JPH10205315A - Variable valve lift device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve lift device capable of reliably switching the lifting amount. SOLUTION: This variable valve lift device is provided with an intake/ exhaust valve 24, an inner cam 22, outer cams 20 provided with a larger base circle and a nose, an outer lifter 26, an inner lifter 28 on which a groove 62 is formed, and a switching plate 70 to be slid in the direction perpendicular to a shaft of the intake/exhaust valve 24, to be moved together with the outer lifter, and to be in the position of the groove 62 when it is brought in contact with the base circle. A cam groove 11 is formed on the rear part side of the base circle of the inner cam, a control rod 12 inserted through the axial part so as to be vertically moved is provided on the inner lifter, and a lock member 14 to be vertically moved on the outer peripheral side of the groove 62 and for regulating the movement of the switching plate to the inside of the groove 62 is provided on the control rod.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve lift device of a valve lifter type for varying the opening / closing timing or lift amount of an intake / exhaust valve in order to adjust the intake / exhaust amount when the engine rotates at a low speed and at a high speed. It is.

[0002]

2. Description of the Related Art In an engine such as an automobile, the amount of intake / exhaust required immediately after the start of the engine and at low engine speed or low load is small, and the amount of intake / exhaust required at high engine speed or high load is small. More. Therefore, by controlling the opening / closing amount and operation timing of the intake / exhaust valves, an appropriate output of the engine and a reduction in fuel consumption are achieved.

[0003] As a highly durable variable valve lift device used for this purpose, the applicant of the present application has disclosed in Japanese Patent Laid-Open No. 8-189.
No. 316 (Japanese Patent Application No. 6-339198),
A method of switching between operation by a high-speed cam (outer cam) and operation by a low-speed cam (inner cam) using a plate that is moved by a hydraulic device has already been proposed.

That is, as shown in FIG. 13, a plate 91 which is moved by a hydraulic operation is engaged between an inner lifter 921 and an outer lifter 922, whereby the intake / exhaust valve 24 is driven by a high speed cam (outer cam 931). Drive. As a result, a lift characteristic shown by a curve 892 in FIG. 12 is obtained. Further, the engagement of the plate 91 between the inner lifter 921 and the outer lifter 922 is released, whereby the intake / exhaust valve 24 is driven by the low speed cam (the inner cam 932). As a result, a lift characteristic shown by a curve 891 in FIG. 12 is obtained. And the above engagement state is
The annular groove 6 provided in the inner lifter 921 by the plate 91
Switching is performed by moving to and from 20.

In the figure, reference numeral 941 denotes a spring for urging the intake (exhaust) air valve 24 in the closing direction, reference numeral 942 denotes a spring for urging the outer lifter 922 outward, and reference numeral 943 denotes an inner lifter 921 outward. Is a spring that urges the spring. The operation of the switching plate 91 is controlled by control means (not shown) by detecting the load or rotation speed of the engine.

[0006]

However, the operation of the switching plate 91 in the variable valve lift device, that is, the operation of switching the lift amount, is performed based on the state of the engine irrespective of the rotational phase of the cams 931 and 932. There is a problem that the operation of the switching plate 91 is unstable, in other words, it may be in an incomplete state.

That is, the lifters 921 and 922 are
In the state in which the outer lifter 922 and the inner lifter 921 are in contact with each other at a base circle, the difference in the movement speed between the outer lifter 922 and the inner lifter 921 (when disengaged) or the force acting between them (the load when engaged)
Does not occur, the movement of the switching plate 91 in the annular groove 620 is smooth. However, in other rotation phases, a difference in the movement speed (when disengaged) or a force acting between them (load during engagement) is generated between the outer lifter 922 and the inner lifter 921, and the switching plate 91 is rotated.
May stop in an incomplete state.

When the switching plate 91 is in such a halfway state, the load acting between the lifts 921 and 922 may cause the switching plate 91 to be disengaged from the annular groove 620 (the so-called lift amount). Switching mistake). Such a switching error not only causes a decrease in engine performance, but also causes wear and breakage of a switching mechanism such as a switching plate. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to reliably switch an inner lifter and an outer lifter to an engaged state by a switching member, to reliably switch the lift amount, and to improve durability. An object of the present invention is to provide a variable valve lift device having excellent performance.

