JP2008057514A - Cam follower device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of reducing the number of parts composing a valve train of an engine where the number of at least either the intake valves or the exhaust valves installed in one cylinder is two or more. <P>SOLUTION: A cam follower device is composed of: a pair of plate-like rocker arms 14, 14 disposed in parallel with each other, and connected to each other by at least one connection part 17 so as not to be relatively displaced; a support shaft 7a having both ends fixedly press-fitted into support holes 8a, 8a formed at one-side ends of both the rocker arms 17, 17; and a tappet roller 9 supported rotatably around an intermediate part of the support shaft 7a. With the cam follower device assembled in a valve train, the rotational motion of a cam 2 fixed to a camshaft is transmitted by the tappet roller 9 and the pair of rocker arms 14, 14 to valve elements 12, 12 which are two intake valves (or exhaust valves), and the two valve elements 12, 12 are reciprocated in the axial direction. By employing such a structure, the problem can be solved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The cam follower device according to the present invention is, for example, a three-valve engine, a four-valve engine, a five-valve engine, or the like in an engine in which at least one of a supply valve and an exhaust valve provided in one cylinder is two or more. It is incorporated in the valve mechanism and used to convert the rotation of the camshaft into the reciprocating motion of two air supply valves or two exhaust valves.

  The reciprocating engine (reciprocating piston engine) is provided with an intake valve and an exhaust valve that open and close in synchronization with the rotation of the crankshaft except for some two-cycle engines. In such a reciprocating engine, the movement of the camshaft that rotates in synchronization with the rotation of the crankshaft (in the case of a four-cycle engine, at half the rotational speed) is caused to move the intake valve and the exhaust valve by the rocker arm. The intake valve and the exhaust valve are reciprocated in the axial direction. In order to reduce friction inside the engine and reduce the fuel consumption rate, a tappet roller is generally incorporated between the camshaft and the rocker arm.

  8 to 9 show a first example of a conventional structure of a cam follower device including such a rocker arm and a tappet roller, which is described in Patent Document 1. FIG. A rocker arm 3 constituting the cam follower device is provided at a portion facing the cam 2 fixed to the camshaft 1 that rotates in synchronization with the crankshaft of the engine. A rocker shaft 5, which is a fixed shaft provided in parallel with the camshaft 1, is inserted into the through hole 4 formed in the intermediate portion of the rocker arm 3. As a result, the rocker arm 3 can be oscillated and displaced about the rocker shaft 5. Further, at one end portion (right end portion in FIG. 8) of the rocker arm 3, a pair of support wall portions 6 and 6 parallel to each other are provided as shown in detail in FIG. At the same time, the support shaft 7 is fixed in a state where it is stretched over both the support wall portions 6 and 6. For this purpose, both end portions of the support shaft 7 are fitted and fixed in a pair of support holes 8 and 8 formed at positions where the both support wall portions 6 and 6 are aligned with each other. Further, a tappet roller 9 is rotatably supported around a middle portion of the support shaft 7 via a radial needle bearing 10. The outer peripheral surface of the tappet roller 9 is brought into contact with the outer peripheral surface of the cam 2. Further, a screw hole (not shown) is provided at the other end portion (left end portion in FIG. 8) of the rocker arm 3, and an adjustment screw 11 is screwed and fixed to the screw hole. And the front-end | tip part (pressing part) of this adjustment screw 11 is abutted on the base end surface of the valve body 12 which is an air supply valve or an exhaust valve.

  During the operation of the engine, the rocker arm 3 swings and displaces with the rocker shaft 5 as a center (fulcrum) as the cam 2 rotates, and the valve body 12 is pushed by the pressing force of the adjusting screw 11 and the return spring. It is reciprocated in the axial direction by 13 elasticity. At this time, since the friction force acting between the cam 2 and the rocker arm 3 can be reduced by the tappet roller 9, the fuel consumption rate during engine operation can be reduced.

