JPH0512523B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve operating system for an engine that can change the lift amount and valve opening period of intake and exhaust valves depending on the operating state.

[Conventional technology]

When setting the operating characteristics of the engine's intake and exhaust pulp, the valve lift is used to improve combustion stability and fuel efficiency by suppressing exhaust blowback and intake air blow-through during the valve overlap period at low speeds. It is desirable that the valve lift amount and valve opening period be relatively small, and at high speeds, it is desirable to increase the valve lift amount and valve opening period in order to improve output and the like.

In order to satisfy these demands, we have developed a system in which multiple cams with different cam nose shapes are provided, a valve is selectively linked to one of these cams, and the linkage is switched depending on the operating condition. Valve devices are also known in the prior art.

For example, in Japanese Utility Model Application Publication No. 57-182205, one valve has two cams of a low-speed type and a high-speed type and one rocker arm, and the cam side portion of the rocker arm is formed into a bifurcated shape. One end of the member is used as a contact part for the low-speed cam, and the other end is equipped with a slidable high-speed cam contact member and a stopper that prevents the sliding. A device is disclosed that is operated by an actuator such as a cylinder via an interlocking mechanism.
In this device, by controlling the actuator according to the operating state, the high-speed cam abutting member moves freely at low speeds, and the operation of the high-speed cam is not transmitted to the valve, so that the low-speed cam operates the valve. At high speeds, the high speed cam abutting member is prevented from sliding so that the operation of the high speed cam is transmitted to the valve.

Furthermore, in Japanese Patent Application Laid-Open No. 57-110708, two cam-side arms (valve levers) that abut on cams of different shapes and a valve-side arm (connection element) that abuts on a valve are separately formed. The arms are rotatably supported by the rocker shaft, and the valve side arm is movable in the axial direction of the rocker shaft, and a meshing part is provided on the corresponding surface of the valve side arm and each cam side arm, so that the valve side arm can be moved in the axial direction. A device is disclosed in which the valve-side arm is selectively engaged with and connected to one of the cam-side arms by moving the valve-side arm to one of the cam-side arms.

Further, in U.S. Patent No. 4,151,817, a low lift cam and a high lift cam are disposed on a camshaft, and a rocker arm is integrally provided with a contact part for the low lift cam (first cam follower) and a contact part for the valve. a first arm (link) supported by a spherical fulcrum, and a second arm (first cam follower) having an abutting portion for the high lift cam and having one end pivotally supported by the first arm. ,
A latch for locking the second arm is rotatably attached to the first arm via a pivot, and is connected to the latch via a rod to a fixed frame outside the valve mechanism. A device is disclosed that includes a lever and an electromagnetic actuator for actuating the lever. In this device, a latch attached to the first arm is rotated by an actuator installed outside the valve mechanism via a lever and a rod, so that the latch is attached to the second arm with respect to the first arm. The second arm can be switched between a connected state in which the second arm is locked and a non-connected state in which the second arm is unlocked.

[Problem to be solved by the invention]

However, each of the above conventional devices has the following problems.

That is, according to the device disclosed in Japanese Utility Model Application Publication No. 57-182205, a slidable member is provided in the part of the rocker arm that comes into contact with the high-speed cam.
A sliding gap is created between this member and the end of the rocker arm, and the direction of the force applied to this member from the cam changes as the cam rotates, so this member tends to wobble during operation. Such looseness generates noise and tends to cause wear, reducing reliability. In addition, this member and the stopper are installed at the end of the rocker arm located far from the rocker shaft, and
Since the actuator and interlocking mechanism are also installed on the Rocker arm, the structure becomes more complex, and the moment of inertia of the Rocker arm increases, making it easier for so-called valve jumping to occur during high-speed rotation, which lowers the engine speed limit. There is also the problem of doing so.

According to the device disclosed in Japanese Patent Application Laid-Open No. 57-110708, when the valve side arm moves in the axial direction of the rocker shaft, the point of action of this arm on the valve stem shifts, causing an unbalanced force to act on the valve. This poses problems such as the smooth operation of the valve is likely to be hindered.

