JP6461640B2 - Roller type rocker arm - Google Patents

Description

  The present invention relates to a rocker arm type valve operating mechanism for an internal combustion engine, and more particularly to a structure of a sliding type roller rocker arm with improved friction performance.

  In a valve mechanism of a four-stroke internal combustion engine, a camshaft lift operation for opening and closing an intake / exhaust valve is transmitted directly using a tappet, and a rocker arm is transmitted using a rocker arm. It is classified as a formula. Both the tappet and rocker arm are installed between the camshaft and the intake / exhaust valve.When the valve is opened, it lifts while overcoming the valve spring reaction force, and when it is closed, it moves while being pushed back by the valve spring. A load that combines the inertial force of the valve system is constantly generated.

  In recent years, for the purpose of improving fuel efficiency, a rocker arm provided with a roller is often used. This roller type includes a main body called a body, an outer ring roller that slides with a camshaft, a shaft that supports the outer ring roller, a small-diameter shaft called a roller between the shaft and the outer ring roller, or a hollow roller called an inner ring. Consists of four parts. The former method using a roller is classified as a rolling method, and the latter method using an inner ring roller is classified as a sliding method.

  FIG. 1A shows a schematic perspective view of a sliding rocker arm, and FIG. 1B shows a schematic perspective view of a rolling rocker arm. However, the body of the rocker arm is omitted here. The sliding rocker arm 10 includes a roller shaft 12, an inner ring roller 14 rotatably attached to the roller shaft 12, and an outer ring roller 16 rotatably attached to the outer periphery of the inner ring roller 14. The rolling rocker arm 20 includes a roller shaft 22, a plurality of needle rollers 24 that are rotatably attached to the outer periphery of the roller shaft 22, and a roller 26 that is rotatably attached to the outer periphery of the needle roller 24. .

  FIG. 2 is a view showing an example of a rolling-type rocker arm installed between the cam 40 of the camshaft and the valve stem of the intake / exhaust valve 37. The rocker arm includes a body 30 that rotatably holds a roller 26 as shown in FIG. 1B. One end 32 of the body 30 is supported by a pivot portion 34, and the other end 36 is intake / exhaust. A valve spring 39 that abuts against the cap 38 of the valve 37 and biases the end portion 36 of the rocker arm is attached below the cap 38. Thus, the roller 26 is brought into contact with the cam 40, and the rotational movement of the cam 40 is transmitted to the body 30, and the other end 36 moves the intake / exhaust valve 37 up and down according to the rotation of the cam 40. A sliding rocker arm can be used as well. FIG. 2A shows another example in which the rocker arm is supported by a hydraulic lash adjuster. As shown in the figure, one end 32 of the rocker arm is brought into contact with a plunger 52 having a hemispherical top, and the plunger 52 is supported by a lash adjuster 50. The lash adjuster 50 supports the plunger 52 so as to be slidable in the axial direction. Such a lash adjuster type rocker arm is disclosed in Patent Documents 1 and 2, and allows lubricating oil to be easily supplied to the lubricating oil hole of the roller shaft via the lash adjuster.

  Since the rolling type is used in a state where the roller rolls during engine operation, the friction performance is better than that of the sliding type. However, the roller is in a sliding state close to line contact with the shaft or outer ring. In particular, the roller and the shaft have a small outer diameter and contact between the shaft and the convex R, so that the surface pressure is higher than the Hertz contact theory.

  On the other hand, the sliding type supports the lift load of the camshaft on the inner circumference of the outer ring roller and the outer circumference of the inner ring roller, the inner circumference of the inner ring roller, and the outer circumference of the roller shaft. The inner ring roller and roller shaft, which have the highest surface pressure, have a larger inner ring roller inner diameter than the roller and have a concave R and convex R contact with the roller shaft, so the surface pressure is lower than the rolling type. used. Since each sliding surface has a clearance and slides and moves relative to each other, the boundary lubrication state occurs particularly in the low rotation range, and the friction performance deteriorates.