[0009]

According to a first aspect of the present invention, there is provided an intake / exhaust valve which opens and closes a port by being moved up and down in an axial direction and is urged in a closing direction. An outer cam having a base circle and a nose larger than a base circle and a nose of the inner cam which are arranged in parallel with the inner cam, an outer lifter urged in a direction in which the outer cam comes into contact with the outer cam; An inner lifter which is in contact with the upper end surface of the intake / exhaust valve and has a groove formed in the outer periphery; and an inner lifter which slides in a direction perpendicular to the axis of the intake / exhaust valve and moves together with the outer lifter, and wherein the outer lifter is a base circle of the outer cam. And a control means for moving the switching member in a direction perpendicular to the axis of the intake / exhaust valve when the switching member is located at the position of the groove of the inner lifter. A high-lift mode in which the switching member is inserted into the groove to engage the inner lifter and the outer lifter to open and close the intake / exhaust valve in a high-lift state; In a variable valve lift device configured to be switchable between a low lift mode in which the outer lifter is engaged with an outer lifter to open and close in a low lift state, a cam groove is formed on a rear side of a base circle of the inner cam. The inner lifter is provided with a control rod which is inserted in the axial direction so as to be movable in a predetermined range in the axial direction and is urged upward. The control rod is provided with a cam groove of the inner cam. And the upper end of the inner lifter groove is moved up and down in accordance with the vertical movement of the control rod. In the variable valve lift device characterized by restricting possible locking member to move the switching member into the groove.

The switching operation of the lift characteristic in the variable valve lift device according to the present invention, that is, the change of the engagement state between the inner lifter and the outer lifter is the same as that of the conventional device. That is, by moving the switching member into and out of the groove of the inner lifter, the inner lifter and the outer lifter are engaged or disengaged, whereby the intake / exhaust valve is driven by the high speed cam (outer cam) or the low speed is driven. The intake and exhaust valves are driven by the cam (inner cam).

In the present invention, it should be particularly noted that, first, a cam groove is provided on the rear side of the base circle of the inner cam (the side that comes into contact with the inner lifter with a delay). And the upper end of the control rod is located at a position facing the cam groove of the inner cam and abuts against the base circle. Third, the upper end of the switching member of the inner lifter enters in accordance with the vertical movement of the control rod. A lock member that moves up and down on the outer peripheral side to regulate the movement of the switching member into the groove of the inner plate is provided.

Since the inner lifter is in contact with the rear side of the base circle of the inner cam and the upper end of the control rod is located at the position of the cam groove of the inner cam, The upper end of the control rod rises toward the cam groove, that is, toward the inside of the base circle. As a result, in conjunction with the control rod, the lock member rises on the outer peripheral side of the groove into which the switching member of the inner lifter enters, thereby suppressing the movement of the switching member. More specifically, in the first operation mode, that is, when the switching member does not enter the groove of the inner lifter and the inner lifter and the outer lifter are not engaged, the raised lock member is The switching member is prevented from entering the groove.

Therefore, the inner lifter contacts (or opposes, the same applies hereinafter) the rear side of the base circle of the inner cam.
In this case, the switching of the cam operated to determine the lift characteristic, that is, the switching of the lift characteristic (cam) is not performed. As a result, as described below, halfway switching (transition) of the switching member does not occur.

First, in the first operation mode, that is, when the switching member does not enter the groove of the inner lifter and the inner lifter and the outer lifter are not engaged, in the conventional device, the rear portion of the base circle is used. When the switching operation of the switching member is started on the side, the inner lifter shifts to the nose position of the inner cam (the position where the cam lift occurs) within a short time and therefore before the switching member is completely moved. Therefore, a displacement in the direction of causing a displacement or a displacement between the inner lifter and the outer lifter acts, the movement of the switching member is suppressed, and the switching member does not sufficiently enter the groove, and the switching member is in an incomplete switching state. Become.

However, in the variable valve lift device according to the present invention, when the inner lifter is in a phase in which the inner lifter is in contact with the rear side of the base circle of the inner cam, the control rod enters the cam groove and the lock member prevents the switching member from entering. Deter. Therefore, the switching of the cam, that is, the switching of the lift characteristic (cam) is not performed, and the incomplete transfer of the switching member into the groove as in the conventional device does not occur.