Also, according to the device shown in U.S. Pat. No. 4,151,817, a latch is attached via a pivot to a first arm of the rocker arm, while a lever and an actuator for rotating the latch via the rod are located outside the valve mechanism. It is attached to a fixed frame, and when the first arm slides, the axis of the latch moves relative to the axis of the lever, so the arrangement and distance of these members must be set strictly. For example, when the second arm is connected to the first arm, if the first arm slides, the latch may rotate and separate from the second arm. There are problems such as difficulty in controlling dimensions.

In view of these circumstances, the present invention has a simple structure that allows the valve lift amount and valve opening period to be changed by switching the linkage between cams of different shapes and valves, and moreover, does not cause rattling during operation. It prevents noise and improves reliability, reduces the moment of inertia of the Rocker arm and increases the rotational speed limit, and allows smooth valve operation.In addition, it allows difficult dimensional control. The present invention provides a valve train for an engine that does not require the use of a valve train and is advantageous in terms of manufacturing.

[Means to solve the problem]

The present invention provides a plurality of cams each having a cam nose portion with different shapes, and a valve is selectively linked to one of the cams, and the linkage is switched depending on the operating state. In an engine valve train that changes at least one of the valve lift amount or the valve opening period, the Rocker arm that contacts the plurality of cams and the valve is replaced by the arm that contacts some of the cams and the valve. The arm is divided into an arm having a contact portion, and both arms are supported so as to be able to move relative to each other around the rocker shaft while being maintained at a constant position in the axial direction of the rocker shaft. , a selector having a plunger that can freely extend and retract in the direction of the other arm is incorporated, and an actuator that operates the selector in a plunger protruding state is incorporated into a valve operating swing mechanism consisting of a rocker arm and a rocker shaft, and the selector and actuator: A switching device is configured to switch between a non-connected state in which relative movement of both arms is permitted, and a connected state in which the plunger protrudes and engages with the other arm to prevent relative movement of both arms. .

[Effect]

According to this configuration, when the two arms are brought into a connected state by the selector, the two arms swing integrally with the rotation of some of the cams. When the operation is transmitted to the valve and both arms are disconnected,
By swinging both arms independently of each other,
The operation of some of the cams is not transmitted to the valve, and the valve is operated by other cams.

〔Example〕

1A to 1E schematically show several embodiments of the device according to the invention. In the embodiment shown in FIG. 1A, two cams 3, 4 of a high speed type and a low speed type and a rocker arm 6 are provided for one intake valve (or exhaust valve) 2, and the rocker arm 6 is provided with: a first arm 7 that comes into contact with the high-speed cam 3;
It is divided into a second arm 8, which has a contact part for the intake valve 2 at one end and an integral contact part for the low-speed cam 4 at the other end.
However, it is supported so as to be able to move relative to the rocker shaft 9 while being kept in a constant position without moving in the axial direction of the rocker shaft 9. A selector 10, which can be switched between a connected state that prevents relative movement of both arms 7 and 8 and a non-connected state that allows relative movement of both arms 7 and 8, is built into either arm 7 or 8. The selector 10 is operated by the operating means according to the operating state. In the embodiment shown in FIG. 1B, each cylinder includes a plurality of (for example, two) intake valves 2a,
As applied to engines provided with 2b,
The second arm 8 of the divided rocker arm 6 is provided with abutting portions 8a and 8b for the plurality of intake valves 2a and 2b, and the rest of the structure is the same as that shown in FIG. 1A. In the embodiment shown in FIG. 1C, the second arm 8 of the Rocker arm 6, which is divided into a first arm 7 and a second arm 8, is further connected to a valve-side arm 81 that abuts the intake valves 2a and 2b and a low-speed cam 4. These arms 7 and 82, which are divided into abutting cam-side arms 82, are capable of relative movement around the rocker shaft 9, and the corresponding portions of the first arm 7 and the valve-side arm 81 and the valve-side arm 81 are Selectors 10 and 10' are provided at portions corresponding to the cam-side arm 82, respectively, so that when the selector 10 is in the connected state, the selector 10' is in the non-contact state.
Each of the embodiments shown in FIGS. 1D and 1E will be described in detail later using specific examples, but as shown in these figures
For each intake valve 2a, 2b per cylinder, two high-speed cams 3a, 3b and one low-speed cam 4, or one high-speed cam 3 and two low-speed cams 4.
Three or more cams are arranged by combining cams a, 4b, etc., and the rocker arm 6 is divided accordingly, and the selector 10 or the selector 10a,
10b may be used to switch the association.

