JPH0239602B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Application Field The present invention provides a plurality of cam followers that are swingable in order to open an intake valve or an exhaust valve that has been biased in the valve-closing direction. The camshaft is pivotally supported on the shaft and driven to rotate in synchronization with the rotation of the engine, and a cam for swinging the cam follower is integrated into the camshaft.
The present invention relates to a valve operation changing device for an internal combustion engine, in which each cam follower is provided with a connecting mechanism including a piston that is movable between a position where a plurality of cam followers are connected and a position where the connected state is released.

(2) Prior art This device has already been proposed by the applicant (Japanese Patent Application No. 58-238423) (Japanese Unexamined Patent Publication No. 128914/1982), and is a device that uses a connecting mechanism to connect the first cam follower. When the second rocker arm is connected, the cam swings both rocker arms to open and close all the intake valves or all the exhaust valves, and when the connecting state of each rocker arm by the connecting mechanism is released, a part of the rocker arm is opened and closed. By swinging only the rocker arm, only one intake valve or exhaust valve is opened or closed. By the way, when switching the connection state in the connection mechanism as described above, it is necessary that both rocker arms are not swinging, that is, the first rocker arm is in sliding contact with the base circle of the cam. It is. For example, when switching from a state in which only one intake valve or exhaust valve is opened and closed to a state in which both intake valves or both exhaust valves are opened and closed, the intake valve or exhaust valve is Assume that the piston starts moving to connect both rocker arms by the coupling mechanism at time t ₁ in the valve closing period Ac of the valve, that is, the region where the first rocker arm is in sliding contact with the base circle of the cam and is stationary. do. In this case, since the intake valve or the exhaust valve enters the opening period Ao, that is, the swinging movement period of the first rocker arm, it becomes difficult to engage the second rocker arm of the piston, and even if it is slightly engaged, the The engaged state may be released in the process, and reliable switching cannot be performed. On the other hand, when the piston starts moving at times t ₂ and t ₃ of the valve-opening interval Ao, the piston cannot engage at that time, but from the beginning of the next valve-closing interval Ac. Since the piston can be moved, switching can be performed reliably.

As described above, depending on when the coupling mechanism starts operating, the coupling and disassociation of both rocker arms may not be performed smoothly, and if the switching is not carried out smoothly, abnormal noise may be generated or damage may occur. This is not desirable as it may cause

(3) Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and sets the actual operation start time of the coupling mechanism to the next valve closing period after the valve opening period. An object of the present invention is to provide a valve operation changing device for an internal combustion engine that reliably switches the connected state by a connecting mechanism from the beginning.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a method in which a plurality of cam followers are used to open an intake valve or an exhaust valve that is biased in the valve-closing direction. A cam for driving cam followers is integrated into the camshaft, which is swingably supported on the shaft and driven to rotate in synchronization with the rotation of the engine, and each cam follower has a position that connects the cam followers. In the valve operation changing device for an internal combustion engine, the coupling mechanism is provided with a piston that is movable between a position where the cam follower is disengaged, and a position where the shaft is disengaged. a displaceable timing plate is provided so as to project into a recess provided in at least one cam follower and engage said piston when it is in position relative to the engine body, said one cam follower being able to engage said piston; Relative mounting of the timing plate to the one cam follower such that when operating in the valve opening direction, the cam follower leaves the timing plate in the predetermined position and disengages the timing plate from the piston. The feature is that the location is set.

(2) Effect The piston output is possible only when the cam follower is swinging in the valve opening direction, so the actual operation of the coupling mechanism starts in the next period after the valve opening period ends. This is the beginning of the valve closing section.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIGS. 1 and 2, a pair of intake valves V1 and V2 provided in the engine body 1 are shown.
is biased in the valve closing direction by valve springs S1 and S2. These intake valves V1 and V2 are connected to a cam 4 that is integrally provided to a camshaft 3 that is driven to rotate at a rotation ratio of 1/2 in synchronization with the rotation of the engine, and a rock shaft 5 that is a shaft parallel to the camshaft 3. Only one intake valve V1 is opened and closed by the functions of the first and second rocker arms 6, 7 as cam followers that are swingably supported by the rocker arm 6, 7, and the coupling mechanism 8 provided on both the rocker arms 6, 7. The opening and closing operation is performed by switching between the state and the state in which both intake valves V1 and V2 are both opened and closed.
The engine body 1 also includes a pair of exhaust valves (not shown).
These exhaust valves are also opened and closed in the same manner as the intake valves V1 and V2.

