JP2005233137A - Variable valve system mechanism for internal combustion engine and method for adjusting same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity and easiness of maintenance in a variable valve system mechanism driving a plurality of valve elements collectively. <P>SOLUTION: This mechanism is provided with a variable rocking range mechanism 38 rocking with synchronizing with rotation of a cam 38 and changing a range of rock according to rotation position of a control shaft 28. Both ends of a connection adjusting pin 30 penetrating through the variable rocking range mechanism 38 are inserted in retention holes of rocking cam arm 26a, 26b. The rocking cam arms 26a, 26b rock together with the variable rocking range mechanism 38 give the valve elements 12a, 12b lift while receiving valve spring force. The connection adjusting pins 30 are classified in ranks by diameter of a part retained in the retention hole of the rocking cam arm 26a. Valve open characteristics of two valve elements 12a 12b can be adjusted by changing the rank. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable valve mechanism for an internal combustion engine and a method for adjusting the same, and more particularly, a variable valve mechanism suitable as a mechanism for operating a plurality of valve bodies collectively, and a method for adjusting such a mechanism. The present invention relates to a method for adjusting a variable valve mechanism.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-371816, a configuration in which a single variable valve mechanism is arranged for each cylinder of an internal combustion engine is known. In this system, each variable valve mechanism is configured to drive two valve bodies arranged in each cylinder.

  Specifically, each variable valve mechanism includes a rocker arm integrally formed so that two valve bodies can be driven simultaneously. A swing mechanism is provided between the rocker arm and the cam to transmit the pressing force of the cam to the rocker arm by swinging in synchronization with the rotation of the cam.

  The swing mechanism includes a control shaft, and is configured to change the swing range in synchronization with the rotation of the cam by adjusting the rotational position of the control shaft. Further, the swing mechanism and the rocker arm are configured so that the swing amount of the rocker arm changes when the swing range of the swing mechanism changes. If the rocking amount of the rocker arm changes, the valve opening period (hereinafter referred to as “working angle”) and the lift amount of the valve body change. For this reason, according to the conventional system described above, the lift amount and the operating angle of the two valve bodies arranged in the individual cylinders can be collectively changed by adjusting the position of the control shaft.

JP 2002-371816 A JP 2002-266610 A

  When two valve bodies are arranged in a single cylinder, it is necessary to build a variable valve mechanism so that both valve bodies exhibit desired valve opening characteristics. In the conventional system described above, the two valve bodies simultaneously open and close when the integrally formed rocker arm swings. Therefore, in order to achieve the desired valve opening characteristics of the left and right valve bodies, respectively. It is necessary to process the molded rocker arm with sufficiently high accuracy and to assemble the swing mechanism and the rocker arm with sufficiently high accuracy.

  Further, the two valve bodies arranged in the individual cylinders may show different temporal changes for each valve body. If the valve opening characteristics of one valve body and the valve opening characteristics of the other valve body can be adjusted independently, even if such a situation occurs, it is relatively easy to open both valve bodies. The characteristics can be aligned. However, in the conventional system described above, since the rocker arm that is commonly used for the two valve bodies is integrally formed, the valve opening characteristics of the two valve bodies cannot be adjusted independently. Therefore, in this system, when different time-dependent changes occur in the valve opening characteristics of the two valve bodies, the entire rocker arm must be replaced during maintenance.

  As described above, the conventional system described above is not necessarily excellent in productivity under the requirement of appropriately adjusting the valve opening characteristics of the two valve bodies arranged in each cylinder. Also, it was not excellent in maintainability.

The present invention has been made to solve the above-described problems, and can operate a plurality of valve bodies with desired valve opening characteristics, and realizes excellent productivity and excellent maintainability. It is a first object of the present invention to provide a variable valve mechanism for an internal combustion engine that can be used.
Furthermore, the present invention provides a method for adjusting a variable valve mechanism of an internal combustion engine that can operate a plurality of valve bodies with desired valve opening characteristics and realizes excellent productivity and excellent maintainability. Is the second purpose.

In order to achieve the above object, a first invention is a variable valve mechanism for an internal combustion engine,
A swing range variable mechanism that swings in synchronization with the rotation of the cam of the internal combustion engine and changes the swing range according to the position of the control shaft;
A connection adjusting pin held by the swing range variable mechanism;
A plurality of swing cam arms each having a holding hole for holding the connection adjusting pin, and being connected to the swing range variable mechanism by inserting the connection adjusting pin into the holding hole;
A valve body provided corresponding to each of the swing cam arms and opened by being biased by each swing cam arm;
A valve spring that biases the swing cam arm in a direction to close the valve body;
At least one of the plurality of swing cam arms is characterized in that a diameter of the connection adjusting pin in a portion held by the holding hole is smaller than a diameter of the holding hole.

The second invention is the first invention, wherein
The holding holes provided in the plurality of swing cam arms have the same diameter,
The connection adjusting pins have different diameters in the portions held in the respective holding holes.

The third invention is the second invention, wherein
The holding hole for holding one end of the connection adjustment pin is a non-through hole,
The holding hole for holding the other end of the connection adjusting pin is a through hole,
The connection adjusting pin is characterized in that a portion inserted into the through hole is provided with a smaller diameter than a portion adjacent to the portion.

