JP7613293B2 - Cover structure for internal combustion engine - Google Patents

Description

The present invention relates to a cover structure for an internal combustion engine.

Internal combustion engines mounted on vehicles are provided with hydraulic variable devices for varying the valve timing of the intake and exhaust valves, and one such variable device is known that is attached to the chain case (see Patent Document 1).

This chain case has a first mounting hole to which the intake side variable device is attached, and a second mounting hole to which the exhaust side variable device is attached.

When the direction from the outer surface of the chain case toward the inner surface facing the engine body is defined as the depth direction, a step is provided between the first mounting surface on the outer surface of the chain case, on which the first mounting hole is provided, and the second mounting surface on which the second mounting hole is provided, which makes the depth position of the first mounting surface different from the depth position of the second mounting surface, and this step increases the rigidity of the chain case having the first and second mounting holes.

JP 2016-217327 A

Some chain cases have a mount attachment section for supporting the engine body on the vehicle body. The mount attachment section is an outward protrusion from the top of the chain case, and the upper wall of the mount attachment section has bolt holes for attaching a mounting member such as a mounting bracket.

In the stepped chain case described in Patent Document 1, if mount attachment parts are installed below the first and second attachment surfaces, the following problems may occur.

The first and second mounting surfaces are at different distances from the engine body, and the distance from the bolt hole of the mount attachment portion to the second mounting surface is longer than the distance from the bolt hole of the mount attachment portion to the first mounting surface.

As a result, when a vertical load acts on the bolt hole, the moment acting on the lower end of the second mounting surface is greater than that acting on the lower end of the first mounting surface, and the portion of the mount mounting part facing the second mounting surface may vibrate more in the vertical direction of the vehicle than the portion of the mount mounting part facing the first mounting surface.

The present invention was made with a focus on the above problems, and aims to provide a cover structure for an internal combustion engine that can suppress vibration of the mount attachment part in a cover member in which a first vertical wall part and a second vertical wall part that are at different distances from the internal combustion engine body are installed in parallel on the top of the mount attachment part.

The present invention provides a first camshaft and a second camshaft that are rotatably supported on an internal combustion engine body with their axial directions parallel to each other and to which power is transmitted from a crankshaft via a transmission member, a first valve timing adjustment device attached to an end of the first camshaft and a second valve timing adjustment device attached to an end of the second camshaft, and a cover member attached to an end of the internal combustion engine body so as to cover the first valve timing adjustment device, the second valve timing adjustment device, and the transmission member, the cover member comprising a first vertical wall portion that covers the first valve timing adjustment device, and a second vertical wall portion that covers the second valve timing adjustment device and is disposed closer to the internal combustion engine body than the first vertical wall portion. A cover structure for an internal combustion engine, comprising a mount attachment portion located below the first vertical wall portion and the second vertical wall portion and bulging away from the internal combustion engine body relative to the cover member, and a fastening portion for fastening a mount member that supports the internal combustion engine body to a vehicle body is provided at the tip of the upper wall of the mount attachment portion in the bulging direction, the cover member has a first connecting portion that connects the upper wall to the lower end of the first vertical wall portion and a second connecting portion that connects the upper wall to the lower end of the second vertical wall portion, and the second connecting portion bulges upward in a step shape from the upper wall at a position adjacent to the end of the first connecting portion on the fastening portion side in the axial direction of the second camshaft and is connected to the second vertical wall portion.

In this way, according to the present invention, vibrations of the mount attachment part can be suppressed in a cover member in which a first vertical wall part and a second vertical wall part, which are disposed in parallel on the upper part of the mount attachment part and are at different distances from the internal combustion engine body.

FIG. 1 is a front view of an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a top view of the internal combustion engine according to one embodiment of the present invention, showing a state in which the cylinder head cover has been removed. FIG. 3 is a perspective view of a chain cover for an internal combustion engine according to one embodiment of the present invention. FIG. 4 is an enlarged front view of an upper portion of a chain cover of an internal combustion engine according to one embodiment of the present invention. FIG. 5 is a top view of the chain cover as viewed in the direction of arrow V in FIG. FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG.

