JP2009235954A - Cylinder head reinforcement member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a durable cylinder head reinforcement member. <P>SOLUTION: A plurality of valve seat parts arranged in a flat plate shape and connection parts connecting those are integrally formed into an iron base sintered body. Formation of a crack between the valve seats (between valves) is prevented thereby and a cylinder head is made durable. It is preferable to install the cylinder head reinforcement member in the cylinder head by an insert casting method. The insert casting method provides an advantage that the reinforcement member can be thinned. It is also preferable to provide a plurality of projection parts on a surface at a valve seating surface side. Load of cutting after installation into a cylinder head body can be reduced thereby. It is also preferable to set at least surface roughness of outer circumference side surface to Rz 20-100 μm from a point of view of improving adhesion with the cylinder head body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reinforcing member including a valve seat mounted on a cylinder head of an internal combustion engine, and more particularly to prevention of cracks in a cylinder head valve portion.

  A valve seat on which an intake / exhaust valve is seated is attached to a cylinder head of an internal combustion engine mainly by press fitting. In recent years, an internal combustion engine provided with a large number of valves has been used to improve the performance of the internal combustion engine. Along with this, the number of valve seats has also increased, and there has been a problem of increased man-hours and material costs for manufacturing valve seats. In order to solve such a problem, an integrated valve seat has been proposed.

  For example, in Patent Document 1, a valve seat is constituted by a pair of valve seats in which a valve seat portion of one intake valve and a valve seat portion of one exhaust valve are connected and integrated in a glasses shape, and the valve seat is a cylinder. A four-valve internal combustion engine in which a spark plug hole is provided between a pair of valve seats while being press-fitted into a head has been proposed. According to the technique described in Patent Document 1, it is possible to improve the manufacturability of the valve seat and reduce the material cost, to suppress an increase in the combustion chamber wall temperature, and to remove the adverse effect on the spark plug.

  Further, in Patent Document 2, an arc-shaped notch is provided in the valve portion of the cylinder head, and the intake system valve seat and the exhaust system valve seat are integrally formed at the position of the valve portion, so that A cylinder head of an internal combustion engine that is press-fitted is described. According to the technique described in Patent Document 2, the valve seat does not fall off from the cylinder head, and cracks do not occur in the inter-valve portion.

  However, since the techniques described in Patent Documents 1 and 2 are based on the premise that the valve seat is press-fitted into the cylinder head, internal stress is generated during the press-fitting, and the cylinder head is caused by a difference in thermal expansion, a pressure in the combustion cylinder, or the like. The problem of deformation and cracking between the valves remained. Further, the techniques described in Patent Documents 1 and 2 have a problem that the valve seat shape is complicated, and it is difficult to drill a hole in the cylinder head for press-fitting.

In Patent Document 3, valve seats are connected by a connecting member in a direction connecting exhaust passages to form an integral valve insert, and the tightening margin between the valve insert and the cylinder head is compared with the width direction of the connecting member. A cylinder head structure is described in which the valve insert is fitted to the cylinder head with a large setting in the connecting direction of the connecting member.
Japanese Utility Model Publication No. 61-51415 Japanese Utility Model Publication No. 61-1642 No. 05-7450

  However, since the technique described in Patent Document 3 is based on the premise that the valve seat is press-fitted into the cylinder head in the same manner as the techniques described in Patent Documents 1 and 2, internal stress occurs during press-fitting, and further heat There has been a problem that the cylinder head is deformed due to an expansion difference, an in-cylinder pressure or the like, and a crack is generated between the valves. Moreover, since the shape of the hole processing for press-fitting is complicated, there is a problem that it involves considerable difficulty.

  Recently, from the viewpoint of reducing the weight of an automobile body, an internal combustion engine made of aluminum alloy has become the mainstream, and there is a strong demand for higher efficiency of the internal combustion engine, and the internal pressure of the combustion cylinder further increases. It has become a trend. For this reason, the stress in the inter-valve part of the cylinder head increases, and even if the techniques described in Patent Documents 1 to 3 are used, the inter-valve part is made of an aluminum alloy, so that the inter-valve part still remains. There has been a problem that the cylinder head tends to crack frequently.

  The present invention has been made in view of such a situation, and proposes a cylinder head reinforcing member that can prevent cracks in the valve-interval portion and further prevent the valve seat from falling off, and has superior durability. With the goal. Another object of the present invention is to propose a cylinder head reinforcing member with excellent durability that can be applied to an internal combustion engine (for example, a diesel engine) having a high combustion cylinder pressure and a large heat load. .

