JPH0530403U - Valve drive for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] In switching the valve lift characteristics by connecting or disconnecting the sub-rocker arm 7 to the main rocker arm 1, the sliding contact portion between the sub-rocker arm 7 and the cam 14 is reliably lubricated. [Structure] The sub-rocker arm 7 is supported by a sub-rocker shaft 8 on the main rocker arm 1, and both can be hydraulically connected. At the rocking end of the main rocker arm 1,
A pair of hydraulic lash adjusters 31 are arranged, and lubricating oil is supplied from the rocker shaft 2 through an oil passage 37. The oil passage 37 communicates with the lubricating oil passage 40 in the sub rocker shaft 8, and a splash hole 42 is provided toward the cam sliding contact portion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a valve drive device for an internal combustion engine in which a valve lift characteristic can be switched by selectively using cams having different profiles.

[0002]

[Prior Art]

 A valve drive system for an internal combustion engine generally has a structure in which a cam lift is transmitted to an intake valve and an exhaust valve via a rocker arm and a swing arm, and an intake valve and an exhaust valve that are biased in a closing direction by a valve spring are pushed open. However, preferable valve lift characteristics differ in the low speed range and high speed range of the engine, or in the low load range and the high load range of the engine, for example. Therefore, the valve drive device can be switched depending on the operating conditions. Have been proposed.

As an example, in Japanese Patent Laid-Open No. 63-106309 and Japanese Utility Model Laid-Open No. 64-22802, for example, two types of cams having different profiles are provided side by side and driven by each of them. A structure is known in which the rocker arm and the sub-rocker arm are switched to a connected state or a detached state as needed. That is, in the above valve drive device, one end of the main rocker arm is swingably supported by the rocker shaft, and the adjusting screw provided at the other swing end faces the valve stem end of the intake / exhaust valve. .. An auxiliary rocker arm is swingably arranged adjacent to the main rocker arm, but the auxiliary rocker arm is not directly connected to the intake and exhaust valves. Further, on the camshafts located above these rocker arms, a first cam with a small valve lift amount that presses the main rocker arm and a second cam with a large valve lift amount that presses the sub rocker arm are formed side by side. .. Both rocker arms can be connected as needed by a connecting mechanism using hydraulic pressure.

Therefore, in the state where the main and sub rocker arms are separated, the main rocker arm swings following the first cam, whereby the intake and exhaust valves are opened and closed. Further, when the main and auxiliary rocker arms are connected, the intake / exhaust valve is opened / closed as the auxiliary rocker arm driven by the second cam swings.

In Japanese Utility Model Application Laid-Open No. 64-22802, a pipe for a lubricating oil passage is provided above the cam shaft to lubricate the sliding contact portion between the rocker arm and the cam. A configuration in which the lubricating oil is sprayed is shown.

Although not a valve drive device of a valve lift characteristic switching type, a configuration in which a small hydraulic lash adjuster is arranged at the rocking end of a rocker arm is disclosed, for example, in Japanese Utility Model Laid-Open No. 63-73506. .. The rocker arm has a central portion swingably supported by a rocker shaft, and is configured to transmit the lift of the cam that abuts the cam follower portion at one end to the intake and exhaust valves via the lash adjuster at the other end. ing. A reservoir chamber for supplying oil to the lash adjuster is provided at the upper part of the lash adjuster, and the air mixed in the lubricating oil is separated and discharged. In addition to the oil supply system for the lash adjuster, an oil splash hole for lubricating the cam slide contact part is formed in the center of the rocker arm.

[0007]

[Problems to be solved by the device]

 In the valve drive device of the valve lift characteristic switching type as described above, since the layout is such that the camshaft is arranged above the rocker arm, the lubricating oil passage is formed above the camshaft as in Japanese Utility Model Laid-Open No. Sho 64-22802. If the piping for the cylinder is provided, the total height of the cylinder head becomes high, and it is difficult to spray the lubricating oil directly on the sliding contact portion between the cam and the rocker arm.

Further, if the main rocker arm is provided with a lash adjuster, it is difficult to secure a sufficiently large reservoir chamber for separating and discharging air at the top of the oil supply system due to the positional relationship with the cam shaft. However, there is also a problem that air easily mixes into the lash adjuster side.