  In the case of the above-described conventional structure, as a method of internally fitting and fixing the both end portions of the support shaft 7 to the support holes 8 and 8 formed in the pair of support wall portions 6 and 6, It is conceivable to employ a method of press-fitting both end portions of the support shaft 7. However, in the case of the above-described conventional structure, both the support wall portions 6 and 6 are integrally formed with the rocker arm 3, and the interval between the both support wall portions 6 and 6 cannot be increased. For this reason, when both ends of the support shaft 7 are press-fitted into the both support holes 8, 8, the intermediate portion of the support shaft 7 is press-fitted into one of the support holes 8 in the process. It is necessary to pass through one of the support holes 8. As a result, the outer peripheral surface of the intermediate portion of the support shaft 7 may be damaged. On the other hand, the outer peripheral surface of the intermediate portion of the support shaft 7 serves as an inner ring raceway (or an inner sliding surface of the sliding bearing) of the radial needle bearing 10 that rotatably supports the tappet roller 9. It is not preferable to be scratched. Therefore, in order to prevent such problems from occurring, conventionally, only the outer peripheral surface of the intermediate portion of the support shaft 7 is hardened by induction hardening, and then both end portions of the support shaft 7 are connected to the both support holes 8, A fixing method in which the outer peripheral edge portions of both end surfaces of the support shaft 7 are caulked toward the opening peripheral edge portions of the support holes 8 and 8 in a state in which the inner periphery of the support shaft 7 is fitted with no looseness without looseness. Is adopted. However, such a fixing method has a large number of steps and causes an increase in cost.

  By the way, when only the conventional cam follower device as described above is used as the cam follower device incorporated in the valve operating mechanism when the valve operating mechanism of the engine is configured, the same number of cams 2 and tappet rollers as the valve bodies 12 are used. 9 is required. However, with the recent increase in the number of valves in the engine, the number of air supply valves and exhaust valves provided in one cylinder tends to increase to 2, 3, respectively, mainly in high performance engines. For this reason, in the case of configuring the valve operating mechanism of an engine having such multiple valves, if only the conventional cam follower device as described above is used, the number of parts of the valve operating mechanism becomes too large. Inconveniences such as increase in size, weight, friction, and cost are likely to occur.

JP 2004-1000049 A

  The cam follower device of the present invention was invented to realize a structure that can reduce the number of cams and tappet rollers to be used when configuring a valve operating mechanism of a multi-valve engine in view of the circumstances as described above. is there.

The cam follower device according to the present invention is, for example, a three-valve engine, a four-valve engine, a five-valve engine, and the like that operates an engine in which at least one of a supply valve and an exhaust valve provided in one cylinder is two or more. Used by incorporating into the valve mechanism. Such a cam follower device of the present invention includes a pair of plate-like rocker arms, a pair of support holes, a support shaft, a tappet roller, and a pair of pressing portions.
Of these, the pair of rocker arms are arranged in parallel with each other at a predetermined interval (at the same pitch as the pitch of the two valve bodies to be opened and closed simultaneously), and at least one connecting portion is Displacement is coupled impossible.
Further, the pair of support holes are formed concentrically with each other at positions where they are aligned with each other at one end portion or an intermediate portion of the both rocker arms.
Moreover, the said support shaft is being fixed in the state spanned between both said rocker arms by fitting the both ends into the said both support holes.
The tappet roller is rotatably supported around the intermediate portion of the support shaft.
Further, the pair of pressing portions are provided directly or via another member at the other end portions of the rocker arms.
And in the state incorporated in the valve operating mechanism, the outer peripheral surface of the tappet roller is brought into contact with the outer peripheral surface of the cam fixed to the camshaft, and each pressing portion is connected to two air supply valves or 2 One exhaust valve is abutted against the base end face of each exhaust valve.

In the cam follower device according to claim 2, the pair of support holes are formed concentrically with each other at one end of the pair of rocker arms, and at the intermediate portion between the two rocker arms. A pair of through holes are formed concentrically with each other at the matching positions. Then, in a state of being incorporated in the valve operating mechanism, a rocker shaft, which is a fixed shaft provided in parallel with the cam shaft, is inserted into these through holes, and the rocker arms swinging around the rocker shaft are centered. Enables dynamic displacement.
In the cam follower device according to the third aspect, the rocker arms are formed in the same shape and the same size by punching and bending one metal plate.

