JP2003278508A - Tappet roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the surface of a tappet roller bearing from being damaged in a non-lubricated condition immediately after start of an engine. <P>SOLUTION: On either of the outer periphery of a shaft 5 and the inner periphery of a roller 6 facing each other with a fine clearance, a surface treatment layer for friction reduction is formed. While engine oil is not still supplied immediately after the start of the engine, the surface treatment layer prevents both the peripheries from being damaged. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention A tappet roller bearing according to the present invention is incorporated in a valve train of an engine to reduce the friction of the valve train so that it can be used during engine operation. It is intended to reduce the fuel consumption rate. 2. Description of the Related Art For the purpose of reducing friction inside an engine and reducing the combustion consumption rate, rotation of a camshaft synchronized with a crankshaft is converted into reciprocating motion of an intake valve and an exhaust valve. It is common practice to incorporate tappet roller bearings into the parts. 1 and 2 show the actual opening 3-1.
1 shows a tappet roller bearing described in JP 08806. A rocker arm 3 is provided opposite to a cam 2 fixed (generally, integrally formed) to a camshaft 1 which rotates in synchronization with the crankshaft of the engine and which receives the movement of the cam 2. Have been. At the end of the rocker arm 3, a pair of support walls 4, 4 are provided at an interval from each other. The pair of support walls 4, 4
A hollow or solid shaft 5 made of steel is bridged between them.
The ends of the shaft 5 are not quenched and are left raw. When the shaft 5 is fixed, the unquenched portion is
It is caulked toward the inner peripheral surfaces of the through holes 18 formed in the pair of support walls 4. As described above, the roller 6 is rotatably supported around the shaft 5 bridged between the pair of support walls 4, 4, and the outer peripheral surface of the roller 6 2 is in contact with the outer peripheral surface. According to the tappet roller bearing configured as described above, the frictional force acting between the rocker arm 3 and the cam 2 can be reduced, and the fuel consumption rate during engine operation can be reduced. Engine oil is supplied to the installation portion of such a tappet roller bearing during operation of the engine. The engine oil lubricates between the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6 and between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6. It is necessary that the camshaft 1 including the cam 2 is made of cast iron or bearing steel, and the roller 6 and the shaft 5 are made of high carbon chromium bearing steel. It is generally used from the viewpoint of reducing material costs and processing costs while ensuring strength.
Then, by devising the gap size and the surface roughness between the peripheral surfaces of the members, lubrication of the sliding contact portions between the members during operation of the engine is ensured. In order to ensure such lubrication, the shaft 5 is made of phosphor bronze and the roller 6 is made of high carbon chromium bearing steel. Also, it has been conventionally proposed to open an oil supply hole for supplying the engine oil to the rocker arm 3 and the shaft 5 as described in Japanese Utility Model Laid-Open No. 4-32210. Further, the roller 6 may be made of a ceramic such as silicon nitride.
No. 5296, Japanese Utility Model Application Laid-Open No. Sho 62-203911, Japanese Utility Model Application Laid-Open No. 3-108806, and the like.
It has been conventionally proposed. [0006] However, in the case of the above-described tappet roller bearing known in the related art, there are the following points to be solved. First, when the camshaft 1 including the cam 2 is made of cast iron or bearing steel and the shaft 5 and the roller 6 are made of high carbon chromium bearing steel, depending on the operating conditions,
One or both of the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6;
Further, surface damage called smear occurs on one or both of the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6. Such surface damage is caused by a non-lubricating condition of the contact portion between the outer peripheral surfaces of the two members 5 and 6 and the contact portion between the outer peripheral surfaces of the two members 2 and 6 during the assembly operation. And occur.
