.

  Cylindrical seat mounting holes 25 and 35 into which annular valve seats 24 and 34 are press-fitted are formed on the combustion chamber 40 side of the intake port 20 and the exhaust port 30, and the diameter dimensions of the seat mounting holes 25 and 35 are formed. Is smaller than the diameter of the valve seats 24, 34, for example, so as to have a dimensional difference of about 50 micrometers. Thus, the valve seats 24 and 34 are pressed into the seat mounting holes 25 and 35 with a load of about 2 tons, for example, so that the valve seats 24 and 34 have a sufficient pull-out strength. Thus, the sheet mounting holes 25 and 35 are firmly fixed. Accordingly, the valve seats 24 and 34 fall out of the seat mounting holes 25 and 35 due to the difference in thermal expansion coefficient even under a state where a large temperature difference occurs from when the engine is cold to when the engine is warmed up. There is nothing.

  On the radially inner peripheral side of the valve seats 24, 34, annular seat surfaces 24a, 34a that are inclined at a predetermined angle are formed, and the intake valve 23 and the exhaust valve 33 are formed on these seat surfaces 24a, 34a. The annular contact surfaces 23c and 33c in the valve portions 23b and 33b are separated and seated. The contact surfaces 23c and 33c are separated from and seated on the seat surfaces 24a and 34a, so that airtightness when the valves 23 and 33 are closed is ensured.

  On the upper side of the sheet surfaces 24a and 34a in the figure, annular inclined surfaces 24b and 34b are provided continuously to the sheet surfaces 24a and 34a, and these inclined surfaces 24b and 34b are formed on the sheet surfaces 24a and 34a. It is gentler than the tilt angle. The inclined surfaces 24b and 34b play a role of allowing inflow of air-fuel mixture from the intake port 20 to the combustion chamber 40 and outflow of exhaust gas from the combustion chamber 40 to the exhaust port 30 without substantial resistance.

  On the combustion chamber 40 side of the seat mounting holes 25 and 35, annular ceiling surfaces 40a and 40b forming the combustion chamber 40 are formed, and the ceiling surfaces 40a and 40b are illustrated so that the surfaces thereof are smoothed. It is formed by cutting or polishing with a processing machine that does not. The ceiling surfaces 40a and 40b are formed by the contact surfaces 23c and 33c of the valves 23 and 33 contacting (closing) the seat surfaces 24a and 34a, respectively, between the ports 20 and 30 and the combustion chamber 40 side. It is arranged on the boundary line between.

  The valve guides 22 and 32 mounted in the guide holes 21 and 31 are set to have an axial dimension longer than the axial dimension of the guide holes 21 and 31, and the valve guides 22 and 32 are valve valves in the entire axial direction. The stems 23a and 33a are guided. The support surfaces 22a and 32a formed on the inner peripheral side of the guide holes 21 and 31 are cut by a processing machine or the like (not shown) so that the valve stems 23a and 33a have a predetermined surface roughness so that the valve stems 23a and 33a can slide smoothly. Processing and polishing are applied.

  FIG. 2 shows a material state (pre-processing state) before mounting components such as a valve seat constituting the head body 10. Here, the material state of the head main body 10 is, for example, a state in which a molten aluminum material is formed by casting such as low pressure casting, and the sheet mounting holes 25 and 35 are not subjected to any cutting processing. Say no state.

  As shown in FIG. 2, the openings 26 and 36 (the seat mounting holes 25 and 35 are formed later) of the intake port 20 and the exhaust port 30 of the head main body 10 on the combustion chamber 40 side are shown by two-dot chain lines in the figure. The annular projecting portions 27 and 37 as guide projecting portions are formed so as to project a predetermined amount from the ceiling surfaces 40a and 40b shown in FIG.

  The protrusions 27 and 37 have a substantially semicircular cross section, and a sheet mounting hole formed by cutting the openings 26 and 36 into a predetermined shape on the inner peripheral side of the protrusions 27 and 37. A chamfered portion as a tapered hole is formed to guide the mounting of the valve seats 24 and 34 (see FIG. 1) to the 25 and 35. Further, as shown in FIG. 1, the protrusions 27 and 37 are removed by cutting after the valve seats 24 and 34 are mounted in the seat mounting holes 25 and 35.

