JPS61250312A - Valve tappet device for engine - Google Patents

Abstract

PURPOSE:To smooth the change of the valve lift etc. by dividing rocker arms into the one that is in contact with a part of cams and the one that is in contact with a valve so that not only the relative motion of both arms can be enabled but also the change-over between a connecting state and a nonconnecting state can be enabled. CONSTITUTION:For an intake valve (exhaust valve) 2 provided on each cylinder, two cams 3 and 4 of a high-speed type and a low-speed type respectively and a rocker arm 6 are provided. The rocker arm 6 is divided into the first arm 7 being in contact with the high-speed type cam 3 and the second arm 8 whose one end has a contact part with the intake valve 2 and the other end is integrally provided with a contact part with the low-speed type cam 4. Both arms 7 and 8 do not move in the axial direction of a rocker shaft 9, and is so supported that the relative motion around the rocker shaft 9 is enabled in a state in which a given condition is maintained. And, in either of the arms 7 and 8, a selector 10 by which the changeover between a connecting state preventing relative motion and a nonconnecting state allowing relative motion of both arms 7 and 8 is incorporated.

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 opening period of intake and exhaust valves according to operating conditions.

(Prior art) When setting the operating characteristics of the engine's intake and exhaust valves, at low speeds, combustion stability and fuel efficiency are improved by suppressing exhaust blow-back and intake air blow-through during the valve overlap period at low speeds. Therefore, it is desirable to make the valve lift amount and the valve opening period relatively small, and at high speeds, it is desirable to increase the valve lift amount and the valve opening period in order to improve the output.

In order to satisfy these requirements, a valve train is equipped with multiple cams of different shapes, a valve is selectively linked to one of these cams, and the linkage is switched depending on the operating state. It is known in the past, and this type of valve train is known, for example, from Utility Model Application No. 57-18220.
There is something like the one shown in Publication No. 5. This device has two cams of a low speed type and a high speed type and one rocker arm for one valve, and the cam side portion of the rocker arm is formed into a bifurcated shape, and one end of the rocker arm is formed into a bifurcated shape. One end is used as the abutting part for the low-speed cam, and the other end is equipped with a slidable high-speed cam abutting member and a stopper that prevents the sliding, and this stopper is interlocked with an actuator such as a hydraulic cylinder. It operates through a mechanism. By controlling the actuator according to the operating condition, the high-speed cam abutting member moves loose when the speed is low, and the operation of the high-speed cam is not transmitted to the valve, and the valve is operated by the low-speed cam, and when the speed is high, the high-speed cam contact member moves freely, and the valve is operated by the low-speed cam when the speed is high. Sliding of the cam abutting member is prevented so that the operation of the high-speed cam is transmitted to the valve.

However, in this device, since a slidable member is provided in the part of the rocker arm that contacts the high-speed cam, a sliding gap is created between this member and the end of the rocker arm.
In addition, because the direction of the force applied to this member from the cam changes as the cam rotates, this member tends to wobble during operation, and such rattling causes noise and wear. This tends to occur and reduces reliability. In addition, this member and the stopper are installed at the end of the rocker arm located far from the rocker shaft, and furthermore,
Since the actuator and I*M structure are also installed on the rocker arm, the structure becomes complicated, and the moment of inertia of the rocker arm increases, making it easy for so-called valve jumping to occur during high-speed mouth expansion, which can cause damage to the engine. There was also the problem of a lower rotational speed limit.

In addition, as another valve train of this type, Japanese Patent Application Laid-Open No. 57-1
There is also a device as shown in Publication No. 10708. This device separately forms two cam-side arms (valve levers) that abut different-shaped cams and a valve-side arm (connection element) that abuts the valve, allowing these arms to rotate freely on the rocker shaft. The valve side arm is supported by the rocker shaft, and the valve side arm is movable in the axial direction of the rocker shaft, and an engaging portion 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. This valve side arm is selectively engaged with and connected to one of the cam side arms. However, with this device, 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 and inhibiting the smooth operation of the valve. There were some problems, such as ease of use.

(Objective of the Invention) In view of these circumstances, the present invention has a simple structure that allows changing the valve lift amount and valve opening period by switching the linkage between cams of different shapes and valves, and also eliminates backlash during operation. An engine that does not cause friction, prevents noise, improves reliability, reduces the moment of inertia of the rocker arm to increase the rotational speed limit, and allows smooth valve operation. The present invention provides a valve train.

