JPH0533621A - Valve gear for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide improved manufacturing efficiency and cost reduction by relieving positional accuracy between a locking part and an engagement part in manufacturing with the constantly smooth connecting action of both rocker arms ensured. CONSTITUTION:This valve gear is provided with the first rocker arm 1 whose tip comes into contact with an air intake valve, the second rocker arm 2 which is supported at the side part of the first rocker arm 1 so that it may oscillate relatively, cams 13, 14 for low and high speed which comes into contact with the respective first and second rocker arms 1, 2 and have different lifting amount from each other, and a connection/disconnection means 33 which connects and disconnects the rocker arms 1, 2 according to the operating conditions of an engine. Moreover, the locking part of the second rocker arm 2 which is arranged facing the extending part 38 of the first rocker arm 1 and presses a disc 36 as necessary is provided with a protrusion part 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system for an internal combustion engine, and more particularly to a valve operating system capable of switching valve lift characteristics during low engine speed and high engine speed.

[0002]

2. Description of the Related Art Conventionally, the lift characteristic of an intake valve or an exhaust valve is made different according to the operating state for the purpose of achieving both torque during low-medium speed operation and improvement of output during high-speed operation. Alternatively, it is known to control the intake / exhaust amount (see, for example, JP-A-63-167016 and JP-A-63-57805).

Explaining this, a rocker shaft for low speed, whose rocking tip abuts on the valve, and a rocker shaft for high speed, which is adjacent to one side of the rocker arm for low speed and has no contact portion with the valve, are common. The low-speed rocker arm has a low-speed cam rolling on it, and the high-speed rocker arm has a high-speed cam rolling on the high-speed rocker arm that has a profile such that the valve opening angle or valve lift is larger than that of the low-speed cam. ..

Further, connection releasing means arranged in parallel with the rocker shaft are provided on opposite sides of the low-speed and high-speed rocker arms. The connection releasing means includes guide holes concentrically formed in opposite side portions of both rocker arms, and a relatively long plunger slidably accommodated in the guide holes. In response to the operating oil pressure and the spring force of the coil spring, the two rocker arms are engaged with each other by engaging them over the guide holes, or the rocker arms for high speed are released from the guide holes to release the connected state. ing.

[0005]

However, in the above-mentioned conventional apparatus, since a plurality of rocker arms per cylinder are supported by a common rocker shaft, there are errors in machining accuracy of the rocker arms and the rocker arms. There is a possibility that variations in dimensional accuracy may occur between both rocker arms due to an assembly error or the like when assembled on the shaft.
Therefore, the relative axial center of each guide hole is displaced, and the tip edge of the plunger abuts against the hole edge of the guide hole of the high speed rocker arm when the both rocker arms are connected, so that the two rocker arms can be smoothly connected. In addition to being hindered, there is a possibility that the connecting action may become impossible if the positional deviation of the guide hole is large. In addition, the opening and closing characteristics of the valve are likely to vary due to the positional deviation of the guide holes.

As a result, when manufacturing each rocker arm, a high positional accuracy of both guide holes is required, which inevitably results in a decrease in manufacturing work efficiency and a rise in cost.

The present invention has been devised in view of the above-mentioned problems of the prior art, and aims at relaxing the positional accuracy of the engaging portion and the engaging portion while ensuring a smooth connecting action of both rocker arms, and performing a manufacturing operation. The objective is to improve efficiency and reduce costs.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a first rocker arm having a base end portion swingably supported via a main rocker shaft and a tip end portion abutting an intake valve or an exhaust valve, and the first rocker arm. A second rocker arm supported on the side of the rocker arm so as to be able to swing relative to each other, a plurality of cams that rotate in synchronization with the crankshaft of the engine, and are in sliding contact with the first rocker arm and the second rocker arm, and have different lift amounts, respectively, and engine operation. Depending on the state, a coupling release means for engaging or disengaging an engaging member and an engaging member respectively provided on opposite side portions of each rocker arm to connect or disconnect the both rocker arms. In the valve device, the locking portion of the rocker arm on the one side is formed in a protrusion shape at a position where the engaging member is pressed.

[0009]

According to the present invention having the above-described structure, the locking portion of the rocker arm on one side is formed not by the cylindrical hole (guide hole) but by the projection portion. Since it is possible to absorb an error, an assembly error, and the like, high positional accuracy with respect to the engaging portion on the other side facing each other is not required, and the positional accuracy is relaxed. As a result, the manufacturing work is facilitated and the cost is reduced.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. In this embodiment, two valves having the same function for one cylinder (either intake valve or exhaust valve,
The illustrated one is applied to an internal combustion engine having an intake valve).

