JP3330635B2 - Variable engine valve timing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing device for an engine that changes the opening and closing timing of intake and exhaust valves.

[0002]

2. Description of the Related Art In general, suction in an automobile engine,
Since it is preferable that the opening / closing timing of the exhaust valve be changed according to the operating state of the engine, various valve timing variable devices have been conventionally proposed.

[0003] For example, Japanese Patent Application Laid-Open No.
Japanese Patent No. 88014 discloses a tappet having a pressure receiving portion for receiving a force from a cam surface of a camshaft and a pressing portion for transmitting a force from the cam surface to a valve stem, and a fitting for slidably fitting the tappet. An engine valve timing control device is disclosed which includes a rotating member having a hole and rotatably supported around a camshaft, and an operating device for rotating the rotating member according to an operating state of the engine. I have.

In this device, the rotating member is held at a reference position where the sliding direction of the tappet and the moving direction of the valve coincide with each other at least when the engine is under a high load and a high speed, so that the tappet and the valve stem are separated. No slippage occurs between the tappet and the valve stem at the time of low-speed rotation, so that the rotation member is rotated from the reference position, thereby causing a slip between the tappet and the valve stem. , So that the valve timing can be changed.

In the variable valve timing apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 3-115714, a low-speed cam and a high-speed cam are provided side by side on a camshaft, and both the low-speed cam and the valve are engaged. The main rocker arm and the auxiliary rocker arm that engages only with the high-speed cam are provided adjacent to each other so as to be swingable on the rocker shaft, and can move in the axial direction of the rocker shaft by hydraulic pressure. A switching mechanism is provided which can selectively switch the main and sub rocker arms to an interlocking state or a non-interlocking state by engaging and disengaging a pin. When the engine is running at high speed, the main and sub rocker arms are connected by the pins. The valve is driven by the high-speed cam, and the main and
The sub rocker arm is set in a non-interlocked state, and the valve is driven by the low speed cam.

[0006]

By the way, in the former, that is, in the structure disclosed in Japanese Patent Application Laid-Open No. 59-188014, when the engine with a high valve operating speed rotates at high speed, a slip occurs between the tappet and the valve stem. The wear of the valve stem and tappet is reduced, and when the engine is running at a low speed, even if the tappet and the valve stem are slipped, the wear of the valve stem and tappet is also reduced due to the low valve operating speed. It has an excellent effect.

However, in this configuration, only the valve timing can be delayed by the slip between the tappet and the valve stem. For example, the advance of the valve opening timing and the delay of the valve closing timing are simultaneously performed. Since it is theoretically impossible to extend the valve opening angle, it has been difficult to increase the maximum output in a high-load and high-speed range.

On the other hand, the latter, that is, the structure disclosed in Japanese Patent Application Laid-Open No. HEI 3-115714, makes it possible to independently select valve lift characteristics suitable for the low rotation range and the high rotation range of the engine. Although it is possible to improve the performance of, the number of parts increases and not only requires a special camshaft and complicated oil passage, but also the main and sub rocker arms can be switched between the interlocked state and the non-interlocked state. There is a possibility that an impact may occur when switching, and there is a problem in durability of the pin because a shearing stress acts on the pin for disengagement.

In view of the above problems, the present invention provides a variable valve timing device for an engine that can simultaneously advance the valve opening timing and retard the valve closing timing without impact. The purpose is to do.

[0010]

Means for Solving the Problems The present invention variable valve timing device for an engine according to the the crankshaft
A camshaft that is rotationally driven and has an external gear;
It has an internal gear that meshes with the external gear of the camshaft.
The cam rotation axis decentered from the camshaft axis
A valve drive that rotates as a center to open and close the valve
And an eccentric cam, arranged parallel to the camshaft
Eccentric camshaft driven by the camshaft
Shaft and the eccentric cam in conjunction with the eccentric rotational movement of the eccentric cam.
By swinging around the shaft, the valve drive cam
A rocking member for changing the rotation phase,
Change the rotation phase of the eccentric camshaft with respect to the rotation phase.
Phase changing means for changing the valve driving cam.
The phase of the opening and closing operation of the valve by the rotation phase of the camshaft
To the advance and retard angles
ing.

According to one aspect of the invention, a camshaft is provided.
And a valve drive cam provided on the camshaft.
Opening and closing operation of the valve by the rotation of the valve drive cam
And an eccentric cam.
Driven by the camshaft arranged parallel to the shaft
Eccentric cam shaft and the eccentric rotational movement of the eccentric cam
A swing member that swings by the movement, and swing of the swing member.
A link member reciprocating by a dynamic motion, and the valve
While the rocker arm is in contact with the cam surface of the drive cam,
The link member is rotatably supported by the
Reciprocating within a specified range along the cam surface of the valve drive cam
Moving cam follower and the rotation phase of the camshaft
On the other hand, the position for changing the rotation phase of the eccentric camshaft
A phase change means, and the valve is driven by the valve driving cam.
Of the camshaft rotation phase
The angle side and the retard side are configured to be changed.

