JP3409301B2 - Reciprocating member - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating member. More specifically, the present invention relates to a reciprocating member that uses a highly rigid iron-based composite material and has a high degree of freedom in design.

[0002]

BACKGROUND OF THE INVENTION There are a wide variety of machines, but many utilize reciprocating motion. For example, a reciprocating engine (hereinafter simply referred to as "engine"), a machine tool planing machine, a loom (for example, a heddle, a reed portion), a sewing machine (for example, a needle, a table portion),
There are air-conditioning compressors (for example, piston parts) and printers (for example, head parts) for automobiles and the like.

These reciprocating motion devices are provided with various reciprocating motion members depending on their types, but any reciprocating motion member is subjected to inertial force as long as it reciprocates.
This inertial force F is given by F = -ma, where m is the inertial mass of the reciprocating member and its acceleration is a, and is determined by the inertial mass m of the reciprocating member and its acceleration a. The smaller the inertial force F, the smaller and faster the reciprocating member, and the more compact and faster the reciprocating device, the easier it is to improve responsiveness and performance. Needless to say, if the acceleration a or the inertial mass m can be reduced, the inertial force F can be reduced. Therefore, first, these will be examined.

Acceleration a The acceleration a occurs more or less as long as it is a reciprocating member. When the acceleration a of the reciprocating member increases, the acting inertial force F also increases, and the reciprocating member naturally increases in size in order to secure strength and the like. Moreover, the inertial mass is increased accordingly, and a vicious cycle in which the inertial force F is further increased may occur. Therefore, in a normal reciprocating device, a reciprocating motion is controlled by providing a buffer (ramp) region or the like so that the acceleration a does not become extremely large.
However, if the acceleration a is reduced, the movement of the reciprocating member becomes sluggish and the performance of the reciprocating device is deteriorated. Therefore, there is a limit to the reduction of the acceleration a. There are also reciprocating members, such as engine pistons, for which it is difficult to control the acceleration a acting on them mechanically. Further, in the case of a piston or the like, when the crank radius is r and the angular velocity is ω, the acting acceleration a is proportional to r · ω ² . If the engine speed is increased in order to improve the performance of the engine, the acceleration a will be rapidly increased. As described above, it is not always easy to reduce the acceleration, and in particular, it is difficult to reduce the acceleration while maintaining and improving the performance of the reciprocating device.

Inertia mass m As described above, the acceleration a can be reduced by reducing the inertia mass m. The reduction of the inertial mass m is achieved by making the reciprocating member and the reciprocating device light and compact.
It is possible to reduce drive loss, improve performance, improve responsiveness, and the like. Therefore, reduction (weight reduction) of the inertial mass m is highly desired. By the way, the amount of deformation of the reciprocating member may be severely limited in order to prevent interference with other members and improve performance. For example, when the amount of deformation of the reciprocating member increases, the positional accuracy (operation timing, etc.) during the reciprocating motion deteriorates, and the performance of the reciprocating device may deteriorate. Further, if the amount of deformation of the reciprocating member increases and a large secondary stress acts on the supporting member, it may be necessary to reinforce the supporting member. Therefore, the reciprocating member is often required to be lightweight and to suppress / reduce the amount of deformation.

[0006]

However, achieving both such a reduction in weight and suppression / reduction of the amount of deformation is
It used to be difficult. For example, in order to reduce the weight of the reciprocating member, it is conceivable to change the material thereof from steel to light alloy (such as aluminum alloy and titanium alloy). However, such a material change significantly reduces the rigidity (Young's modulus) to less than half, and unless the shape of the reciprocating member is significantly changed, the amount of deformation increases significantly. On the other hand, if the shape is drastically changed in order to suppress or reduce the amount of deformation, the reciprocating member generally increases in size, which hinders downsizing of the reciprocating device. Therefore, the present inventor has focused on reducing the weight of the reciprocating member and suppressing / reducing the amount of deformation. In other words, it was considered to provide a reciprocating member that provides a great degree of freedom in designing both weight reduction and suppression / reduction of the amount of deformation, and further improve the performance of the reciprocating device. Therefore, before providing such a reciprocating member, first, the following study was conducted.

(1) Weight Reduction As described above, since a large inertial force acts on the reciprocating member, weight reduction is desired. For example, taking an engine as an example, the reciprocating inertia mass between the piston (including the piston ring) and the piston pin (total)
Assuming that m is m, the stroke of the piston is 2r, and the distance between the centers of the connecting rods is 1, the maximum value of the inertial force F applied to the small end of the connecting rod is mrω ² (1 + r /
l). More specifically, m = 300 g, r = 80
mm, ω = 733 rad / s (7000 rpm), r /
When 1 = 0.25, approximately F = 16000N. If the inertia mass of the piston / pin could be reduced by 1g,
The inertial force is reduced by about 54N. This can reduce the force acting on the connecting rod and the crank shaft, and make them lighter and more compact, and further, the engine itself can be made lighter and more compact. Moreover,
When the response of the engine is important like in automobiles and motorcycles, the reduction of the reciprocating inertial mass can further improve the response, so that the performance of the engine is also improved in terms of fuel consumption and sensitivity.

However, as described above, in consideration of the deformation, it is possible to reduce the weight and size of the reciprocating member.
It used to be difficult. This is because it is effective to use a low-density material for reducing the weight of the reciprocating member, but as long as a conventional material is used, a decrease in the density ρ also means a decrease in the Young's modulus E. Specifically, as shown in FIG. 1, the decrease in the density ρ and the decrease in the Young's modulus E are in a substantially proportional relationship, and there is almost no difference in the specific Young's modulus E / ρ in the conventional metal material. Therefore, this density ρ and Young's modulus E
If a new material that breaks the relationship with is obtained, it is possible to achieve both weight reduction of the reciprocating member and suppression / reduction of the amount of deformation, and to provide a reciprocating member having a large degree of design freedom. Become. For example, if the Young's modulus E is large, even if the density ρ is about the same as the conventional one, it is possible to reduce the weight and size of the reciprocating member while considering the deformation.

(2) Deformation Since various forces act on the reciprocating member in addition to the inertial force described above, its deformation is also diverse. For example, stretch,
There are deformations such as bending, twisting and buckling. The amount of deformation of the reciprocating member is often regulated from the viewpoint of ensuring the motion accuracy and preventing interference with other members. Here, a piston pin, a connecting rod, and a rocker arm, which are reciprocating members of the engine, are taken as an example, and their modifications will be specifically described.

(A) Piston Pin The piston pin is a member that connects the piston and the small end of the connecting rod, and is generally a cylindrical member. The piston pin and the piston are reciprocating members that reciprocate at high speed according to the engine speed. As the deformation of the piston pin, for example,
Deflection as shown in FIG. 8 (image diagram) can be considered. As a case of deformation as shown in FIG. 8, it is considered that the piston top surface receives a large explosive force near the top dead center or, conversely, a downward inertial force acts on the piston near the bottom dead center. . Of course, in the vicinity of the top dead center where the exhaust stroke changes to the intake stroke, the piston pin may bend in the opposite direction. In any case, it is considered that a large bending moment acts on the piston pin near the top and bottom dead centers and the piston pin is bent. If this deflection becomes too large, the contact and surface pressure distribution between the inner peripheral surface of the pin boss of the piston and the outer peripheral surface of the piston / pin become non-uniform, causing early wear and scuffing. Further, since a large secondary stress is applied to the pin boss of the piston, it is necessary to reinforce the pin boss portion, resulting in an increase in weight of the piston.

Next, the amount of flexure δ of the piston pin will be examined in terms of material dynamics. The flexure amount δ of the piston / pin is the flexural rigidity EI (E: longitudinal elastic modulus (Young's modulus),
I: Second moment of area (= π (d ₀ ⁴ −d ₁ ⁴ ) / 6
4), d ₀ : outer diameter of piston pin, d ₁ : inversely proportional to inner diameter of piston pin), so that bending amount EI can be reduced by increasing bending rigidity EI. That is, the second moment of area I or the Young's modulus E may be increased.

