JP2014043786A - Variable valve device for internal combustion engine - Google Patents

Abstract

An object of the present invention is to provide a variable valve system for an internal combustion engine that is miniaturized.
A large cam (C2) provided between two small cams (C1), a rocker arm (RR) that receives an action from the small cam and drives a valve (V), and the rocker arm An internal combustion engine comprising: a swing arm (10) coupled to the rocker arm so as to be relatively rotatable and receiving an action from the large cam; and a lost motion mechanism (20) supporting the swing arm Variable valve gear.
[Selection] Figure 1

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine.

  2. Description of the Related Art Some variable valve systems for internal combustion engines include small and large cams connected to a camshaft and different sizes, and first and second rocker arms that are driven by the small cam and the large cam, respectively. The first and second rocker arms are connected and separated from each other by the action of hydraulic pressure. The first and second rocker arms are supported by the rocker arm shaft in a swingable manner. Patent Document 1 discloses such a variable valve operating apparatus for an internal combustion engine.

  In addition, as a technique related to the present invention, Patent Document 2 discloses an example of a swing cam type variable valve gear.

JP 2008-75479 A JP 2008-115701 A

  Since the variable valve operating device for an internal combustion engine of Patent Document 1 includes cams of different sizes and a rocker arm driven by the cam, the position of the camshaft has to be changed, compared to a conventional valve operating device. And upsizing.

  Accordingly, an object of the present invention is to provide a variable valve operating device for an internal combustion engine that is miniaturized.

  The object is to provide a large cam provided between two small cams, a rocker arm that receives an action from the small cam to drive a valve, and a rocker arm that is rotatable relative to the rocker arm. This can be achieved by a variable valve operating apparatus for an internal combustion engine that includes a swing arm that is coupled and receives an action from the large cam, and a lost motion mechanism that supports the swing arm.

  A variable valve operating apparatus for an internal combustion engine that is downsized can be provided.

FIG. 1 is an external view of the variable valve operating apparatus of the present embodiment. FIG. 2 is a diagram schematically showing a small cam and a rocker arm when viewed from the direction of arrow A in FIG. FIG. 3 is a diagram schematically showing the large cam, the swing arm, and the lost motion mechanism when viewed from the direction of arrow A in FIG. FIG. 4 is a cross-sectional view taken along the line BB in FIGS. FIG. 5 is a diagram showing the relationship between the rotation angle of the camshaft and the lift amount of the small cam and the large cam. FIG. 6 is a cross-sectional view of the lost motion mechanism. FIG. 7 is a cross-sectional view of the lost motion mechanism at the time of locking. FIG. 8 is a view showing the operation of the variable valve operating apparatus when the valve is lifted by the cam profile of the small cam. FIG. 9 is a view showing the operation of the variable valve operating apparatus when the valve is lifted with the cam profile of the large cam.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIG. 1 is an external view of a variable valve apparatus 1 of the present embodiment. The variable valve operating apparatus 1 is employed in an internal combustion engine mounted on a vehicle or the like. The variable valve gear 1 lifts the valve V through a rocker arm RR described later by the rotation of the camshaft S. The variable valve gear 1 lifts two valves V per cylinder of the internal combustion engine. Hereinafter, the configuration of the variable valve gear 1 provided per cylinder of the internal combustion engine will be described. The valve V is an intake valve or an exhaust valve.

  The variable valve operating apparatus 1 includes a small cam C1, a rocker arm RR, a large cam C2, a swing arm 10, and a lost motion mechanism 20. The variable valve operating apparatus 1 includes two small cams C1 and two rocker arms RR. FIG. 2 is a diagram schematically showing the small cam C1 and the rocker arm RR when viewed from the direction of arrow A in FIG. FIG. 3 is a diagram schematically showing the large cam C2, the swing arm 10, and the lost motion mechanism 20 when viewed from the direction of arrow A in FIG. FIG. 4 is a view showing a BB plane in FIGS. 2 and 3.

  As shown in FIGS. 1 and 4, the two small cams C1 and the large cam C2 are fixed to the camshaft S with a predetermined interval. The large cam C2 is located between the two small cams C1. The small cam C1 and the large cam C2 rotate together with the camshaft S. FIG. 5 is a diagram of cam profiles of the small cam C1 and the large cam C2. As shown in FIG. 5, the cam lift and cam working angle of the large cam C2 are larger than the cam lift and cam working angle of the small cam C1. Furthermore, the valve closing timing of the large cam C2 and the valve closing timing of the small cam C1 are the same. Further, the buffer section on the valve closing side of the large cam C2 and the buffer section on the valve closing side of the small cam C1 are the same. In a section other than the valve closing timing, the cam profile of the large cam C2 draws the outside of the cam profile of the small cam C1. That is, in a section other than the valve closing time, the lift amount by the large cam C2 is larger than the lift amount by the small cam C1.