(Structure of the Invention) The present invention provides a plurality of cams with different shapes, selectively links the valve to one of the cams, and switches the linkage depending on the operating state, thereby adjusting the lift amount or opening of the valve. In an engine valve train configured to change at least one of the periods, 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 arms are divided into two arms, 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 is incorporated into one of the arms, which can be switched to a disconnected state that allows relative movement of the arms, and which is switched depending on the operating state.

In other words, when the two arms are connected by the selector, the two arms swing together as one part of the cam rotates, and the operation of this part of the cam is transmitted to the valve. When both arms are disconnected, the two arms swing independently of each other, so the operation of some of the blades is not transmitted to the valve, and the valve is operated by the other cam. I try to do that.

(Embodiments) FIGS. 1(A) to 1(E) schematically show several embodiments of the apparatus of the present invention. In the embodiment shown in FIG. 1(A), 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. The arm 6 includes a first arm 7 that contacts the high-speed cam 3, and a second arm that has a contact portion that contacts the intake valve 2 at one end and a contact portion that contacts the low-speed cam 4 at the other end. Both arms 7.8 are supported so as to be movable relative to each other around the rocker shaft 9, without moving in the axial direction of the rocker shaft 9 and kept at a constant position. and both arms 7
．． A selector 10 that can be switched between a connected state that prevents the relative movement of the arms 7 and 8 and a non-connected state that allows the relative movement of both the arms 7 and 8 is built in one of the arms 7 and 8, and is operated by an actuating means not shown. The selector 10 is operated depending on the operating state. In the embodiment shown in FIG. 1 (8), a plurality of (for example, two) intake valves 2a per cylinder,
2b, the second arm 8 of the divided rocker arm 6 is provided with abutting portions 8a, 8b for the plurality of intake valves 2a, 2b, and the rest is as shown in FIG. It has the same structure as (A). In the embodiment shown in FIG. 1(C), the first arm 7 and the second
The second arm 8 of the rocker arm 6 is further divided into a valve-side arm 81 that contacts the intake valves 2a, 2b, and a cam-side arm 82 that contacts the low-speed cam 4. 82 are movable relative to each other around the rocker shaft 9, and selectors 10. 10' is provided so that when the selector 10 is in the connected state, the selector 10' is in the non-contact state. Figure 1 (D).

Each actual rotation in (E) will be explained in detail later by showing a specific example, but as shown in these figures, two high-speed cams 3a, 3b are used for each intake valve 2a, 2b per cylinder. and 1
Three or more cams are arranged, such as one low-speed cam 4 or a combination of one high-speed cam 3 and two low-speed cams 4a and 4b, and the rocker arm 6 is arranged accordingly.
and selector 10 or selectors 10a, 10
b may be used to switch the association.

2 to 5 show the specific structure of the embodiment shown in FIG. 1(D). In these figures, cylinder 1 of the engine
is equipped with two intake valves 2a, 2b and an exhaust valve (the exhaust valve and its drive system are not shown). Three cams are disposed on the camshaft 5, including a low-speed cam 4 and a low-speed cam 4 in the center. The high-speed cams 3a, 3b and the low-speed cam 4 are formed in different shapes, and the cam nose of the high-speed cam 3a is larger than the cam nose of the low-speed cam 4.
, 3b has a large cam nose. 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. (including shape),
Either one of these may be different.

A rocker arm 6 disposed between these cams 3a, 3b, 4 and the cylinder 1 has a pair of left and right arm portions 7a, 7b that contact both high-speed cams 3a, 3b, and a connecting portion 7 at the top.
a first arm 7 that is integrally connected via C, and a second arm 8 that is integrally provided with abutting portions 8a and 8b for both intake valves 2a and 2b, and an abutting portion 8C for the low-speed cam 4; The second arm 8 is divided into both arm parts 7 of the first arm 7.
It is located between a and 7b. And these arms 7
．． 8 is supported for relative movement around a rocker shaft 9.

A plunger 11 and a lever member 12 are incorporated into the first arm 7 as a selector 10 for switching the arms 7.8 between a connected state and a non-contact state. This selector 1
0 in detail, the upper part of the first arm 7 has a second
A guide hole 13 that opens toward the top of the arm 8 is formed, and the plunger 11 is movably housed in the guide hole 13, and the plunger 11 is brought into contact with the second arm 8 by a spring 14 in the guide hole 13. 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 large-diameter plunger insertion hole 16 and a locking hole 17 having a size corresponding to the engagement portion 15 and continuous with the plunger insertion hole 16 are formed. In this way, the lever member 1
When the lever member 12 moves to the lock position where the locking hole 17 of the second arm engages with the retaining portion 15 of the plunger 11, sliding of the plunger 11 is prevented, and both arms 7
．． 8 is prevented from moving in the direction in which the upper parts thereof approach each other (this time is the connected state), and on the other hand, the locking hole 17 is
5 and inserts the plunger 11 into the plunger insertion hole 16.
When the lever member 12 moves to the unlocked position where the plunger 11 is inserted, sliding of the plunger 11 is allowed, thereby allowing relative movement of both arms 7.8 (this is the time when the lever member 12 is unlocked). Connection Status).

