JP2004300976A - Variable valve system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform cooperation control of the control of a valve lift and an angle of action, and the control of valve timing, and to vary the relationship between the control of the valve lift and the angle of action, and the control of valve timing. <P>SOLUTION: An variable valve system 10 comprises a control shaft 2 for varying the amount of lift and the angle of action in the intake/exhaust valve of an internal combustion engine while being moved in the axial direction of a control shaft by an actuator; and a helical gear 13 for cooperation that is engaged to a cam shaft 1 by a helical spline 15, is mechanically interlocked to the travel in the axial direction of the control shaft 2, is moved in the axial direction of the cam shaft, and changes the rotary phase of the cam shaft 1 for varying valve timing (1). The variable valve system 10 also has a drive member 23 in an axial direction that is engaged to the helical gear 13 for cooperation by a second helical spline 24 and can travel in the direction of the cam shaft independently from the travel in the axial direction of the control shaft 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable valve mechanism for an internal combustion engine, and more particularly to a variable valve mechanism in which a variable valve lift mechanism and a variable valve timing mechanism (hereinafter, also referred to as a VVT system) are mechanically coordinated.
[0002]
[Prior art]
Japanese Patent Laying-Open No. 2001-263015 discloses a conventional variable valve mechanism of an internal combustion engine which includes both a variable valve lift mechanism and a VVT system independently of each other.
In the variable valve mechanism disclosed in Japanese Patent Application Laid-Open No. 2001-263015, as shown in FIGS. 4 to 6, the variable valve lift mechanism controls a control shaft 2 provided in parallel with a camshaft 1 by an actuator 3 in a control shaft axial direction. The slider 5 accommodated in the arm assembly 4 is moved in the axial direction of the control shaft, and the center (central arm) 4a and both ends of the arm assembly 4 are moved by the action of the helical spline formed on the slider 5. (Both arms) Change the relative angle with 4b. The cam 1a of the camshaft pushes the roller 6 of the central portion 4a to swing the central portion 4a, and pushes the roller of the roller rocker 8 with the beaks 7 of both ends 4b that swing together with the central portion 4a to stroke the intake / exhaust valve 9. . By moving the control shaft 2 in the axial direction, the relative angle between the central portion 4a and both ends 4b is changed, and the swing amount of the roller rocker 8 is changed to change the valve lift and the working angle.
In the variable valve mechanism disclosed in Japanese Patent Application Laid-Open No. 2001-263015, an actuator 50 for a VVT system is provided at the end of the camshaft 1 separately from the actuator 3 for driving the control shaft 2 of the variable valve lift mechanism. The valve timing is changed by changing the phase of the camshaft 1 by the actuator 50.
[0003]
[Patent Document 1]
JP 2001-263015 A
[Problems to be solved by the invention]
However, the above prior art has the following problems.
In the above prior art, the control of the valve lift and the valve operating angle by the variable valve lift mechanism and the valve timing control by the VVT system are performed independently of each other. When it is desired to have the relationship, each must be controlled so as to have the certain relationship.
In the case of hydraulic control, the above control may not be performed before the hydraulic pressure reaches a predetermined pressure, such as during a cold start.
SUMMARY OF THE INVENTION An object of the present invention is to provide a variable valve mechanism capable of performing cooperative control of valve lift, operating angle control, and valve timing control.
Another object of the present invention is to provide a variable valve mechanism capable of always performing the above-mentioned cooperative control regardless of the hydraulic pressure.
It is still another object of the present invention to provide a variable valve mechanism in which the relationship between valve lift, operating angle control, and valve timing control is variable.
[0005]
[Means for Solving the Problems]
The present invention that achieves the above object is as follows.
(1) a control shaft which is moved in an axial direction of the control shaft by an actuator to change a lift amount and a working angle of intake and exhaust valves of the internal combustion engine;
A cooperative helical gear that engages with the camshaft by a helical spline and moves in the camshaft axial direction mechanically in conjunction with the axial movement of the control shaft to change the rotational phase of the camshaft to vary the valve timing. When,
Variable valve mechanism with.
(2) an axial drive member that engages with the cooperative helical gear by a second helical spline and is movable in the camshaft axial direction independently of the axial movement of the control shaft; 2. The variable valve mechanism according to claim 1, wherein the rotation phase of the camshaft can be changed independently of the operation of the control shaft by moving the member by a second actuator.
