JP2006144743A - Variable valve system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve system for an internal combustion engine improving mountability on the engine and durability of the system. <P>SOLUTION: A rocker arm mechanism 20 is provided with a third arm 25 transmitting rocking displacement of a second arm 22 to a first arm 21. The second arm has a fulcrum arranged on a position in an outside of outer diameter of a rocker shaft 16 as a fulcrum on the rocker shaft side, and is provided with an eccentric shaft member 82 of which position is changed by rotation of the rocker shaft and a connecting member 24 connecting the eccentric shaft and a rocker shaft. The connecting member includes a connection main body part 34 pivotally supporting the eccentric shaft member and a shaft part 44 extended from the connection main body part and locked on the rocker shaft under a condition passing through the rocker shaft. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine capable of continuously changing the lift characteristics of intake and exhaust system valves.

This type of variable valve device can continuously change the lift characteristics (drive phase and lift amount) of the intake and exhaust valves in accordance with the operating state of the internal combustion engine. Thereby, for example, in an automobile engine, acceleration of exhaust gas purification, reduction of fuel consumption, and the like are achieved.
In addition, there are various mechanisms such as switching a plurality of cams or using gears and springs in the device, but the complexity of this device makes it difficult to mount it on the engine. Has been disclosed (for example, see Patent Document 1).
JP 2004-150301 A

  By the way, in the variable valve operating apparatus described in Patent Document 1, the rocker shaft is provided with a connecting member having a spherical universal joint portion, and the second arm is swingable below the universal joint portion. Is fitted. Then, the rotation characteristic of the lift is changed by changing the rotation phase of the second arm relative to the cam by the rotation of the rocker shaft. However, since the dimensions of the parts of the universal joint portion may change from the initial values due to wear or the like, the second arm may be detached from the universal joint portion in this structure.

Therefore, it is conceivable to provide an eccentric shaft on the rocker shaft. Specifically, the axis of the eccentric shaft is decentered with respect to the axis of the rocker shaft within the range of the outer diameter of the rocker shaft, and the end of the eccentric shaft is provided in series with the end of the rocker shaft. The second arm is engaged with the eccentric shaft.
However, the lift characteristic in the structure is changed by changing the position of the eccentric shaft by rotating the rocker shaft. Therefore, in order to ensure the required rotation phase of the second arm with respect to the cam, the rocker shaft must have a large diameter or the amount of rotation of the rocker shaft must be increased. Is still left.

Further, in view of the fact that a large load is applied to the above-described variable valve device as the engine is driven, not only the above-described mountability but also the durability of the device must be satisfied at the same time.
The present invention has been made in view of such a problem, and an object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine capable of improving mountability to an engine and improving durability of the apparatus. .

  In order to achieve the above object, a variable valve operating apparatus for an internal combustion engine according to claim 1 is provided with a rocker arm mechanism that opens and closes an intake valve or an exhaust valve of the internal combustion engine, and a rocker arm that is rotatably provided in the internal combustion engine. A rocker shaft engaged with the mechanism, and a camshaft that is provided in the internal combustion engine so as to be rotatable and includes a cam that drives the rocker arm mechanism. By the rotation of the rocker shaft, the lift of the intake valve or the exhaust valve is increased. The rocker arm mechanism is a variable valve device capable of changing the characteristics, and the rocker arm mechanism swings about the axis of the rocker shaft as a fulcrum, and the cam side abuts the cam on the first arm that can drive the intake valve or the exhaust valve The second arm swinging around the rocker shaft side as a fulcrum, and the second arm and the first arm, respectively, and the swing displacement of the second arm is transmitted to the first arm. The second arm has a fulcrum disposed at a position outside the outer diameter of the rocker shaft as a fulcrum on the rocker shaft side, and is positioned by the rotation of the rocker shaft. An eccentric shaft member to be changed, a connecting member that connects the eccentric shaft member and the rocker shaft, the connecting member extending from the connecting main body portion, the connecting main body portion supporting the eccentric shaft member, and the rocker And a shaft portion locked to the rocker shaft in a state of penetrating the shaft.