  In order to improve fuel consumption, it is necessary to reduce the friction of these sliding portions. Further, in order to ensure the function of smoothly transmitting the lift operation over a long period of time, it is necessary for these sliding portions not to be worn or seized. In such a conventional rocker arm, techniques for suppressing wear (Patent Document 3) and supplying lubricating oil efficiently (Patent Documents 4 and 5) are disclosed. In addition, a technique for preventing damage and seizure by processing a lubricating film on the peripheral surface of the inner ring roller is disclosed (Patent Document 6).

JP 2011-1906 A JP 2012-154226 A JP 2008-255883 A JP 2007-23817 A JP 2007-263023 A JP 2000-34907 A

  In the sliding rocker arm, the inner circumference of the outer ring roller and the outer circumference of the inner ring roller, the inner circumference of the inner ring roller, and the outer circumference of the roller shaft function as sliding surfaces, and clearances are provided in these portions. Conventionally, the sliding surface is manufactured by finishing the shape by polishing and then adjusting the surface roughness with a barrel.

  At the time of movement, the lubrication to the sliding surface is carried out by splashing using splashed lubricating oil existing in the atmosphere inside the cylinder head, so that the supply amount of lubricating oil is originally small. Therefore, there was a concern about friction on the sliding surface. In particular, the conventional sliding rocker arm has a problem that in a low rotation region (mainly at a low rotation of 1000 rpm or less, such as when idling), the boundary lubrication state causes a larger friction than the rolling rocker arm. Further, in the high rotation range (mainly high rotation of 2500 rpm or more), there is a problem that the weight must be reduced because the friction is small when the rocker arm weight is light.

  In order to solve the above problems, an object of the present invention is to provide a roller-type rocker arm that reduces friction from a low engine speed range to a high engine speed range.

  A roller-type rocker arm according to the present invention has a function of transmitting a rotational operation of a cam to an intake / exhaust valve, and includes a roller shaft, an inner ring roller mounted on an outer peripheral surface of the roller shaft, An outer ring roller slidably mounted on the outer circumferential surface of the inner ring roller, and a resin member is fastened to the inner circumference of the outer ring roller.

  Preferably, the resin member is an annular member attached to the inner periphery of the outer ring roller. Preferably, the annular member is press-fitted into the inner periphery of the outer ring roller. Preferably, a plurality of grooves are formed on the inner periphery of the outer ring roller, and the resin member is filled in the plurality of grooves. Preferably, the plurality of grooves are annular grooves formed in parallel with the sliding direction of the outer ring roller. Preferably, the plurality of grooves are linear grooves formed in a direction orthogonal to the sliding direction of the outer ring roller. Preferably, the resin member is filled into the plurality of grooves by injection molding. Preferably, the resin member is made of a polyether ether ketone resin, a polyphenylene sulfide resin, a polytetrafluoroethylene resin, a polyether sulfone resin, a polybenzimidazole resin, a polyimide resin, or a polyamideimide resin. Preferably, the resin member includes carbon fibers, CNT (carbon nanotubes), CNC (carbon nanocoils), or reinforcing fibers reinforced with glass fibers. Preferably, the reinforcing fiber is disposed substantially parallel to the sliding direction of the inner ring roller. Preferably, an amorphous hard carbon coating is formed on at least one of the inner peripheral surface of the outer ring roller and the counterpart member that slides with the inner peripheral surface.

  According to the present invention, by attaching a resin member to the inner circumference of the outer ring roller, the friction from the low rotation range to the high rotation range of the engine is reduced, and the weight of the outer ring roller is reduced while maintaining the strength. be able to.

