JPH0242108A - Valve mechanism for internal combustion engine - Google Patents

Abstract

PURPOSE:To aim at reduction of a striking sound by making the secondary cam sliding contact with the secondary driving rocker arm which is relatively striked at the time of releasing connection in a device in which a pair of the driving arms and a free rocker arm interposed therebetween are connected capable of being free engaged and disengaged. CONSTITUTION:A valve mechanism for opening-closing driving a pair of intake valves 1a, 1b provided every cylinder has a cam shaft 2, linking with a crank shaft, formed integral with the first - the third cams 5-3, the first, the second driving rocker arms 7, 8 and a free rocker arm 9 pivoted to a rocker shaft 6 and a connection switching mechanism 10 provided between rocker arms 7-9. The connection switching mechanism 10 connects the respective rocker arms 7-9 by supplying pressurized oil to a hydraulic chamber 33, moving connecting pins 28, 29 with resistance to a return spring 31 and fitting to the respective guide holes 37, 38. In this case, the secondary and the third cams 4, 3 are provided to be slided in contact with the secondary and the first driving rocker arms 8, 7 respectively.

Description

Detailed Description of the Invention A0 Object of the Invention (+) Industrial Application Field The present invention relates to a first engine valve that is individually interlocked and connected to a pair of engine valves.
and a second drive rocker arm and a free rocker arm that can be free with respect to the engine valve are supported on the rocker shaft such that the free rocker arm is located between both drive rocker arms, and has a high portion corresponding to the lift amount of the engine valve. a first cam having a first cam and slidingly contacting the free rocker arm; a second cam having a higher part lower than the first cam and slidingly contacting one of the driving rocker arms; and a second cam having a higher part lower than the second cam. A third cam is provided on the camshaft and slidably contacts the other of the two driving rocker arms, and the third cam is slidably fitted to the first driving rocker arm so that the third cam can be fitted to the free rocker arm while the end thereof faces the hydraulic chamber. a first connecting pin having one end abutting the first connecting pin and having the other end fittable to the second driving rocker arm so as to be fitted into the free rocker arm; A valve operating device for an internal combustion engine, wherein the rocker arm is provided with a connection switching mechanism including a restriction pin that is fitted into the second drive rocker arm in contact with the second drive rocker arm, and a return spring that is interposed between the restriction pin and the second drive rocker arm. Regarding.

(2) Prior Art Conventionally, such a valve train has been disclosed in, for example, Japanese Patent Application Laid-Open No. 631002.
It is publicly known from Publication No. 10 and the like.

(3) Problems to be Solved by the Invention By the way, in the above conventional system, each rocker arm is connected by supplying hydraulic pressure to the hydraulic chamber of the connection switching mechanism, and the pair of engine valves are opened and closed by the first cam. By releasing the hydraulic pressure in the hydraulic chamber, the connection of each rocker arm is released, and the pair of engine valves are individually driven to open and close by the second and third cams. The disconnection of the connection switching mechanism is started when each rocker arm comes into sliding contact with the inside of the corresponding cam head. However, the lift operation by the first cam may start again before the connection release operation is completed, and if the connection pin is slightly engaged when the lift by the first cam is resumed, the lift If the connection pin is disengaged due to reasons such as an increase in the force applied to the connection pin during operation, the difference in height between the high portion of the first cam and the high portions of the second and third cams causes both drives to be disengaged. Either one of the rocker arms impacts the corresponding cam, producing a so-called hitting sound.

