JP3344258B2 - Engine camshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In order to adjust the injection timing of a unit injector without affecting the opening / closing timing of intake / exhaust valves in an engine, Japanese Patent Laid-Open Publication No.
The technique described in Japanese Patent Publication No. 04-2004 is conventionally known.
That is, in this case, the straight spline and the helical spline are formed so as to intersect with each other on the outer peripheral surface of the spline shaft which is the camshaft, and the straight spline hole of the valve cam unit having the intake / exhaust valve driving cam is formed as described above. By fitting the helical spline hole of the injector cam unit provided with the unit injector driving cam with the helical spline of the spline shaft, and displacing the spline shaft in the axial direction by driving the actuator, together with the straight spline of the spline shaft. The rotation phase of the unit injector driving cam in the injector cam unit is advanced or delayed with respect to the rotation phase of the intake / exhaust valve driving cam in the valve cam unit. , And adjusts the injection timing of the unit injector.

However, in the case of a multi-cylinder engine, it is necessary to sequentially fit the injector cam unit knit for each cylinder on the camshaft so as to have a predetermined phase difference. However, the injector cam unit knit is fitted to a helical spline. When the injector cam unit itself is displaced in the axial direction along the spline shaft, the injector cam unit itself rotates and changes its rotation phase. Therefore, if the phase difference is to be absorbed by the shape of each injector cam unit, the same cam is used. Injector cam units with different phases in the profile are required by the number of cylinders, which increases the number of engine parts.Therefore, the valve cam unit is mounted on the cam shaft by fitting helical splines. Injector As with the Muyunitto, different valve cam unit phase difference in the identical cam profiles must be prepared by the cylinder number, the further number of parts is increased.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the number of required cam types by making it possible to easily control the rotational phase of a cam on a camshaft of an engine.

[0005]

Therefore, in the camshaft of the engine according to the present invention, a cam member for the same purpose, which is fitted to the outer peripheral surface of the shaft portion by the helical spline portion, is inserted from the end of the shaft portion. The rotation angle θ ° when the cam member is displaced by one pitch of the engine cylinder on the shaft portion is set to “360 ° /
The number of engine cylinders ”is an integer multiple of γ °, and the circumferential spline pitch angle δ ° of the helical spline portion is a divisor of the rotation angle θ °.

Therefore, when each cam member having the same purpose is inserted from the end of the camshaft shaft to dispose it for each engine cylinder, the cam member is displaced by one pitch of the engine cylinder on the camshaft shaft. Rotation angle θ °
Is an integral multiple of the angle γ ° related to the number of engine cylinders, and the spline pitch angle δ ° of the helical spline portion is a divisor of the rotation angle θ °. Each cam member is inserted into the helical spline portion from an end thereof at a predetermined rotation phase corresponding to the spline pitch angle δ °, and each cam member is appropriately fitted to each engine cylinder while being fitted to the helical spline portion. By displacing to the position of the outer peripheral surface of the camshaft shaft portion, each cam member is arranged at a predetermined phase angle on the camshaft shaft portion.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described. In FIG. 1, a camshaft is provided on a cylinder head 1 of a multi-cylinder 4-cycle 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. 2 is rotatably supported by each of the cam brackets 3 and the gear brackets 4, and a first helical spline portion 5 inclined in one direction is provided on the outer peripheral surface of the shaft portion 2 ′ of the camshaft 2.
A second helical spline section 6 inclined in the same direction as the first helical spline section 5;
And a third helical spline portion 7 intersecting with the second helical spline portion 6 is formed, and the camshaft shaft portion 2 ′ is connected to a hydraulic actuator 10 including a hydraulic cylinder 8 and a piston 9. The camshaft 2 can be displaced in the axial direction by the hydraulic actuator 10.

A cam gear 11 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 shaft portion 2 ', thereby displacing the camshaft 2 in the axial direction. Is restrained, and the camshaft shaft portion 2 ′ is rotated in the direction of arrow A by the rotational force transmitted from the engine crankshaft (not shown) to the cam gear 11 via the idle gear and the like.