[0012]

According to the operation and effect of the present invention, by the phase with respect to the cam shaft of the opening and closing operation of the valves is set so as proceeds during opening of the valve, and late during closing of the valve, during the opening of the valve Can be performed simultaneously with the retard angle when the valve is closed. Further, there is no possibility that a shock is caused when the phase is changed, and a highly reliable valve timing variable device can be easily obtained. Also change phase
Means for rotating the camshaft with respect to the rotational phase of the camshaft.
To change the shaft rotation phase, open the valve.
And further retarding when the valve is closed
be able to. A valve driving cam is swingably mounted on the camshaft around the axis of the camshaft, and the valve driving cam always swings with respect to the camshaft with the swinging of the swinging member. Therefore, this swing is performed in a state where the phase of the eccentric cam is set so that the phase of the valve driving cam changes to the advance side when the valve is opened and to the retard side when the valve is closed. By continuously changing the phase of the eccentric cam with respect to the crankshaft, it is possible to continuously change the degree of change of the phase of the valve driving cam to the advance side and the retard side.

Therefore, the charging efficiency can be improved in the entire operation range without deteriorating the characteristics of the engine in the light load range at all. Further, since the valve timing variable means is provided for each cylinder, it can be applied to various multi-cylinder engines.

According to still another aspect of the present invention, a cam follower is provided between the valve driving cam and the valve,
Since the cam follower is always swung around the valve driving cam with the swing of the swing member, the same operation and effect as described above can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable valve timing device for an engine according to the present invention will be described below with reference to the drawings .

[0016] The first embodiment of the present invention will be described with reference to FIGS. 1 to 5. The present embodiment is configured such that the phase of the cam with respect to the camshaft is changed for each cylinder.

In FIG. 1 and FIG. 2 which is a sectional view taken along the line XX, an intake camshaft 32 is rotatably supported on a cylinder head 31 and a cam for driving an intake valve is provided on the camshaft 32. 33 is installed,
As is particularly clear from FIG. 3, which is a cross-sectional view taken along the line XI-XI in FIG. 2 , the cam 33 is formed in a hollow shape, and an internal gear 33a is formed on the inner peripheral surface thereof around the rotation axis O. Have been. The camshaft 32 penetrates the hollow portion of the cam 33 at a position eccentric with respect to the rotation axis O of the cam 33, and the external gear 32a formed on the outer peripheral surface of the camshaft 32 A differential gear mechanism is formed by internally meshing with the gear 33a.

FIG. 2 and its XII-
As is clear from FIG. 4 which is a cross-sectional view along the line XII,
Circular recesses 33b, 33b having a larger diameter than the internal gear 33a are formed coaxially. The cylindrical portions 34a, 34a of the intermediate member 34, which is a swinging member, are fitted into the circular concave portions 33b, 33b so as to sandwich the cam 33, and rotatably support the cam 33.

The intermediate member 34 is supported by the camshaft 32 in such a manner that the camshaft 32 is rotatably inserted.
In addition, the cam 33 is positioned so as to be rotatable around its rotation axis. Since the ratio of the number of teeth between the external gear 32a of the camshaft 32 and the internal gear 33a of the cam 33 is set to 1: 2, the camshaft 32 and the cam 33 are reduced in speed with a reduction ratio of 2. It also constitutes the mechanism. The intermediate member 34 has a bifurcated arm portion 34 which is vertically engaged with an eccentric cam 35 which swings the intermediate member 34, which will be described later.
b and 34b are integrally extended as a cam follower portion.

The eccentric cam 35 is formed integrally with a sub camshaft 36 which is rotatably supported by the cylinder head 31 in parallel with the intake valve driving camshaft 32, and is disposed adjacent to the intake valve driving cam 33. The auxiliary camshaft
When the eccentric cam 35 is rotated along with the rotation of the arm 36, the arm portion 34 engaging the eccentric cam 35 from above and below is
The intermediate member 34 provided with b and 4b swings around the camshaft 33, and the camshaft 32
33 phases are advanced or retarded.

On the other hand, as shown in FIG. 2 , a cam pulley 37 driven by a crankshaft (not shown) via a timing belt or a chain is fixedly provided at one end of the camshaft 32. In this case, as described above, since the speed is reduced between the camshaft 32 and the cam 33 with the reduction ratio being 2, the cam pulley 37 has the same diameter as the crank pulley. Further, a helical gear 38 is integrally fixed to the camshaft 32, and a helical gear 39 provided on the auxiliary camshaft 36 and having the same diameter as the helical gear 38 meshes with the helical gear 38 to rotate the camshaft 32, The rotation of the crankshaft is transmitted to the sub camshaft 36 at the same rotation speed.