That is, a processing oil such as a cutting oil that adheres at the time of machining, and a rust-preventive oil for preventing corrosion during transportation are attached to the surfaces of these members 2, 5, and 6. . If these oils remain, lubrication between the outer peripheral surfaces is achieved immediately after the start of operation of the engine. However, in the engine assembly process in recent years, these oils have been washed away with a minimum necessary amount of washing oil in order to prevent deterioration of the engine oil due to mixing into the engine oil. For this reason, in the engine immediately after assembly, the contact portion between the two outer peripheral surfaces is in a state close to non-lubrication. When the engine is started from this state, the peripheral surfaces rub strongly against each other for a short period of time until the supply of the engine oil without any lubrication. As a result, the above-mentioned surface damage occurs on each of these peripheral surfaces. If the surface damage thus generated is remarkable, there is a possibility that the contact portion between the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6 is seized. Also, even when the surface damage is slight, minute projections are formed on each of the above-mentioned peripheral surfaces, and even after the supply of engine oil is performed by these projections, sliding between these peripheral surfaces can be performed. It becomes difficult for the lubrication state of the part to be completely fluid lubrication. As a result, when the surface fatigue of each peripheral surface portion increases with time, or when the oil film formation cannot follow a rapid speed fluctuation, such as when the engine is rapidly accelerated or decelerated,
Significant localized surface damage can occur. or,
Devising the surface roughness of the peripheral surface of each member 2, 5, 6 itself,
It is intended to make effective use of the supplied engine oil and does not help prevent surface damage in an unlubricated state. Further, if the outer peripheral surface of the phosphor bronze shaft 5 and the outer peripheral surface of the roller 6 made of high carbon chromium bearing steel are brought into contact, dissimilar metals come into contact with each other. I do. However, in this case, the material cost and the processing cost of the shaft 5 increase. In addition, the effect of preventing surface damage in an unlubricated state is insufficient. Further, if the roller 6 is made of a ceramic such as silicon nitride, the material cost and processing cost of the roller 6 increase.
Further, the ceramic roller 6 is not only easily broken than a metal roller, but also has a strong aggressiveness to the metal cam 2 and easily wears the outer peripheral surface of the cam 2 significantly. Furthermore,
Since the ceramic roller 6 has a smaller amount of thermal expansion than the metal shaft 5, the change in the gap between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6 due to the operation and stop of the engine increases. For this reason, when the temperature of the engine is low, problems such as generation of vibration at the support portion of the roller 6 are likely to occur. The tappet roller bearing of the present invention has been invented in order to solve any of these problems. The tappet roller bearing of the present invention has the same structure as the above-described conventional tappet roller bearing.
A cam fixed to a camshaft that rotates in synchronization with a crankshaft of the engine, and a pair of support wall portions provided opposite to the cam and formed with a space between members receiving the movement of the cam; The shaft comprises a shaft suspended between the pair of support walls, and a roller rotatably supported around the shaft. In particular, in the tappet roller bearing according to the present invention, the surface of at least one of a plurality of members relatively displaced with respect to a mating member with the rotation of the cam,
For example, a surface treatment layer for reducing friction is formed on one of the inner peripheral surface of the roller and the outer peripheral surface of the shaft. As the surface treatment layer for reducing friction, for example, those belonging to the following (1) to (4) can be used. A reaction layer of a compound of sulfur and iron. A reaction layer of a compound of sulfur and iron containing nitrogen. Reaction layer of phosphate compound of phosphorus and iron. A treatment layer obtained by firing a simple substance or a mixture of molybdenum disulfide (MoS ₂ ) and polytetrafluoroethylene (PTFE) together with a thermosetting synthetic resin. A treatment layer obtained by firing a simple substance or a mixture of molybdenum disulfide and polytetrafluoroethylene together with a thermosetting synthetic resin on the surface of any of the above reaction layers. In the case of the tappet roller bearing of the present invention constructed as described above, the surface treatment layer for reducing friction immediately after the start of operation of the engine until the engine oil spreads to the tappet roller bearing portion. Even when the supply of engine oil cannot keep up with the speed of the engine or due to rapid acceleration / deceleration of the engine, lubrication between the parts that friction with each other can be ensured. Therefore, it is possible to prevent the surface of the component from being damaged. As a result, harmful irregularities are not formed on the surfaces of these components, and the lubrication state of the surfaces of these components can be made favorable fluid lubrication, thereby improving the durability of each component. EXAMPLES Experiments performed to confirm the effects of the present invention will be described. First, the first and second experiments will be described. These first and second experiments were performed using the life tester shown in FIG. A roller 6 is rotatably supported on the shaft 7 on an outer peripheral surface of an intermediate portion of the shaft 7 rotatably supported by the pair of bearings 17, 17. The shaft 7 is rotationally driven by an electric motor 8 by a belt 10 and a joint 11 stretched between a pair of pulleys 9a and 9b. With such a tester, a load was applied to the roller 6 in the radial direction, and the time required for the sliding portion between the inner peripheral surface of the roller 6 and the outer peripheral surface of the shaft 7 to reach the end of its life was measured. The experimental conditions are as follows. Outer diameter of the shaft 7: 10 mm Same material: SUJ2 (JIS G 4805,
High-carbon chromium bearing steel) Surface hardness: HRc61 Inner diameter of roller 6: 10.05 mm Same outer diameter: 30 mm Same width: 8 mm Same material: SUJ2 Same surface hardness: HRc61 Shaft 7 rotation speed: 3000 rpm Roller 6 Load applied to: 66 kgf The first and second experiments were performed under the above conditions. And in the case of the first experiment, the shaft 7
The test was performed in a non-lubricated (dry) state without supplying lubricating oil between the outer peripheral surface of the roller 6 and the inner peripheral surface of the roller 6. In the second experiment, 3 μl of engine oil (SE grade, 10 grade) was placed between the outer peripheral surface of the shaft 7 and the inner peripheral surface of the roller 6.