According to a second aspect of the present invention, the second arm has a roller that contacts the cam on the cam side, and the cam that avoids interference with the cam between the roller and the eccentric shaft member. It is characterized in that a receiving part is provided.
According to a third aspect of the present invention, the second arm has an abutting flat surface portion in surface contact with the third arm, and the third arm has an converting flat surface portion in surface contact with the abutting flat surface portion. It is characterized by having.

  Therefore, according to the variable valve operating apparatus for an internal combustion engine of the first aspect of the present invention, the shaft center of the eccentric shaft member is not at a position inside the outer diameter of the rocker shaft but at a position outside the outer diameter. The eccentric amount is larger than the radius of the rocker shaft. Therefore, the rocker shaft side fulcrum with respect to the rocker shaft axis, that is, the eccentric amount to the axis of the second arm, without increasing the diameter of the rocker shaft or increasing the amount of rotation of the rocker shaft as in the prior art. Becomes larger. As a result, the required rotation phase of the second arm with respect to the cam can be ensured while reducing the size of the apparatus, which contributes to an improvement in mountability to the engine.

Further, since the eccentric shaft member is pivotally supported by the connecting member, it becomes difficult to come off due to wear or the like as compared with the conventional case. As a result, the reliability of the apparatus in terms of strength is also improved.
According to the second aspect of the present invention, since a part of the cam is accommodated in the cam receiving portion, the interference between the second arm and the cam is avoided. Therefore, the space in the vertical direction of the engine is small, and the mountability is further improved.

  Further, according to the invention described in claim 3, since the second arm and the third arm are brought into surface contact with each other at the abutting plane portion and the conversion plane portion, the arc surface and the arc surface or plane As compared with the transmission of load and displacement due to contact, the contact area is increased and the contact surface pressure is reduced. Accordingly, the reliability of the apparatus from the viewpoint of strength is further improved, and further, the space in the front-rear direction of the engine can be reduced. In this case, the mountability is further improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a variable valve gear 2 for an internal combustion engine according to this embodiment. As shown in the figure, the variable valve operating apparatus 2 is disposed in a cylinder head portion of an automobile engine, and drives an intake valve (not shown) via a rocker arm mechanism 20 to open and close an intake passage. The variable valve device 2 may drive the exhaust valve to open and close.

A camshaft 12 is rotatably provided in the cylinder head, and the rotation of the cam 10 is appropriately converted into a reciprocating swing of the rocker arm mechanism 20 according to the rotation of a crankshaft (not shown), and the camshaft 12 is The intake passage is opened by applying a downward force.
Further, a rocker shaft 16 is rotatably provided on the cylinder head, and the rocker shaft 16 and the camshaft 12 are disposed in parallel. The rocker shaft 16 and the rocker arm mechanism 20 are bolted to a portion protruding from the flat portion 18 as will be described later using a nut 19 and the rocker shaft 16 is rotated by a rotating means using a stepping motor or the like. Then, the lift characteristics (drive phase and lift amount) of the intake valve are continuously changed.

The rocker arm mechanism 20 according to the present embodiment includes three arms: a valve drive arm (first arm) 21, a characteristic adjustment arm (second arm) 22, and a displacement transmission arm (third arm) 23. Yes.
Specifically, as shown in FIG. 2, the valve drive arm 21 has a tip 31 that presses the intake valve. An adjustment screw 81 is provided at the distal end portion 31. The leading end 31 is connected to rear end portions 41 and 41 extending toward the displacement transmission arm 23, and the rocker shaft 16 is inserted between the leading end portion 31 and each rear end portion 41. The shaft fitting insertion parts 61 and 61 to be performed are provided. Thus, the valve drive arm 21 is swingably supported by the rocker shaft 16 and swings about the axis C1 of the rocker shaft 16 as a fulcrum to drive the intake valve. The rear end portions 41 and 41 are coupled by a stepped roller support shaft 71, and a contact roller 51 is provided on the roller support shaft 71, and the contact roller 51 contacts the displacement transmission arm 23. Is done.