[0009]

[Means for Solving the Problems]

 Therefore, in this invention, the lubricating oil is guided upward from the oil supply system to the lash adjuster and is ejected toward the sliding contact portion between the sub rocker arm and the cam. That is, a valve drive device for an internal combustion engine according to the present invention has a main rocker arm, one end of which is rockably supported by a rocker shaft and which rocks by being driven by a cam of a cam shaft located above the main rocker arm. The sub-rocker shaft mounted on the upper part of the base end of the sub-rocker shaft, the sub-rocker shaft whose one end is swingably supported by the sub-rocker shaft, and the sub-rocker arm that is swung by another cam of the cam shaft, and the main rocker shaft. A hydraulic lash adjuster arranged at the swinging end of the cam arm, a valve that is driven to open and close by the main rocker arm via the hydraulic lash adjuster, and a connection mechanism that hydraulically connects the sub rocker arm and the main rocker arm. , The oil passage for the lash adjuster from the lubricating oil passage in the rocker shaft to the hydraulic lash adjuster. A communication passage that guides the lubricating oil from the oil passage for the lash adjuster to the lubricating oil passage in the upper sub-rocker shaft, and a splash hole penetrating the bearing portion of the sub-rocker arm toward the sliding contact portion between the sub-rocker arm and the cam. And a communication port formed in the sub-rocker shaft so that the splash hole and the lubricating oil passage in the sub-rocker shaft are always communicated with each other.

[0010]

[Action]

 The lubricating oil required to operate the lash adjuster is supplied from the lubricating oil passage in the rocker shaft through the oil passage for the lash adjuster in the main rocker arm. Then, a part of it is guided to the lubricating oil passage in the upper sub-rocker shaft, and is jetted toward the sliding portion between the sub-rocker arm and the cam through the communication port and the splash hole of the sub-rocker shaft. Here, since the air contained in the lubricating oil tends to move upward, it gathers in the lubricating oil passage in the sub rocker shaft and is discharged to the outside together with the lubricating oil ejected from the splash hole.

[0011]

【Example】

 An embodiment of the present invention will be described below in detail with reference to FIGS.

As shown in FIGS. 1 and 5, the main rocker arm 1 has a wide rectangular shape when viewed from above, and one end of the main rocker arm 1 is swingably supported by the rocker shaft 2. The main rocker arm 1 has a frame-like shape in which a substantially rectangular opening 3 is offset to one side, and a roller cam follower 4 is provided at a position offset to the side opposite to the opening 3. There is. As shown in FIG. 5, the roller cam follower 4 is rotatably supported by a cam follower shaft 5 via a roller bearing 6.

A small sub-rocker arm 7, which is substantially rectangular when viewed from above, is fitted into the opening 3 of the main rocker arm 1. The sub-rocker arm 7 has one end swingably supported by the sub-rocker shaft 8 located above the rocker shaft 2. The sub rocker shaft 8 is attached to the upper end of the base end portion of the main rocker arm 1 and is arranged in parallel with the rocker shaft 2. The sub rocker arm 7 has a cam follower portion 9 on its upper surface, and is constantly lifted upward from below by a coil spring 10 and a plunger 11 (see FIG. 2).

A cam shaft (not shown) is arranged in parallel with the rocker shaft 2 above the roller cam follower 4 and the cam follower portion 9, and the cam shaft has a first cam 13 and a second cam 13 having different profiles. The cam 14 is formed side by side. The first cam 13 comes into contact with the roller cam follower 4 of the main rocker arm 1, and is formed in a profile having a small valve lift amount. The second cam 14 is in sliding contact with the cam follower portion 9 of the sub rocker arm 7, and has a profile with a relatively large valve lift amount.

As a connecting mechanism for connecting the main and auxiliary rocker arms 1 and 7, as shown in FIG. 5, a circular through hole 15 is formed inside the auxiliary rocker arm 7 in parallel with the rocker shaft 2. A bottomed cylindrical plunger 16 is slidably accommodated therein. The plunger 16 has a length substantially equal to the width of the sub-rocker arm 7, and has a spring accommodating portion 17 whose one end is open, and a pair of elongated holes 18 at an axial intermediate portion. Are formed so as to face each other. A shaft-shaped spring stopper 19 is arranged so as to cross the elongated hole 18, and a return spring 20 is arranged in a compressed state between the spring stopper 19 and the bottom portion 16a of the plunger 16. Both ends of the spring stopper 19 are supported by being inserted into holes provided in the sub-rocker arm 7, and a flat surface is formed in the central portion so as to stably receive the return spring 20. The plunger 16 is urged toward the roller cam follower 4 side of the main rocker arm 1 by the spring force of the return spring 20.

