JP2008008182A - Tappet roller bearing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tappet roller bearing structure capable of smoothly rotating a roller and superior in wear resistance. <P>SOLUTION: The tappet roller bearing structure is provided with a support shaft 6 and a tappet roller bearing 11 including a cylindrical roller fitted to the support shaft 6. Radial gap δ between an outer circumference shurface of the support shaft 6 and an inner circumference surface 13 of the roller satisfies an inequality, δ≥25 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tappet roller bearing structure, and more particularly to a tappet roller bearing structure used for a movable valve mechanism of an internal combustion engine.

  Conventionally, in a movable valve mechanism of an internal combustion engine, for example, a tappet roller described in Japanese Patent Application Laid-Open No. 2004-257287 (Patent Document 1) is intended to reduce friction loss at a contact portion between a rocker arm and a cam. A bearing 101 is used.

  Referring to FIG. 5, a tappet roller bearing 101 described in Japanese Patent Application Laid-Open No. 2004-257287 (Patent Document 1) is a support shaft fixed to support walls 104 a and 104 b arranged at one end of a rocker arm 104. An inner diameter roller 102 rotatably supported around 105, and is supported rotatably around the inner diameter side roller 102 with respect to the inner diameter side roller 102. And an outer diameter side roller 103 to be contacted.

A radial gap between the support shaft 105 and the inner peripheral surface of the inner diameter side roller 102 (hereinafter referred to as “radial gap”), and an outer peripheral surface of the inner diameter side roller 102 and an inner peripheral surface of the outer diameter side roller 103. The amount of at least one of the radial gaps between and is regulated to a range of 5 μm or more and less than 20 μm. Thereby, an oil film having sufficient strength can be formed over the entire circumference between the support shaft 105 and the inner diameter side roller 102 and between the inner diameter side roller 102 and the outer diameter side roller 103, and engine oil can be formed in these gaps. It is described that the insoluble components in it can be prevented from entering.
JP 2004-257287 A

  However, in reality, it is difficult to supply a sufficient amount of lubricating oil between the support shaft 105 and the inner diameter side roller 102 and between the inner diameter side roller 102 and the outer diameter side roller 103 with the above gap amount. is there. Further, in the conventional tappet roller bearing 101, the gap between the supporting walls 104a and 104b and the end face in the axial direction of the tappet roller bearing 101 is generally as small as 0.1 mm or more and less than 0.3 mm, so that a further sufficient amount can be obtained. Lubricating oil supply is difficult.

  Furthermore, since the size of the insoluble component in the engine oil is as small as about 30 nm, the diameter between the support shaft 105 and the inner diameter side roller 102 and between the inner diameter side roller 102 and the diameter side roller 103 is large. Even when the directional gap amount is in the above range, intrusion of insoluble components cannot be prevented.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a tappet roller bearing structure in which a roller can rotate smoothly and has excellent wear resistance.

  The tappet roller bearing structure according to the present invention includes a shaft and a tappet roller bearing having a cylindrical inner diameter side roller fitted to the shaft. The radial clearance between the outer peripheral surface of the shaft and the inner peripheral surface of the inner diameter side roller is 25 μm or more.

  Preferably, the tappet roller bearing further has an outer diameter side roller fitted to the inner diameter side roller. And the radial clearance between the outer peripheral surface of an inner diameter side roller and the inner peripheral surface of an outer diameter side roller is 25 micrometers or more.

  By setting the radial gap between the outer peripheral surface of the shaft and the inner peripheral surface of the inner diameter side roller and between the outer peripheral surface of the inner diameter side roller and the inner peripheral surface of the outer diameter side roller to 25 μm or more, the tappet roller Lubricating oil required for the bearing can be supplied. Thereby, the tappet roller bearing excellent in wear resistance can be obtained.

More preferably, the diameter of the outer peripheral surface of the inner member is φa, the diameter of the inner peripheral surface of the outer member fitted to the inner member is φb, the contact length between the inner member and the outer member is l, and the tappet Assuming that the load applied to the roller bearing is f, the contact surface pressure between the shaft as the inner member and the inner diameter side roller as the outer member for the contact surface pressure P obtained by Equation 1 is P ₁ , and the inner diameter side roller as the inner member, the contact surface pressure between the outer diameter side roller as the outer member and _{P 2,} satisfy _{0.85 ≦ P 1 / P 2 ≦} 1.15.