W-30) was supplied by a microsyringe, and a small amount of lubrication was established between these two peripheral surfaces. The life of the sliding part is
The time required for the temperature of the roller 6 to reach 160 ° C. or the time required for the current value of the electric motor 8 to reach the overcurrent value was determined to be the shorter of the two. The elapsed time up to durable life). Table 1 shows the results of the first experiment and Table 2 shows the results of the second experiment. [Table 1] [Table 2] In Tables 1 and 2 in which the results of the first and second experiments are described, those having the word “executed” at the beginning of the sample numbers are compared with the examples belonging to the present invention and compared with the examples of the present invention. Each of the comparative examples deviating from the present invention is indicated by the letters "." Samples having the same “A to Q” after the sample number are the same type of sample in the first experiment and the second experiment. And among the samples belonging to the present invention, A, B, C,
J, K, L belong to any of the above, D, M belong the same, E, F, G, N, O, P
Belongs to the same. In addition, the treated portion represents a portion where a surface treatment layer for reducing friction is formed, and the term “shaft” refers to a roller where the surface treatment layer is formed on the outer peripheral surface of the shaft 7. The fact that a surface treatment layer is formed on the inner peripheral surface of the roller 6 is shown. Further, the unit of the durability life is the total number of rotations. Considering the description in Table 1 showing the results of the first experiment, the following can be understood. (1) Each of the samples belonging to the present invention can obtain a durable life that is twice or more as long as the comparative example in which no surface treatment layer is formed. (2) Surface damage called smear occurred in all comparative examples, and A, B, and
J and K also occurred. (3) D and M belonging to the above, which are one embodiment of the present invention, have not only a long life but also no surface damage. (4) E, F, G, which belong to the above which is one embodiment of the present invention,
N, O, and P not only have a sufficiently long durable life but also do not cause surface damage. From these (1) to (4), it can be seen that, in the non-lubricated state (dry), the solid lubricant, molybdenum disulfide or polytetrafluoroethylene, has a large friction reducing effect due to the sliding contact surface. It can be understood that the effect of preventing surface damage due to the above is obtained. Particularly, a treatment layer obtained by firing a simple substance or a mixture of molybdenum disulfide and polytetrafluoroethylene together with a thermosetting synthetic resin on the surface of a reaction layer of a phosphate compound of manganese phosphate and iron ( E, N) show that the durable life is particularly long. still,
In the experiment, manganese phosphate was used to produce a phosphate by combining with iron, but the same effect can be obtained by using zinc phosphate. As is clear from the comparison of N, O, and P, even among the treated layers obtained by firing, a phosphate treatment that does not lower the surface hardness (manganese phosphate treatment in the experiment; the same applies to zinc phosphate treatment). ) Is preferable from the viewpoint of ensuring the durability life. In particular, as the thermosetting synthetic resin, a surface treatment layer using polyamideimide having high heat stability as a binder is particularly preferable. Further, as is clear from comparison between AG and JP, the surface on which the surface treatment layer for reducing friction is formed (if formed on only one of the surfaces). It is preferably the outer peripheral surface of the shaft 7, which is the surface on the side of movement. Therefore, when actually implementing the tappet roller bearing shown in FIGS. 1 and 2, it is preferable to form a surface treatment layer on the inner peripheral surface of the roller 6. Next, by considering the description in Table 2 showing the results of the second experiment performed in a small amount of lubrication, the following can be understood. (1) The durable life is longer than that in the non-lubricated state, and none of those belonging to the present invention causes surface damage. (2) A, B, and
C, J, K and L tended to have a longer durable life than D and M belonging to the same, except for B and K which are subjected to the sulfurizing treatment. That is, in the micro lubrication state, the reaction layer of iron and sulfur, nitrogen, phosphorus, etc., as described above, improves the friction reducing effect more than the solid lubricant fired film as described above. In particular, the shaft 7
The durability life of C obtained by subjecting the outer peripheral surface to the nitrosulfurizing treatment is longer than that of the other examples. (3) E, F, G, which belong to the above which is one embodiment of the present invention,
N, O, and P have sufficiently long durability life. Further, the description in Table 1 showing the test results in the non-lubricated state and the description in Table 2 showing the test results in the slight lubrication state are shown. By comparison, we can see the following. (1) In the non-lubricated state, the results of which are shown in Table 1, the solid lubricant fired film shown above is excellent in both the effects of improving the durability life and preventing surface damage, In a lubricated state, a reaction layer of a compound of iron and sulfur or a reaction layer of a compound of iron and a phosphate is effective in improving the durability life. (2) That is, the fired solid lubricant film has a great effect in a non-lubricated state until the engine oil is supplied. The effect can be obtained. (3) Therefore, according to the above-mentioned surface treatment layer in which the above-mentioned reaction layer is covered with the above-mentioned fired solid lubricant film, a sufficient effect can be obtained from immediately after the start of operation of the engine until a long time elapses. . Next, the results of a bench surface damage reproduction test assuming actual use conditions will be described. This reproduction test was performed using a surface damage tester as shown in FIG.
