JPH0418122B2 - - Google Patents

Description

Detailed Description of the Invention A. Purpose of the Invention (1) Industrial Field of Application The present invention provides a means for a plurality of cam followers, including a cam follower interlocked and connected to an intake valve or an exhaust valve, to interact with each other according to the rotation of a camshaft. A valve train for an internal combustion engine in which the cam followers are arranged adjacent to each other and commonly supported on a support shaft to enable rotational movement in different modes, and a connection switching mechanism is provided between each cam follower to switch between mutual connection and disconnection. Regarding equipment.

(2) Conventional technology Conventionally, such a valve train is disclosed in, for example, Japanese Patent Application Laid-open No. 1983-
It is known from the publication No. 250318.

(3) Problems to be Solved by the Invention However, in the above-mentioned conventional method, an engagement hole extending in a direction perpendicular to the opposing surfaces of the adjacent cam followers is formed in the opposing surfaces of the cam followers that face each other in a connected state. A connecting pin that is open and slidable in the engagement hole is configured to be movable between a connecting position in which it straddles and connects both cam followers and a releasing position in which the connection is released. ing. Therefore, when the pin is in the connected position, the pin receives a shearing force in the direction across the pin or a bending force in the longitudinal direction of the pin from both cam followers that are about to swing relative to each other. If this is to have the necessary strength, it must be made relatively long and thick, which is disadvantageous in terms of downsizing the connection switching mechanism and improving responsiveness during switching.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve operating system for an internal combustion engine that can solve the problems of the conventional systems described above.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the present invention, a plurality of cam followers, including a cam follower interlocked and connected to an intake valve or an exhaust valve, are configured to rotate according to the rotation of a camshaft. The cam followers are commonly supported on a support shaft and arranged adjacently, and a connection switching mechanism is provided between each cam follower to enable mutual connection and disconnection. In a valve train for an engine, the connection switching mechanism includes an engagement recess that is formed across opposing surfaces of adjacent cam followers in a connected state and extends along the opposing surfaces, and each cam follower. a support body disposed separately from the support body; a connection position disposed along the opposing surface and engaged with the engagement recess; and a connection release position disengaged from the engagement recess and housed in the support body. and a connecting pin movable along the opposing surfaces between the connecting pins.

(2) Effect According to the above configuration, when the connecting pin is in the connecting position, the pin receives a shearing force in a direction that vertically splits the pin from both cam followers that are about to swing relative to each other, and It is not subjected to bending force. Therefore, even if the connecting pin is formed to be relatively short, lightweight, and compact, the necessary strength can be ensured.

(3) Embodiment Hereinafter, embodiments of the present invention will be explained with reference to the drawings. First, in FIGS. 1 and 2 showing an embodiment of the present invention, an intake valve 1 provided in the engine body E is A low-speed cam 4 and a high-speed cam 5 are provided integrally with a camshaft 2 that is rotatably driven from the crankshaft at a reduction ratio of 1/2, and are pivotally supported by a rock shaft 6 that serves as a support shaft parallel to the camshaft 2. It is driven to open and close by the functions of the first rocker arm 7 and the second rocker arm 8 as cam followers, and a connection switching mechanism 10 that can switch between connecting and disconnecting both the rocker arms 7 and 8.

The camshaft 2 is rotatably disposed above the engine body E, the low-speed cam 4 is integrated into the camshaft 2 at a position corresponding to the intake valve 1, and the high-speed cam 5 is adjacent to the low-speed cam 4. and is integrated into the camshaft 2. The low-speed cam 4 has a high portion 4a with a relatively small protrusion amount along the radial direction of the camshaft 2 and a base circular portion 4b, and the high-speed cam 5 has a relatively small protrusion amount along the radial direction of the camshaft 2. It has a high part 5a with a large target and a base circular part 5b.

The rocker shaft 6 is fixedly arranged above the intermediate portion between the camshaft 2 and the intake valve 1. A first rocker arm 7, which is interlocked and connected to the intake valve 1, and a second rocker arm 8, which is adjacent to the first rocker arm 7, are rotatably supported by the rocker shaft 6 around the same axis. The first rocker arm 7 is provided with a cam slipper 11 that slides into contact with the low-speed cam 4 from above, and is also provided with a connecting arm portion 12 that extends on the opposite side of the cam slipper 11 and is interlocked and connected to the intake valve 1. , second
The rocker arm 8 is provided with a cam slipper 13 that slides into contact with the high-speed cam 5 from above.