  Using the cam follower device of the present invention configured as described above, a valve operating mechanism for an engine in which at least one of an air supply valve and an exhaust valve provided in one cylinder is two or more is configured. For example, two intake valves or two exhaust valves can be opened and closed simultaneously by providing only one cam and tappet roller. Therefore, the number of parts of the valve mechanism can be reduced as compared with the case where only the conventional cam follower device as described above is used as the cam follower device incorporated in the valve mechanism. Accordingly, the valve mechanism can be reduced in size (space saving), reduced in weight, reduced in friction, reduced in cost, and the like.

  In the case of the cam follower device of the present invention, a method of press-fitting both end portions of the support shaft into these support holes can be adopted as a method of fitting and fixing both end portions of the support shaft into the pair of support holes. Even when this method is employed, the outer peripheral surface of the intermediate portion of the support shaft {the inner ring raceway of the radial needle bearing (or the inner sliding surface of the sliding bearing) for rotatably supporting the tappet roller} is damaged. You can prevent things. The reason for this is that, in the case of the present invention, the pair of rocker arms, in which the pair of support holes are formed concentrically with each other, are arranged in parallel with each other and cannot be relatively displaced by at least one continuous portion. However, since the distance between the portion where the both support holes are formed and the connecting portion can be made relatively large and the distance between the rocker arms can be widened, This is because the both end portions can be press-fitted into the inside of the both support holes through the openings on the opposite sides of the both support holes. In other words, in the case of the present invention, unlike the case of each of the conventional structures described above, in the process of press-fitting both ends of the support shaft into a pair of support holes, the intermediate portion of the support shaft is set to one of the support holes. This is because it is not necessary to perform the operation of passing the support shaft through one of the support holes in a state where the support shaft is press-fitted into (inserted by an interference fit). Further, when assembling the cam follower device of the present invention, if the method of press-fitting both ends of the support shaft into a pair of support holes (internally fitting by interference fit) as described above, both ends of the support shaft are Since it is not necessary to caulk and spread, it is not necessary to leave both ends of the support shaft in a raw state (a state in which no curing treatment is applied). Therefore, quenching of the support shaft can be performed by so-called submerged heating in which the entire support shaft is heated and then immersed in oil for quenching. Since the quenching process by sub-firing can be performed at a lower cost than the induction hardening process, the manufacturing cost can be reduced accordingly.

Further, in the case of the cam follower device of the present invention, since both the rocker arms are coupled so as not to be relatively displaceable by at least one continuous portion, it has been conventionally performed when the cam follower device is assembled to the engine. Phase adjustment work is not necessary.
Further, in the case of the cam follower device of the present invention, as long as both the rocker arms are formed in the same shape and the same size, the positional relationship between these rocker arms is made appropriate, and the contact state with a counterpart component such as a valve. It is possible to effectively prevent a difference from occurring.

[First example of embodiment]
FIGS. 1-5 has shown the 1st example of embodiment of this invention corresponding to Claims 1-3. The cam follower device of this example is, for example, an engine (OHC) in which at least one of a supply valve and an exhaust valve provided in one cylinder is two or more, such as a three-valve engine, a four-valve engine, and a five-valve engine. It is used by being incorporated in a valve mechanism of a type or DOHC type. Such a cam follower device of this example includes a pair of plate-like rocker arms 14, 14 having the same shape and the same size, one support shaft 7a, and one tappet roller 9.

  Among these, the pair of plate-like rocker arms 14 and 14 are arranged in parallel with each other at a predetermined interval (at the same pitch as the pitch of the pair of valve bodies 12 and 12), and at least one connecting portion. 17 is coupled so that relative displacement is impossible. Further, the support shaft 7a is fixed in a state where it is suspended between one end portions (the right end portions in FIGS. 1 and 2) of both the rocker arms 14 and 14. For this purpose, a pair of support holes 8a and 8a are formed concentrically with each other at positions where one end portions of the rocker arms 14 and 14 are aligned with each other. Then, after hardening the entire surface of the support shaft 7a by quenching, the distance between the rocker arms 14 and 14 is widened so that both ends of the support shaft 7a are connected to the support holes 8a and 8a. The support holes 8a and 8a are press-fitted through the openings on the sides facing each other. In addition, in order to widen the space | interval of both said rocker arms 14 and 14, the angle of the continuous part of these both rocker arms 14 and 14 and the said connection part 17 is enlarged (it is a magnitude | size exceeding 90 degree | times). In the case of this example, the connecting portion 17 prevents the rocker arms 14 and 14 from swinging relatively around the support shaft 7a. Further, the tappet roller 9 is rotatably supported via a radial needle bearing 10 on the outer peripheral surface of the intermediate portion of the support shaft 7a. Further, a pair of through holes 4, 4 are formed concentrically with each other at a position where they are aligned with each other at the intermediate portion between the rocker arms 14, 14. Moreover, a pair of convex parts 15 and 15 (pressing part) are provided in the lower surface of the other end part (left-end part of FIGS. 1-2) of both the rocker arms 14 and 14. FIG. The front end surfaces of both the convex portions 15 and 15 are partial cylindrical surfaces.