A ring 14 having an outer diameter of 20 mm is press-fitted into an intermediate portion of a shaft 13 driven to rotate by a pulley 12. The ring 14 corresponds to the cam 2 (FIGS. 1 and 2). The roller 6 pressing against the outer peripheral surface of the ring 14 has an inner diameter of 8.82.
mm, shaft 20 mm in outer diameter, 8 mm in width, and 8.8 mm in outer diameter
It is rotatably supported around. The material of the roller 6 and the shaft 5 is SUJ2 and the surface hardness is HRc62.
When a surface treatment for reducing friction was performed, the surface treatment was performed over the entire surface of the roller 6. At the time of the test, the shaft 13 was
While rotating the roller 6 at rpm, the roller 6
5 was pressed against the outer peripheral surface of the ring 14 via a steel ball 16 with a load of 100 kgf. Also, the lubrication between the inner peripheral surface of the roller 6 and the outer peripheral surface of the shaft 5 is non-lubricated, and the minimum between the outer peripheral surface of the roller 6 and the outer peripheral surface of the ring 14 is such that these two outer peripheral surfaces are not seized. Engine oil was dropped. Then, the time until the surface of the inner peripheral surface of the roller 6 is damaged and the temperature of the roller 6 rises abnormally or a remarkable vibration is generated, or the electric motor for driving the shaft 13 is driven. The time until the current value became the overcurrent value was determined as the endurance time. The results are shown in Table 3 below. [Table 3] In the Table 3, "Execution" is added at the beginning of the sample number.
Those with the letters of the examples are examples belonging to the present invention, those with the letters of "comparison" are comparative examples that deviate from the present invention,
Each is represented. The letters C, D, E, and H described after the sample numbers correspond to Tables 1 and 2 described above (the same symbols are applied to the same surface treatments). As is evident from the test results described in Table 3, the present invention contributes to the improvement of the durability in a non-lubricated state. Can be obtained. The surface treatment layer according to the present invention is formed not only on one or both of the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6, but also on one or both of the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6. You can do things. A tappet roller bearing in which a surface treatment layer is formed only on one or both of the outer peripheral surfaces of these two members 2 and 6 also prevents surface damage of these outer peripheral surfaces and improves durability life. Belongs to the range. Since the tappet roller bearing of the present invention is constructed and operates as described above, the tappet roller bearing not only prevents surface damage in the initial state of engine operation but also prevents seizure. The lubricating state thereafter is improved, and sufficient durability can be ensured.

[Brief description of the drawings] FIG. 1 is a partially cut plan view of a tappet roller bearing. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a schematic side view of a life tester. FIG. 4 is a vertical side view of the surface damage tester. [Explanation of symbols] 1 camshaft 2 cam 3 Rocker arm 4 Support wall 5 axes 6 rollers 7 Shaft 8 Electric motor 9a, 9b pulley 10 belt 11 Joint 12 pulley 13 shaft 14 Ring 15 Load lever 16 steel balls 17 Bearing 18 through hole

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[Procedure amendment] [Date of submission] April 22, 2003 (2003.4.2
2) [Procedure amendment 1] [Document name to be amended] Description [Item name to be amended] Full text [Amendment method] Change [Content of amendment] [Document name] Description [Title of invention] Tappet roller bearing [Claims] A cam fixed to a camshaft that rotates in synchronization with a crankshaft of an engine, and a pair of members provided opposed to the cam and receiving the movement of the cam and formed at an interval. A tappet roller bearing comprising a supporting wall portion, a shaft spanned between the pair of supporting wall portions, and a roller rotatably supported around the shaft. Along with the surface of at least one of the plurality of members relatively displaced with respect to the partner member,
Molybdenum disulfide is formed on the surface of the reaction layer of the phosphate compound of phosphorus and iron.