A cover structure for an internal combustion engine according to one embodiment of the present invention includes a first camshaft and a second camshaft that are rotatably supported on the internal combustion engine body with their axial directions parallel to each other and to which power is transmitted from the crankshaft via a transmission member, a first valve timing adjustment device attached to an end of the first camshaft and a second valve timing adjustment device attached to an end of the second camshaft, and a cover member attached to an end of the internal combustion engine body so as to cover the first valve timing adjustment device, the second valve timing adjustment device, and the transmission member, and the cover member has a first vertical wall portion that covers the first valve timing adjustment device, and a second valve timing adjustment device that covers the second valve timing adjustment device and is located inwardly of the first vertical wall portion. A cover structure for an internal combustion engine, which includes a second vertical wall portion installed on the engine body side, and a mount attachment portion located below the first vertical wall portion and the second vertical wall portion and bulging away from the engine body relative to the cover member, and a fastening portion for fastening a mount member that supports the engine body on a vehicle body is provided at the tip of the upper wall of the mount attachment portion in the bulging direction, and the cover member has a first connecting portion that connects the upper wall to the lower end of the first vertical wall portion and a second connecting portion that connects the upper wall to the lower end of the second vertical wall portion, and the second connecting portion bulges upward in a stepped manner from the upper wall at a position adjacent to the end of the first connecting portion on the fastening portion side in the axial direction of the second camshaft, and is connected to the second vertical wall portion.

As a result, the cover structure for an internal combustion engine according to one embodiment of the present invention can suppress vibration of the mount attachment part in a cover member in which a first vertical wall part and a second vertical wall part, which are disposed in parallel on the upper part of the mount attachment part and are at different distances from the internal combustion engine body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a cover structure for an internal combustion engine according to the present invention will be described with reference to the drawings.
1 to 8 are diagrams showing a cover structure for an internal combustion engine according to one embodiment of the present invention. In Fig. 1 to Fig. 8, the up, down, front, rear, left and right directions are defined as follows.

The direction along the crankshaft is the front-to-rear direction of the engine, with the side where the timing chain is located being the front and the opposite side being the rear. The direction along the central axis of the cylinder is the up-down direction of the engine, with the cylinder head side being the top and the opposite side being the bottom. The direction that intersects with the crankshaft and the central axis of the cylinder is the left-to-right direction of the engine, with the left side of the central axis of the cylinder when looking at the crankshaft from the rear being the left and the right side of the central axis of the cylinder being the right.

First, the configuration will be described.
1, an engine 1 includes an engine body 2 and a chain cover 40. The engine body 2 includes a cylinder block 3, a cylinder head 4, a cylinder head cover 5, and an oil pan 6. The engine 1 of this embodiment constitutes an internal combustion engine, and the engine body 2 constitutes an internal combustion engine body.

The cylinder block 3 has multiple cylinders (not shown), which are arranged in a line in the front-to-rear direction of the engine 1. The engine 1 is installed so that the central axis 1C of the cylinder extends in the vertical direction.

Each cylinder houses a piston (not shown), and the pistons are connected to the crankshaft 7 via a connecting rod (not shown). The crankshaft 7 has a central axis of rotation that extends in the front-to-rear direction and rotates around the central axis of rotation.

The pistons reciprocate within the cylinders, rotating the crankshaft 7 via the connecting rod. The cylinder head 4 has multiple intake ports and multiple exhaust ports (not shown).

The intake ports are connected to the cylinders and introduce intake air into the cylinders. The exhaust manifold is connected to multiple cylinders through exhaust ports, and collects exhaust gases discharged from the multiple cylinders and discharges them from the exhaust port to a catalytic converter (not shown).

As shown in FIG. 2, the intake camshaft 11 and the exhaust camshaft 12 are rotatably supported in the cylinder head 4. The intake camshaft 11 and the exhaust camshaft 12 are installed side by side in the left-right direction of the engine 1 with their rotational center axes 11a and 12a extending parallel to the front-rear direction of the engine 1.

The intake camshaft 11 has multiple intake cams 11A (two shown), which are arranged side by side in the direction of the rotational center axis 11a of the intake camshaft 11.

For example, two intake cams 11A are provided for each cylinder. An intake valve (not shown) is provided in the intake port, and the intake cam 11A operates the intake valve to open and close the intake port, thereby connecting or blocking the cylinder and the intake port.

The exhaust camshaft 12 is equipped with multiple exhaust cams 12A (two in the figure), and the exhaust cams 12A are arranged side by side in the direction of the rotation center axis 12a of the exhaust camshaft 12. Hereinafter, the direction of the rotation center axes 11a, 12a is referred to as the axial direction.