Here, increasing the second moment of inertia I of the piston pin means increasing its outer diameter d ₀ , resulting in an increase in the inertial mass of the piston pin. As its inertial mass increases, so does the inertial force acting on the piston pin and connecting rod.
As a result, it is necessary to reinforce the connecting rod and the weight of the connecting rod is increased. As described above, it is not preferable to increase the bending rigidity EI from the viewpoint of shape, because not only the weight (inertial mass) of one reciprocating member increases but also the weight of the member related thereto increases.

On the other hand, although the Young's modulus E may be increased, the Young's modulus E is a value peculiar to the substance involved in the interatomic bonding force. For this reason, it is difficult to substantially change the Young's modulus E by conventional alloying, heat treatment, etc. as long as it is a conventional steel material. Therefore, conventionally, it was also difficult to increase the bending rigidity EI from the viewpoint of the material.
Therefore, we have newly developed a material with a high Young's modulus that has never existed before,
The material is used for the piston pin to suppress the amount of deformation.
It is desired to reduce. Incidentally, JP-A-9-24287
No. 2, etc., mentions a lightweight, high-rigidity ceramic piston
There is a description about pins. However, the ceramic piston pin is not as practical as an engine member requiring reliability because it is inferior to the metal piston pin in terms of workability, fracture toughness, heat transferability and the like.

(B) Connecting Rod The connecting rod is a member that connects the piston (piston pin) and the crank shaft (crank pin), and the explosive force received by the piston
By transmitting to the shaft, reciprocating motion is converted into rotary motion. The connecting rod also reciprocates at high speed according to the engine speed. Connecting ·
As deformation of the rod, expansion and contraction due to compressive force and tensile force such as explosive force and inertial force can be considered. It is also conceivable that those forces act on the connecting rod in a tilted state, resulting in a bending moment and bending.
Furthermore, since the rod portion has a relatively long length, it is sometimes necessary to consider the stability of deformation, that is, buckling (deformation).

Here, the expansion and contraction due to compression and tension is the rigidity E
It is inversely proportional to A (E: Young's modulus, A: cross-sectional area), and bending due to a bending moment is inversely proportional to bending rigidity EI. Further, as for the buckling, the larger the bending rigidity EI, the more the buckling load increases, and the buckling becomes stable with respect to the buckling and the buckling deformation is less likely to occur. Further, if the rigidity EA and the bending rigidity EI are increased, the deformation of the connecting rod can be suppressed / reduced. However, similar to the piston pin described above, if they are increased from the aspect of shape, the weight of the connecting rod increases. Is not preferred. Therefore, it is desirable to increase their rigidity in terms of materials. In other words, it is desired to newly develop a material having a high Young's modulus that has never existed before and use the material for the connecting rod to suppress or reduce the amount of deformation.

(C) Rocker Arm The rocker arm is a reciprocating member that reciprocates at high speed in accordance with the engine speed with the valve. Then, the rocker arm transmits the movement (profile) of the cam to the valve (valve stem end) to open and close the valve. In this valve, the movement amount (lift amount) h is controlled in μm units with respect to the rotation angle θ of the cam shaft. Then, since the motion (movement amount, moving speed, acceleration, etc.) directly affects the engine performance, very accurate motion is required. If the amount of flexure of the rocker arm increases and the valve lift amount control becomes inaccurate, the performance of the engine may be degraded. Further, valve jump or bouncing may occur, which may lead to deterioration of valve durability. Therefore, the rocker arm is required to transmit accurate movement to the valve,
The amount of arm deformation is severely limited. Whether the rocker arm is a seesaw type or a swing arm type, since a bending moment mainly acts, it is necessary to increase the bending rigidity EI and reduce the amount of bending.

However, if the bending rigidity EI is increased from the viewpoint of the shape, the weight of the rocker arm increases as described above, and a larger inertial force acts on the rocker arm, which is not preferable. Therefore, it is desirable to increase their flexural rigidity EI from the material standpoint. That is, it is desired to newly develop a material having a high Young's modulus which has never been obtained, and use the material for a rocker arm to increase the bending rigidity EI and reduce the amount of deformation thereof.

Although the bending rigidity EI has been mainly described here, when the Young's modulus E is increased, the lateral elastic modulus G (G = E) is obtained.
/ 2 (1 + ν), ν: Poisson's ratio) is increased, and the torsional rigidity GI _P (G: lateral elastic modulus, I _P : sectional second polar moment) is also increased. Therefore, even when a torsion moment is further applied to the reciprocating member, the amount of deformation (twist angle ψ) can be reduced without increasing the weight of the reciprocating member.

(3) Strength In addition to the rigidity (Young's modulus E) described above, the strength of the reciprocating member may be a problem. The stress (maximum value) acting on the reciprocating member is usually determined only by the shape, regardless of Young's modulus, etc. However, if an attempt is made to reduce the acting stress by changing the shape, the reciprocating member becomes larger and the inertial mass It is not preferable because it causes an increase. Therefore, it may be desired to increase the allowable stress (proof stress) from the viewpoint of the material. In other words, in addition to being lightweight and having a high Young's modulus, a material with a large proof stress, that is, a material with a large specific Young's modulus and specific strength was newly developed and used as the reciprocating member to further expand the degree of freedom in designing the reciprocating member. It is desired to let

Therefore, the inventor of the present invention can develop a new optimum material for the reciprocating member, especially a highly rigid material, to expand the design freedom of the reciprocating member and improve the performance of the reciprocating member. I thought that it was indispensable for achieving light weight and compactness. Then, it was considered suitable to use an iron-based material having the largest Young's modulus E as a base material among general metal materials, and further investigation and research and development were conducted.

Prior to this research and development, the present inventor investigated a high-rigidity material based on an iron-based material, and found several applications. For example, Japanese Patent Laid-Open No. 5-23
The disclosure related to Japanese Patent No. 9504, Japanese Patent Application Laid-Open No. 7-188874, etc. has been made. The former publication discloses an iron-based composite material in which reinforcing particles such as carbides and nitrides are dispersed in an iron-based matrix to achieve a high Young's modulus. However, since the iron-based composite material uses reinforcing particles (Ti (C, N) etc.) lacking thermodynamic stability, a sufficiently high Young's modulus has not been obtained. Also, although there is a description of Charpy impact value, there is no description of density, strength, etc.
It is unknown whether the material is a practical material for a reciprocating member. The latter publication discloses an iron-based composite material that has a high Young's modulus using titanium diboride (TiB2), which has excellent thermal stability, as reinforcing particles. However, the publication only mentions Young's modulus and does not mention density, strength or the like. The inventors further investigated the material described in this publication and found that when a soft ferrite phase was used as a matrix, the yield strength was not sufficient, and even if the Young's modulus was high within the elastic limit, a high load was applied. It was found that the reciprocating member that receives it may undergo plastic deformation.

The present invention has been made in view of such circumstances. That is, by using an iron-based composite material having high rigidity (high Young's modulus) that is optimal as the reciprocating member (or reciprocating member), the degree of freedom in designing the reciprocating member can be increased.
An object of the present invention is to provide a reciprocating member capable of reducing the weight and size of the reciprocating device and improving its performance.

[0023]

Therefore, the present inventor has diligently studied to solve this problem, and as a result of repeating various systematic experiments, a new highly rigid iron-based composite material optimal for a reciprocating member has been newly developed. Developed and discovered. Using this iron-based composite material, a reciprocating member has been developed which can expand the design freedom of the reciprocating member, reduce the weight and size of the reciprocating device, and improve the performance.

[0024] That is, the reciprocating member of the present invention, iron matrix <br/> scan phase containing copper (Cu) of 1 to 5 wt% as a main component, 4A group (titanium group) elements Hou of 10 to 10 when the total volume of the strengthening phase mainly containing a compound is 100% by volume.
50% by volume is dispersed , Young's modulus (longitudinal elastic modulus) E is 230 GPa or more, and density ρ is 7.5 (10 ³ × Kg /
It is characterized by having a high-rigidity part made of an iron-based composite material having m ³ ) or less.