  The fourth invention is characterized in that, in the first invention, the holding holes provided in the plurality of swing cam arms have different diameters.

The fifth invention is a method for adjusting a variable valve mechanism of an internal combustion engine,
A swing range variable mechanism that swings in synchronization with the rotation of the cam of the internal combustion engine and changes the swing range according to the position of the control shaft;
A connection adjusting pin held by the swing range variable mechanism;
A plurality of swing cam arms each having a holding hole for holding the connection adjusting pin, and being connected to the swing range variable mechanism by inserting the connection adjusting pin into the holding hole;
A valve body provided corresponding to each of the swing cam arms and opened by being biased by each swing cam arm;
An adjustment method for a variable valve mechanism of an internal combustion engine comprising a valve spring that biases the swing cam arm in a direction to close the valve body,
Preparing a plurality of ranks of coupling adjustment pins having different combinations of diameters of the portions respectively held by the holding holes of the plurality of swing cam arms;
Selecting an optimal connection adjusting pin from the plurality of ranks;
Assembling the selected connection adjusting pin to the plurality of swing cam arms and the swing range variable mechanism;
It is characterized by including.

The sixth invention is a method of adjusting a variable valve mechanism of an internal combustion engine,
A swing range variable mechanism that swings in synchronization with the rotation of the cam of the internal combustion engine and changes the swing range according to the position of the control shaft;
A connection adjusting pin held by the swing range variable mechanism;
A plurality of swing cam arms each having a holding hole for holding the connection adjusting pin, and being connected to the swing range variable mechanism by inserting the connection adjusting pin into the holding hole;
A valve body provided corresponding to each of the swing cam arms and opened by being biased by each swing cam arm;
An adjustment method for a variable valve mechanism of an internal combustion engine comprising a valve spring that biases the swing cam arm in a direction to close the valve body,
Preparing a plurality of ranks of swing cam arms having different diameters of the holding holes;
Determining a reference swing cam arm as one of the plurality of swing cam arms;
For each of the remaining plurality of swing cam arms, selecting a swing cam arm that is optimally combined with the reference swing cam arm from the plurality of ranks;
Assembling the reference swing cam arm, the selected swing cam arm, the connection adjusting pin, and the swing range variable mechanism;
It is characterized by including.

  According to the first aspect, since the swing cam arm is connected to the swing range variable mechanism by the connection adjusting pin, it can be easily replaced. At least one of the swing cam arms is formed so that the diameter of the holding hole is larger than the diameter of the connection adjusting pin held therein. When the valve element is opened, the swing cam arm receives a reaction force of the valve spring so that a part of the holding hole comes into contact with the connection adjusting pin. The valve opening characteristic of the valve body (referred to as “regulating valve body”) driven by the swing cam arm is determined by the posture of the swing cam arm when the contact occurs. The posture is determined by the relationship between the diameter of the holding hole and the diameter of the connection adjusting pin in the portion held by the holding hole. It can be adjusted independently of the valve opening characteristics of the valve body. Therefore, according to the present invention, desired valve opening characteristics can be given to the plurality of valve bodies, respectively, while realizing excellent productivity and excellent maintainability.

  According to the second aspect of the present invention, since the holding holes provided in the plurality of swing cam arms have the same diameter, the productivity of the swing cam arms can be increased. And, since the connection adjusting pins have different diameters in the portions held in the respective holding holes, the valve opening characteristics of the valve bodies driven by the respective swing cam arms can be adjusted independently. Has been.

  According to the third invention, the holding hole for holding one end of the connection adjusting pin is a non-through hole. For this reason, the connection adjusting pin does not come off at the end. According to the invention, the holding hole for holding the other end of the connection adjusting pin is a through hole. However, the connection adjusting pin is provided such that the portion inserted into the through hole has a smaller diameter than the portion adjacent to the portion. The swing cam arm is in a state where a part of the holding hole is brought into contact with the small diameter part held therein by the reaction force of the valve spring. The connection adjustment pin has a step between a small diameter portion and a portion adjacent thereto. If the holding hole comes into contact with the small-diameter portion, the movement of the connection adjusting pin in the axial direction is restricted by the above-described step hitting the side surface of the swing cam arm. For this reason, according to the present invention, it is possible to prevent the connection adjusting pin from coming off without using any special mechanism on the through hole side.

  According to the fourth invention, since the plurality of swing cam arms have the holding holes having different diameters, the valve opening characteristics of the valve bodies driven by the respective swing cam arms can be adjusted independently. Has been.

  According to the fifth invention, according to the combination of the diameters of the portions held by the plurality of swing cam arms, a plurality of ranks of connection adjustment pins are prepared, and the optimum connection adjustment pin is selected and assembled. By doing so, the valve opening characteristics of the valve bodies respectively driven by the plurality of swing cam arms can be adjusted independently.

  According to the sixth invention, a plurality of ranks of swing cam arms having different holding hole diameters are prepared, and the combination of the reference swing cam arm and the reference swing cam arm is optimal. The variable valve mechanism can be assembled by selecting the swing cam arm. In this case, the valve opening characteristics of the valve bodies driven by the individual swing cam arms can be adjusted independently according to the diameters of the holding holes of the swing cam arms.