On the other hand, each of the second helical spline portions 6 of the camshaft shaft portion 2 'is provided with an intake cam main body 12 and an exhaust cam main body 12' for an engine cylinder having a helical spline portion having an inner hole in the same direction. Mated,
An intake valve cam 13 and an exhaust valve cam 14 formed on the intake cam body 12 and the exhaust cam body 12 ', respectively.
The roller 16 of the intake valve driving rocker 15 and the roller 18 of the exhaust valve driving rocker 17 are pressed against each other.

Each of the third helical spline portions 7 of the camshaft shaft portion 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. A unit injector driving locker 21 is attached to a unit injector cam 20 formed in the injector cam body 19.
Rollers 22 are pressed against each other.

At this time, the intake cam main body 12 and the exhaust cam main body 12 ', and the intake cam main body 12 and the unit injector cam main body 19 have their respective bosses abutting each other, and have both end faces on the both sides of the cam bracket 3 respectively. Thrust bearing 3 ′ provided or thrust bearing 4 provided on one side end face of gear bracket 4.
′, The displacement of the intake cam main body 12, the exhaust cam main body 12 ′ and the unit injector cam main body 19 in the axial direction of the camshaft 2 is restrained, and the respective ranges S shown in FIG. Correspond to each cylinder.

As shown in FIG. 2, the first helical spline portion 5 in the axial direction of the camshaft 2 is provided.
, The inclination angle of the second helical spline section 6 is β2 °, and the inclination angle of the third helical spline section 7 is β
If the pitch circle diameter in the first helical spline section 5 is D1, the pitch circle diameter in the second helical spline section 6 is D2, and the pitch circle diameter in the third helical spline section 7 is D3, the hydraulic actuator 10 The relative rotation angle α1 ° between the camshaft 2 and the cam gear 11 with respect to the axial displacement amount L of the camshaft 2 due to the action of And the relative rotation angle α2 ° between the camshaft 2, the intake cam body 12, and the exhaust cam body 12 ′ is And the relative rotation angle α3 ° between the camshaft 2 and the unit injector cam body 19 is Where α1 ° = α2 °, that is, from equations (1) and (2), Is set to hold.

Further, in a four-cycle engine having n cylinders, each intake cam body 12, each exhaust cam body 12 ', or each unit injector cam body 19
The rotational phase difference between cam members (hereinafter simply referred to as “cam members”) each having the same purpose is 36
0 ° / n = γ ° and an integral multiple of γ °. As is clear from FIG. 3, the cam member is displaced by the cylinder pitch L1 in the axial direction of the camshaft 2 along the helical spline of the camshaft shaft portion 2 ′. If the cam member rotation angle at that time is θ °, Where m: spline module z: number of spline teeth β °: spline inclination angle However, the rotation angle θ ° is set to be an integral multiple of the angle γ °.

The spline pitch angle δ °, which is the circumferential rotation angle of one tooth of the helical spline, is δ ° = 360 ° / z (7), and the spline pitch angle δ ° is the rotation of the cam member. The angle is set to be a divisor of θ °.

In addition, as shown in FIG. 4, a blank width L0 between the cross helical splines X including the second helical spline portion 6 and the third helical spline portion 7 formed on the camshaft shaft portion 2 '. The camshaft 2 at each boss portion of the intake cam body 12, the exhaust cam body 12 ', and the unit injector cam body 19
The length is set to be smaller than the respective lengths L11, L12, and L13 in the axial direction.

Next, the operation of the above device will be described.
When the camshaft shaft portion 2 ′ is displaced in the axial direction by the action of the hydraulic actuator 10, for example, to the left in FIG. 1 by L, the camshaft shaft portion 2 ′ and the cam gear 11 are fitted in the first helical spline portion 5. As a result, the camshaft shaft portion 2 ′ is rotated by an angle α1 ° in the advance direction of the arrow A with respect to the cam gear 11, and the camshaft shaft portion 2 ′ of the second helical spline portion 6 and the intake cam body 12 And the exhaust cam main body 12 ′, the intake cam main body 12 and the exhaust cam main body 12 ′ are rotated by an angle α2 ° in a retard direction opposite to the arrow A with respect to the camshaft shaft 2 ′. As described above, α1 ° = α2 °, and as a result, the rotation angle α1 ° of the camshaft shaft portion 2 ′ and the rotation angle α2 ° of the intake cam body 12 and the exhaust cam body 12 ′ are offset. For cam gear 11 Intake cam body 12 and the rotational phase of the exhaust cam body 12 'becomes not change at all, therefore, the intake cam body 12 and the exhaust cam body 1
The rotation phases of the intake valve cam 13 and the exhaust valve cam 14 formed on the cam gear 11 are always kept constant.

