JP2004284472A - Subframe for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a subframe for a vehicle which is interposed between a body of an automobile and a suspension device, that is a so-called suspension, enhances rigidity, and reduces the weight thereof while maintaining rigidity. <P>SOLUTION: The subframe for the vehicle which is interposed between a body of an automobile and a suspension device, that is a so-called suspension, is formed of metal containing at least one of carbon fiber and fullerene which is spherical shell-like carbon. The carbon fiber is carbon nano fiber of a mean diameter of 0.7-500 nm and a mean length of 0.01-1,000 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a vehicle subframe interposed between a vehicle body and a suspension device, ie, a suspension.
[0002]
[Background Art]
2. Description of the Related Art Conventionally, a vehicle subframe is interposed between a vehicle body of a motor vehicle and a suspension device, ie, a suspension, and attached with arms such as an upper arm and a lower arm of the suspension device. In particular, various components such as an engine and a steering device are mounted on a front subframe arranged in front of the body of an automobile.
[0003]
BACKGROUND ART In order to reduce the weight of a vehicle subframe, there is a structure in which a plurality of members made of aluminum alloy pipes are welded in a crossbeam shape (for example, see Patent Document 1). Similarly, there is a vehicle subframe manufactured using a cast aluminum alloy to reduce the weight of the vehicle subframe (for example, see Patent Document 2).
[0004]
However, in a conventional lightweight aluminum alloy vehicle subframe, aluminum itself has a lower rigidity, particularly toughness, than iron, and thus requires a rib structure or a buildup for reinforcement. These rib structures and overlaying not only reduce the design difficulty of the vehicle subframe, but also reduce the weight reduction effect of the material.
[0005]
[Patent Document 1]
JP-A-11-348812 (pages 1-3, FIG. 1)
[Patent Document 2]
JP-A-11-80875 (pages 1-5)
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle subframe capable of improving rigidity and reducing the weight while maintaining the rigidity.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a vehicle subframe for connecting a vehicle body and a wheel according to a first aspect of the present invention is formed of a metal containing at least one of carbon fiber and fullerene that is spherical shell carbon. Is done.
[0008]
According to the first aspect of the present invention, the rigidity, particularly the fracture toughness, can be improved by being formed of a metal containing at least one of carbon fiber and fullerene, and the vehicle sub-frame while maintaining the rigidity Can be reduced in weight.
[0009]
Here, in the vehicle subframe according to the first aspect of the present invention,
The carbon fibers may be carbon nanofibers having an average diameter of 0.7 to 500 nm and an average length of 0.01 to 1000 μm.
[0010]
With such a configuration, the rigidity, particularly toughness, of the vehicle subframe can be improved.
[0011]
Here, in the vehicle subframe according to the first aspect of the present invention,
The metal can be aluminum or an aluminum alloy.
[0012]
With such a configuration, the rigidity of the vehicle subframe can be improved, and the weight can be reduced while maintaining the rigidity. As a result, it is possible to contribute to reducing the weight of the vehicle body of the vehicle, and it is possible to reduce carbon dioxide by improving the fuel efficiency of the vehicle.
[0013]
Here, in the vehicle subframe according to the first aspect of the present invention,
The metal can be magnesium or a magnesium alloy.
[0014]
With such a configuration, the rigidity of the vehicle sub-frame can be improved, and the weight can be reduced while maintaining the rigidity. As a result, it is possible to contribute to reducing the weight of the vehicle body of the vehicle, and it is possible to reduce carbon dioxide by improving the fuel efficiency of the vehicle.
[0015]
Here, in the vehicle subframe according to the first aspect of the present invention,
The carbon nanofiber may be subjected to an ion implantation process.
[0016]
With such a configuration, the ion-implanted carbon nanofiber has at least a change in the chemical composition of its surface, and thus has an adhesive property between the metal (aluminum, magnesium, etc.) constituting the subframe and the carbon nanofiber. In addition, the stiffness of the vehicle subframe, especially the toughness, can be further improved, and the dispersibility of the carbon nanofibers in the metal can be improved, so that the overall performance can be uniform. .
[0017]
Here, in the vehicle subframe according to the first aspect of the present invention,
The carbon nanofiber may be subjected to a sputter etching process.