A flange 14 is provided on the upper part of the intake valve 1. A valve spring 15 is interposed between the flange 14 and the engine body E.
is urged in the valve closing direction, that is, upward. Further, a tappet screw 16 that can come into contact with the upper end of the intake valve 1 is screwed into the tip of the connecting arm 12 of the first rocker arm 7 so as to be movable forward and backward.

A cylindrical portion 17 extending toward the first rocker arm 7 is integrally provided at the base of the second rocker arm 8, and the rocker shaft 6 is inserted through the cylindrical portion 17. Further, a support hole 18 for inserting the cylindrical portion 17 is bored in the intermediate portion of the first locker arm 7, and by inserting the cylindrical portion 17 into the support hole 18, the first and second locker arms 7 , 8 can rotate around the same axis. Moreover, support hole 1
8, the tip of the cylindrical portion 17 is flush with the side surface of the first rocker arm 7.

A torsion spring 20 surrounding the rocker shaft 6 is interposed between the second rocker arm 8 and an engaging portion 19 fixedly provided on the engine body E, and the spring force of this torsion spring 20 The two-rocker arm 8 is biased in a direction to bring its cam slipper 13 into sliding contact with the high-speed cam 5. On the other hand, the first rocker arm 7 is biased by the valve spring 15 in a direction in which the cam slipper 11 slides into contact with the low-speed cam 4.

Referring also to FIG. 3, both rocker arms 7,
A connection switching mechanism 10 for switching between connection and disconnection of the cylindrical portion 17 and the side surface of the first rocker arm 7 includes a support member that is pivotally supported on the rocker shaft 6 and connected to the first rocker arm 7 . The outer peripheral surface of the cylindrical portion 17 and the inner peripheral surface of the first rocker arm 7 are formed so as to straddle the case 21 as a case 21, the outer peripheral surface of the cylindrical portion 17 as the opposing surfaces 7a and 8a, and the inner peripheral surface of the first rocker arm 7, which are opposing surfaces 7a and 8a of the rocker arms 7 and 8, which face each other in the connected state. Engagement recess 30 extending along opposing surfaces 7a, 8a
and is slidable along the opposing surfaces 7a and 8a between a connecting position where it engages with the engaging recess 30 and a disconnecting position where it separates from the engaging recess 30 and is housed in the case 21. connecting pin 22 and connecting pin 22
and a hydraulic chamber 23 defined between the case 21;
A return spring 24 is provided between the case 21 and the connecting pin 22 to urge the connecting pin 22 toward the hydraulic chamber 23 .

The case 21 is formed into a cylindrical shape surrounding the rocker shaft 6, and is integrally provided with an engaging arm 25 that engages the cam slipper 11 of the first rocker arm 7 from above. In addition, a torsion spring 27 is interposed between the case 21 and an engaging portion 26 fixed to the engine body E, and the spring force of the torsion spring 27 causes the case 21 to move its engaging arm 25 upward. It is rotationally biased in the direction of engagement with the cam slipper 11. As a result, the case 21 is connected to the first rocker arm 7 and swings as a result of the first rocker arm 7.

When the cam slippers 11 and 13 of the first and second rocker arms 7 and 8 are in sliding contact with the base circular parts 4b and 5b of both cams 4 and 5, the tip of the cylindrical portion 17 and the side surface of the first rocker arm 7 are Semicircular notches 28, 2 that cooperate to form a circular engagement recess 30 having an axis parallel to the axis of the rock shaft 6
9 is provided open to the case 21 side.

On the other hand, the case 21 has a small-diameter hole 31 that opens toward both rocker arms 7 and 8 in correspondence with the engagement recess 30, and a large-diameter hole 33 coaxially connected to the small-diameter hole 31 via a step 32. , are bored parallel to the rocker shaft 6, and the end of the large diameter hole 33 is closed with an end plate 34 on the side opposite to both the rocker shafts 7, 8. Moreover, the inner diameter of the small diameter hole 31 is set corresponding to the inner diameter of the engagement recess 30.

The connecting pin 22 is slidably fitted into the small diameter hole 31, and there is a part in the middle of the connecting pin 22 that is slidably fitted into the large diameter hole 33 and is connected to the end plate 34. A large-diameter portion 22a defining a hydraulic chamber 23 is provided. Further, a return spring 24 is compressed between the large diameter portion 22a and the step portion 32, and the connecting pin 2
2 is urged toward the hydraulic chamber 23 by the return spring 24.