The helical gear 39 on the sub camshaft 36 side
By being spline-coupled to the auxiliary camshaft 36, it can be moved in the axial direction and
40 urges the eccentric cam 35 toward the opposite side.
The sub camshaft 36 is provided on the wall 31a of the cylinder head 31 facing the helical gear 39 on the sub camshaft 36 side.
A pair of cylinder-shaped oil sumps 41, 41 that open toward the helical gear 39 on both sides of the oil sump are formed.
Inside, there are provided pistons 42, 42 whose tips are in sliding contact with side surfaces 39a of the helical gear 39. The above sump 41, 41
Oil passage 43 formed in wall portion 31a of cylinder head 31
The pistons 42, 42 move toward the helical gear 39 by the hydraulic pressure of the hydraulic oil supplied to the oil passage 43, and push the helical gear 39 against the biasing force of the spring 40, thereby causing the eccentric cam 35 to move. Move to This helical gear 39
Is moved, the phase of the sub camshaft 36 with respect to the valve driving camshaft 33, that is, the phase of the eccentric cam 35 with respect to the crankshaft is advanced.

The intake valve 43 that is driven by a cam 33 having such a configuration, as shown in FIG. 1,
1 is slidably supported by the valve guide 44, and is urged upward in FIG. 1 , that is, in the valve closing direction by a valve spring 45. A bucket-shaped lash adjuster 46 is provided between the cam 33 and the intake valve 43. It is interposed.

FIG. 5 shows the ignition order of ^# 1 → ^# 2 → ^# 3 → ^# 4 → ^#
In the V6 engine with 5 → ^# 6, ^# 1,
^This figure shows the swinging operation of the intermediate member 34 that can obtain the valve characteristics of early opening and late closing for each intake valve of the cylinders ^# 3 and ^# 5. In this case, the intake valves of cylinders ^# 1, ^# 3, and ^# 5 are respectively crank angle (CA).
With a period of 720 ° and a phase difference of 240 ° with each other at a crank angle.
When the hydraulic oil is not supplied to the oil passage 43, the eccentric cam 35 has a crank angle as shown by a solid line.
The intermediate member 34 is oscillated at a cycle of 360 °.

Next, when hydraulic oil is supplied to the oil passage 43 and the pistons 42 and 42 move the helical gear 39 of the sub camshaft 36 upward in FIG. 2 against the urging force of the spring 40, the sub camshaft The phase of 36 relative to the camshaft 32,
That phase is allowed to proceed continuously with respect to the crankshaft of the eccentric cam 35, along with this, because the phase of the swing curve of the intermediate member 34 is allowed to proceed as shown in broken lines in FIG. 5, the intake As shown by the broken line, the lift characteristic of the valve 43 is further advanced with respect to the solid line characteristic when the valve is opened, and further retarded with respect to the solid line characteristic when the valve is closed. .

As described above, in the present embodiment, the phase of the intake valve driving cam 33 with respect to the camshaft 32 is advanced to the advanced angle when the valve is opened with the swing of the intermediate member 34 which is always swinging. When the valve is closed, it always changes to the retard side, and in this state, the phase of the auxiliary camshaft 36 with respect to the camshaft 32,
That is, the phase of the eccentric cam 35 with respect to the crankshaft is advanced, whereby the degree of change of the phase of the cam 33 to the advance side and the retard side is continuously increased. Therefore, the charging efficiency can be improved in the entire operation range without deteriorating the characteristics of the engine in the light load range at all.

Furthermore the second embodiment of the present invention with reference to FIGS. 6 to 10 will be described.

In this embodiment, as apparent from the sectional view of FIG. 6 , a valve driving cam 50 is fixed to a cam shaft 51, and a roller 53 as a cam follower is provided between the cam 50 and the intake valve 52. The provided rocker arm 54 is interposed. The roller 53 is oscillated around the cam 50 by an oscillating member 56 which oscillates with the rotation of the eccentric cam 55, whereby the opening / closing operation phase of the intake valve 52 with respect to the cam 50 is changed for each cylinder. It is configured to be.

[0029] In more detail the structure of the present embodiment, in FIG. 6, the intake valve 52 is slidably supported in a valve guide 58 fixed to the cylinder head 57, and in FIG. 6 by a valve spring 59 upward, i.e., as has been urged in the closing direction, the rocker arm 54 is shown in Figure 9, the cylinder head 57
One end is supported by a lash adjuster 60 provided at the other end, and the other end is in contact with the upper end of the stem of the intake valve 52. As is apparent from FIG. 7, which is a view seen from the direction of arrow H in FIG. 6 , the rocker arm 54 has a space 54a for holding the roller 53 from both sides. The rocker arm 54 has holes for supporting both ends of the shaft 62 of the roller 53.
The holes 63, 63 are formed as arc-shaped long holes so that the roller 53 can move along the cam surface of the cam 50. Both sides of the shaft 62 of the roller 53 project from the side surface of the rocker arm 54.