That is, FIGS. 1 to 6 show a first embodiment of the present invention, in which each cylinder is provided with a single first rocker arm 1 corresponding to two intake valves 3 and 3. The first rocker arm 1 has a base end portion 1a swingably supported by a cylinder head via a first rocker shaft 4 common to each cylinder, while a tip end portion 1b has a hydraulic lash adjuster 5 ,.
It is in contact with the tops of the stems 3a, 3a of the intake valves 3, 3 via 5. The first rocker arm 1 has a substantially rectangular shape in plan view as shown in FIGS. 3, 7, and 8, and a rectangular opening 6 is cut out in the longitudinal direction orthogonal to the rocker shaft 4 on one side. At the same time, a pair of boss portions 7, 7 are provided on the upper portion of the other side on the rocker shaft 4 side. The support shaft 8 has a needle bearing 9 in the opening 6.
While the roller 10 is rotatably provided via
Between the boss portions 7 and 7, a second rocker shaft 11 whose both ends are press-fitted into support holes 7a and 7a formed through the boss portions 7 and 7, and the rocker shaft 11 is swingably supported. The second rocker arm 2 is provided. Further, the roller 10 is in contact with a low speed cam 13 provided on a cam shaft 12 that rotates in synchronization with a crank shaft (not shown).

As shown in FIGS. 4, 9, and 10, the second rocker arm 2 has a base end 2a supported by a first rocker arm 1 via a second rocker shaft 11 so as to be relatively swingable. At the same time, a cam follower portion 15 that does not have a portion that comes into contact with the intake valve 3 and that is in sliding contact with the high speed cam 14 that is juxtaposed with the low speed cam 13 is formed in a circular arc shape while the lower portion thereof is formed. The cam follower portion 15 is provided on one end side of the lower portion 17 of the narrow portion 16 on the side.
The convex portion 19 that comes into contact with the lost motion mechanism 18 that is pressed against is integrally provided.

The lost motion mechanism 18 is provided in a holding hole 20 provided on the lower end side of the other side of the first rocker arm 1, and the upper surface of the convex portion 1 is slidable while sliding in the holding hole 20.
And a pressing portion 21 having a cylindrical shape with a lid, which abuts on 9, and the pressing portion 21.
The lost motion spring 22 for urging the lower end of the holding hole 20 through a support ring 23 to support the lower end of the lost motion spring 22. There is.

The hydraulic lash adjusters 5 and 5 are also provided.
Is a tip portion 1 of the first rocker arm 1 as shown in FIG.
A cylindrical plunger 26 having a bottom, which is provided so as to be able to move forward and backward through sliding holes 25 provided at the lower portions of both sides of b, and a high pressure chamber 28 and a reservoir chamber which are provided inside the plunger 26 and through a partition wall 27a. A cylindrical portion 27 separated by 29
And a check valve 31 provided in the high pressure chamber 28 to close the communication hole 30 at the center of the partition wall 27a. When the intake valves 3 and 3 move up and down (open and close) by the swinging force of the first rocker arms 1 and 1 and the spring force of the valve springs 3b and 3b, a gap is generated between the plunger 26 and the top of the stem 3a. At the same time try to tip 1
b The hydraulic pressure in the reservoir chamber 29 introduced through the oil sump chamber 31 and the oil passages 32, 32 in the center is supplied from the communication hole 30 into the high pressure chamber 28 to push out the plunger 26, so that the stem 3a is constantly connected to the top. It is designed to make zero rush adjustment.

Further, the first and second rocker arms 1, 2
Are connected or released by the connection releasing means 33 according to the engine operating state. The connection releasing means 33 is configured as shown in FIGS. 1 and 2. That is, the bottomed cylindrical guide hole 34 is formed in the wall portion 1c of the first rocker arm 1 on the side of the roller 10.
A cylindrical short piston 35 formed in parallel with the rocker shaft 4 and a disc 36, which is an engaging member having a smaller diameter than the piston 35, are slidably held in the piston, and is located behind the piston 22. The oil chamber 37 is defined. As shown in FIGS. 1 and 2, the wall portion 1c is formed by cutting out an opening end portion of the guide hole 34 on the side of the first rocker shaft 4 and forming an extending portion 38 as an engaging portion on the opposite side. ing. On the other hand, on the one end side of the lower portion 17 of the second rocker arm 2, a cylinder hole 3 coaxial with the guide hole 34 and having the same diameter is provided.
9 is formed, and the piston 35 is inserted into the cylinder hole 39 by the spring force of the return spring 40.
A plunger 41 that biases in seven directions is stored.