  In order to achieve the above-mentioned object, the present inventors diligently studied strength reinforcement between valve seat portions (valve portion). As a result, it was conceived that the space between the valve seats (between the valves) should be formed of an iron-based sintered body, which is the same material as the valve seat material, instead of the aluminum alloy of the cylinder head material. It has been found that by forming the intervalve portion with an iron-based sintered body, the strength between the valve seats (interval between the valves) is increased, the durability is remarkably improved, and the occurrence of cracks and the like can be easily prevented.

The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
(1) It has a plurality of valve seat portions arranged in a flat plate shape and a connecting portion that connects the plurality of valve seat portions, and the connecting portion and the plurality of valve seat portions are integrally configured. A cylinder head reinforcing member, which is an iron-based sintered body.

(2) The cylinder head reinforcing member according to (1), wherein the cylinder head reinforcing member is a member attached to the cylinder head by a cast-in method.
(3) The cylinder head reinforcing member according to (2), wherein a plurality of convex portions are arranged on the surface on the valve contact surface side.
(4) The cylinder head reinforcing member according to (1) to (3), wherein at least the surface roughness of the outer peripheral side surface is 20 to 100 μm in Rz defined in JIS B 0601-1994.

(5) The cylinder head reinforcing member according to any one of (1) to (4), wherein the total number of the plurality of valve seat portions and the nozzle or spark plug hole portion is three or more.
(6) The cylinder head reinforcing member according to any one of (1) to (5), wherein the valve seat portion and the connecting portion have a structure having two layers in a thickness direction.

  According to the present invention, there is no risk of dropping off the valve seat, cracking between the valve seats (between the valves) can be prevented, the durability of the cylinder head is remarkably improved, and a remarkable industrial effect is achieved. Moreover, according to this invention, there exists an effect that the outstanding durability especially for diesel engines can be ensured. In addition, there is an effect that the manufacturing load of the valve seat can be reduced.

The cylinder head reinforcing member of the present invention has a plurality of valve seat portions arranged in a flat plate shape and a connecting portion that connects them, and the plurality of valve seat portions and the connecting portion are integrally configured. It becomes. The valve seat portion is a hole for seating the intake / exhaust valve, and a plurality, preferably three or more, are arranged corresponding to the number of valves.
An example of the cylinder head reinforcing member 1 of the present invention is shown in FIG. The example shown in FIG. 1 is an example of a 4-valve cylinder head reinforcing member in which four valve seat portions 11 are arranged in a flat plate shape. In the example shown in FIG. 1, the valve seat portion 11 and the connecting portion 12 have different thicknesses, and the connecting portion 12 is thinner than the valve seat portion 11. In the present invention, the present invention is not limited to this. As shown in FIG. 2, there is no problem even if the valve seat portion 11 and the connecting portion 12 have the same thickness. In the cylinder head reinforcing member 1 of the present invention, a nozzle or a spark plug (not shown) may be provided at an appropriate position of the connecting portion 12.

  The cylinder head reinforcing member 1 of the present invention is made of an iron-based sintered body in which the valve seat portion 11 and the connecting portion 12 are integrally formed of the same material. As a result, the connecting portion is composed of the same iron-based sintered body as the valve seat portion, and the connecting portion is higher than the conventional technology in which the space between the valve seat portions (between the valves) is made of a cylinder head material. The strength is increased, cracking between the valve seat portions can be prevented, and the durability of the cylinder head reinforcing member is significantly improved.

  As the iron-based sintered body used here, any iron-based sintered body having a composition conventionally used for valve seats can be suitably used. Among these, an iron-based sintered body in which hard particles are dispersed in the matrix phase of the iron-based sintered alloy is preferable. Further, the iron-based sintered body may be an iron-based sintered body having a two-layer structure. The two-layer structure has two layers in the thickness direction, that is, an iron-based sintered body excellent in wear resistance in which hard particles are dispersed in the base phase of the iron-based sintered alloy on the surface side (outer layer) per valve. And a structure in which the inner layer is an iron-based sintered body containing no hard particles can be exemplified.

  The cylinder head reinforcing member of the present invention has the above-described configuration, and is fitted into an intake / exhaust port in contact with a combustion chamber of a cylinder head body of an internal combustion engine, and preferably is casted. In the present invention, in particular, by adopting the cast-in method, there is less stress acting on the cylinder head reinforcing member than in the press fitting method, and the thickness of the cylinder head reinforcing member can be reduced.

