JP6729005B2 - Engine chain cover structure - Google Patents

Description

The present invention relates to a structure of a chain cover that covers a cam timing chain for driving a valve operating mechanism of an engine.

In the engine of this type of vehicle, a mechanism for changing the opening/closing phase of the valve according to its operating condition, that is, a variable valve timing device (VVT) is widely used as the valve operating mechanism. This VVT is attached to the shaft end of a cam shaft for driving the valve and is covered with a chain cover.

On the other hand, as a chain cover that covers a cam timing chain that rotationally drives a cam shaft, for example, in the engine disclosed in Patent Document 1, a mount member mounting seat portion to which a mount member is fixed is formed in a front cover. The mounting member mounting seat portion is formed on the front cover in a state of protruding to one side in the width direction of the engine body when viewed from the front side of the engine body.

JP, 2010-14001, A

The variable valve timing device (VVT) may be mounted overhanging forward from the engine body. If the VVT mounted by such a mounting method is left as it is, it becomes a factor that impairs the mountability of the engine in the vehicle and eventually the compactness of the vehicle. Further, the addition of a control device to the VVT and the complexity of the unit structure also cause a cost increase.

In addition, when the mount member attachment portion is provided on the chain cover, it is necessary to support a large load for mounting the engine, and thus rigidity corresponding to the load is required. In that case, since the mounting member mounting portion has a certain size or more, a sufficient mounting space is required. However, it is not always easy to secure the rigidity of the chain cover in consideration of the arrangement of the VVT drive unit in the chain cover.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine chain cover structure capable of accurately and compactly mounting a VVT.

An engine chain cover structure of the present invention includes a camshaft on each of an intake side and an exhaust side, a cam timing chain that drives these camshafts, and a cam on at least one of the intake side and exhaust side camshafts. A chain cover structure for an engine, comprising: a variable valve timing device that is mounted on an axial end portion of a shaft to change a cam timing; and a chain cover that covers the cam timing chain, the variable valve timing device comprising: It is configured to include a driven portion that is attached to an end portion and a driving portion that is held on the side of the chain cover and that drives the driven portion. The driven portion and the driving portion cooperate to change the cam timing. In the modification, the chain cover is formed with a bulging portion that bulges outward and a mount member mounting portion that mounts a mount member of an engine, and the bulging portion accommodates the variable valve timing device inside thereof. to thus formed Rutotomoni has an annular portion that holds the drive unit, the mounting member mounting portion is disposed adjacent to the bulging portion at the intake and exhaust direction, is coupled to the engine body A rib connecting the peripheral portion of the chain cover and the bulging portion is provided on the side opposite to the mount member mounting portion with the annular portion interposed therebetween, and a rib connecting the annular portion to the peripheral portion. characterized in that was.

According to the present invention, the mount member mounting portion can be arranged in a space-efficient manner, and the engine can be made compact.
Further, the surface rigidity of the chain cover can be significantly improved while the engine is made compact, and the deformation and the like due to the vibration of the engine can be effectively prevented.

It is the perspective view which looked at the engine for motor vehicles from diagonally right front as an example of application of the present invention. It is a figure which shows the state which looked at the engine from which the chain cover was removed in the embodiment of this invention from the front. It is the figure which looked at the engine from which the cylinder head cover was removed in the embodiment of the present invention from the upper part. It is the figure which looked at the cylinder head circumference from which the cylinder head cover was removed in the embodiment of the present invention from the front. It is the figure which looked at the cylinder head circumference from which the cylinder head cover was removed from the diagonally right upper front in an embodiment of the present invention. It is the figure which looked at the cylinder head circumference from which the cylinder head cover was removed in the embodiment of the present invention, and where the motor unit was attached from diagonally upper front. It is the figure which looked at the cylinder head circumference from which the cylinder head cover was removed in the embodiment of the present invention, and the motor unit was attached from diagonally left upper front.

