JPH0533620A - Valve driving device for internal combustion engine - Google Patents

Abstract

PURPOSE:To shorten the dimension in the axial direction of a connecting mechanism for the whole smaller and lighter device, which switches valve characteristics by making a sub rocker arm connected or disconnected for a main rocker arm. CONSTITUTION:A pin engagement hole 11 is recessed-provided at a sub rocker arm 4, into which an engagement pin 12 is fitted go that it may slide. The engagement pin 12 houses a return spring 16 in it to be forced in the retract direction. At the bottom surface of the pin engagement hole 11, an oil supply passage 20 is communicated, and the engagement pin 12 is protruded by oil pressure. At a main rocker arm, there is formed an engagement hole 17 into which the engagement pin 12 can be fitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a valve drive device for an internal combustion engine, in which valve lift characteristics can be switched by selectively using cams having different profiles.

[0002]

2. Description of the Related Art Generally, a valve drive system for an internal combustion engine transmits a cam lift to an intake valve and an exhaust valve via a rocker arm and a swing arm, and controls an intake valve and an exhaust valve urged in a closing direction by a valve spring. Although it has a push-open structure, the valve lift characteristics are different 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. Various devices have been proposed.

As an example thereof, Japanese Patent Laid-Open No. 63-10 is used.
In Japanese Patent No. 6309, etc., two types of cams having different profiles are arranged side by side, and a main rocker arm and a sub rocker arm which follow each other are switched to a connected state or a detached state as required, which is known. ing.

FIG. 17 and FIG. 18 show a conventional valve drive device described in the above publication, in which a pair of main rocker arms 62 are swingably supported by a rocker shaft 61 and the pair of main rocker arms 62 are rocked. A sub rocker arm 63 is also swingably supported between the rocker arms 62.
The rocking ends of the pair of main rocker arms 62 are linked to valves of the same cylinder, for example, intake valves 64. The sub rocker arm 63 is urged upward by a spring (not shown). And each rocker arm 62, 6
A pair of first cams 66 having a small valve lift amount for pressing the main rocker arm 62 and a second cam 67 having a large valve lift amount for pressing the sub rocker arm 63 are arranged on the cam shaft 65 arranged above the third shaft 3. Is formed by.

A through hole 68 is formed in the sub rocker arm 63 in parallel with the rocker shaft 61, and a cylindrical intermediate pin 69 is slidably fitted therein. A plunger fitting hole 70 is formed in one of the main rocker arms 62 so as to be continuous with the through hole 68, and a plunger 71 is slidably fitted therein. A hydraulic chamber 72 is formed on the back surface of the plunger 71 and communicates with a hydraulic supply passage 73 in the rocker shaft 61. Then, in the other main rocker arm 62, the through hole 68 is also formed.
A pin fitting hole 74 is provided so as to be continuous with the push pin 75. The push pin 75 is slidably fitted therein, and a return spring 76 is arranged in a compressed state on the back side thereof.

FIG. 18 shows a state in which a predetermined hydraulic pressure is applied in the hydraulic chamber 72, and in this state, the rocker arms 62 and 63 are in a disengaged state. Therefore, the swing of the sub rocker arm 63 is not transmitted to the intake valve 64, and the first cam 6
The intake valve 64 is opened / closed by the main rocker arm 62 driven by 6. On the other hand, when the hydraulic pressure in the hydraulic chamber 72 is released, the push pin 75 and the intermediate pin 69 are moved in the axial direction by the spring force of the return spring 76 to connect the main and sub rocker arms 62 and 63. Therefore, the second cam 6
The intake valve 64 is opened and closed by the swing of the sub-rocker arm 63 driven by 7.

Further, in Japanese Patent Laid-Open No. 63-106310, as shown in FIG. 19, a stepped through hole 77 is formed in the main rocker arm 62, the stepped through hole 77 having a diameter slightly smaller on the sub rocker arm 63 side. In the figure, a stepped engagement pin 78 is slidably disposed, and a return spring 79 is disposed on the outer periphery of a small diameter portion of the engagement pin 78. That is, in this example, the engagement pin 78 is always biased in the backward direction. The sub-rocker arm 63 is provided with an engaging hole 80 into which the tip of the engaging pin 78 can be fitted. On the back side of the engaging pin 78,
A hydraulic chamber 82 is defined by a plug 81 that closes the through hole 77, and the hydraulic chamber 82 communicates with the hydraulic pressure supply passage 73. Therefore, in this case, when the hydraulic pressure is supplied, the engagement pin 78 projects as shown in the figure, and the main and sub rocker arms 62 and 63 are brought into a connected state.