In this connection switching mechanism 10, when the hydraulic pressure in the hydraulic chamber 23 is released, the connecting pin 22 is retracted toward the hydraulic chamber 23 by the spring force of the return spring 24, and in this state, the tip of the connecting pin 22 is It is housed in the small diameter hole 31. Therefore, the cylindrical portion 17
That is, the second rocker arm 8 and the first rocker arm 7 are in a disconnected state. On the other hand, when hydraulic pressure is supplied to the hydraulic chamber 23, the connecting pin 22 moves forward against the spring force of the return spring 24, and both rocker arms 7, 8 slide into base circular parts 4b, 5b of the cams 4, 5. When the engagement recess 30 is formed, it fits into the engagement recess 30. Therefore, the cylindrical portion 17, that is, the second rocker arm 8 and the first rocker arm 7
and are connected to each other via a connecting pin 22.

A hydraulic pressure supply passage 35 leading to a hydraulic pressure supply source (not shown) is bored in the rock shaft 6, and in order to communicate the hydraulic pressure supply passage 35 with the hydraulic chamber 23, an oil passage 36 communicating with the hydraulic chamber 23 is provided in the case 21.
The oil passage 36 is connected to the hydraulic pressure supply passage 3 through an oil hole 37 bored on the side wall of the rocker shaft 6.
5 is constantly communicated with.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, the hydraulic pressure in the hydraulic chamber 23 is released, and the connecting pin 22 is retreated toward the hydraulic chamber 23 by the spring force of the return spring 24. Therefore, both rocker arms 7 and 8 are not connected, and the first rocker arm 7 swings according to the rotation of the camshaft 2, and the intake valve 1 adjusts the timing and timing according to the shape of the low-speed cam 4 accordingly. It opens and closes depending on the amount of lift.

Further, during high-speed operation of the engine, hydraulic pressure is supplied to the hydraulic chamber 23. In response to this, the connecting pin 22 moves forward against the spring force of the return spring 24 and enters the engagement recess 30 with both locking arms 7 and 8 in sliding contact with the base circular parts 4b and 5b of the cams 4 and 5. Fit together. As a result, both rocker arms 7 and 8 are connected via the connecting pin 22. Therefore, the first rocker arm 7 is driven by the second rocker arm 8, and the intake valve 1 is opened and closed at a timing and lift amount depending on the shape of the high-speed cam 5.

In such a valve train, the connection switching mechanism 1
0 is a cylindrical portion 1 provided at the base of the second rocker arm 8.
7 and the first locker shaft 6 between the position where it engages with the first locker arm 7 and the position where the engagement is released.
Since it has a connecting pin 22 that moves in a direction parallel to the axis of the valve to switch between connecting and disconnecting, it can be placed near the rocker shaft 6, thereby reducing the valve train load. It becomes possible. Further, since the second rocker shaft 8 is provided with the cylindrical portion 17 at its base, it is pivotally supported by the rocker shaft 6 over a relatively long distance, so that the second rocker shaft 8 can swing in a plane perpendicular to the axis of the rocker shaft 6. can be maintained. Furthermore, the engagement recess 30 is provided at the tip of the cylindrical portion 17 and the side surface of the first rocker arm 7, and is easy to process.

FIGS. 4 and 5 show other embodiments of the present invention, and parts corresponding to those in the previous embodiments are given the same reference numerals.

The case 21 is integrally provided with a plurality of projecting portions 38 projecting outward, and screw members 39 inserted through these projecting portions 38 allow the case 21 to be
is fixed to the side surface of the first rocker arm 7. Therefore, the case 21 operates integrally with the first rocker arm 7.

This embodiment can also provide the same effects as the previous embodiment.

FIG. 6 shows still another embodiment of the present invention, and parts corresponding to each of the embodiments described above are given the same reference numerals.

The second rocker arm 8 is not provided with the cylindrical portion 17, and both rocker arms 7 and 8 are pivotally supported by the rocker shaft 6 with their side surfaces perpendicular to the axis of the rocker shaft 6 slidingly touching each other.

