JP2008190392A - Variable valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve train capable of simplifying a structure of a rocker arm. <P>SOLUTION: This variable valve train 9 changes an opening-closing quantity of a valve 7 by operating the rocker arm 20 rockably interposed between a rotary cam 10 and the valve 7. Its rocker arm 20 is composed of an arm body 21 and a support member 26 arranged in a rocking center part of the rocker arm 20 and linearly and relatively displaceably supporting the arm body 21 in the pressing direction by the rotary cam 10. This variable valve train 9 changes the opening-closing quantity of the valve 7 by relatively indisplaceably connecting the arm body 21 and the support member 25 or releasing its connection by a switching mechanism 30. Its switching mechanism 30 comprises a connecting pin 31 displaceably arranged between a position for straddling B between the arm body 21 and the support member 26 and an unstraddled position, a hydraulic chamber 35 driving the connecting pin 31 by hydraulic pressure and arranged inside the support member 26, and an oil passage 36 supplying the hydraulic pressure to the hydraulic chamber 35. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism that changes an opening / closing amount of a valve in accordance with an operating state of an internal combustion engine.

  Some variable valve mechanisms change the open / close amount of the valve by operating a rocker arm interposed between the rotary cam and the valve so as to be swingable. Like the variable valve mechanism 80 of the first conventional example shown in FIG. 1A, the first rocker arm 83 and the second rocker arm 84 are arranged on the same shaft 81 so as to be swingable. , 84 are connected to each other so that they cannot be displaced relative to each other, and a connection release state in which the connection is released is changed (Patent Document 1) or FIG. Like the variable valve mechanism 90 of the second conventional example shown in FIG. 2B, a rocker arm 92 including an outer arm 93 provided on the outer side and an inner arm 94 provided on the inner side of the outer arm 93 is provided. Therefore, the opening / closing amount of the valve is changed by switching between a connection state in which the outer arm 93 and the inner arm 94 are connected to each other so as not to be relatively displaceable and a connection release state in which the connection is released (Patent Document). 2) etc. are known.

The switching will be described in more detail. In the switching mechanism 86 of the first conventional example, the connecting pin 87 is moved by a hydraulic pin driving mechanism 88 provided outside the first and second rocker arms 83 and 84. The hydraulic mechanism provided outside the rocker arm 92 also in the switching mechanism 96 of the conventional example 2 is driven between a position straddling between the first rocker arm 83 and the second rocker arm 84 and a position not straddling. The switching is performed by driving the connecting pin 97 between a position straddling between the outer arm 93 and the inner arm 94 and a position not straddling by the pin driving mechanism 98 such as the above.
JP 2006-132378 A US Patent Application Publication No. 2005/132990

  However, since the rocker arm of the first conventional example requires two of the first rocker arm 83 and the second rocker arm 84, the rocker arm 92 of the second conventional example has an arm composed of an outer arm 93 and an inner arm 94. Therefore, the number of parts increases and the structure of the rocker arm becomes complicated.

  Also, in both conventional switching mechanisms 86 and 96, pin driving mechanisms 88 and 98 for driving the connecting pins 87 and 97 are separately required outside the rocker arm. 96 are complicated.

  Therefore, the first object is to simplify the structure of the rocker arm, and the second object is to simplify the structure of the switching mechanism.

  In order to achieve the first object, the variable valve mechanism according to the present invention can change the opening / closing amount of the valve by operating a rocker arm that is swingably interposed between the rotary cam and the valve. In the variable valve mechanism, the rocker arm is provided at the rotary cam and the arm main body that contacts the valve, and at the rocking center of the rocker arm, and the arm main body can be linearly displaced in the pressing direction by the rotary cam. The arm body and the support member are connected to each other so that the relative displacement is impossible, and the connection is released to enable the relative displacement. A switching mechanism for switching between the connected and released states, and the opening / closing amount of the valve is changed by the switching.