Embodiment 1 FIG.
[Basic structure of Embodiment 1]
FIG. 1 is a perspective view of a variable valve mechanism according to Embodiment 1 of the present invention. A variable valve mechanism 10 shown in FIG. 1 is arranged for each cylinder included in the internal combustion engine. In this embodiment, it is assumed that two intake valves are arranged in each cylinder of the internal combustion engine 10. The variable valve mechanism 10 includes valve bodies 12a and 12b that function as the two intake valves, and has a function of changing the lift amount and the operating angle (valve opening period) of the valve bodies 12a and 12b. Have.

  The valve shafts 14a and 14b of the valve bodies 12a and 12b are connected to rocker arms 16a and 16b (16b not shown) at their upper ends, respectively. FIG. 2 is a view showing the vicinity of the valve body 12a and the rocker arm 16a from the direction of the arrow II shown in FIG. The other 12b valve body has the same structure as that shown in FIG.

  As shown in FIG. 2, the upper end portion of the valve shaft 14a is connected to one end of the rocker arm 16a. A retainer 18a is fixed near the upper end of the valve shaft 14a. One end of a valve spring 20a disposed so as to surround the valve shaft 14a is in contact with the retainer 18a. The other end of the valve spring 20a is held by a cylinder head (not shown). As a result, the rocker arm 16a is biased in a direction to close the valve body 12a by the valve spring force, that is, upward in FIG.

  The other end of the rocker arm 16a is rotatably supported by a hydraulic lash adjuster 22a. The hydraulic lash adjuster 22a is fixed to a cylinder head (not shown). The rocker arm 16a can swing around a support point by the hydraulic lash adjuster 22a. Further, according to the hydraulic lash adjuster 22a, the position of the rocker arm 16a in the height direction can be automatically adjusted by the hydraulic pressure, and as a result, the tappet clearance can be automatically adjusted.

  A roller 24a is disposed at the center of the rocker arm 16a. A swing cam arm 26a is disposed on the upper portion of the roller 24a. A control shaft 28 and a connection adjusting pin 30 are inserted into the swing cam arm 26a. The variable valve mechanism 10 includes a swing cam arm 26b corresponding to the other valve body 12b (see FIG. 1). The control shaft 28 is a member provided in common to the plurality of cylinders so as to penetrate both the swing cam arms 26a and 26b, and is rotatably held by a cylinder head (not shown).

  On the other hand, the connection adjusting pin 30 is a member incorporated in each variable valve mechanism 10 in order to connect one swing cam arm 26a and the other swing cam arm 26b. The variable valve mechanism 10 of the present embodiment is characterized by the structure of the connection adjusting pin 30 and the assembly method. The characteristic structure and assembly method will be described later in detail with reference to other drawings.

  The swing cam arm 26a can swing about the control shaft 28 as a rotation axis. The swing arm 26a is provided with a concentric circular portion 32a and a pressing portion 34a on the surface in contact with the roller 24a. The concentric circle portion 32a is provided so that the contact surface with the roller 24a forms a concentric circle with the control shaft 28. On the other hand, the pressing portion 34a is provided such that the distance from the center of the control shaft 28 becomes farther toward the tip side. Therefore, as long as the concentric circular portion 32a is in contact with the roller 26a, the swing cam arm 26a swings without pressing the roller 24a, that is, without urging the valve body 12a in the valve opening direction. Can do. In a situation where the pressing portion 34a is in contact with the roller 24a, the swing cam arm 26a swings, so that the valve opening lift can be given to the valve body 12a.

  As shown in FIG. 1, a swing range variable mechanism 36 is provided between the two swing cam arms 26a and 26b. The variable valve mechanism 10 includes a cam 38 fixed to the intake camshaft of the internal combustion engine. The swing range variable mechanism 36 is disposed at a position where mechanical contact with the cam 38 is obtained. The variable valve mechanism 10 includes a lost motion spring 40 for applying a desired urging force to the swing range variable mechanism 36. The swinging range variable mechanism 36 can maintain the mechanical contact with the cam 38 by receiving the biasing force.

  FIG. 3 is an exploded perspective view of the above-described swing range variable mechanism 36 and cam 38. The swing range variable mechanism 36 includes a slide arm 42. The slide arm 42 is provided with a through hole 44 for holding the connection adjusting pin 30 and bearings 46a and 46b for holding the control shaft 28 in a rotatable manner. The slide arm 42 includes a pressed portion 48 on the through hole 44 side when viewed from the bearing portions 46a and 46b, and a roller slide portion 50 on the opposite side. The pressed portion 48 is a portion where the slide arm 42 receives the urging force of the lost motion spring 40.

  The swing range variable mechanism 36 further includes a control arm 52 and an intermediate arm 54. The control arm 52 has an annular portion 56 for holding the control shaft 28 in a state where the control arm 52 is incorporated between the two bearing portions 46 a and 46 b provided in the slide arm 42. The control arm 52 is formed with a fixing hole 58 that penetrates the annular portion 56. On the other hand, the control shaft 28 held therein is provided with a through hole 60 to be overlapped with the fixing hole 58. After the control shaft 28 is inserted into the bearing portions 46 a and 46 b and the annular portion 56, the fixing pin 62 is inserted into the fixing hole 58 and the through hole 60. As a result, the control shaft 28 is integrated with the control arm 52.