On the other hand, a circular engagement hole 21 is formed so as to penetrate the through hole 15 of the sub rocker arm 7 on the side of the opening 3 of the main rocker arm 1 where the tip of the plunger 16 faces. The engagement hole 21 has the same diameter as the through hole 15, and the tip of the plunger 16 can be fitted therein.

On the side surface of the opening 3 of the main rocker arm 1 facing the bottom 16a side of the plunger 16, a circular pin fitting hole 22 is formed so as to be continuous with the through hole 15 of the sub rocker arm 7. A cylindrical push pin 23 is slidably fitted therein. A hydraulic pressure supply passage 24 is formed inside the main rocker arm 1 so as to supply hydraulic pressure to the back side of the push-out pin 23, and this communicates with an oil pressure supply passage 26 in the rocker shaft 2 via an oil hole 25. (See FIG. 3).

Therefore, when the predetermined hydraulic pressure is not introduced into the hydraulic pressure supply passage 26, the plunger 16 is retracted by the spring force of the return spring 20, and the push pin 23 is also retracted by being pushed by this. Therefore, as shown in FIG. 5, the sub rocker arm 7 and the main rocker arm 1 are separated from each other. Therefore, the main rocker arm 1 swings following the first cam 13. On the other hand, when a predetermined hydraulic pressure is introduced into the hydraulic pressure supply passage 26, the push-out pin 23 projects and the tip end thereof fits into the through hole 15. At the same time, the push pin 23 presses the plunger 16 so that the tip of the plunger 16 fits into the engagement hole 21 of the main rocker arm 1. Therefore, the sub-rocker arm 7 and the main rocker arm 1 are connected to each other, and the main rocker arm 1 swings together with the sub-rocker arm 7 that follows the second cam 14.

Next, the valve clearance adjusting mechanism of the rocker arm will be described. Small hydraulic lash adjusters 31 are attached to the left and right sides of the tip end of the main rocker arm 1, that is, the swing end, respectively. 31 presses a pair of valves of the same cylinder, for example, a valve stem end 32a of an intake valve 32. Further, a reservoir chamber 33 is formed in parallel with the lash adjuster 31 substantially at the center of the swinging end of the main rocker arm 1, that is, at an intermediate position between the pair of lash adjusters 31. As shown in FIG. 3, the reservoir chamber 33 is formed on the upper surface of the main rocker arm 1 by attaching a separate cap 34 to the upper surface of the circular recess formed on the main rocker arm 1 side. A fine air vent hole 35 is formed in the upper surface 34a of the.

As shown in FIG. 3, the reservoir chamber 33 and the lubricating oil passage 36 in the rocker shaft 2 are connected to the oil passage 37 for the lash adjuster formed along the upper surface of the main rocker arm 1 and the rocker shaft 2. It is always in communication through the oil hole 38. The lash adjuster oil passage 37 is connected to a relatively upper portion of the reservoir chamber 33. Further, the reservoir chamber 33 and the lash adjusters 31 on both sides are communicated with each other through an oil passage 39 which opens relatively downward of the reservoir chamber 33. The end of the lash adjuster oil passage 37 is closed by a spherical plug 30.

On the other hand, the sub-rocker shaft 8 located above the rocker shaft 2 is also hollow, and the lubricating oil passage 40 is formed inside. As shown in FIG. 3, the lash adjuster oil passage 37 passing below the sub-rocker shaft 8 and the lubricating oil passage 40 communicate with each other by a communication passage 41 extending substantially in the vertical direction. As shown in FIGS. 1 and 2, the base end bearing portion 7a of the sub rocker arm 7 is provided with a pair of relatively thin splash holes 42 toward the sliding contact portion between the second cam 14 and the sub rocker arm 7. It is formed through. Corresponding to the splash hole 42, a communication port 43 is formed in the sub rocker shaft 8 so that the splash hole 42 and the lubricating oil passage 40 therein are always communicated with each other.

In the structure of the above embodiment, the lubricating oil is constantly supplied from the lubricating oil passage 36 in the rocker shaft 2 to the reservoir chamber 33 through the oil passage 37 for the lash adjuster, and further from this reservoir chamber 33 through the oil passage 39. It is supplied to each lash adjuster 31. As a result, each lash adjuster 31 acts to keep the valve clearance at zero.

