JP5014198B2 - Camshaft drive device for vehicle engine - Google Patents

Description

  The present invention relates to at least two camshafts arranged in parallel to each other, two sprockets respectively provided at end portions of the two camshafts, and timings wound around the two sprockets. The present invention relates to a camshaft drive device for a vehicle engine comprising a chain and a chain guide for guiding an upper surface of a timing chain between the two sprockets.

Such an engine camshaft drive device is known from Patent Document 1 and Patent Document 2 below. In this camshaft drive device, the timing chain spanned between the intake sprocket and the exhaust sprocket is horizontally arranged, and the chain guide for guiding the upper surface thereof is also horizontally arranged.
Japanese Patent No. 3149713 JP 2000-257413 A

  By the way, in the above-mentioned conventional one, the sliding part between the timing chain and the chain guide is lubricated by the oil held therein, but the timing chain moves from the upstream side to the downstream side in the rotational direction. The oil held in the part is dragged to the timing chain and is discharged from the sliding part, which may cause insufficient lubrication of the timing chain.

  The present invention has been made in view of the above circumstances, and when guiding the upper surface of a timing chain spanned between sprockets provided on at least two camshafts with a chain guide, an oil is provided between the timing chain and the chain guide. The purpose is to secure lubrication performance by holding

To achieve the above object, according to the first aspect of the present invention, at least two camshafts arranged in parallel to each other, and 2 provided at end portions of the two camshafts, respectively. and number of sprockets, said the two wound around the timing chain sprocket, the camshaft driving device for an engine that includes a chain guide for guiding the upper surface of the timing chain between the two sprockets, the chain guide Is a chain sliding contact portion extending along the timing chain and slidingly contacting the upper surface of the timing chain, a flat mounting portion fixed to the engine body, and the chain sliding contact portion connected to the mounting portion. and a flat support for supporting a while installed vehicle body horizontally mounted engine to the vehicle body, the chain guide , As the chain sliding portion upstream side in the rotational direction of the timing chain is lower than the downstream side, and the chain sliding portion as viewed in a projection plane perpendicular to the axis of the camshaft with respect to the mounting portion Thus, a camshaft drive device for a vehicle engine is proposed, which is arranged so as to intersect in an X shape at a longitudinal intermediate portion of the mounting portion .

According to the invention described in claim 2, in addition to the structure of claim 1, the axis of one camshaft of the two camshafts is a cylinder axis rather than the axis of the other camshaft. A camshaft drive device for a vehicle engine , wherein the chain sliding contact portion extends at an angle with respect to a horizontal plane so as to follow a common tangent line of the two sprockets. Is proposed.

According to the invention described in claim 3, in addition to the configuration of claim 1 or 2, the attachment portion of the chain guide is fixed to the engine body with two bolts, and between the two bolts. A camshaft drive device for a vehicle engine is proposed in which the chain sliding contact portion intersects the attachment portion.

According to the invention described in claim 4, in addition to the configuration of any one of claims 1 to 3, the chain sliding contact portion is provided on the upstream side and the downstream side in the rotational direction of the timing chain. A vehicular engine camshaft drive device is proposed, in which a concave portion is formed in the end portion so as to bend upward as viewed from the projection plane .

According to the invention described in claim 5, in addition to the structure of any one of claims 1 to 4, the engine body includes a plurality of chain guides each having the same upper surface. A camshaft drive device for a vehicle engine is proposed , characterized in that a support portion is provided and the mounting portion is fastened to the upper surface of the chain guide support portion .

  The cylinder head 12 of the embodiment corresponds to the engine body of the present invention, the intake camshaft 21 and the exhaust camshaft 22 of the embodiment correspond to the camshaft of the present invention, and the intake sprocket 23 of the embodiment and The exhaust sprocket 24 corresponds to the sprocket of the present invention, and the second fixed chain guide 30 of the embodiment corresponds to the chain guide of the present invention.

  According to the configuration of claim 1, the timing chain is wound around two sprockets respectively provided at the ends of the two camshafts, and the upper surface of the timing chain between the two sprockets is guided by the chain guide. In the state where the engine is attached to the vehicle body and the vehicle body is horizontally installed, the chain sliding contact portion of the chain guide is arranged so that the upstream side in the rotational direction of the timing chain is lower than the downstream side. Even if the oil existing between the timing chains is scraped from the upstream side in the rotational direction of the timing chain to the downstream side, the oil flows down from the high side downstream in the rotational direction of the timing chain to the low side downstream by gravity. Oil is held between the sliding part of the chain and the timing chain to ensure lubrication performance of the sliding part. Rukoto can.

