JP5042466B2 - Direct receiving connecting rod and manufacturing method thereof - Google Patents

Description

The present invention relates to a connecting rod. More specifically, the present invention relates to a direct receiving connecting rod that directly supports a crankshaft without using a half-circular plain bearing connected to the large end of a connecting rod of an internal combustion engine, and its It relates to a manufacturing method.
The cran shaft is made of carbon steel such as S50CQT, alloy steel such as SCM440QT, non-heat treated steel such as V-added S45C, cast iron such as FCD70, and may be subjected to surface treatment such as soft nitriding. Carbon steel, alloy steel, non-heat treated steel, sintered forged steel, etc. are used for the connecting rod.

  In JP-A-10-339316, a bearing is provided on the main body side of the connecting rod large end, a bearing is not provided on the cap side, and the crankshaft is directly received. Providing a Sn or Pb based overlay or a resin based coating. Further, a direct receiving structure in which a sliding bearing copper alloy is sprayed onto a connecting rod sliding surface is also known. In this way, by adopting a direct receiving structure that eliminates the sliding bearing, it is expected to achieve a weight reduction of several percent with respect to the total weight of the connecting rod and the crankshaft, particularly by reducing the weight of the back metal. .

  The operating condition of the diesel engine described in Patent Document 1 is that the surface pressure applied to the bearing on the connecting rod body side is 80 to 110 MPa, and the surface pressure on the cap side opposite to the connecting rod body is about 20 to 25 MPa. In consideration of such conditions, in Patent Document 1, only the cap side has a direct receiving structure. Furthermore, it is considered that the cap side provided with the Sn or Pb-based overlay or the resin-based coating operates under the surface pressure of 20 to 25 MPa.

According to Non-Patent Document 1, Proceedings of Tribology Conference of Japan Tribology Society (Tokyo 1999-5, A12, Development of Slide Bearing Materials for Engines with Solid Lubrication Overlay (1st Report)), Al Alloys for Slide Bearings (Al-12.5Sn) -2.7Si-1Cu-0.2Cr-2Pb rolled material), MoS ₂ added epoxy resin is applied and baked by spraying as an overlay with good fluid lubrication and good initial conformability. However, it has been reported that it does not burn.

An aluminum sliding bearing alloy having a composition of Al-20% Sn-0 to 3% Cu, with Al ₂ O ₃ particles dispersed as necessary, is deposited on the support by cathode sputtering, and a sliding layer Is described in Japanese Patent Application Laid-Open No. 55-81147. This sputtered Al-Sn alloy has a hardness of Hv130 and is described in Patent Document 2 which states that it does not wear at all under the test conditions of load 170 N / mm ² (170 MPa), 160 ° C., 250 hours. Although the -Sn alloy is excellent as a so-called bearing material, it is estimated that it is not suitable as an overlay utilizing wear.

Patent Document 3 discloses that an aluminum alloy overlay comprising Si 0.5 to 6%, Pb 5 to 40%, Sn 0.5 to 10%, and the balance Al is formed on a bimetal obtained by rolling an aluminum alloy on a low carbon steel backing metal. Japanese Patent Laid-Open No. 7-90551. The overlay sputtered Al-based alloy proposed in Patent Document 3 is one in which a large amount of Pb, which is difficult to be alloyed by an ordinary melting method, is added to aluminum, thereby reducing the overall hardness of the alloy and expressing the familiarity. . Although it is clear from Patent Document 2 that the sputtered overlay has a fine and uniform structure and high hardness, it is clear from Patent Document 2 that the maximum surface pressure without seizure in the embodiment of Patent Document 3 1350kg / cm ² (13MPa) is relatively low. This is thought to be due to the addition of a large amount of Pb.
JP 10-339316 A JP-A-55-81147 Japanese Patent Laid-Open No. 7-90551 JP-A-7-247493 Tribology Conference Proceedings of the Japan Society of Tribology (Tokyo 1999-5, A12, Development of connecting rod materials for engines with solid lubricant overlay (1st report) Automotive Technology Vol59, No.2, 2005, p25 ~ 28