  The intermediate arm 54 is connected to the control arm 52 by a rotating shaft 64 at the upper end thereof. Therefore, the intermediate arm 54 can swing with respect to the control arm 52. The intermediate arm 54 is provided with a contact roller 66 to be in contact with the cam 38 at a central portion thereof and a slide roller 68 to be in contact with the roller slide portion 50 at a lower end portion thereof. That is, the intermediate arm 54 is properly assembled to the slide arm 42, whereby the contact roller 66 is pressed by the cam 38 from the upper side, and the slide roller 68 is supported by the roller slide portion 50 from the lower side. It will be in a state to be.

  FIG. 4A is a diagram showing the variable valve mechanism 10 assembled properly in plan view. 4B is a diagram illustrating the configuration illustrated in FIG. 4A in a side view. The swing cam arms 26 a and 26 b are assembled so that the side surfaces thereof are in contact with the side surfaces of the slide arm 42. Further, both end portions of the connection adjusting pin 30 penetrating the slide arm 42 are inserted into the swing cam arms 26a and 26b. For this reason, the swing arms 26a, 26b and the slide arm 42 rotate around the control shaft 28 as a substantially integral member.

  The control shaft 28 is rotatably fixed to the cylinder head by a cylinder head bearing (not shown). The cylinder head bearing is provided at a position adjacent to each of the swing cam arms 26a and 26b. That is, the variable valve mechanism 10 is assembled to the cylinder head in such a state that the variable valve mechanism 10 is sandwiched between the cylinder head bearings disposed on both sides of the swing cam arms 26a and 26b. The displacement of the swing cam arms 26a, 26b in the axial direction of the control shaft 28 can be regulated by the cylinder head bearing.

[Basic operation of the first embodiment]
FIG. 5 shows a cross-sectional view obtained by cutting the variable valve mechanism 10 along the VV straight line shown in FIG. Note that FIG. 5 shows a lost motion spring 40 that is not shown in FIG. Hereinafter, the operation of the variable valve mechanism 10 will be described with reference to FIG.

  The lost motion spring 40 applies a downward biasing force in the drawing to the pressed portion 48 of the slide arm 42 with its upper end fixed to a cylinder head or the like. Since the slide arm 42 is rotatably supported by the control shaft 28, the above urging force is a force that pushes the roller slide portion 50 upward in the drawing, that is, a force that presses the intermediate arm 54 against the cam 38. work. As a result, the state in which the cam 38 and the contact roller 66 are in contact with each other and the slide roller 68 and the roller slide portion 50 are in contact with each other is stably maintained.

In FIG. 5, reference sign θ _C indicates “control shaft rotation angle θ _C ” representing the rotational position of the control shaft 28. Here, for convenience, an angle formed by the axial direction of the fixing pin 62 that fixes the control shaft 28 and the control arm 54 and the vertical direction in the figure is defined as a control shaft rotation angle θ _C. In FIG. 5, the symbol θ _A indicates “arm rotation angle θ _A ” that represents the rotation position of the slide arm 42. Here, for convenience, defined as the front end of the roller slide portion 50 and the straight line connecting the center of the control shaft 28, the angle between the vertical direction in the drawing with the arm rotation angle theta _A.

In the variable valve mechanism 10, the arm rotation angle θ _A is determined by the position of the slide roller 68. The position of the slide roller 68 is determined by the position of the rotation shaft 64 of the intermediate arm 54 and the position of the cam contact roller 66. The position of the rotation shaft 64 is determined by the control shaft rotation angle θ _C , that is, the rotation position of the control shaft 28. Thus, in a situation where the rotational position of the control shaft 28 is fixed, the arm rotation angle theta _A will be determined only by the position of the cam contact roller 66.

The cam contact roller 66 moves in the direction of the slide arm 42 by being pushed by the nose of the cam. At that time, the contact roller 68, while sliding the surface of the roller slide portion 50, to rotate the slide arm 42 in the direction to decrease the arm rotation angle theta _A. Therefore, during the rotation of the cam 38, in synchronization with the rotation, the slide arm 42, repeated rocking while changing the arm rotation angle theta _A in a predetermined range.

Incidentally, the arm rotation angle θ _{A not} only shows a periodic change as the cam 38 rotates, but also changes as the rotational position of the control shaft 28 changes. That is, according to the variable valve mechanism 10, the position of the rotation shaft 64 of the intermediate arm 54 is displaced upward as the control shaft 28 rotates in the direction in which the control shaft rotation angle θ _C decreases. And the position of the contact roller 66 rises, so that the rotating shaft 64 is displaced upward in the figure.

The movement of the contact roller 66 is restricted by the cam 38. For this reason, when the contact roller 66 is displaced upward in the figure, the contact roller 66 is displaced in the right direction in the figure, that is, in the direction approaching the control shaft 28. When the contact roller 66 approaches the control shaft 28, the roller slide portion 50 is pressed by the slide roller 68 which slides over it, the slide arm 42, resulting rotation direction arm rotation angle theta _A becomes smaller .