In addition, as seen from the projection plane orthogonal to the axis of the camshaft , the chain sliding contact portion intersects the attachment portion of the chain guide to the engine body in the X-shape at the intermediate portion in the longitudinal direction of the attachment portion. The chain sliding contact portion is brought closer to the highly rigid mounting portion fixed to the engine body to increase the rigidity of the chain sliding contact portion itself, and the bending moment acting on the mounting portion due to the load applied to the chain sliding contact portion from the timing chain is increased. The chain guide can be made lighter and lighter.

  Further, according to the configuration of claim 3, the attachment portion of the chain guide is fixed to the engine body with two bolts, and the chain sliding contact portion intersects the attachment portion between the two bolts. The support rigidity of the chain sliding contact portion with respect to the attachment portion of the chain guide can be further increased.

According to the fourth aspect of the present invention, the recesses that are recessed so as to bend upward when viewed from the projection plane are formed only at the upstream and downstream ends of the timing chain of the chain sliding contact portion. When engaging and disengaging from the sliding contact portion, the timing chain can be released to the recess to reduce the biting sound.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 5 show an embodiment of the present invention. FIG. 1 is a front view of an engine, FIG. 2 is an enlarged view of a part 2 in FIG. 1, FIG. 3 is a view in the direction of arrows 3 in FIG. Is an exploded perspective view of the chain guide, and FIG. 5 is an enlarged view of a portion 5A and a portion 5B of FIG.

  As shown in FIG. 1, an automobile engine E includes a cylinder block 11, a cylinder head 12 coupled to the upper surface of the cylinder block 11, a head cover 13 coupled to the upper surface of the cylinder head 12, and a cylinder block 11. And a lower block 14 coupled to the lower surface.

  A crankshaft 16 is rotatably supported between the cylinder block 11 and the lower block 14, and a crank sprocket 17 is provided at the shaft end of the crankshaft 16. Further, a camshaft holder 18 and camshaft caps 19 and 20 are coupled to the upper surface of the cylinder head 12 so as to be covered with the head cover 13, and are rotatably supported between the camshaft holder 18 and the camshaft caps 19 and 20. An intake sprocket 23 and an exhaust sprocket 24 are provided at the shaft ends of the intake camshaft 21 and the exhaust camshaft 22, respectively. A timing chain 25 is wound around the crank sprocket 17, the intake sprocket 23 and the exhaust sprocket 24.

  A first fixed chain guide 26 for guiding the outer peripheral surface of the timing chain 25 is provided between the tight side of the timing chain 25 rotating in the clockwise direction, that is, between the intake sprocket 23 and the crank sprocket 17, and the loose side of the timing chain 25, That is, a movable chain guide 27 that guides the outer peripheral surface of the timing chain 25 is provided between the crank sprocket 17 and the exhaust sprocket 24. The upper end of the movable chain guide 27 is pivotally supported by the cylinder head 12 by a pivot 28, and the lower end is urged by a chain tensioner 29 provided in the cylinder block 11 to apply tension to the timing chain 25. . Further, a second fixed chain guide 30 that guides the outer peripheral surface (upper surface) of the timing chain 25 is provided between the intake sprocket 23 and the exhaust sprocket 24.

  As apparent from FIGS. 2 to 4, the intake camshaft 21 having the variable valve lift mechanism is provided at a higher position than the exhaust camshaft 22 not having the valve lift varying mechanism. The shaft 21 is high and the exhaust camshaft 22 side is formed in a stepped shape. The camshaft holder 18 is fastened to the upper surface of the cylinder head 12 by five bolts 31A to 31E, and the intake camshaft cap 19 is fastened together by three bolts 31A to 31C, and the remaining two bolts The exhaust camshaft cap 20 is fastened together by 31D and 31E.

  A chain guide support portion 19a protrudes from the upper surface of the intake camshaft cap 19, and a chain guide support portion 20a protrudes from the upper surface of the exhaust camshaft cap 20. The upper surfaces of both chain guide support portions 19a and 20a are the same. The height is aligned (parallel to the upper surface of the cylinder head 12). Then, the second fixed chain guide 30 is fastened together by two bolts 31B and 31D penetrating both the chain guide support portions 19a and 20a.