The camshaft 3 is rotatably disposed above the engine body 1, and the cam 4 is integrally provided on the camshaft 3 at a position corresponding to one intake valve V1. The cam 4 has a base circle 4a concentric with the camshaft 3 and a high portion 4b projecting radially outward from the base circle 4a. Further, a raised portion 9 having the same diameter as the base circle 4a is integrally provided on the camshaft 3 at a position corresponding to the other intake valve V2.

The lock shaft 5 is fixedly arranged below the camshaft 3.
In this case, a first rocker arm 6 corresponding to one intake valve V1 and a second rocker arm 7 corresponding to the other intake valve V2 are supported in sliding contact with each other so as to be capable of relative angular displacement. Tappet screws T1 and T2, which can abut the upper ends of the intake valves V1 and V2, are screwed into the ends of the rocker arms 6 and 7 located above the intake valves V1 and V2, respectively, so as to be movable forward and backward.

A cam slipper 6a that slides on the cam 4 is integrally provided on the upper part of the first rocker arm 6, and the first rocker arm 6 swings in response to the rotation of the cam 4. In other words, the first rocker arm 6 is
When the cam slipper 6a is in sliding contact with the base circle 4a of the cam 4, it remains stationary, and when the cam slipper 6a comes into sliding contact with the high part 4b of the cam 4, it rotates downward while contracting the valve spring S1. Open the intake valve V1.

Further, the upper part of the second rocker arm 7 has a raised portion 9.
A slipper 7a is provided which slides into contact with the second locker arm 7, and this protrusion 9 slides against the second locker arm 7 when the locker arms 6 and 7 are disengaged, that is, when the intake valve V2 is in the closed state. It prevents it from jumping up and keeps it stationary.

In FIG. 3, a connecting mechanism 8 for connecting and disconnecting the first and second rocker arms 6, 7 is movable between a position where both rocker arms 6, 7 are connected and a position where the connected state is released. a piston 11, a stopper 12 that restricts the movement of the piston 11, a spring 13 that biases the stopper 12 to push the piston 11 toward the disconnection position, and a timing plate 14 that controls the movement timing of the piston 11. Equipped with.

The first locking arm 6 has a second locking arm 7.
A first guide hole 15 that opens toward the side and is parallel to the rocker shaft 5 is bored, and a regulating step 16 facing the second rocker arm 7 is provided at the bottom side of the first guide hole 15. A small diameter portion 17 is provided. The piston 11 is slid into the first guide hole 15 .

The piston 11 includes a bottomed cylindrical connecting body 18,
A short cylindrical pressing body 19 has a spring 20 between them.
They are formed by sliding each other with the two intervening. The connecting body 18 is slid into the first guide hole 15 with its open end facing toward the bottom side of the first guide hole 15 . Moreover, the connecting body 18
The inner diameter of the guide hole 15 is set to be smaller than the small diameter portion 17 of the first guide hole 15 . Further, the pressing body 19 is slid onto the small diameter portion 16 with one end facing toward the bottom of the first guide hole 15, thereby defining a hydraulic chamber 21 between the pressing body 19 and the bottom of the first guide hole 15. . Moreover, a protrusion 23 is provided on the connecting body 18 side of the pressing body 19 via a step 22, and this protrusion 23
is slid onto the connecting body 18. A spring chamber 24 is defined between the connecting body 18 and the pressing body 19, and a spring 20 that biases the connecting body 18 and the pressing body 19 in a direction away from each other is housed in the spring chamber 24.
The set load of this spring 20 is set smaller than that of the spring 13.

With the connecting body 18 in contact with the regulating step 16,
When the pressing body 19 is moved to the maximum extent toward the hydraulic chamber 21 by the spring 20, there is an annular shape that can be engaged with the timing plate 14 between the open end surface of the connecting body 18 and the stepped portion 22 of the pressing body 19. An engagement groove 26 is formed.

The length of the connecting body 18 is set such that its open end surface is in contact with the regulating step 16 and its closed end surface is located between the opposing side surfaces of the first and second rocker arms 6 and 7.