  The change in the opening / closing amount of the valve here is not particularly limited, but switching is performed between a driving state in which the valve is driven according to the rotation of the rotating cam and a driving stop state in which the driving is completely stopped. Another example is a case of switching between a high lift state in which the valve is opened and closed with a relatively large lift amount and a low lift state in which the valve is opened and closed with a relatively small lift amount according to the rotation of the rotating cam.

  Although the rocker arm is not particularly limited, the rocker arm is provided with the rocking center portion at the base end portion, the rotation cam abutting on the lengthwise intermediate portion, and the valve abutting on the tip portion, or the lengthwise intermediate portion. As an example, there may be provided the above-mentioned rocking center portion, the rotating cam abutting on the rear end portion, and the valve abutting on the tip end portion.

  In order to achieve the second object, the switching mechanism includes a connecting pin provided to be displaceable between a position straddling between the arm main body and the support member and a position not straddling, and the connecting pin. It is preferable to include a hydraulic chamber provided inside the support member and driven by hydraulic pressure, and an oil passage for supplying the hydraulic pressure to the hydraulic chamber. With this structure, it is not necessary to separately provide a pin driving mechanism for driving the connecting pin outside the rocker arm as in the first and second examples, and the structure of the switching mechanism can be simplified. is there. In addition, by collecting the components of the switching mechanism inside the support member that becomes the rocking center portion of the rocker arm in this way, the weight on the tip side of the rocker arm can be reduced to cope with high-speed rotation.

  The form of the variable valve mechanism at this time is not particularly limited, but the support member is attached to the tip of a hydraulic lash adjuster, and the oil passage is formed inside the lash adjuster and of the support member. An example is provided via the inside.

  According to the present invention, there is no need to provide two rocker arms as in the conventional example 1, and it is not necessary to make the rocker arm a double arm structure composed of an outer arm and an inner arm as in the conventional example 2. The structure of the rocker arm can be simplified.

  The variable valve mechanism 9 of the present invention changes the opening / closing amount of the valve 7 by operating a rocker arm 20 that is swingably interposed between the rotary cam 10 and the valve 7. The rocker arm 20 is provided at an arm main body 21 that abuts on the rotary cam 10 and the valve 7, and a rocking center portion of the rocker arm 20, and supports the arm main body 21 so as to be linearly displaceable in the pressing direction by the rotary cam 10. And the supporting member 26. The variable valve mechanism 9 includes a connection state in which the arm main body 21 and the support member 26 are connected to each other so that the relative displacement is impossible, and a connection release in which the connection is released to enable the relative displacement. A switching mechanism 30 that switches between states is provided, and the opening / closing amount of the valve 7 is changed by the switching.

  Specifically, the switching mechanism 30 includes a connecting pin 31 that is displaceable between a position between the arm main body 21 and the support member 26 that crosses B and a position that does not straddle, and the connecting pin 31 is hydraulically driven. The hydraulic chamber 35 is provided inside the support member 26, and an oil passage 36 that supplies hydraulic pressure to the hydraulic chamber 35.

  The variable valve mechanism 9 shown in FIGS. 1 to 3 of the present embodiment is a mechanism that intermittently changes the opening / closing amount of the valve in accordance with the operating state of the internal combustion engine. In this embodiment, the variable valve mechanism 9 is provided only for half of a plurality of cylinders (not shown), and more specifically, for each intake valve 7 for the half of the cylinders. Each is provided. The variable valve mechanism 9 operates by driving a rocker arm 20 that is swingably interposed between the valve 7 and the rotary cam 10, thereby driving the valve 7 according to the rotation of the rotary cam 10, and the driving thereof. Is switched to the drive stop state in which the operation is stopped.