[0006]
In the variable valve mechanism of the above (1), since the cooperative helical gear is provided, when the control shaft moves in the axial direction, the rotational phase of the camshaft can be changed in conjunction with the axial movement of the control shaft. The control of the valve lift and the operating angle and the control of the valve timing by the change of the rotation phase of the camshaft can be changed with a certain relationship, that is, the control can be coordinated.
Further, since the axial movement of the control shaft and the change in the rotational phase of the camshaft are mechanically linked, the cooperative control is always performed regardless of the hydraulic pressure.
In the variable valve mechanism of the above (2), since the cooperative helical gear and the axial drive member engaged with the second helical spline are provided, by moving the axial drive member by the second actuator, The relationship between the control of the valve lift and the operating angle and the valve timing control in the cooperative control can be changed.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a variable valve mechanism according to the present invention will be described with reference to FIGS. 4 to 6, a portion related to the control of the valve lift and the operating angle of the variable valve lift mechanism is also applied to the present invention. Applicable parts are given the same reference numerals in FIG. 1 as in FIGS. 4 to 6.
[0008]
As shown in FIG. 1, the variable valve mechanism 10 of the present invention includes a variable valve lift mechanism 11 having a structure similar to the conventional one, and a VVT system part 12 newly provided in the present invention.
[0009]
The variable valve lift mechanism 11 has a control shaft (first control shaft) 2 that is moved in the axial direction of the control shaft by the actuator 3 to change the lift amount and operating angle of the intake and exhaust valves 9 of the internal combustion engine. The variable valve lift mechanism 11 moves in the axial direction together with the first control shaft 2, the arm assembly 4 having a central portion (central arm) 4 a and both ends (both ends arms) 4 b, and the first control shaft 2. And a slider 5 for changing the relative angle between the central portion 4a and the both end portions 4b of the arm assembly 4 by a helical spline cut on the outer periphery when the arm assembly 4 is moved. The cam 1a of the camshaft pushes the roller 6 of the central portion 4a to swing the central portion 4a, and pushes the roller of the roller rocker 8 with the beaks 7 of both ends 4b that swing together with the central portion 4a to stroke the intake / exhaust valve 9. .
[0010]
When the first control shaft 2 moves in the axial direction, the relative angle between the central portion 4a and both ends 4b changes, the swing amount of the roller rocker 8 changes, and the valve lift and the working angle change. At this time, since the rotation angle of the camshaft 1 with respect to the first control shaft 2 does not change, the nose phase of the camshaft 1 remains fixed. FIG. 2 shows a valve lift-phase characteristic of the variable valve lift mechanism portion 11 of the present invention in which the valve lift and the operating angle are variable while the nose phase of the camshaft 1 is fixed.
[0011]
The VVT system part 12 is mechanically linked to the variable valve lift mechanism part 11. The VVT system portion 12 includes a helical gear 13 for cooperation. The cooperation helical gear 13 is engaged with the camshaft 1 (the outer periphery of the member 14 attached to the end of the camshaft 1) by a helical spline 15, and mechanically interlocks with the axial movement of the first control shaft 2. It is moved in the direction of the camshaft to change the rotation phase of the camshaft 1 with respect to the first control shaft 2 to make the valve timing variable.
[0012]
The VVT system portion 12 further includes a second control shaft 16 connected to the first control shaft 2 and a fixed support for slidably supporting the second control shaft 16 in the axial direction of the second control shaft 16. A second control; a wall 17, outer and inner peripheral bearings 19 for supporting the fixed wall 17 between the chain sprocket 18 and the camshaft 1 and permitting the rotation of the chain sprocket 18 and the camshaft 1 relative to the fixed wall 17; An axially movable non-rotating member 20 that transmits the axial movement of the shaft 16 to the cooperating helical gear 13, and an axial direction of the non-rotating member 20 while permitting relative rotation between the non-rotating member 20 and the cooperating helical gear 13. A bearing 21 for transmitting the movement to the helical gear 13 for cooperation.
[0013]
When the first control shaft 2 moves in the axial direction, the second control shaft 16, the non-rotating member 20, the bearing 21, and the cooperating helical gear 13 move in the axial direction by the same amount, and by a predetermined angle determined by the helical spline 15. , The camshaft 1 rotates, and the phase of the nose of the cam with respect to the first control shaft 2 changes. As a result, as shown in FIG. 3 (property of the present invention), the valve lift-phase characteristic is such that the phase changes with a predetermined relationship with the valve lift change, and the valve lift, both the valve operating angle and the valve timing change. -Change to phase characteristics.