As the above-described configuration, by taking the contact surface pressure P ₁ between the shaft and the inner diameter side roller, the balance between the contact surface pressure P ₂ between the inner diameter side roller and the outer diameter side roller, the inner diameter side roller And the outer diameter side roller can rotate smoothly.

The above relational expression of P ₁ and P ₂ defines the range of P ₁ when P ₂ is used as a reference, but if the above relational expression is modified and P ₁ is used as a reference, 0 .85 ≦ P ₂ / P ₁ ≦ 1.15. That is, when _one of P ₁ and P ₂ is used as a reference, the other is within a range of ± 15% of the reference value.

  According to the present invention, the lubricity is improved by increasing the radial gap, and a tappet roller bearing structure in which the inner diameter side roller and the outer diameter side roller can rotate smoothly by balancing the contact surface pressure is obtained. Can do.

  A tappet roller bearing structure according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 is a cross-sectional view of the tappet roller bearing structure, and FIG. 2 is a view showing the movable valve mechanism 1 incorporating the tappet roller bearing 11.

  First, referring to FIG. 2, a movable valve mechanism 1 such as an internal combustion engine of an automobile is connected to a rocker arm 2 swingably supported by a shaft 5 and one end of the rocker arm 2, and intake / exhaust gas inside the engine , A support shaft 6 disposed between a pair of left and right support walls 2a, 2b at the other end of the rocker arm 2, a tappet roller bearing 11 fitted to the support shaft 6, and a camshaft (not shown) ) And a cam 4 having an eccentric portion 4a.

  Next, referring to FIG. 1, the tappet roller bearing structure employed in the movable valve mechanism 1 having the above configuration includes a support shaft 6 fixed to the support walls 2 a and 2 b, an outer peripheral surface 12 that contacts the cam 4, and And a cylindrical tappet roller bearing 11 having an inner peripheral surface 13 fitted to the support shaft 6. Then, the radial gap δ between the support shaft 6 and the inner peripheral surface of the tappet roller 11 is set within a range of δ ≧ 25 μm. The “radial gap” in this specification refers to the maximum gap amount in a state where the tappet roller bearing 11 is unevenly distributed on one side (downward in FIG. 1).

  In the movable valve mechanism 1 configured as described above, the rotation of the crankshaft (not shown) of the internal combustion engine is transmitted to the camshaft (not shown) via a timing belt (not shown) to rotate the cam 4. When the eccentric portion 4 a of the cam 4 comes into contact with the tappet roller bearing 11, the rocker arm 2 swings about the shaft 5 and pushes down the valve 3. Thereby, supply / exhaust in the internal combustion engine can be performed. At this time, since the tappet roller bearing 11 rotates with the rotation of the cam 4, it is possible to reduce the friction loss at the contact portion between the tappet roller bearing 11 and the cam 4.

  Further, by setting the radial gap δ between the support shaft 6 and the inner peripheral surface of the tappet roller bearing 11 within the above range, the amount of lubricating oil flowing into the gap between the two increases. Thus, even when the distance σ between the support walls 2a and 2b and the axial end surface of the tappet roller bearing 11 facing the support walls 2a and 2b is 0.1 mm ≦ σ ≦ 0.3 mm, the support shaft A sufficient amount of lubricating oil can be supplied between 6 and the tappet roller bearing 11. As a result, a tappet roller bearing structure excellent in lubricity can be obtained.

  Next, a tappet roller bearing structure according to another embodiment of the present invention will be described with reference to FIG. Since the basic configuration is the same as that of the tappet roller bearing structure shown in FIG.

The tappet roller bearing structure includes a support shaft 24, an inner diameter side roller 22 fitted to the support shaft 24, and an outer diameter side roller 23 fitted to the inner diameter side roller 22 and having an outer peripheral surface abutting a cam (not shown). And a double roller type tappet roller bearing 21 provided. A radial gap δ ₁ between the support shaft 24 and the inner peripheral surface of the inner diameter side roller 22, and a radial gap δ ₂ between the outer peripheral surface of the inner diameter side roller 22 and the inner peripheral surface of the outer diameter side roller 23, Are set in the ranges of δ ₁ ≧ 25 μm and δ ₂ ≧ 25 μm, respectively.