On the other hand, when a switching command is issued in a phase other than the above, that is, in a phase in which the inner lifter does not face the rear side of the base circle, a state in which the inner lifter is in contact with the front of the base circle, that is, the switching is performed. The switching operation is started when the member reaches the position facing the groove of the inner lifter (when the switching member can enter the groove). When the inner lifter is in contact with the center of the base circle and the movement of the lifter is stopped or at least slow, the switching member is moved, and the switching member is completely moved into the groove. The same applies to the above.)

As described above, according to the present invention, when the switching member is in the first operation mode, the movement of the switching member does not become incomplete, and the switching of the lift characteristics, that is, the switching between the inner lifter and the outer lifter is performed. The change to the engaged state is made completely. Further, the switching error of the lift characteristic as in the conventional device does not occur. Since the incomplete switching phenomenon does not occur, the wear of the switching member and the like is reduced.

According to a second aspect of the present invention, the lock member moves up and down along the outer peripheral surface of the groove of the inner lifter, thereby protruding into the side of the groove of the inner lifter or sinking below the side. This can be realized by providing an engaging piece that performs the operation (see Embodiment 1). That is, when the engaging piece projects to the side of the groove, for example, the first
In the mode, the engaging piece abuts on the front end of the rear portion of the switching member that enters the groove, and prevents the switching member from entering the groove.

Further, as described in claim 3, the switching member may be provided with a fitting groove in which the engaging piece is fitted at its forward (entering) position (see Embodiment 2). In the second operation mode, i.e., when the switching member has already entered the groove of the inner lifter and the inner lifter is engaged with the outer lifter, in the conventional apparatus, the switching member is located at the rear side of the base circle. When the switching operation is started, the inner lifter shifts to the nose position of the inner cam within a short period of time before the switching member completely retracts from the groove, and the inner lifter and the outer lifter During this time, a load acts to restrict the movement of the switching member, and the switching member is in an incomplete switching state, that is, in an incomplete switching state.

On the other hand, according to the invention of claim 3,
Since the switching member is formed with a fitting groove into which the engaging piece of the lock member is fitted in the case of the second operation mode, when the inner lifter is in the phase in contact with the rear side of the base circle of the inner cam, Then, the control rod enters the cam groove, the engaging piece of the lock member fits into the fitting groove of the switching member, and prevents the switching member from retreating. Therefore, cam switching, that is, lift characteristics (cam)
Is not performed, and the incomplete switching member transition phenomenon as described above does not occur.

When a switching command is issued in another phase of the cam, the inner lifter is similarly in contact with the front of the base circle, that is, the switching member is at the groove position of the inner lifter, and The switching operation is started from a state in which a load causing a displacement between the motor and the outer lifter does not act for a while, and the switching member is completely shifted.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 As shown in FIG. 1, a variable valve lift device 10 of this embodiment opens and closes a port 52 by moving up and down in the direction of an axis C and is urged in a closing direction by a valve spring 60. The exhaust valve 24, the inner cam 22 disposed on the axis C of the intake / exhaust valve 24, and the nose NO (FIG. 5B) that is juxtaposed to the inner cam 22 and is larger than the nose NI (FIG. 5B) of the inner cam 22. outer cam 20 having b))
(The base circle BI of the inner cam 22 and the outer cam 20
Is the same as the base circle BO in this example) and the outer cam 2
The outer lifter 26 urged by the springs 46 and 61 in the direction in which the inner lifter 26 contacts the upper and lower surfaces of the intake and exhaust valves 24 and has an annular groove 62 formed in the outer periphery.
When the outer lifter 26 slides in the direction perpendicular to the axis C of the intake / exhaust valve 24 and moves together with the outer lifter 26 and comes into contact with the base circle BO of the outer cam 20, the outer lifter 26 is positioned at the annular groove 62 of the inner lifter 28. It has a switching plate 70 arranged and control means (not shown) for moving the switching plate 70 in a direction perpendicular to the axis of the intake / exhaust valve 24.