In the above mechanism, when the first control shaft 2 moves in the axial direction, the cooperative helical gear 13 also moves in the axial direction due to mechanical interlock, and the valve timing changes regardless of the oil pressure. Further, the change in the valve timing, the change in the valve lift, and the change in the operating angle have a fixed relationship determined by the helical spline 15.
[0014]
In order to make the relationship between the change in the valve timing and the change in the valve lift and the operating angle variable, that is, so that the characteristics of the solid line can be changed to the characteristics of the broken line in FIG. Further, it is desirable to provide the following third portion 22.
The third portion 22 changes the phase of the cam nose by rotating the cooperative helical gear 13 and the camshaft 1 integrally while the first control shaft 2 is stopped in the axial direction. In this case, the relative rotation between the first control shaft 2, the cooperative helical gear 13, and the camshaft 1 is released by the bearing 21.
[0015]
The third portion 22 has an axial driving member 23 that is driven in the camshaft axial direction by hydraulic pressure or electric power. In the illustrated example, the case of hydraulic drive is shown, and the case where the axial drive member 23 is a hydraulic piston is shown. However, the present invention is not limited to the hydraulic piston, and may be an electrically driven member.
The axial driving member 23 is engaged with the cooperating helical gear 13 and the second helical spline 24, and is movable in the camshaft axial direction independently of the axial movement of the first control shaft 2, and is movable in the axial direction. The rotational phase of the camshaft 1 can be changed independently of the operation of the first control shaft 2 by moving the drive member 23 by the second actuator 25 (in the illustrated example, a hydraulic actuator is used, but may be electrically operated). And
[0016]
When the axial driving member 23 is used as one element of a driving force transmitting member from the chain sprocket 18 to the camshaft 1, the axial driving member 23 is connected to the chain sprocket 18 by a spline 26. The spline 26 may be a straight spline or a helical spline. However, the driving force may be transmitted from the chain sprocket 18 to the camshaft 1 without passing through the axial driving member 23.
[0017]
When the camshaft axial driving of the axial driving member 23 is performed by hydraulic pressure, the axial driving member 23 is a hydraulic piston, and the hydraulic piston 23 (the hydraulic piston is denoted by 23 because it is the same member as the axial driving member). ) Are provided on both sides in the axial direction, and the hydraulic pressure to the hydraulic chambers 27 and 28 is switched by an oil control valve (OCV) 29. In the illustrated example, the supply of hydraulic pressure from the oil control valve 29 to the hydraulic chamber 27 is guided to the camshaft end chamber 32 through the passage 30 and the camshaft passage 31, and from there to the hydraulic chamber 27 through the spline 26. ing. The supply of the hydraulic pressure from the oil control valve 29 to the hydraulic chamber 28 is guided to the hydraulic chamber 28 via the passage 33 and the camshaft passage 34.
The hydraulic piston and the hydraulic chambers 27 and 28 constitute a second actuator 25.
[0018]
When the hydraulic pressure is switched by the oil control valve 29 and the hydraulic pressure in the hydraulic chambers 27 and 28 is switched, the camshaft of the axial drive member 23 is driven in the axial direction, and the first control shaft 2 is stopped in the axial direction, and the helical for cooperation is used. The gear 13 and the camshaft 1 are rotated integrally, and the phase of the cam nose changes. As a result, the cam lift and the operating angle characteristics move right and left in FIG. 3, the phase of the cam nose changes, the valve timing becomes variable, and therefore, the adjustment becomes possible.
[0019]
Next, the operation of the present invention will be described.
In the variable valve mechanism 10 of the present invention, since the cooperative helical gear 13 is provided, when the first control shaft 2 moves in the axial direction, the rotation phase of the cam nose of the camshaft 1 can be changed in conjunction with the movement. The control of the valve lift and the operating angle by the axial movement of the first control shaft 2 and the control of the valve timing by the change in the rotation phase of the camshaft 1 are changed with a fixed relationship determined by the helical spline 15, that is, the coordination is performed. Can be controlled. Conventionally, two independent actuators were provided, and each of the actuators had to be controlled so that the control of the valve lift, the operating angle, and the valve timing control cooperated. However, in the present invention, as shown in FIG. In addition, the control of the valve lift, the operating angle, and the valve timing control automatically cooperate with a certain relationship.
[0020]
The axial movement of the first control shaft 2 and the change in the rotational phase of the camshaft 1 are mechanically linked via the second control shaft 16, the non-rotating member 20, the bearing 21, and the helical gear 13 for cooperation. Therefore, the cooperative control is performed mechanically regardless of the hydraulic pressure. Therefore, even when the hydraulic pressure is not sufficiently increased, such as at the time of a cold start, the cooperative control is reliably performed. On the other hand, conventional valve lift, operating angle control, and valve timing control may not be performed when the hydraulic pressure is not increased.