  Next, the manufacturing method of the cylinder head in the present invention configured as described above will be described in detail with reference to the drawings. Since the intake port 20 and the exhaust port 30 have the same configuration, only the exhaust port 30 will be described after the description based on FIG. 3, and the description on the intake port 20 side will be omitted.

  First, the molten aluminum material is poured into a mold having a predetermined shape having a suction port 20, an exhaust port 30, guide holes 21 and 31, and cores serving as water jackets S <b> 1 to S <b> 3 (see FIG. 2) shown in FIG. 2. At low pressure casting. 2 is formed, that is, the head body 10 having the combustion chamber 40 and the protrusions 27 and 37 is formed (casting process).

  Next, as shown in FIG. 3A, the opening 36 of the exhaust port 30 in the head main body 10 is centered using a cutting tool such as a boring tool so as to be in the shape of a two-dot chain line in the figure. Apply boring. As a result, as shown in FIG. 3B, a seat mounting hole 35 in which the valve seat 34 is mounted and a chamfered portion 37a connected to the seat mounting hole 35 are formed (cutting process). Here, the diameter dimension of the chamfered portion 37a on the combustion chamber 40 side is set to be larger than the diameter dimension of the valve seat 34, and has a sufficient guide diameter dimension as compared with the conventional technique. Further, the guide length dimension of the chamfered portion 37a is sufficiently longer than that of the conventional technique because the chamfered portion 37a is formed on the protruding portion 37.

  After that, as shown in FIG. 4, a valve guide 32 is mounted on the guide hole 31 of the head body 10 after the cutting process, and the head is placed on a jig provided in a valve seat press-fitting device (not shown). The main body 10 is set. Then, the valve seat 34 is set on the press-fitting head P of the valve seat press-fitting device, and the drive mechanism (not shown) of the valve seat press-fitting device is driven so that the valve seat 34 faces the arrow direction in FIG.

  The valve seat 34 is continuously moved by the press-fitting head P. As a result, first, the seat mounting hole 35 side of the valve seat 34 comes into contact with the chamfered portion 37 a formed in the protruding portion 37. As the valve seat 34 continues to move, the shaft center of the valve seat 34 gradually coincides with the shaft center of the seat mounting hole 35 by the automatic centering function (guide function) of the chamfered portion 37a. To go. Thereafter, the valve seat 34 is mounted at a predetermined position with respect to the seat mounting hole 35 as shown in FIG. (Sheet press-fitting process). At this time, by the automatic centripetal function of the chamfered portion 37a and a sufficient guide length, the galling phenomenon with respect to the seat mounting hole 35 by the valve seat 34 is suppressed, and the occurrence of burrs and the like is suppressed.

  Next, the head body 10 that has finished the sheet press-fitting process is taken out from the jig of the valve seat press-fitting device, and is cut using a cutting tool or the like (not shown) so as to have a shape indicated by a two-dot chain line in FIG. Apply. In this cutting process, both the entire projecting portion 37 (the chamfered portion 37a) and the end surface of the valve seat 34 on the combustion chamber 40 side are removed. As a result, as shown in FIG. 5, a gap (see reference numeral f in FIG. 7) as shown in the related art is not formed between the valve seat 34 and the seat mounting hole 35. Therefore, the contact length of the valve seat 34 with the seat mounting hole 35 is longer than that of the conventional technique.

  Thus, by performing the cutting process, there is no gap between the valve seat 34 and the seat mounting hole 35 as shown in FIG. 3D, and the smoothed ceiling surface 40b of the combustion chamber 40 is formed. It is formed (ceiling surface forming step).

  In the ceiling surface forming step, the seat surface 34a and the inclined surface 34b of the valve seat 34 and the support surface 32a (see FIG. 4) of the valve guide 32 are simultaneously formed by cutting or polishing simultaneously with the formation of the ceiling surface 40b. Try to form. Therefore, the axial surfaces of the ceiling surface 40b, the seat surface 34a, the inclined surface 34b, and the support surface 32a are finished in a state of being accurately aligned.

