Manufacturing method for cylinder head

Abstract

A manufacturing method for a cylinder head is described. A masking member is attached to a cylinder head material, which followed by a film formation step. The masking member comprises a mask portion to mask the matching surface with the cylinder block, mask portions to mask each of the openings of intake and exhaust ports and a mask portion to mask at least one narrow region sandwiched between openings of two adjacent port holes and has the shortest distance between opening edges of the two adjacent port holes. All Mask portions are coplanar and linked directly to each other.

Claims

1. A manufacturing method for a cylinder head comprising the steps of: preparing a cylinder head material having a cylinder block matching surface with a cylinder block and an inner wall surface of an engine combustion chamber in a same plane, wherein at least three port holes corresponding to at least one intake port and at least one exhaust port are formed on the inner wall surface; attaching the cylinder head material to a masking member to mask a non-film formation region of the inner wall surface and the cylinder block matching surface; after the attachment of the masking member, injecting film material particles through the masking member onto the inner wall surface of the engine combustion chamber to form a heat shield film; and detaching the masking member from the cylinder head material after the formation of the heat shield film, wherein the masking member comprises: a matching surface mask portion that masks the matching surface with the cylinder block; port hole mask portions that are connected to the matching surface mask portion directly and mask openings of the at least three port holes; and a between openings mask portion that masks at least one narrow region which is sandwiched between openings of two adjacent port holes of the at least three port holes and has the shortest distance between opening edges of the two adjacent port holes of the at least three port holes, and is directly connected to both of the port hole mask portions that mask the openings of the adjacent port holes of the at least three port holes, and wherein the matching surface mask portion, the port hole mask portions and the between openings mask portion are coplanar.

2. The manufacturing method for a cylinder head according to claim 1, wherein the inner wall surface further includes a part hole that is a hole for housing an engine-related part, the between openings mask portion masks an opening of the part hole.

3. The manufacturing method for a cylinder head according to claim 2, wherein the between openings mask portion masks a region including the opening of the part hole and one of the at least one narrow region which is the closest to the opening of the part hole.

4. The manufacturing method for a cylinder head according to claim 1, wherein the film material particles are sprayed onto the entire region of the inner wall surface in a direction opposed to the matching surface with the cylinder block.

5. The manufacturing method for a cylinder head according to claim 1, wherein the at least one narrow region comprises a plurality of narrow regions which are divided into two groups in accordance with the shortest distance between the opening edges of the two adjacent port holes of the at least three port holes, and the between openings mask portion masks at least one region that is divided into a short distance group.

6. The manufacturing method for a cylinder head according to claim 1, wherein the inner wall surface includes at least two openings of two adjacent intake ports of the at least three port holes, and the between openings mask portion masks at least one region within the at least one narrow region, wherein the at least one region is a sandwiched region between the at least two openings of the adjacent intake ports.

7. The manufacturing method for a cylinder head according to claim 1, wherein the inner wall surface includes at least two adjacent exhaust ports, and the between openings mask portion masks at least one region within the at least one narrow region, and wherein the at least one region is a sandwiched region between the openings of the adjacent exhaust ports.

8. The manufacturing method for a cylinder head according to claim 1, wherein the at least one narrow region comprises a plurality of narrow regions, the between openings mask portion masks the plurality of narrow regions.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a diagram for describing a flow of a manufacturing method of a cylinder head of an embodiment of the present application;

(2) FIG. 2 is a schematic diagram for showing a region, after a machining of a step S2 of FIG. 1, to which a wall surface of a combustion chamber corresponds within a surface of a casting product of a cylinder head;

(3) FIG. 3 is a diagram for describing a step S5 of FIG. 1;

(4) FIG. 4 is a diagram for describing a step S5 of FIG. 1;

(5) FIG. 5 is a diagram for showing a part of a masking member which is attached to the casting product of the cylinder head;

(6) FIG. 6 is a diagram for describing a step S6 of FIG. 1;

(7) FIG. 7 is a diagram for describing a step S7 of FIG. 1;

(8) FIG. 8 is a diagram for describing an alternative masking member used in the step S5 of FIG. 1;

(9) FIG. 9 is a schematic diagram for showing a region, after a machining of a step S2 of FIG. 1, to which a wall surface of a combustion chamber corresponds within a surface of a casting product of a cylinder head; and

(10) FIG. 10 is a diagram for describing a part of the masking member in a state of being attached to the casting product of the cylinder head.

DETAILED DESCRIPTION

(11) Embodiments of the present application are described hereunder referring to figures. Note that elements that are common to the respective drawings are denoted by the same reference characters and a duplicate description thereof is omitted. Further, the present application is not limited to the embodiments described hereunder.