For example, two exhaust cams 12A are provided for each cylinder. An exhaust valve (not shown) is provided in the exhaust port, and the exhaust cam 12A operates the exhaust valve to open and close the exhaust port, connecting or blocking the cylinder and the exhaust port.

The intake side valve timing adjustment device 15 is attached to the axial front end (end) of the intake camshaft 11. The intake side valve timing adjustment device 15 has an intake side housing member 23, and an intake sprocket 23S is provided on the outer periphery of the intake side housing member 23.

An exhaust valve timing adjustment device 16 is attached to the axial front end (end) of the exhaust camshaft 12. The exhaust valve timing adjustment device 16 has an exhaust housing member 24, and an exhaust sprocket 24S is provided on the outer periphery of the exhaust housing member 24.

The length of the intake side housing member 23 in the axial direction of the intake camshaft 11 and the exhaust camshaft 12 is longer than the length of the exhaust side housing member 24.

As shown in FIG. 1, a crank sprocket 7S is provided at the front end of the crankshaft 7. A timing chain 8 is wound around the crank sprocket 7S, the intake sprocket 23S, and the exhaust sprocket 24S.

In this embodiment, the timing chain 8 constitutes a transmission member. The intake valve timing adjustment device 15 constitutes a first valve timing adjustment device, and the exhaust valve timing adjustment device 16 constitutes a second valve timing adjustment device.

The intake side valve timing adjustment device 15 may be configured from a second valve timing adjustment device, and the exhaust side valve timing adjustment device 16 may be configured from a first valve timing adjustment device.

The power of the crankshaft 7 is transmitted to the intake camshaft 11 and the exhaust camshaft 12 via the timing chain 8. As a result, the intake camshaft 11 rotates and the intake cam 11A opens and closes the intake valve, and the exhaust camshaft 12 rotates and the exhaust cam 12A opens and closes the exhaust valve.

The intake valve timing adjustment device 15 adjusts the relative rotational phase of the intake camshaft 11 with respect to the crankshaft 7, and adjusts the opening and closing timing (valve timing) of the intake valves.

The exhaust valve timing adjustment device 16 adjusts the relative rotational phase of the exhaust camshaft 12 with respect to the crankshaft 7 to adjust the opening and closing timing (valve timing) of the exhaust valve. In this embodiment, the intake camshaft 11 constitutes the first camshaft, and the exhaust camshaft 12 constitutes the second camshaft. Note that the intake camshaft 11 may be composed of the second camshaft, and the exhaust camshaft 12 may be composed of the first camshaft.

An oil pump 35 is provided in the cylinder block 3. The oil pump 35 is driven by the crankshaft 7 to supply oil stored in the oil pan 6 to each part of the engine 1.

The chain cover 40 is attached to the front end (end) of the cylinder block 3 and the front end (end) of the cylinder head 4.

The chain cover 40 is formed so that the vertical direction of the chain cover 40 is longer than the horizontal direction of the chain cover 40, so that the direction along the vertical direction of the engine 1 is the longitudinal direction and the direction along the horizontal direction of the engine 1 is the transverse direction. As shown in Figures 2 and 5, the chain cover 40 has a vertical wall 41, a left side wall portion 42, and a right side wall portion 43.

The vertical wall 41 faces the front end of the cylinder block 3 and the cylinder head 4 in the axial direction of the intake camshaft 11 and the exhaust camshaft 12.

The left side wall 42 and the right side wall 43 protrude from the right and left ends of the width (short side) of the chain cover 40 toward the engine body 2, and the leading ends in the protruding direction are fastened to the front end of the cylinder block 3 and the front end of the cylinder head 4 by multiple bolts 33A (see FIG. 1). In this way, the chain cover 40 is fixed to the engine body 2.

As shown in FIG. 2, the chain cover 40 houses the timing chain 8, the intake valve timing adjustment device 15, and the exhaust valve timing adjustment device 16, and covers the timing chain 8, the intake valve timing adjustment device 15, and the exhaust valve timing adjustment device 16 from the front.

In Figures 1 and 2, the timing chain 8 is shown by a phantom line. In this embodiment, the chain cover 40 constitutes a cover member. Note that the phantom line 55 in Figures 1 and 4 is the boundary between the cylinder block 3 and the cylinder head 4.

The power of the crankshaft 7 is transmitted to the intake side housing member 23 of the intake side valve timing adjustment device 15 via the timing chain 8.

The intake side housing member 23 houses an intake side vane rotor (not shown), which rotates integrally with the intake camshaft 11. The intake side vane rotor divides the inside of the intake side housing member 23 into multiple advance chambers and multiple retard chambers (not shown).