[0018]
With such a configuration, the carbon nanofibers subjected to the sputter etching process have fine irregularities formed on the surface thereof, and thus the adhesiveness between the metal (aluminum, magnesium, etc.) constituting the subframe and the carbon nanofibers. In addition, the stiffness of the vehicle subframe, especially the toughness, can be further improved, and the dispersibility of the carbon nanofibers in the metal can be improved, so that the overall performance can be uniform. .
[0019]
Here, in the vehicle subframe according to the first aspect of the present invention,
The carbon nanofiber can be plasma-treated.
[0020]
With such a configuration, the carbon nanofibers subjected to the plasma treatment are subjected to surface modification such as formation of fine irregularities on the surface thereof, so that the metal (aluminum, magnesium, etc.) constituting the vehicle subframe is formed. The adhesiveness and wetting of carbon nanofibers are improved, and the rigidity, especially toughness, of the subframe for vehicles can be further improved. Performance.
[0021]
Here, in the vehicle subframe according to the first aspect of the present invention,
The fullerene includes carbon 60 and carbon 70,
The carbon 60 may be contained more than the carbon 70.
[0022]
With such a configuration, in the process of synthesizing fullerene, carbon 60 synthesized more than carbon 70 can be effectively used. In particular, since fullerene has high dispersibility in metal, uniform characteristics can be obtained in the entire vehicle subframe.
[0023]
Here, in the vehicle subframe according to the first aspect of the present invention,
The metal may contain carbon and a carbon compound obtained in a synthesis process of at least one of the carbon nanofiber and the fullerene.
[0024]
With such a configuration, carbon and carbon compounds, which are impurities synthesized, can be effectively used in the process of synthesizing carbon nanofibers and / or fullerenes.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0026]
FIG. 1 is a schematic plan view of a vehicle showing an arrangement of subframes according to one embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an omnidirectional ion implantation apparatus, and FIG. 3 is a partial cross-sectional view showing another embodiment of the turntable.
[0027]
A subframe according to an embodiment of the present invention is disposed between a front subframe 10 disposed between front tires 2 and 2 and rear tires 3 of a vehicle body 1 of an automobile as shown in FIG. 1, for example. And a rear sub-frame 20. The structure and number of subframes are not particularly limited because they vary depending on the type of vehicle, the suspension system employed, and the like. Therefore, the detailed structure of the subframe will not be described here.
[0028]
The front subframe 10 has one end of an unillustrated upper arm or lower arm of, for example, a double wishbone type suspension member 4 supporting the front tires 2, 2, and is rotatably connected via a bush or the like. In an automobile having an engine mounted on the front side of the vehicle body 1, the front sub-frame 10 supports a part of the engine (not shown) and turns the front tires 2 and 2 such as a steering device (not shown). Parts can also be attached. The front sub-frame 10 is attached to the vehicle body 1 by combining a front member 12, a side member 14, and a rear member 16 in a cross-girder shape, for example, as shown in FIG.
[0029]
The rear sub-frame 20 is rotatably connected to one end of a semi-trailing arm (not shown) of, for example, a semi-trailing arm type suspension member 5, 5 that supports the rear tires 3, 3.
[0030]
In the present embodiment, the front sub-frame 10 and the rear sub-frame 20 (hereinafter, referred to as sub-frames) use aluminum for ease of manufacture and the like. However, if they are made of metal, they contribute to weight reduction. It can be appropriately selected from so-called light metals such as aluminum, aluminum alloy, magnesium, and magnesium alloy.
[0031]
The method for forming the subframe of the present invention is not particularly limited, but it can be manufactured by forging, casting, powder metallurgy, metal injection molding (MIM), or the like. In the present embodiment, manufactured by gravity casting, first, at least one of carbon nanofiber and fullerene is mixed into a metal melt (aluminum melt), and the metal melt (aluminum melt) is placed in a cavity formed by a mold. Fill and press. After the molten metal is solidified, for example, the front member 12 of the sub-frame is taken out of the cavity and subjected to a desired cutting process to obtain the front member 12 as a final product. Similarly, the side member 14, the rear member 16 and the rear subframe 20 are obtained.