First Embodiment

(12) A first embodiment of the present application is described with reference to FIGS. 1 to 8.

Manufacturing Method for a Cylinder Head

(13) FIG. 1 is a diagram for describing a flow of a manufacturing method of a cylinder head (specifically, a cylinder head for a compression self-ignition type engine) of an embodiment of the present application. In this embodiment, at first, a casting of a cylinder head is carried out (step S1). In the step S1, a plurality of cores to form an inner spatial area of the cylinder head such as an intake port to attach an intake valve, an exhaust port to attach an exhaust valve and a water jacket are installed to predetermined positions of a plurality of dies to form an outer shape of the cylinder head. Then a base material (e.g., aluminum alloy) of the cylinder head is poured into the dies to be molded. Then a casting product (hereinafter simply referred to as cylinder head material) is removed from the dies while the cores are crushed to remove.

(14) Following the step S1, a machining of the cylinder head material is carried out (step S2). In the step S2, specifically, a hole for housing an injector (hereinafter referred to as an injector hole), holes for housing bolts to install the cylinder head into a cylinder block (hereinafter referred to as bolt holes) and valve guides for supporting the intake valve and the exhaust valve are formed with a drill.

(15) FIG. 2 is a schematic diagram for showing a region, after the machining of the step S2, to which a wall surface of a combustion chamber corresponds within the surface of the cylinder head material. As shown in FIG. 2, the injector hole 20 is formed on the central part of the cylinder head material 10 (more properly, the central part of a wall surface 10a of the surface of the cylinder head material 10). The intake ports 12 and 14 and the exhaust ports 16 and 18 are formed so as to surround this injector hole 20. The bolt holes are formed on the matching surface with the cylinder block located outside of the wall surface 10a shown in FIG. 2.

(16) Following the step S2, a washing of the machined cylinder head material is carried out (step S3). This step is carried out for the reason that if the cylinder head material contains foreign matters such as sand of the core occurred by the crush in the step S1 and cutting waste occurred by the machining in the step 2, the quality of a final product, i.e. an engine, will be declined. Another reason for the step S3 is to avoid an influence on a film formation in the step S6 described below. In the step S3, specifically, washings are injected to the intake port 12, the injector hole 20 and the like shown in FIG. 2 thereby foreign matters are removed therefrom.

(17) Following the step S3, a roughening a predetermined region of the surface of the cylinder head material (substrate surface) is carried out (e.g., water jet, sandblast, laser material processing, and the like) (step S4). This step is carried out for the reason that if the roughness of the predetermined region is intentionally deteriorating, a coherence power of the heat shield film formed thereon is improved due to an anchor effect. Here, the predetermined region is comparable to a film formation region, in particular, the whole region of the wall surface 10a shown in FIG. 2. Note that if the film formation region is a part of the wall surface 10a (e.g. a part of the surface around the injector hole 20), the predetermined region shall be reduced.

(18) Following the step S4, an attachment of the masking member is carried out (step S5). This step S5 is described with reference to FIG. 3 to FIG. 5. Note that the cylinder head material and the masking member are simplified in FIG. 3 for convenience of the explanation. As shown in FIG. 3, a plate-like masking member 30 is attached to the cylinder head material 10 in this step S5. FIG. 4 is a diagram for showing the cylinder head material 10 to which the masking member 30 is attached. A plurality of knock pins 32 are positioning pins which are inserted into the bolt holes through the masking member 30. By the positioning pins, the masking member 30 is positioned at a predetermined position within the surface of the cylinder head material 10 (more properly, the matching surface with the cylinder block 10b shown in FIG. 3) and the masking member 30 is appressed to the surface of the cylinder head material 10.

(19) FIG. 5 is a diagram for showing a part of the masking member which is attached to the casting product of the cylinder head. This figure describes a square area among four of the knock pins 32 shown in FIG. 4. As shown in FIG. 5, the masking member 30 comprises a mask portion 30a to mask the matching surface with the cylinder block, mask portions 30b, 30c, 30d and 30e to mask openings of the intake ports and the exhaust ports, and a mask portion 30f to mask a region which is sandwiched between the openings of the exhaust ports 16 and 18 shown in FIG. 2.

(20) The mask portion 30a is linked directly to the mask portions 30b, 30c, 30d and 30e without any steps, and the mask portion 30f is linked directly to both of the mask portions 30d and 30e without a step. Here, when two mask portions are linked without other mask portions, it is meant that the one mask portion is linked directly to the other mask portion. For example, the mask portion 30a is linked to the mask portion 30f through the mask portion 30d or 30e, but it is not true that the mask portion 30a is linked directly to the mask portion 30f. Note that the injector hole 20 is exposed in FIG. 5, where an exclusive masking member being independent of the masking member 30 will be inserted before the step S6 described below.