The end of the lever member 12 protrudes outside the first arm 7 and is connected to an annular hydraulic actuator 20 provided around the rocker shaft 9 via an arm 12a. The hydraulic chamber 21
When oil is supplied from an oil pump (not shown) through the oil passage 22, the lever member 12 is moved toward the locking position, and when oil is relieved from the hydraulic chamber 21, the return spring 23 locks the lever member 12. The member 12 is moved toward the unlocked position. A control circuit 2 receives a rotation speed signal 24, etc.
5 controls the supply and discharge of oil to and from the hydraulic chamber 21 via the control valve 26 in the oil passage 22, so that the lever member 12 is placed in the lock position depending on the operating condition, for example, at high speeds above a predetermined rotation speed. The lever member 12 is operated to the unlocked position at low speeds below a predetermined rotation speed. The actuator for operating the lever member 12 is not limited to the above-mentioned hydraulic type, but a solenoid or the like may also be used, and the actuator is controlled according to the operating state according to the engine speed and load. It's okay.

In addition, 27 is an adjuster provided at one end of the second arm 8 facing the intake valve 2, 28 is an adjuster provided at the upper part of the second arm 8 facing the plunger 11,
These allow the valve clearance to be adjusted. Further, 29 is a 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 against the cam noses of the high-speed cams 3a and 3b. 2nd when rocking
Since the arm 8 is separated from the low-speed cam 4 and swings together with the first arm 7, the intake valves 2a, 2b are operated in accordance with the rotation of the high-speed cams 3a, 3b. 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 high-speed cam 3a,
The swinging of the first arm 7 caused by the rotation of the cam 3b is absorbed by the plunger 11 and is not transmitted to the second arm 8, and the swinging of the second arm 8 in response to the rotation of the low-speed cam 4 causes the intake valves 2a, 2b is activated. In this way, the valve lift characteristics can be changed to suit the operating conditions.

In particular, the high-speed cams 3a and 3b and the low-speed cam 4
A selector 10 for switching the linkage between the arms 7.8 and the intake valves 2a and 2b switches the arms 7.8 between a connected state and a non-connected state.
Unlike the conventional device disclosed in Japanese Patent No. 2205, the plunger 11 of this selector 10 is not in contact with a cam, so force always acts on the plunger 11 of the selector 10 in a fixed direction (the tangential direction of the rocker shaft 9). Even during operation, the plunger 11 does not shake.

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 compared to the case where the selector mechanism is provided at the cam side end of 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 are arranged, and at high speed, the two high-speed cams 3a, 3b on both sides close the intake valve 2a.
, 2b, and at low speed, the central low-speed cam 4 operates the intake valve 2a.

2b is activated, 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.

In this device, the selector 10 for switching the arms 7.8 between the connected state and the non-contact state depending on the operating state is not limited to the one shown in the above specific example, but is, for example, as shown in FIGS. 6 and 7. , the selector 10 may be configured by a plunger 31 that is fitted into the rocker shaft 9 so as to be movable in the axial direction and rotatable, engages with the first 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, whereas the above-mentioned locking piece 32 is provided 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 for inserting and engaging the piece 32, and the locking piece 32 is also formed on the inner peripheral surface of the second arm 8.
A corresponding engagement groove 34 is partially formed. The plunger 31 has its locking piece 32 constantly engaged with the engagement groove 33 of the first arm 7, rotates together with the first arm 7, and is pushed to the right in FIG. When the second arm 8 is engaged with the engagement groove 34 of the second arm 8, both arms 7
．． 8 is in a connected state, and when pushed to the left, both arms 7 are disengaged from the engagement groove 34 of the second arm 8.
．． 8 is in an unconnected state. In this case too,
a hydraulic actuator 35 that includes a hydraulic chamber 36 and a return spring 37 and is controlled by a restriction circuit or the like;
Alternatively, the plunger 31 may be operated by a solenoid or the like depending on the operating state.

8 to 10 show the specific structure of the embodiment shown in FIG. 1(E). In these figures, the intake valves 2a, 2
In contrast to b, three cams are disposed on the camshaft 5, with low-speed cams 4a and 4b on both sides and a high-speed cam 3 in the center, while a rocker arm 6 is connected to the high-speed cam 3.
The second arm 8 is divided into a first arm 7 that contacts the intake valve 2, and a second arm 8 that contacts the intake valve 2.
a.