2 to 5 show the specific structure of the embodiment shown in FIG. 1D. In these figures, cylinder 1 of the engine has two intake valves 2a and 2b and an exhaust valve (the exhaust valve and its drive system are not shown).
A camshaft 5 is provided with three cams for the intake valves 2a, 2b, consisting of high-speed cams 3a, 3b of the same shape on both sides and a low-speed cam 4 in the center. High speed cam 3 above
a, 3b and the low-speed cam 4 each have a cam nose portion for opening the intake valves 2a, 2b, and the shapes of the cam nose portions are different from each other, and are larger than the cam nose portion of the low-speed cam 4. The cam nose portions of the high-speed cams 3a, 3b are formed large. The high-speed cams 3a, 3b and the low-speed cam 4 may be cams that differ in at least one of the valve lift amount and the valve opening period, and therefore have different cam nose heights and formation ranges ( (including similar shapes), or may be different from either one of these.

A rocker arm 6 disposed between these cams 3a, 3b, 4 and the cylinder 1 is connected to both high-speed cams 3.
A pair of left and right arm portions 7a, 7 that come into contact with a, 3b
b is integrally connected to the first arm 7 via the upper connecting portion 7c, the abutting portions 8a, 8b to both the intake valves 2a, 2b, and the abutting portion 8c to the low-speed cam 4 are integrated. The second arm 8 is divided into a second arm 8 having both arm parts 7 of the first arm 7.
It is arranged between a and 7b. Both arms 7 and 8 are supported around a rocker shaft 9 so as to be movable relative to each other.

One of the arms 7 and 8 has a plunger 1 that can freely move in and out in the direction of the other arm.
In this embodiment, the selector 10 having a plunger 11 and a lever member 12 is installed in the first arm 7. Further, an actuator 20 for operating the selector 10 into a plunger protruding state is incorporated into a valve operating swing mechanism consisting of a rocker arm 6 and a rocker shaft 9. The selector 10 and the actuator 20 constitute a switching device that switches between a connected state in which the arms 7 and 8 are allowed to move relative to each other and a disconnected state in which the arms 7 and 8 are prevented from moving relative to each other. Selector 1 above
Specifically, the actuator 20 and the actuator 20 have the following structure.

A guide hole 13 is formed in the first arm 7 and the upper part thereof, and the guide hole 13 opens toward the upper part of the second arm 8.
The plunger 11 is movably housed in the guide hole 13.
The plunger 11 is biased by a spring 14 in the plunger 3 so as to come into contact with the second arm 8, and a small-diameter engaging portion 15 is formed in the middle of the plunger 11.
Further, the lever member 12 is supported on the upper part of the first arm 7 so as to be movable in the axial direction of the rocker shaft 9 perpendicular to the plunger 11. A locking hole 17 is formed which is connected to the plunger insertion hole 16 and has a size corresponding to the plunger insertion hole 16 and the engagement portion 15 . thus,
The locking hole 17 of the lever member 12 is connected to the plunger 1.
When the lever member 12 moves to the lock position where it engages with the engaging portion 15 of the arm 1, sliding of the plunger 11 is prevented, thereby preventing relative movement in the direction in which the upper parts of the arms 7 and 8 approach each other. (this time is the connected state), and on the other hand, when the lever member 12 moves to the unlocked position where the locking hole 17 is disengaged from the engaging portion 15 and the plunger 11 is inserted into the plunger insertion hole 16, the plunger By allowing sliding of arm 11, relative movement of both arms 7 and 8 is allowed (this time is a non-connected state).