1A is a schematic perspective view showing a conventional roller rocker arm (slip type), and FIG. 1B is a schematic perspective view showing a conventional roller rocker arm (rolling type). It is a schematic diagram which shows an example by which a rocker arm is operated with a cam. It is a schematic diagram which shows the other example in which the rocker arm was applied to the internal combustion engine. It is a typical external appearance perspective view of the roller type rocker arm which concerns on the Example of this invention. It is a schematic diagram when a part of body of the rocker arm concerning a 1st example is removed. It is the figure which showed each part component of the rocker arm concerning a 1st Example, Drawing 5 (A) is a perspective view of a roller axis, Drawing 5 (B) is a perspective view of an inner ring roller, and Drawing 5 (C) is It is a perspective view of the outer ring | wheel roller containing a bush. It is a perspective view which shows the structure of the outer ring | wheel roller main body and bush which concern on a 1st Example. It is a figure which shows the cross section of the rocker arm which concerns on a 1st Example. FIG. 8A is an external perspective view of the outer ring roller of the rocker arm according to the second embodiment. FIG. 8B is a cross-sectional view of the rocker arm including the outer ring roller according to the second embodiment. It is sectional drawing explaining the structure of the outer ring | wheel roller which concerns on a 2nd Example. FIG. 10A is a perspective view of an outer ring roller according to a modification of the second embodiment, and FIG. 10B is a sectional view thereof.

  Next, the form for implementing this invention is demonstrated in detail. It should be noted that in the drawings, each part is highlighted for easy understanding, and is different from an actual scale.

  FIG. 3 is a perspective view showing the entire rocker arm according to the first embodiment, and FIG. 4 is a view in which a part of the body of the rocker arm according to the first embodiment is removed. The rocker arm according to the first embodiment is one of the components constituting a rocker arm type valve operating mechanism of a four-stroke internal combustion engine, and relates to a rocker arm that slides while sliding completely.

  As shown in FIGS. 3 and 4, the rocker arm 100 according to the first embodiment includes a body 110, a roller shaft 120 fixed in the body 110, and an inner ring roller attached on the outer periphery of the roller shaft 120. 130 and an outer ring roller 140 rotatably mounted on the outer circumference of the inner ring roller 130. Further, an annular bush 150 made of resin is attached to the inner peripheral surface of the outer ring roller 140 as will be described later.

  The body 110 is a metal member that supports the roller shaft 120, the inner ring roller 130, and the outer ring roller 140, and an opening 112A for supporting the pivot portion 34 (see FIG. 2) is formed in one end portion 112. The other end 114 is brought into contact with the cap 38 of the valve stem of the intake / exhaust valve. A pair of spaced side walls 116A and 116B are formed between one end 112 and the other end 114 of the body 110, and circular through holes 118 are formed in the pair of side walls 116A and 116B, respectively. It is formed. A roller shaft 120 is attached in the through hole 118 of the pair of side walls 116A and 116B.

  As shown in FIG. 5A, the roller shaft 120 is a cylindrical metal member having a uniform diameter D1, and is inserted into the through holes 118 of the pair of side walls 116A and 116B as described above. . Preferably, the diameter D1 of the roller shaft 120 is formed to be approximately equal to or slightly larger than the diameter of the through hole 118, and the roller shaft 120 is fastened into the through hole 118 by caulking or the like. Thereby, the roller shaft 120 is fixed to the body 110.

  The inner ring roller 130 is an annular metal member that is attached so as to cover the outer periphery 122 of the roller shaft 120 between the pair of side walls 116A and 116B. As shown in FIG. 5B, the inner ring roller 130 has an inner peripheral surface 132 having an inner diameter D2 and an outer peripheral surface 134 having an outer diameter D3. The inner diameter D2 is formed to be somewhat smaller than the diameter D1 of the roller shaft 120, that is, D1> D2, and the roller shaft 120 is fastened into the inner ring roller 130 by press-fitting or caulking. When such a relationship of D1> D2 is established, the inner ring roller 130 is fixed to the roller shaft 120. However, by setting D1 <D2, a clearance may be provided between the inner ring roller 130 and the roller shaft 120 so that the inner ring roller 130 can freely slide on the outer peripheral surface 122 of the roller shaft 120.

  The outer ring roller 140 is an annular composite member that is attached so as to cover the outer periphery 134 of the inner ring roller 130 between the pair of side walls 116A, 116B. That is, the outer ring roller 140 includes a metal outer ring roller main body 142 and a resin bush 150 fastened or fixed to the inner periphery of the outer ring roller main body 142.

