WO2020148943A1

WO2020148943A1 - Rocker arm

Info

Publication number: WO2020148943A1
Application number: PCT/JP2019/037216
Authority: WO
Inventors: 琢麻中川
Original assignee: 株式会社豊田自動織機
Priority date: 2019-01-15
Filing date: 2019-09-24
Publication date: 2020-07-23
Also published as: JP7059943B2; JP2020112115A

Abstract

A rocker arm (1) has a roller (30) that serves as a cam-follower supported on a housing (10) by a rotation shaft (20). The rotation shaft (20) has both ends (21a and 21b) that protrude from the housing (10) via a shaft hole (14) of the housing (10). Flange parts (22 and 23) that restrict movement of the rotation shaft (20) in a thrust direction with respect to the shaft hole (14) are formed at the both ends (21a and 21b), respectively. The flange parts (22 and 23) are provided with planes (22a and 23a) capable of being brought into surface-contact with respective outer surfaces (13a) of the housing (10), respectively. The rotation shaft (20) including the flange parts (22 and 23) is constituted by a plurality of components connected to each other. Connected portions of the plurality of components are portions other than portions penetrating the shaft hole (14) of the rotation shaft (20).

Description

Rocker arm

The present invention relates to a rocker arm used for a valve train of an internal combustion engine.

Generally, the rocker arm has a roller that serves as a cam follower and a housing that supports the roller. For example, the housing has a pair of axial holes that rotatably support each end of the roller. The roller rotates about the rotation axis. Hooking portions that restrain the movement of the rotating shaft in the thrust direction are formed at both ends of the roller (see Japanese Patent Laid-Open No. 2016-90006). As shown in FIG. 11, both ends of the roller protrude from the housing H and press the ends in the thrust direction. As a result, each end of the roller is deformed so as to project outward in the radial direction intersecting the axial direction, and the hooking portion F is formed. The hooking portion F is formed by a surface inclined with respect to the rotation axis of the rotation shaft S.

The rotation axis S rotates with the rotation of the roller. At that time, when the inclined surface of the hook portion F contacts the shaft hole end edge portion H1 of the housing H, the contact becomes a line contact. Therefore, the contact pressure becomes high, and seizure or wear may occur at the contact portion.

An object of the present disclosure is to provide a rocker arm that has a housing that supports a roller that serves as a cam follower, and that causes less seizure or wear at the contact portion between the rotation shaft of the roller and the housing.

According to one feature of the present disclosure, the rocker arm has a housing and a roller that is a cam follower supported by the housing by a rotating shaft. The housing includes a pair of outer surfaces that are arranged opposite to each other and each have an axial hole formed therein. The rotary shaft penetrates the pair of shaft holes and is rotatably supported by the housing. The roller is supported by the rotating shaft between the pair of outer surfaces of the housing. The rotary shaft has both ends protruding from the housing through the shaft hole. Flange portions for restricting the movement of the rotary shaft in the thrust direction with respect to the shaft hole are formed at both ends. Each flange portion is provided with a flat surface capable of making surface contact with each outer surface of the housing. The rotary shaft including the flange portion is composed of a plurality of parts coupled to each other. The connecting part of the plurality of parts is located at a part excluding the part penetrating the shaft hole of the rotating shaft.

The rocker arm of the present disclosure relates to both the inner fulcrum type and the outer fulcrum type. The inner fulcrum type has a fulcrum at the center of the housing, and the housing tilts about the fulcrum. The housing has a power point on one end side, and a cam follower is provided at the power point. The operating point is provided on the other end side of the housing, and the valve is connected to the operating point. The outer fulcrum type has a force point at the center of the housing. The housing has a fulcrum on one end side and an action point on the other end side. The plurality of parts forming the rotating shaft are joined by press fitting, screw fastening, bonding, welding, or the like.

　The rotary shaft that has a flange that can make surface contact with the outer surface of the housing is attached to the housing by passing through the shaft hole of the housing and then combining multiple parts that make up the rotary shaft. The flat surface of the flange portion is in contact with the outer surface of the housing. As a result, the contact area between the rotary shaft and the housing is wide, and is wider than that in the form of linear contact, for example. As a result, the pressure per unit area at the contact portion is reduced, and seizure or wear at the contact portion can be suppressed. The connecting part of the plurality of parts is located at a part excluding the part penetrating the shaft hole of the rotating shaft. Therefore, the part that penetrates the shaft hole of the rotary shaft is configured by only one part. As a result, it is possible to easily manage the amount of thermal expansion due to frictional heat at the site.

According to another feature of the present disclosure, the rotating shaft is pierced by each shaft hole with a gap with respect to the hole wall of each shaft hole. Therefore, the rotating shaft floats with respect to the hole wall of the shaft hole. Therefore, the rotary shaft can smoothly rotate with respect to the shaft hole, and the rotational resistance of the roller can be suppressed.

