JP6043667B2 - Rocker arm - Google Patents

Description

  The present invention relates to a rocker arm.

  The rocker arm disclosed in Patent Document 1 is formed by bending a metal plate, and a pair of opposite side walls, a first connection wall that connects one end in the length direction of both side walls, and the length of both side walls. A second connecting wall that connects the middle of the direction. A through hole is coaxially formed at the other longitudinal end of both side walls, and a roller is rotatably supported by a support shaft inserted through the through hole, and a cam is in contact with the roller. An adjustment screw that contacts the upper end of the valve is screwed onto the first connecting wall.

  Further, a U-shaped recess in side view is formed between the first and second connecting walls in the middle of the both side walls in the length direction so as to open upward. Furthermore, an arch portion having an inverted U-shape in side view that bridges the first and second connecting walls is bulged between both side walls. And the penetration hole which can penetrate a rocker shaft is divided and formed by both the recessed parts and the arch part. The insertion hole is configured to open in a circular shape when viewed from the side, and has an inner diameter slightly larger than the outer diameter of the rocker shaft. Such a rocker shaft is swung by a cam with the rocker shaft as a fulcrum, thereby opening and closing the valve.

Japanese Patent No. 4039936

  By the way, the rocker arm is usually subjected to quenching in order to improve wear resistance. In this case, processing is performed taking into account the amount of deformation during heat treatment, but the inner diameter of the insertion hole tends to be larger than the target value. As a result, there is a situation that the rocker shaft rattles in the length direction in the insertion hole, and it is difficult to ensure a stable arm ratio. On the other hand, when the correction process for correcting the inner diameter of the insertion hole is performed, there is a problem that it takes time and costs and the cost increases.

  The present invention has been completed based on the above circumstances, and provides a rocker arm that does not require strict dimensional control of a portion that receives a rocker shaft and that is improved in robustness against deformation during heat treatment. The purpose is to do.

The present invention is a rocker arm that swings around a rocker shaft and opens and closes a valve, and has an arc-shaped bearing portion that receives the load of the rocker shaft, and the radius of curvature of the bearing portion is the rocker shaft. And the center of curvature of the bearing portion is provided at a position different from the axis center of the rocker shaft, and the bearing portion is separated in the circumferential direction of the outer peripheral surface of the rocker shaft. A bottom wall and a pair of side walls rising from both sides of the bottom wall, and the bearing portion is formed to bend in the bottom wall, and the side wall includes the bearing in a side view. The other side receiving part that is continuous in the circumferential direction is opened, and the other side receiving part is arranged so that a gap is formed between the rocker shaft and the outer peripheral surface of the rocker shaft. ,Previous Characterized in place of sliding contact with the outer peripheral surface of the rocker shaft a load of the rocker shaft exclusively received while.

According to the above configuration, since it is not necessary to strictly correspond to the radius of curvature of the bearing portion with the outer diameter of the rocker shaft, dimensional management is facilitated and the deformation during heat treatment can be accommodated. On the other hand, even with such a relatively rough dimension setting, the bearing portion is in contact with two locations separated in the circumferential direction of the outer peripheral surface of the rocker shaft, thereby positioning the rocker shaft in the arm ratio direction with respect to the bearing portion. Therefore, a stable arm ratio can be ensured. Further, since the mating receiving part is also constructed with dimensional accuracy capable of forming a gap with the rocker arm, it does not require strict dimensional management and is easy to manufacture.

It is sectional drawing of the rocker arm of Example 1 of this invention. It is the sectional view on the AA line of FIG. It is an expanded view of a rocker arm. It is a general view which shows the use condition of a rocker arm. FIG. 6 is a development view of a rocker arm according to a second embodiment. FIG. 3 is a diagram corresponding to FIG. 2.

Preferred embodiments of the present invention are shown below .

Before the length direction end portion of the Kisokokabe comes into contact with the upper end of the valve, the length direction end portion of the bottom wall, which moves vertically in response to movement of the cam, to the two side walls An insertion hole through which the rocker shaft can be inserted is formed coaxially, and a hole edge of the insertion hole is defined by the bearing portion and the counterpart receiving portion, and the bearing portion is in the length direction of the bottom wall. It is curved in the middle. With this configuration, the rocker arm can be easily manufactured from a single plate.

<Example 1>
A first embodiment of the present invention will be described with reference to FIGS. The rocker arm 10 according to the first embodiment is supported by the rocker shaft 60 and is rocked by the cam 70 to open and close the valve 71.