  The second fixed chain guide 30 includes an aluminum chain guide main body 32 and a synthetic resin chain sliding contact portion 33. The chain guide main body 32 includes a flat attachment portion 32a and a flat support portion 32b that is connected to a position twisted with respect to the attachment portion 32a. Two bolt holes 32c and 32d are formed in the attachment portion 32a, and two thin insertion pieces 32e and 32f located at both ends in the longitudinal direction are formed in the support portion, and one elongated hole 32g located in the center. Is formed.

On the other hand, slits 33a and 33b that open in the horizontal direction are formed on the upper surfaces of both ends in the longitudinal direction of the substantially strip-shaped chain sliding contact portion 33, and a protrusion 33c that protrudes upward is formed at the center thereof. Tapered portions 33d and 33e that are notched upward are formed at both ends in the longitudinal direction of the chain sliding contact portion 33, and projections orthogonal to the axes of the camshafts 21 and 22 are formed inside the tapered portions 33d and 33e. Concave portions 33f and 33g are formed so as to be curved upward as viewed on the surface (that is, FIG. 2) (see FIG. 5). While elastically deforming the chain sliding contact portion 33, the insertion pieces 32e and 32f of the support portion 32b of the chain guide main body 32 are inserted into the slits 33a and 33b of the chain sliding contact portion 33, and the chain is inserted into the long hole 32g of the support portion 32b. By fitting the protrusion 33 c of the sliding contact portion 33, the chain sliding contact portion 33 is attached to the support portion 32 b of the chain guide main body 32.

  As is apparent from FIG. 2, the chain guide main body 32 of the second fixed chain guide 30 is inclined by an angle θ so that the support portion 32b, that is, the chain sliding contact portion 33 is twisted with respect to the mounting portion 32a. . That is, the attachment portion 32a of the chain guide main body 32 is horizontally arranged, whereas the chain sliding contact portion 33 is higher on the intake sprocket 23 side on the downstream side of the timing chain 25 than on the exhaust sprocket 24 side on the upstream side in the rotation direction. It is inclined to become.

  Thus, when the timing chain 25 rotates in the clockwise direction in FIG. 3, its outer peripheral surface (upper surface) is guided in sliding contact with the lower surface of the chain sliding contact portion 33 of the second fixed chain guide 30, and the intake sprocket 23 and the exhaust sprocket are guided. The tooth jump of the timing chain 25 with respect to the 24 sprocket teeth is prevented. At this time, since the length d2 of the chain sliding contact portion 33 is longer than the distance d1 between the intake camshaft 21 and the exhaust camshaft 22, tooth skipping of the timing chain 25 can be more reliably prevented. Is done.

  The oil supplied to the internal space of the cylinder head 12 adheres to the timing chain 25, and the oil is scattered outward by centrifugal force and supplied to the lower surface of the chain sliding contact portion 33. The sliding surface between the upper surface and the lower surface of the chain sliding contact portion 33 is lubricated. The oil present on the sliding surface is dragged by the rotating timing chain 25, moves from the exhaust sprocket 24 side to the intake sprocket 23 side, and tends to be discharged from the intake sprocket 23 side. However, in a state where the engine E is mounted on the vehicle body and the vehicle body is installed horizontally, the chain sliding contact portion 33 is inclined so that the intake sprocket 23 side is high and the exhaust sprocket 24 side is low. The oil on the surface flows in the opposite direction to the timing chain 25 due to gravity and is held on the sliding surface without being discharged from the intake sprocket 23 side, so that the lubricating performance of the timing chain 25 is improved.

The chain sliding contact portion 33 of the second fixed chain guide 30 receives the upward load in the cylinder axial direction due to the centrifugal force acting on the timing chain 25, but as shown in FIG. 2, the direction orthogonal to the rotation surface of the timing chain 25 As seen (that is, when viewed from a projection plane orthogonal to the axis of the camshafts 21 and 22) , the support portion 32b, that is, the chain sliding contact portion 33 with respect to the attachment portion 32a of the chain guide body 32 is the longitudinal direction of the attachment portion 32a. Since it is arranged so as to intersect in an X shape at the middle portion in the direction, a highly rigid attachment portion 32a fixed to the cylinder head 12 via the camshaft holder 18, the intake camshaft cap 19 and the exhaust camshaft cap 20 is provided. The chain sliding contact portion 33 is moved closer to the shaft to increase the rigidity of the chain sliding contact portion 33 itself, and the timing chain 2 The bending moment acting on the mounting portion 32a due to the load applied to the chain sliding contact portion 33 from 5 can be reduced, and the weight of the second fixed chain guide 30 can be reduced.