As a result of research by the present inventor in order to prevent the occurrence of such knocking and noise when the connection switching mechanism is disconnected, it was found that when the hydraulic pressure in the hydraulic chamber is released and the connection switching mechanism is operated to disconnect the connection. , it has been found that the first coupling pin returns slightly earlier than the second coupling pin, for example by 1 ms e ce. In other words, since the surface pressure at the sliding contact area between the first cam and the free rocker arm is higher than at other parts, the width of the free rocker arm is set larger, and the length of the second connecting pin is longer than that of the first connecting pin. , the frictional resistance of the second connecting pin is greater than the frictional resistance of the first connecting pin, which causes a slight delay in the return of the free rocker arm. Therefore, the uncoupling of the free rocker arm and the first driving rocker arm is performed slightly before the uncoupling of the free rocker arm and the second driving rocker arm, and the rate at which the free rocker arm is struck by the corresponding cam at the time of uncoupling is the same as that of the first driving rocker arm. It was found that there were more two-drive rocker arms than first-drive rocker arms.

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 suppresses as much as possible the generation of knocking noise when the connection switching mechanism is disconnected.

B0 Structure of the Invention (1) Means for Solving the Problem The present invention provides a first valve that is individually interlocked and connected to a pair of engine valves.
and a second drive rocker arm and a free rocker arm that can be free with respect to the engine valve are supported on the rocker shaft such that the free rocker arm is located between both drive rocker arms, and has a high portion corresponding to the lift amount of the engine valve. a first cam having a first cam and slidingly contacting the free rocker arm; a second cam having a higher part lower than the first cam and slidingly contacting one of the driving rocker arms; and a second cam having a higher part lower than the second cam. The third part that slides into contact with the other of both drive ports/daka arms
a cam is provided on the camshaft, the first connecting pin is slidably fitted to the first drive rocker arm so that the end thereof faces the hydraulic chamber and can be fitted to the free rocker arm; a second connecting pin that is brought into contact with the free rocker arm and whose other end is fittable to the second driving rocker arm; and a second connecting pin that comes into contact with the other end of the second connecting pin and is fitted into the second driving rocker arm. In the internal combustion engine valve operating system in which the rocker arm is provided with a connection switching mechanism including a regulating pin, a return spring interposed between the regulating pin, a second WJrj, and a working mouth hook arm, the second cam is connected to the second driving rocker arm. The third cam is in sliding contact with the first drive rocker arm.

(2) Effect According to the above configuration, the second cam is in sliding contact with the second drive rocker arm, which is often hit when the connection switching mechanism is disconnected, and the second cam has a height higher than the third cam. Therefore, even if the second drive rocker arm is hit by the second cam, the sound of the hit is suppressed to a low level.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, in FIGS. 1, 2, and 3, an aeration valve 1a as a pair of engine valves provided on the side of the engine body, lb
consists of a first cam 5, a second cam 4, and a third cam 3, which are integrally provided on a camshaft 2 that is rotationally driven from the engine's crankshaft at a reduction ratio of 1/2, and a rocker parallel to the camshaft 2. The first and second drive rocker arms 7.8 and the free rocker arm 9, which are pivotally supported on the shaft 6, and the connection switching mechanism 10 provided between each of the rocker arms 7 to 9 are operated to open and close.

The camshaft 2 is rotatably disposed above the engine body E, and the third cam 3 is located at a position corresponding to one intake valve 1a, and the second cam 4 is located at a position corresponding to the other intake valve ib. The first cam 5 is integrated into the camshaft 2 between the third and second cam 3.4.

The first cam 5 is compatible with high-speed operation of the engine, and has a high portion 5a that protrudes relatively large in the radial direction of the camshaft 2, and a base interior 5b. Also, the second cam 4
This corresponds to low speed operation of the engine, and has a high part 4a whose protrusion amount is smaller than the high part 5a of the first cam 5, and a base interior 4b. Furthermore, the third cam 3 also supports low-speed operation of the engine, and has a high portion 3a and a base interior 3b. It is set smaller than 4a.

The rocker shaft 6 is fixedly arranged below the camshaft 2. The rocker shaft 6 includes a first drive port lever arm 7 that is interlocked and connected to one intake valve 1a, a second drive rocker arm 8 that is interlocked and connected to the other intake valve 1b, and a first and second drive port arm 7 that is interlocked and connected to the other intake valve 1b. Free rocker arms 9 arranged between the capper arms 7, 8 are respectively pivoted adjacent to each other.

