JP7528766B2 - Internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine.

Conventionally, engines equipped with variable valve timing mechanisms are known as engines mounted on vehicles (see Patent Document 1).

In this engine with variable valve timing mechanism, an intake actuator and an exhaust actuator are attached to one axial end of the intake camshaft and the exhaust camshaft.

The intake side actuator and exhaust side actuator are operated by hydraulic oil supplied from the hydraulic control valve, changing the rotational phase of the intake camshaft and exhaust camshaft relative to the crankshaft.

The intake side actuator and the exhaust side actuator are covered by a cover member. A mount attachment portion is provided on the upper part of the cover member, and the mount attachment portion is connected to the vehicle body via the engine mount.

JP 2008-215323 A

However, in conventional engines with variable valve timing mechanisms, one end face of the intake actuator facing the cover member and one end face of the exhaust actuator are located on the same plane.

In addition, the wall surface of the cover member that faces one end face of the intake actuator and one end face of the exhaust actuator is flat, and a mount attachment portion is provided on the flat surface.

As a result, the surface rigidity of the cover member at the location where the mount attachment part is installed decreases, making the mount attachment part more susceptible to vibration due to engine vibration, which may reduce the support rigidity of the internal combustion engine. Therefore, there is still room for improvement in order to increase the support rigidity of the internal combustion engine.

The present invention was made in response to the above-mentioned problems, and aims to provide an internal combustion engine that can improve the surface rigidity of the cover member at the location where the mount attachment part is installed, suppress vibration of the mount attachment part due to vibration of the internal combustion engine, and increase the support rigidity of the internal combustion engine.

The present invention relates to an intake camshaft and an exhaust camshaft that are rotatably mounted on an internal combustion engine body with their axes parallel to each other and to which power from a crankshaft is transmitted via a transmission member; an intake variable valve operating device that is provided at one end of the intake camshaft in the axial direction and changes the relative rotational phase of the intake camshaft with respect to the crankshaft; an exhaust variable valve operating device that is provided at one end of the exhaust camshaft in the axial direction and changes the relative rotational phase of the exhaust camshaft with respect to the crankshaft; a cover member that is attached to one end of the internal combustion engine body and that houses the transmission member; and an intake solenoid provided coaxially with the axis of the intake camshaft and operating the intake variable valve operating device, and an exhaust solenoid provided coaxially with the axis of the exhaust camshaft and operating the exhaust variable valve operating device, the cover member having an intake side wall portion facing the intake variable valve operating device in the axial direction of the intake camshaft and an exhaust side wall portion facing the exhaust variable valve operating device in the axial direction of the exhaust camshaft, The valve train is installed such that one of the end face of the intake variable valve train and the end face of the exhaust variable valve train that faces the cover member is located closer to the internal combustion engine body in the axial direction of the intake camshaft and the exhaust camshaft than the other of the end faces of the intake variable valve train and the exhaust variable valve train, and the cover member is such that one of the intake side wall portion and the exhaust side wall portion is recessed closer to the internal combustion engine body than the other of the intake side wall portion and the exhaust side wall portion, and the mount attachment portion is disposed between at least the intake side wall portion and The intake side wall portion is provided at a step portion connecting the intake side wall portion, and the intake side wall portion has an intake side opening into which the intake solenoid is inserted, and an intake side annular portion which protrudes outward from the cover member so as to surround the intake side opening and to which the intake solenoid is fixed, and the exhaust side wall portion has an exhaust side opening into which the exhaust solenoid is inserted, and an exhaust side annular portion which protrudes outward from the cover member so as to surround the exhaust side opening and to which the exhaust solenoid is fixed, and the intake side annular portion and the exhaust side annular portion are connected to the step portion .

In this way, the present invention improves the surface rigidity of the cover member at the installation location of the mount attachment part, suppresses vibration of the mount attachment part due to vibration of the internal combustion engine, and increases the support rigidity of the internal combustion engine.

FIG. 1 is a right side view of an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a right side view of an internal combustion engine according to an embodiment of the present invention, showing the upper right side view of the internal combustion engine with the intake solenoid and exhaust solenoid removed. FIG. 3 is a top view of an internal combustion engine according to one embodiment of the present invention, specifically, a top view of the right side portion of the internal combustion engine with the cylinder head cover removed. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5(a) is a configuration diagram of an intake variable valve operating system for an internal combustion engine according to one embodiment of the present invention, and FIG. 5(b) is a configuration diagram of an exhaust variable valve operating system for an internal combustion engine according to one embodiment of the present invention.