  The rocker arms 14 and 14 as described above are manufactured as follows. First, as shown in FIG. 5 (a), a pair of plates having the same shape and the same size are integrated by at least one continuous portion 17 by punching a single plate-like metal. Shaped rocker arms 14, 14 are formed. Thereafter, until both the pair of rocker arms are parallel to each other, both end portions of the connecting portion 17 are bent 90 degrees each other and arranged parallel to each other at a predetermined interval as shown in FIG. A pair of plate-like rocker arms are formed, which are coupled to each other so that relative displacement is impossible. In the process of bending, both end portions of the support shaft 7a provided with the tappet roller 9 around the intermediate portion can be fitted into the support holes 14a and 14a.

  In the state where the rocker arms 14 and 14 as described above are assembled to the valve operating mechanism of the engine, as shown in FIGS. The rocker arms 14 and 14 can be swung and displaced with the rocker shaft 5 as the center by inserting the rocker shafts 5 without shaking. At the same time, the outer peripheral surface of the tappet roller 9 is brought into contact with the outer peripheral surface of the cam 2 fixed to the camshaft 1, and the tip surfaces of the both convex portions 15, 15 are connected to the two valve bodies 12, 12 (one of the two intake valves or two exhaust valves provided in the same cylinder) abut one by one. When the engine is operated, the rocker arms 14 and 14 are oscillated and displaced in synchronization with each other about the rocker shaft 5 as the cam 2 rotates, and the two valve bodies 12 and 12 are It is reciprocated in the axial direction by the pressing force of both convex portions 15 and 15 and the elasticity of the return spring 13 (not shown, see FIG. 8).

  As described above, if the cam follower device of this example is used, the two valve bodies 12 and 12 can be reciprocated simultaneously only by providing one set of the cam 2 and the tappet roller 9. For this reason, as compared with the case where only the conventional cam follower device as described above is used as the cam follower device incorporated in the valve operating mechanism (independent cam follower device is incorporated for each valve body), the number of parts of the valve operating mechanism is reduced. Can be reduced. Accordingly, the valve mechanism can be reduced in size (space saving), reduced in weight, reduced in friction, reduced in cost, and the like. In the case of this example, by increasing the angle of the bent portion with the connecting portion 17, it is possible to widen the distance between the rocker arms 14, 14. Both ends of the support shaft 7a can be press-fitted into the pair of support holes 8a and 8a without damaging the outer peripheral surface of the intermediate portion. For this reason, as a method of curing the surface of the support shaft 7a, it is possible to employ a submerged quenching that can be carried out at a lower cost than the induction quenching. Therefore, the manufacturing cost can be reduced by that amount. The support shaft 7a may be formed in a circular tube shape, and an oil supply hole may be provided in the axially intermediate portion to supply oil to the radial needle bearing 10. Similarly, the rocker shaft 5 is formed in a circular tube shape, and an oil supply hole is provided in a portion located inside the both through holes 4 and 4 at an axially intermediate portion of the rocker shaft 5. The sliding contact portion between the inner peripheral surface of the rocker and the outer peripheral surface of the rocker shaft 5 can be lubricated.