The reciprocating member of the present invention has a density ρ of 7.5.
While having a low density of (10 ³ × Kg / m ³ ) or less,
Since the high-rigidity portion having a high Young's modulus of 230 GPa or more is provided, the degree of freedom in designing the reciprocating member is remarkably increased, and the reciprocating device using the reciprocating member can be made lighter and more compact, and its performance can be improved. It's significantly easier. For example, since the high-rigidity portion has a high Young's modulus, the deformation of the reciprocating member can be reduced without increasing the weight and the size of the reciprocating member, and the motion accuracy of the reciprocating member can be improved. Moreover, since the high-rigidity part has a low density,
Since the inertial mass of the reciprocating member can be reduced, and the reduction of the inertial mass leads to a reduction in inertial force, the reciprocating member can be made even lighter and more compact.

Here, the Young's modulus refers to the longitudinal elastic coefficient, and if it is less than 230 GPa, it is not sufficient to increase the rigidity of the reciprocating device from the material surface, and the degree of freedom in designing the reciprocating member is limited. It is not preferable because Further, when the Young's modulus of the iron-based composite material is 250 GPa or more, it is more suitable for reducing the weight of the reciprocating member. As a result, the Young's modulus of the iron-based composite material increased by about 20% or more with respect to the Young's modulus of ordinary steel. Moreover, the reciprocating member according to the present invention can be manufactured by using a general iron-based member manufacturing method, conditions and the like for this iron-based composite material. Therefore, a reciprocating member having an excellent balance between Young's modulus and manufacturability can be obtained, which is very preferable. Particularly, Young's modulus of 280 GPa or more is more preferable. As a result, the Young's modulus of the iron-based composite material increased by about 40% or more with respect to the Young's modulus of ordinary steel. Moreover, the reciprocating member according to the present invention can be manufactured by using a manufacturing method that is not largely different from that of a general iron-based member for this iron-based composite material and slightly changing the manufacturing conditions, manufacturing equipment, and the like.
Therefore, a reciprocating member having an excellent balance between Young's modulus and manufacturability and having more emphasis on performance and the like can be obtained, which is particularly preferable.

Further, the density ρ is 7.5 (10 ³ × Kg /
m ³ ), the difference between the inertial mass of the reciprocating member and the inertial force acting on the reciprocating member substantially disappears, and the reciprocating member and the reciprocating device cannot be sufficiently reduced in weight and size, Further, the degree of freedom in designing the reciprocating member is limited, which is not preferable.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to embodiments of a reciprocating member and a reciprocating device. (Iron-based composite material) (1) Reinforcing phase The high-rigidity portion of the reciprocating member of the present invention comprises a matrix phase containing iron as a main component and a reinforcing phase containing a boride of a 4A group (titanium group) element as a main component. It is composed of an iron-based composite material in which is dispersed. As a result, high Young's modulus, low density, and high strength are obtained. The boride of the 4A group element, which is the main component of the strengthening phase, has a crystal structure in which the 4A group element and boron are regularly arranged, and the constituent atoms are firmly bonded by a covalent bond. The Young's modulus of the boride becomes very large due to the influence of the strong bonding force of the constituent atoms. Moreover, since the boride of the 4A group element is extremely thermodynamically stable in the iron alloy, it reacts with the constituent elements of the matrix phase, such as the invasion and substitution of different elements or the formation of other complex compounds, It produces few crystallographic and metallurgical changes.

Therefore, it is considered that an iron-based composite material having a very high Young's modulus was obtained without using a special manufacturing method, and the rigidity of the reciprocating member could be increased from the viewpoint of the material.
Further, the high-rigidity portion of the reciprocating member of the present invention has a total of 1
It is preferable that when it is set to 00% by volume, it is composed of 10 to 50% by volume of a strengthening phase and 60% by volume or less of a non-matrix phase phase with respect to this strengthening phase. The non-matrix phase (matrix phase,
By setting the content (other than the strengthening phase) to a certain ratio or less, an iron-based composite material having a higher Young's modulus can be obtained without lowering the toughness and ductility of the iron-based composite material. Further, since the high-rigidity portion is made of the iron-based composite material having excellent toughness, ductility, and Young's modulus, the degree of freedom in designing the reciprocating member can be further expanded.

The non-matrix phase is specifically a boride other than a boride of a Group 4A element (eg (Fe, C
r) ₂ B) or an intermetallic compound containing a Group 4A element (for example,
(Fe, Cr) ₂ Ti or other Laves phase). Here, if the reinforcing phase is less than 10% by volume, the effect of increasing the rigidity cannot be obtained, and if it exceeds 50% by volume, the boride aggregates or coalesces to reduce the mechanical properties of the iron-based composite material. It is not preferable. The strengthening phase is 100% by volume
When the reinforcing phase is 20 to 35% by volume, the obtained Young's modulus and mechanical properties are well-balanced, and practical manufacturability that can be accommodated by existing equipment is obtained, which is more preferable. In addition, the non-matrix phase is 60 times stronger than the strengthening phase.
When the content exceeds the volume%, the strengthening phase containing a boride of a Group 4A element as a main component in the iron-based composite material decreases relatively, the Young's modulus of the iron-based composite material decreases, and the matrix phase hardens or Embrittlement is not preferable.

On the other hand, when the non-matrix phase is 40% by volume or less with respect to the strengthening phase, the hot workability is greatly improved,
More preferable. As the boride of the 4A group element that is the main component of the strengthening phase, one or more boride of the 4A group element, titanium (Ti), zirconium (Zr), or hafnium (Hf), is used. If the Young's modulus of the boride as a simple substance is at least 250 GPa or more, an iron-based composite material having a sufficiently high Young's modulus can be obtained by dispersing the reinforcing phase. Four
Among the borides of Group A elements, titanium diboride (Ti
B ₂ ) is suitable as the main component of the reinforcing phase because it has a high Young's modulus and excellent thermal stability. That is, when the strengthening phase contains titanium diboride (TiB ₂ ) as the main component, and the non-matrix phase contains boride and / or titanium compound other than this titanium diboride (TiB ₂ ) as the main component, It is suitable. Furthermore, the particle size of the boride of the Group 4A element mainly constituting the strengthening phase is 100 μm or less, and more preferably 2
It is suitable that it is 0 μm or less. With a high Young's modulus,
This is because an iron-based composite material having excellent toughness and ductility can be obtained.

(2) Matrix phase In the iron-based composite material constituting the reciprocating member of the present invention, the matrix phase containing iron as the main component contains the reinforcing phase containing the boride of Group 4A (titanium group) element as the main component. It is dispersed. This matrix phase uses pure iron or iron alloy as a matrix (base material). Ferrous alloys for iron alloys,
There are austenite type and martensite type.

The matrix phase has a carbon (C) content of 0.
It is preferably 5% by weight or less. 0.5% by weight of C
In the following case, the thermodynamic stability of the boride of Group 4A element dispersed in the matrix phase can be further maintained. That is, even in a high temperature range, the group 4A element of boride and C
The formation of carbides and carbon borides from these is suppressed, and the effect of increasing the Young's modulus by the boride of the 4A group element can be maximized, which is preferable. vice versa,
If it exceeds 0.5% by weight, the amount of carbides and carbon borides increases, and the high rigidity portion becomes brittle, which is not preferable. Further, it is more preferable that the content of C is 0.2% by weight or less, and further C
It is even more preferable that it is substantially free of. The reason why “substantially” is not included is that it may be included as an unavoidable impurity to some extent.

Further, the matrix phase contains one or more kinds of vanadium (V) and chromium (Cr) when the total amount of the matrix phase is 100% by weight.
It is suitable to contain 5.0% by weight or less. When these elements are included, B having a higher Young's modulus in the matrix phase is obtained.
Ferrite having a CC structure is stabilized, an iron-based composite material having a higher Young's modulus can be obtained, and high rigidity of the reciprocating member can be promoted, which is preferable. However, if the content of these elements exceeds 25.0% by weight, a brittle compound with iron (sigma phase) precipitates and embrittles the matrix phase, which is not preferable.