According to another feature of the present disclosure, the roller is supported with respect to the rotating shaft via a plurality of needle bearings. Therefore, the roller can smoothly rotate with respect to the rotating shaft, and the rotational resistance of the roller can be suppressed. Thus, power loss due to rotation of the camshaft can be suppressed. Since the rotating shaft rotates, the contact position between the outer peripheral surface of the rotating shaft and each needle bearing can be changed with the rotation of the rotating shaft. As a result, it is possible to suppress the formation of indentations on the outer peripheral surface of the rotating shaft due to the contact pressure generated when the contact position does not change.

According to another feature of the present disclosure, the flange portion is a member separate from the shaft body of the rotating shaft and is attached to the outer peripheral surface or the end surface of the shaft body. For example, the flange portion is attached to the shaft body by fitting the end portion of the rotary shaft into the hollow portion of the annular flange portion. Alternatively, the flange portion is attached to the shaft body by connecting the end face of the rotary shaft to the plate-shaped flange portion.

Therefore, the shaft body that is inserted into the shaft hole consists of only one part. Therefore, the shapes of the shaft body and the shaft hole, which are determined in consideration of the amount of thermal expansion, are easily determined.

According to another feature of the present disclosure, the rotating shaft includes a first shaft member including a part of the shaft body and one of the flange portions, and a first shaft member including the remaining part of the shaft body and another one of the flange portions. A biaxial member is provided. The first shaft member and the second shaft member are connected at a position between the pair of outer surfaces of the housing.

Therefore, the connecting portion between the first shaft member and the second shaft member is positioned so as to avoid the portion penetrating the shaft hole of the rotary shaft. In other words, the part that penetrates the shaft hole of the rotating shaft can be configured by only one part. Therefore, the shapes of the shaft body and the shaft hole, which are determined in consideration of the amount of thermal expansion, are easily determined.

FIG. 3 is a vertical cross-sectional view of a valve train mechanism portion of an internal combustion engine to which a rocker arm according to the first embodiment is applied. It is an enlarged front view of 1st Embodiment. FIG. 3 is an enlarged plan view of the first embodiment. FIG. 4 is an enlarged view taken along the line IV-IV of FIG. FIG. 5 is an enlarged cross-sectional view taken along the line VV of FIG. It is a partially expanded view of the bearing of FIG. It is sectional drawing corresponding to FIG. 5 which shows 2nd Embodiment. It is sectional drawing corresponding to FIG. 5 which shows 3rd Embodiment. It is sectional drawing corresponding to FIG. 4 which shows 4th Embodiment. It is sectional drawing corresponding to FIG. 4 which shows 5th Embodiment. It is a partially enlarged view of a prior art example.

As shown in FIG. 1, the rocker arm 1 is provided between the cam 4 and the intake valve 3. The cam 4 is rotated by a cam shaft (not shown). The rocker arm 1 converts the operation of the cam 4 into the opening/closing operation of the intake valve 3. The rocker arm 1 includes a roller 30 serving as a cam follower at the center of the housing 10. A swinging fulcrum 11 is provided at the first end of the housing 10 so as to cover the tip of the pivot 2 and to be swingably supported. At the second end of the housing 10, a valve contact portion 12 that contacts the base end of the intake valve 3 is provided. These are configured on the cylinder head 5. Here, a mechanism for opening and closing the intake valve 3 is shown, but a mechanism for an exhaust valve (not shown) is similarly configured.

As shown in FIGS. 2 and 3, a cavity 15 for housing the roller 30 is formed between both ends of the housing 10. The cavity 15 is defined by a pair of side walls 13 connecting the first end and the second end of the housing 10 and the left and right ends of the first end and the second end. The pair of side walls 13 oppose each other, and a shaft hole 14 is formed in each of the side walls 13 (see FIG. 5 ). The rotary shaft 20 serving as the shaft center of the roller 30 is rotatably inserted into the shaft hole 14. A shaft body (corresponding to the rotating shaft) 21 of the rotating shaft 20 is pierced with a play in the shaft hole 14 and is floatingly supported. Therefore, the rotary shaft 20 is rotatable with respect to the side wall 13.

As shown in FIG. 4, the roller 30 is configured to include a plurality of needle bearings 32 between the outer ring 31 and the rotary shaft 20. Therefore, the outer ring 31 of the roller 30 is influenced by the rotation of the cam 4 and rotates together. As a result, the sliding resistance with the cam 4 is suppressed. That is, the rotation resistance of the roller 30 can be suppressed, and the power loss due to the rotation of the camshaft can be suppressed.