The intake valve timing adjustment device 15 is provided with an intake spool valve 25 (see Figure 2). The intake spool valve 25 rotates integrally with the intake camshaft 11 and is movable in the axial direction of the intake camshaft 11.

The power of the crankshaft 7 is transmitted to the exhaust side housing member 24 of the exhaust side valve timing adjustment device 16 via the timing chain 8.

The exhaust side housing member 24 houses an exhaust side vane rotor (not shown), which rotates integrally with the exhaust camshaft 12. The exhaust side vane rotor divides the interior of the exhaust side housing member 24 into multiple advance chambers and multiple retard chambers (not shown).

The exhaust valve timing adjustment device 16 is provided with an exhaust spool valve 26 (see FIG. 2). The exhaust spool valve 26 is installed on the rotation center axis 12a of the exhaust camshaft 12 so as to rotate integrally with the exhaust camshaft 12, and is freely movable in the axial direction of the exhaust camshaft 12.

As shown in Figures 2 and 3, the upper part of the vertical wall 41 of the chain cover 40 is provided with an intake side vertical wall portion 41A and an exhaust side vertical wall portion 41B, and the intake side vertical wall portion 41A and the exhaust side vertical wall portion 41B are installed in parallel in the width direction (short direction) of the chain cover 40.

The intake side vertical wall portion 41A faces the intake side valve timing adjustment device 15 in the axial direction of the intake camshaft 11 and covers the intake side valve timing adjustment device 15.

The exhaust side vertical wall portion 41B faces the exhaust side valve timing adjustment device 16 in the axial direction of the exhaust camshaft 12 and covers the exhaust side valve timing adjustment device 16.

The exhaust side vertical wall portion 41B is recessed toward the engine body 2 relative to the intake side vertical wall portion 41A. In other words, the exhaust side vertical wall portion 41B is recessed toward the engine body 2 relative to the intake side vertical wall portion 41A, and the intake side vertical wall portion 41A bulges away from the engine body 2 relative to the exhaust side vertical wall portion 41B.

The intake side vertical wall portion 41A and the exhaust side vertical wall portion 41B are connected by a step portion 41C having a step in the axial direction of the intake camshaft 11. In other words, the intake side vertical wall portion 41A and the exhaust side vertical wall portion 41B are separated in the axial direction of the intake camshaft 11 and the exhaust camshaft 12 by the step portion 41C.

As shown in Figures 1 and 2, the chain cover 40 is provided with an intake solenoid 31 and an exhaust solenoid 32.

As shown in Figures 1 and 4, the intake side vertical wall portion 41A has an intake side through hole 41a into which the intake side solenoid 31 is inserted. The intake side solenoid 31 is attached to the intake side through hole 41a, and the intake side solenoid 31 is fixed to the intake side vertical wall portion 41A by a bolt (not shown).

The exhaust side vertical wall portion 41B has an exhaust side through hole 41b into which the exhaust side solenoid 32 is inserted. The exhaust side solenoid 32 is attached to the exhaust side through hole 41b, and the exhaust side solenoid 32 is fixed to the exhaust side vertical wall portion 41B by a bolt (not shown).

In this embodiment, the intake side vertical wall portion 41A constitutes the first vertical wall portion, and the exhaust side vertical wall portion 41B constitutes the second vertical wall portion. Note that the intake side vertical wall portion 41A may be constituted by the second vertical wall portion, and the exhaust side vertical wall portion 41B may be constituted by the first vertical wall portion.

The intake side solenoid 31 operates the intake side spool valve 25 so that the intake side spool valve 25 moves in the axial direction of the intake camshaft 11.

When the intake solenoid 31 moves to the advance chamber position in the axial direction of the intake valve timing adjustment device 15, oil is supplied from the oil pump 35 to the advance chamber.

When oil is supplied to the advance chamber, the intake vane rotor rotates relative to the intake housing member 23, adjusting the relative rotation phase of the intake camshaft 11 to the crankshaft 7 to the advance side, and adjusting the opening and closing timing of the intake valve to the advance side.

When the intake solenoid 31 moves toward the retard side in the axial direction of the intake camshaft 11, oil is supplied from the oil pump 35 to the retard chamber.

When oil is supplied to the retard chamber, the intake vane rotor rotates relative to the intake housing member 23, adjusting the relative rotational phase of the intake camshaft 11 to the crankshaft 7 to a retarded angle, and adjusting the opening and closing timing of the exhaust valve to the retarded side.