A cam slipper 11 that slides on the third cam 3 is provided on the top of the first drive rocker arm 7 , a cam slipper 12 that slides on the second cam 4 is provided on the top of the second drive rocker arm 8 , and a cam slipper 12 that slides on the second cam 4 is provided on the top of the second drive rocker arm 8 . A cam slipper I3 that comes into sliding contact with the first cam 5 is provided at the top.

On the other hand, a flange 14 is provided on the upper part of both the intake valves 1a and lb, and a valve spring 15 is interposed between each of these crocodile parts 14 and the engine body E.
lb is biased by the valve spring 15 in the valve closing direction, that is, upward. Additionally, tappet screws 16 that abut the upper ends of the intake valves 1a and lb are screwed into the tips of the first and second drive rocker arms 78 so as to be able to move forward and backward. A locking nut 17, which can abut on the upper surface of the .8, is screwed in each case.

The free rocker arm 9 slightly extends from the rocker shaft 6 toward both intake valves 1a and lb, and the free rocker arm 9 is connected to the high-speed cam 5 by a lost motion mechanism 18 interposed between the rocker shaft 6 and the engine body E. It is elastically biased in the direction of contact with IH.

The lost motion mechanism 18 includes a bottomed cylindrical guide member 1 that is fitted into the engine body E with its closed end facing the engine body E.
9, a piston 20 that is slidably fitted into the guide member 19 and has a tapered abutting portion 20a that abuts the free rocker arm 9 at the end of the free rocker arm 9; A retaining ring 21 is fitted on the inner surface of the guide member 19 near the opening end, and the piston 20
A first member interposed between the piston 20 and the guide member 19 to urge the free rocker arm 9 into contact with the free rocker arm 9.
and second springs 22 and 23.

A hole 24 is drilled in the engine body E for bottomed installation.
For its installation, the guide member 19 is fitted into the hole 24. A spring chamber 25 is defined between the piston 20 and the guide member 19, and a first spring 22 with a relatively small spring constant is compressed between the retainer 26 housed in the spring chamber 25 and the piston 20. , and a second spring 2 with a relatively large spring constant between the retainer 26 and the closed end of the guide member 19.
3 will be reduced.

A small diameter hole 20b with a bottom is coaxially bored in the inner surface of the closed end of the piston 20, and the first spring 22 having a relatively small spring constant is accommodated in the small diameter hole 20b, thereby preventing the first spring 22 from collapsing. is prevented. Also, the contact portion 2 of the piston 20
In order to prevent the inside of the spring chamber 25 from being pressurized or depressurized during the sliding movement of the piston 20, the spring chamber 2
An air vent hole 27 communicating with the outside of the contact portion 20a is formed in the shape of a cross and opens on the outer surface of the contact portion 20a.

The retaining ring 21 can be held at the base end of the abutting portion 20a of the piston 20, thereby preventing the piston 20 from being pulled out from the guide member 19.

In FIG. 4, a connection switching mechanism 10 is provided between each of the rocker arms 7 to 9 for switching between connection and disconnection. This connection switching mechanism 10 includes a first connection pin 28 that can connect the first drive rocker arm 7 and the free rocker arm 9, a second connection pin 29 that can connect the free rocker arm 9 and the second drive rocker arm 8, and a second connection pin 28 that can connect the first drive rocker arm 7 and the free rocker arm 9. It includes a regulating pin 30 that regulates the movement of the first and second connecting pins 28 and 29, and a return spring 31 that biases each pin 28 to 30 toward the disconnection side.

The first drive rocker arm 7 has a first guide hole 32 with a bottom that is open to the free rocker arm 9 side and is bored parallel to the rocker shaft 6, and the first connecting pin 28 slides into the first guide hole 32. They are movably fitted, and a hydraulic chamber 33 is defined between one end of the first connecting pin 28 and the closed end of the first guide hole 32 .