[0008]

In the former configuration, the connecting mechanism for connecting the main and sub rocker arms 62 and 63 is as follows.
Since the plunger 71 operated by hydraulic pressure, the intermediate pin 69 having a length equal to the width of the sub rocker arm 63, and the push pin 75 pressed by the return spring 76 are arranged in series, The overall axial length is considerably larger. Therefore, the main rocker arm 62
It is difficult to reduce the axial width of the device, and the overall size increases, and the main and auxiliary rocker arms 6 reciprocate.
There is a problem that the inertial mass of 2,63 becomes large.

Further, in the latter configuration, the engaging pin 78
The main and sub rocker arms 62 and 63 are connected by only the above, but the engagement pin 78 has a stepped shape, and only the large diameter portion thereof is fitted in the through hole 77. Therefore, when the engagement pin 78 receives a force in the radial direction during the connection, the rattling is likely to occur, the main and auxiliary rocker arms 62 and 63 cannot be accurately connected, and the valve lift characteristic is likely to be distorted. .. Further, the rattling accelerates the wear of each part, resulting in low durability. In order to ensure the fitting state with the through hole 77, the large diameter portion of the engagement pin 78 must be lengthened, and eventually the axial dimension of the coupling mechanism cannot be reduced. ..

Further, since the hydraulic chamber 82 must be defined by the plug 81 due to the insertion of the stepped engagement pin 78, various problems such as durability of the seal may occur.

[0011]

According to the present invention, there is provided a main rocker arm which is swingably supported by a rocker shaft and swings by being driven by one of two kinds of cams having different profiles, and a main rocker arm adjacent to the main rocker arm. And a rocker arm that is rockably moved by the other of the cams, a valve that is opened and closed by the main rocker arm, and a connecting mechanism that hydraulically connects the main rocker arm and the sub rocker arm. In the valve drive device for an internal combustion engine, comprising: a pin fitting hole provided in one of the main rocker arm or the sub rocker arm,
An engaging hole formed in the other of the main rocker arm or the sub-rocker arm so as to be continuous with the pin fitting hole, and slidably fitted in the pin fitting hole, and the engaging hole when protruding. A bottomed cylindrical engagement pin that can be fitted into the engagement pin, a return spring that is disposed in a spring accommodating portion inside the engagement pin, and that urges the engagement pin in the backward direction, and the back surface of the engagement pin. And a hydraulic pressure supply passage for guiding hydraulic pressure to the side.

[0012]

When the hydraulic pressure is supplied to the back side of the engaging pin, the engaging pin projects and the tip end thereof fits into the engaging hole. As a result, the main and sub rocker arms are integrally connected. At this time, the engagement pin maintains a state in which the outer peripheral surface thereof is widely fitted to the inner peripheral surface of the pin fitting hole. Further, when the hydraulic pressure is released, the engagement pin retracts due to the spring force of the return spring and disengages from the engagement hole. As a result, the sub rocker arm is separated from the main rocker arm.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

1 to 4 show an embodiment of a valve drive device according to the present invention, in which a pair of main rocker arms 2 are swingably supported at one end by a rocker shaft 1, and An auxiliary rocker arm 4 is supported between the main rocker arms 2 of the same so as to be swingable at one end.
That is, the sub rocker arm 4 is arranged such that both parallel side surfaces thereof are sandwiched by the main rocker arm 2. The pair of main rocker arms 2 has a cam follower portion 5 on the upper surface of the central portion and an adjusting screw 6 at the swinging end, and the adjusting screw 6 has a pair of valves of the same cylinder, for example, a valve stem end of an intake valve 7. 7a is pressed (see FIG. 2). Further, the sub rocker arm 4 is formed to be relatively short, and a cam follower portion 8 is provided on the upper surface of the tip end portion thereof (see FIGS. 3 and 4).