  First, the overall structure of the internal combustion engine including the rocker arm 10 will be briefly described. In the following, a V-type engine is exemplified as the internal combustion engine, but of course, the present invention is not limited to this. FIG. 4 shows only one of the cylinder rows on one side.

  As shown in FIG. 4, a port portion 73 (intake port or exhaust port) is formed in the cylinder head 72, and a stem hole 74 communicates with the port portion 73. The stem hole 74 incorporates a valve 71 that can open and close the intake port of the port portion 73. The valve stem 75 of the valve 71 protrudes from the stem hole 74, and a valve spring 76 is attached to the protruding portion to urge the valve 71 in the valve closing direction.

  One end portion in the length direction of the rocker arm 10 is abutted and supported by the upper end of the valve stem 75, and the other end portion in the length direction of the rocker arm 10 is screwed to an adjustment screw 78 via a nut 77. The adjusting screw 78 is abutted and supported at the upper end of the push rod 79, and the abutting position with the push rod 79 can be adjusted by changing the screwing amount with the nut 77.

  The push rod 79 is disposed on the side of the cylinder block 80, and a hydraulic tappet and an adjustment screw (hereinafter referred to as a hydraulic tappet 83) are slidably inserted into a cylindrical holder 82 formed integrally with an outer holder plate 81. Has been. The upper end of the hydraulic tappet 83 is in contact with the lower end of the push rod 79, and the lower end of the hydraulic tappet 83 is in contact with the outer peripheral surface of the cam 70 provided on the cam shaft 84.

Next, the structure of the rocker arm 10 will be specifically described.
The rocker arm 10 includes an arm body 11 as shown in FIG. The arm body 11 is formed by punching a single metal plate into the shape shown in FIG. Specifically, the arm main body 11 has a U-shaped cross section and includes a strip-like bottom wall 12 extending in the length direction and a pair of side walls 13 rising from both side edges of the bottom wall 12.

  The bottom wall 12 of the first embodiment is configured with a substantially constant width over the entire length. In the middle of the bottom wall 12 in the length direction, a bearing portion 14 having a substantially U shape in side view for receiving the load of the rocker shaft 60 is formed. The bearing portion 14 has an arc-shaped bearing surface 15 that is formed by curving a substantially intermediate portion in the length direction of the bottom wall 12 downward and opened upward. At the lower end portion of the bearing portion 14, a rounded portion 16 that is a starting point of a bending operation is formed to bulge downward. It is possible to prevent stress concentration by the rounded portion 16.

  As shown in FIG. 1, the bearing surface 15 of the bearing portion 14 has curvature centers X21 and X22 at positions different from the axis center X1 of the rocker shaft 60. Specifically, the centers of curvature X21 and X22 of the bearing surface 15 are located obliquely above the axis center X1 of the rocker shaft 60. More specifically, of the bearing surface 15 of the bearing portion 14, the bearing surface 15 </ b> R located on one end side in the length direction across the rounded portion 16 is centered on the upper left side of the rocker shaft 60. The bearing surface 15 </ b> F that has X <b> 21 and is located on the other end side in the length direction across the rounded portion 16 has a center of curvature X <b> 22 on the upper right side of the rocker shaft 60 in the illustrated diagonal right side. Further, the bearing surface 15 (including both the shaft surfaces 15F and 15R) of the bearing portion 14 has a radius of curvature larger than the radius of the rocker shaft 60. Therefore, in addition to the lower half portion of the rocker shaft 60, a part of the upper half portion can be accommodated in the bearing portion 14. In addition, a shaft abutting portion 17 that can abut on two locations separated in the circumferential direction of the outer peripheral surface of the rocker shaft 60 is formed on the bearing surface 15 of the bearing portion 14. The shaft contact portion 17 is disposed at two locations in the length direction across the rounded portion 16 of the bearing surface 15 of the bearing portion 14, and has a width with respect to the outer peripheral surface of the rocker shaft 60 as the rocker arm 10 swings. The sliding contact with the direction in a substantially line contact state. Here, the arm body 11 is positioned in the length direction with respect to the rocker shaft 60 by the shaft contact portion 17. Note that the portion of the bearing surface 15 of the bearing portion 14 other than the shaft contact portion 17 is configured as a region that does not substantially contact the rocker shaft 60.

  Further, a through hole 18 into which the adjustment screw 78 can be inserted is formed at the other end portion in the length direction of the bottom wall 12, and a cylindrical boss portion 19 protrudes from an opening edge portion on the lower side of the through hole 18. Is formed. On the inner peripheral surface of the boss portion 19, a screw portion 21 that can be screwed into the adjustment screw 78 is formed. For this reason, the adjustment screw 78 is fixed to the arm body 11 by screwing the nut 77 into the tip end portion of the adjustment screw 78 screwed into the boss portion 19 from above. When the push rod 79 moves up and down by driving the cam 70, the adjustment screw 78 also moves up and down accordingly. In other words, the other end of the bottom wall 12 in the length direction also moves up and down.