Moreover, a first connecting pin 28 is provided at the closed end of the first guide hole 32.
A regulating protrusion 34 is provided in a protruding manner to regulate movement toward one end. Further, a communication passage 35 communicating with the hydraulic chamber 33 is bored in the first WA dynamic rocker arm 7, and a hydraulic pressure supply passage 36 communicating with a hydraulic pressure supply source (not shown) is provided in the rocker shaft 6. Regardless of the swinging state of the 1-drive rocker arm 7, it is always in communication with the communication path 34.

In the free rocker arm 9, a guide hole 37 corresponding to the first guide hole 32 is bored parallel to the rocker shaft 6 and extends between both sides, and one end is in contact with the other end of the first connecting pin 28. The second connecting pin 29 is connected to the guide hole 37.
is slidably fitted to.

In the second drive rocker arm 8, a second guide hole 38 with a bottom corresponding to the guide hole 37 is opened to the free unloader arm 9 side and is bored parallel to the rocker shaft 6. A bottomed cylindrical regulation pin 30 that abuts the other end is slidably fitted into the second guide hole 38 . This regulation pin 30 is arranged with its open end facing the closed end side of the second guide hole 38, and the flange portion 30a extending radially outward at the open end is aligned with the second guide hole 38. sliding into contact with. The return spring 31 is compressed between the closed end of the second guide hole 38 and the closed end of the regulating pin 30, and the spring force of the return spring 31 causes the pins 28, 29, 30 to come into contact with each other. is urged toward the hydraulic chamber 33 side. Furthermore, a communication hole 39 for removing air and oil is bored at the closed end of the second guide hole 38.

Further, a retaining ring 4o that can be engaged with the alligator portion 30a of the regulating pin 30 is fitted into the inner surface of the second guide hole 38, and the retaining ring 40 prevents the regulating pin 30 from being removed from the second guide hole 38. Output is blocked.

Moreover, the fitting position of the retaining ring 40 is such that the restriction pin 30 is moved further toward the free rocker arm 9 from the state where it is in contact with the second connecting pin 29 at a position corresponding to between the free rocker arm 9 and the second drive rocker arm 8. is set to prevent

The free rocker arm 9 is provided with recesses 41 and 42, respectively, on the sides facing the first and second drive rocker arms 7.8 by cutting out the weight for weight reduction.
Four parts 41.4 of the first and second drive rocker arms 7.8
Spring pins 43 and 44, which enter into the recesses 41 and 42, are press-fitted and fixed on the side surface facing 2. These recesses 41.42 and spring pins 43, 44 restrict the amount of relative movement between the free rocker arm 9 and the first and second drive rocker arms 7.8, but the first drive rocker arm slidingly contacts the third cam 3. 7 and the second drive rocker arm 8 which is in sliding contact with the second cam 4, and the free rocker arm 9 which is in sliding contact with the first cam 5, swing relative to each other in the operating state. and the second
It is formed to a size that does not impede the relative rocking of the drive rocker arm 7.8 and the free rocker arm 9 during the operation.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, the hydraulic pressure in the hydraulic chamber 33 is released in the connection switching mechanism 10, and each pin 28 and 30 is connected to the return spring 31.
It is in a disconnected state in which it has moved to the maximum extent towards the hydraulic chamber 33 due to the spring force. In this state, the first and second connecting pins 2
The contact surface of 8.29 is located at a position corresponding to between the first drive rocker arm 7 and the free rocker arm 9, and the contact surface of the second connecting pin 29 and the restriction pin 30 is located between the free rocker arm 9.
and the second drive rocker arm 8. Therefore, each rocker arm 7-9 is in a state in which relative angular displacement is possible with respect to each other.