  As shown in FIG. 2, one end of the rocker arm RR is supported by a hydraulic lash adjuster RA. The rocker arm RR and the small cam C1 are in contact with each other by the action of the lash adjuster RA. The other end of the rocker arm RR presses the proximal end of the valve V. The lash adjuster RA may be an external oil supply type lash adjuster using engine oil or a sealed lash adjuster in which hydraulic oil is sealed. The lash adjuster RA is swingably supported with one end of the rocker arm RR as a fulcrum. The lash adjuster RA is disposed at the upper part of the cylinder head.

  As described above, the rocker arm RR is rotatable with one end of the lash adjuster RA as a fulcrum. The rocker arm RR is pressed by the nose portion of the small cam C1 and rotates to press the valve V. The valve V is opened by being pressed by the rocker arm RR. The configurations of the small cam C1, the rocker arm RR, and the lash adjuster RA are the same as those of a conventional valve operating device, that is, a valve operating device in which the operation of the valve V is not variable. Further, the small cams C1 and the rocker arms RR provided in the variable valve operating apparatus 2 by two have the same configuration.

  The swing arm 10 is connected to the rocker arm RR at one end by a connecting pin P. The swing arm 10 is positioned so as to be sandwiched between the two rocker arms RR. The connecting pin P connects the two rocker arms RR and the swing arm 10. The swing arm 10 can rotate relative to the rocker arm RR about the connecting pin P. The swing arm 10 is supported by the lost motion mechanism 20 in the supported portion 11. The supported portion 11 is located at the end away from the connecting pin P. The large cam C2 is in contact with the central portion of the swing arm 10. As the large cam C2 rotates, the nose portion of the large cam C2 presses the swing arm 10. The swing arm 10 is operated by being pressed by the nose portion of the large cam C2. The operation of the swing arm 10 when pressed from the large cam C2 is either an operation using the connecting pin P as a fulcrum or an operation using the supported portion 11 as a fulcrum. The operation of the swing arm 10 is switched depending on the state of the lost motion mechanism 20. Details of this operation will be described later.

  Next, the lost motion mechanism 20 will be described in detail. FIG. 6 is a sectional view of the lost motion mechanism 20. The lost motion mechanism 20 includes a head portion 21, a body portion 22, a head spring 23, a lock pin 24, and a pin spring 25.

  The head portion 21 contacts the supported portion 11 of the swing arm 10. The head portion 21 is assembled so as to be slidable in the direction indicated by the arrow D in FIG. 6 along the body portion 22. That is, the head portion 21 is a sliding component that comes into contact with the supported portion 11. The head spring 23 biases the head portion 21 toward the swing arm 10 side. The body part 22 is fixed to the cylinder head. A passage 26 through which oil passes is provided inside the body portion 22. Oil is supplied to the passage 26 from the cylinder head. The outlet portion 26 a of the passage 26 is provided on the side surface of the body portion 22. A concave portion 21 a is formed on the inner side surface of the head portion 21 at a position corresponding to the outlet portion 26 a of the passage 26. The lock pin 24 is provided at the outlet portion 26a. The oil pressure of the oil supplied into the passage 26 is controlled by an actuator (not shown) such as an oil control valve or a solenoid valve, for example. When the hydraulic pressure in the passage 26 rises, as shown in FIG. 7, a part of the lock pin 24 protrudes into the recess 21a, and the operation of the head portion 21 is locked. On the contrary, when the hydraulic pressure in the passage 26 decreases, the lock pin 24 is accommodated in the body portion 22 by receiving the restoring force of the pin spring 25. Thereby, the head portion 21 is slidable, that is, the lock is released. The mounting load of the head spring 23 is set smaller than the mounting load of the valve spring. For this reason, the valve V is not lifted by the restoring force of the head spring 23.

  Next, the lift of the valve V by the variable valve gear 1 will be described. The variable valve operating apparatus 1 can switch between the case where the valve V is lifted by the cam profile of the small cam C1 and the case where the valve V is lifted by the cam profile of the large cam C2. First, the case where the valve V is lifted with the cam profile of the small cam C1 will be described. FIG. 8 is a view showing the operation of the variable valve gear 1 when the valve V is lifted by the cam profile of the small cam C1. The umbrella part of the valve V drawn by a dotted line in FIG. 8 indicates the position of the umbrella part when the valve V is not lifted.