(21) The mask portion 30f shown in FIG. 5 masks a region including a narrow region A.sub.1 shown in FIG. 2, whose width being defined by a distance D.sub.EX1-EX2 between opening edges of the exhaust ports 16 and 18 is the shortest. It is preferable that the mask portion 30f masks a necessary minimum area including at least the narrow region A.sub.1, since heat shielding performance of a combustion chamber of an engine decreases when the mask portion 30f masks large area and the film formation region becomes small.

(22) Following the step S5, a film formation of the heat shield film is carried out (step S6). This step S6 is described with reference to FIG. 6. Note that the cylinder head material and the masking member are simplified in FIG. 6 for convenience of the explanation. As shown in FIG. 6, film material particles 36 (e.g., chrome-nickel steel-based ceramics particles, zirconia particles, and the like) on a carrier (e.g., plasma jet, compressed air, a fuel gas, an inert gas, and the like) are injected from a nozzle 34 in this step S6. During the injection from the nozzle 34, the nozzle 34 is reciprocated in a longitudinal direction of the cylinder head material 10 while a tip of the nozzle 34 is kept vertical to the surface of the masking member 30 (more properly, the matching surface with the cylinder block 10b). In this manner, a heat shield film having a desired thickness depending on heat properties (e.g. 50 to 200 m) is formed on the wall surface 10a. However, the tip of the nozzle 34 does not have to be vertical to the surface of the masking member 30 exactly and may incline to some extent. In this case, it is desirable to keep an injection direction of the film material particles 36 being vertical to the film formation region.

(23) Following step S6, a detaching of the masking member 30 is carried out (step S7). This step S7 is described with reference to FIG. 7. Note that the cylinder head material and the masking member are simplified in FIG. 7 for convenience of the explanation. As shown in FIG. 7, the masking member 30 is detached from the cylinder head material 10 on which a heat shield film 38 is formed. Note that before the detachment, the knock pins 32 shown in FIG. 4 are removed from the bolt holes. Also, the exclusive masking member mentioned above is detached from the injector hole before or after the detachment of the masking member 30.

(24) The area of the narrow region A.sub.1 shown in FIG. 2 is smaller than areas of the other regions within the wall surface 10a. And therefore, if a heat shield film is formed on the narrow region A.sub.1, the film has less sticking force therewith. Thus, the heat shield film on the narrow region A.sub.1 is easily peeled during detachment of the masking member in the step S7 or during the finish processing in the step S8 discussed below. In this regard, according to the masking member 30 described with FIG. 5, the narrow region A.sub.1 is masked by the mask portion 30f. That is, film formation on the narrow region A.sub.1 where the peeling of the heat shield film tends to take place can be avoided. Therefore, an occurrence of the peeling of the heat shield film and thus, a high-quality heat shield film can be obtained.

(25) Also, in the masking member 30, the mask portions 30a to 30f are united to a single masking member, which helps to simplify the attachment in the step S4 and the detachment in the step S6. Compared with a case where the mask portion 30f is separated from the mask portions 30a to 30e, the united single masking member makes it possible to save a lot of trouble in the removal of the adhered film material particles. These advantages will help to promote reuse of the masking member 30 and also to enhance productivity of the cylinder head.

(26) Referring back to FIG. 1, a finish processing of the surface of the heat shield film is carried out after the step S7 (step S8). In this step S8, for example, a smoothing of the film surface and adjustment of the film thickness are carried out by a cutting with end mills and the like or a plane grinding with a whetstone. Parallel to this process, a machining of unprocessed portions such as the intake ports which were not processed in the machining of the step S2 and a formation surfaces for seating umbrella portions such as umbrella portions of the intake valves are carried out.

(27) Following the step S8, a final washing of the cylinder head material is carried out (step S9). In the step S8, specifically, washings are injected to the intake port 12, the injector hole 20, the film formation region and the like shown in FIG. 2 and thereby foreign matters such as cut chips generated in the finish processing and the machining described in the step S8 are removed therefrom.

(28) Following the step S9, an inspection of the cylinder head material is carried out (step S10). In the step S9, for example, inspections of the heat shield film and the shapes of the intake ports and the exhaust ports are carried out. After the step S10, the cylinder head which has the heat shield film on the wall surface 10a shown in FIG. 2 can be manufactured.