Hereinafter, preferred embodiments of an engine chain cover structure according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a state in which an engine 10 for an automobile is viewed from a diagonally right front side as an application example of the present invention. First, a schematic configuration of an engine 10, which is an internal combustion engine, will be described with reference to FIG. In the drawings used in the following description, including FIG. 1, the direction from the transmission to the engine along the axial direction of the crankshaft is referred to as the front (indicated by arrow Fr), and the opposite direction is referred to as the rear, if necessary. (Indicated by arrow Rr). The direction perpendicular to the axis of the cylinder and the axis of the crankshaft is the right side (indicated by arrow R) and the left side is the left side (indicated by arrow L) when viewed from the rear. The arrangement direction of the engine 10 is not limited to the illustrated example, and can be appropriately selected according to the vehicle type and the like.

The engine 10 in this embodiment may be, for example, a multi-cylinder, typically a 3-cylinder DOHC gasoline engine or the like. In the engine 10, a cylinder head 13 and a cylinder head cover 14 are integrally coupled to the upper portion of a cylinder block 11 in order, and the cylinders are arranged in series (here, for example, No. 1 (#1, the same applies hereinafter) to The cylinder axis of (#3) is oriented in a substantially vertical direction. In the present embodiment, as shown in FIG. 1, the #1 to #3 cylinders are arranged in the front-rear direction, but they may be arranged in the left-right direction. An oil pan 15 that stores lubricating oil (engine oil) is integrally connected to the lower portion of the cylinder block 11. A cam timing chain, which will be described later, is mounted on the front side of the engine body of the engine 10, and a chain cover 16 covers the cam timing chain from the front.

Although not shown in the drawings, the engine 10 intakes air from the outside air to supply clean air (intake air) to the combustion chamber, intake system parts for supplying fuel, fuel system parts for supplying fuel, and after combustion in the cylinder. It has an exhaust system component for exhausting the exhaust gas from the engine 10. Further, it has a valve operating system component for driving and controlling the intake valve and the exhaust valve, a cooling system component for cooling the engine 10, and a lubricating system component for lubricating a movable part of the engine 10. Furthermore, a control system component (ECU; Engine Control Unit) for appropriately controlling the operation of each of these components in a predetermined sequence is attached. By the control of the control system parts, the plurality of functional system parts cooperate with the above-mentioned auxiliary machines and the like, whereby the engine 10 as a whole performs smooth operation.

Further, in FIG. 1, purified air is sent from the air cleaner to the intake manifold through the throttle valve, and the air is further supplied from the intake manifold to the intake port 17 of each cylinder (a part of which is shown in FIG. 1). ) Is supplied to. Further, the fuel in the fuel tank is supplied to the delivery pipe by the fuel pump, and the fuel is further supplied from the delivery pipe to the injector of each cylinder.

The engine 10 is suspended from a vehicle body frame of the vehicle (not shown) through a plurality of engine mounts (one of which is a mounting member 1 shown in FIG. 1) to be integrally coupled and supported to the vehicle body frame. Installed in the engine room of the vehicle. The engine 10 is mounted in the engine room, and the bonnet is attached to the engine room. Around the engine 10, there are arranged a plurality of auxiliary machines and the like, as well as a large number of devices or parts related thereto. It In this way, the engine 10 is arranged in an extremely small space in the engine room. It is extremely important in layout to arrange the engine 10 and its peripheral equipment and the like in a limited space in a space-efficient manner.

Further, as shown in FIG. 1, a crankshaft 18 (abbreviated by a chain line in FIG. 1) is rotatably supported in the crank chamber of the cylinder block 11. On the other hand, although not shown, a piston is fitted in the cylinder bore of each cylinder of the cylinder block 11 so as to be movable in the cylinder axis direction. The crankpin of the crankshaft 18 and the piston pin of the piston of each cylinder are connected to each other via a connecting rod, and the piston reciprocates in the cylinder bore along the cylinder axis direction, whereby the crankshaft 18 is rotationally driven. It is like this.