An oil passage 27 communicating with the hydraulic chamber 21 is bored in the first rocker arm 6 . Further, within the rocker shaft 5, a hydraulic oil passage 28 is provided for supplying hydraulic oil from a hydraulic pressure supply source (not shown).
The oil passage 27 and the hydraulic oil passage 28 are always communicated through a communication hole 29 formed in the side wall of the rocker shaft 5 even when the first rocker arm 6 is in such a state.

The second rocker arm 7 has a second guide hole 30 corresponding to the first guide hole 15 in the first rocker arm 7.
The second guide hole 30 is drilled so as to open toward the side, and the stopper 12 is slid into this second guide hole 30 . The stopper 12 is formed into a disk shape and can slide inside the second guide hole 30 until it comes into contact with a regulating step 31 provided halfway through the second guide hole 30 facing the first rocker arm 6 side. It is. Further, an insertion hole 32 is bored at the bottom of the second guide hole 30.
A guide rod 33 integral with the stopper 12 is inserted into the insertion hole 32. As a result, the stopper 12
slides with its axis always aligned with the second guide hole 30.

A coiled spring 13 surrounding the guide rod 33 is interposed between the bottom surface of the second guide hole 30 and the stopper 12, and the stopper 12 is moved in the direction of contacting the piston 11 by the spring force of the spring 13. energized.

A through hole 34 is bored in the stopper 12 and the guide rod 33, and a hole 34 is formed in the closed end surface of the connecting body 18 in the piston 11 in correspondence with the through hole 34.
5 is drilled. The spring chamber 24 of the piston 11 is
It is always communicated with the outside through the through hole 34 and the hole 35, and therefore the inside of the spring chamber 24 is not pressurized or depressurized in response to the movement of the connecting body 18 and the pressing body 19 toward and away from each other. The movement of the body 18 and the pressing body 19 toward and away from each other is performed quickly.

The outer surface of the pressing body 19 is provided with an annular engagement groove 36 into which the timing plate 14 can engage, similar to the engagement groove 36 described above. The position of this engagement groove 36 is determined when hydraulic pressure acts on the hydraulic chamber 21, the pressing body 19 is displaced to the maximum extent toward the second rocker arm 7, and both rocker arms 6, 7 are completely connected by the connecting body 18. , so that the timing plate 14 can be engaged.

A groove 37 is provided in the upper part of the first rocker arm 6 as a recess into which the timing plate 14 is slid. It is attached to the first rocker arm 6.
Furthermore, the groove 37 is provided so as to face the middle of the first guide hole 15, and a part of the outer surface of the piston 11 is exposed to the groove 37.

In FIGS. 4 and 5, timing plate 1
4 includes a disc-shaped base 38, an arm 39 which is connected to the upper part of the base 38 and is bent and formed so as to extend to both sides of the base 38, and which is connected to the end of the arm 39. It consists of a locking part 40. The base 38 has holes 4
1 is drilled. The first locking arm 6 also has a boss portion 6b surrounding the locking shaft 5.
The timing plate 14 is attached to the first rocker arm 6 so that the boss portion 6b is inserted into the hole 41. Therefore, the timing plate 14
This enables relative angular displacement with the first rocker arm 6 around the axis of the rocker shaft 5.

When the timing plate 14 is attached to the first rocker arm 6, the locking portion 40 is attached to the first rocker arm 6.
The torsion spring 42 is interposed between the engine body 1 and the timing plate 14 so that the locking portion 40 of the timing plate 14 extends toward the groove 37 side.
is biased in the direction of sliding together. In addition, the engine body 1
A stopper pin 43 that can come into contact with the arm 39 of the timing plate 14 is implanted in the stopper pin 43 , and the arm portion 39 of the timing plate 14 resiliently comes into contact with the stopper pin 43 due to the spring force of the torsion spring 42 . Moreover,
In this state, when the first rocker arm 6 is in a stationary state, the locking part 40 engages with the engagement grooves 26, 36, and when the first rocker arm 6 swings in the valve opening direction, the locking part 40 engages with the engagement grooves 26, 36. The position of the stopper pin 43 is set so that the locking portion 40 is released. Furthermore, the shape of the locking portion 40 is different from that of the first locking arm 6.
Regardless of the swinging state of the groove 37, the groove 37 is always slidable.