  After that, the exhaust valve 33 (see FIG. 1) is mounted on the valve guide 32 and other components (not shown) are mounted on the head body 10 that has finished the ceiling surface forming process, thereby completing the head body 10. To do.

  As described above in detail, according to the cylinder head of the present invention, the chamfered portion for guiding the mounting of the valve seat 34 to the seat mounting hole 35 on the ceiling surface 40 b formed on the combustion chamber 40 side of the head body 10. Since the projecting portion 37 formed with the 37a is removed, the mounting work of the valve seat 34 to the seat mounting hole 35 can be smoothly performed by the guide function of the chamfered portion 37a in the projecting portion 37. it can. At this time, since the protruding portion 37 is removed after the valve seat 34 is mounted in the seat mounting hole 35, the guide diameter dimension and the guide length dimension can be set arbitrarily large, and therefore the galling phenomenon is effectively suppressed. However, it is possible to ensure sufficient pulling strength.

  Further, since the protruding portion 37 formed with the chamfered portion 37a is removed after the valve seat 34 is mounted in the seat mounting hole 35, the valve seat 34 by the chamfered portion 37a and the combustion chamber 40 side of the seat mounting hole 35 are removed. The gap between them can be eliminated. Therefore, it is possible to suppress burrs and unburned mixture from remaining in the combustion chamber, and it is possible to suppress damage to the piston sliding surface of the cylinder liner and reduction in engine output.

  Furthermore, since the contact length between the valve seat 34 and the seat mounting hole 35 can be sufficiently secured, the heat conductivity from the valve seat 34 to the seat mounting hole 35 is improved, and the heat dissipation of the valve seat 34 is improved. be able to. Therefore, early wear or the like due to heat of the valve seat 34 can be suppressed, and airtightness can be maintained for a long time.

  Further, according to the cylinder head of the present embodiment, the ceiling surface 40b of the combustion chamber 40 is formed by removing the end surface on the combustion chamber 40 side of the valve seat 34 together with the removal of the protruding portion 37, so the ceiling surface 40b Can be made into a smooth shape without irregularities. Therefore, the volume of the combustion chamber 40 can be reduced and the compression ratio can be improved, so that the engine output can be improved. This is particularly effective for an internal combustion engine having a large compression ratio such as a diesel engine.

  Furthermore, according to the cylinder head manufacturing method of the present embodiment, the casting process for forming the head main body 10 including the protrusion 37 that guides the mounting of the valve seat 34, the seat mounting hole 35, and the chamfered portion connected thereto. A cutting process for forming 37a, a sheet press-fitting process for guiding the valve seat 34 to the chamfered part 37a and press-fitting into the seat mounting hole 35, and a ceiling for removing the protruding part 37 to form the ceiling surface 40b of the combustion chamber 40 By passing through the surface forming step, it is possible to manufacture a cylinder head that ensures a sufficient pulling strength while effectively suppressing the galling phenomenon. Further, it is possible to manufacture a cylinder head in which there is no gap between the valve seat 34 and the seat mounting hole 35 and the mutual contact length is sufficiently secured.

  Moreover, according to the cylinder head manufacturing method of the present embodiment, the ceiling surface forming step forms the ceiling surface 40b by removing the end surface on the combustion chamber 40 side of the valve seat 34 together with the removal of the protruding portion 37. Therefore, it is possible to form a smooth ceiling surface 40b without unevenness.

  Furthermore, according to the cylinder head manufacturing method of the present embodiment, the ceiling surface forming step includes the formation of the seat surface 34a of the valve seat 34 and the support of the valve guide 32 that supports the valve 33 in addition to the formation of the ceiling surface 40b. Since the surface 32a is formed, a finishing operation can be performed in order to ensure the sliding performance and airtight performance of the valve 33 during the ceiling surface forming process. Accordingly, the manufacturing process of the cylinder head can be simplified, and the respective shaft cores in the cylinder head components arranged on the shaft core of the valve 33 can be made to coincide with each other with high accuracy, thereby improving the reliability. .