  Since the valve V operates by being pressed by the rocker arm RR, the lift of the valve V is determined by the operation of the rocker arm RR. Therefore, attention is paid to the operation of the rocker arm RR. The rocker arm RR receives a force directly from the small cam C1 and operates by receiving a force from the large cam C2 via the swing arm 10 and the connecting pin P. First, the operation received by the rocker arm RR from the small cam C1 will be described. When receiving a force from the small cam C1, the rocker arm RR rotates around the lash adjuster RA. As a result, the contact portion with the connecting pin P and the valve V moves in proportion to the length of the rocker arm RR.

  Next, the operation from the large cam C2 on the rocker arm RR will be described. When the valve V is lifted by the cam profile of the small cam C1, the lock in the lost motion mechanism 20 is released. Thereby, since the supported portion 11 is swingably supported by the lost motion mechanism 20, the supported portion 11 can freely swing. When the swing arm 10 is pressed by the large cam C <b> 2 while the lost motion mechanism 20 is unlocked, the supported portion 11 moves together with the head portion 21. At this time, the swing arm 10 rotates with the connecting pin P as a fulcrum and the supported portion 11 as an action point. That is, since the force of the large cam C2 does not act on the connecting pin P, the operation that acts on the rocker arm RR from the large cam C2 has a lost motion. Thus, since the operation from the large cam C2 has a lost motion, the rocker arm RR performs only the operation by the action from the small cam C1. As a result, the valve V is lifted by the cam profile of the small cam C1. As described above, since the connection pin P is operated by the action of the small cam C1, the movement of the swing arm 10 is a combination of the rotation about the connection pin P and the rotation about the lash adjuster RA. Perform the operation.

  In the state where the lost motion mechanism 20 is unlocked, the supported portion 11 follows the swing arm 10 by the restoring force of the head spring 23. That is, the lost motion mechanism 20 functions as a lash adjuster that fills the clearance between the large cam C <b> 2 and the swing arm 10 by the restoring force of the head spring 23.

  Next, the case where the valve V is lifted with the cam profile of the large cam C2 will be described. FIG. 9 is a view showing the operation of the variable valve gear 1 when the valve V is lifted by the cam profile of the large cam C2. The umbrella part of the valve V drawn by a dotted line in FIG. 9 indicates the position of the umbrella part when the valve V is not lifted.

  The lost motion mechanism 20 supports the supported portion 11 as a rotation fulcrum of the swing arm 10 when the valve V operates with the cam profile of the large cam C2. Specifically, when the valve V operates with the cam profile of the large cam C <b> 2, the lost motion mechanism 20 locks the head portion 21. As a result, the supported portion 11 is fixed by the lost motion mechanism 20. When the swing arm 10 receives a force from the large cam C2 while the supported portion 11 is fixed, the swing arm 10 operates with the supported portion 11 as a fulcrum. As a result, the connecting pin P moves in proportion to the arm length of the swing arm 10. As the connecting pin P moves, the rocker arm RR rotates around the lash adjuster RA, so that the valve V operates.

  By the way, the distance from the supported portion 11 serving as the fulcrum of the swing arm 10 to the connecting pin P is larger than the distance from the lash adjuster RA to the connecting pin P in the rocker arm RR. Furthermore, the lift amount of the large cam C2 is larger than the lift amount of the small cam C1. For this reason, the distance that the connecting pin P moves when the swing arm 10 receives a force from the large cam C2 is larger than the distance that the connecting pin P moves when the rocker arm RR receives a force from the small cam C1. growing. As a result, when the large cam C2 is operated, the distance by which the rocker arm RR rotates is larger than when the small cam C1 is operated. For this reason, when the rocker arm RR receives the action of the large cam C2, the lift amount of the valve V becomes larger than when only the action of the small cam C1 is received. Therefore, when operating with the cam profile of the large cam C2, the valve V operates with a large lift. Further, since the operating angle of the large cam C2 is larger than that of the small cam C1, when operating with the cam profile of the large cam C2, the operating angle of the valve V becomes large.

  As shown in FIG. 5, according to the cam profiles of the large cam C2 and the small cam C1, the lift period of the small cam C1 is included in the lift period of the large cam C2. Since the amount of movement of the connecting pin P increases during the operation of the large cam C2, the small cam C1 moves away from the rocker arm RR during the lift period of the large cam C2, as shown in FIG. As a result, during the operation of the large cam C2, the operation of the small cam C1 does not act on the rocker arm RR. However, in the buffer section on the closed side, the lift amounts of the large cam C2 and the small cam C1 coincide with each other, so that the rocker arm RR and the small cam C1 come into contact again. In the buffer section on the closing side, the valve V is seated in the same manner as when only the small cam C1 is operated.