  The rotary cam 10 is formed on a camshaft 10x that is rotationally driven as the internal combustion engine operates, and includes a base circle portion 11 that is a basic portion and a cam nose 12 that protrudes from the base circle portion 11. Has been. The rotating cam 10 is disposed above the rocker arm 20, and a cam surface 10 s that presses the input roller 24 of the rocker arm 20 is formed on the outer peripheral surface of the rotating cam 10.

  The rocker arm 20 is provided at an arm main body 21 that is in contact with the rotary cam 10 and the valve 7, and a rocking center portion of the rocker arm 20. The rocker arm 20 is linear in the pressing direction by the rotary cam 10 (with respect to the support member 26. And a support member 26 supported so as to be relatively displaceable linearly). Further, the variable valve mechanism 9 releases the connection so that the arm body 21 and the support member 26 are connected to each other so that the above-described relative displacement is impossible, and the relative displacement is possible. A switching mechanism 30 is provided for switching between the disconnected state and the switching between the driving state and the driving stop state.

  The arm main body 21 is a single bar-shaped member extending in a substantially horizontal direction, and includes a mounting hole 22 penetrating in a substantially vertical direction in which the support member 26 is inserted in the base end portion 21a, and is provided in the middle in the longitudinal direction. The part 21 c is provided with an input roller 24 that rotatably contacts the rotating cam 10, and the tip end part 21 b is provided with a curved output surface 23 that contacts the stem end 7 e of the valve 7.

  The support member 26 is swingably supported on an upper portion of a hydraulic lash adjuster 40 attached to the cylinder head 6. The support member 26 is inserted into a mounting hole 22 penetrating the base end portion 21a of the arm main body 21 so as to be relatively displaceable in the penetration direction of the hole, whereby the base end portion 21a of the arm main body 21 is inserted. As described above, it is supported so as to be capable of relative displacement. A spring retainer 27 protruding in a substantially horizontal direction is provided below a portion of the support member 26 inserted into the mounting hole 22. The upper surface of the spring retainer 27 and the lower surface of the base end portion 21 a of the arm body 21 are provided. A rocker arm spring 28 for biasing the arm main body 21 upward is attached between the two.

  The switching mechanism 30 includes a connecting pin 31 that is displaceable between a position that straddles B between the arm body 21 and the support member 26 and a position that does not straddle, and presses the connecting pin 31 hydraulically in one direction. And a spring 33 that presses the connecting pin 31 in the other direction opposite to the above-described one direction. Specifically, the switching mechanism 30 is in a disconnected state by driving the connecting pin 31 in one direction with the hydraulic pressure of the hydraulic mechanism 34, and by releasing the hydraulic pressure and driving in the other direction with the pressing force of the spring 33, Connected.

  The connecting pin 31 is attached to a bottomed hole-shaped pin hole 32 that is recessed in the support member 26 and extends in a substantially horizontal direction. The back part 32a on the back side of the pin hole 32 is relatively wide in the width direction, and the front part 32b on the front side (opening side) of the back part 32a is narrowed down relatively in the width direction. Yes. Further, the width of the base 31a on the base end side inserted into the pin hole 32 is substantially equal to the width of the back 32a, and the connecting pin 31 has a front end 31b on the side opposite to the base end. The width is substantially equal to the width of the front portion 32b.

  The spring 33 is a member that presses the connecting pin 31 in the direction of pushing out the pin pin 32 from the pin hole 32, and is interposed between the bottom surface of the pin hole 32 and the end surface of the base pin side of the connecting pin 31.

  The hydraulic mechanism 34 is a mechanism that pushes the connecting pin 31 into the pin hole 32 against the pressing force of the spring 33. The hydraulic mechanism 34 includes a hydraulic chamber 35 that drives the connecting pin 31 with hydraulic pressure, and an oil passage 36 that supplies hydraulic pressure to the hydraulic chamber 35. Specifically, the hydraulic chamber 35 is provided between the base portion 31 a of the connecting pin 31 and the front portion 32 b of the pin hole 32 in the inner portion 32 a of the pin hole 32. The oil passage 36 communicates with the hydraulic chamber 35 through the cylinder head 6, the lash adjuster 40, and the inside of the support member 26. The hydraulic mechanism 34 changes the hydraulic pressure supplied from the oil passage 36 to the hydraulic chamber 35 and changes the hydraulic pressure in the hydraulic chamber 35 to cooperate with the spring 33 to move the connecting pin 31 in one direction and the above. Drive in the other direction.