An internal combustion engine according to one embodiment of the present invention is an internal combustion engine including an intake camshaft and an exhaust camshaft that are rotatably mounted on the internal combustion engine body with their axes parallel to each other and to which the power of the crankshaft is transmitted via a transmission member, an intake variable valve mechanism that is provided at one end of the axial direction of the intake camshaft and changes the relative rotation phase of the intake camshaft with respect to the crankshaft, an exhaust variable valve mechanism that is provided at one end of the axial direction of the exhaust camshaft and changes the relative rotation phase of the exhaust camshaft with respect to the crankshaft, a cover member that is attached to one end of the internal combustion engine body and that houses the transmission member, and a mount attachment portion that is provided on the cover member and to which a mount member that supports the internal combustion engine body on a vehicle body is attached, the cover member being axially aligned with the axial direction of the intake camshaft. The intake variable valve device and the exhaust variable valve device have an intake side wall portion facing the intake variable valve device in the axial direction and an exhaust side wall portion facing the exhaust variable valve device in the axial direction of the exhaust camshaft, and the intake variable valve device and the exhaust variable valve device are installed so that one of the end faces of the intake variable valve device and the exhaust variable valve device facing the cover member is located closer to the internal combustion engine body in the axial direction of the intake camshaft and the exhaust camshaft than the other of the end faces of the intake variable valve device and the exhaust variable valve device, and the cover member has one of the intake side wall portion and the exhaust side wall portion recessed closer to the internal combustion engine body than the other of the intake side wall portion and the exhaust side wall portion, and the mount attachment portion is provided on a step portion connecting at least the intake side wall portion and the exhaust side wall portion.

As a result, the internal combustion engine according to one embodiment of the present invention can improve the surface rigidity of the cover member at the location where the mount attachment part is installed, suppress vibration of the mount attachment part due to vibration of the internal combustion engine, and increase the support rigidity of the internal combustion engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an internal combustion engine according to the present invention will now be described with reference to the drawings.
1 to 5 are diagrams showing an internal combustion engine according to an embodiment of the present invention. In Fig. 1 to 5, the up, down, front, rear, left and right directions are based on the internal combustion engine installed in a vehicle, the front and rear direction of the vehicle is the front-rear direction, the left and right direction of the vehicle (vehicle width direction) is the left and right direction, and the up and down direction of the vehicle (vehicle height direction) is the up and down direction.

First, the configuration will be described.
In Fig. 1, an engine 1 mounted on a vehicle includes an engine body 2. As shown in Fig. 4, the engine body 2 includes a cylinder block 3 and a cylinder head 4. The cylinder head 4 is attached to an upper portion of the cylinder block 3.

A cylinder head cover 5 is attached to the top of the cylinder head 4, and an oil pan 6 for storing oil is attached to the bottom of the cylinder block 3 (see Figure 1). In this embodiment, the engine 1 constitutes an internal combustion engine, and the engine body 2 constitutes the internal combustion engine body.

The cylinder block 3 has multiple cylinders (not shown), which are aligned in the width direction of the vehicle (hereinafter referred to as the vehicle width direction), which is the left-right direction.

Each cylinder contains a piston (not shown), which is connected to the crankshaft 3S (see FIG. 1) via a connecting rod (not shown). The piston reciprocates within the cylinder, causing the crankshaft to rotate via the connecting rod. The cylinder head 4 is formed with 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. 3, an intake camshaft 11 and an exhaust camshaft 12 are installed in the cylinder head 4. The intake camshaft 11 and the exhaust camshaft 12 are rotatably supported in the cylinder head 4 by bearing caps 13.

The intake camshaft 11 and exhaust camshaft 12 are installed side by side in the fore-and-aft direction so that their axes 11a and 12a extend parallel to the vehicle width direction.

The intake camshaft 11 has multiple intake cams 11A (one shown), and the intake cams 11A are arranged in a line along the axis 11a of the intake camshaft 11. Hereinafter, the direction of the axis 11a of the intake camshaft 11 is referred to as the axial direction.

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 (one shown), and the exhaust cams 12A are arranged in a line along the axis 12a of the exhaust camshaft 12. Hereinafter, the direction of the axis 12a of the exhaust camshaft 12 is referred to as the axial direction.

The axial directions of the intake camshaft 11 and exhaust camshaft 12 are parallel, and for ease of explanation, the axial direction of the intake camshaft 11 and exhaust camshaft 12 is sometimes referred to as the axial direction of the intake camshaft 11.