Then, the guide hole 34 and the cylinder hole 3
9, a protrusion 42 serving as a locking portion is integrally provided on the other end side of the lower portion 17 of the second rocker arm 2.
More specifically, this protrusion 42 is
As also shown in FIG. 5, a part of the other end of the lower portion 17 of the second rocker arm 2 is cut out to expose the lower surface half of the narrow width portion 16 to form a protruding shape. A lower surface 42a of the protrusion 42 is formed in an arc surface shape having a radius of curvature slightly larger than that of the outer peripheral surface of the disk 36.

A working hydraulic pressure is introduced into the oil chamber 37 by a hydraulic circuit.
As shown in FIG. 5, the hydraulic passage 44 in the tube 43 inserted into the internal axial hole 4a of the first rocker shaft 4,
A communication passage 46 formed in the first rocker arm 1 to connect the radial hole 45 of the first rocker shaft 4 and the oil chamber 37.
It consists of and. The hydraulic pressure discharged from the oil pump is introduced into the hydraulic passage 44 through a switching valve (not shown) during a predetermined high speed operation. A control unit for electronically controlling the operation of the switching valve inputs an engine rotation signal, a cooling water temperature signal, a lubricating oil temperature signal, an intake supercharging pressure signal by a supercharger, a throttle valve opening signal, and the like. Based on these detected values, the rapid change of the engine torque is suppressed and the switching between the low speed cam 13 and the high speed cam 14 described later is smoothly performed.

The low speed cam 13 and the high speed cam 14 adjacent to the low speed cam 13 are integrally formed on a common cam shaft 12 so as to satisfy the valve lift characteristics required at low engine speed and high engine speed. They are formed in different shapes (including similar shapes having different sizes). That is, the high-speed cam 14 has a profile that makes at least one of the valve lift amount and the valve opening period larger than the low-speed cam 13. Here, the valve lift amount and the valve opening period are both increased.

Therefore, according to this embodiment, when the engine is operating at low speed, the switching valve closes the hydraulic passage 44 based on the control signal from the control unit.
The supply of hydraulic pressure to 7 is cut off. Therefore, plunger 4
2, the spring force of the return spring 40 causes the piston 35 and the disk 36 to be housed in the guide hole 34, and the plunger 41
It is also held in the cylinder hole 39. Therefore, the rocker arms 1 and 2 are not connected to each other and swing independently,
The first rocker arm 1 swings according to the profile of the low speed cam 13, and opens and closes the intake valves 3 and 3 via the hydraulic lash adjusters 5 and 5. On the other hand, the second rocker arm 2 oscillates according to the profile of the high-speed cam 14, but at this time, only the tip end surface of the disk 36 and the tip end surface of the plunger 41 are in sliding contact with each other. It does not hinder the movement of the rocker arm 1.

On the other hand, when the engine shifts to the high speed operation range, when the hydraulic passage 44 is opened by the switching valve and the operating hydraulic pressure is introduced from the hydraulic passage 44 into the oil chamber 37 through the communication passage 46, the piston 35 and the disk 36 move against the spring force of the return spring 40 to move the plunger 41.
Is pushed back to the bottom of the cylinder hole 39. Therefore, the disk 36 engages in a sandwiched manner between the protrusion 42 and the extension 38 as shown in FIG. As a result, the first rocker arm 1 and the second rocker arm 2 are connected to each other, and
When the rocker arm 2 swings according to the profile of the high-speed cam 14, the lift force is transmitted from the protrusion 42 to the extension 38 via the disc 36, and the first rocker arm 1 and the second rocker arm 2 are shaken together. To move.
That is, when the first rocker arm 1 and the second rocker arm 2 are integrally rocked, the roller 10 moves the low speed cam 13
Then, the intake valves 3 and 3 are opened and closed according to the profile of the high speed cam 14, and the valve opening angle and the lift amount are increased.

As described above, in this embodiment, since the engaging portion of the second rocker arm 2 is formed by the protrusion 42 instead of the guide hole, even if there is an error in the processing accuracy of the component parts such as the rocker arms 1, 2 or the assembling. Even if an error or the like occurs, the protrusion 42 can absorb the positional deviation from the guide hole 34 due to the error. Therefore, both rocker arms 1,
Of course, the smooth connecting action of 2 is always ensured, and the projection 42 and the guide hole 34 of the first rocker arm 1 are also provided.
Further, the high positional accuracy with respect to the extension portion 38 is not required, and it is sufficiently relaxed. Therefore, the manufacturing work of the rocker arms 1 and 2 can be facilitated and the manufacturing cost can be reduced.