Therefore, according to the variable valve mechanism 10, if the position of the control shaft 28 is adjusted so that the control shaft rotation angle θ _C becomes a large value, the slide arm 42 is swung in a region where the arm rotation angle θ _A is large. Can be moved. Further, in this mechanism 10, if the position of the control shaft 28 is adjusted so that the control shaft rotation angle θ _C becomes a small value, the slide arm 42 can be swung in a region where the arm rotation angle θ _A is small. .

As described above, the slide arm 42 operates in a state of being substantially integrated with the swing cam arms 26a and 26b disposed on both sides thereof. Therefore, when the control shaft rotation angle theta _C is great value in synchronization with the rotation of the cam 38, the swing cam arm 26a, 26b is, so that the swings large area of arm rotation angle theta _A. On the other hand, when the control shaft rotation angle theta _C is a small value, the swing cam arm 26a, 26b is so that the swings in a small region of the arm rotation angle theta _A.

As described above, the swing cam arm 26a has the concentric circle part 32a and the pressing part 34a (see FIG. 2). In the area arm rotation angle theta _A is large, the concentric part 32a contacts the rocker arm 16a, the valve opening lift valve body 12a does not occur. And in the area | region where arm rotation angle (theta) _A is small, since the press part 34a presses the rocker arm 16a, the valve-opening lift according to the arm rotation angle (theta) _A generate | occur | produces in the valve body 12a.

Accordingly, the valve body 12a, when the swing cam arm 26a swings in a large area of the arm rotation angle theta _A in association with the rotation of the cam 38, small, and, so that the opened short. On the other hand, when the swing cam arm 26a swings in a small region of the arm rotation angle theta _A is, with the rotation of the cam 38, largely the valve body 12a, and becomes the possible long-term opening occurs.

A similar tendency also occurs in the valve opening characteristics of the other valve body 12b. Therefore, according to the variable valve mechanism 10, the valve opening characteristics of the valve bodies 12 a and 12 b can be freely changed by changing the rotational position of the control shaft 28. Specifically, by rotating the control shaft 28 in the direction of increasing the control shaft rotation angle θ _C , the lift amount and the operating angle of the valve bodies 12a and 12b can be reduced, while the reverse rotation is performed. By giving, the lift amount and the working angle can be increased.

[Features of Embodiment 1]
In the variable valve mechanism 10 of the present embodiment, the valve opening characteristics of the valve bodies 12a and 12b are determined by how the swing cam arms 26a and 26b press them, respectively. Swing cam arm 26a, the arm rotation angle theta _A of 26b, since it is intended to be changed at the same time, that is, because the independently are those that can not be changed adjustment, two valve bodies 12a, each desired valve opening to 12b In order to provide the characteristics, specifically, in order to make the valve opening characteristics of the valve bodies 12a and 12b uniform, the swing cam arms 26a and 26b are the same when the variable valve mechanism 10 is assembled. Thus, the state of pressing the valve bodies 12a and 12b must be realized.

  Such a request can also be realized by, for example, building components of the variable valve mechanism 10 in advance with high accuracy and assembling them with high accuracy. However, when such a method is employed, high machining accuracy and high assembly accuracy are required, and thus the cost of the variable valve mechanism 10 cannot be avoided. The variable valve mechanism 10 of the present embodiment is characterized in that the above-described requirements can be satisfied without increasing the cost. Hereinafter, a characteristic structure and an assembly method for realizing the effect will be described.

  FIG. 6 is a cross-sectional view obtained by cutting the variable valve mechanism 10 along the VI-VI straight line shown in FIG. In addition, the figure shown with a dashed-dotted line in FIG. 6 represents the cylinder head bearing 69 for fixing the variable valve mechanism 10 to a cylinder head.

  As shown in FIG. 6, the swing cam arms 26a and 26b are provided with holding holes 70a and 70b for holding the connection adjusting pin 30, respectively. The connection adjusting pin 30 passes through the through hole 44 of the holding hole 70b slide arm 42, and is inserted into the holding holes 70a and 70b at both ends thereof.

  A holding hole 70b provided in one swing cam arm 26b is a closed end. For this reason, the connection adjustment pin 30 does not fall off from the holding hole 70b side. The other holding hole 70a is an open end. The cylinder head bearing 69 is designed not to close the holding hole 70a at the open end when the variable valve mechanism 10 is assembled to the cylinder head. For this reason, the connection adjusting pin 30 can be easily attached / detached from the holding hole 70a side even after the variable valve mechanism 10 is once assembled.

FIG. 7 is an enlarged view of the connection adjusting pin 30 used in the present embodiment. The connection adjusting pin 30 has a large diameter portion 72 to be inserted into the holding hole 70b and the through hole 44, and a small diameter portion 74 to be extended into the holding hole 70a. In the present embodiment, the two holding holes 70a and 70b and the through hole 44 are processed to have the same diameter. The large-diameter portion 72 of the connecting adjustment pin 30, the diameter D _L is given as the relationship fitting for the diameter is established. On the other hand, the small-diameter portion 74, the diameter D _L or less of the small-diameter D _S is given.

Hereinafter, the description will be continued with reference to FIG. 6 again. The relative position of the swing cam arm 26b and the slide arm 42 is uniquely determined by inserting the connection adjusting pin 30. In contrast, the other for the swing cam arm 26a, since the diameter of the holding hole 70a is equal to or greater than the diameter D _S of the connecting adjustment pin 30, the only connection adjustment pin 30 is inserted, device with respect to the slide arm 42 The position is not uniquely determined.