The control means causes the switching plate 70 to enter the annular groove 62 to engage the inner lifter 28 and the outer lifter 26 to open and close the intake / exhaust valve 24 in a high lift state. , The switching plate 70 is retracted from the annular groove 62 so that the inner lifter 2
The mode is switched to a low-lift mode in which the outer lifter 8 is engaged with the outer lifter 26 to open and close in a so-called low-lift state.

Further, as shown in FIG.
A cam groove 11 is formed on the rear side of the second base circle BI,
On the other hand, as shown in FIG. 3 and FIG. 4, the control rod 12 urged upward by the insertion spring 13 so that the shaft center can be moved in the axial direction within a predetermined range. Is provided. The control rod 12 is provided with an upper end 121 that protrudes to the position of the cam groove 11 of the inner cam 22 and abuts on the base circle BI of the inner cam 22, and moves up and down the outer peripheral side of the annular groove 62 of the inner lifter 28. The lock member 14 that regulates the movement of the switching plate 70 into the annular groove 62 is provided. Lock member 14
Moves up and down along the outer peripheral surface of the annular groove 62 of the inner lifter 28 in response to the vertical movement of the control rod 12, thereby protruding to the side of the annular groove 62 of the inner lifter or sinking below the side. Are provided.

The following is a supplementary explanation for each. The state shown in FIG. 1 shows the pair of outer cams 20 for the high lift characteristic (curve 892 in FIG. 12) and the low lift characteristic (FIG.
The inner cam 22 of the two curves 891) is in a state where the lift amount is zero. That is, the outer cam 20 and the inner cam 22 are in contact with the outer lifter 26 and the inner lifter 28 at the center of the respective base circles BO and BI, and the intake / exhaust valve 24 closes the port 52. . The cams 20, 22 are fixed to a camshaft 39 to which a driving force from the engine is transmitted. The base circle BO of the outer cam 20 is the inner cam 2
2 is set larger than the base circle BI.

As shown in FIGS. 4 and 5, the outer lifter 26 has a disc-shaped end 261 and a cylindrical side wall 262, and a through hole 261 formed in the disc-shaped end 261.
a, a stepped inner lifter 28 having a small-diameter portion and a large-diameter portion is rotatable around the axis C of the intake / exhaust valve 24 at the large-diameter portion and in the direction of the axis C of the intake / exhaust valve 24. Is slidably fitted in The inner lifter 28 is disposed so as to always contact the upper end of the stem 56 of the intake / exhaust valve 24 via a shim 58 and a cylindrical retainer 581 having a flange.

The cylindrical side wall 262 of the outer lifter 26 is slidably inserted into a guide hole 32 formed in the cylinder head 30 in the direction of the axis C of the intake / exhaust valve 24. It is fitted so as to be rotatable about C.
Further, inside the outer lifter 26, an inner body 36 having a through hole 36a into which the small diameter portion of the inner lifter 28 is slidably fitted is arranged so as to be integrally movable with the outer lifter 26 and not to rotate relatively. ing. A spring 46 is provided between the retainer 581 and the inner body 36, and a spring 61 is provided between the bottom of the guide hole 32 and the inner body.
Is provided, and pushes the inner body 36 (outer lifter 26) upward.

The urging force of the spring 46 is set smaller than the urging force of the spring 13. A body hole 54 having a center perpendicular to the axis of the intake / exhaust valve 24 is formed in the inner body 36. The annular groove 62 is formed between the small-diameter portion and the large-diameter portion of the inner lifter 28, opens in the radial direction of the inner lifter 28, and when the lift amount shown in FIG.
4 (the same position in the direction of the axis C).
A switching plate 70 having substantially the same width as the opening width of the annular groove 62 of the inner lifter 28, that is, the width in the direction of the axis C of the body hole 54 is slidably accommodated in the bore hole 54.

As shown in FIGS. 6 and 7, a through hole 342 having substantially the same size as the outer diameter of the inner lifter 28 is formed in the switching plate 70. Switching plate 70
The first state (the retreat position, FIGS. 4 and 6) in which the axis of the through hole 342 coincides with the axis of the annular groove 62 of the inner lifter 28, and the second state (the forward position) in which the axes do not coincide with each other. ,
5 and 7). And FIG.
In the retracted position of the switching plate 70 shown in FIG. 6, the inner lifter 28 is relatively movable in the through hole of the outer lifter 26 and the through hole of the inner body.

