JPH10196322A - Cam control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device to be comparatively small and simple in structure as a device to control the rotation phase of the cam of the cam shaft of an engine. SOLUTION: A cam gear 9 to which a rotation force is transmitted from the crank shaft of an engine is fitted in a camshaft 2 through a first helical spline 5. An intake and exhaust cam body 12 is fitted in the cam shaft 2 through a second helical spline 6 in the same direction as that of the first helical spline 5 and a unit injector cam body 19 is fitted in the camshaft 2 through a third helical spline 7 in a reverse direction to the first helical spline 5. A piston 8 fixed on the camshaft 2 is fitted in a hydraulic cylinder 10 formed integrally with the internal part of the cam gear 9. The camshaft 2 is axially displaceable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling a rotation phase of a cam on a camshaft of an engine.

[0002]

2. Description of the Related Art Conventionally, in order to control the rotation phase of a cam on a camshaft of an engine, Japanese Patent Laid-Open Publication No.
As exemplified in Japanese Unexamined Patent Application Publication No. 1 (1993), a cam pulley and a cam shaft of an engine are connected by engagement of a helical spline shaft and a helical spline hole, and a piston member integrated with the cam shaft and disposed in a cylinder member. By applying hydraulic pressure to displace the camshaft in its axial direction, the camshaft is rotationally displaced relative to the cam pulley.

However, in this case, since the hydraulic cylinder is installed separately from the cam pulley and the like, the overall structure of the valve tamping control device including the camshaft moving means becomes large, and the housing of each part is increased. This is a problem for diesel engines for vehicles where space is particularly tight. In addition, the piston member always rotates with respect to the stationary cylinder member as the camshaft rotates. At the same time, there is a need to specially install a thrust metal or the like between the thrust regulating member integrally formed on the piston member and the inner surface of the cylinder member to cope with the rotational thrust load. There was a disadvantage that the structure became complicated.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device for controlling the rotation phase of a cam on a camshaft of an engine, which is relatively small and has a simple structure.

[0005]

According to the present invention, there is provided a cam control device for an engine according to the present invention, wherein a driving member that fits with an outer peripheral surface of a camshaft by a helical spline portion and transmits a rotational force to the camshaft; An actuator for displacing the camshaft in the axial direction, wherein the actuator is connected to the camshaft and a cylinder member formed by at least a part of the driving member and rotating integrally with the driving member. A piston member fitted in the cylinder member, and biasing means for displacing the piston member in the axial direction of the camshaft.

That is, since the camshaft and the driving member for transmitting the rotational force to the camshaft are fitted by the helical spline portion, the camshaft is displaced in the axial direction by the actuator to rotate the camshaft. While the phase can be changed, at least a part of the driving member forms a cylinder member of the actuator, and the cylinder member is configured to rotate integrally with the driving member. And a piston member connected to the camshaft and fitted in the cylinder member, and the cam control device can be easily miniaturized. Except for the temporary case of controlling the cam rotation phase Since pairs rotation does not occur, the sealing performance between the cylinder member and the piston member can be easily enhanced, and, between the cylinder member and the piston member can be made unnecessary bearing structure such as a thrust metal.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention shown in the drawings will be described below. In FIG. 1, a camshaft 2 is provided on a cylinder head 1 of a multi-cylinder diesel engine having a unit injector in which a fuel injection pump and a fuel injection valve are integrated and an operation of the fuel injection valve is controlled by an electromagnetic actuator. Each cam bracket 3
A first helical spline portion 5 inclined in one direction and a second helical spline inclined in the same direction as the first helical spline portion 5 are rotatably supported by the gear bracket 4 and the outer peripheral surface of the camshaft 2. Part 6 and the first
A third helical spline section 7 that crosses the second helical spline section 6 is formed in a direction opposite to the helical spline section 5, and a piston is provided at an end of the camshaft 2 adjacent to the first helical spline section 5. 8 is fixed.