Thermal curing of mixtures of butene and polytetrafluoroethylene
Treatment layer obtained by baking with a synthetic resin
A tappet roller bearing having a spun surface treatment layer. Description: BACKGROUND OF THE INVENTION 1. Field of the Invention A tappet roller bearing according to the present invention is incorporated in a valve train of an engine to reduce the friction of the valve train so that it can be used during engine operation. It is intended to reduce the fuel consumption rate. 2. Description of the Related Art For the purpose of reducing friction inside an engine and reducing the combustion consumption rate, rotation of a camshaft synchronized with a crankshaft is converted into reciprocating motion of an intake valve and an exhaust valve. It is common practice to incorporate tappet roller bearings into the parts. 1 and 2 show the actual opening 3-1.
1 shows a tappet roller bearing described in JP 08806. A rocker arm 3 is provided opposite to a cam 2 fixed (generally, integrally formed) to a camshaft 1 which rotates in synchronization with the crankshaft of the engine and which receives the movement of the cam 2. Have been. At the end of the rocker arm 3, a pair of support walls 4, 4 are provided at an interval from each other. The pair of support walls 4, 4
A hollow or solid shaft 5 made of steel is bridged between them.
The ends of the shaft 5 are not quenched and are left raw. When the shaft 5 is fixed, the unquenched portion is
It is caulked toward the inner peripheral surfaces of the through holes 18 formed in the pair of support walls 4. As described above, the roller 6 is rotatably supported around the shaft 5 bridged between the pair of support walls 4, 4, and the outer peripheral surface of the roller 6 2 is in contact with the outer peripheral surface. According to the tappet roller bearing configured as described above, the frictional force acting between the rocker arm 3 and the cam 2 can be reduced, and the fuel consumption rate during engine operation can be reduced. Engine oil is supplied to the installation portion of such a tappet roller bearing during operation of the engine. The engine oil lubricates between the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6 and between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6. It is necessary that the camshaft 1 including the cam 2 is made of cast iron or bearing steel, and the roller 6 and the shaft 5 are made of high carbon chromium bearing steel. It is generally used from the viewpoint of reducing material costs and processing costs while ensuring strength.
Then, by devising the gap size and the surface roughness between the peripheral surfaces of the members, lubrication of the sliding contact portions between the members during operation of the engine is ensured. In order to ensure such lubrication, the shaft 5 is made of phosphor bronze and the roller 6 is made of high carbon chromium bearing steel. Also, it has been conventionally proposed to open an oil supply hole for supplying the engine oil to the rocker arm 3 and the shaft 5 as described in Japanese Utility Model Laid-Open No. 4-32210. Further, the roller 6 may be made of a ceramic such as silicon nitride.
No. 5296, Japanese Utility Model Application Laid-Open No. Sho 62-203911, Japanese Utility Model Application Laid-Open No. 3-108806, and the like.
It has been conventionally proposed. [0006] However, in the case of the above-described tappet roller bearing known in the related art, there are the following points to be solved. First, when the camshaft 1 including the cam 2 is made of cast iron or bearing steel and the shaft 5 and the roller 6 are made of high carbon chromium bearing steel, depending on the operating conditions,
One or both of the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6;
Further, surface damage called smear occurs on one or both of the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6. Such surface damage is caused by a non-lubricating condition of the contact portion between the outer peripheral surfaces of the two members 5 and 6 and the contact portion between the outer peripheral surfaces of the two members 2 and 6 during the assembly operation. And occur.
That is, a processing oil such as a cutting oil that adheres at the time of machining, and a rust-preventive oil for preventing corrosion during transportation are attached to the surfaces of these members 2, 5, and 6. . If these oils remain, lubrication between the outer peripheral surfaces is achieved immediately after the start of operation of the engine. However, in the engine assembly process in recent years, these oils have been washed away with a minimum necessary amount of washing oil in order to prevent deterioration of the engine oil due to mixing into the engine oil. For this reason, in the engine immediately after assembly, the contact portion between the two outer peripheral surfaces is in a state close to non-lubrication. When the engine is started from this state, the peripheral surfaces rub strongly against each other for a short period of time until the supply of the engine oil without any lubrication. As a result, the above-mentioned surface damage occurs on each of these peripheral surfaces. If the surface damage thus generated is remarkable, there is a possibility that the contact portion between the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6 is seized. Also, even when the surface damage is slight, minute projections are formed on each of the above-mentioned peripheral surfaces, and even after the supply of engine oil is performed by these projections, sliding between these peripheral surfaces can be performed. It becomes difficult for the lubrication state of the part to be completely fluid lubrication. As a result, when the surface fatigue of each peripheral surface portion increases with time, or when the oil film formation cannot follow a rapid speed fluctuation, such as when the engine is rapidly accelerated or decelerated,
Significant localized surface damage can occur. or,
Devising the surface roughness of the peripheral surface of each member 2, 5, 6 itself,
It is intended to make effective use of the supplied engine oil and does not help prevent surface damage in an unlubricated state. Further, if the outer peripheral surface of the phosphor bronze shaft 5 and the outer peripheral surface of the roller 6 made of high carbon chromium bearing steel are brought into contact, dissimilar metals come into contact with each other. I do. However, in this case, the material cost and the processing cost of the shaft 5 increase. In addition, the effect of preventing surface damage in an unlubricated state is insufficient. Further, if the roller 6 is made of a ceramic such as silicon nitride, the material cost and processing cost of the roller 6 increase.