The present applicant industrialized the plain bearing of Non-Patent Document 1 and incorporated it as a semi-circular plain bearing (so-called “metal”) in a mass-produced vehicle having a bearing surface pressure guarantee performance of 80 to 100 MPa. In the process of developing to meet the required surface pressure guarantee performance of 100 to 120MPa, the MoS ₂ -coated bearing proposed in Non-Patent Document 1 has sufficient sliding performance under high surface pressure exceeding 100MPa. I understood that it was not. More specifically, the familiarity of MoS ₂ coatings can hardly be realized. Therefore, this phenomenon was considered as follows. In general, the conformability of the overlay can be explained by abrasive wear, and the conformability becomes better when the hardness of the overlay is lower. In other words, it can be explained that the softer the overlay, the more likely the abrasive wear occurs, and the more prominent the property of adapting to the unevenness of the counterpart shaft. On the other hand, the load generally tends to promote abrasive wear, so it seems to have good compatibility, but as a result, the compatibility is impaired.

  In the direct receiving structure connecting rod, the surface pressure resistance performance of the conventional Pb, Sn or resin-based overlay is about 20-25 MPa (Patent Document 1), and the Al-Pb overlay is about 13 MPa (Patent Document 3). It is considered to be considerably lower than the surface pressure resistance performance of the semicircular plain bearing.

Therefore, as a result of intensive studies on improving the sliding performance under high surface pressure in the connecting rod having a direct receiving structure, the present inventors can improve the expected by combining known techniques, and conversely combine them. Has been found that there are unfavorable known techniques.

The connecting rod according to the present invention is characterized in that an Al—Sn alloy is deposited on the entire sliding surface of the connecting rod by sputtering, and a MoS ₂ -resin overlay is applied and baked on the Al—Sn alloy. . The features of the present invention will be described below.

  Since the wear test conditions of the sputtered Al—Sn alloy described in Patent Document 2 are very severe, it can be said that the wear resistance of the sputtered Al—Sn alloy that does not wear under these conditions is very good. Compared with general Al rolled alloys, even Al-Si alloys with excellent wear resistance wear somewhat, so the sputtered Al-Sn alloy has a refined structure, so the wear resistance is significantly improved. It is thought that.

Since the present inventors have excellent wear resistance, the sputtered Al—Sn alloy has the idea that when combined with the MoS ₂ coating overlay of Non-Patent Document 1, it is used as an overlay for a direct receiving structure connecting rod. embraced. The background behind this idea is that when the sliding characteristics of a sputtered Al—Sn alloy without MoS ₂ + resin-based coating overlay were studied, no abrasion occurred as reported in Patent Document 2. However, it has been found that as a remarkable wear phenomenon, a wear problem occurs due to contact with the mating shaft under a high load. The uneven contact wear of the sputtered Al-Sn alloy had a possibility to solve the MoS ₂ + resin coating overlay.

Conventionally, the following means have been implemented as countermeasures against wear per piece of a slide bearing.
(1) Improvement of bearing processing accuracy (2) Covering with overlay (3) Crowning (Non-Patent Document 2, page 28)

First, the measure (1) has a limit in processing accuracy even with a slide bearing, and in the case of a connecting rod, the number of processing steps is larger than that of a sliding bearing, so that it is difficult to apply to a direct receiving connecting rod.
Next, in measure (3), for example, a half-shaped bimetal is deformed so as to increase the clearance between the shaft and the bearing at the end in the axial direction where contact is likely to occur. However, this processing method is very complicated and is difficult to apply to a direct receiving connecting rod.