[0032]
Preferably, the subframe contains 0.01 to 50% by weight of carbon fiber and fullerene in total. If the proportion of carbon fiber and fullerene exceeds 50% by weight, moldability is not preferred. If it is less than 0.01% by weight, toughness may not be sufficiently improved. When the carbon fiber and the fullerene are each independently contained, the above weight ratio is the weight percentage of the carbon fiber and the fullerene alone.
[0033]
Further, it is preferable to use carbon nanofibers having an average diameter of 0.7 nm to 500 nm and an average length of 0.01 to 1000 μm as the carbon fibers to be mixed with the metal such as aluminum. The amount of the carbon nanofiber is 0.01 to 50% by weight in the metal of the subframe, for example, aluminum, from the viewpoints of fluidity during molding, rigidity of the obtained subframe, particularly toughness, and the like. Is preferred. Such a carbon nanofiber is a so-called carbon nanotube having a single-layer structure in which a graphene sheet having a carbon hexagonal mesh surface is closed in a cylindrical shape or a multilayer structure in which these cylindrical structures are nested. The carbon nanotube may be composed of only a single-layer structure or only a multi-layer structure, and may be a mixture of a single-layer structure and a multi-layer structure. Further, a carbon material partially having a carbon nanotube structure can also be used. In addition, it may be called by a name such as graphite fibril nanotube other than the name carbon nanotube.
[0034]
The single-walled carbon nanotube or the multi-walled carbon nanotube is manufactured to a desired size by an arc discharge method, a laser ablation method, a vapor phase growth method, or the like.
[0035]
The arc discharge method is to obtain multi-walled carbon nanotubes deposited on a cathode by performing arc discharge between electrode materials made of carbon rods in an atmosphere of argon or hydrogen at a pressure slightly lower than atmospheric pressure. Further, the single-walled carbon nanotube is obtained by mixing a catalyst such as nickel / cobalt into the carbon rod, performing arc discharge, and soot adhering to the inner surface of the processing container.
[0036]
In the laser ablation method, a carbon surface mixed with a catalyst such as nickel / cobalt as a target is irradiated with a strong pulsed laser beam of a YAG laser in a rare gas (eg, argon) to melt and evaporate the carbon surface. This is to obtain a single-walled carbon nanotube.
[0037]
The vapor phase growth method is a method in which hydrocarbons such as benzene and toluene are thermally decomposed in a gas phase to synthesize carbon nanotubes, and examples thereof include a fluidized catalyst method and a zeolite supported catalyst method.
[0038]
Before the carbon nanofiber is mixed with a metal such as aluminum, a surface treatment such as an ion implantation treatment, a sputter etching treatment, and a plasma treatment can be performed in advance to improve the adhesiveness and wettability with aluminum.
[0039]
(Ion implantation processing)
Ion implantation is a process in which necessary energy is given to an element ionized by an ion source, such as oxygen, by an accelerator, and ions are implanted in the surface of a carbon nanofiber in a vacuum chamber maintained in a high vacuum state by a vacuum pump. It is something to drive.
[0040]
The ion implantation processing according to one embodiment of the present invention will be described with reference to the schematic configuration diagram of the omnidirectional ion implantation apparatus shown in FIG. In the omnidirectional ion implantation apparatus 50, a rotary table 53 for placing a sample (for example, carbon nanofiber 52) to be subjected to an ion implantation process is rotatably arranged in a vacuum chamber 51 made of, for example, stainless steel connected to a vacuum pump 57. I have. The turntable 53 is connected to a pulse bias power supply 54, and is insulated from the vacuum chamber 51 by an insulator 55. The vacuum chamber 51 is connected to a process gas supply device 58, a coil 60 connected to a high frequency power supply 59, an arc evaporation source 61, and an infrared radiation thermometer 62 for measuring the temperature inside the vacuum chamber 51.