  The state of the variable valve mechanism 9 described above will be described below separately for (1) when the internal combustion engine is rotating at a low speed and (2) when the internal combustion engine is rotating at a high speed.

(1) During low-speed rotation of the internal combustion engine At this time, as shown in FIGS. 2A and 2C, the hydraulic pressure in the hydraulic chamber 35 increases, and the connecting pin 31 pushes the spring 33 with the hydraulic pressure. It is driven in a direction to be pushed into the pin hole 32 against this, and is completely accommodated in the pin hole 32. Therefore, the tip 31b of the connecting pin 31 does not straddle B between the arm main body 21 and the support member 26, and the arm main body 21 can be displaced relatively downward with respect to the support member 26, resulting in a disconnected state. . Therefore, at this time, as shown in FIGS. 3A and 3B, the rocker arm 20 causes the arm body 21 to repeat relative displacement with respect to the support member 26 in accordance with the rotation of the rotary cam 10. Oscillates around the tip 21b. However, at this time, in the present embodiment, the valve spring 8 is sufficiently stronger than the rocker arm spring 28, and the stroke in which the arm body 21 can be displaced relative to the support member 26 is secured sufficiently long. 7 is not driven at all. Therefore, the valve 7 is in a drive stop state. For this reason, in this disengaged state, half of the cylinders provided with the variable valve mechanism 9 are not inhaled, so that the internal combustion engine is operated by the output from only the remaining half of the cylinders. .

(2) During high-speed rotation of the internal combustion engine At this time, as shown in FIGS. 2 (b) and 2 (d), the connection pin 31 is pushed back by the pressing force of the spring 33 as the hydraulic pressure in the hydraulic chamber 35 decreases. Then, the tip portion 31 b of the connecting pin 31 protrudes outside the pin hole 32 across the space B between the arm main body 21 and the support member 26. The upper side surface of the protruding tip portion 31b abuts on the lower side surface of the base end portion 21a of the arm main body 21, so that the arm main body 21 cannot be relatively displaced downward with respect to the support member 26. It becomes a state. Therefore, at this time, as shown in FIGS. 3 (c) and 3 (d), the rocker arm 20 swings integrally with the arm body 21 and the support member 26 around the support member 26 according to the rotation of the rotary cam 10. Then, the valve 7 is pressed downward and driven by the output surface 23 of the arm body 21. Therefore, in this connected state, intake is also performed to the cylinder in which the variable valve mechanism 9 is provided, and the internal combustion engine is operated by the output from all the cylinders.

  According to the present embodiment, there is no need to provide two rocker arms as in Conventional Example 1, and there is no need to make the rocker arm a dual structure of an arm composed of an outer arm and an inner arm as in Conventional Example 2. Therefore, the structure of the rocker arm 20 is simplified.

  Further, since the switching mechanism 30 includes the hydraulic chamber 35 inside the support member 26, it is necessary to separately provide a pin driving mechanism for driving the connecting pin as in the conventional examples 1 and 2 outside the rocker arm 20. Therefore, the structure of the switching mechanism 30 is also simplified. Further, since the constituent elements of the switching mechanism 30 are collected inside the support member 26 that is the center of swinging, the weight on the tip side of the rocker arm 20 is reduced, which is advantageous for high-speed rotation.

  Further, since the oil passage 36 of the switching mechanism 30 is provided via the hydraulic lash adjuster 40, the oil passage 36 for the switching mechanism 30 and the oil passage for the lash adjuster 40 are common. As a result, the structure of the variable valve mechanism 9 is simplified.