The end of the lever member 12 projects outside the first arm 7 and is connected via an arm 12a to an annular hydraulic actuator 20 provided around the rocker shaft 9. When oil is supplied to the chamber 21 from an oil pump (not shown) through the oil passage 22, the lever member 12 is moved toward the above-mentioned lock position, and when oil is relieved from the hydraulic chamber 21, the lever member 12 is moved by the return spring 23. The member 12 is moved toward the unlocked position. The supply and discharge of oil to and from the hydraulic chamber 21 are controlled via the control valve 26 in the oil passage 22 by a control circuit 25 that receives the rotational speed signal 24, etc. At higher speeds, the lever member 12 is operated to the lock position, and at lower speeds, below a predetermined number of revolutions, the lever member 12 is operated to the unlocked position. The actuator for actuating the lever member 12 is not limited to the above-mentioned hydraulic type, but a solenoid or the like may be used, and the control of the actuator according to the operating state is performed according to the engine speed and load. Good too.

In addition, 27 is an adjuster provided at one end of the second arm 8 facing the intake valve 2, and 28 is an adjuster provided on the second arm 8.
An adjuster is provided at the upper part of the arm 8 to face the plunger 11, and the valve clearance is adjusted by these adjusters. Also, 29
is the cylinder head.

According to this valve train, when the engine is running at high speed, the lever member 12 is operated to the lock position to prevent the plunger 11 from sliding, so that the first arm 7 is pushed by the cam noses of the high-speed cams 3a and 3b. When the second arm 8 swings away from the low-speed cam 4 and swings together with the first arm 7, the intake valves 2a and 2b are operated in accordance with the rotation of the high-speed cams 3a and 3b. Ru. On the other hand, at low speeds, the lever member 12 is in the unlocked position and the plunger 11 is allowed to slide, so that the plunger 11 absorbs the swinging of the first arm 7 caused by the rotation of the high-speed cams 3a and 3b. is not transmitted to the second arm 8, and the swinging of the second arm 8 according to the rotation of the low-speed cam 4 causes the intake valves 2a, 2b to
is activated. In this way, the valve lift characteristics can be changed to suit the operating conditions.

In particular, a selector 10 for switching the linkage between the high-speed cams 3a, 3b and the low-speed cam 4 and the intake valves 2a, 2b is connected to both the arms 7, 8.
The device switches between a connected state and a non-connected state, and does not come into contact with a cam like the conventional device shown in the above-mentioned Japanese Utility Model Publication No. 57-182205, so the plunger 11 of this selector 10 A force always acts in a constant direction (tangential direction of the rocker shaft 9), and the plunger 11 does not wobble even during the operation of the rocker arm 6. Furthermore, since the plunger 11 need only be placed around the rocker shaft 9, the distance between the plunger 11 and the rocker shaft 9 can be made smaller than when the selector mechanism is provided at the end on the cam side as in the conventional device. Furthermore, if the actuator 20 is provided outside the rocker arm 6, the overall weight of the rocker arm 6 can be reduced. Therefore, the moment of inertia of the rocker arm 6 is reduced, and so-called valve jumping (a phenomenon in which the rocker arm and valve float off the cam due to inertia during operation) can be prevented even during high-speed rotation. Also, as in this embodiment, three cams 3a, 3b, 4
At high speeds, two high-speed cams 3a, 3b on both sides operate the intake valves 2a, 2b.
At low speeds, the central low-speed cam 4 controls the intake valve 2.
By activating the actuators a and 2b, a well-balanced force acts on the rocker arm 6 both at high speed and at low speed, thereby preventing the rocker arm 6 from tilting.

Further, since the selector 10 is incorporated into one arm 8 and the actuator 20 is incorporated around the rocker shaft 9 of the valve swing mechanism, the rocker arm 6 swings except when the actuator 20 performs a switching operation. Even if the plunger 11, the lever member 12, and the actuator 20 are moved in the same manner, the positional relationship between the plunger 11, the lever member 12, and the actuator 20 does not change, and the connected or disconnected state of both arms 7 and 8 is reliably maintained.