The switching plate 70 shown in FIGS.
In the forward position, the switching plate 70 enters the annular groove 62, the outer lifter 28 and the inner lifter 26 are engaged via the switching plate 70, and the lifters 28, 26 move integrally. The front end of the switching plate 70 is provided with a spring 88 between the front end 701 (FIGS. 6 and 7) and the side wall of the outer lifter 26 in the large-diameter hole 54a formed at one end of the body hole 54. The switching plate 70 is normally set in the first state (retracted position).

At the other end of the body hole 54, a hydraulic chamber 72 is formed between the switching plate 70 and the outer lifter 26, and hydraulic pressure is supplied from the hydraulic pump 76 shown in FIG. Supplied via Reference numeral 74 in FIG. 1 denotes an oil pan. In a state where the hydraulic pressure is not supplied, the first force is generated by the urging force of the spring 88 as described above.
The state (retreat position, FIG. 4) is maintained. The hydraulic passage 84 formed in the outer lifter 28 has one end opened to the pressure chamber 72 and the other end opened to an annular groove formed on the inner peripheral surface of the guide hole 32. The hydraulic passage 80 is formed in the cylinder head 30 and is opened in an annular groove.

In the first state (retracted position) of the switching plate 70, the intake / exhaust valve 24 is driven by the inner cam 22 and the inner lifter 28, and the curve 8 in FIG.
A low lift characteristic indicated by 91 is realized. On the other hand, in the second state (forward position) of the switching plate 70 in which the inner lifter 28 and the outer lifter 26 are engaged, the switching plate 70 is driven by the outer cam 20 having a large cam trajectory and capable of realizing high lift characteristics. The intake / exhaust valve 24 is driven from the outer lifter 26 abutting on the cam 20 via the inner lifter 28 to realize the high lift characteristics shown by the curve 892 in FIG. The control means cuts off the oil pressure in accordance with the operating state of the engine to realize the first state (retracted position) or supplies the oil pressure to reduce the oil pressure to the second state (forwarded position). Manipulate.

Further, in the variable valve lift device 1 of the present embodiment, as shown in FIGS.
The cam groove 11 is provided on the rear side of the base circle BI (the side that comes into contact with the inner lifter 28 with a delay). As shown in FIGS. 4 and 5, the inner lifter 28 is formed with a stepped through hole 28a extending in the axial direction at the axial position. The control rod 12 has a stepped shape that is slidably fitted in the through hole 28a in the axial direction by a predetermined amount, and the outer peripheral step is in contact with the step of the through hole 28a (see FIG. 4).
The upper step 121 on the small diameter side protrudes from the end 261 and is located in the cam groove 11 of the inner cam 22.
In the small diameter portion of the inner lifter 28, a hole 28b orthogonal to the large diameter portion of the through hole is formed. In the hole 28b, a pin 142 constituting the lock member 14 with the above-mentioned locking piece 141 is provided. It is fitted movably in the axial direction of the through hole 28a. The hole 28b may have an elliptical cross section extending in the axial direction of the through hole 28a.

In the large diameter portion of the through hole 28a, a pin 142 is provided.
The spring 13 is provided between the spring 13 and the retainer 581. As a result, the upper end 121 of the control rod 12 is moved to the inner cam 22 by the spring 13 via the pin 142.
The inner lifter 28 is always urged toward the side (upward in FIG. 4) that contacts the base circle of the inner cam 22.
The upper end 12 of the control rod 12
Only when 1 is at the position of the cam groove 11, the upper end 121 protrudes from the end 261 by the spring 13 as described above.

At both ends of the pin 142, locking pieces 141 are fixed integrally with the pin 142 so as to be movable in the axial direction of the through hole 28a. The locking piece 141 has a cylindrical shape along the outer peripheral surface of the small diameter portion of the inner lifter 28. When the control rod 12 moves upward by the spring 13 and the upper end 121 is projected, as described above. , Locking piece 14
The upper end of 1 is projected into the annular groove 62.