Further, the ceramic roller 6 is not only easily broken than a metal roller, but also has a strong aggressiveness to the metal cam 2 and easily wears the outer peripheral surface of the cam 2 significantly. Furthermore,
Since the ceramic roller 6 has a smaller amount of thermal expansion than the metal shaft 5, the change in the gap between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the roller 6 due to the operation and stop of the engine increases. For this reason, when the temperature of the engine is low, problems such as generation of vibration at the support portion of the roller 6 are likely to occur. The tappet roller bearing of the present invention has been invented in order to solve any of these problems. The tappet roller bearing of the present invention has the same structure as the above-described conventional tappet roller bearing.
A cam fixed to a camshaft that rotates in synchronization with a crankshaft of the engine, and a pair of support wall portions provided opposite to the cam and formed with a space between members receiving the movement of the cam; The shaft comprises a shaft suspended between the pair of support walls, and a roller rotatably supported around the shaft. In particular, in the tappet roller bearing according to the present invention, the surface of at least one of a plurality of members relatively displaced with respect to a mating member with the rotation of the cam,
For example, a surface treatment layer for reducing friction is formed on one of the inner peripheral surface of the roller and the outer peripheral surface of the shaft. As the surface treatment layer for reducing friction, for example, those belonging to the following (1) to (4) can be considered . A reaction layer of a compound of sulfur and iron. A reaction layer of a compound of sulfur and iron containing nitrogen. Reaction layer of phosphate compound of phosphorus and iron. A treatment layer obtained by firing a simple substance or a mixture of molybdenum disulfide (MoS ₂ ) and polytetrafluoroethylene (PTFE) together with a thermosetting synthetic resin. A treatment layer obtained by firing a simple substance or a mixture of molybdenum disulfide and polytetrafluoroethylene together with a thermosetting synthetic resin on the surface of any of the above reaction layers. The present invention belongs to these, and particularly,
A layer obtained by superposing the above-mentioned treatment layers is referred to as the above-mentioned surface treatment layer.
ing. In the case of the tappet roller bearing of the present invention configured as described above, a table of the reaction layer of the phosphate compound of phosphorus and iron.
On the surface, molybdenum disulfide and polytetrafluoroethylene
By baking a mixture of
The surface treatment layer , which is formed by stacking treatment layers, reduces friction, immediately after the start of operation of the engine, until the engine oil spreads to the tappet roller bearings, or when the engine is suddenly accelerated or decelerated, the supply of engine oil is performed. Even if it cannot catch up, lubrication between parts that rub against each other can be ensured. Therefore, it is possible to prevent the surface of the component from being damaged. As a result, harmful irregularities are not formed on the surfaces of these components, and the lubrication state of the surfaces of these components can be made favorable fluid lubrication, thereby improving the durability of each component. EXAMPLES Experiments performed to confirm the effects of the present invention will be described. First, the first and second experiments will be described. These first and second experiments were performed using the life tester shown in FIG. A roller 6 is rotatably supported on the shaft 7 on an outer peripheral surface of an intermediate portion of the shaft 7 rotatably supported by the pair of bearings 17, 17. The shaft 7 is rotationally driven by an electric motor 8 by a belt 10 and a joint 11 stretched between a pair of pulleys 9a and 9b. With such a tester, a load was applied to the roller 6 in the radial direction, and the time required for the sliding portion between the inner peripheral surface of the roller 6 and the outer peripheral surface of the shaft 7 to reach the end of its life was measured. The experimental conditions are as follows. Outer diameter of the shaft 7: 10 mm Same material: SUJ2 (JIS G 4805,
High carbon chrome bearing steel) Same surface hardness: HRc61 Inner diameter of roller 6: 10.05 mm Same outer diameter: 30 mm Same width: 8 mm Same material: SUJ2 Same surface hardness: HRc61 Shaft 7 rotation speed: 3000 rpm Roller 6 Load applied to: 66 kgf The first and second experiments were performed under the above conditions. And in the case of the first experiment, the shaft 7
The test was performed in a non-lubricated (dry) state without supplying lubricating oil between the outer peripheral surface of the roller 6 and the inner peripheral surface of the roller 6. In the second experiment, 3 μl of engine oil (SE grade, 10 grade) was placed between the outer peripheral surface of the shaft 7 and the inner peripheral surface of the roller 6.