  On the other hand, the characteristic adjustment arm 22 extends from the rocker shaft side toward the cam side, and swings about the rocker shaft side as a fulcrum when the cam side comes into contact with the cam 10. Specifically, as shown in FIG. 3, first, the rocker shaft side has swing support portions 32, 32 that are swingably supported by an eccentric pin (eccentric shaft member) 82. The part 32 is connected to the rear end parts 42 and 42 facing the cam side via the connection parts 72A and 72A. The rear end portions 42 are coupled by a roller support shaft 92, and the roller support shaft 92 is provided with a contact roller (roller) 62 that contacts the cam 10.

The contact roller 62 and the eccentric pin 82 are disposed in parallel, and between the contact roller 62 and the eccentric pin 82, in other words, the connection portions 72A and 72A, the contact roller 62, and the eccentric pin 82 are eccentric. A space portion surrounded by the pins 82 is formed as a lightening portion (cam receiving portion) 72.
Further, a connecting member 24 that connects the eccentric pin 82 and the rocker shaft 16 is provided between the swing support portions 32 and 32. More specifically, the connecting member 24 includes a connecting main body portion 34 and a fitting shaft portion (shaft portion) 44, and the fitting shaft portion 44 is directed from the connecting main body portion 34 toward the rocker shaft 16. The connecting shaft 24 is locked to the rocker shaft 16 by extending the distal end portion of the fitting shaft portion 44 through the rocker shaft 16 and screwing into the nut 19.

  On the other hand, the connection main body 34 pivotally supports the eccentric pin 82 between the swing support portions 32, 32. Therefore, the fulcrum on the rocker shaft side, that is, the shaft center C2 of the eccentric pin 82 pivotally supported by the connection main body portion 34 is relative to the shaft center C1 of the rocker shaft 16 penetrating the fitting shaft portion 44. It is arranged at a position outside the outer diameter of 16 and is eccentric. When the pivoting means pivots the rocker shaft 16, the eccentric pin 82 is displaced around the axis C <b> 1 of the rocker shaft 16. This displacement changes the rotation phase of the characteristic adjustment arm 22 with respect to the cam 10 to the retard side or the advance side. As a result, the lift characteristics of the intake valve are continuously changed.

Further, a contact portion 52 that contacts the displacement transmission arm 23 extends from each of the rear end portions 42 and 42 coupled by the roller support shaft 92, and the contact portion 52 includes a contact roller 62. The outer peripheral side of the outer peripheral side of the opposite side of the lightening portion 72 is covered. Further, the contact portion 52 includes a contact flat surface portion 102 that is in surface contact with the displacement transmission arm 23.
As described above, the displacement transmission arm 23 is in contact with the contact roller 51 of the valve drive arm 21 and the contact portion 52 of the characteristic adjustment arm 22, respectively, and swings around the support shaft 33 as a fulcrum, thereby adjusting the characteristics. The swing displacement of the arm 22 can be transmitted to the valve drive arm 21.

  Specifically, as shown in FIGS. 4 and 5, the displacement transmission arm 23 includes a conversion surface portion 43 and a non-conversion surface portion 53 that are in rolling contact with the contact roller 51. The conversion surface portion 43 is connected to rear end portions 73, 73 extending rearward, that is, toward a return spring (not shown), and is supported between the conversion surface portion 43 and each rear end portion 73. Support shaft fitting insertion portions 83 and 83 that are inserted through the shaft 33 are provided. In the lower part of each support shaft insertion portion 83, a contact shaft portion 63 in contact with the contact portion 52 is rotatably supported using a bush 93. On the other hand, a spring receiving shaft portion 113 that is in contact with the return spring is rotatably supported by a bush 123 at the rear portion of each support shaft insertion portion 83.

  The contact shaft portion 63 is provided with a conversion flat surface portion 103 that is brought into surface contact with the contact flat surface portion 102. The contact roller 51 is provided on the conversion surface portion 43, and the contact portion 52 is provided on the contact shaft portion 63. The swinging displacement of the characteristic adjusting arm 22 is transmitted to the valve driving arm 21 at the positions where they are in contact with each other. On the other hand, even when the contact roller 51 is in contact with the non-conversion surface portion 53, the contact flat surface portion 102 of the contact portion 52 is in contact with the conversion flat portion 103 of the contact shaft portion 63. The swinging displacement of the adjustment arm 22 is canceled and is not transmitted to the valve drive arm 21. The spring receiving shaft portion 113 is also provided with a flat portion 133 that forms a flat portion downward and receives the spring force of the return spring. This spring force acts in a direction in which the conversion plane portion 103 is brought into contact with the contact plane portion 102. As a result, the displacement transmission arm 23 is biased in a direction to rotate around the counter hour hand with respect to the axis C3 of the support shaft 33.