  In the cylinder head reinforcing member of the present invention, it is preferable that at least the surface of the side surface (outer peripheral surface) is subjected to shot blasting to be roughened. In particular, it is preferable when mounted on the main body by a cast-in method. By roughening the outer peripheral surface of the reinforcing member, the adhesion with the cylinder head body is improved, and it is possible to easily prevent the dropout. In the present invention, the surface roughness of the outer peripheral surface is preferably adjusted so as to be 20 to 100 μm in Rz defined in JIS B 0601-1994. When the surface roughness is out of the above range, the adhesion with the cylinder head body is lowered, and the cylinder head reinforcing member is easily dropped.

  Moreover, in this invention, it is preferable to arrange | position the some convex part 13 as shown in FIG. 3 on the surface by the side of the valve | bulb contact surface of a cylinder head reinforcement member. By arranging multiple convex parts 13, the valve seat after mounting on the cylinder head can be processed only by the convex part, and there is almost no need to machine the valve seat surface, and the load on the processing tool is reduced. As a result, the amount of wear of the processing tool can be reduced, the processing cost can be reduced, the processing time can be shortened, and the productivity can be improved. In addition, it is preferable from a viewpoint of machining allowance that the height of a convex part shall be about 0.5-1.0 mm. Moreover, it is preferable from a viewpoint of the stability at the time of a set before casting that the number of convex parts shall be about 3-5 pieces.

Next, a preferred method for producing the cylinder head reinforcing member of the present invention will be described.
First, in order to obtain a desired matrix phase composition, alloy element powder is mixed with pure iron powder, or alloy element powder is further mixed with iron-based powder, or hard particle powder so as to obtain a desired dispersion amount, or Furthermore, a predetermined amount of a solid lubricant is blended, mixed and kneaded to obtain a mixed powder, and the mixed powder is filled into a mold having a predetermined size and shape, compression molded, and then sintered, followed by a cylinder head having a predetermined size and shape. It is preferable to use a reinforcing member. The mixed powder is subjected to a compression molding-sintering step to obtain a primary sintered body, and the primary sintered body is further subjected to a compression molding-sintering step to obtain a sintered body (cylinder head reinforcing member). A twice-repetitive compression molding-sintering process may be employed. In the case of a two-layer structure, the mixed powder should be mixed with each layer composition, filled in a mold so as to have two layers with a predetermined thickness, compression molded, and then sintered. preferable.

Example 1
The raw material powder is filled into a mold, compression molded at a surface pressure of 6 ton / cm ² to form a green compact, and then the green compact is sintered at 1160 ° C. in a non-oxidizing atmosphere to be iron-based sintered. The body (cylinder head reinforcing member) was used. The iron-based sintered body (cylinder head reinforcing member) is composed of four valve seat portions of (a) the shape shown in FIG. 1, (b) the shape shown in FIG. 2, and (c) the shape shown in FIG. A cylinder head reinforcing member having As shown in Table 1, in the shape shown in FIG. 1, the thickness a of the valve seat is set to 4 mm or 7 mm, and the thickness b of the connecting portion is set to 2 mm, whereas in the shape shown in FIG. The thickness a of each of the part and the connecting part was 4 mm. Further, in the shape shown in FIG. 3, the thickness a of the valve seat part and the connecting part is 4 mm, and the valve seating side surface has five convex parts (c = 0.5 mm). In addition, as shown in Table 1, the minimum distance (valve distance) between the valve seat portions 11 was changed between 2 and 5 mm.

  The obtained iron-based sintered body (cylinder head reinforcing member) 1 is made of an aluminum alloy cylinder head equivalent material 2 (size: thickness 30 mm) so that the valve contact surface side is the lower surface as shown in FIG. × 120mm × 120mm). After casting, flattening was performed to polish the flat surface of the valve contact surface. In addition, when the iron-based sintered body (cylinder head reinforcing member) having the shape shown in FIG. 3 was used, the projections were cut and flattened.

  For comparison, a valve seat having the same size as the valve seat portion of the cylinder head reinforcing member of the present invention (thickness: 7 mm, outer diameter: 30 mmφ) was prepared using a mixed powder having the same composition as described above. Separately from this, an aluminum alloy cylinder head equivalent material 2 (size: thickness 30 mm × 120 mm × 120 mm) in which four valve seat mounting holes were formed was prepared. Then, the size of the hole of the cylinder head equivalent material and the outer diameter of the valve seat are adjusted so that the tightening allowance of the valve seat is 80 μm, and these valve seats are connected to the cylinder head equivalent material as shown in FIG. Each of the two holes was pressed into a comparative example.