The eccentric cam 55 is formed integrally with a sub camshaft 64 which is rotatably supported by a cylinder head 57 in parallel with the camshaft 51 for driving the intake valve. A shaft 65 that supports the swinging member 56 so as to be able to swing freely is substantially halfway between the camshafts 51 and 64.
It is arranged in parallel with.

As is apparent from FIG. 10 , the swinging member 56 has an engaging portion 56 which engages with the eccentric cam 55 from above and below.
a, and a pair of arms 56b, 56b extending downward from a position supported by the shaft 65.
Pins 66 are attached to the tips of 56b and 56b, respectively. The other ends of the link plates 67, 67 each having one end pivotally supported by the pins 66, 66 are engaged with the protruding ends of the shafts 62 of the rollers 53 projecting from both side surfaces of the rocker arm 54.

With such a link mechanism, the eccentric cam
The swing of the swing member 56 accompanying the rotation of the 55 is transmitted to the roller 53. Then, in this case, the roller 53 has its shaft 62
Is supported by the rocker arm 54, the roller 53 is swung around the cam 50 by using the long holes 63, 63 as a guide in response to the swing of the swing member 56.
The phase of the opening / closing operation of the intake valve 52 with respect to is changed for each cylinder. Then, the same operation as that shown in FIG. 5 is performed by using the phase changing means of the eccentric cam as shown in FIG. 2 , for example.

Therefore, also in this embodiment, similarly to the above-described first embodiment, the opening angle of the intake valve 52 can be continuously changed, and the same effect as that of the first embodiment can be obtained. Things.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a first embodiment of the present invention .

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is an enlarged sectional view taken along the line XI-XI in FIG. 2;

FIG. 4 is an enlarged sectional view taken along line XII-XII of FIG. 2;

FIG. 5 shows a device according to a first embodiment of the present invention,
Timing to explain the operation when applied to engines
chart

FIG. 6 is a sectional view showing the structure of a second embodiment of the present invention .

FIG. 7 is a plan view of the configuration of FIG. 6 viewed from the direction of arrow H;

FIG. 8 is a sectional view taken along the line XVI-XVI in FIG . 7;

FIG. 9 is an enlarged view of a main part of FIG . 6;

FIG. 10 is an enlarged sectional view of a main part of FIG. 6;

[Explanation of symbols]

 31, 57 Cylinder head 32, 51 Cam shaft 33, 50 Cam 5 Variable valve timing device 37 Cam pulley 35, 55 Eccentric cam 34 Intermediate member 36, 64 Secondary cam shaft 53 Roller 54 Rocker arm 56 Swing member 67 Link plate

Claims (2)

(57) [Claims] 1. A rotary drive by a crankshaft,
A camshaft having an external gear; and an internal gear meshing with the external gear of the camshaft.
And a cam rotating shaft eccentric from the axis of the camshaft.
Valve that rotates around the heart and opens and closes the valve
It has a drive cam and an eccentric cam, and is arranged in parallel with the camshaft.
Eccentric camshaft driven by the camshaft
And the camshaft is linked to the eccentric rotation of the eccentric cam.
By swinging around the shaft, the rotation phase of the valve drive cam
An eccentric camshaft with respect to a rotational phase of the camshaft.
Phase changing means for changing the rotational phase of the shaft, and the phase of the valve opening / closing operation by the valve driving cam is changed.
Change to advance and retard sides of the rotation phase of the engine shaft
An engine characterized by being configured to cause
Variable valve timing device. 2. A camshaft, a valve driving cam provided on the camshaft, and opening and closing of a valve by rotation of the valve driving cam.
Having a rocker arm and an eccentric cam, which are arranged in parallel with the camshaft.
Eccentric camshaft driven by the camshaft
When the swing of swinging motion by eccentric rotation of the eccentric cam
Member and a link portion that reciprocates by the swinging motion of the swinging member
Material and the lock surface while contacting the cam surface of the valve drive cam.
The link arm is rotatably supported by the car arm,
A predetermined range along the cam surface of the valve drive cam by the reverse movement
A cam follower reciprocating in the inside, and the eccentric camshaft with respect to the rotational phase of the camshaft.
And a phase changing means for the shift of the rotational phase varying calico, mosquito phase of the opening and closing operation of the valve by the valve drive cam
Change to advance and retard sides of the rotation phase of the engine shaft
An engine characterized by being configured to cause
Variable valve timing device.