[0041]
In the ion implantation process, a gas is supplied from a process gas supply device 58 into a vacuum chamber 51 which is brought into an appropriate vacuum state by a vacuum pump 57, and a plasma is generated around a coil 60 by a high frequency power supply 59. The gas ionized thereby is drawn into a sample, for example, the carbon nanofiber 52 connected to the negative electrode of the pulse bias power supply 54 and injected. Further, metal ions can be injected into the sample, for example, the carbon nanofibers 52 by the arc evaporation source 61 connected to the vacuum chamber 51. In this case, the metal evaporation source in the arc evaporation source 61 is connected to a DC arc power supply (not shown), and is evaporated by arc discharge. At this time, since the rotating table 53 and the sample, for example, the carbon nanofibers 52 are applied by the negative DC bias power source 56 switched by the switch 63, the metal ions are injected into the sample, for example, the carbon nanofibers 52.
[0042]
Further, the rotary table 53 of the omnidirectional ion implanter 50 may have a structure having a stirring blade 53a and a container 53b as shown in FIG. The container 53b has a wide opening at the top, and a sample such as the carbon nanofiber 52 can be arranged in the container 53b. During the ion implantation process, the powder sample such as the carbon nanofibers 52 can be uniformly and entirely subjected to the ion implantation process by being stirred by the rotation of the stirring blades 53a. The rotation speed of the stirring blade 53a can be appropriately adjusted depending on the amount of the carbon nanofibers 52, the ion implantation processing time, and the like.
[0043]
The surface of the ion-implanted carbon nanofiber is chemically modified, and the wettability and adhesiveness of the subframe to metal, such as aluminum, are improved, and the rigidity of the subframe, particularly the fracture toughness, is improved. .
[0044]
Elements used for the ion implantation process include, for example, oxygen (O), nitrogen (N), chlorine (Cl), chromium (Cr), carbon (C), boron (B), titanium (Ti), and molybdenum (Mo). , Phosphorus (P), aluminum (Al), etc., can be appropriately selected depending on the compatibility with the metal of the subframe, for example, aluminum.
[0045]
(Sputter etching treatment)
In the dry etching sputter etching process, glow discharge is performed by applying an alternating current in an etching gas or an ultra-low pressure inert gas atmosphere such as argon (Ar) in a vacuum chamber maintained in a high vacuum state by a vacuum pump. In addition, etching is performed by colliding ions with the surface of the carbon nanofiber in contact with the electrode exposed in the plasma generated by the glow discharge.
[0046]
The surface of the carbon nanofiber that has been subjected to the sputter etching treatment is physically etched to form fine (nano-sized) irregularities. The irregularities on the surface of the carbon nanofibers increase the contact area of the subframe with the metal, for example, aluminum, and can improve the adhesive strength between aluminum and the carbon nanofibers. The rigidity, particularly the fracture toughness, of the subframe manufactured by mixing carbon nanofibers with aluminum can be improved. Moreover, the sub-frame manufactured by mixing carbon nanofibers into aluminum as described above has improved heat dissipation, and can efficiently radiate heat from the knuckle 10.
[0047]
(Plasma treatment)
The plasma treatment modifies the surface by irradiating the carbon nanofibers with plasma. As the plasma processing, general glow discharge processing, corona discharge processing, or the like can be employed.
[0048]
For example, a plasma applies a high-voltage / high-frequency pulse voltage generated by a pulse generation circuit between a discharge electrode and a counter electrode facing each other, causing a corona discharge between the two electrodes and causing a plasma in the air. Is caused to occur. The object to be processed is arranged in a stationary state or a moving state between the two electrodes, and its surface is subjected to plasma processing.
[0049]
The method of plasma generation is a bipolar discharge type in which a voltage of several hundred to several thousand volts is applied to two parallel flat electrodes to discharge them. A large amount of electrons emitted from a hot cathode collide with gas molecules before entering the anode. Thermionic discharge type that generates plasma, magnetron discharge type that discharges in a high vacuum using a magnetic field, electrodeless discharge type that generates plasma by high-frequency electromagnetic induction, ECR that sends microwaves to a resonance chamber with a magnetic field to resonate electrons (Electron Cyclotron Resonance) discharge type and the like can be selected as appropriate.
[0050]
The surface of the carbon nanofiber treated in this way has improved adhesion and wettability with the metal of the subframe, for example, aluminum, and the rigidity, particularly fracture toughness, of the subframe manufactured by mixing carbon nanofiber into aluminum. Is obtained.