[0021]
When the variable valve mechanism 10 includes the axial driving member 23 that engages with the cooperative helical gear 13 and the second helical spline 24, the axial driving member 23 is connected to the second actuator 25. By moving the camshaft in the axial direction, the relationship between the control of the valve lift and the operating angle and the valve timing control in the cooperative control can be changed. Thereby, the valve lift-phase characteristic moves right and left in FIG. 3, and the valve lift-phase characteristic can be freely changed in the direction between the solid line and the broken line in FIG. As a result, the degree of freedom in controlling the valve variable characteristics (lift, operating angle, and valve timing) can be increased.
For example, when the lift control is performed, the timing changes to the retard side. However, the third portion 22 can cancel the changed timing to the retard side. As a result, valve lift and duration control can be controlled independently of valve timing control.
[0022]
【The invention's effect】
According to the variable valve mechanism of the first aspect, since the cooperative helical gear is provided, when the first control shaft moves in the axial direction, the rotation phase of the camshaft can be changed in conjunction with the first control shaft. The control of the valve lift and the operating angle by the axial movement of the control shaft and the control of the valve timing by the change in the rotation phase of the camshaft can be changed with a certain relationship, that is, the cooperative control can be performed.
Further, since the axial movement of the first control shaft and the rotation phase change of the camshaft are mechanically linked, the cooperative control is always performed regardless of the hydraulic pressure.
According to the variable valve mechanism of the second aspect, the variable valve mechanism further includes the axial driving member that engages with the cooperative helical gear and the second helical spline. By moving the actuator with the actuator, the relationship between the control of the valve lift and the operating angle in the cooperative control and the valve timing control can be made variable.
[Brief description of the drawings]
FIG. 1 is a sectional view of a variable valve mechanism according to the present invention.
FIG. 2 is a valve lift, operating angle-phase characteristic diagram of only a variable valve lift mechanism in the variable valve mechanism of the present invention.
FIG. 3 is a valve lift, operating angle-phase characteristic diagram of the variable valve mechanism of the present invention. The solid line is a valve lift and operating angle-phase characteristic diagram for both the variable valve lift mechanism portion and the VVT system portion, and the dashed line is a valve lift and operating angle-phase characteristic diagram when a third portion is further provided.
FIG. 4 is a plan view of a variable valve mechanism disclosed in Japanese Patent Application Laid-Open No. 2001-263015. The variable valve lift mechanism is applicable to the present invention.
5 is a perspective view of a first control shaft and an arm assembly of a variable valve lift mechanism in FIG. 4; This part is also applicable to the present invention.
FIG. 6 is a front view of a first control shaft, an arm assembly, a cam shaft, a roller rocker, and an intake / exhaust valve of a variable valve lift mechanism in FIG. 4; This part is also applicable to the present invention.
[Explanation of symbols]
Reference Signs List 1 camshaft 1a cam 2 first control shaft 3 actuator 4 system arm assembly 4a central part (central arm)
4b Both ends (both arms)
Reference Signs List 5 Slider 6 Roller 7 Beak 8 Roller rocker 9 Intake / exhaust valve 10 Variable valve mechanism 11 Variable valve lift mechanism part 12 VVT system part 13 Helical gear for coordination 14 Camshaft end mounting member 15 (First) helical spline 16 2 control shaft 17 fixed wall 18 chain sprocket 19 outer and inner bearings 20 non-rotating member 21 bearing 22 third part 23 axial drive member (for example, hydraulic piston)
24 second helical spline 25 second actuator 27, 28 hydraulic chamber 29 oil control valve 30, 33 passage 31, 34 camshaft passage 32 camshaft end chamber

Claims (2)

A control shaft that is moved in an axial direction of the control shaft by an actuator to vary a lift amount and a working angle of intake and exhaust valves of the internal combustion engine;
A cooperative helical gear that engages with the camshaft by a helical spline and moves in the camshaft axial direction mechanically in conjunction with the axial movement of the control shaft to change the rotational phase of the camshaft to vary the valve timing. When,
Variable valve mechanism with. An axial drive member engaged with the cooperative helical gear with a second helical spline and movable in the camshaft axial direction independently of the axial movement of the control shaft; 2. The variable valve mechanism according to claim 1, wherein the rotation phase of the camshaft can be changed independently of the operation of the control shaft by being moved by the second actuator.

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