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 variable valve mechanism 15 is attached to the right end (one end) of the intake camshaft 11 in the axial direction. The intake variable valve mechanism 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 variable valve mechanism 16 is attached to the right end (one end) of the exhaust camshaft 12 in the axial direction. The exhaust variable valve mechanism 16 has an exhaust side housing member 25, and an exhaust sprocket 25S is provided on the outer periphery of the exhaust side housing member 25.

As shown in FIG. 1, a crank sprocket 3A is provided on the right end of the crankshaft 3S. A timing chain 19 is wound around the crank sprocket 3A, the intake sprocket 23S, and the exhaust sprocket 25S. In this embodiment, the timing chain 19 constitutes a transmission member.

The power of the crankshaft 3S is transmitted to the intake camshaft 11 and the exhaust camshaft 12 via a timing chain 19. This causes the intake cam 11A to rotate and opens and closes the intake valve, and the exhaust cam 12A to rotate and opens and closes the exhaust valve.

The intake variable valve mechanism 15 changes the relative rotational phase of the intake camshaft 11 with respect to the crankshaft 3S, and the exhaust variable valve mechanism 16 changes the relative rotational phase of the exhaust camshaft 12 with respect to the crankshaft 3S.

A chain cover 20 is attached to the right end of the cylinder block 3 and the right end of the cylinder head 4. Specifically, a flange portion 20F is formed on the outer periphery of the chain cover 20, and the flange portion 20F of the chain cover 20 is fastened to the right end of the cylinder block 3 and the right end of the cylinder head 4 by a plurality of bolts 33A.

The chain cover 20 houses the timing chain 19 (see FIG. 1). That is, the timing chain 19 is installed in a space 30 (see FIG. 4) surrounded by the cylinder block 3, the cylinder head 4, and the chain cover 20. In this embodiment, the chain cover 20 constitutes a cover member.

As shown in Figures 3 and 4, a mount attachment portion 21 is provided on the upper part of the right side surface 20r of the chain cover 20. The mount attachment portion 21 bulges out to the right from the right side surface 20r of the chain cover 20.

As shown in FIG. 4, a right side member 7 is provided to the right of the engine 1 and extends in the front-to-rear direction of the vehicle. A mount member 22 is provided on the mount attachment portion 21.

The mount member 22 has a mount bracket 22A, and the left end of the mount bracket 22A is fixed to the mount attachment part 21 by a bolt (not shown).

The mount member 22 includes a vibration absorbing member 22B, which is attached to the right side member 7. The right end of the mount bracket 22A is attached to the vibration absorbing member 22B, and the mount attachment portion 21 is elastically supported by the right side member 7 via the mount member 22.

As a result, vibrations of the engine 1 can be absorbed by the mount member 22, and vibrations transmitted from the engine 1 to the right side member 7 can be reduced. The transmission is elastically supported on the left side member (not shown) by a mount member (not shown). In this embodiment, the right side member 7 constitutes the vehicle body.

As shown in FIG. 4, the chain cover 20 has a bulge 20E. The bulge 20E bulges leftward from the right side surface 20r of the chain cover 20 above the mount attachment portion 21, and covers the front of the intake variable valve mechanism 15 and the rear of the exhaust variable valve mechanism 16.

As shown in FIG. 3, the dimensions of the exhaust variable valve mechanism 16 in the axial direction of the exhaust camshaft 12 are shorter than the dimensions of the intake variable valve mechanism 15 in the axial direction of the intake camshaft 11.

As shown in FIG. 5(a), the intake variable valve mechanism 15 has an intake side housing member 23, and the power of the crankshaft 3S is transmitted to the intake side housing member 23 via a timing chain 19.

The intake side housing member 23 houses the intake side vane rotor 24, which has a rotor 24A and three vanes 24B. In this embodiment, the intake side housing member 23 constitutes a housing member, and the intake side vane rotor 24 constitutes a vane rotor.

The rotor 24A is connected to the right end of the intake camshaft 11 and rotates integrally with the intake camshaft 11. The vanes 24B protrude radially outward from the rotor 24A and divide the interior of the intake side housing member 23 into multiple advance chambers 23A and multiple retard chambers 23B.

The rotor 24A has multiple advance side oil passages 24a and retard side oil passages 24b formed in it.

The engine 1 is provided with an oil pump (not shown), and the oil supplied from the oil pump is switched by an intake solenoid 31 (described later) so that the oil is supplied to either the advance oil passage 24a or the retard oil passage 24b.

When the intake solenoid 31 switches the supply path to the advance oil passage 24a, oil is supplied from the advance oil passage 24a to the advance chamber 23A.