  From the above, the variable valve apparatus 1 lifts the valve V with the cam profile of the small cam C1 by swinging and supporting the supported portion 11 and performing the lost motion of the operation by the large cam C2. Further, the variable valve operating apparatus 1 lifts the valve V with the cam profile of the large cam C2 by fixedly supporting the supported portion 11 and transmitting the operation by the large cam C2 to the rocker arm RR. Thus, the variable valve gear 1 makes the lift of the valve V variable.

  The variable valve operating apparatus 1 according to the present embodiment includes two sets of a small cam C1, a rocker arm RR, a large cam C2, a swing arm 10, and a lost motion mechanism 20. Normally, devices that have different sized cams and change the valve lift need to change the position of the camshaft, so the cylinder head and its peripheral parts used in conventional valve gears are shared. It cannot be used. However, the valve gear composed of the small cam C1 and the rocker arm RR of the present embodiment uses the same configuration as the conventional valve gear. Thus, the variable valve operating apparatus 1 of the present embodiment can divert components of a conventional internal combustion engine. Further, since the position of the camshaft S is the same as that of the conventional valve gear, other parts and structures of the internal combustion engine such as a cylinder head can be used as they are. Thereby, an internal combustion engine provided with the variable valve operating apparatus 1 can reduce manufacturing cost.

  Moreover, a space is generated between the two small cams C1 due to the configuration of the valve operating device. In the variable valve operating apparatus 1 according to the present embodiment, the large cam C2 is disposed in the space between the two small cams C1 to effectively use the space. For this reason, the lift of the valve | bulb V can be changed, without enlarging apparatus itself. Therefore, it is possible to provide a variable valve operating device 1 for an internal combustion engine that is downsized. Furthermore, the variable valve apparatus 1 can prevent the occurrence of a lateral moment on the rocker arm RR by disposing the large cam C2 between the two small cams C1.

  By the way, as described above, when the valve V is driven by the profile of the large cam C2, the operation of the head portion 21 of the lost motion mechanism 20 is locked. In this case, a buffer function equivalent to the lash adjuster in the lost motion mechanism 20 cannot be expected. For this reason, in order to reduce the impact force when the valve is seated, it is required to design a large impact portion. However, if the height of the buffer portion is increased, the actual valve timing varies greatly, and the internal combustion engine It is possible that performance, fuel consumption, and emissions will deteriorate. In the variable valve operating apparatus 1 of the present embodiment, the valve closing timing of the large cam C2 and the valve closing timing of the small cam C1 are the same timing, and the buffer section on the valve closing side of the large cam C2 and the small cam C1 Since the buffer section on the valve closing side is the same, the valve is seated on the same lift curve as that of the small cam C1 even when operating with the profile of the large cam C2. For this reason, even when operating with the profile of the large cam C2, since the impact portion height is small, deterioration of the performance, fuel consumption and emission of the internal combustion engine can be suppressed.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 1 Variable valve operating apparatus 10 Swing arm 11 Supported part 20 Lost motion mechanism 21 Head part (sliding part)
24 Lock Pin 26 Passage C1 Small Cam C2 Large Cam RR Rocker Arm V Valve

Claims (4)

A large cam provided between two small cams,
A rocker arm that receives an action from the small cam and drives the valve;
A swing arm coupled to the rocker arm so as to be rotatable relative to the rocker arm, and receiving an action from the large cam;
A lost motion mechanism for supporting the swing arm;
A variable valve operating apparatus for an internal combustion engine comprising:   The lost motion mechanism supports a supported portion of the swing arm, and supports the supported portion in a swingable manner when the valve operates with a cam profile of the small cam, and the valve supports the large cam. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the supported portion is supported as a rotation fulcrum of the swing arm when the cam profile is operated. The lost motion mechanism is
A sliding part in contact with the supported part of the swing arm;
The variable valve operating apparatus for an internal combustion engine according to claim 2, further comprising: a lock pin that locks the operation of the sliding portion when the valve operates with the cam profile of the large cam. 4. The valve closing timing and closing timing buffer section of the large cam profile are the same as the valve closing timing and closing timing buffer section of the small cam profile, respectively. The variable valve operating apparatus for an internal combustion engine.

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