2b and the low-speed cam 4a.
, 4b, a pair of arm portions 82a, 82, respectively.
The cam side arm 82 is integrally provided with a cam side arm 82, and these arms 7, 81, 82 are supported around the rocker shaft 9 so as to be able to move 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 incorporated in the first arm 7. These selectors 1Qa, 10b also have plungers 11a, 11b and lever members 12a, 1, similar to the selector 10 shown in the specific examples of FIGS.
2b so that the lever members 12a, 12b are actuated by external actuators 20a, 20b depending on the operating state, or a structure as shown in FIGS. 6 and 7 may be used.

According to this valve train, if the selector 10a is set in the connected state and the selector 10b is switched between the connected state and the disconnected state depending on high speed and low speed, the rotation of the high speed cam 3 is controlled at high speed. Accordingly, the intake valve 2a,
2b is operated, and at low speed, the swinging of the 11 arm 7 due to the rotation of the high speed cam 3 is absorbed by the selector 10b, and the intake valves 2a, 2b are operated by the rotation of the low speed cams 4a, 4b. Furthermore, when the selector 10a is in the disconnected state, the force from either cam 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 similar to the embodiments shown in FIGS. 2 to 5.

Although the specific structure of each of the embodiments shown in FIGS. It can be easily designed by using something like the one shown in Fig. 1 (A) and (B).
) the structure becomes simpler. Further, according to the embodiment shown in FIG. 2(C), at low speeds when the low-speed cam 4 operates the intake valves 2a, 2b, the first arm 7 moves freely, while the high-speed cam 3 operates the intake valves 2a, 2b.
At high speed when the second arm 8 is operated, the cam side arm 8 of the second arm 8
Since the rocker arm 2 moves freely, the moment of inertia of the rocker arm 6 at high speed can be further reduced.

Further, although the above embodiments and specific examples apply the present invention device to an intake valve, it may also be applied to an exhaust valve.
Alternatively, it may be applied to both the intake valve and the exhaust valve.

(Effects of the Invention) As described above, the present invention provides a structure for changing the valve lift characteristics by switching the linkage between a plurality of cams and valves having different shapes. The structure is divided into an arm that comes into contact with the rocker shaft, and both arms can be moved relative to each other around the rocker shaft, and a selector built into one of the arms can be used to switch between a connected state and a non-connected state. When compared with the conventional device shown in Japanese Utility Model Application Publication No. 57-182205, there is no rattling in the selector, noise can be reduced, wear can be suppressed, and reliability can be improved. 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, JP-A-57-
Even compared to the conventional device shown in Publication No. 110708,
Since both arms are engaged and disengaged while being maintained at a constant position in the axial direction of the rocker shaft, the valve can be operated smoothly.

[Brief explanation of drawings]

Figures 1 (A) to (E) are explanatory diagrams schematically showing various embodiments of the present invention, Figure 2 is a plan view showing an example of an integrated body, and Figure 3 is a sectional view taken along the line ■-■ of Figure 2. , FIG. 4 shows rV-IV in FIG.
5 is a longitudinal sectional front view at the rocker shaft position, FIG. 6 is a view corresponding to FIG. 5 showing another example of the selector, FIG. 7 is an exploded perspective view of the same, and FIG. 8 is the device of the present invention. 9 is a plan view showing another specific example of
, 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, 3b. 4.4a, 4b... multiple cams with different shapes, 6...
・Rocker arm, 7, 8...divided arm, 9
...Rocker shaft, 10.10', 10a, 1
0b...Selector. Patent applicant Mazda Co., Ltd. Agent
Patent Attorney Etsushi Kotani Patent Attorney
Long 1) Masamukai Patent Attorney Yasuo Itaya No. 1m (A> (B)
(Go) (9)
(E) Figure 2 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. By providing multiple cams with different shapes, selectively linking the valve to one of the cams, and switching the linkage depending on the operating condition, at least one of the valve lift amount or valve opening period can be changed. In such an engine valve train, the rocker arm that contacts the plurality of cams and valves is divided into an arm that contacts some of the cams and an arm that has a portion that contacts the valve, and both arms is supported in a fixed position in the axial direction of the rocker shaft so that it can move relative to the rocker shaft, and there is a connected state that prevents relative movement of both arms, and a disconnected state that allows relative movement of both arms. 1. A valve train for an engine, characterized in that a selector is incorporated in one of the arms and is switchable depending on the operating state.