Next, the operation of this embodiment will be explained. When no hydraulic pressure is applied to the hydraulic chamber 21, the stopper 12 biased by the spring 13 causes the connecting body to
8 is pressed until it comes into contact with the regulating step 16, and the pressing body 19 is displaced to the maximum extent toward the hydraulic chamber 21 by the spring 20. In this state, the engagement groove 2
6 is formed so that the timing plate 14 can engage with the engagement groove 26 as shown in FIG. 2 when the first rocker arm 6 is at rest.

At this time, the connecting body 18 in the piston 11,
The stopper 12 is in contact with the opposite side surfaces of the first and second rocker arms 6, 7, and the first and second rocker arms 6, 7 are not connected. Therefore, the first rocker arm 6 swings in response to the rotation of the cam 4, but the second rocker arm 7 remains stationary, and only the first rocker arm 6 makes sliding contact between the connecting body 18 and the stopper 12. The intake valve V1 only opens and closes.

Here, assume that hydraulic pressure is applied to the hydraulic chamber ₂₁ at time t1 in FIG. Due to the action of this oil pressure, the pressing body 19 of the piston 11 tries to start moving, but since the timing plate 14 is engaged with the engagement groove 26, the movement of the pressing body 19 is blocked, and the piston 11 maintains the state shown in FIG.

In this state, when the first rocker arm 6 starts swinging in the valve opening direction, that is, when it enters the valve opening section Ao, the first rocker arm 6 leaves the timing plate 14 behind as shown in FIG. The timing plate 14 is rotated, and the engagement state of the timing plate 14 with the engagement groove 26 is released. This allows the pressing body 19 to move, and the pressing body 19 moves until it comes into contact with the connecting body 18. Therefore, even when the first rocker arm 6 rotates upward and enters the valve closing section Ac, the timing plate 14 does not engage the engagement groove 26 and the pressing body 1
The piston 11 is allowed to move by contacting the outer surface of the piston 9.

In this way, the first and second guide holes 1
When the axes of the pistons 5 and 30 coincide, that is, when the first rocker arm 6 is stationary and enters the valve closing section Ac, the piston 11 starts moving toward the second guide hole 30 side. This causes the connecting body 18 to move to the second position.
Since it slides into the guide hole 30 and the first and second rocker arms 6, 7 are connected via the coupling mechanism 8, the second rocker arm 7 starts to swing together with the first rocker arm 6, and both intake valves V1, V2 both open and close.

When this connection is completed, the engagement groove 36 of the pressing body 19 is at the position corresponding to the groove 37, and the timing plate 1 is in the valve opening section Ac.
4 engages with the engagement groove 36.

Next, assume that the hydraulic pressure in the hydraulic chamber 21 is released at time t ₁ of the valve closing section Ac. Due to the release of this hydraulic pressure, the piston 11 is pushed by the spring 13 in the direction of leaving the second guide hole 30, but the engagement groove 3
Since the timing plate 14 is engaged with the piston 6, movement of the piston 11 is prevented. Next, when entering the valve opening section Ao, the timing plate 14 is disengaged from the engagement groove 36 according to the swinging motion of the first rocker arm 6, and the pressing body 19 is moved toward the hydraulic chamber 21 by the spring 20. At this time, the connecting body 18 moves through the first and second guide holes 1 as the first rocker arm 6 swings.
5 and 30, it does not return to the first guide hole 15, but moves into the first guide hole 15 when entering the next valve closing section Ac, and returns to the state shown in FIG. 3.

To summarize the operation of the coupling mechanism 8, in FIG. 7, the section At where the timing plate 14 is disengaged from the engagement groove 26 or 36 has a width that is slightly shorter than the valve opening section Ao due to its mechanism. , when hydraulic pressure is supplied to or released from the hydraulic chamber 21 at times t ₂ and t ₃ within that section At,
The switching operation of the coupling mechanism 8 is reliably performed in the next valve closing section Ac. Further, when the hydraulic pressure is supplied to or released from the hydraulic chamber 21 at a time other than the interval At, for example, at _t1 , as shown by the broken line arrow, 1
Reliable switching is performed in the next valve-closing interval Ac beyond the two interval At.

In the above description, the portions related to the intake valves V1 and V2 have been described, but the pair of exhaust valves are also operated in the same manner as the intake valves V1 and V2. Further, the valve operation changing device according to the present invention may be provided in connection with only one of the intake valves V1 and V2 and the pair of exhaust valves.