When oil is introduced into the advance chamber 23A, the intake vane rotor 24 rotates relative to the intake housing member 23, changing the relative rotation phase of the intake camshaft 11 to the crankshaft 3S to the advance side, and changing the opening and closing timing of the exhaust valve to the advance side.

When the intake solenoid 31 switches the supply path to the retarded oil passage 24b, oil is supplied from the retarded oil passage 24b to the retarded chamber 23B.

When oil is introduced into the retard chamber 23B, the relative rotational phase of the intake camshaft 11 with respect to the crankshaft 3S is shifted to the retard side, and the opening and closing timing of the exhaust valve is shifted to the retard side.

As shown in FIG. 5(b), the exhaust variable valve mechanism 16 has an exhaust side housing member 25, and the power of the crankshaft 3S is transmitted to the exhaust side housing member 25 via a timing chain 19.

As shown in FIG. 3, the dimension of the exhaust side housing member 25 in the axial direction of the exhaust camshaft 12 is shorter than the dimension of the intake side housing member 23 in the axial direction of the intake camshaft 11.

Specifically, the length of the exhaust side housing member 25 in the axial direction of the exhaust camshaft 12 is approximately half the length of the intake side housing member 23 in the axial direction of the intake camshaft 11.

As shown in FIG. 5(b), the exhaust side housing member 25 houses the exhaust side vane rotor 26, which has a rotor 26A and four vanes 26B. In this embodiment, the exhaust side housing member 25 constitutes a housing member, and the exhaust side vane rotor 26 constitutes a vane rotor.

The rotor 26A is connected to the right end of the exhaust camshaft 12 and rotates integrally with the exhaust camshaft 12. The vanes 26B protrude radially outward from the rotor 26A and divide the interior of the exhaust side housing member 25 into multiple advance chambers 25A and multiple retard chambers 25B.

The rotor 26A has multiple advance side oil passages 26a and retard side oil passages 26b formed.

The oil supplied from the oil pump is switched by an exhaust solenoid 32 (described later) so that the oil is supplied to either the advance oil passage 26a or the retard oil passage 26b.

When the exhaust solenoid 32 switches the supply path to the advance oil passage 26a, oil is supplied from the advance oil passage 26a to the advance chamber 25A.

When oil is introduced into the advance chamber 25A, the exhaust vane rotor 26 rotates relative to the exhaust housing member 25, changing the relative rotation phase of the exhaust camshaft 12 to the crankshaft 3S to the advance side, and changing the opening and closing timing of the exhaust valve to the advance side.

When the exhaust solenoid 32 switches the supply path to the retard side oil passage 26b, oil is supplied from the retard side oil passage 26b to the retard chamber 25B.

When oil is introduced into the retard chamber 25B, the relative rotational phase of the exhaust camshaft 12 with respect to the crankshaft 3S is shifted to the retard side, and the opening and closing timing of the exhaust valve is shifted to the retard side.

The operating angle α1 of the vane 24B of the exhaust variable valve mechanism 16 is configured to be smaller than the operating angle α2 of the vane 26B of the intake variable valve mechanism 15. In other words, the operating range of the relative rotation angle of the intake side vane rotor 24 with respect to the intake side housing member 23 is larger than the operating range of the relative rotation angle of the exhaust side vane rotor 26 with respect to the exhaust side housing member 25.

As shown in FIG. 3, the intake variable valve train 15 and the exhaust variable valve train 16 are installed so that the right end face of the exhaust variable valve train 16 is located closer to the engine body 2 in the axial direction of the intake camshaft 11 than the right end face of the intake variable valve train 15.

Specifically, the intake variable valve mechanism 15 and the exhaust variable valve mechanism 16 are installed so that the right end surface 25r of the exhaust side housing member 25 is located closer to the engine body 2 in the axial direction of the intake camshaft 11 than the right end surface 23r of the intake side housing member 23.

In this embodiment, the right end surface 23r of the intake side housing member 23 constitutes the end surface of the intake variable valve mechanism, and the right end surface 25r of the exhaust side housing member 25 constitutes the end surface of the exhaust variable valve mechanism.

As shown in FIG. 3, the chain cover 20 has an intake side wall portion 20A that faces the intake variable valve mechanism 15 in the axial direction of the intake camshaft 11, and an exhaust side wall portion 20B that faces the exhaust variable valve mechanism 16 in the axial direction of the exhaust camshaft 12.

The exhaust side wall portion 20B is recessed toward the engine body 2 relative to the intake side wall portion 20A. In other words, the exhaust side wall portion 20B is recessed toward the engine body 2 relative to the intake side wall portion 20A, and the intake side wall portion 20A bulges away from the engine body 2 relative to the exhaust side wall portion 20B.