In this valve train, the selector 10 is not limited to the one shown in the above specific example, but as shown in FIGS. 6 and 7, for example, the selector 10 is fitted into the rocker shaft 9 so as to be movable and rotatable in the axial direction, and the selector 10 is connected to the first arm. The selector 10 may be configured by a plunger 31 that is engaged with the second arm 7 and is detachable from the second arm 8 . That is, this plunger 31 is provided with an arc-shaped locking piece 32 along the outer circumferential surface of the rocker shaft 9, and on the inner circumferential surface of the arm portion 7a on one side of the first arm 7,
An arc-shaped engagement groove 33 is formed to insert and engage the locking piece 32, and an engagement groove 34 corresponding to the locking piece 32 is partially formed on the inner peripheral surface of the second arm 8. has been done. And the plunger 31 is
The locking piece 32 always engages with the engagement groove 33 of the first arm 7 and rotates together with the first arm 7, and when pushed to the right in FIG. Both arms 7 and 8 are connected by engaging with the engagement groove 34 of the second arm 8, and when pushed leftward, both arms 7 and 8 are disengaged from the engagement groove 34 of the second arm 8. 7 and 8 are kept in an unconnected state. In this case as well, a hydraulic actuator 35 equipped with a hydraulic chamber 36 and a return spring 37 and controlled by a control circuit or the like, or an actuator such as a solenoid, is incorporated into the valve operating swing mechanism, so that the plunger 31 moves according to the operating state. All you have to do is make sure that it is activated.

8 to 10 show the specific structure of the embodiment shown in FIG. 1E. In those figures, low-speed cams 4a,
4b, three cams are disposed on the camshaft 5, with a high-speed cam 3 in the center, and a rocker arm 6 is divided into a first arm 7 that abuts the high-speed cam 3 and a second arm 8. With,
Furthermore, this second arm 8 is connected to the intake valves 2a, 2
a valve-side arm 81 that comes into contact with b, and a pair of arm portions 8 that come into contact with the low-speed cams 4a and 4b, respectively.
2a and 82b, and a cam-side arm 82 integrally provided with cam-side arms 7, 81, and 82, which are supported around the rocker shaft 9 so as to be movable relative to each other. Then, the selector 10a that switches the valve side arm 81 and the cam side arm 82 of the second arm 8 between a connected state and a non-connected state is incorporated into the cam side arm 82 of the second arm 8, and the cam side arm 82 and the cam side arm 82 are connected to each other. A selector 10b that switches the first arm 7 between a connected state and a non-connected state is the first
It is incorporated into arm 7. These selectors 10
a, 10b are also connected to the plunger 11, similar to the selector 10 shown in the specific examples of FIGS. 2 to 5.
an actuator 20, which is constructed of lever members 12a, 12b and assembled around the rocker shaft 9 of the valve operating swing mechanism.
lever member 1 depending on the operating condition by a and 20b.
2a and 12b may be operated, or the structure may be as shown in FIGS. 6 and 7.

According to this valve train, the selector 10a is in the connected state, and the selector 1
If 0b is switched between the connected state and the disconnected state, the intake valves 2a and 2b are operated according to the rotation of the high-speed cam 3 at high speeds, and the first arm is operated according to the rotation of the high-speed cam 3 at low speeds. 7 is absorbed by the selector 10b and the low speed cam 4
Intake valves 2a and 2b are operated by rotation of a and 4b. Further, when the selector 10a is in the disconnected state, the force from any of the cams 3, 4a, 4b is no longer transmitted to the valve side arm 81, and the operation of the intake valves 2a, 2b is stopped. Therefore, according to this structure, the valve lift characteristics can be changed depending on the operating state, and the number of cylinders can also be controlled by stopping the operation of the valve of a specific cylinder. Other features are second
This embodiment is similar to the embodiment shown in FIGS.