C. Effects of the Invention As described above, according to the present invention, in order to open the intake valve or exhaust valve that is biased in the valve-closing direction,
A plurality of cam followers are pivotally supported on the shaft, and a cam for driving the cam followers is integrated into the camshaft, which is rotationally driven in synchronization with the rotation of the engine. In a valve operation changing device for an internal combustion engine, which is provided with a connecting mechanism including a piston that is movable between a position where the cam follower is connected and a position where the connected state is released, A timing plate capable of relative rocking displacement is provided so as to be able to project into a recess provided in at least one cam follower and engage the piston when the timing plate is in a predetermined position with respect to the engine body, a timing plate for the one cam follower such that when the two cam followers are operating in the valve opening direction, the cam follower leaves the timing plate at the predetermined position and releases the engagement between the timing plate and the piston; Since the relative mounting position of the cam follower is set, no matter when the connection mechanism starts operating, the actual start time of the connection mechanism will be at the beginning of the valve closing period, and therefore the cam follower will not be able to switch to the connected state. This can be done reliably, contributing to the prevention of abnormal noises and damage to the coupling mechanism.

In particular, the timing plate, which determines the actuation timing of the coupling mechanism, can be directly engaged with and disengaged from the piston of the coupling mechanism to restrict and release the movement of the piston, making it possible to accurately and reliably control the movement of the piston. This allows the connection mechanism to be switched accurately at all times.

Furthermore, since the timing plate is projected into the recess of the cam follower when engaged with the piston, the operating space for the timing plate can be reduced, and the timing plate is left behind in the cam follower and is not connected to the piston. Since the engagement is released, there is no need to provide a special cam mechanism between the timing plate and the engine body or the cam follower to make the timing plate respond to the rocking of the cam follower. This can greatly contribute to simplification and downsizing of the indoor structure.

Furthermore, since the timing plate can be oscillated relative to the cam follower around the shaft, there is an advantage that the timing plate and its related parts are not added to the inertial mass of the valve system.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a plan view, FIG. 2 is a sectional view taken along the line -- in FIG. 1, FIG. 3 is a sectional view taken along the line -- in FIG. 1, FIG. 5 is a perspective view of the timing plate and stopper pin, FIG. 6 is a sectional view corresponding to FIG. 2 when the first rocker arm is swinging in the valve opening direction, and FIG. FIG. 7 is an explanatory diagram showing the relationship between the valve operation timing and the operation timing of the coupling mechanism. 3...Camshaft, 4...Cam, 5...Rock shaft as a shaft, 6, 7...Rock arm as a cam follower, 8...Connection mechanism,
11... Piston, 14... Timing plate, 37
...Groove as a recess, V1, V2...Intake valve.

Claims (1)

[Claims] 1. A plurality of cam followers 6, 7 are swingably supported on the shaft 5 to open the intake valves V1, V2 or the exhaust valves which are biased in the valve closing direction. A cam 4 for driving cam followers 6 and 7 is integrated into a camshaft 3 that is rotationally driven in synchronization with the rotation, and each cam follower 6 and 7 has a
A coupling mechanism 8 is provided which includes a piston 11 that is movable between a position where the cam followers 6 and 7 are coupled and a position where the coupling state is released.
In a valve operation changing device for an internal combustion engine, the engine body 1
Therein is a timing plate 1 which can be oscillated relative to the cam followers 6 and 7 around the shaft 5.
4 is provided so that it can project into a recess 37 provided in at least one cam follower 6 and engage with the piston 11 when it is in a predetermined position with respect to the engine body 1, and the one cam follower 6 when the cam follower 6 is operating in the valve opening direction.
The timing plate 14 is left in the predetermined position and the timing plate 14 and the piston 11 are removed.
A valve operation changing device for an internal combustion engine, characterized in that the relative mounting position of the timing plate 14 with respect to the one cam follower 6 is set so as to release the engagement with the one cam follower 6. 2 The timing plate 14 is attached to the one cam follower 6 so as to allow relative angular displacement around the axis of the shaft 5, and
The valve operation changing device for an internal combustion engine according to claim 1, wherein the valve operation changing device for an internal combustion engine is resiliently abutted against a stopper pin 43 fixed to the engine body 1 in order to prevent the valve from following the operation. .