The roller 30 constantly receives the pressing force of the cam 4, as shown by the arrow in FIG. Therefore, if the rotary shaft 20 does not rotate and the positional relationship between the needle bearing 32 and the rotary shaft 20 does not change, the indentation due to the contact of the needle bearing 32 with the surface of the rotary shaft 20 is indicated by a black dot in FIG. 21d is formed and the needle bearing 32 becomes difficult to roll. However, in the case of the present embodiment, since the rotary shaft 20 is rotatable with respect to the side wall 13 of the housing 10 as described above, it is difficult or impossible to make the indentations.

As shown in FIG. 5, the shaft body 21 of the rotary shaft 20 is supported in a floating manner with respect to the shaft hole 14 of the side wall 13. In order to maintain the support state of the shaft body 21 by the shaft hole 14,

flange portions

22 and 23 for restricting the movement of the shaft body 21 in the thrust direction are provided at both ends of the shaft body 21. As shown in FIGS. 2, 3, and 5, the

flange portions

22 and 23 are annular components that are separate members from the shaft body 21. The shaft body 21 and the

flange portions

22 and 23 are formed so that the end portions of the shaft body 21 can be fitted into the hollow portions of the

annular flange portions

22 and 23 as shown in FIG. That is, the coupling between the shaft body 21 and the

flange portions

22 and 23 is performed at the boundary between the two. Therefore, the shaft main body 21 is inserted into the center of the roller 30 inserted in the cavity 15 of the housing 10, and the

flange portions

22 and 23 are press-fitted into the both ends of the shaft main body 21 from the both outsides of the shaft main body 21. Unify. In this way, the roller 30 is rotatably supported by the housing 10. Thus, the outer peripheral surface 21c of the shaft body 21 and the

flange portions

22 and 23 contact each other.

As shown in FIG. 5, the outer side surface 13a of the side wall 13 of the housing 10 and the inner side surfaces (flat surfaces) 22a and 23a of the

flange portions

22 and 23 are arranged so as to face each other. Therefore, even if the outer side surface 13a of the side wall 13 and the inner side surfaces 22a and 23a of the

flange portions

22 and 23 come into contact with each other while the rotating shaft 20 is rotating, they are in surface contact with each other, unlike the line contact in the prior art. The contact pressure does not increase, and the occurrence of seizure or wear at the contact portion can be suppressed.

Further, the shaft main body 21 and the

flange portions

22 and 23 are coupled to each other at both ends of the shaft main body 21, and the portion penetrating the shaft hole 14 of the shaft main body 21 is composed of only one part. Therefore, even if the relevant portion of the shaft main body 21 expands due to frictional heat associated with rotation, it is easier to manage the amount of thermal expansion than in the case where a plurality of parts are involved. Therefore, since the management of the amount of thermal expansion does not go well, the outer peripheral surface 21c of the shaft main body 21 does not easily contact the inner peripheral surface of the shaft hole 14 or does not contact it. Thus, the problem that the rotational resistance of the shaft body 21 increases can be avoided.

FIG. 7 shows the second embodiment. As shown in FIG. 5, the rotary shaft 20 of the first embodiment is composed of three parts. On the other hand, the rotating shaft 40 of the second embodiment is composed of two parts as shown in FIG. There is no difference in the other configuration between the two, and the repetitive description of the same part will be omitted.

In the rotating shaft 40 according to the second embodiment, one of the

flange portions

42 and 44 provided at both ends of the shaft body 41 is integrally formed with the shaft body 41. The other flange portion 42 is joined to the end portion of the shaft body 41 by press fitting as in the case of the first embodiment. Therefore, according to the second embodiment, the number of parts constituting the rotary shaft 40 can be reduced, and the productivity can be improved.

FIG. 8 shows a third embodiment. As shown in FIG. 5, the rotary shaft 20 of the first embodiment is composed of three parts. On the other hand, the rotating shaft 45 of the third embodiment is composed of two parts as shown in FIG. Further, the coupling of the two parts is arranged in the middle of the shaft main body, that is, at a portion supporting the roller 30. There is no difference in the other configuration between the two, and the repetitive description of the same part will be omitted.

The rotary shaft 45 of the third embodiment is composed of two parts, a shaft main body female part (first shaft member) 25 and a shaft main body male part (second shaft member) 26. The shaft body female portion 25 and the shaft body male portion 26 are integrally provided with

flange portions

27 and 28, respectively. The shaft main body female portion 25 has a recessed portion 25a at the axial center position in the portion supporting the roller 30. The shaft main body male portion 26 has a convex portion 26 a at the axial center position in the portion supporting the roller 30. By fitting the convex portion 26a into the concave portion 25a, the shaft body female portion 25 and the shaft body male portion 26 are coupled.