Further, since the matrix phase contains V and Cr, the surface treatment property such as nitriding treatment (eg, tufftride) is improved. Therefore, by subjecting the high-rigidity portion to the surface treatment, the wear resistance of the high-rigidity portion can be improved, and fretting wear or the like can be suppressed or prevented. Also, various coatings (TiN, etc.) may be applied. When the total matrix phase is 100% by weight, V
0.1 to 3 wt% and / or Cr 0.5 to 20
It is more preferable that the content is wt%. Further, it is more preferable to contain 0.1 to 3% by weight of V and / or 0.5 to 4% by weight of Cr. In particular, it is particularly preferable to contain 0.1 to 3% by weight of V and 0.5 to 8% by weight of Cr at the same time.

Generation of the σ phase and the compound phase of vanadium and iron is suppressed, and cracking and embrittlement during hot working can be suppressed or prevented. Further, the surface hardness can be secured by an inexpensive nitriding treatment or the like, and the wear resistance can be improved. The nitriding treatment includes tuftride and the like. By improving the surface hardness by nitriding or the like, fretting wear of the rotary shaft member can be prevented.

The matrix phase contains nickel (N) when the total amount of the matrix phase is 100% by weight.
i), one or more of cobalt (Co), the total of which is 2
It is suitable to contain 5.0% by weight or less. The inclusion of these elements is preferable because austenite with an FCC structure can be obtained in the matrix phase, and toughness can be improved as compared with the matrix phase containing only ferrite. However, if those elements exceed 25.0% by weight, a matrix phase mainly composed of austenite and a Young's modulus lower than that of the matrix phase mainly composed of ferrite are not preferable.
It is more preferable that the total amount be 15% by weight or less, because the toughness can be increased without significantly reducing the Young's modulus.

The matrix phase contains 0.2 to 1 of copper (Cu) when the entire matrix phase is 100% by weight.
It is suitable to contain 0.0% by weight or less. When the matrix phase contains Cu, the strength of the matrix phase is improved, which is preferable. In particular, if Cu is ultrafinely matched and precipitated, the strength is further improved. However, if Cu is less than 0.2% by weight, C
It is not preferable because the amount of precipitation of u is small and a sufficient improvement in strength cannot be expected. On the other hand, when the Cu content exceeds 10.0% by weight, the Young's modulus of the matrix phase is lowered, and liquid phase cracking is likely to occur during hot working, which is not preferable. Here, if the content of Cu is 5% by weight or less, it is more preferable that the Young's modulus is suppressed from being lowered and the strength is significantly improved.

Further, if the Cu content is 1 to 5% by weight, both improvement of strength and suppression of decrease in Young's modulus can be achieved at the same time, which is more preferable. The matrix phase containing Cu includes both a solid solution state of Cu and a precipitation state of ε-Cu phase.

The matrix phase contains one or more elements of molybdenum (Mo), niobium (Nb), tantalum (Ta), tungsten (W), and hafnium (Hf) when the entire matrix phase is 100% by weight. It is preferable that the total content is 10.0 wt% or less. These elements improve the strength of the matrix phase by forming a solid solution and precipitation in the matrix phase, and the inclusion of these elements in the matrix phase improves the strength of the high rigidity portion of the reciprocating member. It is preferable because it can be achieved. However, if the amount of these elements exceeds 10.0% by weight, a large amount of precipitates are generated, the ferrite phase is hardened, and the matrix phase is embrittled, which is not preferable. It is more preferable that the total amount be 5% by weight or less, because the generated precipitates have an appropriate amount and become fine, and the strength can be increased without embrittlement of the matrix phase.

As described above, the matrix phase can be composed of a wide variety of compositions. For example, the matrix phase having the following composition is particularly suitable as the reciprocating member. That is, when the matrix phase is 100% by weight of the whole matrix phase,
0.5% by weight or less of carbon (C) and 0.2 to 10% by weight
Copper (Cu), molybdenum (Mo) and niobium (Nb)
25 weights in total from the metal group consisting of vanadium (V) and chromium (Cr), and one or more metal elements of 10 weight% or less in total from the metal group consisting of tungsten, tungsten (W) and tantalum (Ta) It is preferable to contain at least one element selected from the element group consisting of 1 or more kinds of metal elements of 1% or less.

When the matrix phase is 100% by weight, the matrix phase is 1 to 5% by weight of copper (Cu), 0.1 to 3% by weight of vanadium (V) and / or 0.1% by weight. It is preferable that it contains 5 to 4% by weight of chromium (Cr) and contains substantially no carbon or contains 0.5% by weight or less.

(Reciprocating member) (1) Specific Young's modulus E / ρ The high rigidity portion of the reciprocating member of the present invention has a Young's modulus of E (G
Pa) and the density is ρ (10 ³ × Kg / m ³ ), the specific Young's modulus E / ρ is 30 (× 10 ⁻³ GPa · m ³ / Kg)
The above is preferable. As described above, when the density is low and the Young's modulus is high, the inertial force acting can be reduced by reducing the inertial mass, and the deformation amount of the reciprocating member can be reduced. Here, a high specific Young's modulus E / ρ in which the Young's modulus E and the density ρ are related is preferable in the following point.

The reciprocating member has its own inertial mass m.
Receives an inertial force F proportional to. Assuming that the amount of deformation δ due to the inertial force F of the self and its bending rigidity EI, the amount of deformation δ is F
It is proportional to / EI, and further to m / EI. If the volume of the reciprocating member is V, δ is ρV / EI = (ρ / E) · (V
/ I). After all, in order to reduce the deformation amount δ due to the inertial force of the reciprocating member itself, it is sufficient to increase I / V from the shape surface and E / ρ from the material surface. Therefore, if the specific Young's modulus E / ρ is high, it is possible to reduce the amount of deformation δ of the reciprocating member while reducing the weight and size of the reciprocating member, which is very preferable.

In addition, among the reciprocating members, there are many members that reciprocate at high speed, and in the case of such reciprocating members, the natural frequency of them may be a problem. For example, in the case of an engine, the above-mentioned rocker arm, valve, valve spring, and other valve operating system members. In particular,
Valves and springs need to prevent surging at high speed. When surging occurs, valve jumps, valve bounces, etc. may occur, which may lead to valve timing irregularities and valve spring breakage. Therefore, normally, the natural frequency of such a valve train is
It is desirable to set it to a high value with a sufficient margin above the maximum engine speed.

Generally, the natural frequency of a member is determined by the material and the shape, but it is known from the material standpoint that it is proportional to the square root (E / ρ) ^1/2 of the specific Young's modulus E / ρ. .
However, as can be seen from FIG. 1, it is difficult to adjust and improve the natural frequency of the reciprocating member from the material surface, because the specific Young's modulus E / ρ could hardly be changed with the conventional material. there were. However, since the reciprocating member of the present invention is provided with the high-rigidity portion having a high specific Young's modulus E / ρ, the natural frequency thereof can be easily adjusted and improved from the material side, and the reciprocating member having a greater degree of design freedom can be obtained. An exercise member can be provided, which is particularly preferable. The specific Young's modulus E / ρ of the high rigidity portion of the present invention is 38 (× 10 ⁻³ GPa · m ³ / K).
When it is g) or more, the degree of freedom in designing the reciprocating member is further expanded, which is preferable.

(2) Proof Strength The high-rigidity portion of the reciprocating member of the present invention preferably has a proof stress (0.2% proof stress) of 510 MPa or more. Since the reciprocating member of the present invention has a high Young's modulus and a low density as described above, it is possible to expand the degree of freedom in design as never before. In addition to this, if the proof stress is high, the degree of freedom in designing the reciprocating member is further expanded, and the reciprocating member and the reciprocating device can be made lighter and more compact, and the performance of the reciprocating device can be further improved. Here, the proof stress refers to 0.2% proof stress, which is “stress at which permanent set becomes 0.2%”. If it is less than 510 MPa, the degree of freedom in designing the reciprocating member is limited in terms of strength, which is not preferable. On the contrary, when the proof stress is 600 MPa or more, the degree of freedom in designing the reciprocating member is further expanded, which is more preferable.