Next, operation | movement of the variable valve apparatus 2 of this embodiment is demonstrated.
When the camshaft 12 is rotated around the counterclockwise hand as shown in the drawing at the most retarded side, that is, at the position of the eccentric pin 82 shown in FIG. 6, the characteristic adjusting arm 22 follows its cam curve. Swings with respect to the heart C2. Specifically, when the contact roller 62 is pushed up by contact with the cam nose portion 14, the characteristic adjustment arm 22 swings around the counterclockwise needle with respect to the axis C2. At the same time, the displacement transmitting arm 23 resists the urging force from the return spring and swings around the hour hand with respect to its axis C3. When the conversion surface portion 43 pushes out the contact roller 51, the valve drive arm 21 swings around the counterclockwise needle with respect to the axis C1 to drive the intake valve to open from the smaller rotation angle of the cam 10. .

  On the other hand, as shown in FIG. 7, when the eccentric pin 82 is largely rotated from the position shown in FIG. 6 around the counter hour hand by the rotation of the rocker shaft 16, as shown in FIG. The contact point between the contact roller 62 and the cam 10 moves around the hour hand on the cam curve, and at the same time, the characteristic adjustment arm 22 has a tip end portion of the contact flat portion 102 of the contact portion 52 of the contact shaft portion 63. It moves in a direction away from the conversion plane part 103. As a result, the displacement transmitting arm 23 swings around the counterclockwise needle with respect to the axis C3 by the urging force from the return spring, and the contact roller 51 is brought into contact with the non-converting surface portion 53. In this case, the camshaft 12 rotates about the counter hour hand as shown in the drawing, and the displacement transmission arm 23 swings about the hour hand, but the contact roller 51 is not rotated while the cam shaft 12 rotates once. Since it does not go out of the range of the conversion surface portion 53, the valve drive arm 21 does not swing, and the lift amount of the intake valve becomes substantially zero and enters a resting state. In addition, since the characteristic adjustment arm 22 at this time approaches the camshaft 12, there is a possibility that interference with the cam nose part 14 may occur. In addition, the structure can be made compact.

  Thus, in the variable valve operating apparatus 2 of the present embodiment, the lift characteristics (drive phase and lift amount) of the intake valve can be continuously changed according to the rotation ratio of the rocker arm 16. When the lift characteristics require a high intake amount with a high rotation and a high load, when the low intake amount with a low rotation and a low load is required on the retard side, the activity of the exhaust gas aftertreatment device When it is desired to increase the exhaust gas temperature by reducing the intake air amount for the purpose of conversion, the automobile engine can achieve exhaust gas purification promotion, fuel consumption reduction, etc. by changing to the advance side.

  As described above, in the present embodiment, the axis C2 of the eccentric pin 82 is disposed not at a position inside the outer diameter of the rocker shaft 16, but at a position outside the outer diameter of the rocker shaft 16. The eccentric amount of the shaft center C2 of the eccentric pin 82 with respect to the shaft center C1 of the rocker shaft 16 is formed larger than the radius of the rocker shaft 16. That is, a large amount of eccentricity can be obtained without increasing the diameter of the rocker shaft or increasing the amount of rotation of the rocker shaft as in the prior art. Therefore, the weight of the rocker shaft 16 is reduced, and the operation amount of the rotating means is also reduced. As a result, a compact variable valve operating device 2 is achieved, and the required rotation phase of the characteristic adjusting arm 22 with respect to the cam 10 can be ensured, so that the mountability to an automobile engine is greatly improved.