A part of the lubricating oil passing through the lash adjuster oil passage 37 flows into the lubricating oil passage 40 in the upper sub-rocker shaft 8 through the communication passage 41, and from there, passes through the communication port 43 and the splash hole 42. , Toward the sliding contact portion between the second cam 14 and the sub rocker arm 7. Since the splash hole 42 is very close to the sliding contact portion of both, and the lubricating oil is sprayed from the side along the sliding contact surface of the both, reliable lubrication of the sliding contact portion can be performed. .. Moreover, since the rocking angle of the sub-rocker arm 7 is relatively small, the lubricating oil will always be ejected without making the communication port 43 of the sub-rocker shaft 8 so large, that is, regardless of the rocking position. It can be lubricated well. Further, since the communication port 43 can be made small, the rigidity of the sub rocker shaft 8 is less deteriorated.

On the other hand, since the sub rocker shaft 8 is located above the lash adjuster oil passage 37, the air mixed in the lubricating oil is fed from the lash adjuster oil passage 37 to the inside of the sub rocker shaft 8. A large amount is collected in the oil passage 40, and is discharged to the outside together with the lubricating oil ejected from the splash hole 42. That is, the amount of air flowing toward the reservoir chamber 33 side is reduced by that much, the reservoir chamber 33 can be downsized, and the reliable operation of the hydraulic lash adjuster 31 is ensured.

In the above embodiment, only one sub-rocker arm 7 is provided on the main rocker arm 1 so that the two-step lift characteristics can be switched. The present invention can be similarly applied to a device provided with a plurality of sub-rocker arms so as to obtain

[0026]

[Effect of the device]

 As is apparent from the above description, according to the valve drive device for an internal combustion engine according to the present invention, in the one in which the valve lift characteristic is switched by connecting and disconnecting the main rocker arm and the sub rocker arm, the sub rocker arm and the cam It is possible to effectively and surely lubricate the sliding contact portion with. In addition, most of the air that was mixed in the lubricating oil that goes to the lash adjuster is discharged to the outside together with the lubricating oil that is ejected from the splash holes, and entry into the lash adjuster is suppressed. Therefore, the reliable operation of the lash adjuster can be ensured without increasing the size of the reservoir chamber.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a valve drive device according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a cross-sectional view taken along the line CC of FIG.

FIG. 5 is a partially cutaway cross-sectional view showing the structure of a coupling mechanism.

[Explanation of symbols]

 1 ... Main rocker arm 2 ... Rocker shaft 7 ... Sub rocker arm 8 ... Sub rocker shaft 16 ... Plunger 23 ... Extrusion pin 31 ... Hydraulic lash adjuster 33 ... Reservoir chamber 37 ... Oil passage for lash adjuster 40 ... Lubrication oil passage 41 ... Communication passage 42 ... Splash hole 43 ... Communication port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Nakamura 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Shinichi Hatabe 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Shoji Morita Atsugi Unisia Co., Ltd. 1370 Onna, Atsugi City, Kanagawa Prefecture

Claims (1)

[Scope of utility model registration request] 1. A main rocker arm, one end of which is swingably supported by a rocker shaft, and which swings by being driven by a cam of an upper camshaft, and a main rocker arm mounted on an upper portion of a base end portion of the main rocker arm. The sub-rocker shaft, one end of which is swingably supported by the sub-rocker shaft, and the sub-rocker arm that is swung by being driven by another cam of the cam shaft, and the swing end of the main rocker arm. A hydraulic lash adjuster, a valve that is driven to open and close by a main rocker arm via the hydraulic lash adjuster, a connecting mechanism that hydraulically connects the sub rocker arm and the main rocker arm, and a lubricating oil passage in the rocker shaft to The oil passage for the lash adjuster leading to the hydraulic lash adjuster, and the auxiliary tank above the oil passage for the lash adjuster. The communication passage that guides the lubricating oil to the lubricating oil passage in the camshaft, the splash hole penetratingly formed in the bearing portion of the sub rocker arm toward the sliding contact portion between the sub rocker arm and the cam, and the splash hole and the sub rocker shaft A valve drive device for an internal combustion engine, comprising: a communication opening formed in an auxiliary rocker shaft so as to always communicate with a lubricating oil passage.