  However, the swing cam arm 26a receives the urging force of the valve spring 20a via the rocker arm 16a when mounted on the internal combustion engine (see FIG. 2). This urging force, that is, the valve spring force, acts as a force for rotating the swing arm 26a around the control shaft 28. As a result, the position of the swing arm 26a is such that the inner wall of the holding portion 70a is smaller The position is determined to interfere (contact) with the portion 74.

FIG. 8 is a diagram for explaining in more detail how the position of the swing cam arm 26a is determined by the valve spring force. More specifically, FIG. 8 is a diagram showing the swing cam arm 26a in a side view when mounted on the internal combustion engine. Swing cam arm 26a, when the arm rotation angle theta _A is smaller than a predetermined value, starts to push the rocker arm 16a by the pressing portion 34a (see FIGS. 2 and 5). At that time, the swinging cam arm 26a receives the input of the valve spring force at the pressing portion 34a.

  The valve spring force acting on the pressing portion 34a acts as a torque for rotating the swing cam arm 26a in the clockwise direction in FIG. Since the connection adjustment pin 30 is fixed to the control shaft 28, the torque acts as a force for rotating the swing cam arm 26 a relative to the connection adjustment pin 30 in the clockwise direction. As a result, the swing cam arm 26a rotates until the inner wall of the holding portion 70a contacts the connection adjusting pin 30 (the small diameter portion 72 thereof), and is substantially fixed at a position where the contact occurs.

A force in a direction to release the contact between the holding portion 70a and the connection adjusting pin 30 does not act on the swing cam arm 26a. Therefore, when the variable valve mechanism 10 is mounted on an internal combustion engine, the diameter of the holding portion 70a is, even more than the diameter D _S of the small diameter portion 74 which is retained therein, the position of the swing cam arm 26a Is in a substantially fixed state.

[Adjustment method of variable valve mechanism]
As described above, the variable valve mechanism 10 of the present embodiment is configured so that the connection adjusting pin 30 can be attached and detached from the holding hole 70a side even after being mounted on the internal combustion engine. Then, in the state in the present embodiment, as described below, in advance to prepare the diameter D coupling adjustment pin 30 of a plurality ranks different _S of the small diameter portion 74 in advance, provided with a variable valve mechanism 10 in an internal combustion engine, Both the valve opening characteristics of the two valve bodies 12a and 12b are properly adjusted by repeating the attachment / detachment of the connection adjusting pin 30 as necessary.

FIG. 9 is a diagram for explaining an example of a relative positional relationship established between the swing cam arms 26a and 26b in a state where the variable valve mechanism 10 is mounted on the internal combustion engine. More specifically, FIG. 9, the diameter of the swing cam arm 26a generating no dimensional deviation, with respect to 26b, the diameter D _S is the smallest rank of the small-diameter portion 74, i.e., the large diameter portion 74 and small diameter portion 72 The relative positional relationship is shown when the connection adjustment pin 30 having the rank that maximizes the difference (D _L −D _S ) is inserted.

In the state shown in FIG. 9, a positional deviation of ΔL occurs between the two swing cam arms 26a and 26b at the positions of the holding holes 70a and 70b. Further, due to the positional deviation of ΔL, there is an angular deviation of Δθ in the posture of the swing cam arms 26a, 26b. ΔL and Δθ increase as the difference in diameter between the large diameter portion 72 and the small diameter portion 74 (D _L −D _S ) of the connection adjusting pin 30 increases. Therefore, ΔL and Δθ shown in FIG. 9 are the maximum values that can occur in this embodiment. Hereinafter, ΔL and Δθ shown in FIG. 9 are referred to as “coupling pin adjustment allowance ΔL” and “operating angle adjustment allowance Δθ”, respectively.

In this embodiment, the connecting adjusting pin 30 of a plurality ranks according to the diameter D _S of the small diameter portion 74 is prepared. Specifically, rank and (D _L -D _S) ranks the maximum as in the case shown in FIG. 9 (hereinafter, referred to as "maximum rank") from approximately zero (D _L -D _S) Up to (hereinafter referred to as “minimum rank”), the connection adjusting pins 30 are prepared in a ranked state. The swing cam arm 26a rotates counterclockwise in FIG. 9 with respect to the other swing cam arm 26b as the rank of the coupling adjustment pin 30 decreases. Therefore, the relative positional relationship between the swing cam arms 26a and 26b shown in FIG. 9 is within the range of the connection pin adjustment allowance ΔL, that is, within the range of the working angle adjustment allowance Δθ by changing the rank of the connection adjustment pin 30. It can be adjusted arbitrarily.

  The valve opening characteristics (lift amount and working angle) of the valve bodies 12a and 12b can be made uniform by setting the relative positional relationship of the swing cam arms 26a and 26b to an appropriate relationship. As long as the variable valve mechanism 10 is processed and assembled within a tolerance, the variable valve mechanism 10 is designed so that an appropriate relationship falls within the range of the operating angle adjustment allowance Δθ. For this reason, according to the variable valve mechanism 10, the valve opening characteristics of the two valve bodies 12a and 12b are accurately determined by selecting an appropriate one from the connection adjustment pins 30 prepared in advance and using it for assembly. It is possible to arrange well.