Further, since the eccentric pin 82 is pivotally supported by the connecting member 24, it is less likely to come off due to wear or the like as compared with the conventional case. Therefore, the durability of the variable valve apparatus 2 is also improved.
Further, in the advanced state, the cam nose portion 14 and the characteristic adjustment arm 22 are close to each other, so there is a problem of interference. However, since the cam nose portion 14 is configured to be housed in the lightening portion 72, the characteristic adjustment arm 22 Interference with the cam 10 is avoided. Therefore, it is not necessary to provide a measure for avoiding this interference, for example, a space below the cam 10 or a space for allowing the displacement transmission arm 23 to escape upward. Therefore, the mountability is further improved.

  Furthermore, the characteristic adjusting arm 22 and the displacement transmitting arm 23 are brought into surface contact with each other by the contact flat surface portion 102 and the conversion flat surface portion 103. Therefore, the contact area is increased and the contact surface pressure is reduced as compared with the transmission of load or displacement due to contact between the arc surface and the arc surface or contact between the arc surface and the flat surface. Therefore, for example, the crash limit rotation speed of the valve system can be set high, and the durability of the variable valve apparatus 2 is further improved. In addition, for example, the width of the contact portion 52 and the length of the contact shaft portion 63 may be small, and the space in the front-rear direction of the automobile engine can be reduced. To do.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the variable valve apparatus 2 in which the characteristic adjustment arm 22 swings with respect to the eccentric pin 82 is described. However, the present invention is not necessarily limited to this form, and a bolt is used instead of the pin. The variable valve device used may be used, and in this case as well, the mounting on the engine and the durability of the device can be improved in the same manner as described above.

1 is a schematic configuration diagram of a variable valve operating apparatus for an internal combustion engine according to an embodiment of the present invention. It is a perspective view of the 1st arm in the variable valve apparatus of FIG. It is a perspective view of the 2nd arm in the variable valve apparatus of FIG. It is a perspective view of the 3rd arm in the variable valve apparatus of FIG. It is a perspective view of the 3rd arm in the variable valve apparatus of FIG. It is a figure explaining the operation | movement in the variable valve apparatus of FIG. It is a figure explaining the operation | movement in the variable valve apparatus of FIG.

Explanation of symbols

2 Variable valve gear 10 Cam 12 Cam shaft 16 Rocker shaft 20 Rocker arm mechanism 21 Valve drive arm (first arm)
22 Characteristic adjustment arm (second arm)
23 Displacement transmission arm (third arm)
24 connecting member 34 connecting body 44 fitting shaft (shaft)
62 Contact roller (roller)
72 Meat extraction part (cam receiving part)
82 Eccentric pin (Eccentric shaft member)
102 Abutting plane part 103 Conversion plane part

Claims (3)

A rocker arm mechanism that opens and closes an intake valve or an exhaust valve of the internal combustion engine, a rocker shaft that is rotatably provided to the internal combustion engine, and that is engaged with the rocker arm mechanism, and a rocker shaft that is rotatably provided to the internal combustion engine. And a camshaft provided with a cam for driving the rocker arm mechanism, and a variable valve operating device capable of changing a lift characteristic of the intake valve or the exhaust valve by rotation of the rocker shaft,
The rocker arm mechanism swings about the axis of the rocker shaft as a fulcrum, and is driven by the first arm capable of driving the intake valve or the exhaust valve and the cam side being in contact with the cam. A second arm that swings about the second fulcrum, and a third arm that abuts on the second arm and the first arm, respectively, and transmits the swing displacement of the second arm to the first arm. Arm and
The second arm has a fulcrum disposed at a position outside the outer diameter of the rocker shaft as a fulcrum on the rocker shaft side, and an eccentric shaft whose position is changed by the rotation of the rocker shaft. A member, and a connecting member that connects the eccentric shaft member and the rocker shaft,
The connection member includes a connection main body portion that supports the eccentric shaft member, and a shaft portion that extends from the connection main body portion and is locked to the rocker shaft in a state of passing through the rocker shaft. A variable valve operating apparatus for an internal combustion engine characterized by the above.   The second arm has a roller that contacts the cam on the cam side, and a cam receiving portion that avoids interference with the cam is provided between the roller and the eccentric shaft member. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein   The second arm has an abutting plane part that makes surface contact with the third arm, and the third arm has a conversion plane part that makes surface contact with the corresponding tangential plane part. Item 3. The variable valve operating apparatus for an internal combustion engine according to Item 1 or 2.

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