The MoS ₂ coating overlay proposed in Non-Patent Document 1 corresponds to measure (2) and can be applied to a direct receiving connecting rod, but does not function under high surface pressure. Surprisingly, however, it has been found that if a sputtered Al—Sn alloy film is formed on the underlayer, wear per piece can be prevented. That is, by itself, sputtered Al-Sn alloys have poor conformability and are likely to cause wear per piece, while MoS ₂ + PAI (PI) overlay alone does not provide a measure for wear per piece, but these must be combined. As a result, the surface pressure resistance was improved. Further, Cu-Sn-based plain bearing alloy which has been used conventionally, when combined with the sputtering Al-Sn-based alloy and / or MoS ₂ + PAI (PI) based overlay, it found not effective in partial contact performance It was. It is assumed that the cause of these series of phenomena is that the hardness of the overlay surface on which abrasive wear has occurred is influenced by the substrate, but elucidation of the wear mechanism is a future issue.
When the above prior art and the knowledge of the present inventor are arranged, the conventional sputtered Al-Sn alloy and the solid lubricating overlay are both insufficient in performance under high surface pressure. It was possible to secure the conformability at the time of piece contact and the seizure resistance at the time of initial contact. Subsequently, preferred embodiments of the present invention will be described.

FIG. 1 shows a cross-sectional view of a direct receiving connecting rod according to the present invention, in which 1 is a connecting rod, 1a is a main body, 1b is a cap, 2 is a sputtered Al—Sn alloy, 3 is a MoS ₂ + resin overlay ( 5 is a bolt for assembling 1a and 1b. FIG. 2 shows the layer structure. In order to improve adhesion between the sputtered Al—Sn alloy 2 and the connecting rod, a Ni-based or Ni—Cr-based intermediate layer is provided on the connecting rod by plating, sputtering, or Ni-based self-fluxing alloy is sprayed. Can do.

  According to a preferred embodiment of the present invention, the hardness of the sputtered Al—Sn alloy 2 is HV 40-100 and the hardness of the solid lubricant overlay 3 is HV 10-60. The reason why these ranges are preferable is that when the hardness of the sputtered Al—Sn alloy 2 and the solid lubricant overlay 3 is less than the above lower limit, the fatigue resistance decreases, and when the hardness exceeds the upper limit, the conformability decreases. More preferably, the hardness of the sputtered Al—Sn alloy 2 is HV50-80, and the hardness of the solid lubricant overlay 3 is HV15-25.

According to another preferred embodiment of the present invention, the thickness of the sputtered Al—Sn alloy is 5 to 500 μm and the thickness of the solid lubricant overlay is 3 to 20 μm. The reason why these ranges are preferable is that for sputtered Al—Sn alloys, there is a risk of direct contact between the connecting rod and the crankshaft if it is less than the lower limit, and if it exceeds the upper limit, cost increases.
If the solid lubricant overlay is less than the lower limit, the overlay is initially worn before fluid lubrication is achieved, whereas if the upper limit is exceeded, the Al-Sn alloy is not fully exposed when the fluid lubrication is achieved. And fatigue resistance becomes insufficient. More preferably, the thickness of the sputtered Al—Sn alloy is 10 to 50 μm, and the thickness of the solid lubricant overlay is 5 to 15 μm.

The composition of the Al—Sn alloy of the present invention is 5 to 50 mass% Sn, 0 to 1 mass% Ni, 0 to 3 mass% Cu, the balance Al and inevitable impurities, and the preferred composition of the overlay is 50 to 50 mass%. 90% by mass MoS ₂ , balance polyamideimide (PAI) or polyimide (PI). In an Al-Sn alloy, the conformability decreases when the Sn content is less than 5% by mass, and the strength decreases when the Sn content exceeds 50% by mass. The components of Ni and Cu enhance the wear resistance existing as hard fine particles, but if they exceed the upper limit, they become too hard and the conformability is impaired and seizure is likely to occur. Here, Ni and Cu are optional components and may be omitted. The overlay has good low friction and good adhesive strength in the above range, but if the MoS ₂ content is less than the lower limit, the lubrication performance is lowered, and if it exceeds the upper limit, it becomes brittle and easily peels off. More preferably, the composition of the Al—Sn alloy is 10 to 30 mass% Sn, 0 to 0.1 mass% Ni, 0 to 1 mass% Cu, the balance Al and unavoidable impurities, and the composition of the overlay is 60 to 85% by mass MoS ₂ , balance polyamideimide or polyimide.