FIG. 2 is a diagram showing a state in which the engine 10 with the chain cover 16 removed is viewed from the front. A peripheral edge portion 10a formed over the area from the cylinder block 11 to the cylinder head 13 on the front surface side of the engine body of the engine 10 (indicated by hatching in FIG. 2. This area is basically a mating surface with the chain cover). The chain cover 16 is adapted to be joined. A cam timing chain chamber 19 is formed by being surrounded by the chain cover 16 and the front surface of the engine. Here, in the valve system of the engine 10, the cylinder head 13 has a cam shaft provided with cams for driving the intake valve and the exhaust valve of each cylinder. In the present embodiment, as shown in FIG. 2, the cylinder head 13 is rotatably rotatably supported, and includes intake side and exhaust side camshafts 20 and 21 arranged along the arrangement direction of the cylinders. These camshafts 20 and 21 are connected to the crankshaft 18 via a cam timing chain 25 as described later.

Further, FIG. 3 is a view of the engine 10 from which the cylinder head cover 14 is removed, as viewed from above. The shaft ends of the intake-side and exhaust-side camshafts 20 and 21 project into the cam timing chain chamber 19, and cam sprockets 22 and 23 as power transmission members are attached to these shaft ends. On the other hand, a crank sprocket 24 is attached to the shaft end of the crankshaft 18 as shown in FIG. 2, and a cam timing chain 25 is wound and mounted between the crank sprocket 24 and the cam sprockets 22 and 23. As shown in FIG. 2, the cam timing chain 25 runs along the crank sprocket 24 and the cam sprockets 22 and 23 while rotating clockwise (clockwise) when viewed from the front.

In the cam timing chain chamber 19, a chain tensioner for adjusting the tension of the cam timing chain 25, a tensioner adjuster 26, a chain guide 27, etc. are additionally provided. The drive system of the cam shafts 20 and 21, including the cam timing chain 25, the crank sprocket 24, and the cam sprockets 22 and 23, is housed in the cam timing chain chamber 19 covered by the chain cover 16.
In the present embodiment, the crank sprocket 24 and the cam sprockets 22 and 23 are connected via the cam timing chain 25. However, as an alternative to the cam timing chain 25, a timing belt or a timing pulley attached to the timing belt may be used. It is possible.

The intake-side camshaft 20 and the exhaust-side camshaft 21 are supported at the same height position in the cylinder head 13, and urge a tappet for opening and closing the valve for each cylinder. A cam 28 and a pair of cams 29 are provided. The tappet according to the present embodiment is a shim exchange type in which the valve clearance is adjusted by selecting and installing a proper thickness from a plurality of shims having different thicknesses. As described above, the crankshaft 18 and the cam sprockets 22 and 23 are connected via the cam timing chain 25 in the cam timing chain chamber 19. As the cam timing chain 25 runs by starting the engine, the camshafts 20 and 21 are rotationally driven by the rotation of the crankshaft 18 in the cylinder head 13. As a result, the cam 28 of the cam shaft 20 and the cam 29 of the cam shaft 21 open and close the intake valve and the exhaust valve at predetermined timings.

The engine 10 further includes a variable valve timing device 30 that changes the opening/closing timing of the valve driven by the cam 28 and the cam 29 to control the opening/closing phase with respect to the crank angle. This variable valve timing device 30 includes a driven portion attached to the shaft end portion of at least one of the intake side camshaft 20 and the exhaust side camshaft 21, and the chain cover 16 side. And a drive unit that drives the driven unit, and the cam timing is changed by the cooperation of the driven unit and the driving unit. In the present embodiment, the variable valve timing device 30 is attached to the intake side camshaft 20, but it may be attached to the exhaust side camshaft 21.

In the variable valve timing device 30, a cam phase conversion unit 31, which is a driven unit, is attached to the shaft end of the intake-side camshaft 20 to control the phase of the cam 28 when the cam 28 is opened and closed with respect to the crank angle. By driving the cam phase converter 31, the camshaft 20 changes the cam angle by changing the rotation angle of the camshaft 20 relative to the rotation angle of the crankshaft 18 toward the retard side or the advance side.