W-30) was supplied by a microsyringe, and a small amount of lubrication was established between these two peripheral surfaces. The life of the sliding part is
The time required for the temperature of the roller 6 to reach 160 ° C. or the time required for the current value of the electric motor 8 to reach the overcurrent value was determined to be the shorter of the two. The elapsed time up to durable life). Table 1 shows the results of the first experiment and Table 2 shows the results of the second experiment. [Table 1] [Table 2] In Tables 1 and 2 in which the results of the first and second experiments are described, those having the word “executed” at the beginning of the sample numbers are compared with the examples belonging to the present invention and compared with the examples of the present invention. Each of the comparative examples deviating from the present invention is indicated by the letters "." Samples having the same “A to Q” after the sample number are the same type of sample in the first experiment and the second experiment. And A, B, C, J, K, and L belong to any of the above, D and M belong to the same,
E, F, G, N, O, P belong to the same. In addition, the treated portion represents a portion where a surface treatment layer for reducing friction is formed, and the term “shaft” refers to a roller where the surface treatment layer is formed on the outer peripheral surface of the shaft 7. There is a fact that the surface treatment layer is formed on the inner peripheral surface of the roller 6,
Each is represented. Further, the unit of the durability life is the total number of rotations. Considering the description in Table 1 showing the results of the first experiment, the following can be understood. (1) Each of the samples having the surface treatment layer obtained has a durability that is at least twice as long as the comparative example in which the surface treatment layer is not formed. (2) The surface damage called smear occurred in all of the comparative examples, and also occurred in A, B, J, and K belonging to the above . (3) D and M belonging to the above not only have a long service life but also do not cause surface damage. (4) E, F, G, N, O, and P belonging to the above not only have a sufficiently long durable life but also do not cause surface damage. From these (1) to (4), it can be seen that in the non-lubricated state (dry), the solid lubricant, molybdenum disulfide or polytetrafluoroethylene, has a large friction reducing effect due to the sliding contact surface. It can be understood that the effect of preventing surface damage due to the above can be obtained. Particularly, an embodiment of the present invention, a treatment obtained by firing a mixture of molybdenum disulfide and polytetrafluoroethylene together with a thermosetting synthetic resin on the surface of a reaction layer of a phosphate compound of manganese phosphate and iron. It can be seen that the laminated layers (E, N) have a particularly long durable life. In the experiment, manganese phosphate was used to combine with iron to form a phosphate, but the same effect can be obtained by using zinc phosphate. As is apparent from a comparison of N, O, and P, even among the treated layers obtained by firing, a phosphate treatment that does not reduce the surface hardness (manganese phosphate treatment in the experiment; the same applies to zinc phosphate treatment). ) Is preferable from the viewpoint of ensuring the durability life. In particular, as the thermosetting synthetic resin, a surface treatment layer using polyamideimide having high heat stability as a binder is particularly preferable. Further, as is clear from comparison between AG and JP, the surface on which the surface treatment layer for reducing friction is formed (if formed on only one of the surfaces). It is preferably the outer peripheral surface of the shaft 7, which is the surface on the side of movement. Therefore, when actually implementing the tappet roller bearing shown in FIGS. 1 and 2, it is preferable to form a surface treatment layer on the inner peripheral surface of the roller 6. Next, by considering the description in Table 2 showing the results of the second experiment performed in a small amount of lubrication, the following can be understood. (1) endurance life is longer than that of the non-lubricated state, the table
No surface treatment layer has any surface damage. (2) A, B, C, J, K, and L belonging to the above-mentioned are D, M belonging to the same except for B and K which are subjected to the sulfurizing treatment.