  Specifically, for example, the valve opening characteristics of the two valve bodies 12a and 12b can be made uniform by assembling in the following procedure. That is, first, the variable valve mechanism 10 is assembled using the connection adjustment pin 12 of the reference rank, and the variable valve mechanism 10 is mounted on the internal combustion engine. Next, the valve opening characteristics of the two valve bodies 12a and 12b are measured to detect how much deviation has occurred between them.

  If there is no significant deviation in the valve opening characteristics, the assembly of the variable valve mechanism 10 is terminated at that time. On the other hand, when a significant deviation is recognized in the valve opening characteristic, the rank of the connection adjusting pin 30 for absorbing the deviation is selected according to a predetermined rule. Next, the connection adjustment pin 30 is changed to that of the selected rank, and the assembly operation of the variable valve mechanism 10 is completed. In addition, when necessity is recognized, after exchanging the connection adjustment pin 30, the valve opening characteristics of the valve bodies 12a and 12b may be compared again, and finer correction may be repeated.

[Effect of Embodiment 1]
As described above, according to the configuration and the adjustment method used in the present embodiment, by changing the rank of the connection adjustment pin 30, the valve opening characteristic of one valve element 12a is changed to the valve opening characteristic of the other valve element 12b. Can be adjusted independently. For this reason, according to the variable valve mechanism 10 of this embodiment, it is desired for each of the two valve bodies 12a and 12b without requiring high processing accuracy and assembly accuracy for each component. The valve opening characteristics can be provided.

  Further, according to the variable valve mechanism 10 of the present embodiment, even when the valve opening characteristics of the two valve bodies 12a and 12b show different temporal changes, it is only necessary to replace the connection adjusting pin 30 to The valve opening characteristics can be easily aligned. Therefore, according to the configuration and adjustment method of the present embodiment, it is possible to have excellent productivity and excellent maintainability, and to drive a plurality of valve bodies with desired valve opening characteristics with high accuracy. The variable valve mechanism 10 can be realized.

  Furthermore, since the variable valve mechanism 10 of the present embodiment is configured to hold the small diameter portion 74 of the connection adjusting pin 30 in the holding hole 70a serving as the open end, the following effects can also be achieved. it can. FIG. 10 is a diagram for explaining the contents of the effects associated with the above configuration. More specifically, FIG. 10 is a cross-sectional view showing the periphery of the connection adjusting pin 30 in an environment mounted on the internal combustion engine.

  The swing cam arm 26a is maintained in a state in which the inner wall of the holding hole 70a is in contact with the connection adjusting pin 30 by receiving a valve spring force in an environment where the swing cam arm 26a is mounted on the internal combustion engine. At this time, the inner wall of the swing cam arm 26a comes into contact with the small diameter portion 74 of the connection adjusting pin 30, as shown in FIG. As long as the swing cam arm 26a is in the state shown in FIG. 10, the axial movement of the connection adjusting pin 30 is restricted by the swing cam arm 26a. That is, in this case, the side wall of the swing cam arm 26a functions as a stopper with respect to the step formed between the large diameter portion 72 and the small diameter portion 74, and the axial movement of the connection adjusting pin 30 is restricted. .

  Therefore, according to the configuration of the present embodiment, the connection adjustment on the internal combustion engine can be performed without providing any special structure while the one holding hole 70a that holds the end of the connection adjustment pin 30 is an open end. The pin 30 can be reliably prevented from falling off. In this respect, the variable valve mechanism 10 of the present embodiment is excellent in productivity and maintainability and is suitable for realization at a low cost.

[Modifications, etc.]
Incidentally, the variable valve mechanism 10 of the first embodiment described above, only the swing cam arm 26a, although the varying the the diameter of the retaining hole 70a and the diameter D _S of the connecting adjustment pin 30, its configuration is this It is not limited to. That is, the relative positional relationship between the holding hole and the connection adjusting pin 30 is uniquely determined after receiving the valve spring force even if there is a difference between the diameters of the two. For this reason, it is good also as giving the diameter more than the diameter of the connection adjustment pin 30 with respect to the holding hole 70b also on the rocking cam arm 26b side.

  In the first embodiment described above, the two swing cam arms 26a and 26b have the holding holes 70a and 70b having the same diameter, but the diameters are not necessarily the same. Further, here, the diameter of the connection adjusting pin 30 is determined to be the maximum in the portion held by the holding portion 26b or the through hole 44 at the closed end, but this point is also limited to such a configuration. Is not to be done. That is, the swing cam arm 26a may be formed with a holding hole 70a having a larger diameter than the holding hole 70b of the swing cam arm 26b, and the connection adjusting pin 30 is held by the large diameter holding hole 70a. The part may be configured to have a larger diameter than the part held in the other holding hole 70b.

In the first embodiment described above, the coupling adjustment pin 30, by changing the diameter D _S of the small diameter portion 74, the valve body 12a, although the adjusting the opening characteristics of the 12b, the adjustment method However, the present invention is not limited to this. That is, the same adjustment function may be realized by changing the diameter of the holding hole 70a or 70b while keeping the diameter of the connection adjustment pin 30 constant.