(3) Reciprocating member The reciprocating member of the present invention is preferably a piston pin at least a part of which is a high-rigidity portion. As mentioned above, the piston pin is a member that connects the piston and the small end of the connecting rod.
A very large explosive force acts on the piston, and further,
A large inertial force acts on the piston. Particularly, in recent engines, since the explosion pressure is increased and the rotation speed is increased due to the improvement of combustion efficiency, the force acting on the piston is further increased. However, the large force acting on the piston is normally transmitted from the piston pin to the small end of the connecting rod in the state shown in FIG. Therefore, a very large bending moment acts on the piston pin. If the amount of bending due to this bending moment increases, a large secondary stress may be generated in the pin boss portion of the piston or the like. Further, the slidability between the inner peripheral surface of the pin hole of the piston and the outer peripheral surface of the piston / pin may deteriorate, which may cause premature wear or scuffing.

However, if the piston pin is provided with the high-rigidity portion of the present invention, the flexure amount δ of the piston pin can be remarkably reduced, and the generation of secondary stress between the piston and the piston pin can be suppressed or reduced. The slidability can be improved. Moreover,
Since the high-rigidity portion has a low density, the weight of the piston pin can be reduced, and the inertial mass of the piston pin itself and the piston can be reduced. As a result, the weight of the reciprocating device can be further reduced. in this way,
The piston pin is one of the best embodiments as the reciprocating member of the present invention.

Further, as described above, the high rigidity portion of the present invention comprises a matrix phase containing iron as a main component and a reinforcing phase containing a boride of Group 4A (titanium group) element as a main component. Not only rigidity and low density, but also excellent strength and toughness.
Further, unlike the ceramic piston pin, the piston pin provided with the high-rigidity portion of the present invention has good productivity and can be easily mass-produced. Therefore, also from this point of view, it is preferable that the piston pin, which is required to have improved strength, reliability, and productivity, is provided with the high-rigidity portion of the present invention.

Other Specific Reciprocating Member As one embodiment of the reciprocating member of the present invention, a piston
Although a pin is illustrated, the present invention is applicable to a wide variety of reciprocating members. For example, if it is an engine system, rocker arm, valve, retainer (upper spring seat), cotter (split collet), valve spring, valve lifter, shim, piston (including rotor for rotary engine), There are reciprocating members such as piston pin, piston ring, connecting rod, push rod (OHV, engine, etc.), oil regulator relief valve (pressure adjusting piston), etc. In addition, reciprocating members such as compressor pistons (for automobile air conditioners), fuel injection pump plungers (diesel engines, etc.), fuel injection nozzle needle valves (diesel engines, etc.), suspension inner cylinders, etc. There is.

Furthermore, planing machines for machine tools, looms (particularly, heddle and reed parts), sewing machines (particularly needles and table parts), air conditioning compressors (particularly piston parts) for automobiles, printers (particularly, There is a reciprocating member such as a head portion). In any case, the present invention can be applied to any reciprocating member for which high rigidity and lightweight improvement are desired.

(4) Iron-based composite material manufacturing method The iron-based composite material forming the high-rigidity portion of the reciprocating member of the present invention is preferably manufactured as follows. That is, in the method for manufacturing an iron-based composite material, a raw material powder is selected from a boride powder of a 4A group element, a 4A group element powder, and a boron powder, and the compounding ratio of the 4A group element and boron is 0.45 in atomic ratio. A raw material powder mixing step of mixing a strengthening phase raw material powder adjusted to be 0.80 and a matrix phase raw material powder containing iron as a main component, and a compact compact from the raw material powder mixed in this raw material powder mixing step It is preferable that the method includes a consolidation molding step for obtaining the above and a sintering step for sintering the molded body obtained by this molding step to obtain a sintered body.

The strengthening phase may be formed by a boride powder of a Group 4A element contained in advance in the strengthening phase raw material powder,
The mixed 4A group element powder and the boron raw material powder may react with each other in the sintering step, and may be formed by a boride of the 4A group element generated therein. By adjusting the compounding ratio of the 4A group element and boron to an atomic ratio of 0.45 to 0.80, formation of a non-matrix phase composed of iron boride or an intermetallic compound of the 4A group element is suppressed, and iron It is easy to achieve a high Young's modulus of the base composite material. A commercially available powder can be used as the reinforcing phase raw material powder, but the boride powder of the 4A group element is preferably a powder having an average particle size of several μm or less. When the particle size is large, it may be crushed by a device such as a ball mill, a vibration mill, or an attritor.

The matrix phase raw material powder is powder of pure iron or iron alloy, and commercially available powder can be used. For example, pure iron powder, stainless powder, or the like produced by the atomizing method can be used. The average particle size of the matrix phase raw material powder is more preferably 180 μm or less, further preferably 45 μm or less. When the average particle size is 45 μm or less, densification of the sintered body is further promoted.

The raw material powder mixing step is a step of uniformly mixing the matrix phase raw material powder and the reinforcing phase raw material powder, but it is not necessary to perform a special mixing method or pretreatment, and a normal powder mixing apparatus is used. it can. For example, a powder mill such as a V type or a double cone type, a ball mill, or a vibration mill may be used. When a boride powder of a Group 4A element is used as the strengthening phase raw material powder and the powder forms secondary particles or the like, it is pulverized using a high energy mill such as an attritor in an inert gas atmosphere. Good to do.

In the consolidation forming step, for example, die forming, C
IP molding or the like can be used. In addition, the molding pressure is 2
When the pressure is 00 MPa or more, the compacted body and the sintered body thereof are sufficiently densified, which is preferable.

The sintering step is preferably performed in vacuum or in an atmosphere of inert gas or reducing gas. This is because the oxidation of iron in the matrix phase can be prevented or suppressed. The sintering step is preferably performed at a heating temperature of 1100 to 1300 ° C. If the temperature is lower than 1100 ° C, a sintered body having a sufficient density cannot be obtained, and if the temperature is higher than 1300 ° C, a large amount of liquid phase is generated depending on the type of boride formed, and the shape of the sintered body may not be maintained. Is. The heating time is
It is preferably 0.5 to 4 hours. This is because if the time is less than 0.5 hours, the density of the sintered body is not sufficiently improved, and if the time exceeds 4 hours, the energy efficiency is not good.

Further, the method for producing an iron-based composite material comprises: a matrix phase raw material containing iron as a main component; and a strengthening phase raw material having an atomic ratio of the group 4A element and boron of 0.45 to 0.80. It is preferable to have a melting step of melting the molten steel and a casting step of pouring the raw material melted by the melting step into a mold to form an ingot. For the strengthening phase raw material, for example,
Examples include ferro titanium, ferro zirconium, and ferro boron.

For the melting step, for example, a high frequency induction vacuum melting furnace using a ceramic crucible, an argon arc melting furnace, a plasma melting furnace, a high frequency induction vacuum melting furnace using a water-cooled copper crucible, or a high frequency induction floating melting furnace is used. Melt equipment can be used.

Furthermore, if a hot working step of hot working the sintered body or ingot is performed after the above-mentioned sintering step or casting step, it is possible to densify them to a substantially true density, which is preferable. Is. For example, in the case of a steel ingot, the porosity generated inside by this hot working can be reduced, and further, the boride (titanium diboride (TiB2), etc.) in the strengthening phase can be miniaturized. Thereby, the strength, toughness, ductility, etc. of the iron-based composite material can be improved.