  The present invention is not limited to the configuration of the above-described embodiment, and can be modified and embodied without departing from the spirit of the invention. For example, the following modifications 1 to 5 can be made. Also good.

[Modification 1]
Instead of providing the variable valve mechanism 9 only for half of a plurality of cylinders (not shown), one of the two valves 7 of all the cylinders having two intake valves 7 is provided. It may be provided only for each book. In this case, when the connection is released, intake is performed into each cylinder only from the other valve 7 different from the valve 7 provided with the variable valve mechanism 9, and both valves are connected when the connection is established. Intake from 7 into each cylinder.

[Modification 2]
As shown in FIGS. 4A and 4B, the rocker arm spring 28 is replaced with a rocker arm spring 51 which is stronger than the rocker arm spring 28 of the embodiment, or the support member 26 has a length in a substantially vertical direction. By changing to a shorter one, the stroke in which the arm body 21 can be relatively displaced with respect to the support member 26 in the disconnected state is shorter than the stroke in the embodiment, so that even in the disconnected state, The driving of the valve 7 may not be stopped completely, but the valve 7 may be driven with a lift amount smaller than that in the connected state.

[Modification 3]
As shown in FIG. 4 (c), the support member 26 is provided upside down in the longitudinal direction of the arm body 52 different from that of the embodiment, and the rear end portion of the arm body 52 is provided. The rotary cam 10 may be driven by being pressed from below.

[Modification 4]
Instead of the switching mechanism 30 in which the connection is released by increasing the oil pressure and in the connection state by decreasing the oil pressure, the switching mechanism 30 is in the connection state by increasing the oil pressure and is released by reducing the oil pressure. May be provided.

[Modification 5]
Instead of providing the output surface 23 at the distal end 21b of the arm body 21, an output pad 53 may be attached as shown in FIG.

It is a whole perspective view which shows the variable valve mechanism of the Example of this invention. In the embodiment, (a) and (c) are a side sectional view and a bottom sectional view showing the state when the arm main body and the support member are in the disconnected state, respectively, and (b) and (d) are in the connected state. It is side surface sectional drawing and lower surface sectional drawing which show the mode of time, respectively. In the embodiment, (a) and (b) are side views showing the state when the arm body and the support member are in a disconnected state, and (c) and (d) are side views showing the state when being connected. It is. (A) (b) (c) which shows the example of a change of the Example is a side view, (d) is side sectional drawing. (A) is a perspective view which shows the variable valve mechanism of the prior art example 1, (b) is a perspective view which shows the variable valve mechanism of the prior art example 2. FIG.

Explanation of symbols

7 Valve 9 Variable valve mechanism 10 Rotating cam 20 Rocker arm 21 Arm body 26 Support member 30 Switching mechanism 31 Connecting pin 35 Hydraulic chamber 36 Oil path B Between arm body and support member

Claims (2)

In a variable valve mechanism that changes an opening / closing amount of the valve by operating a rocker arm that is swingably interposed between the rotary cam and the valve.
The rocker arm includes an arm main body that contacts the rotary cam and the valve, and a support member that is provided at a rocking center of the rocker arm and supports the arm main body so as to be relatively displaceable linearly in the pressing direction of the rotary cam. And comprising
Switching is performed between a connection state in which the arm body and the support member are connected to each other so that the relative displacement is not possible, and a connection release state in which the connection is released to enable the relative displacement. A variable valve mechanism comprising a switching mechanism, wherein the opening / closing amount of the valve is changed by the switching. The switching mechanism includes a connection pin provided to be displaceable between a position straddling between the arm body and the support member and a position not straddling, and an inside of the support member that drives the connection pin hydraulically. The variable valve mechanism according to claim 1, further comprising: a hydraulic chamber provided in the hydraulic chamber; and an oil passage that supplies the hydraulic pressure to the hydraulic chamber.

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