Further, a cam gear 9 having a helical spline portion in the same direction as the inner hole is fitted into the first helical spline portion 5 of the camshaft 2, and the cam gear 9 extends in the axial direction of the camshaft 2 as described later. The displacement is constrained, and the rotational force transmitted from the engine crankshaft (not shown) to the cam gear 9 via the idle gear and the like causes the camshaft 2 to rotate.
Is adapted to be rotated in the direction of arrow A, and a piston 8 is fitted into a hydraulic cylinder 10 formed inside the cam gear 9 to form a hydraulic actuator 11 by the piston 8 and the hydraulic cylinder 10. The camshaft 2 can be displaced in the axial direction by the operation of the hydraulic actuator 11.

On the other hand, each of the second helical spline portions 6 of the camshaft 2 is fitted with an engine cylinder intake / discharge cam body 12 having a helical spline portion having the same direction in an inner hole. A roller 16 of an intake valve driving rocker 15 and a roller 18 of an exhaust valve driving rocker 17 are pressed against an intake valve cam 13 and an exhaust valve cam 14 formed at 12, respectively.

Each of the third helical spline portions 7 of the camshaft 2 is fitted with a unit injector cam body 19 for each engine cylinder having a helical spline portion having the same direction in the inner hole. Rollers 22 of a unit injector drive locker 21 are pressed against unit injector cams 20 formed at 19 respectively.

At this time, the suction / discharge cam main body 12 and the unit injector cam main body 19 are in contact with each other, and the thrust metal 3 ′ provided on both side end surfaces of the cam bracket 3 or the side end surface of the gear bracket 4 respectively. By slidably contacting the provided thrust metal 4 ', the displacement of the camshaft 2 in the axial direction is restricted, and each range S shown in FIG. 1 corresponds to each cylinder.

As shown in FIG. 2, the first helical spline portion 5 in the axial direction of the camshaft 2 is provided.
Is β1, the inclination angle of the second helical spline section 6 is β2, the inclination angle of the third helical spline section 7 is β3, the pitch circle diameter in the first helical spline section 5 is D1, and the second helical spline is Assuming that the pitch circle diameter in the portion 6 is D2 and the pitch circle diameter in the third helical spline portion 7 is D3, the camshaft 2 and the cam gear 9
The relative rotation angle α1 (degree) between And the relative rotation angle α2 (degree) between the camshaft 2 and the suction / discharge cam main body 12 is: And the relative rotation angle α3 (degree) between the camshaft 2 and the unit injector cam body 19 is Where α1 = α2, that is, equation (1) and equation (2)
From the formula, Is set to hold.

As shown in detail in FIG.
The cam gear 9 slidably abuts a thrust metal 30 provided on a side end surface of the gear bracket 4 and slidably abuts a thrust metal 33 of a thrust bearing 32 fixed to a casing 31 to form a camshaft. 2
Of the piston 8 from the outside through annular inner grooves 34 and 35 formed in the thrust bearing 32 and oil passages 36 and 37 formed in the wall surface of the cam gear 9. The hydraulic actuator 1 is supplied with pressure oil as shown by arrows X and Y, and slides a piston 8 in the hydraulic cylinder 10 in the axial direction of the camshaft 2.
By the operation of 1, the camshaft 2 can be displaced in its axial direction.

Next, the operation and effect of the above device will be described. When the camshaft 2 is displaced by L in the axial direction, for example, leftward in FIG. 1 by the above operation of the hydraulic actuator 11, the camshaft 2 and the cam gear 9 are fitted into the first helical spline portion 5, so that the camshaft 2
Is rotated relative to the cam gear 9 in the advance direction of the arrow A by an angle α1, and the fitting of the camshaft 2 and the suction / discharge cam body 12 in the second helical spline portion 6 causes the suction / discharge cam main body 12 to rotate. Arrow A for 2
However, as described above, α1 = α2, and the rotation angle α1 of the camshaft 2 and the rotation angle α2 of the suction / discharge cam main body 12 are offset. As a result, the rotation phase of the suction / discharge cam main body 12 with respect to the cam gear 9 does not change at all, and accordingly, the suction / discharge cam main body 12
The rotation phases of the intake valve cam 13 and the exhaust valve cam 14 formed at the same time are always kept constant with respect to the cam gear 9.