Sputtering uses an Al-Sn mother alloy plate or an Al / Sn separate alloy plate as a cathode target to bombard Ar ions to knock out metal atoms and deposit them on the connecting rod sliding surface (anode). This sputtering method itself is known in Patent Documents 2 and 3.
The coating and baking of the solid lubricant overlay is performed by spraying, printing, etc., a mixture of solid lubricant and resin, if necessary, and then baking at 150-250 ° C. It is known from Document 4 and JP-A-7-247493.
Sputtering described above is performed when the rod-shaped target 10 penetrates the bore of the connecting rod 1 with the connecting rod body 1a and the cap 1b assembled as shown in FIG. The discrepancy of the dynamic layer can be eliminated.

Further, the above-described sputtering can be performed in a state where the connecting rod main body 1a and the cap 1b are divided as shown in FIG. The connecting rod body 1a and the cap 1b are held by chamber-like jigs 12a and 12b heated in the vacuum chamber 20 by the heater 11, and are rotated together with the heater 11 in a horizontal plane. The Al target 13 and the Sn target 14 arranged so as to face the connecting rod body 1a and the cap 1b are connected to a power source 15. The Ar gas having a charge opposite to that of the power source 15 collides with the targets 13 and 14 in the vacuum chamber 20 to generate Al vapor 16 and Sn vapor 17, respectively. These vapors are mixed and formed on the connecting rod 1 as an Al—Sn layer 2. By processing the connecting rod with the connecting rod body 1a and the cap 1b separated, work efficiency is improved when mass-produced, and the film near the mating surface when the connecting rod body 1a and the cap 1b are assembled after sputtering. The thickness is reduced, and this plays a role like a relief, so that it is possible to improve the foreign matter discharging property when sliding.
Subsequently, the present invention will be described in more detail by experimental examples.

A reciprocating sliding test was conducted on the connecting rod-corresponding specimens shown in Table 1 under the following conditions. Each characteristic is as follows.
Connecting rod equivalent substrate: SS400, Ni-30% Cr intermediate layer 0.5-1μm sputter sputtered Al-Sn alloy: HV70, thickness 20μm, Sn20% by mass
Solid lubricant overlay: A mixture of MoS ₂ and polyamideimide applied to a thickness of 6 μm (hardness HV20). However, the polyamide imide has the following material specifications manufactured by Hitachi Chemical Co., Ltd. Elongation: 7-20% at 25 ° C, 20% or more at 200 ° C
Tensile strength: 70 to 110 MPa at 25 ° C., 15 MPa or more at 200 ° C. In addition, specimens corresponding to a sliding bearing alloy sprayed structure were prepared as comparative examples (Comparative Examples 3 to 5).

Test conditions <br/> Oil type: CF4 10W-30
Oil temperature: 140 ° C
Load: 70MPa repeated several 10 ⁷ times → 78MPa repeated several 10 ⁷ → 86MPa seizure rotation speed up to: 3000 r / min
Mating shaft (equivalent to crankshaft): S55C

From the test results shown in Table 1, it can be seen that the seizure resistance of Examples 1 to 3 of the present invention is good, and the performance equivalent to or higher than that of Comparative Example 3 having the largest number of layers is achieved, and further 86 MPa seizure fatigue occurs. The surface pressure sufficiently satisfies the performance required for the connecting rod body.
The following evaluation is obtained for each comparative example.
(A) The solid lubricant single layer (Comparative Example 1) has the worst performance.
(B) Sputtered Al—Sn alloy single layer (Comparative Example 2) has the worst fatigue resistance.
(C) Comparative Example 3 in which a copper-based bearing alloy is coated with a solid lubricant is a technique that approximates Non-Patent Document 1, and shows the level of performance achieved by the conventional technique.
(D) Although Comparative Example 3 is superior to Comparative Example 4, it is a comparative example because it has a large number of layers and is not the best from the viewpoint of weight reduction.
(E) Al-Sn alloys are not suitable as overlays for Cu-based plain bearing alloys (Comparative Example 5).