The exhaust spool valve 26 is operated by the exhaust solenoid 32, and similarly to the intake valve timing adjustment device 15, it supplies oil to either the advance or retard chamber to adjust the relative rotational phase of the exhaust camshaft 12 to the crankshaft 7 to the advance or retard side, and adjusts the opening and closing timing of the exhaust valve to the advance or retard side. The intake solenoid 31 of this embodiment constitutes the first operating member of the present invention, and the exhaust solenoid 32 constitutes the second operating member.

As shown in Figures 3 and 4, a mount attachment portion 44 is provided on the upper part of the vertical wall 41 of the chain cover 40.

The mount attachment portion 44 is located below the intake side vertical wall portion 41A and the exhaust side vertical wall portion 41B, and bulges out in a direction away from the engine body 2 relative to the chain cover 40, i.e., forward.

As shown in FIG. 6, a side member 9 is provided in front of the engine 1, and the side member 9 extends in the fore-and-aft direction of the vehicle.

As shown in FIG. 3, the tip of the mount attachment portion 44 is provided with a mounting seat 44a, and the mounting seat 44a is provided with mount bosses 44b, 44c, and 44d. The inner circumferential surfaces of the mount bosses 44b, 44c, and 44d are formed with bolt holes 44r, 44s, and 44t through which bolts are inserted.

As shown in FIG. 6, a mount member 51 is attached to the mounting seat 44a. The mount member 51 has a mount bracket 51A, and a bolt is inserted into the rear end of the mount bracket 51A.

The bolt inserted into the rear end of the mount bracket 51A is inserted into the bolt holes 44r, 44s, and 44t, and then fastened to a nut (not shown). This fastens the rear end of the mount bracket 51A to the mounting seat 44a.

The mount member 51 is equipped with a vibration absorbing member 51B, which is attached to the side member 9. The front end of the mount bracket 51A is attached to the vibration absorbing member 51B, and the engine body 2 is elastically supported on the side member 9 via the mount member 51.

As a result, the vibrations of the engine 1 can be absorbed by the mount member 51, and the vibrations transmitted from the engine 1 to the side member 9 can be suppressed. In this embodiment, the side member 9 constitutes the vehicle body.

As shown in FIG. 3, the mount attachment portion 44 has an upper wall 44A, a peripheral wall 44B, and a lower wall 44C. The upper wall 44A extends linearly forward from the vertical wall 41, and the attachment seat 44a is provided at the tip of the upper wall 44A in the bulging direction.

The peripheral wall 44B extends downward from the outer periphery of the upper wall 44A. The lower wall 44C curves upward from the vertical wall 41 below the mount attachment portion 44 so as to gradually move away from the vertical wall 41, and its upper end is connected to the tip of the peripheral wall 44B in the bulging direction (see Figures 6, 7, and 8).

Mount bosses 44b, 44c, and 44d extend from mounting seat 44a to bottom wall 44C. In this embodiment, mount bosses 44b, 44c, and 44d include bolt holes 44r, 44s, and 44t.

As shown in FIG. 5, the length A of the mount attachment portion 44 from the lower end of the intake side vertical wall portion 41A to the mount bosses 44b and 44d is shorter than the length B of the mount attachment portion 44 from the lower end of the exhaust side vertical wall portion 41B to the mount bosses 44b and 44d.

That is, the mount attachment portion 44 has different lengths A and B relative to the chain cover 40 in the axial direction of the intake camshaft 11 and the exhaust camshaft 12, and the axial lengths of the intake camshaft 11 and the exhaust camshaft 12 are different. The upper wall 44A in this embodiment is configured to include the attachment seat 44a.

As shown in Figures 3, 7, and 8, the upper wall 44A is provided with an intake side connecting wall 44D and an exhaust side connecting wall 44E.

As shown in FIG. 7, the intake side connecting wall 44D connects the upper wall 44A to the lower end 41m of the intake side vertical wall portion 41A, and extends from the upper wall 44A to the lower end 41m of the intake side vertical wall portion 41A.

As shown in FIG. 8, the exhaust side connecting wall 44E connects the upper wall 44A and the lower end 41n of the exhaust side vertical wall portion 41B.