The intake side wall portion 20A and the exhaust side wall portion 20B are connected by a step portion 20C in a direction perpendicular to the axial direction of the intake camshaft 11 (front-rear direction). In FIG. 2, the range of the step portion 20C in the front-rear direction is indicated by the arrow 20C.

As shown in FIG. 2, the mount attachment portion 21 is provided on the intake side wall portion 20A, the exhaust side wall portion 20B, and the step portion 20C. Specifically, the mount attachment portion 21 bulges out to the right from the intake side wall portion 20A, the exhaust side wall portion 20B, and the step portion 20C.

As shown in Figures 1 and 3, the chain cover 20 is provided with an intake solenoid 31 and an exhaust solenoid 32.

As shown in FIG. 2, the intake side wall portion 20A has an intake side opening 20a into which the intake solenoid 31 is inserted, and an intake side annular portion 20b that surrounds the intake side opening 20a, protrudes to the right (outward) from the chain cover 20, and to which the intake solenoid 31 is fixed by bolts (not shown).

The exhaust side wall portion 20B has an exhaust side opening 20c into which the exhaust solenoid 32 is inserted, and an exhaust side annular portion 20d that surrounds the exhaust side opening 20c, protrudes to the right (outward) from the chain cover 20, and to which the exhaust solenoid 32 is fixed by bolts 33B (see Figure 1).

As shown in FIG. 2, the front end of the intake side annular portion 20b and the rear end of the exhaust side annular portion 20d are connected to the stepped portion 20C.

The intake solenoid 31 is arranged coaxially with the axis 11a of the intake camshaft 11 and operates the intake variable valve mechanism 15.

Specifically, the intake solenoid 31 has a plunger portion (not shown), and the plunger portion is connected to the intake variable valve mechanism 15 through the intake side opening 20a.

The intake solenoid 31 switches the supply path through which oil is supplied from the oil pump to either the advance oil passage 24a or the retard oil passage 24b by moving the plunger portion in the vehicle width direction (left and right direction).

The intake solenoid 31 being arranged coaxially with the axis 11a of the intake camshaft 11 means that the intake solenoid 31 is located on the axis 11a of the intake camshaft 11.

The exhaust solenoid 32 is provided coaxially with the axis 12a of the exhaust camshaft 12 and operates the exhaust variable valve mechanism 16. Specifically, the exhaust solenoid 32 has a plunger portion (not shown), which is connected to the exhaust variable valve mechanism 16 through the exhaust side opening 20c.

The exhaust solenoid 32 switches the supply path through which oil is supplied from the oil pump to either the advance oil passage 26a or the retard oil passage 26b by moving the plunger portion in the vehicle width direction.

The exhaust solenoid 32 being arranged coaxially with the axis 12a of the exhaust camshaft 12 means that the exhaust solenoid 32 is located on the axis 12a of the exhaust camshaft 12.

As shown in Figures 1 and 2, a boss portion 20D is provided on the step portion 20C of the chain cover 20.

As shown in FIG. 4, the boss portion 20D is provided on the bulge portion 20E, and the rear end of the bulge portion 20E abuts against the cylinder head 4. The cylinder head 4 is provided with a bolt fastening groove 4A, and the bolt fastening groove 4A faces the boss portion 20D in the vehicle width direction.

The chain cover 20 has a step portion 20C fastened to the cylinder head 4 by inserting a bolt 33C through the boss portion 20D and fastening the bolt 33C to the bolt fastening groove 4A of the cylinder head 4. The boss portion 20D and the bolt 33C of this embodiment constitute the fastening portion of the present invention.

Next, the effects of the engine 1 according to this embodiment will be described.
The engine 1 of this embodiment has an intake camshaft 11 and an exhaust camshaft 12 that are rotatably mounted on the engine body 2 with their axes 11a, 12a parallel to each other, and to which the power of the crankshaft 3S is transmitted via a timing chain 19.

The engine 1 also has an intake variable valve mechanism 15 that is provided at the right end (one end) in the axial direction of the intake camshaft 11 and changes the relative rotational phase of the intake camshaft 11 with respect to the crankshaft 3S, and an exhaust variable valve mechanism 16 that is provided at the right end (one end) in the axial direction of the exhaust camshaft 12 and changes the relative rotational phase of the exhaust camshaft 12 with respect to the crankshaft 3S.