Here, the operation system of the variable valve timing device 30, in particular, its drive unit is, for example, a hydraulic system according to an aspect of the present invention. In this case, the cam phase of the cam 29 of the camshaft 21 can be advanced or retarded by hydraulic control by the hydraulic circuit for controlling the camshaft operation based on a command from the ECU in the drive unit of the variable valve timing device 30. ..
Further, according to another aspect of the present invention, the operation method of the drive unit in the variable valve timing device 30 is, for example, an electric method, that is, it is operated by the electric power of a vehicle-mounted battery. In this case, the drive unit is equipped with an electric motor, and the electric motor can rotate the rotation speed of the camshaft 20 faster or slower than the rotation speed of the cam sprocket 22, and similarly advance or retard the cam phase. it can.
In the present invention, both the hydraulic type and the electric type variable valve timing device 30 can be adopted, and either the hydraulic type or the electric type can be properly used according to the engine specifications or the like. Although an example of the electric variable valve timing device 30 will be described below, a hydraulic variable valve timing device 30 as an alternative thereto is also included in the scope of the present invention.

The chain cover 16 is equipped with a motor unit 32 that is a drive unit that is connected to and drives the cam phase conversion unit 31. The motor unit 32 has an electric motor for driving and a speed reduction mechanism, and the cam phase converter 31 cooperates with the motor unit 32 to advance the cam phase of the cam 28 in accordance with the rotation speed of the electric motor. Or, it has a function to retard. As an example of the operation of the variable valve timing device 30, the cam of the cam 28 is rotated by rotating the rotation speed of the cam shaft 20 faster than the rotation speed of the cam sprocket 22 by an electric motor of the motor unit 32 based on a command from the ECU. The phase is advanced. On the contrary, by decelerating the rotation speed of the cam shaft 20, the cam phase of the cam 28 is retarded.

As described above, the variable valve timing device 30 includes the cam phase converter 31 that is a driven portion and the motor unit 32 that is a driving portion, and applies a driving force from the driving portion having the electric motor and the speed reduction mechanism to the driven portion. It is an electric type that transmits.

In the chain cover 16 to which the variable valve timing device 30 is attached, a bulging portion 33 that accommodates the cam phase conversion portion 31 inside is formed by bulging forward from the chain cover 16 with reference to FIGS. 4 to 7. It 4 is a front view of the cylinder head 13 with the cylinder head cover 14 removed. FIG. 5 is a view of the cylinder head 13 from which the cylinder head cover 14 has been removed, as viewed from the diagonally upper right front side. FIG. 6 is a view of the cylinder head 13 with the cylinder head cover 14 removed and the motor unit 32 mounted, viewed obliquely from the upper front. FIG. 7 is a diagram of the cylinder head 13 around which the cylinder head cover 14 is removed and the motor unit 32 is mounted, as viewed from diagonally left upper front.

Here, referring to FIG. 3 and the like, the chain cover 16 includes a peripheral edge portion 16a which is aligned and joined to the peripheral edge portion 10a formed on the front surface side of the engine body over the region from the cylinder block 11 to the cylinder head 13. Inside the peripheral edge portion 16a, there is a cover portion 16b forming a cam timing chain chamber 19 (see FIG. 3). The chain cover 16 has a generally shallow concave shape in a general cross section along a direction orthogonal to the cylinder axis, as also indicated by a thick broken line in FIG. The peripheral edge portions 16a are provided on the left and right sides of the cover portion 16b along substantially the vertical direction. The bulging portion 33 corresponds to the intake-side camshaft 20 and protrudes forward from the cover portion 16b corresponding to the exhaust-side camshaft 21 so as to be raised by one step. In FIG. 3, the amount of protrusion A of the bulging portion 33 from the cover portion 16b is set. The protrusion of the bulging portion 33 allows the cam phase converter 31 and the motor unit 32 to be mounted, and functions as a mounting portion for the variable valve timing device 30.