(29) Note that in the first embodiment mentioned above, the intake ports 12 and 14 and the exhaust ports 16 and 18 shown in FIG. 2 correspond to the port holes of the present application. The mask portion 30a shown in FIG. 2 corresponds to the matching surface mask portion of the present application. The mask portions 30b to 30e shown in FIG. 2 correspond to the port hole mask portions of the present application. The mask portion 30f shown in FIG. 2 corresponds to the between openings mask portion of the present application.

(30) Further, the steps from the step S1 through the step S4 shown in FIG. 1 correspond to the preparation step of the present application. The step S5 shown in FIG. 1 corresponds to the attaching step of the present application. The step S6 shown in FIG. 1 corresponds to the film formation step of the present application. The step S7 shown in FIG. 1 corresponds to the detaching step of the present application.

Other Manufacturing Methods for a Cylinder Head

(31) In the first embodiment mentioned above, the region including the narrow region A.sub.1 is described, whose width is the shortest distance D.sub.EX1-EX2 between opening edges of the exhaust ports 16 and 18. However, as shown in FIG. 2, the wall surface 10a includes regions sandwiched between openings of the intake ports 12 and 14, between openings of the intake port 12 and the exhaust port 16, and between openings of the intake port 14 and the exhaust port 18 as well as the region sandwiched between the openings of the exhaust ports 16 and 18. Therefore, a masking member 40 shown in FIG. 5 may be used in the step S5.

(32) FIG. 8 is a diagram for showing a part of an alternative masking member which is attached to the casting product of the cylinder head. A masking member 40 shown in FIG. 8 is configured to mask all regions sandwiched between openings of two adjacent ports. Specifically, the masking member 40 comprises, in addition to the mask portions 30a to 30f described with FIG. 5, a mask portion 30g to mask a region which is sandwiched between the openings of the intake ports 12 and 14 shown in FIG. 2, a mask portion 30h to mask a region which is sandwiched between the openings of the intake port 12 and the exhaust port 16, and a mask portion 30i to mask a region which is sandwiched between the openings of the intake port 14 and the exhaust port 18.

(33) The mask portions 30g to 30i have the same basic structure as the mark portion 30f. That is, the mask portion 30g is linked directly to both of the mask portions 30b and 30c without a step. The mask portion 30g masks a region including a narrow region A.sub.2, as shown in FIG. 2, whose width being defined by a distance D.sub.IN1-IN2 between opening edges of the intake ports 12 and 14 is the shortest. The mask portion 30h is linked directly to both of the mask portions 30b and 30d without a step. The mask portion 30h masks a region including a narrow region A.sub.3 shown in FIG. 2, whose width being defined by a distance D.sub.IM1-EX1 between opening edges of the intake port 12 and the exhaust port 16 is the shortest. The mask portion 30i is linked directly to both of the mask portions 30c and 30e without a step. The mask portion 30i masks a region including a narrow region A.sub.4 shown in FIG. 2, whose width being defined by a distance D.sub.IN2-EX2 between opening edges of the intake port 14 and the exhaust port 18 is the shortest.

(34) In the first embodiment mentioned above, the masking member is described to mask the non-film formation region of the wall surface of the combustion chamber on which two intake ports and exhaust ports are formed respectively. However, the number of these ports are not limited thereto. For example, three intake ports and exhaust ports may be formed respectively on the combustion chamber. Alternatively, four intake ports and exhaust ports may be formed respectively on the combustion chamber. Alternatively, the number of the intake port may be different from the number of the exhaust port, for example, two intake ports and one exhaust port may be formed on the combustion chamber. In either case, the same effect as the first embodiment can be obtained if a masking member for practical use is selected by considering a narrow region whose width being defined by a distance between opening edges of two adjacent ports among at least three ports is the shortest, restoring balance between the area of the narrow region and heat shielding performance as necessary, and judging whether a mask portion like the mask portion 30f described with FIG. 5 should be applied.

(35) For example, the masking member for practical use is selected as follows: dividing the narrow regions A.sub.1 to A.sub.4 into two groups consisting of a long distance group and a short distance group in accordance with the shortest distance between opening edges of two adjacent port holes among four port holes shown in FIG. 2 (i.e. the distance D.sub.EX1-EX2, D.sub.IN1-IN2, D.sub.IN1-EX1, D.sub.IN2-EX2), determining to mask at least one region which is divided into the short distance group.

Second Embodiment

(36) A second embodiment of the present application is described with reference to FIGS. 9 and 10.

(37) Note that since a flow of a manufacturing method of the second embodiment is basically the same as that of the first embodiment described with FIG. 1, a description about the flow that overlaps with the first embodiment will be omitted.