  In particular, the mounting portion 32a of the second fixed chain guide 30 is fixed to the cylinder head 12 with two bolts 31B and 31D, and the chain sliding contact portion 33 with respect to the mounting portion 32a between the two bolts 31B and 31D. Therefore, the support rigidity of the chain sliding contact portion 33 with respect to the mounting portion 32a of the second fixed chain guide 30 can be further increased.

  Further, since the upward tapered portions 33d and 33e are formed on the lower surfaces of both ends in the longitudinal direction of the chain sliding contact portion 33, the timing chain 25 can be smoothly engaged with or detached from the chain sliding contact portion 33. In addition, since the recesses 33f and 33g that are recessed upward so as to allow the timing chain 25 to escape are formed on the lower surface in the vicinity of both ends in the longitudinal direction of the chain sliding contact portion 33, the biting sound of the endless chain 25 can be reduced.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the second fixed chain guide 30 is supported on the cylinder head 12 via the camshaft holder 18, the intake camshaft cap 19, and the exhaust camshaft cap 20. You may do it.

Front view of the engine 2 enlarged view of FIG. 3 direction arrow view of FIG. Exploded perspective view of chain guide 2A and 5B enlarged view of FIG.

12 Cylinder head (engine body)
21 Intake camshaft (camshaft)
22 Exhaust camshaft (camshaft)
23 Intake sprocket
24 Exhaust sprocket (sprocket)
25 Timing chain 30 Second fixed chain guide (chain guide)
31B Bolt 31D Bolt 32a Mounting part 33 Chain sliding contact part 33f Concave part 33g Concave part E Engine

Claims (5)

At least two camshafts (21, 22) arranged in parallel to each other, and two sprockets (23, 24) respectively provided at ends of the two camshafts (21, 22), A timing chain (25) wound around the two sprockets (23, 24), and a chain guide (30) for guiding an upper surface of the timing chain (25) between the two sprockets (23, 24); In an engine camshaft drive device comprising:
The chain guide (30) extends along the timing chain (25) and is a flat portion fixed to the engine main body (12) and a chain sliding contact portion (33) for slidingly contacting the upper surface of the timing chain (25). A mounting portion (32a) and a flat support portion (32b) connected to the mounting portion (32a) and supporting the chain sliding contact portion (33),
In a state where the engine (E) is attached to the vehicle body and the vehicle body is installed horizontally, the chain sliding contact portion (33) of the chain guide (30) is located on the upstream side in the rotational direction of the timing chain (25) from the downstream side. And the chain sliding contact portion (33) of the mounting portion (32a) with respect to the mounting portion (32a) is viewed from a projection plane orthogonal to the axis of the camshaft (21, 22). A camshaft drive device for a vehicular engine, wherein the camshaft drive device is arranged so as to intersect in an X shape at an intermediate portion in a longitudinal direction . The axis of one camshaft (21) of the two camshafts (21, 22) is disposed at a position higher in the cylinder axial direction than the axis of the other camshaft (22), and the chain slide 2. The vehicle engine according to claim 1 , wherein the contact portion (33) is inclined with respect to a horizontal plane so as to be along a common tangent line of the two sprockets (23, 24) . Camshaft drive device. The attachment portion ( 32a ) of the chain guide (30) is fixed to the engine body (12) with two bolts (31B, 31D), and the attachment portion ( 32a ) between the two bolts (31B, 31D). ) the chain sliding portion (33) is characterized by crossing the camshaft driving device for a vehicle engine according to claim 1 or 2. The chain sliding contact portion (33) is formed with concave portions (33f, 33g) which are recessed so as to bend upward when viewed from the projection surface only at the upstream and downstream ends of the timing chain (25) in the rotational direction. The camshaft drive device for a vehicle engine according to any one of claims 1 to 3, wherein the camshaft drive device is for a vehicle engine. The engine body (12) is provided with a plurality of chain guide support portions (19a, 20a) each having the same upper surface, and the attachment to the upper surfaces of the chain guide support portions (19a, 20a). The camshaft drive device for a vehicle engine according to any one of claims 1 to 4, wherein the portion (32a) is fastened.

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