As shown in FIG. 8, when the rocker arm 1 is assembled, first, the roller 30 is installed between the pair of side walls 13. In this state, the shaft body female portion 25 is inserted into the shaft hole 14 from the outside of the shaft hole 14 of the one side wall 13. The shaft main body male portion 26 is inserted into the shaft hole 14 from the outside of the shaft hole 14 of the other side wall 13. The convex portion 26a is press-fitted into the concave portion 25a to engage the shaft body female portion 25 and the shaft body male portion 26. As a result, the roller 30 is supported by the rotating shaft 45 with respect to the housing 10. According to this configuration, the rocker arm 1 is assembled by connecting the two parts of the shaft body female portion 25 and the shaft body male portion 26. Therefore, the productivity of the rocker arm 1 can be improved. As the coupling structure of the shaft main body female part 25 and the shaft main body male part 26, various structures can be adopted in addition to the above structure.

FIG. 9 shows a fourth embodiment. As shown in FIG. 4, the rocker arm 1 of the first embodiment has a roller 30 including a needle bearing. On the other hand, the rocker arm 1 of the fourth embodiment has a double roller type roller 35. There is no difference in the other configuration between the two, and the repetitive description of the same part will be omitted.

As shown in FIG. 9, the roller 35 is composed of an outer ring 33 and an inner ring 34. Grease is applied between the inner peripheral surface of the outer ring 33 and the outer peripheral surface of the inner ring 34, and between the inner peripheral surface of the inner ring 34 and the outer peripheral surface of the shaft body 21. As a result, the outer ring 33 can smoothly rotate with respect to the inner ring 34, and the inner ring 34 can smoothly rotate with respect to the shaft body 21. Thus, the outer ring 33 is rotated smoothly following the rotation of the cam 4. The rest of the configuration is the same as that of the first embodiment, and a repeated description will be omitted.

FIG. 10 shows a fifth embodiment. As shown in FIG. 5, the rotary shaft 20 of the first embodiment has a shaft body 21 and

annular flange portions

22 and 23. The shaft main body 21 and the

flange portions

22 and 23 are connected so that the outer peripheral surfaces 21c of the respective end portions of the shaft main body 21 come into contact with the inner peripheral surfaces of the

flange portions

22 and 23. On the other hand, the rotating shaft 46 shown in FIG. 10 has a cylindrical shaft body 47 and disk-shaped

flange portions

48 and 49. The inner surface of the flange portion 48 is attached to the one end surface 47a of the shaft body 47 with an adhesive or the like. The inner surface of the flange portion 49 is attached to the other end surface 47b of the shaft body 47 with an adhesive or the like.

The specific embodiments have been described above, but the present invention is not limited to those appearances and configurations, and various changes, additions, and deletions are possible. For example, the rotating shaft described above is rotatably supported in the shaft hole of the housing. That is, the rotary shaft is floatingly supported with respect to the housing with a gap between the rotary shaft and the shaft hole. Instead of this configuration, a member that reduces frictional resistance between the rotating shaft and the shaft hole may be interposed between the rotating shaft and the shaft hole to facilitate rotation of the rotating shaft relative to the shaft hole.

Claims

It’s a rocker arm,
A housing provided with a pair of outer surfaces that are arranged to face each other and each have an axial hole formed therein;
A rotary shaft that penetrates through the pair of shaft holes and is rotatably supported by the housing;
A roller that is a cam follower supported between the pair of outer surfaces of the housing by the rotating shaft,
The rotating shaft has both end portions protruding from the housing through the shaft hole, and a flange portion for restraining movement of the rotating shaft in the thrust direction with respect to the shaft hole is formed at each of the both end portions,
Each of the flange portions includes a flat surface capable of making surface contact with each of the outer side surfaces of the housing,
The rotating shaft including the flange portion is composed of a plurality of parts coupled to each other,
A rocker arm in which a connecting portion of the plurality of components is located at a portion excluding a portion that penetrates the shaft hole of the rotating shaft.
The rocker arm according to claim 1,
The rotation shaft is a rocker arm that penetrates through the shaft holes with a gap between the shaft walls of the shaft holes.
The rocker arm according to claim 1 or 2,
The roller is a rocker arm supported by a plurality of needle bearings with respect to the rotation shaft.
The rocker arm according to any one of claims 1 to 3,
The flange portion is a rocker arm that is a member separate from the shaft body of the rotating shaft and is attached to an outer peripheral surface or an end surface of the shaft body.
The rocker arm according to any one of claims 1 to 3,
The rotating shaft includes a first shaft member including a part of a shaft body and one of the flange portions, and a second shaft member including a remaining part of the shaft body and another one of the flange portions. ,
A rocker arm in which the first shaft member and the second shaft member are connected at a position between the pair of outer surfaces of the housing.
The rocker arm according to any one of claims 1 to 5,
The roller is a rocker arm that is located between the pair of outer surfaces of the housing and is supported by the rotating shaft.