As the hot working step, for example, hot forging,
There are hot rolling, hot extrusion, hot swaging, etc. In addition, this hot working is preferably performed in the range of 900 to 1200 ° C. This is because if it is lower than 900 ° C, the deformation resistance at the time of processing is large, and if it exceeds 1200 ° C, liquid phase may occur. In the case of densifying the sintered body, HIP (hot isostatic pressing) treatment may be performed after the sintering step instead of the hot working step. For example, this H
The IP treatment is preferably performed under the conditions of 900 to 1200 ° C., 500 to 2000 atmospheric pressure, and 1 to 10 hours. As described above, the iron-based composite material used in the present invention is a conventional powder metallurgy,
It can be manufactured using the melting and casting methods.
It can be manufactured using conventional equipment. Therefore, it is also a material that is easy to improve productivity and reduce cost.

[0063]

EXAMPLE The following reciprocating member will be specifically described as an example of the reciprocating member of the present invention. (Reciprocating member) (1) Piston pin, connecting rod, piston First, as the reciprocating member disposed in the cylinder of the engine, the piston pin 300, the connecting rod 400, and the piston 500 shown in FIG. explain.

Piston Pin The piston pin 300 is a hollow cylindrical member that connects the piston 500 and the small end portion 410 of the connecting rod 400, as shown in FIGS. 2 and 3. Then, through the piston pin 300, the piston 50
The explosive force and inertial force acting on 0 are transmitted to the connecting rod 400. As described above, a large bending moment acts on the piston pin 300 due to the combustion pressure and inertial force received by the piston 500. However, when the piston pin 300 is made of the high rigidity portion of the present invention, the deformation can be reduced. Therefore, it is preferable. Also, the piston pin 30
0 can be made lighter, and its own inertial force can be reduced.
preferable.

Furthermore, if the high-rigidity portion of the present invention is excellent in strength, toughness, fatigue resistance, etc., the life and reliability of the piston pin 300 that is subjected to repeated stress will increase, which is more preferable. For example, since the high rigidity portion of the present invention has a fatigue strength of 450 to 750 MPa, it can be sufficiently used as the piston pin 300. In addition, in order to improve slidability, wear resistance, etc. between the pin hole 511 of the piston 500 and the outer peripheral portion 310 of the piston pin 300, the surface of the outer peripheral portion 310 may be polished or lapped. Also, piston pin 3
00 is the small end 410 of the connecting rod 400.
Pressed into to make it a semi-floating type (semi-flow type). This is because it has a small number of parts and is superior in terms of cost and noise. Of course, the floating type or the fixed type may be used.

The piston pin 300 has a hollow cylindrical shape in order to reduce the weight, but the central portion 32 of the inner peripheral portion 320 thereof.
2 was the wall thickness. This is because deformation is suppressed by attaching the small end portion 410 and the bending moment is maximized in the central portion.
On the contrary, the inner peripheral portion 3 at both ends, which has a relatively small bending moment
20 is a tapered inner surface 321.

As shown in FIGS. 2 and 4, the connecting rod 400 includes an annular small end portion 410, an I-shaped cross-section rod portion 420, an annular large end portion 430, and a cap bolt 45.
0 and nut 460. The connecting rod 400 transmits the explosive force acting on the piston 500 to the crank pin 230 of the crank shaft 200, and the reciprocating motion of the piston 500 is transmitted to the crank shaft 2.
It is converted into a rotary motion of 00.

The piston 500 is connected to the small end portion 410 via the piston pin 300, and the small end portion 410
Is connected to a large end 430 via a rod portion 420, and the large end 430 is further connected to a crank pin 230. Since a semi-flow type is used between the small end portion 410 and the piston pin 300, a bearing (bush) is not provided on the inner peripheral surface of the small end portion 410, but it is formed on the inner peripheral surface of the large end portion 430. Provided a half insert type connecting rod bearing 431. Further, since the integrally forged crank shaft 200 is used, the large end portion 430 is of a horizontal split type in order to secure the assembling property. Then, connect them with a cap bolt 45 which is a high strength reamer bolt.
0 and nut 460.

When an assembled crank shaft is used, a so-called eyeglass-type connecting rod can be used. Further, the shape of the rod portion may be an H shape having a larger bending rigidity. Further, the shoulder 4 of the large end 430
35, an oil jet hole for cooling the piston 500 may be appropriately provided. Such a connecting rod 400 also reciprocates at high speed. And
In general, the inertial mass is larger than that of a piston or the like, and the inertial force acting on the connecting rod 400 (particularly on the small end portion 410 side) itself is also large. So, this connecting
When the rod 400 is made of the high-rigidity portion of the present invention, the inertial mass can be reduced, and not only the connecting rod 400 can be made lightweight and compact, but also the engine response can be improved.

Further, since the connecting rod 400 of the present invention having a high rigidity portion is lightweight and has high rigidity, deformation and buckling of the connecting rod 400 can be suppressed while achieving weight reduction and compactness. Therefore, a connecting rod having a great degree of freedom in design can be obtained. Furthermore, if the high-rigidity portion of the present invention is excellent in strength, toughness, fatigue resistance, etc., the life and reliability of the connecting rod 400 that is subjected to repeated stress are increased, which is more preferable. Further, when the iron-based composite material of the high rigidity portion of the present invention is excellent in forgeability, it is preferable because productivity is not lowered. For example, the iron-based composite material of the present invention has a deformation resistance of 1.1 to 1.5 times that of medium carbon steel, and good product molding can be performed with conventional forging equipment.

Piston The piston 500 reciprocates at high speed in the cylinder while maintaining airtightness, and the explosive force is applied to the crankshaft 200.
2 and 5, as shown in FIGS. 2 and 5, it is a substantially bottomed tubular member, and is composed of a pin / boss portion 510, a skirt portion 520, a ring groove portion 530, a head portion 540, and a strut 580. The pin boss portion 510 is a bearing portion for supporting the piston pin 300, and a smooth pin hole 511 is squeezed inside. The pin hole 5
The above-mentioned piston pin 300 is inserted through 11, and the piston 500 is rotatably supported.

The skirt portion 520 has a pin / boss portion 510.
It extends downward in a direction perpendicular to, and serves to suppress the swing of the piston 500 and stabilize the reciprocating motion. Here, in consideration of lightness and reduction of noise, the pin / boss 5
A slipper skirt cut out in the 10 direction. The ring groove portion 530 is a groove that is located on the entire circumference above the skirt portion 520 and is used to fit the top ring, the second ring, and the oil ring. The head portion 540 is a disc-shaped member located above the ring groove portion 530,
This is the part that compresses air (air mixture) and receives combustion pressure. A crescent-shaped valve recess is formed on the top surface to avoid interference with the valve.

The strut 580 is a reinforcing member attached (cast) to the piston 500 in order to suppress thermal deformation of the piston 500. By providing this, the piston clearance can be reduced, and the life of the piston, the quietness of the engine, and the output performance of the engine can be improved. Since such a piston 500 reciprocates at high speed, it is required to be lightweight like the piston pin 300 and the like, but it is also required that its deformation is small.

As the deformation of the piston 500, deformation due to thermal expansion and deformation due to inertial force or explosive force are mainly considered.
The former deformation can be suppressed by improving the material surface, but the deformation can also be suppressed by the reinforcing member such as the strut 580 described above. In order to suppress the latter deformation, it is possible to suppress it by improving the rigidity from the shape surface or the material surface.

It is preferable that the piston 500 is composed of the high-rigidity portion of the present invention because it is possible to reduce the weight and size of the material and reduce the deformation. In particular, when the strut 580 is made of the high-rigidity portion of the present invention, the strut 580 has high rigidity, so that the piston 500
It is especially easy to suppress the deformation of. Moreover, it is lightweight and convenient. The piston 500 may be made of a normal aluminum alloy, and only the strut 580 may be made of the high rigidity portion of the present invention. As a result, the piston 5 is lighter and has less deformation and stable piston clearance.
00 is obtained. In this case, the strut 580 corresponds to the reciprocating member of the present invention. In any case, since the strut 580 and the like are provided with the high rigidity portion of the present invention,
The degree of freedom in designing them can be further expanded.