As a result, the amount of lubricating oil flowing between the support shaft 24 and the inner diameter side roller 22 and between the inner diameter side roller 22 and the outer diameter side roller 23 increases, so that the tappet roller bearing structure with excellent lubricity is provided. Can be obtained. Note that δ ₁ and δ ₂ may be the same value (δ ₁ = δ ₂ ) or different values (δ ₁ ≠ δ ₂ ) as long as they are within the above range.

Furthermore, the contact surface pressure P ₁ between the support shaft 24 as the inner member and the inner diameter side roller 22 as the outer member generated by the intermittent load applied to the tappet roller bearing 21 from the cam (not shown), The contact surface pressure P ₂ between the inner diameter side roller 22 serving as the side member and the outer diameter side roller 23 serving as the outer member has a relationship of 0.85 ≦ P ₁ / P ₂ ≦ 1.15.

The contact surface pressures P ₁ and P ₂ are values calculated based on the Hertz theory. Specifically, the load applied from a cam (not shown) is F (N), and the support shaft. 24 has an outer diameter of φA (mm), an inner diameter of the inner roller 22 is φB (mm), an outer diameter of the inner roller 22 is φC (mm), and an inner diameter of the outer roller 23 is φD (mm). ), The outer diameter of the outer diameter side roller 23 is φE (mm), the effective contact length between the support shaft 6 and the inner peripheral surface of the inner diameter side roller 22 is L ₁ (mm), and the outer peripheral surface of the inner diameter side roller 22 is When the effective length with the inner peripheral surface of the outer diameter side roller 23 is L ₂ (mm), it can be obtained by the following equations.

As described above, the contact surface pressure P ₁ between the support shaft 24 and the inner diameter side roller 22, by taking the balance between the contact surface pressure P ₂ between the inner diameter side roller 22 and the outer diameter side roller 23 Even in an environment where an intermittent load is applied, the inner diameter side roller 22 and the outer diameter side roller 23 can rotate smoothly.

The above relational expression of P ₁ and P ₂ defines the range of P ₁ when P ₂ is used as a reference, but if the above relational expression is modified and P ₁ is used as a reference, 0 .85 × P ₁ ≦ P ₂ ≦ 1.15 × P ₁ That is, when _one of P ₁ and P ₂ is used as a reference, the other is within a range of ± 15% of the reference value.

  Next, a test for confirming the effect of the present invention was performed using a double roller type tappet roller bearing as shown in FIG. The contents of this effect confirmation test will be described with reference to FIG. 4 is a schematic diagram of an experimental device for the effect confirmation test, Table 1 shows the dimensions of the inner diameter side roller 32 used for the effect confirmation test, and Table 2 shows the dimensions of the outer diameter side roller 33 used for the effect confirmation test. Show.

  First, referring to FIG. 4, an experimental apparatus for this effect confirmation test is fitted to a support shaft 34, a fixing jig 35 for fixing the support shaft 34, and the support shaft 34. 1-No. No. 20 inner side roller 32 and No. 2 shown in Table 2. 21-No. Tappet roller bearing 31 combined with 40 outer diameter side rollers 33, drive roll 36 that contacts the outer peripheral surface of outer diameter side roller 33, and rotation sensor that detects the rotation of inner diameter side roller 32 and outer diameter side roller 33. 37, 38.

Next, referring to Table 1, the inner diameter side roller 32 has the outer diameter dimension φC fixed at 18 mm, and the inner diameter dimension φB is changed in increments of 0.1 mm from 12.01 mm to 12.20 mm. Also, 12 mm outer diameter .phi.A of the support shaft 34, since the fixed respectively the effective contact length _{L 1} of the support shaft 34 and the inner diameter roller 32 to 15 mm, calculated in radial clearance δ ₁ (= φB-φA ), The contact surface pressure P ₁ (calculated by Formula 2) is as shown in Table 1, respectively. The “effective contact length” refers to the length of the cylindrical portion excluding the lengths of the chamfered portions at both ends from the axial length of the inner peripheral surface of the inner diameter side roller 32.

Next, referring to Table 2, in the outer diameter side roller 33, the outer diameter dimension φE is fixed to 32 mm, and the inner diameter dimension φD is changed in increments of 0.1 mm from 18.01 mm to 18.20 mm. Further, since the outer diameter dimension φC of the inner diameter side roller 32 is fixed to 18 mm and the effective contact length L ₂ between the inner diameter side roller 32 and the outer diameter side roller 33 is fixed to 15 mm, the radial gap δ ₂ (= φD− Table 2 shows the contact surface pressure P ₂ (calculated by φC) and the formula (2).