On the other hand, as described above, by fitting the camshaft 2 and the cam gear 9 in the first helical spline portion 5, the camshaft 2 is rotated by an angle α1 in the advance direction of the arrow A with respect to the cam gear 9. However, due to the fitting of the camshaft 2 and the unit injector cam body 19 in the third helical spline section 7, the unit injector cam body 19
The unit injector cam body 19 is rotated relative to the cam gear 9 in the direction of arrow A by an angle α = α1 + α3, that is, (1).
From equation (3) and equation (3), And the unit injector cam 20 formed on the unit injector cam main body 19 is advanced by the angle α (degree).

When the camshaft 2 is displaced by L in the axial direction, for example, rightward in FIG. 1 by the action of the hydraulic actuator 11, it acts in the completely opposite manner as described above and is formed on the suction / discharge cam main body 12. The rotation phases of the intake valve cam 13 and the exhaust valve cam 14 are always kept constant with respect to the cam gear 9, but the unit injector cam 20 formed on the unit injector cam main body 19 is delayed by the angle α. .

That is, if the camshaft 2 is appropriately displaced in the axial direction by the action of the hydraulic actuator 11, the rotational phases of the intake valve cam 13 and the exhaust valve cam 14 are always kept constant with respect to the cam gear 9. As it is, the unit injector cam 20 can be advanced or retarded appropriately, so that when the unit injector is driven from the unit injector cam 20 via the roller 22 and the rocker 21, the unit injector cam 20 is substantially trapezoidally fed with respect to the crank angle. If the oil rate pattern is advanced or retarded as needed, and the fuel injection timing in the unit injector is appropriately selected, the fuel injection timing and the oil feed rate can be controlled independently, and the combustion characteristics of the engine, for example, Improvement of combustion efficiency during high-speed operation of the engine, Jin it is possible to easily realize the reduction of NOx and combustion noise in the exhaust during the idle operation.

The cam gear 9 and the hydraulic actuator 1
One hydraulic cylinder 10 is integrated, and the entire structure of the cam gear 9 and the hydraulic actuator 11 can be easily reduced in size and weight. Therefore, the surrounding space is limited, especially as in a diesel engine for vehicles. The benefits are great.

Further, since the cam gear 9 and the hydraulic cylinder 10 of the hydraulic actuator 11 are integrated, the rotation phase of the unit injector cam 20 with respect to the camshaft 2 is constant, and the camshaft 2 and the cam gear 9 rotate at the same speed. During normal operation of the diesel engine 1
There is no relative displacement between the piston 8 and the hydraulic cylinder 10 in the hydraulic actuator 11, and it is extremely difficult to control the rotation phase of the unit injector cam 20 with respect to the camshaft 2 during operation of the diesel engine 1. Piston 8 which is temporary and thereby
The relative displacement between the hydraulic cylinder 10 and the hydraulic cylinder 10 is relatively small, so that the sealing performance and durability between the outer peripheral surface of the piston 8 and the inner peripheral surface of the hydraulic cylinder 10 can be easily increased, and at the same time, the piston It is not particularly necessary to provide a bearing structure such as a thrust metal between each side face of the hydraulic cylinder 8 and each end face of the hydraulic cylinder 10 opposed thereto or a stopper of the piston 8 (not shown). A simple configuration can be achieved.

When the camshaft 2 rotates in the direction of the arrow A, the intake and exhaust cam main body 12 has a thrust force F1 to the right in FIG.
On the other hand, a large thrust force F2 acts to the left of FIG. 1 on each unit injector cam body 19 at the time of fuel injection due to the fitting at the helical spline portion 7,
The thrust force F1 acting on each intake / discharge cam main body 12 is supported by the thrust metal 3 'on the side end surface of the cam bracket 3 or the thrust metal 4' on the side end surface of the gear bracket 4, and is applied to each unit injector cam main body 19. The acting thrust force F2 is supported by the thrust metal 3 'on the side end surface of the cam bracket 3.