As a result, when the inner lifter 28 faces the rear side of the base circle BI of the inner cam 22 and the upper end of the control rod 12 is located at the position of the cam groove 11 of the inner cam 22, that is, as described above. In the cam phase in which the switching failure is likely to occur, the direction of the cam groove 11, ie, the base circle B
The upper end of the control rod 12 rises toward the inside of I. Then, the engagement piece 141 constituting the lock member 14 rises along the outer peripheral surface of the annular groove 62 in conjunction with the control rod 12, thereby suppressing the movement of the switching plate 70 as described later in detail.

For example, in the first operation mode, that is, when the switching plate 70 does not enter the annular groove 62 of the inner lifter 28 and the inner lifter 28 and the outer lifter 26 are not engaged as shown in FIG. In this case, the raised engaging piece 141 prevents the switching plate 70 from entering the annular groove 62.

This will be described more specifically with reference to the drawings. In the variable valve lift device 1 according to the present embodiment, when the inner lifter 28 is in a phase in contact with the rear side of the base circle BI of the inner cam 22, FIG. As shown in the figure, the upper portion of the control rod 11 enters the cam groove 11 and the engagement piece 141 is inserted into the annular groove 62.
Protruding to the side. As a result, for example, the first operation mode, that is, the switching plate 70
2, the inner lifter 28 and the outer lifter 26 are not engaged.
The engagement piece 141 abuts on the front end of the rear portion 701 that enters the annular groove 62 at the point, and prevents the switching plate 70 from entering the annular groove 62.

On the other hand, when a switching command is issued in a phase other than the above, that is, in a phase in which the inner lifter 28 does not face the rear side of the base circle BI, the inner lifter 22 contacts the front of the base circle BI. The switching operation is started in a state, that is, when the switching plate 70 reaches a position facing the annular groove 62 of the inner lifter 28. When the movement of the lifter before the inner lifter 28 contacts the center of the base circle BI is stopped or at least the movement is slow, the switching plate 70 is moved, and the switching plate 70 is completely moved into the annular groove 62. I do.

As described above, when the inner lifter 28 is in contact with (or is opposed to) the rear side of the base circle BI of the inner cam 22, that is, in the case where the switching failure is likely to occur, the operating cam 20 or Switching of 22, that is, switching of the lift characteristic (cam) is not performed. As a result, in the present apparatus 1, halfway switching (transition) of the switching plate 70 does not occur. Since the incomplete switching phenomenon does not occur, the wear of the switching plate 70 and the like is reduced, and the durability is improved.

Embodiment 2 As shown in FIG. 11, this embodiment is another embodiment in which the structures of the lock member 15 and the switching plate 700 in Embodiment 1 are changed. That is, as shown in FIG. 9 or FIG. 10, the upper portion of the engagement piece 141 at the hydraulic chamber 72 side at the forward position (first state) of the switching plate A fitting groove 171 into which a part is fitted is provided. Other configurations are the same as those of the first embodiment.

As a result, for example, the first operation mode, that is, the switching plate 700 is
When the inner lifter 28 and the outer lifter 26 are not engaged with each other,
Is opposed to the rear side of the base circle B1 of the inner cam 22 and the upper end of the control rod 12 is located at the position of the cam groove, as shown in FIG.
The raised engagement piece 141 is connected to the annular groove 6 of the switching plate 700.
Prevent entry into 2.

In the second operation mode, that is, as shown in FIG. 10, when the switching plate 700 has entered the annular groove 62 and the inner lifter 28 and the outer lifter 26 have already been engaged, the inner lifter 28 is opposed to the rear side of the base circle B1 of the inner cam 22 and the upper end of the control rod 12 is at the position of the cam groove.
As described above, the locking piece 141 is fitted to the 71, so that the switching plate 700 is prevented from retreating from the annular groove 62.

Accordingly, the inner lifter 28 has the base circle B
In the case where the phase is opposite to the rear side of I, the switching of the operating cam 22 or 20, that is, the switching of the lift characteristic is not performed, and the incomplete transition plate 700 transition phenomenon does not occur. On the other hand, when a switching command is issued in a phase other than the above, that is, in a phase in which the inner lifter 28 does not face the rear side of the base circle BI, the switching is performed by the locking piece 141 as in the first embodiment. Since the movement of the plate 700 is not prevented, the switching is not prevented. Others are the same as the first embodiment.