As shown in FIGS. 4 and 5, the bulging portion 33 has an annular portion 35 having an opening 34 into which the motor unit 32 is fitted. The opening 34 is formed as a cylindrical surface coaxial with the intake-side camshaft 20, and the motor unit 32 has a cylindrical portion that is inserted into the opening 34, that is, the annular portion 35 holds the motor unit 32 by the inner opening 34. .. The upper edge 16c of the chain cover 16 and the upper edge 13a of the cylinder head 13 are flush with each other, and the center of the opening 34 coaxial with the camshaft 20 on the intake side coincides with the upper edge 16c of the chain cover 16 in the vertical direction. .. The upper half of the annular portion 35 is formed so as to project upward from the upper edge 16c of the chain cover 16. The cylinder head cover 14 is formed so as to be joined to the upper end edge 16c of the chain cover 16 and the upper end edge 13a of the cylinder head 13 including the upper half of the annular portion 35 without any gap. In this case, the cylinder head cover 14 joined to the upper edge 16c of the chain cover 16 forms the upper part of the cam timing chain chamber 19, that is, functions as a chain cover. In the present embodiment, the cylinder head cover 14 is typically made of synthetic resin, but it may be made of aluminum alloy or the like.

A plurality of mount members for mounting the engine 10 on the vehicle body frame are used, and the chain cover 16 is provided with a mount member mounting portion 36 to which one mount member (engine mount member) is mounted. Here, referring to FIG. 1, the mount member 1 is attached to the mount member attachment portion 36 as in the illustrated example, and the engine 10 is coupled to the vehicle body frame via the mount member 1. In addition to the mount member 1, a plurality of engine mounts including a transmission and the like are set. In this example, the mount member mounting portion 36 is arranged on the exhaust side of the engine 10 and protrudes from the cover portion 16b on the exhaust side in the same direction as the bulging portion 33 (that is, the front side). It is set to be appropriately smaller than the protrusion amount A. As shown in FIG. 4 and the like, the mount member mounting portion 36 occupies about 1/2 of the width of the chain cover 16 in the left-right direction, and extends in the left-right direction so as to connect the peripheral edge portion 16 a and the bulging portion 33. To be done. The upper surface of the mount member attaching portion 36 is formed as a flat fastening seat surface 36a for fastening the mount member 1, and a screw portion 37 (female screw) with which a fastening bolt for fixing the mount member 1 is screwed at the fastening seat surface 36a. ) Has been formed.

Further, as shown in FIG. 4 and the like, the mount member attaching portion 36 is formed at a height position lower than the annular portion 35 in the vertical direction. In this example, as shown in FIG. 4 or FIG. 6, the fastening seat surface 36a of the mount member mounting portion 36 is set lower than the upper end edge 16c of the chain cover 16 and has a cylindrical surface forming the opening 34 of the annular portion 35. It is formed at a position lower than the center (the axis of the camshaft 20 on the intake side). That is, the right end portion of the mount member attachment portion 36 is connected to the bulging portion 33 at a height position lower than the center of the opening 34 of the annular portion 35, and the annular portion 35 protruding upward from the upper end edge 16c of the chain cover 16. It is not connected to the upper half side of.

Further, as shown in FIGS. 5 and 6, a rib 38 connecting the annular portion 35 to the peripheral edge portion 16a is provided on the side opposite to the mount member mounting portion 36 in the left-right direction with respect to the annular portion 35. The rib 38 is flush with the upper edge 16c of the chain cover 16 in the peripheral edge portion 16a, and the cylinder head cover 14 is joined to the rib 38 without a gap.

In the above case, when the variable valve timing device 30 is mounted on the engine 10, the motor unit 32 is attached to the annular portion 35 in which the opening 34 is opened in the bulging portion 33 as shown in FIG. 4 or 5. Is inserted into the opening 34 from the front. As a method of fixing the motor unit 32, the motor unit 32 can be fixed by fastening the motor unit 32 fitted in the opening 34 to the annular portion 35 with a plurality of fastening bolts (not shown). The annular portion 35 is formed with a plurality of screw portions (female screws) (not shown) into which the fastening bolts are screwed. As shown in FIG. 3 and the like, the output shaft 32a of the motor unit 32 extends toward the cam phase conversion unit 31 side and is connected thereto.