An adhesion test and a heating / cooling test were performed on the cylinder head equivalent material (comparative example) into which the valve seat was press-fitted and the cylinder head equivalent material (invention example) in which the cylinder head reinforcing member was cast. The test method was as follows.
(1) Adhesion test The obtained cylinder head equivalent material 2 (casting material) is exposed at the upper and lower surfaces of the cylinder head reinforcing member 1 as shown in FIG. Was processed into a test piece having a shape exposed on the upper and lower surfaces. Then, as shown in FIG. 5, both ends of the test piece are supported by the support base, a load is applied to the cylinder head reinforcing member 1, and the load (N) at which the cylinder head reinforcing member 1 falls out of the cylinder head equivalent material is measured. The adhesion was evaluated. Further, in the comparative example in which the valve seat was press-fitted into the cylinder head equivalent material, a load was applied to the press-fitted valve seat alone, and similarly, the load by which the valve seat fell off was measured to evaluate the adhesion.

(2) Heating / cooling test Heating temperature of the obtained cylinder head equivalent material to 300 ° C, heating process for 15 minutes at the heating temperature, and cooling process to cool from the heating temperature to water and cool to room temperature The thermal cycle consisting of was repeated up to 50 times until cracks occurred between the valve seat parts (between valves). It was evaluated that the greater the number of thermal cycle repetitions until cracks occur between valve seat parts (between valves), the better the durability.

  The obtained results are shown together in Table 1.

In all of the examples of the present invention, compared to the comparative example (press-fit material), the period (the number of thermal cycles) until the crack occurs between the valve seats is significantly increased, and the durability is improved. Further, the inventive example has a higher punching load and improved adhesion than the comparative example (press-fit material). In particular, in the example of the present invention in which the outer peripheral surface is roughened, the drawing load increases and the adhesion is remarkably improved.
(Example 2)
The machinability of the cylinder head equivalent materials No. 5 and No. 9 (casting materials) manufactured in Example 1 was compared. Cylinder head equivalent material No. 9 is a cylinder head reinforcing member in which a plurality of convex portions are formed on the valve contact surface side, and No. 5 is a cylinder head reinforcing member without a convex portion. It is. For these cylinder head equivalent materials, the valve contact surface side plane shown in Fig. 6 is as follows: Machine used: Milling machine (blade diameter: 150mmφ)
Tool used: Carbide tip Rotation speed: 800rpm
Feed rate: 0.05mm / rev
Cutting depth: 1.0mm
The tool wear after 5 passes was investigated. As a result, in the cylinder head equivalent material No. 5 using the cylinder head reinforcing member without the convex portion, the wear amount of the tip is 150 μm, whereas the cylinder head equivalent material using the cylinder head reinforcing member having the convex portion is equivalent. In material No. 9, it was 20 μm. It can be seen that the processing load on the valve contact surface side plane is significantly reduced by providing the cylinder head reinforcing member with the convex portion.

It is explanatory drawing which shows an example of the cylinder head reinforcement member of this invention. It is explanatory drawing which shows an example of the cylinder head reinforcement member of this invention. It is explanatory drawing which shows an example of the cylinder head reinforcement member of this invention. It is explanatory drawing which shows the cross section of the cylinder head equivalent material which cast the cylinder head reinforcement member used in the Example. It is explanatory drawing which shows an adhesiveness test method typically. It is explanatory drawing which shows typically the state which mounted | wore the cylinder head equivalent material by press-fitting.

Explanation of symbols

1 Cylinder head reinforcement member 2 Cylinder head equivalent material
11 Valve seat
12 Connecting part
13 Convex

Claims (6)

  A plurality of valve seat portions arranged in a flat plate shape and a connecting portion for connecting the plurality of valve seat portions, and the connecting portion and the plurality of valve seat portions are integrally configured. A cylinder head reinforcing member which is an iron-based sintered body.   The cylinder head reinforcing member according to claim 1, wherein the cylinder head reinforcing member is a member attached to the cylinder head by a cast-in method.   The cylinder head reinforcing member according to claim 1 or 2, wherein a plurality of convex portions are arranged on a surface on a valve contact surface side.   The cylinder head reinforcing member according to any one of claims 1 to 3, wherein the surface roughness of at least the outer peripheral surface is 20 to 100 µm in Rz defined in JIS B 0601-1994.   The cylinder head reinforcing member according to any one of claims 1 to 4, wherein the total of the plurality of valve seat portions and the nozzle or spark plug hole portion is three or more.   6. The cylinder head reinforcing member according to claim 1, wherein the valve seat portion and the connecting portion have a structure composed of two layers in the thickness direction.

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