In this disconnected state, the first drive rocker arm 7 slides into contact with the third cam 3 due to the rotation of the camshaft 2, and the second drive rocker arm 8 slides into contact with the second cam 4.
Accordingly, one intake valve 1a swings in response to sliding contact with the
is the timing and lift amount shown by curve 3C in FIG. 5 according to the shape of the third cam 3, and the timing and lift amount shown by curve 4C in FIG. It opens and closes depending on the lift amount. At this time, the free rocker arm 9 swings in accordance with the sliding contact with the first cam 5;
The rocking motion of the first and second drive rocker arms 7.8
It has no effect on

High hydraulic pressure is supplied to the hydraulic chamber 33 when the engine is operating at high speed. As a result, the first and second connecting pins 28, 29 and the regulating pin 30 move toward the connecting position against the spring force of the return spring 31, and the first connecting pin 28 fits into the guide hole 37 and The two connecting pins 29 fit into the second guide holes 38, and the rocker arms 7 to 9 are connected. At this time, since the amount of swing of the free rocker arm 9 in sliding contact with the first cam 5 is the largest, the first and second driving rocker arms 7
．． 8 swings together with the free rocker arm 9, and both intake valves 1
a and lb correspond to the curve 5C in FIG. 5 depending on the shape of the first cam 5.
The opening/closing operation is performed at the timing and lift amount shown in .

During this connection operation, the axes of the first guide hole 32, guide hole 37, and second guide hole 38 may not completely coincide with each other due to manufacturing tolerances of the rocker arms 7 to 9. However, when the free rocker arm 9 is in sliding contact with the base interior 5b of the first cam 5, the second spring 23 in the lost motion mechanism 18 is in a free length state, and there is a gap between the piston 20 and the retainer 26. Therefore, it is possible to slightly swing the free rocker arm 9 while contracting the first spring 22 whose spring constant is set to be relatively small, and the free rocker arm 9 is moved at the tip of the first connecting pin 28.
The axes can be perfectly aligned by pushing down or up slightly.

Further, during the above-mentioned high-speed operation, since both intake valves 1a and lb are driven to open and close by the free rocker arm 9, it is necessary to ensure that the cam slipper 13 of the free rocker arm 9 slides into contact with the ml cam 5, and the lost motion mechanism 18 is a relatively strong spring force that moves the free rocker arm 9 to the camshaft 2.
You need to press it to the side. Therefore, the high part 5 of the first cam 5
When a comes into sliding contact with the cam slipper 13, the first spring 22, which has a relatively small spring constant, is contracted until the piston 20 comes into contact with the retainer 26, and the piston 2
0 is biased toward the first cam 5 by a second spring 23 with a relatively large spring constant.

Therefore, the free rocker arm 9 is in sliding contact with the first cam 5 with a relatively large spring force, and a high lift load can be obtained.

When the operating state of the engine changes from high-speed operation to low-speed operation, the hydraulic pressure in the hydraulic chamber 33 in the connection switching mechanism 10 is released. In response to this oil pressure release, the second connecting pin 29 and the first connecting pin 2 are urged toward the first drive rocker arm 7 by being pushed by the regulating pin 30 by the spring force of the return spring 31. When the free rocker arm 9 is in sliding contact with the high portion 5a of the first cam 5, a force is applied to the first connecting pin 28 and the second connecting pin 29 in a direction perpendicular to their axes. , the frictional force between the first guide hole 32, the guide hole 37, and the second guide hole 38 is large, and the first and second connecting pins 28 and 29 do not move.

When the first cam 50 base interior 5b comes into sliding contact with the free rocker arm 9, the first and second connecting pins 28.2
Since no force in the direction perpendicular to the axis as described above acts on the pin 9, the first connecting pin 28 returns to the first guide hole 32, and the second connecting pin 29 returns to the guide hole 37. However,
The cam slipper 13 of the free rocker arm 9 is set to have a longer length along the axial direction of the camshaft 2 than the other cam slippers 11 and 12 in order to withstand a large lift load. 9 along the camshaft 2 is greater than that of the first and second drive rocker arms 7.8, so that the length along the axis of the second coupling pin 29 is greater than that of the first coupling pin 28. As a result, the sliding resistance of the second connecting pin 29 is greater than that of the first connecting pin 28, and due to inertia, the first connecting pin 28 moves faster than the second connecting pin 29 completely returns into the guide hole 37. It returns to the first guide hole 32 only by, for example, 1 m5ec earlier.