  FIG. 6A is a perspective view of the outer ring roller body, and FIG. 6B is a perspective view of the bush. The outer ring roller body 142 has an outer peripheral surface 146 and an inner peripheral surface 144 having an inner diameter D4. As shown in FIG. 6B, the bush 150 has an inner peripheral surface 152 defined by an inner diameter D5 and an outer peripheral surface 154 defined by an outer diameter D6. The outer diameter D6 of the bush 150 is formed to be equal to or somewhat larger than the inner diameter D4 of the outer ring roller body 142, that is, D6 ≧ D4. Preferably, the bush 150 is fitted into the inner periphery of the outer ring roller body 142 by press fitting or the like. Thereby, the bush 150 is fastened to the inner periphery of the outer ring roller main body 142, and the bush 150 and the outer ring roller main body 142 are practically integrated. The inner diameter D5 of the bush 150 is somewhat larger than the outer diameter D3 of the inner ring roller 130, that is, has a certain clearance S1 (see FIG. 7) so that D5> D3. As a result, the inner peripheral surface 152 of the bush 150 can slide freely on the outer peripheral surface 134 of the inner ring roller 130. The inner periphery of the outer ring roller main body 142 and the outer peripheral surface of the bush 150 may be other than a cylindrical shape. For example, the inner periphery of the outer ring roller main body 142 and the outer peripheral surface of the bush 150 may be fitted in a complementary uneven shape.

  The resin material constituting the bush 150 is preferably one having excellent sliding characteristics with a metal material, wear resistance, and affinity with a lubricating oil, such as PEEK (polyether ether ketone). , PPS (polyphenylene sulfide), PTFE (polytetrafluoroethylene), PES (polyethersulfone), PBI (polybenzimidazole), PI (polyimide), PAI (polyamideimide), and the like. The bush 150 is formed by molding and processing such a resin material.

  More preferably, a reinforcing member is mixed in the resin material in order to enhance the mechanical strength, wear resistance, etc. of the resin material. The reinforcing member is, for example, a reinforcing fiber such as carbon fiber, CNT (carbon nanotube), CNC (carbon nanocoil), or glass fiber. Along with the reinforcing fibers, lubricating materials such as graphite and molybdenum disulfide, and wear-resistant fine particles such as metals and ceramics may be mixed. Furthermore, when such a reinforced fiber is included in the resin material, the reinforced fiber is arranged so as to be substantially parallel to the sliding direction (circumferential direction) of the inner ring roller 130, thereby causing friction. Further reduce. If the radial thickness of the bush 150 is 25 to 60% of the radial thickness of the outer ring roller 140, it is preferable because the rigidity and strength necessary for the outer ring roller body 142 can be maintained and the strength of the bush 150 can be secured. .

  FIG. 7 is a view showing a cross section of the rocker arm according to the first embodiment. In the conventional rocker arm, the inner metal surface of the outer ring roller and the outer metal surface of the inner ring roller slide, and the slip between these metals becomes boundary lubrication in a low rotation range such as when idling, resulting in high friction. Become. On the other hand, in the first embodiment, the bush 150 is fastened to the inner periphery of the outer ring roller main body 142, so that the slip between the outer ring roller 140 and the inner ring roller 130 becomes a metal-to-resin, and the conventional metal pair Friction in the low rotation range can be reduced as compared with metal sliding. Further, the bush 150 makes the resin from metal by this volume, so that the weight can be reduced compared to the conventional rocker arm, and the starting torque of the outer ring roller and the friction in the high rotation range can be reduced. As a result, low friction can be realized in the low to high engine speed range.

  Next, a rocker arm according to a second embodiment will be described. In the first embodiment, an example in which a bush formed of a resin material is fastened to the inner circumference of the outer ring roller is shown. However, in the second embodiment, a plurality of grooves are formed on the inner circumference of the outer ring roller. The resin material is filled into the plurality of grooves.