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range which does not deviate from the summary. For example, in the above embodiment, the projection 37 and the end surface of the valve seat 34 on the combustion chamber 40 side are both removed. However, the present invention is not limited to this, and only the projection 37 is used. May be removed so as to be flush with the end face of the valve seat 34. Further, the removal amount of the protruding portion 37 may be adjusted so that a part of the protruding portion 37 remains.

  Furthermore, in the above-described embodiment, the same configuration is shown on the intake side and the exhaust side. However, the present invention is not limited to this, and the present invention is applied to only one side according to the engine characteristics or the like. You may apply.

  In the above embodiment, the formation of the seat surface 34a of the valve seat 34 and the formation of the support surface 32a of the valve guide 32 simultaneously with the formation of the ceiling surface 40b of the combustion chamber 40 has been described. However, the present invention is not limited to this, and the steps may be performed in different steps even if they are not the same step.

It is sectional drawing which shows the cylinder head of the finished product in this invention. It is sectional drawing which shows the cylinder head of the raw material state of FIG. (A)-(d) is a process explanatory drawing explaining the process sequence of the port of the cylinder head of FIG. It is explanatory drawing explaining the example of mounting | wearing to the seat mounting hole of a valve seat. It is a partial expanded sectional view of the broken-line circle | round | yen B part of FIG. It is sectional drawing explaining the structure of the seat mounting hole of the cylinder head in a prior art. It is a partial expanded sectional view of the broken-line circle | round | yen A part in FIG.

Explanation of symbols

10 Head body (cylinder head)
11 Cylinder block 20 Intake port (port)
23 Intake valve (valve)
24, 34 Valve seat 24a, 34a Seat surface 25, 35 Seat mounting hole 26, 36 Opening 27, 37 Projection (guide projection)
37a Chamfered part (tapered hole)
30 Exhaust port (port)
33 Exhaust valve (valve)
40 Combustion chamber 40a, 40b Ceiling surface

Claims (5)

A cylinder head for an internal combustion engine having a ceiling surface mounted on a cylinder block and forming a combustion chamber together with the cylinder block, wherein a port communicating with the combustion chamber is formed,
A head body having a seat mounting hole formed in an opening on the combustion chamber side of the port;
A valve seat that is press-fitted into the seat mounting hole and from which the valve is seated;
The guide protrusion is removed after the valve seat is press-fitted into the seat mounting hole through a guide protrusion provided in the head body that is formed in a tapered hole continuous with the seat mounting hole and protrudes into the combustion chamber. And forming the ceiling surface.   2. The cylinder head according to claim 1, wherein the ceiling surface is formed by removing the guide protrusion and removing an end surface of the valve seat on the combustion chamber side. A cylinder head manufacturing method for manufacturing a cylinder head for an internal combustion engine having a ceiling surface mounted on a cylinder block and forming a combustion chamber together with the cylinder block, wherein a port communicating with the combustion chamber is formed,
A casting step of forming a head body including the port and a guide protrusion that forms an opening on the combustion chamber side of the port;
A cutting step of forming a seat mounting hole in an opening on the combustion chamber side of the port, and forming a tapered hole connected to the seat mounting hole in the guide protrusion;
A seat press-fitting step of press-fitting a valve seat on which a valve is seated into and out of the seat mounting hole, guided by the tapered hole;
And a ceiling surface forming step of forming the ceiling surface by removing the guide protrusion.   4. The cylinder head manufacturing method according to claim 3, wherein in the ceiling surface forming step, the ceiling surface is formed by removing the end surface of the valve seat on the combustion chamber side together with the removal of the guide protrusion. A manufacturing method of a cylinder head, which is characterized.   5. The cylinder head manufacturing method according to claim 3, wherein the ceiling surface forming step includes formation of a seat surface of the valve seat and formation of a support surface of a valve guide that supports the valve in addition to the formation of the ceiling surface. And a method of manufacturing a cylinder head.

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