[Second Example of Embodiment] FIGS. 6 to 7 illustrate a second example of an embodiment of the present invention, corresponding to claims 1 to 3. In the case of this example, it is arranged in parallel to each other at a predetermined interval, and is provided in the middle portion of a pair of rocker arms 14a, 14a that are coupled to each other by at least one connecting portion 17 so that relative displacement is impossible. Cylindrical portions 16 and 16 are formed by burring the peripheral portions of the holes 4a and 4a. The cylindrical portions 16 and 16 have a function of ensuring the insertion length of the rocker shaft 5 (see FIG. 2) with respect to the through holes 4a and 4a and suppressing wear of the swing support portion. Since the structure and operation of the other parts are the same as those of the cam follower device shown in the first embodiment, the description of the equivalent parts is omitted.

  In the present invention, the connecting part for integrally connecting a pair of rocker arms is a problem in the assembled state of the cam follower device, the engine, and the assembled state on the edge of the rocker arm. It can be formed at a position that does not become necessary. However, considering the performance improvement of the engine incorporating the rocker arm (followability at high rotation), the position where the connecting portion is formed is preferably closer to the through hole through which the rocker shaft is inserted. This is because the moment of inertia around the rocker shaft can be reduced as the position is closer to the through hole.

In each of the above-described embodiments, a structure (single roller type) in which one tappet roller is arranged around the support shaft is employed. However, when carrying out the present invention, a structure in which two tappet rollers of an outer diameter side and an inner diameter side, which are concentrically and relatively rotatable with each other, are arranged around the support shaft (double roller type) ) Can also be adopted.
Although not shown, the structure of the present invention can be applied to a screw type adjuster system, an HLA system combined with a lash adjuster, or the like.

The side view which shows the 1st example of embodiment of this invention in the state integrated in the valve operating mechanism of the engine. The figure seen from the upper part of FIG. The expanded AA sectional view of FIG. The B section enlarged view of FIG. (A) is a figure explaining the 1st process of giving a punching process to one metal and forming a rocker arm, (b) explaining the 2nd process of giving a bending process after a punching process and forming a rocker arm. To do. The figure which looked at the rocker arm of the structure which formed the cylindrical part in the through-hole from the top. The perspective view of the rocker arm of the structure which formed the cylindrical part in the through-hole. The partial side view of the valve operating mechanism of the engine which assembled | attached the 1st example of the conventional cam follower apparatus. The expanded DD sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cam shaft 2 Cam 3, Rocker arm 4, 4a Through-hole 5 Rocker shaft 6 Support wall part 7, 7a Support shaft 8, 8a Support hole 9 Tappet roller 10 Radial needle bearing 11 Adjustment screw 12 Valve body 13 Return springs 14, 14a Rocker arm
15 Convex part 16 Cylindrical part 17 Connecting part

Claims (3)

  A cam follower device used by being incorporated in a valve operating mechanism of an engine in which at least one of an air supply valve and an exhaust valve provided in one cylinder is two or more, and is parallel to each other at a predetermined interval. A pair of plate-like rocker arms that are connected to each other at least at one connecting portion so that relative displacement is impossible, and formed at positions where they are aligned with each other at one end or an intermediate portion of both rocker arms. A pair of concentric support holes, and a support shaft fixed in a state of being spanned between the two rocker arms by fitting both ends of the support holes into the support holes, and an intermediate portion around the support shaft A tappet roller that is rotatably supported, and a pair of pressing portions provided at the other end portions of the rocker arms directly or via another member, and is incorporated in the valve operating mechanism, the tappet roller The outer peripheral surface, is brought into contact with the outer peripheral surface of a cam fixed to the camshaft, the respective pressing portions, the two air supply valve or one by one thrust against the cam follower device in the proximal end face of the two exhaust valves.   A pair of support holes that are concentric with each other are formed at one end of the pair of rocker arms, and a pair of through holes that are concentric with each other are formed at positions that are aligned with each other at an intermediate portion between the two rocker arms. In a state where it is incorporated in the valve operating mechanism, a rocker shaft, which is a fixed shaft provided in parallel with the camshaft, is inserted into these through holes, and the rocking displacement of both rocker arms around the rocker shaft is reduced. The cam follower device according to claim 1, which is enabled.   A pair of plate-like rocker arms, which are coupled to each other by at least one continuous portion so as not to be relatively displaced, are formed by punching and bending a single metal plate. The cam follower device according to claim 1 or 2.

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