As shown in Figures 3 and 8, the exhaust side connecting wall 44E is installed below the exhaust side through hole 41b. As shown in Figures 3 and 5, the exhaust side connecting wall 44E bulges out in a step-like manner upward from the upper wall 44A at a position adjacent to the front end 44f, which is the end of the intake side connecting wall 44D on the mount boss 44b, 44c, and 44d side in the axial direction of the intake camshaft 11 and the exhaust camshaft 12, and is connected to the exhaust side vertical wall portion 41B.

Specifically, as shown in FIG. 5, the front end 44e of the exhaust-side connecting wall 44E is disposed adjacent to the front end 44f of the intake-side connecting wall 44D in the axial direction of the exhaust camshaft 12, and the exhaust-side connecting wall 44E bulges upward in a stepped manner from the upper wall 44A at a position close to the mounting bosses 44b, 44c, and 44d.

That is, the upper wall 44A of the mount attachment portion 44 is located forward of the front end portion 44f of the intake side connecting wall 44D and the front end portion 44e of the exhaust side vertical wall portion 41B.

As shown in FIG. 8, the exhaust side connecting wall 44E has an inclined wall 44g that extends obliquely upward from the upper wall 44A toward the exhaust side vertical wall portion 41B, and a top wall 44h that bends horizontally from the rear end portion 44i (end portion) in the direction in which the inclined wall 44g extends and extends below the exhaust side through hole 41b.

The mount bosses 44b, 44c, and 44d in this embodiment form the fastening portion. The intake side connecting wall 44D in this embodiment forms the first connecting portion, and the exhaust side connecting wall 44E forms the second connecting portion. Note that the intake side connecting wall 44D may be formed from the second connecting portion to form a bulging structure, and the exhaust side connecting wall 44E may be formed from the first connecting portion.

As shown in FIG. 4, the intake side through hole 41a and the exhaust side through hole 41b are formed so that the distance C from the lower end of the intake side through hole 41a to the upper wall 44A is longer than the distance D from the lower end of the exhaust side through hole 41b to the upper wall 44A.

As shown in FIG. 4, bosses 45A and 45B are provided on the vertical wall 41 of the chain cover 40. The boss 45A is provided in the center of the vertical wall 41 in the width direction, near the top wall 44A. Specifically, the boss 45A is provided between the intake side through hole 41a and the exhaust side through hole 41b and the top wall 44A in the up-down direction of the chain cover 40.

As shown in FIG. 6, the inner end 45a of the boss 45A is joined to the engine body 2, and the outer end 45b of the boss 45A protrudes forward (outward) from the stepped portion 41C. A bolt 33C (see FIG. 1) is inserted into the boss 45A, and the boss 45A is fastened to the engine body 2 by the bolt 33C. The bolt 33C in this embodiment constitutes a fastener.

As shown in FIG. 4, the boss 45B is located in the center of the vertical wall 41 in the width direction, below the mount attachment portion 44. As shown in FIG. 6, the inner end 45c of the boss 45B is joined to the engine body 2, and the outer end 45d of the boss 45B protrudes forward (outward) from the lower wall 44C.

Bolt 33D (see FIG. 1) is fastened to boss 45B, and boss 45B is fastened to engine body 2 by bolt 33D. In other words, chain cover 40 is fastened to engine body 2 by bolts 33A, 33C, and 33D.

As shown in Figures 3 and 4, the boss 45A is connected to the right end of the exhaust side connecting wall 44E, and its upper end is located above the top wall 44h of the exhaust side connecting wall 44E. In this embodiment, the boss 45A constitutes a central boss.

Next, the effect of the cover structure of the engine 1 according to this embodiment will be described.
The cover structure for the engine 1 in this embodiment includes a chain cover 40 attached to the front end of the engine body 2 so as to cover the intake side valve timing controller 15, the exhaust side valve timing controller 16 and the timing chain 8.

The chain cover 40 has an intake side vertical wall portion 41A that covers the intake side valve timing adjustment device 15, an exhaust side vertical wall portion 41B that covers the exhaust side valve timing adjustment device 16 and is installed closer to the engine body 2 than the intake side vertical wall portion 41A, and a mount attachment portion 44 that is located below the intake side vertical wall portion 41A and the exhaust side vertical wall portion 41B and bulges out in a direction away from the engine body 2 relative to the chain cover 40.