  FIG. 8A is a schematic perspective view of the outer ring roller of the rocker arm according to the second embodiment, and FIG. 8B is a cross-sectional view of the rocker arm according to the second embodiment. As in the first embodiment, the outer ring roller 140A according to the second embodiment has an inner peripheral surface 144 and an outer peripheral surface 146, and the inner peripheral surface 144 is orthogonal to the axial direction or the sliding direction. A plurality of grooves 160 are formed in the direction. One groove 160 is formed to be continuous in the circumferential direction of the inner peripheral surface 144, and has a constant width and a constant depth. The cross-sectional shape of the groove 160 is processed into a rectangular shape as illustrated, for example. A plurality of such grooves 160 are formed on the inner peripheral surface 144 of the outer ring roller 140 at an equal pitch. Further, the resin 170 is filled in the groove 160. The resin 170 is made of the same resin material as in the first embodiment, and the resin 170 is formed in the groove 160 by injection molding such a resin material. The resin 170 is preferably configured to form the same plane as the inner peripheral surface 144 of the outer ring roller 140, and the inner peripheral surface 144 and the resin 170 slide on the outer peripheral surface 134 of the inner ring roller 130 in a freely rotatable manner.

  FIG. 9 is a cross-sectional view illustrating a specific example of the outer ring roller according to the second embodiment. As shown in FIG. 9A, the groove 160 is processed to have a width Lx and a depth Ly. The depth Ly is preferably 25 to 60% with respect to the radial thickness T of the outer ring roller 140A. One groove 160 is separated by an adjacent groove 160 and a partition wall 162, and the partition wall 162 has a width W. In the example shown in the figure, the relationship is Lx> W, but the relationship may be Lx = W or Lx <W. Moreover, the groove | channel 160 located in the both ends of the outer ring | wheel roller 140A is formed in the position prescribed | regulated by the partition 162A, 162B from the edge part, and the width | variety of the partition 162A, 162B is selected suitably. The groove 160 can be formed by, for example, processing using a cutting member or laser processing.

  As shown in FIG. 9B, the groove 160 is filled with a resin 170. Preferably, the resin 170 is filled in the groove 160 so as to form the same surface as the inner peripheral surface 144 of the outer ring roller 140A, that is, the surfaces of the partition walls 162, 162A, and 162B. The resin 170 is filled in the groove 160 by, for example, injection molding.

  FIG. 9C illustrates another configuration example of the resin 170. The resin 170 may be formed so as to protrude by a height h from the surface of the partition walls 162, 162A, 162B. The height h is preferably smaller than the clearance S1 between the outer ring roller 140A and the inner ring roller 130, and is a size that is worn during the initial leveling operation of the outer ring roller 140A and the inner ring roller 130.

  FIG. 9D illustrates another configuration example of the resin 170. The resin 170 may be formed so as to cover the entire inner peripheral surface of the outer ring roller 140A so that the surfaces of the partition walls 162, 162A, 162B of the outer ring roller 140A are not exposed.

  Next, a modification of the second embodiment of the present invention will be described. FIG. 10A is a perspective view of an outer ring roller 140B according to a modification of the second embodiment. As shown in the figure, a plurality of grooves 166 are formed in the inner peripheral surface 144 of the outer ring roller 140B in a direction orthogonal to the sliding direction of the outer ring roller 140B. Each groove 166 has the same size and is formed at equal intervals. In the figure, the groove 166 communicates from one end to the other end, but a partition wall 162 may be provided at the end. FIG. 10B is a cross-sectional view of the outer ring roller 140B when the resin 172 is filled in the groove 166. FIG. The resin 172 is filled in the groove 166 so as to form the same surface as the inner peripheral surface 144 on the inner peripheral surface 144 of the outer ring roller 140B. Further, as shown in FIGS. 9C and 9D, the resin 172 may be formed so as to protrude from the inner peripheral surface 144 by the height h.

  As described above, according to the second embodiment, the resin is filled in the groove on the inner peripheral surface of the outer ring roller, and the resin-to-metal slip is realized between the outer ring roller and the inner ring roller. As in the case of, the friction in the low rotation range can be reduced.