A camshaft (not shown) disposed above the rocker shaft 1 has a pair of first cams 9 having a small valve lift amount which come into sliding contact with the cam follower portion 5 of the main rocker arm 2 and a cam follower portion of the sub rocker arm 4. A second cam 10 having a large valve lift amount that is in sliding contact with the second cam 8 is formed. The sub rocker arm 4 is urged to rotate upward by a spring (not shown).
The sliding contact state with the second cam 10 is maintained even when the second cam 10 is disengaged.

Next, a pair of connecting mechanisms for connecting the main and auxiliary rocker arms 2 and 4 will be described. This pair of connecting mechanisms
It is configured symmetrically with respect to the left and right main rocker arms 2, and circular pin fitting holes 11 are recessed in parallel with the rocker shaft 1 on both left and right side surfaces of the sub rocker arm 4.
A bottomed cylindrical engagement pin 12 is slidably fitted in each. The engagement pin 12 has a length substantially equal to the depth of the pin fitting hole 11, and the pin fitting hole 1 is provided over the entire length.
The outer circumference is formed into a simple cylindrical surface so as to fit with 1. Further, as shown in FIG. 5, a spring accommodating portion 13 having a bottom portion 12a on the bottom surface side of the pin fitting hole 11 and having an opening on the main rocker arm 2 side is provided at the center and is recessed in the center. A pair of elongated holes 14 are formed in the intermediate portion so as to face each other. A shaft-shaped spring stopper 15 is arranged so as to cross the elongated hole 14, and the spring stopper 15 and the engaging pin 12 bottom part 1 are provided.
The return spring 16 is arranged in a compressed state with the 2a. Both ends of the spring stopper 15 are supported by being inserted into holes provided in the sub-rocker arm 4, and a flat surface 15a is formed in the center so as to stably receive the return spring 16.

6 to 8 show modified examples of the spring stopper 15 portion, and in the example of FIG.
The tip end portion 15b is an inclined surface so that the spring stopper 15 can be easily inserted into the compressed return spring 16. In the example of FIG. 7, the spring stopper 15
Is configured to be supported by the sub-rocker arm 4 in a so-called cantilever state. In this case, since it is necessary to position the spring stopper 15 in the direction, a positioning projection 15c that engages with a notch (not shown) on the sub rocker arm 4 side is provided. Further, in the example of FIG. 8, one end of the long hole 14 is opened.

On the other hand, a circular engagement hole 17 is formed on the side surface of the main rocker arm 2 where the tips of the engagement pins 12 face each other so as to be continuous with the pin fitting hole 11 of the sub rocker arm 4.
Are formed through. The engagement hole 17 has the same diameter as the pin fitting hole 11, and the tip of the engagement pin 12 can be fitted therein.

Further, one end of a hydraulic pressure supply passage 20 is opened at the bottom surface of the engagement hole 17 so as to supply hydraulic pressure to the rear surface side of the engagement pin 12. This hydraulic supply passage 20
Passes through the inside of the sub-rocker arm 4, and this is the oil hole 2
1 to the hydraulic pressure supply passage 22 in the rocker shaft 1.

In the above structure, when the predetermined hydraulic pressure is not introduced into the hydraulic pressure supply passage 22, the engaging pin 12 is retracted by the spring force of the return spring 16 and the engaging hole 1
It will be in a state of escape from 7. Therefore, as shown in FIG. 1, the auxiliary rocker arm 4 and the main rocker arm 2 are separated from each other, and the intake valve 7 is opened and closed by the first cam 9. On the other hand, when a predetermined hydraulic pressure is introduced into the hydraulic pressure supply passage 22, the engagement pin 12 projects as shown in FIG. 9, and the tip end thereof fits into the engagement hole 17. Therefore, the sub rocker arm 4 and the main rocker arm 2 are connected to each other, and the intake valve 7 is opened and closed according to the swing of the sub rocker arm 4 that is driven by the second cam 10.

As described above, in the structure of the above-described embodiment, only the engaging hole 17 needs to be provided on the main rocker arm 2 side, and the size and weight of the connecting mechanism can be reduced. The outer peripheral surface of the engaging pin 12 is a simple cylindrical surface, and in the connected state, the pin fitting hole 11 and the engaging hole 17 are formed.
Since the whole is relatively tightly fitted over both of them, there is no rattling even if a radial force is applied, and the main and sub rocker arms 2 and 4 can be accurately connected. it can.

Further, in the above construction, since the hydraulic chamber 18 (see FIG. 9) is defined at the bottom of the pin fitting hole 11 provided in the sub rocker arm 4, no special seal or the like is required. It also has excellent durability.