Further, since the second rocker arm 2 is connected to the first rocker arm via the second rocker shaft 11, compared to the conventional structure in which both rocker arms are fitted to a common rocker shaft, 2 The rocker arm 2 can be greatly downsized.

As a result, the inertial mass of the valve train is reduced and the followability of the intake valves 3 and 3 in the high rotation range is improved. Also,
Due to the downsizing of the second rocker arm 2, the urging force of the lost motion spring 22 can be reduced, and the friction between the second rocker arm 2 and the high speed cam 14 can be reduced.
This can reduce fuel consumption.

Further, in this embodiment, the guide hole 34 is partially cut out so that the disk 36 is held by the extending portion 38 and the protrusion 42, so that the piston is engaged with each guide hole as in the conventional case. In this case, the piston is prevented from tilting and both edges thereof are pressed against the inner surface of the guide hole to cause so-called prying. Therefore, in order to prevent such twisting, it is not necessary to lengthen the piston as in the conventional case, so that the width of each rocker arm 1, 2 can be shortened and the miniaturization of the device is promoted.

Further, the protrusion 42 of the second rocker arm 2
It is also possible to form the lower surface 42a into a flat shape by replacing it with an arc surface as shown in FIG.

Further, the disc 36 has an outer diameter shown in FIG.
It is also possible to make the outer diameter of the piston 35 larger than that of the piston 35 as shown in FIG. 4, and the relative diameter of the roller 10 and the cam follower portion 15 with respect to the cams 13 and 14 can be selected by freely selecting the outer diameter of the disk 36. Height can be adjusted. Therefore, it is possible to further relax the positional accuracy of the protrusion 42 of the second rocker arm 2, the guide hole 34, and the extension 38.

Further, in the present embodiment, the boss portions 7, 7 for supporting the second rocker arm 2 via the second rocker shaft 11 are integrally provided like the first rocker arm 1, so that the boss portion is formed. The manufacturing work of 7, 7 is easy, and since the second rocker arm 2 can be assembled from the outside of the first rocker arm 1, the assembling work is also easy.

As shown in FIG. 13, the disc 36 is eliminated and the extended piston 35 causes the protrusion 42
It is also possible to engage with the guide hole 34.

[0029]

As is apparent from the above description, according to the present invention, the locking portion of the rocker arm on one side is formed in a projecting shape at a position for pressing the engaging member. Even if an error occurs in machining accuracy of a component, an assembly error, or the like, the protrusion can absorb the positional deviation from the engaging portion on the other side due to the error. Therefore,
Of course, the connecting action of both rocker arms can always be performed smoothly, and high positional accuracy with the engaging portion on the other side is not required, and the rocker arms are sufficiently relaxed. As a result, the rocker arm can be easily manufactured and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 3 showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 3 showing the operation of this embodiment.

FIG. 3 is a plan view of this embodiment.

FIG. 4 is a sectional view taken along line BB of FIG.

5 is a sectional view taken along the line CC of FIG.

6 is a cross-sectional view taken along line DD of FIG.

FIG. 7 is a plan view showing a first rocker arm used in this embodiment.

FIG. 8 is a side view of the first rocker arm.

FIG. 9 is a plan view showing a second rocker arm used in this embodiment.

FIG. 10 is a front view of the second rocker arm.

FIG. 11 is a side view showing another example of the second rocker arm.

FIG. 12 is a cross-sectional view of essential parts showing a second embodiment of the present invention.

FIG. 13 is a cross-sectional view of essential parts showing a third embodiment of the present invention.

[Explanation of symbols]

1 ... 1st rocker arm, 1a ... Base end part, 1b ... Tip part,
2 ... 2nd rocker arm, 3 ... Intake valve, 4 ... 1st rocker shaft, 13, 14 ... Low speed / high speed cam, 33 ... Decoupling means, 36 ... Disc (engaging member), 38 ... Extension part ( Engagement portion), 42 ... Projection portion (locking portion).

Claims (1)

Claim: What is claimed is: 1. A first rocker arm, the base end of which is swingably supported via a first rocker shaft, and the tip of which abuts an intake valve or an exhaust valve, and the first rocker arm. A second rocker arm that is supported on the side of the engine so as to be able to swing relative to each other; In accordance with the above, the moving part is provided with a coupling releasing means for engaging or disengaging the engaging member and the engaging portion respectively provided on the opposite side portions of the rocker arms to connect or disconnect the both rocker arms. In the valve device, the locking portion of the rocker arm on the one side is formed in a protruding shape at a position for pressing the engaging member, and a valve operating device for an internal combustion engine.