The engine 1 also has a chain cover 20 that is attached to the right end (one end) of the cylinder block 3 and the cylinder head 4 and that houses the timing chain 19, and a mount attachment portion 21 that is provided on the chain cover 20 and to which a mount member 22 that supports the engine body 2 on the right side member 7 is attached.

The chain cover 20 has an intake side wall portion 20A that faces the intake variable valve mechanism 15 in the axial direction of the intake camshaft 11, and an exhaust side wall portion 20B that faces the exhaust variable valve mechanism 16 in the axial direction of the exhaust camshaft 12.

The intake variable valve train 15 and the exhaust variable valve train 16 are installed so that the right end face of the exhaust variable valve train 16 (right end face 25r of the exhaust side housing member 25) that faces the chain cover 20 is located closer to the engine body 2 in the axial direction of the intake camshaft 11 than the right end face of the intake variable valve train 15 (right end face 23r of the intake side housing member 23).

In addition, the exhaust side wall portion 20B of the chain cover 20 is recessed toward the engine body 2 relative to the intake side wall portion 20A, and the mount attachment portion 21 is provided on the intake side wall portion 20A, the exhaust side wall portion 20B, and the step portion 20C that connects the intake side wall portion 20A and the exhaust side wall portion 20B.

In this way, by providing the step portion 20C on the chain cover 20, the surface rigidity of the chain cover 20 at the installation location of the mount attachment portion 21 can be increased, and vibration of the mount attachment portion 21 due to vibration of the engine 1 can be suppressed. As a result, the support rigidity of the engine 1 can be increased.

In addition, with the engine 1 of this embodiment, the exhaust variable valve mechanism 16 is shorter in the axial direction of the intake camshaft 11 than the intake variable valve mechanism 15.

This allows the axial length of the exhaust camshaft 12 to be shorter than the axial length of the intake camshaft 11, thereby reducing the installation space required for the exhaust camshaft 12 relative to the cylinder head 4.

In the engine 1, the intake variable valve train 15 and the exhaust variable valve train 16 may be installed so that the right end face of the intake variable valve train 15 facing the chain cover 20 (right end face 23r of the intake side housing member 23) is located closer to the engine body 2 in the axial direction of the intake camshaft 11 than the right end face of the exhaust variable valve train 16 (right end face 25r of the exhaust side housing member 25).

The chain cover 20 may also have the intake side wall portion 20A recessed toward the engine body 2 relative to the exhaust side wall portion 20B.

Furthermore, the intake variable valve mechanism 15 may be configured so that the axial dimension of the intake camshaft 11 is shorter than that of the exhaust variable valve mechanism 16.

Furthermore, according to the engine 1 of this embodiment, the intake variable valve mechanism 15 is equipped with an intake side vane rotor 24 housed in the intake side housing member 23.

The intake side vane rotor 24 has a rotor 24A that is connected to the intake camshaft 11 and multiple vanes 24B that protrude radially outward from the rotor 24A and divide the interior of the intake side housing member 23 into multiple advance chambers 23A and multiple retard chambers 23B, and rotates relative to the intake side housing member 23 by the hydraulic pressure introduced into the advance chamber 23A or retard chamber 23B.

The exhaust variable valve mechanism 16 also includes an exhaust vane rotor 26 housed in an exhaust housing member 25.

The exhaust-side vane rotor 26 has a rotor 26A that is connected to the exhaust camshaft 12 and multiple vanes 26B that protrude radially outward from the rotor 26A and divide the interior of the exhaust-side housing member 25 into multiple advance chambers 25A and multiple retard chambers 25B, and rotates relative to the exhaust-side housing member 25 by the hydraulic pressure introduced into the advance chambers 25A or retard chambers 25B.

The number of vanes 26B provided on the exhaust variable valve mechanism 16 is greater than the number of vanes 24B provided on the intake variable valve mechanism 15.

As a result, when the axial length of the exhaust variable valve mechanism 16 is shortened, the area of the vanes 26B is reduced, but the number of vanes 26B is increased, thereby maintaining the responsiveness of the exhaust valve opening and closing timing.

Specifically, the theoretical drive torque of the variable valve gear is calculated by the following formula (1). Here, the theoretical drive torque is the torque that the vane can withstand when it receives torque from the intake and exhaust valves.

Theoretical driving torque (Nmm) = hydraulic pressure acting on the vane x number of vanes x pressure area of the vane... (1)

According to the above formula (1), when the same drive torque is ensured for the intake variable valve train 15 and the exhaust variable valve train 16, the pressurized area of the vanes 26B can be reduced by the amount of increase in the number of vanes 26B of the exhaust variable valve train 16, so that the responsiveness of the exhaust valve opening and closing timing can be maintained even if the axial dimension of the exhaust variable valve train 16 is shortened.