On the other hand, the fitting in the helical spline portion 7 causes a reaction on the camshaft 2 during fuel injection as shown in FIG.
A large thrust force F2 acts on the right side of FIG. 1 and a particularly large thrust force F3 on the right side of FIG. Works, so Figure 1
As shown in the figure, the thrust force (F
2 + F3) acts, so that it is necessary to apply a pressing force (F2 + F3) to the piston 8 to the left in FIG. Since the thrust force F1 acting on the camshaft 2 as a reaction of the thrust force F1 acting on each intake / discharge cam main body 12 is much smaller than the thrust force F2, this is ignored.

Therefore, as a reaction, the hydraulic cylinder 1
1, a pressing force (F2 + F3) acts to the right in FIG. 1, but the fitting in the helical spline portion 5 causes a thrust force F3 to act on the cam gear 9 to the left in FIG. Since the force F3 is supported by the side end surface of the gear bracket 4 via the thrust metal 30, in the cam gear 9 integrated with the hydraulic cylinder 10, the pressing force F3 of the pressing force (F2 + F3) and the gear bracket 4 The thrust force F3 applied to the side end face is canceled, and therefore, the remaining pressing force F2 acting on the cam gear 9
Is the thrust bearing 32 through the thrust metal 33
Supported by

In this case, the thrust force F2 is equal to the thrust force F
Thrust bearing 3
2 can be easily reduced, and the thrust bearing 32 can be easily downsized.

Also, hydraulic pressure is guided from outside to both surfaces of the piston 8 through annular inner grooves 34 and 35 formed in the thrust bearing 32 and oil passages 36 and 37 formed in the wall surface of the cam gear 9, respectively. It is not necessary to machine the oil passage for operating the hydraulic actuator 11 on the long camshaft 2 and the oil passage may be formed in the relatively small cam gear 9 and the thrust bearing 32. A practical effect that only a small amount is required is obtained.

In the above embodiment, a cam gear is used as a drive member for transmitting a rotational force to the camshaft. However, the cam gear may be replaced with a cog belt or a pulley or a sprocket to which a rotational force is applied by a chain. Needless to say.

[0026]

According to the cam control device for an engine according to the present invention, the cylinder member of the actuator is formed by at least a part of the drive member for transmitting the rotational force to the camshaft, and the cylinder member is integrated with the drive member. , The cam control device of the engine including the actuator can be easily reduced in size, and the cylinder member formed by at least a part of the driving member for rotating the cam shaft And the piston member connected to the camshaft and fitted into the cylinder member does not normally rotate relative to each other, so that the sealing performance between the cylinder member and the piston member can be easily improved, and There is no need for a bearing structure such as thrust metal between the cylinder and piston members, simplifying the structure of the actuator. It can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part in an embodiment of the present invention.

FIG. 2 is a partial structural explanatory view of the embodiment.

FIG. 3 is an enlarged longitudinal sectional view of a main part of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Camshaft 3 Cam bracket 4 Gear bracket 5 1st helical spline part 6 2nd helical spline part 7 3rd helical spline part 8 Piston 9 Cam gear 10 Hydraulic cylinder 11 Hydraulic actuator 12 Suction and discharge cam main body 13 Cam for intake valve 14 Exhaust valve cam 19 Unit injector cam body 20 Unit injector cam 32 Thrust bearing 34, 35 Inner groove 36, 37 Oil passage

Claims (2)

[Claims] 1. A driving member fitted to an outer peripheral surface of a camshaft by a helical spline portion and transmitting a rotational force to the camshaft, and an actuator for displacing the camshaft in an axial direction thereof, wherein the actuator is ,
A cylinder member formed by at least a part of the drive member and rotating integrally with the drive member; a piston member connected to the camshaft and fitted in the cylinder member; An engine cam control device including an urging means for displacing the cam shaft in an axial direction. 2. The device according to claim 1, wherein the biasing means is a hydraulic operating means for displacing the piston member by hydraulic pressure, and is formed on a bearing member for supporting the driving member on an engine body and on the driving member, respectively. An engine cam control device configured to guide the oil pressure into the cylinder member through an oil passage.