[0045]

As described above, according to the present invention, it is possible to obtain a variable valve lift device which can reliably switch the lift amount and has excellent durability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a variable valve lift device according to a first embodiment (when an intake / exhaust valve is closed).

FIG. 2 is a cross-sectional view of the variable valve lift device according to the first embodiment (when an intake / exhaust valve is opened in a mode in which an inner cam operates).

FIG. 3 is a cross-sectional view of the variable valve lift device according to the first embodiment (when the intake / exhaust valve is opened in a mode in which the outer cam operates).

FIG. 4 is an enlarged view of a main part around an inner lifter in a mode in which a lock member operates and an inner cam operates, and is a front view (a) in a state where the inner lifter is located at a position facing a cam groove of the inner cam. Side view (b).

FIG. 5 is an enlarged view of a main portion around the inner lifter in a mode in which the lock member does not work and the inner cam operates, and is a front view (a) and a side view in a state where the inner lifter is located at a position facing the nose of the inner cam; Figure (b).

FIG. 6 is a sectional view taken along line AA in FIG. 4;

FIG. 7 is a sectional view taken along line BB in FIG. 3;

FIG. 8 is a front view of the inner cam according to the first embodiment.

FIG. 9 is an enlarged view of a main part around an inner lifter in a state where a lock member is operated in a first operation mode in the variable valve lift device according to the second embodiment (front view (a));
And a side view (b).

FIG. 10 is an enlarged view (a front view (a) and a side view (b)) of a main part around an inner lifter in a state in which a lock member in a second operation mode is operable in the variable valve lift device according to the second embodiment. ).

FIG. 11 is a cross-sectional view of the variable valve lift device according to the first embodiment (when the intake / exhaust valve is open).

FIG. 12 is a diagram showing a relationship between a lift amount of an intake / exhaust valve and a rotation angle of a cam at a low lift characteristic and a high lift characteristic in the conventional device and the first and second embodiments.

FIG. 13 is a cross-sectional view of a conventional variable valve lift device (when the intake / exhaust valve is closed).

[Explanation of symbols]

 11. . . 11. cam groove, . . Control rod, 14. . . Lock member, 20. . . Outer cam, 22. . . Inner cam, 24. . . Intake and exhaust valves, 26. . . Outer lifter, 28. . . Inner lifter, 62. . . 70. Groove (of inner lifter) . . Switching member,

Claims (3)

[Claims] An intake / exhaust valve which opens and closes a port by being moved up and down in an axial direction and is urged in a closing direction; an inner cam disposed on an axis of the intake / exhaust valve; An outer cam having a base circle and a nose larger than a base circle and a nose of the inner cam, an outer lifter urged in a direction to contact the outer cam, and an outer periphery in contact with an upper end surface of the intake and exhaust valve. And a position of the inner lifter groove when the outer lifter slides in a direction perpendicular to the axis of the intake / exhaust valve, moves together with the outer lifter, and contacts the base circle of the outer cam. And a control means for moving the switching member in a direction perpendicular to the axis of the intake / exhaust valve, and moving the switching member into the groove. A high lift mode in which the inner lifter is engaged with the inner lifter to open and close the intake / exhaust valve in a high lift state, and a low lift mode in which the switching member is retracted from the groove to engage the inner lifter with the outer lifter. In a variable valve lift device configured to be switchable to a low lift mode in which it can be opened and closed in a state, a cam groove is formed on a rear side of a base circle of the inner cam, while a shaft center portion is formed on the inner lifter. A control rod which is inserted and urged upward so as to be movable in a predetermined range in the axial direction is provided, and the control rod protrudes to a position of a cam groove of the inner cam and a base of the inner cam. It has an upper end that comes into contact with a circle, and moves up and down the outer peripheral side of the groove of the inner lifter in response to the vertical movement of the control rod, thereby restricting the movement of the switching member into the groove. Variable valve lift device, characterized in that the locking member is provided such. 2. The lock member according to claim 1, wherein
An engagement piece that moves up and down along the outer peripheral surface of the groove of the inner lifter, thereby protruding to the side of the groove of the inner lifter or sinking below the side to restrict or permit movement of the switching member. A variable valve lift device comprising: 3. The variable valve lift device according to claim 2, wherein the switching member is provided with a fitting groove into which the engaging piece is fitted when the switching member moves to the groove. .