As a result of the above, when the connection switching mechanism 10 is disconnected, the connection between the free rocker arm 9 and the first drive rocker arm 7 is disconnected before the connection between the free rocker arm 9 and the second drive rocker arm 8 is disconnected. For this reason, the inside of the base 3b, 4b, 5b of each cam 3, 4°5
The disconnection of the connection switching mechanism 10 is not completed while the corresponding rocker arm 7.8.9 is in sliding contact, and for some reason, the connection is disconnected during the lift operation by the high portion 5a of the first cam 5. The ratio is greater between the free rocker arm 9 and the second driving rocker arm 8 than between the free rocker arm 9 and the first driving rocker arm 7. Moreover, if the connection occurs during such lift operation,
The first and second drive port hook arms 7.8 are struck by the corresponding cams 3, 4, and the second drive rocker arm 8, which is often struck, is in sliding contact with the second cam 4, and the first cam The lift difference di (see FIG. 5) between the high position portion 5a of the first cam 5 and the high position portion 4a of the second cam 4 is
is smaller than the lift difference d2 (see FIG. 5) between the upper part 3a of the third cam 3 and the second drive rocker arm 8.
Even if it is hit by the second cam 4, the sound of the hit is small.

In the above embodiments, the valve operating system for the intake valves 1a and 1b has been described, but the present invention is also applicable to the valve operating system for the exhaust valves.

C0 Effects of the Invention As described above, according to the present invention, the second cam is in sliding contact with the second drive rocker arm, and the third cam is in sliding contact with the first drive rocker arm, so that there is no impact when the connection switching mechanism is disconnected. The second cam is in sliding contact with the second drive rocker arm, which has a high proportion of Even if the rocker arm is hit by the second cam, the sound of the hit can be suppressed to a low level.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a plan view, FIG. 2 is a sectional view taken along line n-n1 in FIG.
Figure III-I
The rV line sectional view and FIG. 5 are valve lift characteristic diagrams. la, lb...Intake valve, 2...Camshaft, 3...
...Third cam, 3a, 4a, 5a...High part, 4...
- Second cam, 5... First cam, 6... Rocker shaft, 7... First drive rocker arm, 8... Second drive rocker arm, 9... Free rocker arm, 10...
Connection switching mechanism, 28...First connection pin, 29...Second connection pin, 30...Restriction pin, 31...Return spring Patent applicant Honda Motor Co., Ltd. agent Bu Ochiai, Physician Kendo 1) Hide Naka Takashi Figure 2 Figure 1

Claims (1)

[Claims] The first and second valves are individually interlocked and connected to a pair of engine valves.
A drive rocker arm and a free rocker arm that can be free with respect to the engine valve are supported on the rocker shaft with the free rocker arm positioned between both drive rocker arms, and have an elevated portion corresponding to the lift amount of the engine valve. a first cam that slides in contact with the free rocker arm; a second cam that has an elevated portion that is lower than the first cam and that slides into contact with either one of the driving rocker arms; a third cam in sliding contact with the other drive rocker arm; the camshaft is provided with a third cam that is slidably fitted in the first drive rocker arm with one end facing the hydraulic chamber and capable of being fitted into the free rocker arm; a connecting pin; and a second connecting pin that is fitted into the free rocker arm with one end abutting the first connecting pin and the other end being fittable with the second driving rocker arm.
A connection switching mechanism includes a connection pin, a restriction pin that abuts the other end of the second connection pin and is fitted into the second drive rocker arm, and a return spring interposed between the restriction pin and the second drive rocker arm, In the valve operating system for an internal combustion engine provided on the rocker arm, the second cam is in sliding contact with the second driving rocker arm, and the third cam is in sliding contact with the first driving rocker arm. .