  In the said Example, although the cross section of the groove | channel formed in the inner periphery of an outer ring | wheel roller was made into rectangular shape, this is an example and another shape, for example, circular arc shape, may be sufficient. Furthermore, the size, number, pitch, and the like of the grooves formed on the inner periphery of the outer ring roller can be changed or selected as appropriate according to the desired purpose and request. Further, although the groove 160 is formed so as to be parallel to the sliding direction, the groove 160 may be formed in a spiral shape so as to have a certain angle with respect to the sliding direction. In this case, a plurality of grooves 160 may be continuous, or each groove may be discontinuous. Further, although the groove 166 shown in FIG. 10 is formed to be orthogonal to the sliding direction, the groove 166 may be formed to have a certain angle with respect to the sliding direction.

  Next, a third embodiment of the present invention will be described. In the third embodiment, an amorphous hard carbon coating (hereinafter referred to as DLC (Diamond like carbon) coating) is formed on the sliding surface of the counterpart member sliding with the bush 150 or the resin 170, that is, the outer peripheral surface of the inner ring roller 130. Is formed). Such a DLC film can be formed by a PVD method, a CVD method, a PACVD method, or the like. For example, it is preferable in terms of hardness and wear resistance that the hydrogen content formed by PVD method, particularly arc ion plating method is 0.5 atomic% or less. The film thickness of the DLC film is, for example, 0.3 to 1.5 μm, preferably 1.0 μm or less in the case of the PVD method. If it is CVD method, it can have a film thickness of about 20 micrometers.

  By forming the DLC film on the outer peripheral surface of the inner ring roller 130 that slides with the bush 150 or the resin 170, friction between the inner ring roller 130 and the outer ring roller 140 can be reduced.

  In addition, although the example which forms a DLC film in the sliding surface of the other member sliding with the outer ring | wheel roller 140 was shown in the said Example, the effect of the reduction of friction can be acquired besides said structure. In this case, a DLC film may be formed on the inner peripheral surface of the outer ring roller 140, or a DLC film may be formed on each of the inner peripheral surface of the outer ring roller 140 and the outer peripheral surface of the inner ring roller 130. Furthermore, in addition to DLC, surface treatment such as blast treatment may be applied to improve the low friction characteristics and the retention of lubricating oil, and to further reduce friction.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to specific embodiments, and the present invention can be modified based on the claims without departing from the spirit of the present invention. Can be changed.

100: Rocker arm 110: Body 120: Roller shaft 122: Outer surface 130: Inner ring roller 132: Inner surface 134: Outer surface 140: Outer ring roller 142: Outer ring roller body 144: Inner surface 146: Outer surface 150: Bush 152 : Inner peripheral surface 154: Outer peripheral surface 160: Groove 162: Partition wall 170: Resin S1: Clearance

Claims (5)

A roller-type rocker arm having a function of transmitting the rotational movement of the cam to the intake and exhaust valves,
A roller shaft, an inner ring roller mounted on the outer peripheral surface of the roller shaft, and an outer ring roller slidably mounted on the outer peripheral surface of the inner ring roller;
The outer ring roller has an annular metal roller body having an outer peripheral surface and an inner peripheral surface having an inner diameter d1, and an annular resin member bush having an inner peripheral surface and an outer peripheral surface having an outer diameter d2.
A roller-type rocker arm in which the bush is press-fitted into the roller body using the bush and the roller body having a relationship in which the outer diameter d2 is larger than the inner diameter d1 . The roller according to claim 1 , wherein the resin member is made of a polyether ether ketone resin, a polyphenylene sulfide resin, a polytetrafluoroethylene resin, a polyether sulfone resin, a polybenzimidazole resin, a polyimide resin, or a polyamideimide resin. Rocker arm. 3. The roller rocker arm according to claim 1, wherein the resin member includes carbon fiber, CNT (carbon nanotube), CNC (carbon nanocoil), or a reinforcing fiber reinforced with glass fiber. The roller-type rocker arm according to claim 3 , wherein the reinforcing fiber is disposed substantially parallel to a sliding direction of the inner ring roller. The roller type according to any one of claims 1 to 4 , wherein an amorphous hard carbon coating is formed on at least one of the inner peripheral surface of the outer ring roller and a counterpart member that slides with the inner peripheral surface. Rocker arm.

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