  Further, a valve abutting portion 22 that can abut on the upper end of the valve stem 75 is gently curved downward at one end in the length direction of the bottom wall 12. Note that the bottom wall 12 is inclined slightly upward from the bearing portion 14 to the valve contact portion 22. Here, when the adjustment screw 78 rises, the rocker arm 10 swings with the rocker shaft 60 as a fulcrum, the valve contact portion 22 descends, and the valve 71 is pushed down against the spring force of the valve spring 76. The valve 71 is opened. On the other hand, when the adjusting screw 78 is lowered, the rocker arm 10 swings with the rocker shaft 60 as a fulcrum, the valve contact portion 22 is raised, the valve 71 is pulled up by the spring force of the valve spring 76, and the valve 71 is closed. It becomes a state.

  Both side walls 13 are formed in a range extending over the entire length of the arm main body 11, and are arranged to face each other substantially in parallel along the length direction. The distal end portion of the adjusting screw 78 and the nut 77 are covered with the other end in the length direction of the side walls 13 from both sides.

  Insertion holes 23 are formed in both side walls 13 so as to penetrate coaxially at the same position as the bearing portion 14 in the length direction (substantially intermediate portion in the length direction). As shown in FIG. 1, a mating receiving portion 24 that surrounds the outer periphery of the rocker shaft 60 together with the bearing portion 14 is formed at the hole edge of the insertion hole 23. The counterpart receiving portion 24 has a pair of opposing edges 25 rising from both ends in the length direction of the bearing portion 14 and both ends in the width direction, and an upper edge 26 along the length direction connecting the both facing edges 25. And it is set as the form opened to a lateral optic port type. The counterpart receiving portion 24 is not substantially in contact with the rocker shaft 60, and a clearance S is secured between the rocker shaft 60 and the outer peripheral surface thereof.

  Further, when the counterpart receiving portion 24 and the bearing portion 14 are continuous in the circumferential direction as viewed from the side, the insertion portion 27 having a non-circular side view through which the rocker shaft 60 can be inserted is formed. In this case, in the lower part of the insertion part 27, the bearing part 14 positioned in the gravitational direction of the rocker shaft 60 exclusively receives the load, so that the upper part of the outer periphery of the rocker shaft 60 and the counterpart receiving part 24 are formed in the upper part of the insertion part 27. A gap S formed between the two is allowed.

Next, the manufacturing procedure of the arm body 11 will be briefly described.
First, the blank material shown in FIG. 3 is manufactured by punching one metal plate. In the blank material, a pair of side walls 13 are formed on both sides in the width direction across the bottom wall 12, and an oblong insertion hole 23 that is elongated in the length direction is formed at a substantially intermediate portion in the length direction of the side walls 13. ing. Subsequently, burring is performed on the other end portion in the length direction of the bottom wall 12 to form the boss portion 19, and the screw portion 21 is threaded on the inner peripheral surface of the boss portion 19. Then, both side walls 13 are raised by bending along a broken line 28 shown by a dotted line in FIG. 3, and further, a substantially intermediate portion in the length direction of the bottom wall 12 is bent downward to form the bearing portion 14. Then, the insertion part 27 is formed between the side walls 13 and the bottom wall 12. Note that the side walls 13 and the bearing portions 14 may be formed at the same time. Further, after the formation of the insertion portion 27, conventionally, it was necessary to strictly center the portion corresponding to the insertion portion 27 with respect to the rocker shaft 60. However, in the case of Example 1, the insertion portion 27 and the rocker Since the respective centers of the shafts 60 are displaced, the centering of the insertion portion 27 with respect to the rocker shaft 60 is substantially unnecessary, and workability is greatly improved.

  Thereafter, the arm body 11 is subjected to heat treatment such as soft nitriding, carbonitriding, and carburizing in order to improve wear resistance. Although the diameter of the insertion portion 27 changes due to the heat treatment, in the case of Example 1, if the shaft contact portion 17 is secured at two locations of the bearing portion 14, the positioning with respect to the rocker shaft 60 can be achieved. Therefore, the allowable range with respect to the change in the diameter of the insertion portion 27 can be increased, and the robustness against heat treatment can be improved.