Endurance life tended to be longer than that of. That is, in the micro lubrication state, the reaction layer of iron and sulfur, nitrogen, phosphorus, etc., as described above, improves the friction reducing effect more than the solid lubricant fired film as described above. In particular, the durability life of C obtained by subjecting the outer peripheral surface of the shaft 7 to the nitrosulphurizing treatment is longer than that of other examples. (3) E, F, G, N, O and P belonging to the above have a sufficiently long durable life . Further, comparing the description in Table 1 showing the test results in the unlubricated state with the description in Table 2 showing the test results in the slight lubrication state, the following can be seen. (1) In the non-lubricated state, the results of which are shown in Table 1, the solid lubricant fired film shown above is excellent in both the effects of improving the durability life and preventing surface damage, In a lubricated state, a reaction layer of a compound of iron and sulfur or a reaction layer of a compound of iron and a phosphate is effective in improving the durability life. (2) That is, the fired solid lubricant film has a great effect in a non-lubricated state until the engine oil is supplied. The effect can be obtained. (3) Therefore, according to the above-mentioned surface treatment layer in which the above-mentioned reaction layer is covered with the above-mentioned fired solid lubricant film, a sufficient effect can be obtained from immediately after the start of operation of the engine until a long time elapses. . Next, the results of a bench surface damage reproduction test assuming actual use conditions will be described. This reproduction test was performed using a surface damage tester as shown in FIG.
A ring 14 having an outer diameter of 20 mm is press-fitted into an intermediate portion of a shaft 13 driven to rotate by a pulley 12. The ring 14 corresponds to the cam 2 (FIGS. 1 and 2). The roller 6 pressing against the outer peripheral surface of the ring 14 has an inner diameter of 8.82.
mm, shaft 20 mm in outer diameter, 8 mm in width, and 8.8 mm in outer diameter
It is rotatably supported around. The material of the roller 6 and the shaft 5 is SUJ2 and the surface hardness is HRc62.
When a surface treatment for reducing friction was performed, the surface treatment was performed over the entire surface of the roller 6. At the time of the test, the shaft 13 was
While rotating the roller 6 at rpm, the roller 6
5 was pressed against the outer peripheral surface of the ring 14 via a steel ball 16 with a load of 100 kgf. Also, the lubrication between the inner peripheral surface of the roller 6 and the outer peripheral surface of the shaft 5 is non-lubricated, and the minimum between the outer peripheral surface of the roller 6 and the outer peripheral surface of the ring 14 is such that these two outer peripheral surfaces are not seized. Engine oil was dropped. Then, the time until the surface of the inner peripheral surface of the roller 6 is damaged and the temperature of the roller 6 rises abnormally or a remarkable vibration is generated, or the electric motor for driving the shaft 13 is driven. The time until the current value became the overcurrent value was determined as the endurance time. The results are shown in Table 3 below. [Table 3] In the Table 3, "Execution" is added at the beginning of the sample number.
Those with the letters of the examples are examples belonging to the present invention, those with the letters of "comparison" are comparative examples that deviate from the present invention,
Each is represented. The letters C, D, E, and H described after the sample numbers correspond to Tables 1 and 2 described above (the same symbols are applied to the same surface treatments). [0033] Example der of this is apparent from the test results in Table 3, is possible to form the surface treatment layer contributes to improve durability in a non-lubrication state, the present invention Among the
In the case where the surface treatment shown in E is performed, excellent effects can be obtained. Note that the surface treatment layer according to the present invention is
And the outer peripheral surface of the roller 6 may be formed on one or both of the outer peripheral surface of the cam 2 and the outer peripheral surface of the roller 6. A tappet roller bearing in which a surface treatment layer is formed only on one or both of the outer peripheral surfaces of these two members 2 and 6 also prevents surface damage of these outer peripheral surfaces and improves durability life. Belongs to the range. Since the tappet roller bearing of the present invention is constructed and operates as described above, the tappet roller bearing not only prevents surface damage in the initial state of engine operation but also prevents seizure. The lubricating state thereafter is improved, and sufficient durability can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cut plan view of a tappet roller bearing. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a schematic side view of a life tester. FIG. 4 is a vertical side view of the surface damage tester. [Description of Signs] 1 Camshaft 2 Cam 3 Rocker arm 4 Support wall 5 Shaft 6 Roller 7 Shaft 8 Electric motors 9a, 9b Pulley 10 Belt 11 Joint 12 Pulley 13 Shaft 14 Ring 15 Load lever 16 Steel ball 17 Bearing 18 Through hole

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Claims (1)

Claims: 1. A cam fixed to a camshaft that rotates in synchronization with a crankshaft of an engine, and a member provided opposite to the cam and receiving the movement of the cam is spaced apart from the cam. A tappet roller bearing comprising a pair of support wall portions formed as described above, a shaft bridged between the pair of support wall portions, and a roller rotatably supported around the shaft. On the surface of at least one of a plurality of members relatively displaced with respect to the mating member with the rotation of the cam,
A tappet roller bearing having a surface treatment layer for reducing friction.