Mount bosses 44b, 44c, and 44d are provided at the tip of the upper wall 44A of the mount attachment portion 44 in the bulging direction to fasten the mount member 51 that supports the engine body 2 to the side member 9, and the chain cover 40 has an intake side connecting wall 44D that connects the upper wall 44A to the lower end 41m of the intake side vertical wall portion 41A, and an exhaust side connecting wall 44E that connects the upper wall 44A to the lower end 41n of the exhaust side vertical wall portion 41B.

In addition, the exhaust side connecting wall 44E bulges upward in a step shape from the upper wall 44A at a position adjacent to the front end 44f, which is the end of the intake side connecting wall 44D on the side of the mounting bosses 44b, 44c, and 44d in the axial direction of the exhaust camshaft 12, and is connected to the exhaust side vertical wall portion 41B.

Compared to the intake side connecting wall 44D, which connects the upper wall 44A of the mount attachment part 44 and the lower end 41n of the exhaust side vertical wall part 41B with a curved wall having a predetermined radius, the exhaust side connecting wall 44E can expand its cross section in the vertical direction, making it less likely to deform under vertical load. This increases the connection rigidity of the upper wall 44A of the mount attachment part 44 to the exhaust side vertical wall part 41B.

In addition, even if the length B of the mount attachment portion 44 from the lower end 41n of the exhaust side vertical wall portion 41B to the mount bosses 44b, 44d is made greater than the length A of the mount attachment portion 44 from the lower end 41m of the intake side vertical wall portion 41A to the mount bosses 44b, 44d, by making the exhaust side connecting wall 44E a highly rigid bulging structure, the connection rigidity of the upper wall 44A of the mount attachment portion 44 to the exhaust side vertical wall portion 41B can be made closer to the connection rigidity of the upper wall 44A of the mount attachment portion 44 to the intake side vertical wall portion 41A.

This allows the vertical load F (see Figure 6) applied to the mount attachment portion 44 from the mount member 51 when the engine 1 vibrates to be evenly distributed to the intake side connecting wall 44D and the exhaust side connecting wall 44E.

As a result, when a load F is applied in the vertical direction from the mount member 51 to the mount attachment portion 44 during vibration of the engine 1, deformation of the exhaust side connecting wall 44E can be suppressed, and vibration of the mount attachment portion 44 can be suppressed.

In addition, according to the cover structure of the engine 1 of this embodiment, the intake side vertical wall portion 41A and the exhaust side vertical wall portion 41B are installed in parallel and connected by the step portion 41C.

The chain cover 40 has a boss 45A near the upper wall 44A, and the boss 45A has an inner end 45a joined to the engine body 2 and an outer end 45b protruding outward from the stepped portion 41C and fastened to the engine body 2 by a bolt 33C. In addition, the exhaust side connecting wall 44E is connected to the boss 45A.

As a result, by connecting the exhaust side connecting wall 44E to the highly rigid boss 45A fastened to the engine body 2, the connection rigidity of the upper wall 44A of the mount attachment portion 44 to the exhaust side vertical wall portion 41B can be further increased.

As a result, when a load F is applied in the vertical direction from the mount member 51 to the mount attachment portion 44 during vibration of the engine 1, deformation of the exhaust side connecting wall 44E can be more effectively suppressed, and vibration of the mount attachment portion 44 can be more effectively suppressed.

In addition, according to the cover structure of the engine 1 of this embodiment, the intake side vertical wall portion 41A has an intake side through hole 41a in which the intake side solenoid 31 that operates the intake side valve timing adjustment device 15 is attached.

In addition, the exhaust side vertical wall portion 41B has an exhaust side through hole 41b in which the exhaust side solenoid 32 that operates the exhaust side valve timing adjustment device 16 is attached, and the exhaust side connecting wall 44E is installed below the exhaust side through hole 41b.

As a result, even if the exhaust side vertical wall portion 41B has an exhaust side through hole 41b and the distance between the upper wall 44A of the mount attachment portion 44 and the lower edge of the exhaust side through hole 41b is short, the highly rigid exhaust side connecting wall 44E can increase the connection rigidity of the upper wall 44A of the mount attachment portion 44 to the exhaust side vertical wall portion 41B.

In addition, according to the cover structure of the engine 1 of this embodiment, the exhaust side connecting wall 44E has an inclined wall 44g that extends obliquely upward from the upper wall 44A of the mount attachment portion 44 toward the exhaust side vertical wall portion 41B, and a top wall 44h that bends horizontally from the rear end portion 44i in the direction in which the inclined wall 44g extends and extends below the exhaust side through hole 41b.