In the engine 10 according to the present embodiment, as the cam timing chain 25 travels, the camshafts 20 and 21 are rotationally driven in the cylinder head 13 in synchronization with the rotation of the crankshaft 18. As a result, the cam 28 of the cam shaft 20 and the cam 29 of the cam shaft 21 open and close the intake valve and the exhaust valve at predetermined timings.

In the present embodiment, the variable valve timing device 30 changes the phase of the cam 28 of the intake side camshaft 20 according to the operating state of the engine 10. That is, the electric motor of the motor unit 32 drives the cam phase conversion unit 31 to appropriately advance or retard the opening/closing phase of the cam 28. Note that electric power from a vehicle-mounted battery or the like can be used as a drive power source for the motor unit 32. Since the variable valve timing device 30 is of an electric type, it has advantages such as speedy and accurate operation.

Next, the main function and effect of the engine chain cover structure of the present invention will be described. In the present embodiment, the variable valve timing device 30 is mounted on the intake side of the engine 10, and a bulging portion 33 that accommodates the variable valve timing device 30 is provided. The mount member mounting portion 36 is arranged in the space on the exhaust side of the bulging portion 33. First, by effectively utilizing the space on the exhaust side of the chain cover 16 in this manner, the mount member mounting portion 36 can be arranged in a narrow space with good space efficiency.

In this case, the mount member mounting portion 36 is arranged on the exhaust side of the engine 10 and projects from the cover portion 16b of the chain cover 16 in the same direction as the bulging portion 33. The mount member attachment portion 36 is extended in the left-right direction so as to connect the peripheral edge portion 16 a of the chain cover 16 and the bulging portion 33. That is, the mount member attachment portion 36 does not simply project from the surface of the cover portion 16b of the chain cover 16, but has the bulging portion 33 on one end side extending in the left-right direction and the peripheral edge portion 16a on the other end side. The three-dimensional structure is constructed in the cover portion 16b by being combined with each other and coupled with the bulging portion 33. As a result, the surface rigidity of the chain cover 16 is greatly improved, so that a large load required to support the engine 10 via the mount member 1 (FIG. 1) can be reliably received. Further, it is possible to effectively prevent the chain cover 16 from being deformed due to the load when the engine 10 vibrates. On the other hand, in the past, it was not easy to secure the surface rigidity of the chain cover when the chain cover receives a load when the engine vibrates. Further, since the surface rigidity of the chain cover 16 is improved, the surface vibration during the operation of the engine 10 is suppressed, and the resulting noise is effectively prevented.

Further, the bulging portion 33 has an annular portion 35 that holds a motor unit 32 that is a drive portion of the variable valve timing device 30, and the motor unit 32 is located outside the axial end portion of the intake-side camshaft 20. It can be inserted into the annular portion 35.
When the variable valve timing device 30 is incorporated in the engine 10, the motor unit 32 can be easily and accurately inserted into the opening 34 of the annular portion 35 from the front of the opening 34, and the assembling property is excellent. .. In that case, by fastening and fixing the motor unit 32 to the annular portion 35 with the fastening bolt, the motor unit 32 itself functions as a rigid member, and the rigidity of the annular portion 35 can be increased.

Further, the mount member mounting portion 36 of the mount member 1 is formed at a height position lower than the annular portion 35 in the vertical direction.
As described above, the mount member mounting portion 36 is connected to the bulging portion 33, and thus the annular portion 35, at one end side in the left-right direction, and the load that the mount member mounting portion 36 receives when the engine 10 vibrates is indirectly. Is also transmitted to the annular portion 35. The upper half of the annular portion 35 projects upward from the upper edge 16c of the chain cover 16, while the lower half of the annular portion 35 is integrally formed with the cover portion 16b of the chain cover 16. .. The mount member attachment portion 36 is joined at least at a position lower than the center of the annular portion 35, and the mount member attachment portion 36 is joined at a portion of the annular portion 35 having higher rigidity. This reduces the influence of the load when the engine 10 vibrates on the annular portion 35 via the mount member attaching portion 36. The deformation of the annular portion 35 is suppressed, and the annular portion 35 can hold the motor unit 32 while ensuring proper operation of the motor unit 32, and thus realizes proper and smooth operation of the variable valve timing device 30. can do.