The number of vanes 24B, 26B of the intake variable valve train 15 and exhaust variable valve train 16 are not limited to three and four, respectively.

In addition, according to the engine 1 of this embodiment, the intake variable valve train 15 and the exhaust variable valve train 16 are installed so that the right end face of the exhaust variable valve train 16 facing the chain cover 20 is located closer to the engine body 2 in the axial direction of the intake camshaft 11 than the right end face of the intake variable valve train 15.

In addition, the exhaust side wall portion 20B of the chain cover 20 is recessed toward the engine body 2 relative to the intake side wall portion 20A.

As a result, if the number of vanes 26B of the exhaust variable valve train 16 is set to four in order to shorten the axial length of the exhaust variable valve train 16, the operating angle α1 of the vane 26B becomes smaller than the operating angle α2 of the vane 24B of the intake variable valve train 15 (see Figure 5).

However, even if the operating angle α1 of the vane 26B of the exhaust variable valve train 16 is made smaller than the operating angle α2 of the vane 24B of the intake variable valve train 15, the exhaust variable valve train 16 provided on the exhaust side has less of an effect on the operability of the engine 1 compared to the intake variable valve train 15, so the axial length of the exhaust variable valve train 16 can be reliably shortened.

In addition, since the axial length of the exhaust variable valve train 16 can be made shorter than the axial length of the intake variable valve train 15, the axial lengths of the intake camshaft 11 and the exhaust camshaft 12 may be made the same. In this case, the axial length of the exhaust camshaft 12 including the exhaust variable valve train 16 can be made shorter than the axial length of the intake camshaft 11 including the intake variable valve train 15.

The engine 1 of this embodiment also has an intake solenoid 31 that is arranged coaxially with the axis 11a of the intake camshaft 11 and operates the intake variable valve mechanism 15, and an exhaust solenoid 32 that is arranged coaxially with the axis 12a of the exhaust camshaft 12 and operates the exhaust variable valve mechanism 16.

The intake side wall portion 20A has an intake side opening 20a into which the intake solenoid 31 is inserted, and an intake side annular portion 20b that protrudes to the right from the chain cover 20 so as to surround the intake side opening 20a and to which the intake solenoid 31 is fixed.

The exhaust side wall portion 20B has an exhaust side opening 20c into which the exhaust solenoid 32 is inserted, and an exhaust side annular portion 20d that protrudes to the right from the chain cover 20 so as to surround the exhaust side opening 20c and to which the exhaust solenoid 32 is fixed.

In addition, the intake side annular portion 20b and the exhaust side annular portion 20d are connected to the stepped portion 20C.

As a result, the rigidity of the step portion 20C can be further increased by the intake side annular portion 20b and the exhaust side annular portion 20d, and the surface rigidity of the chain cover 20 at the installation location of the mount attachment portion 21 can be more effectively increased.

This makes it possible to more effectively prevent the mount attachment portion 21 from vibrating due to engine 1 vibration, and further increase the support rigidity of the engine 1.

In addition, according to the engine 1 of this embodiment, the chain cover 20 has a boss portion 20D and a bolt 33C that fasten the chain cover 20 to the cylinder head 4, and the boss portion 20D and the bolt 33C are provided on the step portion 20C.

As a result, the rigidity of the stepped portion 20C can be further increased by fastening the stepped portion 20C to the cylinder head 4 with the bolt 33C.

This makes it possible to more effectively increase the surface rigidity of the chain cover 20 at the location where the mount attachment portion 21 is installed, and more effectively suppress vibration of the mount attachment portion 21 due to vibration of the engine 1. As a result, the support rigidity of the engine 1 can be further increased.

In addition, the mount attachment portion 21 in this embodiment may be provided on the intake side wall portion 20A and the step portion 20C, on the exhaust side wall portion 20B and the step portion 20C, or only on the step portion 20C.

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 included in the following claims.