(2) Valve Operating System Member Next, the present invention will be described in detail by taking a reciprocating member of the valve operating system as an example. The valve operating mechanism transmits the rotation of the crank shaft to the cam shaft to drive and rotate the cam shaft, so that the intake valve and the exhaust valve of each cylinder are designed at appropriate timings for ignition sequence. It is a mechanism that opens and closes according to. Figure 6
Rocker arm 710, cotter 720,
The retainer 730, the valve 750, etc. are used to introduce and seal the air-fuel mixture into the combustion chamber and to discharge the combustion gas from the combustion chamber.

Rocker Arm The rocker arm 710 transmits the movement of the cam 600 to the valve stem end 751 to open and close the valve. FIG. 6 shows a seesaw type pivotally supported by a rocker shaft 711 and swinging. Of course, one end is a cylinder
It may be a swing arm type which is supported by the head and swings. The rocker arm 710 has a sliding contact portion 712 that slidably contacts the cam surface of the cam 600 at one end, and presses the valve stem end 751 at the other end and adjust screw 713 for adjusting tappet clearance. Have. It is also possible to further reduce friction loss by providing a needle roller or the like in the sliding contact portion 712. Further, it is preferable that the end surface of the adjusting screw 713 that comes into contact with the valve stem end 751 has improved wear resistance by surface hardening treatment or the like. The substantially bow-shaped rocker arm 710 reciprocates at a high speed around a rocker shaft 711 in the substantially center. Then, in order to reduce the inertial force and improve the responsiveness, reduction of the inertial mass is required. Further, in order to ensure accurate valve timing, it is desired that its deformation is strictly limited and that it has high rigidity. Therefore, if the rocker arm 710 is made of the high rigidity portion of the present invention, these requirements can be satisfied, and the degree of freedom in designing the rocker arm 710 is further expanded, which is very preferable.

Cotter and Retainer The cotter 720 and the retainer 730 are taken out from FIG. 6, and the whole thereof is shown in FIG. The retainer 730 is a spring upper seat of the valve spring 740. The retainer 730 is a cylindrical member that bulges downward in the center, and a tapered hole for disposing the cotter 720 is provided in the center, and the retainer 730 abuts the upper end surface of the valve spring 740 at the outer peripheral portion and Part supports the valve spring 740 from the inside. The cotter 720 is a retainer that is divided into two parts, and a protrusion is provided inside the cotter 720 that engages with a groove 752 in the vicinity of the outer circumference of the valve stem end 751, and the outside of the cotter 720 is tapered. The surface is formed. The cotter 720 is disposed between the outer peripheral surface of the valve stem end 751 and the inner peripheral surface of the retainer 730, and connects the valve 750 (near the valve stem end 751) and the retainer 730. As a result, the valve 750 is biased to the closing side via the retainer 730.

These cotter 720 and retainer 730
Is a member that reciprocates at high speed, and it is required to reduce inertial mass and rigidity. Therefore, cotter 7
It is preferable that the 20 and / or the retainer 730 are made of the high-rigidity portion of the present invention because the inertial force can be reduced, the responsiveness can be improved, and the deformation can be reduced.

The valve valve opens and closes the combustion chamber, and includes an intake valve for introducing the air-fuel mixture into the combustion chamber and an exhaust valve for discharging the combustion gas from the combustion chamber. Although not limited to any one, FIG. 6 shows an intake valve. This valve 750 is a valve head 755
And a valve stem 753 and a valve stem end 751. The valve head 755 has a so-called tulip shape (a shape in which the combustion chamber side is recessed) in order to reduce the flow resistance of gas and further reduce the weight. The seat surface 756 is provided with a steride deposit to improve wear resistance. An elongated columnar valve stem 753 extends from the valve head 755 to the upper side, and the tip thereof serves as the above-mentioned valve stem end 751. The valve 750 is also a member that reciprocates at high speed, and is required to be lightweight in order to reduce inertial force and improve responsiveness. Furthermore, since the valve stem 755 is also an elongated columnar member, it is required to increase the buckling load, that is, have high rigidity. So valve 7
It is advantageous that 50 is made of the high-rigidity portion of the present invention, because the inertial mass can be reduced and the rigidity can be increased. In this valve 750, the valve head 755 and the valve stem 753 were integrally manufactured, and the whole was made into the high rigidity portion of the present invention. However, the invention is not limited to this, and one of them is manufactured as a reciprocating member having the high-rigidity portion of the present invention, the other is manufactured with another heat-resistant alloy, etc., and both are welded to form one valve. Is also good. Although the reciprocating member of the engine has been described above from the viewpoints of weight reduction and high rigidity, the following can be said. When the reciprocating member has the high-rigidity part of the present invention, the high-rigidity part is made of an iron-based composite material having a reinforced phase with high thermal stability, so that the Young's modulus does not decrease even at high temperatures and heat resistance is high. It is also excellent in sex. That is, a reciprocating member having good high temperature characteristics can be obtained.

(Piston Pin) A hollow cylindrical piston pin shown below is manufactured using the iron-based composite material of the present invention (first to third embodiments) and a conventional steel material (comparative example). The Young's modulus and the like were measured. (1) Production First Example Stainless steel powder (SUS430: # 330), titanium boride powder (average particle size 4 μm), ferrotitanium powder (# 330), ferroboron powder (# 250) are shown in Table 1.
The ingredients were blended in a weight ratio shown in 1 and mixed uniformly (raw material powder mixing step). In the present example, it was intended to form an iron-based composite material by dispersing 20% by volume (based on 100% by volume) of the titanium boride particles as a main component in the Fe-Cr alloy matrix phase. After the raw material powder mixing step, the uniformly mixed raw material powder is used to perform cold isostatic pressing (343 MPa) to obtain a diameter of 70 mm and a height of 210.
A consolidation molded body of mm was obtained (consolidation molding process). The compacted body was degassed (0.13 P
About a)

The enclosed body was heated in an electric furnace for sintering (1150 ° C. × 2 hours), and then immediately extruded at a high temperature to obtain a sintered body (sintering step). This sintered body was hot extruded by a hydraulic horizontal 400t press to form an extruded material having a diameter of 25 mm x 1000 mm (hot working step). Further, this extruded material was subjected to machining such as cutting, grinding and polishing to obtain a piston pin having an outer diameter of 21 mm and a length of 47.5 mm. As shown in Table 2, the inner diameter of the piston was the same in the first to third examples and the comparative example, and in the fourth to sixth examples, the bending rigidity thereof was adjusted to be substantially equal.

Second Example An iron-based composite material was formed by dispersing 30% by volume (100% by volume in total) of a reinforcing phase containing titanium boride particles as a main component in an Fe-Cr alloy matrix phase. Except as intended, it is basically the same as the first embodiment.

Third Example An iron-based composite material was formed by dispersing 46% by volume (total 100% by volume) of a strengthening phase containing titanium boride particles as a main component in an Fe-Cr alloy matrix phase. Except as intended, it is basically the same as the first embodiment.

Fourth Embodiment As shown in Table 2 with respect to the first embodiment, this is a piston pin in which only the inner diameter is changed.

Fifth Embodiment As shown in Table 2 in comparison with the second embodiment, this is a piston pin in which only the inner diameter is changed.

Sixth Embodiment As shown in Table 2 with respect to the third embodiment, this is a piston pin in which only the inner diameter is changed.

Comparative Example A commercially available high-strength structural steel material (SNCM420: carburized and hardened material) was used as a raw material and machined in the same manner as in the above-mentioned Examples to obtain piston pins having inner diameters shown in Table 2. After machining, heat treatment (carburizing quenching / tempering) is performed to obtain a surface Vickers hardness of 800 HV and a hardening depth of 0.4 m.
m.