  As a combination of the inner diameter side roller 32 and the outer diameter side roller 33, No. No. 5 (φB = 12.05 mm, φC = 18 mm). 21-No. No. 40 outer diameter side rollers 33 (Table 3), and No. 40 No. 37 on the outer diameter side roller 33. 1-No. The experiment was conducted using a total of 40 types of tappet roller bearings in which 20 inner diameter side rollers 32 were combined (Table 4).

  As test conditions, the rotational speed of the drive roll 36 is 500 rpm, the intermittent load applied to the tappet roller bearing 31 from the drive roll 36 is assumed to be an intermittent load with an actual cam, and the tappet roller is set to 0 to 5000 N, 16 Hz. The method of supplying the lubricating oil to the bearing 31 was a splash type.

According to this effect confirmation test, combinations of item numbers 8 to 15 in Table 3 (0.8679 ≦ P ₁ / P ₂ ≦ 1.1795) and combinations of item numbers 4 to 10 in Table 4 (0 .7321 ≦ P ₁ / P ₂ ≦ 1.1518), the inner diameter side roller 32 and the outer diameter side roller 33 were able to rotate smoothly. That is, it was confirmed that by setting 0.85 ≦ P ₁ / P ₂ ≦ 1.15, a tappet roller bearing structure in which the inner diameter side roller 32 and the outer diameter side roller 33 can rotate smoothly is obtained.

For the radial gaps δ ₁ and δ ₂ of 20 μm or less, the amount of lubricating oil supplied between the support shaft 34 and the inner diameter side roller 32 and between the inner diameter side roller 32 and the outer diameter side roller 33 is as follows. Was insufficient. That is, it was confirmed that a tappet roller bearing structure excellent in lubricity can be obtained by setting δ ₁ ≧ 25 μm and δ ₂ ≧ 25 μm.

In this study, it shows the effective contact length L ₁ of the support shaft 34 and the inner diameter side roller 32, an example effective contact with the length L ₂ is identical to the inner diameter side roller 32 and the outer diameter side roller 33 However, the value is not limited to this, and may be different from each other.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The present invention is advantageously used for a tappet roller bearing employed in a movable valve mechanism of an internal combustion engine.

It is sectional drawing of the tappet roller bearing structure which concerns on one Embodiment of this invention. It is a figure which shows the movable valve mechanism of the internal combustion engine for motor vehicles. It is sectional drawing of the tappet roller bearing structure which concerns on other embodiment of this invention. It is the schematic of the testing apparatus implemented in order to confirm the effect of this invention. It is sectional drawing of the conventional tappet roller bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable valve mechanism, 2,104 Rocker arm, 2a, 2b, 104a, 104b Support wall, 3 valve, 4,106 cam, 4a Eccentric part, 5, 24, 34, 105 Support shaft, 11, 21 31, 101 Tappet roller bearing, 12 outer peripheral surface, 13 inner peripheral surface, 22, 32, 102 inner diameter side roller, 23, 33, 103 outer diameter side roller, 35 fixing jig, 36 rotating roll, 37, 38 rotation sensor.

Claims (3)

The axis,
A tappet roller bearing having a cylindrical inner diameter side roller fitted to the shaft,
A tappet roller bearing structure, wherein a radial gap between an outer peripheral surface of the shaft and an inner peripheral surface of the inner diameter side roller is 25 μm or more. The tappet roller bearing further includes an outer diameter side roller fitted to the inner diameter side roller,
2. The tappet roller bearing structure according to claim 1, wherein a radial gap between an outer peripheral surface of the inner diameter side roller and an inner peripheral surface of the outer diameter side roller is 25 μm or more. The diameter of the outer peripheral surface of the inner member is φa, the diameter of the inner peripheral surface of the outer member fitted into the inner member is φb, the contact length between the inner member and the outer member is l, and the tappet roller If the load applied to the bearing is f,

For the contact surface pressure P determined by
The contact surface pressure between the shaft as the inner member and the inner diameter side roller as the outer member is P ₁ ,
Said inner diameter side roller as the inner member, the contact surface pressure between the outer diameter side roller as the outer member when the P _2,
0.85 ≦ P ₁ / P ₂ ≦ 1.15
The tappet roller bearing structure according to claim 2, wherein:

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