Such first and second rocker arms 7, 8
The connection switching mechanism 10' for switching between connection and disconnection is formed by straddling the opposing side surfaces of both rocker arms 7 and 8, which are opposing surfaces 7a and 8a that are close to each other in their connected state, and An engagement recess 30' that extends along the surfaces 7a and 8a and opens on the inner circumferential surface of both rocker arms 7 and 8, a connection position that engages with the engagement recess 30', and a connection release that releases the engagement. The connecting pin 22' is movable between positions and is supported on a rocker shaft peripheral wall 21' serving as a support. The engagement recess 30' is formed by semicircular notches 28' and 29' provided on the sliding surfaces of both the rocker arms 7 and 8, and is aligned with the axis line along the radial direction of the rocker shaft 6. has.

Further, a bottomed sliding hole 40 corresponding to the engaging recess 30' is bored in the peripheral wall 21' of the rocker shaft 6 as a support, and the connecting pin 22' slides into this sliding hole 40. It is movably fitted and the sliding hole 4
A hydraulic chamber 41 that communicates with the hydraulic pressure supply path 35 is defined between the closed end of the connecting pin 22' and the connecting pin 22'. Moreover, an end plate 42 is fixed to the opening end of the sliding hole 40 so as to be flush with the outer surface of the rocker shaft 6 in order to prevent the connecting pin 22' from escaping from the sliding hole 40. A return spring 24' is compressed between the connecting pin 22' and the connecting pin 22'.

Also in this embodiment, the connection switching mechanism 10' is
Located near the rock shaft 6, the hydraulic chamber 41
When hydraulic pressure is supplied to the hydraulic chamber 41, the connecting pin 22' is engaged with the engagement recess 30' to connect both rocker arms 7 and 8, and when the hydraulic pressure in the hydraulic chamber 41 is released, the connecting pin 22' is slid. It is possible to switch between a state in which the rocker arms 7 and 8 are disengaged by being accommodated in the hole 40, and the same effects as in each of the embodiments described above can be achieved.

In the above embodiments, a valve operating system for an intake valve has been described, but the present invention can also be applied to a valve operating system for an exhaust valve.

C. Effects of the Invention As described above, according to the present invention, the connection switching mechanism is formed so as to straddle the facing surfaces of adjacent cam followers that face each other in the connected state and extend along the opposing surfaces. an engagement recess, a support disposed separately from each cam follower, a connecting position disposed along the opposing surface and engaged with the engagement recess, and a connection position separated from the engagement recess and housed in the support. Since the connecting pin is movable along the opposing surface between the connecting pin and the connecting release position, when the connecting pin is in the connecting position, the pin is moved from both cam followers that are about to swing relative to each other. Since the pin is subjected to a shearing force in the direction of vertically dividing the pin, and is not subjected to a bending force in the longitudinal direction, the pin can be made as short, lightweight and compact as possible while maintaining the necessary strength. This can also contribute to downsizing the connection switching mechanism and improving responsiveness during switching.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a cross-sectional plan view and a sectional view taken along the - line in FIG. 3 is a sectional view taken along the line -- in FIG. 1, FIGS. 4 and 5 show other embodiments of the present invention, and FIG. 4 is a cross-sectional plan view corresponding to FIG. 5 is a sectional view taken along the line -- in FIG. 4, and FIG. 6 is a cross-sectional plan view corresponding to FIG. 4 of still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Intake valve, 2... Camshaft, 6... Locker shaft as a support shaft, 7, 8... Locker arm as a cam follower, 7a, 8a... Opposing surface, 10,
10'... Connection switching mechanism, 21... Case as support, 22, 22'... Connection pin.

Claims (1)

[Claims] 1 A plurality of cam followers 7 and 8 including a cam follower 7 interlocked and connected to the intake valve 1 or the exhaust valve
The cam followers 7 and 8 are commonly supported on the support shaft 6 and are arranged adjacent to each other so as to enable rotational movement in mutually different manners according to the rotation of the camshaft 2. In a valve train for an internal combustion engine, in which a connection switching mechanism 10, 10' is provided, the connection switching mechanism 10, 10'
Engagement recesses 30, 30' are formed so as to straddle opposing surfaces 7a, 8a of mutually adjacent cam followers 7, 8 which are adjacent to each other in the connected state and extend along the opposing surfaces 7a, 8a; Cam follower 7,
support bodies 21, 21' arranged separately from 8; a connecting position disposed along the opposing surfaces 7a, 8a and engaged with the engagement recesses 30, 30';30' and supports 21, 2.
a connecting pin 2 that is movable along the opposing surfaces 7a and 8a between the connecting pin 2 and the connecting release position housed in the connecting pin 1';
2, 22'.