Next, FIGS. 10 to 15 show different embodiments of the present invention.

In this embodiment, the main rocker arm 32, which is rockably supported by the rocker shaft 31, has a wide width which is substantially rectangular as viewed from above. That is, the main rocker arm 32 is integrated in a frame shape in which a substantially rectangular opening 33 is formed so as to be offset to one side, and the first rocker arm 32 is provided at a position offset to the side opposite to the opening 33.
A roller cam follower 34 that contacts the cam 45 is provided. A pair of hydraulic lash adjusters 35 are attached to the swinging end of the main rocker arm 32, and the lash adjusters 35 press the valve stem end 7a of the intake valve 7, for example. Further, a reservoir chamber 37 having an air vent hole 36 at the top is formed in the middle of the pair of lash adjusters 35, and the reservoir chamber 37 and each lash adjuster 35 communicate with each other through an oil passage 38 (Fig. 13, see FIG. 14). Engine oil is constantly supplied to the reservoir chamber 37 from a lubricating oil passage 41 in the rocker shaft 31 via oil passages 39 and 40 in the main rocker arm 32. Incidentally, the upper surface of the reservoir chamber 37 is formed in a tapered shape so as to be at the uppermost position while avoiding the cam locus L shown by the chain double-dashed line as shown in FIG. In addition, the oil passage 3 is located at a position once downward from the reservoir chamber 37.
Since 8 is connected, the air is reliably discharged from the reservoir chamber 37, and the air is less likely to enter the lash adjuster 35 side.

On the other hand, the opening 3 of the main rocker arm 31
A sub-rocker arm 42, which is substantially rectangular when viewed from above, is fitted in 3. The sub rocker arm 42 is swingably supported by the sub rocker shaft 43 located above the rocker shaft 31. The sub rocker shaft 43 is provided on the main rocker arm 32, is arranged in parallel with the rocker shaft 31, and has a hydraulic pressure supply passage 49 described later formed therein. In addition, the sub rocker arm 4 above
2 is a cam follower portion 44 that is in contact with the second cam 46 on the upper surface.
And is lifted to the cam 46 side from below by a coil spring 47 and a plunger 48.

The pair of connecting mechanisms for connecting the main and sub rocker arms 32 and 42 have the same construction as that of the above-mentioned embodiment, and the engaging pin 52 can slide in the pin fitting hole 51 of the sub rocker arm 42. The return spring 53 biases the engagement pin 52 in the backward direction. One end of the return spring 53 has a shaft-shaped spring stopper 5 as in the above-described embodiment.
It is locked by 4. Then, the pin fitting hole 5
A hydraulic pressure supply passage 55 that supplies hydraulic pressure to the rear surface side of the engagement pin 52 communicates with the bottom surface of the No. 1. This hydraulic pressure supply passage 5
5 is connected to a hydraulic pressure supply passage 49 in the sub rocker shaft 43, and as shown in FIG.
Finally, it communicates with the hydraulic pressure supply passage 58 in the rocker shaft 31 via.

Engagement holes 59 and 60 are formed on both side surfaces of the opening 33 where the tips of the engagement pins 52 face each other so as to be continuous with the pin fitting holes 51. Here, one engagement hole 59 is formed in the frame portion 32 of the main rocker arm 32.
The engaging hole 60 is formed so as to penetrate through a and the tip of the other engaging hole 60 is sealed. The latter engagement hole 6
For 0, an oil discharge hole 60a is formed below to discharge the leaked oil (see FIG. 13).

Also in this embodiment, the hydraulic pressure supply passage 5
When hydraulic pressure is introduced to the rear surface of the engagement pin 52 via 8, 49, 55, the engagement pin 52 moves in the axial direction, and the sub rocker arm 42 and the main rocker arm 32 move to the sub rocker arm 4.
The left and right sides of 2 are firmly connected. When the hydraulic pressure is released, the state shown in FIG. 10 is restored, and both rocker arms 32, 42 are in the disengaged state.

In the embodiment in which the main rocker arm 32 is formed in the frame shape as described above, the frame portion 32a outside the opening 33 of the main rocker arm 32 is used only for supporting the sub rocker arm 42. As described above, since only the engaging hole 59 is required as the connecting mechanism, the frame portion 32a can be made extremely thin, and the overall size can be reduced. Further, since the sub rocker arm 42 is supported by the main rocker arm 32 from both sides, it is possible to secure a sufficiently large strength at the time of connection.