This allows the height of the exhaust side connecting wall 44E to be reduced, and even if the distance from the upper wall 44A of the mount attachment part 44 to the exhaust side through hole 41b is short, a highly rigid exhaust side connecting wall 44E can be installed between the upper wall 44A of the mount attachment part 44 and the exhaust side through hole 41b.

This further increases the connection rigidity of the upper wall 44A of the mount attachment portion 44 to the exhaust side vertical wall portion 41B.

As a result, when a load F is applied in the vertical direction from the mount member 51 to the mount attachment portion 44 during vibration of the engine 1, deformation of the exhaust side connecting wall 44E can be more effectively suppressed, and vibration of the mount attachment portion 44 can be more effectively suppressed.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be encompassed by the following claims.

1...engine (internal combustion engine), 2...engine body (internal combustion engine body), 8...timing chain (transmission member), 9...side member (vehicle body), 11...intake camshaft (first camshaft), 12...exhaust camshaft (second camshaft), 15...intake side valve timing adjustment device (first valve timing adjustment device), 16...exhaust side valve timing adjustment device (second valve timing adjustment device), 33C...bolt (fastener), 31...intake side solenoid (first operating member), 32...exhaust side solenoid (second operating member), 40...chain cover (cover member), 41A...intake side vertical wall portion (first vertical wall portion), 41a...intake side through hole (first through hole), 41B...exhaust side vertical wall portion (second vertical wall portion), 41b...exhaust side through hole (second through hole), 41C...step portion, 41m...lower end (lower end of first vertical wall portion), 41n...lower end (lower end of second vertical wall portion), 44...mount attachment portion, 44A...upper wall, 44b, 44c, 44d...mount boss (fastening portion), 44D...intake side connecting wall (first connecting portion), 44E...exhaust side connecting wall (second connecting portion), 44f...front end (end of first connecting portion on the fastening portion side), 44g...inclined wall, 44h...top wall, 45A...boss (central boss), 45a...inner end (inner end of central boss), 45b...outer end (outer end of central boss), 51...mount member

Claims (4)

a first camshaft and a second camshaft that are rotatably supported on an internal combustion engine body such that their axial directions are parallel to each other, and to which power is transmitted from a crankshaft via a transmission member;
a first valve timing adjusting device attached to an end of the first camshaft and a second valve timing adjusting device attached to an end of the second camshaft;
a cover member attached to an end portion of the internal combustion engine body so as to cover the first valve timing adjustment device, the second valve timing adjustment device, and the transmission member,
the cover member includes a first vertical wall portion covering the first valve timing adjusting device, a second vertical wall portion covering the second valve timing adjusting device and disposed closer to the internal combustion engine body than the first vertical wall portion, and a mount attachment portion located below the first vertical wall portion and the second vertical wall portion and bulging out from the cover member in a direction away from the internal combustion engine body,
A cover structure for an internal combustion engine, the cover structure comprising: a fastening portion for fastening a mount member that supports the internal combustion engine body on a vehicle body, the fastening portion being provided at a tip end portion of an upper wall of the mount attachment portion in a bulging direction,
the cover member has a first connecting portion that connects the upper wall and a lower end of the first vertical wall portion, and a second connecting portion that connects the upper wall and a lower end of the second vertical wall portion,
a second connecting portion that bulges upward in a stepped manner from the upper wall at a position adjacent to the end of the first connecting portion on the fastening portion side in the axial direction of the second camshaft, and is connected to the second vertical wall portion. The first vertical wall portion and the second vertical wall portion are arranged in parallel and connected by a step portion,
The cover member has a central boss adjacent the top wall,
an inner end portion of the central boss is joined to the internal combustion engine body, and an outer end portion of the central boss protrudes outward from the stepped portion and is fastened to the internal combustion engine body by a fastener;
2. The cover structure for an internal combustion engine according to claim 1, wherein the second connecting portion is connected to the central boss. the first vertical wall portion has a first through hole to which a first operating member that operates the first valve timing adjusting device is attached,
the second vertical wall portion has a second through hole to which a second operating member that operates the second valve timing adjusting device is attached,
3. The cover structure for an internal combustion engine according to claim 1, wherein the second connecting portion is disposed below the second through hole. The cover structure for an internal combustion engine according to claim 3, characterized in that the second connecting portion has an inclined wall that extends obliquely upward from the upper wall of the mount attachment portion toward the second vertical wall portion, and a top wall that bends horizontally from the end of the inclined wall in the extending direction and extends below the second through hole.

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