It is a perspective view of the variable valve mechanism of Embodiment 1 of this invention. It is the figure showing the vicinity of a valve body and a rocker arm from the II arrow direction shown in FIG. 1 is an exploded perspective view of a swing range variable mechanism and a cam included in a variable valve mechanism according to Embodiment 1 of the present invention. It is the top view and side view of the variable valve mechanism of Embodiment 1 of this invention. Sectional drawing obtained by cut | disconnecting the variable valve mechanism of Embodiment 1 of this invention along the VV straight line shown in FIG. 4 (A) is shown. Sectional drawing obtained by cut | disconnecting the variable valve mechanism of Embodiment 1 of this invention along the VI-VI straight line shown in FIG.4 (B) is shown. It is an enlarged view of the connection adjustment pin used in Embodiment 1 of this invention. It is a figure for demonstrating a mode that the position of a rocking cam arm is determined by valve spring force in Embodiment 1 of this invention. It is a figure for demonstrating an example of the relative positional relationship formed between two rocking cam arms in the state in which the variable valve mechanism of Embodiment 1 of this invention was mounted in the internal combustion engine. It is a figure for demonstrating the drop prevention effect of the connection adjustment pin obtained by the structure of Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Variable valve mechanism 12a, 12b Valve body 16a Rocker arm 20a Valve spring 26a, 26b Oscillation cam arm 28 Control shaft 30 Connection adjustment pin 36 Oscillation range variable mechanism 38 Cam 42 Slide arm 50 Roller slide part 52 Control arm 54 Intermediate arm 64 Rotating shaft 66 Contact roller 68 Slide roller 69 Cylinder head bearings 70a, 70b Holding hole 72 Large diameter portion 74 Small diameter portion θ _C Control shaft rotation angle θ _A Arm rotation angle ΔL Connection pin adjustment allowance Δθ Working angle adjustment allowance

Claims (6)

A swing range variable mechanism that swings in synchronization with the rotation of the cam of the internal combustion engine and changes the swing range according to the position of the control shaft;
A connection adjusting pin held by the swing range variable mechanism;
A plurality of swing cam arms each having a holding hole for holding the connection adjusting pin, and being connected to the swing range variable mechanism by inserting the connection adjusting pin into the holding hole;
A valve body provided corresponding to each of the swing cam arms and opened by being biased by each swing cam arm;
A valve spring that biases the swing cam arm in a direction to close the valve body;
The variable valve mechanism for an internal combustion engine, wherein at least one of the plurality of swing cam arms has a diameter of the connection adjusting pin at a portion held by the holding hole smaller than a diameter of the holding hole. . The holding holes provided in the plurality of swing cam arms have the same diameter,
2. The variable valve mechanism for an internal combustion engine according to claim 1, wherein the connection adjusting pins have different diameters at portions held in the respective holding holes. The holding hole for holding one end of the connection adjustment pin is a non-through hole,
The holding hole for holding the other end of the connection adjusting pin is a through hole,
The variable valve mechanism for an internal combustion engine according to claim 2, wherein the connection adjusting pin has a portion inserted into the through hole having a smaller diameter than a portion adjacent to the portion.   The variable valve mechanism according to claim 1, wherein the holding holes provided in the plurality of swing cam arms have different diameters. A swing range variable mechanism that swings in synchronization with the rotation of the cam of the internal combustion engine and changes the swing range according to the position of the control shaft;
A connection adjusting pin held by the swing range variable mechanism;
A plurality of swing cam arms each having a holding hole for holding the connection adjusting pin, and being connected to the swing range variable mechanism by inserting the connection adjusting pin into the holding hole;
A valve body provided corresponding to each of the swing cam arms and opened by being biased by each swing cam arm;
An adjustment method for a variable valve mechanism of an internal combustion engine comprising a valve spring that biases the swing cam arm in a direction to close the valve body,
Preparing a plurality of ranks of coupling adjustment pins having different combinations of diameters of the portions respectively held by the holding holes of the plurality of swing cam arms;
Selecting an optimal connection adjusting pin from the plurality of ranks;
Assembling the selected connection adjusting pin to the plurality of swing cam arms and the swing range variable mechanism;
A method for adjusting a variable valve mechanism for an internal combustion engine, comprising: A swing range variable mechanism that swings in synchronization with the rotation of the cam of the internal combustion engine and changes the swing range according to the position of the control shaft;
A connection adjusting pin held by the swing range variable mechanism;
A plurality of swing cam arms each having a holding hole for holding the connection adjusting pin, and being connected to the swing range variable mechanism by inserting the connection adjusting pin into the holding hole;
A valve body provided corresponding to each of the swing cam arms and opened by being biased by each swing cam arm;
An adjustment method for a variable valve mechanism of an internal combustion engine comprising a valve spring that biases the swing cam arm in a direction to close the valve body,
Preparing a plurality of ranks of swing cam arms having different diameters of the holding holes;
Determining a reference swing cam arm as one of the plurality of swing cam arms;
For each of the remaining plurality of swing cam arms, selecting a swing cam arm that is optimally combined with the reference swing cam arm from the plurality of ranks;
Assembling the reference swing cam arm, the selected swing cam arm, the connection adjusting pin, and the swing range variable mechanism;
A method for adjusting a variable valve mechanism for an internal combustion engine, comprising:

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