Further, a rib 38 that connects the annular portion 35 to the peripheral edge portion 16a is provided on the side opposite to the mount member attaching portion 36 (on the right side in this example) with the annular portion 35 interposed therebetween.
By connecting the chain cover 16 to the engine body of the engine 10, the peripheral edge portion 16a (right side) whose rigidity is enhanced and the annular portion 35 are connected by the rib 38, and the joint rigidity can be further enhanced. it can. Further, by coupling the ring member 35 to the mount member mounting portions 36 and the ribs 38 on both sides in the left-right direction, this also contributes to the improvement of the surface rigidity of the chain cover 16.

Further, the mount member mounting portion 36 is set so that the protrusion amount A′ from the chain cover 16 is smaller than the bulging portion 33 (protrusion amount A).
The mount member attachment portion 36 improves the surface rigidity of the chain cover 16 and also suppresses the protrusion from the chain cover 16 as much as possible to achieve a compact size.

Here, in the present invention, as a modification of the above-described embodiment, for example, in addition to the case where the annular portion 35 is integrally formed with the chain cover 16, the cylinder head cover 14 and the chain cover 16 may be formed in an upper and lower half structure. It is possible.
Further, the variable valve timing device 30 can be attached to the exhaust side camshaft 21 as in the case of the intake side.

Although the present invention has been described above with various embodiments, the present invention is not limited to these embodiments, and modifications and the like can be made within the scope of the present invention.
For example, although the example of the three-cylinder gasoline engine has been described in the above embodiment, the engine may be a two-cylinder engine, a four-cylinder engine, or the like.

10 engine, 11 cylinder block, 13 cylinder head, 14 cylinder head cover, 15 oil pan, 16 chain cover, 17 intake port, 18 crankshaft, 19 cam timing chain chamber, 20 intake side camshaft, 21 exhaust side camshaft , 22, 23 cam sprocket, 24 drive sprocket, 25 cam timing chain, 26 chain tensioner and tensioner adjuster, 27 chain guide, 28, 29 cam, 30 variable valve timing device, 31 cam phase converter, 32 motor unit, 33 expansion Projection part, 34 opening, 35 annular part, 36 mount member mounting part, 38 rib.

Claims (5)

Intake-side and exhaust-side camshafts, a cam timing chain that drives these camshafts, and a cam attached to the shaft end portion of at least one of the intake-side and exhaust-side camshafts. A chain cover structure for an engine, comprising: a variable valve timing device for changing timing; and a chain cover for covering the cam timing chain,
The variable valve timing device includes a driven portion attached to the shaft end portion and a driving portion that is held on the chain cover side and drives the driven portion, and the driven portion and the driving portion. Change the cam timing with the cooperation of
The chain cover is formed with a bulging portion that bulges outward and a mount member mounting portion that mounts a mount member of the engine,
The bulging portion has an annular portion for holding Rutotomoni formed to accommodate the variable valve timing device on the inside, the drive unit,
The mount member mounting portion is disposed adjacent to the bulging portion in the intake/exhaust direction, and connects the peripheral portion of the chain cover coupled to the engine body and the bulging portion ,
A chain cover structure for an engine, wherein a rib connecting the annular portion to the peripheral portion is provided on the side opposite to the mount member mounting portion with the annular portion interposed therebetween . The bulging portion, the chain cover structure for an engine according to claim 1, before Symbol driving unit, characterized in that from the outside of the shaft end portion is insertable into the annular portion. The engine chain cover structure according to claim 1 or 2 , wherein the mount member attachment portion is formed to be lower than a center of the annular portion in a vertical direction. The variable valve timing apparatus, the chain for an engine according to any one of claims 1 to 3, characterized in that a motorized for transmitting a driving force to the driven portion from said drive unit having an electric motor Cover structure. The mounting member mounting portion, the chain cover structure for an engine according to any one of claims 1 to 4, the projecting amount from the chain cover is characterized in that it is smaller than the bulged portion.

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