Next, in the embodiment shown in FIG. 16, the sub-rocker arm 42 has a small size, and the connecting mechanism is provided on only one side. Since the basic structure of this embodiment is the same as that of the above-described embodiment shown in FIGS. 10 to 15, the same parts are designated by the same reference numerals, and a duplicate description will be omitted. That is, in this embodiment, the opening 33 of the main rocker arm 32 is provided.
An engagement hole 59 is formed through the outer frame portion 32a, and an engagement pin 52 is disposed on the sub rocker arm 42 so as to face the engagement hole 59. In the figure, the engagement pin 52 is projected to connect the main and auxiliary rocker arms 32 and 42.

According to this embodiment, since the interference between the oil passages 39, 40 for the roller cam follower 34 and the lash adjuster 35 and the coupling mechanism is avoided, the overall size can be further reduced.

[0032]

As is apparent from the above description, according to the valve drive device for an internal combustion engine of the present invention, the coupling mechanism is mainly composed of the engagement pin arranged on one of the main and sub rocker arms. On the other hand, since it is sufficient to form only the engagement hole, the dimension of the connecting mechanism in the axial direction can be shortened, and the entire rocker arm can be reduced in size and weight. Further, since the return spring is housed inside the engaging pin and the outer peripheral cylindrical surface of the engaging pin is fitted so as to straddle the pin fitting hole and the engaging hole, the engaging pin is radiated in the radial direction during connection. There is no rattling even when subjected to force, the main and sub rocker arms are accurately connected, and the durability is excellent. Moreover, unlike the prior art, it is not necessary to use a plug or the like to define the hydraulic chamber, and a problem such as sealing does not occur.

[Brief description of drawings]

FIG. 1 is a sectional 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 an enlarged cross-sectional view showing a main part of an engaging pin portion.

FIG. 6 is a cross-sectional view showing a different embodiment of the engaging pin portion.

FIG. 7 is a sectional view showing a different embodiment of the engaging pin portion.

FIG. 8 is a sectional view showing still another embodiment of the engaging pin portion.

FIG. 9 is a cross-sectional view of essential parts showing a connected state of the main and sub rocker arms.

FIG. 10 is a sectional view showing another embodiment of the valve drive device according to the present invention.

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

12 is a cross-sectional view taken along the line EE of FIG.

13 is a cross-sectional view taken along the line FF of FIG.

14 is a cross-sectional view taken along the line GG of FIG.

15 is a sectional view taken along line HH of FIG.

FIG. 16 is a sectional view showing still another embodiment of the valve driving device according to the present invention.

FIG. 17 is a plan view of an essential part showing an example of a conventional valve drive device.

FIG. 18 is a cross-sectional view showing a coupling mechanism for the main and sub rocker arms of this conventional example.

FIG. 19 is a cross-sectional view showing a conventional example having a different connecting mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rocker shaft 2 ... Main rocker arm 4 ... Sub rocker arm 11 ... Pin fitting hole 12 ... Engagement pin 13 ... Spring accommodation part 16 ... Return spring 17 ... Engagement hole 20 ... Hydraulic supply passage

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichi Hatabe 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (1)

Claims: 1. A rocker shaft is swingably supported,
And a main rocker arm that swings following one of two cams having different profiles, and a sub-rocker arm that is swingably arranged adjacent to the main rocker arm and that swings following the other of the cams. In the valve drive device for an internal combustion engine, which comprises a valve that is opened and closed by the main rocker arm and a connecting mechanism that hydraulically connects the main rocker arm and the sub rocker arm, the connecting mechanism includes a main rocker arm or a sub rocker arm. A pin fitting hole recessed in one side, and an engagement hole formed in the other of the main rocker arm or the sub rocker arm so as to be continuous with the pin fitting hole, and slidable in the pin fitting hole. A bottomed cylindrical engagement pin that is fitted and that can be fitted into the engagement hole when protruding, and is arranged in a spring accommodating portion inside the engagement pin, One engaging a return spring for engagement pin is biased in the backward direction, an internal combustion engine valve drive device including a hydraulic pressure supply passage for introducing the hydraulic pressure to the back side of the engaging pin.