Manufacturing Method for a Cylinder Head

(38) A manufacturing method of the second embodiment, a hole for housing a glow plug-integrated cylinder pressure sensor (hereinafter referred to as a CPS hole) is formed on a predetermined position of the cylinder head material at the machining of the step S2 described with FIG. 1. FIG. 9 is a schematic diagram for showing a region, after the machining of the step S2, to which the wall surface of the combustion chamber corresponds within the surface of the casting product of the cylinder head. As shown in FIG. 9, in addition to the intake ports 12 and 14 and the exhaust ports 16 and 18, a CPS hole 22 is formed on the central part of a surface of a cylinder head material 50 (more properly, the central part of a wall surface of the combustion chamber).

(39) In the manufacturing method of the second embodiment, a masking member comprising a mask portion to mask an opening of the CPS hole is used in the step S5 shown in FIG. 5. FIG. 10 is a diagram for describing a part of the masking member in a state of being attached to the casting product of the cylinder head. This figure describes the square area among four of the knock pins 32 shown in FIG. 4. As shown in FIG. 10, the masking member 60 comprises, in addition to the mask portions 30a to 30e, a mask portion 30j to mask an opening of the CPS hole 22 shown in FIG. 9.

(40) The mask portion 30j have the same basic structure as the mark portion 30g described with FIG. 8. That is, the mask portion 30j is linked directly to both of the mask portions 30b and 30c without a step. The mask portion 30j masks a region including the narrow region A.sub.2, as shown in FIG. 2, whose width being defined by the distance D.sub.IN1-IN2 between opening edges of the intake ports 12 and 14 is the shortest.

(41) The mask portion 30j shown in FIG. 10 masks both the narrow region A.sub.2 shown in FIG. 9 and a CPS region A.sub.5 shown in FIG. 9 which is a region including an opening of the CPS hole 22. The CPS region A.sub.5 is the closest region to the narrow region A.sub.2 among the narrow regions A.sub.1 to A.sub.4. It is preferable that the mask portion 30j masks a necessary minimum area including at least the narrow region A.sub.2 and the CPS region A.sub.5, since heat shielding performance of a combustion chamber of an engine decreases when the mask portion 30j masks large area and the film formation region becomes small.

(42) The area of the narrow region A.sub.2 or the CPS region A.sub.5 shown in FIG. 9 is smaller than area of the other regions within the wall surface 50a. And therefore, if a heat shield film is formed on the narrow region A.sub.2 or the CPS region A.sub.5, the film has less sticking force therewith. Thus, the heat shield films on these regions A.sub.2 and A.sub.5 are easily peeled during detachment of the masking member in the step S7 or during the finish processing in the step S8. In this regard, according to the masking member 60 described with FIG. 10, these regions A.sub.2 and A.sub.5 are masked by the mask portion 30j. That is, film formation on the narrow region A.sub.1 or the CPS region A.sub.5, where the peeling of the heat shield film tends to take place can be avoided. Therefore, an occurrence of the peeling of the heat shield film and thus, a high-quality heat shield film can be obtained.

(43) Note that in the second embodiment mentioned above, the CPS hold 22 shown in FIG. 9 corresponds to the part hole of the present application.

Other Manufacturing Methods for a Cylinder Head

(44) In the second embodiment mentioned above, the glow plug-integrated cylinder pressure sensor is housed in the cylinder head. However, a glow plug and a cylinder pressure sensor may be separately housed in the cylinder head. In this case, a hole for housing the glow plug and a hole for housing the cylinder pressure sensor may be formed separately on each region sandwiched between openings of two adjacent ports among the intake ports and the exhaust ports. Therefore, the same effect as the second embodiment can be obtained if a masking member comprising a mask portion to mask the opening of the hole for housing the glow plug and a mask portion to mask the opening of the hole for the cylinder pressure sensor and two mask portions, both of which is linked directly to two mask portions located both side of the hole for housing the glow plug or the cylinder pressure sensor is used.

(45) In the second embodiment mentioned above, the cylinder head is described as a cylinder head for a compression self-ignition type engine. However, the cylinder head may be a cylinder head for a spark ignition type engine. In the spark ignition type engine, a spark plug is housed in the cylinder head substitute for the glow plug-integrated cylinder pressure sensor. The spark plug is generally housed on the center portion of the wall surface of the combustion chamber (i.e. the position of the injector hole 20 shown in FIG. 9). When two spark plugs are housed, however, one of the spark plugs may be housed in a hole between the two intake ports like the glow plug-integrated cylinder pressure sensor mentioned above. In this case, the same effect as the second embodiment can be obtained if a masking member comprising a mask portion to mask an opening of the hole for housing the one of the spark plugs which is linked directly to the mask portions to mask the intake ports is used.