[0051]
The fullerene used in the present embodiment includes spherical shell carbon such as fullerenes such as carbon 60 (hereinafter referred to as C60), C70, C74, C76, C78, C82, C84, C720, and C860. Is preferably a main component. Further, it is preferable to use fullerene containing C60 as a main component and containing C70 in a smaller amount than C60. Further, C60 may be the main component, and may include other fullerenes, or may include other carbon and carbon compounds simultaneously generated when fullerene other than fullerene is generated. The form of the fullerenes may be, for example, a soccer ball shape, a bucky ball shape, or the like.
[0052]
Further, the fullerenes may be modified by introducing a substituent or the like. The modification method is not particularly limited, and for example, a 5-membered carbon ring portion of a fullerene having high reactivity can be chemically modified. The type of the substituent is not particularly limited, and examples thereof include an alkyl group, an aryl group, an aralkyl group, a dioxolane unit, a halogen or an oxygen atom, and the like, and the modification may be performed by introducing a liquid crystal polymer, a dye, polyethylene oxide, or the like. Good. Modification of fullerenes allows for improved affinity with selected metals, such as aluminum, and dispersion of fullerenes.
[0053]
C60 fullerene was subjected to arc discharge in a helium atmosphere using a graphite electrode, the resulting soot was extracted with benzene, and the resulting C60 mixture was purified by column separation using basic activated alumina as a carrier and hexane as a developing solvent. Prepared. The method for obtaining fullerene is not limited to the arc discharge method, but may be another method.
[0054]
As described above, the rigidity, particularly the fracture toughness, of the subframe manufactured by mixing fullerene into the metal of the subframe, for example, aluminum, can be improved.
[0055]
It should be noted that the present invention is not limited to the present embodiment, and can be modified into various forms within the scope of the present invention.
[0056]
For example, aluminum or an aluminum alloy constituting the subframe, a composite material in which magnesium or a magnesium alloy is mixed by several percent, for example, aluminum, a metal containing magnesium as a main component, and another metal may be mixed. .
[Brief description of the drawings]
FIG. 1 is a schematic plan view of a vehicle showing an arrangement of subframes according to an embodiment of the present invention.
FIG. 2 is a schematic explanatory view of an omnidirectional ion implantation apparatus used in one embodiment of the present invention.
FIG. 3 is a partial sectional view showing another embodiment of the turntable of the omnidirectional ion implantation apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Body 2, 3 Tires 4, 5 Suspension device 10 Front subframe 20 Rear subframe 50 Omnidirectional ion implanter 53 Rotary table 53a Stirrer blade 53b Container

Claims (9)

In a vehicle subframe interposed between a vehicle body and a suspension device,
A vehicle sub-frame formed of a metal containing at least one of carbon fiber and fullerene that is spherical shell carbon. The vehicle sub-frame according to claim 1,
The subframe for vehicles, wherein the carbon fiber is a carbon nanofiber having an average diameter of 0.7 to 500 nm and an average length of 0.01 to 1000 μm. The vehicle subframe according to claim 1 or 2,
The sub-frame for a vehicle, wherein the metal is aluminum or an aluminum alloy. The vehicle subframe according to claim 1 or 2,
The subframe for a vehicle, wherein the metal is magnesium or a magnesium alloy. In any of the vehicle sub-frames according to claims 2 to 4,
The sub-frame for a vehicle, wherein the carbon nanofiber is subjected to an ion implantation process. In any of the vehicle sub-frames according to claims 2 to 4,
The vehicle sub-frame, wherein the carbon nanofiber is subjected to a sputter etching process. In any of the vehicle sub-frames according to claims 2 to 4,
The vehicle sub-frame, wherein the carbon nanofiber is plasma-treated. In any of the vehicle subframes according to claim 1,
The fullerene includes carbon 60 and carbon 70,
A vehicle subframe containing more carbon 60 than carbon 70. In any of the vehicle sub-frames according to claims 2 to 8,
The vehicle subframe, wherein the metal contains carbon and a carbon compound obtained in a synthesis process of at least one of the carbon nanofiber and the fullerene.

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