Although the specific structure of each of the embodiments shown in FIGS. 1A, B, and C is not shown, the rocker arm 6 has a divided structure corresponding to each case, and the selector shown in the above specific example is used. This makes it easy to design. Now, to explain the functions and effects of each embodiment, the embodiments shown in FIGS. 1A and 1B have a simpler structure. According to the embodiment shown in FIG. 2C, the first arm 7 moves freely at low speeds when the low-speed cam 4 operates the intake valves 2a and 2b, while the high-speed cam 3 operates the intake valves 2a and 2b. Since the cam-side arm 82 of the second arm 8 moves freely at high speeds, the moment of inertia of the rocker arm 6 at high speeds can be further reduced.

Further, in each of the embodiments and specific examples described above, the device of the present invention is applied to an intake valve, but it may also be applied to an exhaust valve, or to both an intake valve and an exhaust valve.

〔Effect of the invention〕

As described above, the present invention has a structure for changing the valve lift characteristics by switching the linkage between a plurality of cams having different shapes of cam nose portions and the valve, in which a rocker arm is brought into contact with an arm that contacts some of the cams and the valve. The selector is divided into an arm and both arms are supported for relative movement around the rocker shaft, and a selector having a plunger that can be freely extended and retracted is incorporated in one of the arms, and the selector is operated in a plunger protruding state. Since both arms are switched between a connected state and a non-connected state using an actuator, the selector does not shake when compared with the conventional device shown in Japanese Utility Model Application Publication No. 57-182205. There is no
Not only can noise be reduced, but wear can also be suppressed and reliability can be increased. Furthermore, since the selector can be placed near the rocker shaft and the moment of inertia can be reduced, valve jumping at high speeds can be prevented and the engine speed limit can be increased. Also, compared to the conventional device disclosed in Japanese Patent Application Laid-open No. 57-110708, the above-mentioned arms are engaged and disengaged while being kept at a constant position in the axial direction of the rocker shaft, so the valve is not activated. can be performed smoothly. moreover,
Since a selector with a retractable plunger is incorporated into one arm and the actuator is incorporated into a swinging mechanism for a valve train, dimensional control is difficult compared to the device shown in U.S. Pat. No. 4,151,817. Although it is not necessary and has a simple structure, it has the effect of ensuring reliable operation.

[Brief explanation of the drawing]

1A to 1E are explanatory diagrams schematically showing various embodiments of the present invention, FIG. 2 is a plan view showing one specific example, FIG. 3 is a sectional view taken along the line -- in FIG. 2, and FIG. Fig. 2 is a sectional view taken along the line - Fig. 5 is a longitudinal sectional front view at the rocker shaft position, Fig. 6 is a view equivalent to Fig. 5 showing another example of the selector, Fig. 7 is an exploded perspective view of the same, Fig. 8
The figure is a plan view showing another specific example of the device of the present invention.
The figure is a sectional view taken along the line -- in FIG. 8, and FIG. 10 is a longitudinal sectional front view of this specific example device at the rocker shaft position. 2, 2a, 2b...Intake valve, 3, 3a, 3
b, 4, 4a, 4b... Multiple cams with different shapes, 6... Rocker arm, 7, 8... Divided arm, 9... Rocker shaft, 10, 1
0', 10a, 10b...Selector.

Claims (1)

[Claims] 1. A plurality of cams each having a cam nose portion with different shapes are provided, and the valve is selectively linked to one of the cams, and the linkage is switched depending on the operating condition, thereby increasing the lift of the valve. In an engine valve operating system that changes at least one of the amount or the valve opening period, a rocker arm that contacts the plurality of cams and the valve, and an arm that contacts some of the cams and a portion that contacts the valve are provided. The two arms are supported in a fixed position in the axial direction of the rocker shaft so as to be relatively movable around the rocker shaft, and one of the two arms is connected to the other arm. A selector having a plunger that can freely extend and retract in the direction of the arm is incorporated, and an actuator that operates the selector in a state in which the plunger is protruded is incorporated into a valve operating swing mechanism consisting of a rocker arm and a rocker shaft. The engine is characterized by comprising a switching device that switches between a disconnected state in which relative movement of both arms is permitted and a connected state in which the plunger protrudes and engages with the other arm to prevent relative movement between both arms. valve train.