[0089]

[Table 1]

[0090]

[Table 2]

(2) Measurement of material properties Measurement results of Young's modulus, density, proof stress and elongation of the extruded materials produced in the first to sixth examples and the high strength structural steel (SNCM420) used in the comparative example Are also shown in Table 2. Table 2 also shows the specific Young's modulus obtained from these and the weight reduction rate based on the comparative example. The Young's modulus, density, proof stress, and elongation of each example were determined as follows.

(A) Young's modulus Young's modulus was measured by the composite oscillator method. The composite oscillator method is to manufacture a composite oscillator in which a crystal oscillator is bonded to a test piece (high rigidity portion of the first to fourth examples and the comparative example), and the resonance between the composite oscillator and the crystal oscillator is produced. This method evaluates Young's modulus by obtaining the natural frequency of the test piece from the difference in frequency.

(B) Proof strength 0.2% yield strength was determined from the load-elongation diagram measured using an Instron tester. The Instron tester is a universal tensile tester manufactured by Instron (manufacturer name), and the drive system is electric motor control.

(C) Density The density was determined by the water immersion method (Archimedes method) in which the volume is calculated from the difference between the dry weight and the weight in water to calculate the density.

(D) Elongation Here, "elongation" means elongation at break, and elongation at break = (L _f using the gauge length L _f at break and the gauge length L ₀ before test. It is represented by −L ₀ ) / L ₀ × 100 (%). Here, the test piece was marked in advance to determine the reference points, the distance between the reference points was measured before and after the test, and L ₀ and L _f were obtained.

(3) radial crushing test A radial crushing test was carried out on each of the above-mentioned examples and comparative examples to measure the relationship between bending load and strain. FIG. 10 shows the measurement results of the first to third examples and the comparative example, and FIG. 11 shows the measurement results of the fourth to sixth examples and the comparative example. The radial crush test is shown in FIG.
As shown in (1), compression was performed from above and below each piston pin through a pressure plate with a hydraulic 10t universal testing machine. The bending load at this time was measured by the load cell of the tester, and the strain was measured by the strain gauge attached to the inner peripheral surface of each piston pin.

(4) Evaluation Young's Modulus and Specific Young's Modulus As can be seen from Table 2, the Young's modulus of the example of the present invention is about 10 to 65% higher than that of the comparative example. Then, the strengthening phase is titanium diboride (TiB2) with a low density.
Therefore, the overall density is reduced by about 10 to 20% depending on the volume ratio of titanium diboride (TiB2). As a result, when compared with the specific Young's modulus E / ρ, the specific Young's modulus E / ρ is about 1.4 to 2.0 in the example.
It has doubled and improved.

As can be seen from the deformation tables 1 and 2, the Young's modulus becomes higher as the ratio of the strengthening phase increases. As can be seen from FIG. 10, in the case of the same shape, the piston pin provided with the high-rigidity portion of the present invention greatly reduces its deflection (distortion),
It can be seen from the material side that the bending rigidity of the piston / pin could be improved. Moreover, as is clear from Table 1, the bending rigidity was improved and at the same time the weight was reduced. From this, the degree of freedom in designing the reciprocating member can be remarkably expanded, and the reciprocating device can be further improved in performance and reduced in weight and size.

Further, as can be seen from FIG. 11, if the bending rigidity is the same as the conventional one, the piston pin having the high rigidity portion of the present invention is remarkably lightweight (about 35% weight reduction).
Has been achieved. Further, since the inertial force can be reduced by this weight reduction, it is possible to reduce the weight and the size of other members that interlock with the inertial force, and further reduce the weight of the reciprocating device as a whole.

In any case, when the high-rigidity portion of the present invention is provided, since it has high rigidity and is lightweight, the degree of freedom in designing the reciprocating member is significantly increased, and the reciprocating device is made lightweight and compact. It is easy to improve performance and expand design flexibility.

[0101]

Since the reciprocating member of the present invention is made of an iron-based composite material having a high Young's modulus and a low density, it is easy to reduce the deformation of the reciprocating member and the inertial mass.
Therefore, the degree of freedom in designing the reciprocating member has been remarkably expanded, and it has become possible to provide a reciprocating member and a reciprocating device capable of meeting various required performances that have not been available in the past.

[Brief description of drawings]

FIG. 1 is a diagram comparing specific Young's moduli (E / ρ) of various metal materials.

FIG. 2 is a cross-sectional view showing a piston pin, a connecting rod, and a piston that are embodiments of the present invention.

FIG. 3 is a sectional view showing a piston pin according to an embodiment of the present invention.

FIG. 4 is a front view showing a connecting rod that is an embodiment of the present invention.

5 is a diagram showing a piston which is an embodiment of the present invention, FIG. 5 (a) is a bottom view of the piston, and FIG. 5 (b) is a line A-A shown in FIG. 5 (a). FIG.

FIG. 6 is a cross-sectional view showing a reciprocating member of a valve train that is an embodiment of the present invention.

FIG. 7 is an overall view showing a cotter and a retainer according to an embodiment of the present invention.

FIG. 8 is an image diagram showing expected deformation of a piston pin.

FIG. 9 is a schematic diagram showing a radial crush test of a piston pin.

FIG. 10 is a graph showing the relationship between bending load and strain between the first to third examples of the present invention and the comparative example.

FIG. 11 is a graph showing the relationship between bending load and strain between the fourth to sixth examples of the present invention and the comparative example.

[Explanation of symbols]

300 piston pins 400 connecting rod 500 pistons 710 rocker arm 720 cotter 730 retainer 750 valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F16J 10/00 F16J 10/00 A (72) Inventor Fumio Nonoyama, Nagakute-cho, Aichi-gun, Aichi Nagakage-cho, Yokochi 41 1 share Company Toyota Central Research Laboratories (72) Inventor Taku Saito Aichi Prefecture Nagachite Town, Aichi-gun, Nagakage 1 41, Yokomichi Toyota Central Research Laboratories, Ltd. (56) Reference JP-A-7-188874 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) C22C 38/00-38/16

Claims (8)

(57) [Claims] 1. A main component of iron is 1 to 5% by weight of copper (Cu).
In the matrix phase containing , 4 % group (titanium group) boride as a main component of the strengthening phase is 100% by volume as a whole.
When dispersed , the Young's modulus (longitudinal elastic modulus) E is 230 GPa or more and the density ρ is 7.5.
A reciprocating member having a high-rigidity portion made of an iron-based composite material of (10 ³ × Kg / m ³ ) or less. 2. The high rigidity portion has a specific Young's modulus E / ρ of 30.
The reciprocating member according to claim 1, wherein the reciprocating member is (× 10 ⁻³ GPa · m ³ / Kg) or more. 3. The reciprocating member according to claim 1, wherein the high-rigidity portion has a yield strength (0.2% yield strength) of 510 MPa or more. Wherein said high-rigidity section, with respect to the reinforcing phase 60
The reciprocating member according to claim 1, wherein the reciprocating member is composed of a non-matrix phase of not more than volume%. 5. The strengthening phase is titanium diboride (Ti).
The reciprocating member according to claim 4, wherein B ₂ ) is a main component, and the non-matrix phase is a boride other than the titanium diboride (TiB ₂ ) and / or a titanium compound as a main component. 6. The matrix phase contains 0.5% by weight or less of carbon (C), molybdenum (Mo), niobium (Nb), and tungsten (W) when the entire matrix phase is 100% by weight. One or more kinds of metal elements in total of 10% by weight or less from the metal group consisting of and tantalum (Ta) and one kind of metal elements in total of 25% by weight or less from the metal group consisting of vanadium (V) and chromium (Cr) The reciprocating member according to claim 1, comprising at least one kind of element selected from the element group consisting of the above metal elements. 7. The matrix phase contains 0.1 to 3% by weight of vanadium (V) and / or 0.5 to 4% by weight of chromium (Cr), based on 100% by weight of the whole matrix phase. The reciprocating member according to claim 1, wherein the reciprocating member includes: and substantially no carbon or 0.5 wt% or less. 8. The reciprocating member according to claim 1, wherein the reciprocating member is a piston pin at least a part of which is composed of the high rigidity portion.