On the other hand, as described above, the camshaft shaft portion 2 'and the cam gear 1 in the first helical spline portion 5
1, the camshaft shaft portion 2 'becomes the cam gear 11
Is rotated in the advance direction of the arrow A by an angle α1 °, but the unit injector cam main body 19 is fitted by the fitting of the camshaft shaft portion 2 ′ and the unit injector cam main body 19 in the third helical spline portion 7. Angle α3 in the advance direction of arrow A with respect to camshaft shaft portion 2 '
And the unit injector cam body 19 is angled with respect to the cam gear 11 in the direction of arrow A by α ° = α1 ° + α3 °, that is, from the expressions (1) and (3), And the unit injector cam 20 formed on the unit injector cam main body 19 is advanced by the angle α °.

Further, the camshaft shaft 2 'is moved in the axial direction by the action of the hydraulic actuator 10, for example, as shown in FIG.
Displaced to the right by L acts exactly the same as above,
The rotation phases of the intake valve cam 13 and the exhaust valve cam 14 formed on the intake cam body 12 and the exhaust cam body 12 ′ are always kept constant with respect to the cam gear 11. The formed unit injector cam 20 is delayed by the angle α °.

That is, if the camshaft shaft portion 2 ′ is appropriately displaced in the axial direction by the action of the hydraulic actuator 10, the rotation phases of the intake valve cam 13 and the exhaust valve cam 14 are always constant with respect to the cam gear 11. And the unit injector cam 20 can be advanced or retarded as appropriate, so that when the unit injector cam is driven from the unit injector cam 20 via the roller 22 and the rocker 21, the unit injector cam 20 moves with respect to the crank angle. By advancing or retarding the substantially trapezoidal oil transfer rate pattern as needed, and appropriately selecting the fuel injection timing in the unit injector, the fuel injection timing and the oil transfer rate can be controlled independently of each other.
It is possible to easily realize the combustion characteristics of the engine, for example, the improvement of the combustion efficiency at the time of high-speed operation of the engine, the reduction of NOx and the combustion noise in the exhaust at the time of idle operation of the engine, and the like.

Since each cam member is arranged for each engine cylinder, when each cam member is sequentially inserted into the cross helical spline X at one end from one end of the camshaft shaft portion 2 ', the cam member is The cam member rotation angle θ ° when displaced by the cylinder pitch L1 in the axial direction of
An integer multiple of the angle gamma °, and, together with the circumferential spline pitch angle [delta] ° of helical spline is a sub-multiple of the rotation angle theta °, the intake cam body 12, the exhaust cam body 12
And the length L1 of each boss of the unit injector cam body 19 in the direction of the camshaft 2 axes.
1, L12, and L13 are each set to be larger than the blank width L0 between the cross helical splines X, so that each cam member is rotated at a predetermined rotation phase with respect to the camshaft shaft 2 'at one end. If the helical spline X is inserted from the end of the helical spline X and displaced onto a predetermined cross helical spline X corresponding to each engine cylinder, each cam member is automatically arranged at an appropriate phase angle.

For example, in an in-line six-cylinder four-cycle engine, the firing order from the first cylinder to the sixth cylinder is the first, fifth, third, sixth, second, and second cylinders, respectively, as shown in FIG. As shown in FIG. 6, the first cylinder cam member has four cylinders and the rotational phase difference between the cam members for the same purpose is an integral multiple of γ ° = 360 ° / 6 = 60 °. a and the second cylinder cam member b are inserted into the cross helical spline X at the right end of the camshaft shaft portion 2 'in FIG. 5 from the right side in FIG. 5 and displaced to the left in FIG. Consider the case where the cylinder is arranged at an appropriate phase angle with respect to the cylinder.