1...engine (internal combustion engine), 2...engine body (internal combustion engine body), 3S...crankshaft, 7...right side member (vehicle body), 11...intake camshaft, 11a...axis (axis of intake camshaft), 12...exhaust camshaft, 12a...axis (axis of exhaust camshaft), 15...intake variable valve train, 16...exhaust variable valve train, 19...timing chain (transmission member), 20...chain cover (cover member), 20A...intake side wall portion, 20a...intake side opening, 20B...exhaust side wall portion, 20b...intake side annular portion, 20C...step portion, 20c...exhaust side opening, 20D...boss portion (fastening portion), 20d... Exhaust side annular portion, 21...mount attachment portion, 22...mount member, 23...intake side housing member (housing member), 23A, 25A...advance chamber, 23B, 25B...retard chamber, 23r...right end face (end face of intake variable valve train), 24...intake side vane rotor (vane rotor), 24A...rotor, 24B...vane, 25...exhaust side housing member (housing member), 25r...right end face (end face of exhaust variable valve train), 26...exhaust side vane rotor (vane rotor), 26A...rotor, 26B...vane, 31...intake solenoid, 32...exhaust solenoid, 33C...bolt (fastening portion)

Claims (5)

an intake camshaft and an exhaust camshaft that are rotatably mounted on the internal combustion engine body with their axes parallel to each other and to which the power of the crankshaft is transmitted via a transmission member;
an intake variable valve device provided at one axial end of the intake camshaft to change a relative rotation phase of the intake camshaft with respect to the crankshaft;
an exhaust variable valve mechanism provided at one end of the exhaust camshaft in an axial direction thereof for varying a relative rotation phase of the exhaust camshaft with respect to the crankshaft;
a cover member attached to one end of the internal combustion engine body and housing the conductive member;
a mount attachment portion provided on the cover member to which a mount member for supporting the internal combustion engine body on a vehicle body is attached,
an intake solenoid provided coaxially with the axis of the intake camshaft and actuating the intake variable valve operating device, and an exhaust solenoid provided coaxially with the axis of the exhaust camshaft and actuating the exhaust variable valve operating device,
the cover member has an intake side wall portion facing the intake variable valve operating device in the axial direction of the intake camshaft, and an exhaust side wall portion facing the exhaust variable valve operating device in the axial direction of the exhaust camshaft,
the intake variable valve operating device and the exhaust variable valve operating device are installed such that one of an end face of the intake variable valve operating device and an end face of the exhaust variable valve operating device that faces the cover member is positioned closer to the internal combustion engine body in the axial direction of the intake camshaft and the exhaust camshaft than the other of the end faces of the intake variable valve operating device and the exhaust variable valve operating device,
the cover member is configured such that one of the intake side wall portion and the exhaust side wall portion is recessed toward the internal combustion engine body relative to the other of the intake side wall portion and the exhaust side wall portion,
the mount attachment portion is provided at a step portion that connects at least the intake side wall portion and the exhaust side wall portion,
the intake side wall portion has an intake side opening into which the intake solenoid is inserted, and an intake side annular portion that surrounds the intake side opening, protrudes outward from the cover member, and to which the intake solenoid is fixed,
the exhaust side wall portion has an exhaust side opening into which the exhaust solenoid is inserted, and an exhaust side annular portion that surrounds the exhaust side opening, protrudes outward from the cover member, and to which the exhaust solenoid is fixed,
The internal combustion engine , wherein the intake side annular portion and the exhaust side annular portion are connected to the step portion . 2. The internal combustion engine according to claim 1, wherein one of the intake variable valve operating system and the exhaust variable valve operating system has a shorter axial dimension of the intake camshaft and the exhaust camshaft than the other of the intake variable valve operating system and the exhaust variable valve operating system. Each of the intake variable valve operating device and the exhaust variable valve operating device is
a housing member to which the power of the crankshaft is transmitted via the transmission member, and a vane rotor;
The vane rotor is
the rotor is accommodated in the housing member and is connected to the intake camshaft and the exhaust camshaft, respectively, and a plurality of vanes protrude radially outward from the rotor and divide the interior of the housing member into a plurality of advance chambers and a plurality of retard chambers, and the rotor is configured to rotate relative to the housing member by hydraulic oil pressure introduced into the advance chambers or the retard chambers,
3. The internal combustion engine according to claim 1, wherein the number of vanes provided in either the intake variable valve operating system or the exhaust variable valve operating system is greater than the number of vanes provided in the other of the intake variable valve operating system or the exhaust variable valve operating system. the exhaust variable valve operating device is installed such that an end face of the exhaust variable valve operating device is located closer to the internal combustion engine body in an axial direction of the intake camshaft and the exhaust camshaft than an end face of the intake variable valve operating device,
4. The internal combustion engine according to claim 1, wherein the exhaust side wall of the cover member is recessed toward the internal combustion engine body with respect to the intake side wall. The cover member has a fastening portion that fastens the cover member to the internal combustion engine body,
5. The internal combustion engine according to claim 1 , wherein the fastening portion is provided at the step portion .

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