  As described above, according to the rocker arm 10 of the first embodiment, the radius of curvature of the bearing portion 14 is larger than the radius of the rocker shaft 60, and the centers of curvature X21 and X22 of the bearing portion 14 are the same as the axis center X1 of the rocker shaft 60. Are provided at different positions, whereby the bearing portion 14 has a shaft abutting portion 17 that abuts at two locations separated in the circumferential direction of the outer peripheral surface of the rocker shaft 60, and thus the rocker arm 10 is manufactured. At this time, it is not necessary to strictly correspond the curvature radius of the bearing portion 14 to the outer diameter of the rocker shaft 60. As a result, dimensional management becomes easy, and the amount of deformation during heat treatment can be flexibly handled. On the other hand, even if such relatively rough dimensions are set, if the shaft contact portion 17 is secured at two locations of the bearing portion 14, the direction of the arm ratio of the rocker shaft 60 relative to the bearing portion 14 (the length of the rocker arm 10). In this case, a predetermined arm ratio can be obtained.

<Example 2>
5 and 6 show a rocker arm 10A according to a second embodiment of the present invention. In the second embodiment, the bearing portion 14 </ b> A is formed wide so that the surface pressure of the bearing portion 14 </ b> A with respect to the rocker shaft 60 is reduced.

  In the case of the second embodiment, as shown in FIG. 6, the bearing portion 14 </ b> A is wider than other portions of the bottom wall 12. Is supposed to be located. As shown in FIG. 5, according to the developed shape, the insertion holes 23 of the side walls 13 are opened as gate-shaped slits, and both the insertion holes 23 are arranged symmetrically across the center in the width direction of the bottom wall 12. ing. Then, both side walls 13 are raised and formed along a fold line 28 passing between both ends of the slits of both insertion holes 23, so that a protruding piece 29 protruding into the slit remains on the bottom wall 12 side and the bearing portion 14A A wide part is formed.

  According to the second embodiment, since the surface pressure of the bearing portion 14A with respect to the rocker shaft 60 can be reduced, the durability of the bearing portion 14A can be improved. Further, the bearing portion 14A having a low surface pressure can be easily manufactured as in the first embodiment. Since the second embodiment has the same structure as that of the first embodiment except for the bearing portion 14A, the same reference numerals are given to the same portions as those of the first embodiment in the drawings.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following aspects are also included in the technical scope of the present invention.
(1) The roller may be pivotally supported at the other longitudinal end of the bottom wall, and the cam may be in contact with the roller.
(2) The side walls need only have at least the counterpart receiving portion, and need not be formed over the entire length of the arm body.
(3) Instead of the adjusting screw, a lash adjuster may be provided.
(4) Instead of the boss portion, a separate nut member may be fixed to the bottom wall by welding or the like.
(5) Of the bearing surfaces of the bearing portion, the bearing surfaces located on both sides in the length direction across the rounded portion may have the same center of curvature.

S ... Gap X1 ... Axis center X21, X22 ... Curve center 10, 10A ... Rocker arm 11 ... Arm body 12 ... Bottom wall 13 ... Side wall 14, 14A ... Bearing part 15 ... Bearing surface 17 ... Shaft contact part 23 ... Insertion hole 24 ... Counterpart receiving part 60 ... Rocker shaft 71 ... Valve

Claims (2)

A rocker arm that swings around a rocker shaft and opens and closes a valve,
An arc-shaped bearing portion that receives a load of the rocker shaft, a radius of curvature of the bearing portion is larger than a radius of the rocker shaft, and a center of curvature of the bearing portion is an axis center of the rocker shaft; Are provided at different positions, and the bearing portion comes into contact with two locations separated in the circumferential direction of the outer peripheral surface of the rocker shaft ,
A bottom wall and a pair of side walls rising from both sides of the bottom wall are provided, the bearing portion is formed in a curved shape in the bottom wall, and the side wall includes a counterpart receiving member that is continuous with the bearing portion in the circumferential direction in a side view. The bearing portion is exclusively receiving the load of the rocker shaft by disposing the counterpart receiving portion so that a gap is formed between the counterpart receiving portion and the outer peripheral surface of the rocker shaft. A rocker arm, wherein the rocker arm is in sliding contact with an outer peripheral surface of the rocker shaft . One end in the length direction of the bottom wall abuts on the upper end of the valve, and the other end in the length direction of the bottom wall moves up and down in accordance with the movement of the cam. An insertion hole through which the rocker shaft can be inserted is formed coaxially, and a hole edge of the insertion hole is defined by the bearing portion and the counterpart receiving portion, and the bearing portion is in the middle of the bottom wall in the length direction. The rocker arm according to claim 1, wherein the rocker arm is curved .

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