The spline module m = 2.0 of the helical spline portion where the cam members a and b are fitted, the number of spline teeth z = 30, and the spline inclination angle β ° = 11.3236
If the cylinder pitch L1 is 160 mm, the cam member rotation angle θ ° when the cam member a is displaced by the cylinder pitch L1 in the axial direction of the camshaft shaft portion 2 ′ is (6)
From the formula, Therefore, the cam member b is fitted with the same rotational phase as that of the cam member a from the right end of the cross helical spline X on the right end of the camshaft shaft portion 2 'in FIG. 4 to a position corresponding to the second cylinder in FIG. If displaced to the left, the cam member b leads the cam member a by θ ° = 60 °.

On the other hand, as shown in FIG. 5, the cam member b must advance by 120 ° with respect to the cam member a, but the circumferential spline pitch angle δ ° is given by the following equation (7). 4 = 360 ° / 30 = 6 °, the cam member b is advanced from the rotational phase of the cam member a by (120 ° −60 °) / 6 ° = 5 splines, and the cross helical spline at the right end in FIG. If X is inserted from the right end of X and displaced to the left in FIG. 4 to a position corresponding to the second cylinder, the cam member b has an appropriate phase angle with respect to the cam member a, that is, a phase angle advanced by 120 °. Will be arranged.

In the same manner as above, the cam members for the other cylinders also have a rotational phase difference with respect to the first cylinder cam member a and a cam member rotation angle corresponding to the number of cylinder pitches from the cam member a. Based on the integral multiple of θ ° and the spline pitch angle δ °, the rotation phase of the cam member a is shifted by an appropriate number of splines, and FIG.
The right-hand cross helical spline X is inserted from the right end and displaced to the left in FIG. 4 to a position corresponding to each cylinder, thereby automatically disposing the cam member a at an appropriate phase angle. Can be done.

Therefore, since the rotation phase of each cam member fitted to the cross helical spline X can be controlled simply and reliably, each cam member can be easily shared for each cylinder, and the cam member to be prepared for the engine is provided. By reducing the number of types, the number of types of parts can be reduced, and as a result, their production costs can be reduced.

[0026]

According to the camshaft of the engine according to the present invention, each cam member having the same purpose is inserted into the helical spline portion of the camshaft shaft portion from the end with a predetermined rotation phase. By displacing the helical spline section to the position of the outer peripheral surface of the appropriate camshaft shaft section corresponding to each engine cylinder, each cam member can be reliably arranged at a predetermined phase angle on the camshaft shaft section. Therefore, it is possible to share the same shape of each cam member. Therefore, from this aspect, it is possible to reduce the number of engine parts to a minimum and to easily reduce the production cost. is there.

[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 explanatory diagram of a main part structure of the embodiment.

FIG. 4 is an exploded perspective view of a main part of the embodiment.

FIG. 5 is an operation explanatory view of the embodiment.

FIG. 6 is an explanatory diagram of a main part structure of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Camshaft 2 'Shaft 3 Cam bracket 4 Gear bracket 5 First helical spline 6 Second helical spline 7 Third helical spline 10 Hydraulic actuator 11 Cam gear 12 Intake cam main body 12' Exhaust cam main body 13 Intake Valve cam 14 Exhaust valve cam 19 Unit injector cam body 20 Unit injector cam β Spline inclination angle δ Spline pitch angle θ Cam member rotation angle L1 Cylinder pitch m Spline module z Number of spline teeth

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-172209 (JP, A) JP-A-53-102450 (JP, A) JP-A-6-272519 (JP, A) JP-A-6-272519 346710 (JP, A) JP-A-2-227506 (JP, A) JP-A 62-27223 (JP, U) JP-A 59-152104 (JP, U) JP-A 6-4454 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 1/00 F16H 53/02

Claims (1)

(57) [Claims] 1. A cam member for the same purpose, which is fitted to an outer peripheral surface of a shaft portion by a helical spline portion, is inserted from an end of the shaft portion and disposed for each engine cylinder, and the cam member is mounted on the shaft portion. Is an integer multiple of “360 ° / the number of engine cylinders” = γ °, and the circumferential spline pitch angle δ ° of the helical spline portion is An engine camshaft that is a divisor of the rotation angle θ °.