Under the following conditions, a contact test was performed in which the connecting rod having the layer structure shown in Table 1 was fixed obliquely (tilt angle 0.08 °) with respect to the bearing, and the test results are shown in FIG.
Test condition Oil type: CF4 10W-30
Oil temperature: 140 ° C
Load: 0.5ton gradually increasing Rotation speed: 3000 r / min

From FIG. 5, it can be seen that the seizure load under the one-piece condition of the embodiment of the present invention is the highest. The following evaluation is obtained for each comparative example.
(A) The solid lubricant single layer (Comparative Example 1) has the worst performance.
(B) Sputtered Al—Sn alloy single layer (Comparative Example 2) significantly improves performance.
(C) Comparative Example 3 in which a copper-based bearing alloy is coated with a solid lubricant is a technique that approximates Non-Patent Document 1, and shows the level of performance achieved by the conventional technique. Comparing Example and Comparative Example 3, it can be seen that the copper-based plain bearing alloy does not improve the per-piece resistance performance but rather deteriorates it.
(D) Comparative Example 4 is almost the same as Comparative Example 1 and has poor performance.
(E) Comparative Example 5 having no solid lubricant overlay has a medium performance.

  As described above, the sliding layer of the present invention has excellent surface pressure resistance and wear resistance per piece, and can be provided on the connecting rod body side. Therefore, the direct receiving connecting rod according to the present invention can be further reduced in weight as compared with the connecting rod in Non-Patent Document 1.

It is drawing which shows the form of the connecting rod which concerns on this invention. 2 is a drawing showing a layer structure of the connecting rod of FIG. It is a conceptual diagram of the apparatus which deposits Al-Sn type alloy by sputtering to the assembled connecting rod sliding surface. It is a conceptual diagram of the apparatus which deposits an Al-Sn type alloy by sputtering on each sliding surface divided | segmented into the connecting rod main body and the cap. It is a graph which shows the result of a one-piece test.

Explanation of symbols

1-Connecting rod 2-Sputtered Al-Sn alloy 3-MoS ₂ + resin overlay

Claims (7)

Direct receiving layer comprising an Al-Sn alloy deposited by sputtering on the main rod side and cap side sliding surfaces of the connecting rod, and a MoS ₂ -resin-based overlay coated and baked on the Al-Sn alloy The composition of the Al-Sn alloy is 5-50 mass% Sn, 0-1 (including 0) mass% Ni, 0-3 mass% (including 0) mass% Cu. A direct receiving connecting rod characterized by remaining Al and inevitable impurities . _2. The direct connection connecting rod according to claim 1, wherein the hardness of the Al—Sn alloy is HV 40 to 100, and the hardness of the MoS ₂ -resin overlay is HV 10 to 60. The thickness of the Al-Sn-based alloy is 5 to 500 [mu] m, and the MoS ₂ - claim 1 or 2 straight-receiving connecting rod according thickness of the resin-based overlay is characterized by a 3 to 20 [mu] m. The MoS ₂ - straight-receiving connecting rod according to any one of composition 50 to 90 wt% MoS ₂ resin based overlay, claim 1, characterized in that the balance polyamide imide, and one or more polyimide to 3 . The sliding surface with the crankshaft is processed on the inner surface of the main body side and the cap side of the connecting rod in a state where the connecting rod main body and the cap are assembled, and then 5 to 50 mass% Sn, the remaining Al and Al consisting of inevitable impurities A method for producing a direct receiving connecting rod, comprising: depositing a -Sn alloy by sputtering and coating and baking a MoS ₂ -resin overlay on the Al-Sn alloy. In a state in which processing the sliding surfaces of the connecting rod main body and the cap and the crankshaft to the inner surface of the main body and the cap side of the state of the connecting rod is assembled, and then divided into a connecting rod body and the cap, 5 to 50 mass% A direct receiving connecting rod characterized in that an Al-Sn alloy composed of Sn, the balance Al and inevitable impurities is deposited by sputtering, and a MoS ₂ -resin overlay is applied and baked on the Al-Sn alloy. Production method. The Al-Sn alloy is sputter-deposited on the inner surface of the connecting rod on the main body side and cap side of the connecting rod that becomes the mating surface in the assembled state, and the MoS ₂ -resin overlay is applied and baked on the Al-Sn alloy. The manufacturing method of the direct receiving connecting rod of Claim 6 characterized by these.