JP2004340106A - Variable valve system in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously vary valve drive phase and valve lift quantity in simple constitution without causing reduction of valve overlap in a variable valve system in an internal combustion engine. <P>SOLUTION: This device is provided with a rocker arm mechanism 10, 110 comprising a first arm supported by a rocker shaft 21, 121 to be capable of oscillating, a second arm driven by a cam to oscillate around a support point on the side of the rocker shaft 21, 121, a third arm provided on a support shaft to be capable of oscillating to be displaced by oscillation of the second arm to drive the first arm, and a variable mechanism to displace the support point of the second arm on the side of the rocker shaft 21, 121. A camshaft 20, 120, the rocker shaft 21, 121, and the rocker arm mechanism 10, 110 are respectively provided on the intake valve side and the exhaust valve side to be symmetric as seen from a crankshaft direction of the internal combustion engine. These are composed in such a way that rotation direction of the camshaft 20, 120 is the same on the intake valve side and on the exhaust valve side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable valve train for an internal combustion engine that can change the drive phase and valve lift of intake and exhaust valves.
[0002]
[Prior art]
It is known that the phase or lift amount of a valve of an intake / exhaust system is changed in accordance with the operation state of an internal combustion engine in order to reduce exhaust gas or reduce fuel consumption of an internal combustion engine such as an automobile engine. As such a variable valve operating device, a vane type variable phase operating device that continuously changes a cam phase by hydraulic pressure is known.
[0003]
There is also known a cam-switching type valve train that switches a plurality of types of cams in accordance with the operating state of an internal combustion engine to adjust a valve driving phase and a lift amount to an operating state.
Alternatively, there has been known a mechanical type continuously variable valve operating device that uses a gear driven by a stepping motor, an intermediate lever, a return spring, and the like to change a driving phase and a lift amount of a valve (for example, a mechanical variable valve operating device). Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent No. 3245492
[0005]
[Problems to be solved by the invention]
However, the vane type variable phase valve operating apparatus can change the valve driving phase by changing the position of the vane, but cannot change the valve lift.
[0006]
On the other hand, a cam switching type valve operating device and a mechanical type continuously variable valve operating device can shift the lift amount and the phase, but the cam switching type valve operating device requires a plurality of types of cams, so parts are required. The number is large and the structure is complicated. Further, in the mechanical type continuously variable valve operating device, a mechanism for changing the lift amount and a mechanism for changing the phase are separately required, which complicates the structure and increases the size.
[0007]
In the case of a conventional general continuous phase variable valve operating device, if the closing timing of the intake valve is retarded, the valve opening start timing is also retarded. For this reason, there is a problem that valve overlap between intake and exhaust is reduced or eliminated, and fuel consumption is deteriorated due to pumping loss.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to be able to continuously change a valve driving phase and a valve lift amount with a simple configuration without reducing valve overlap. It is an object of the present invention to provide a variable valve operating device for an internal combustion engine.
[0009]
[Means for Solving the Problems]
For this reason, the variable valve apparatus for an internal combustion engine according to the present invention is driven by a camshaft rotatably provided in the internal combustion engine, a rocker shaft provided in the internal combustion engine, and a cam formed on the camshaft. A rocker arm mechanism that opens and closes an intake valve or an exhaust valve. The rocker arm mechanism is swingably supported on the rocker shaft, and is provided with a first arm capable of driving the intake valve or the exhaust valve, and the cam. A second arm that is driven and swings around the rocker shaft side, and a first arm that is swingably provided on a support shaft disposed near the rocker shaft and is displaced by the swing of the second arm. Arm, and a variable mechanism for displacing the fulcrum of the second arm on the rocker shaft side, the camshaft, the rocker shaft and the rocker arm machine. Are provided respectively on the intake valve side and the exhaust valve side so as to be symmetrical when viewed from the crankshaft direction of the internal combustion engine, and the rotational direction of the camshaft is provided between the intake valve side and the exhaust valve side. Are set identically.
[0010]
The second arm includes a base end rotatably connected by a connecting member provided on the rocker shaft side, a contact portion that contacts the cam, and an operating portion that contacts the third arm. And a spring for urging the third arm in a direction in which the second arm contacts the cam is provided between the support shaft and the third arm. preferable.
[0011]
Further, the third arm has a transmission surface portion that is in contact with the first arm, and the transmission surface portion has a conversion portion whose distance from the center of the support shaft changes in the rotation direction of the third arm. Is preferred.
In addition, the variable mechanism displaces the fulcrum by rotating the rocker shaft, and moves the corresponding contact portion of the second arm in the circumferential direction of the base circle of the cam, thereby changing the position of the second arm relative to the cam. It is preferable to change the rotation phase of the second arm.
[0012]
More preferably, the transmission surface portion has a non-conversion portion whose distance from the center of the support shaft does not change in the rotation direction of the third arm, and while the first arm is in contact with the non-conversion portion. The swing of the first arm is canceled even when the second arm is swingably driven.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a variable valve apparatus for an internal combustion engine according to an embodiment of the present invention will be described with reference to FIGS. 1 to 12. An internal combustion engine (engine) to which the present invention is applied includes an intake valve and an exhaust valve. The variable valve operating device capable of changing the valve lift amount and the opening / closing timing is provided on the intake valve side and the exhaust valve side, respectively. In the following, the variable valve device 10 provided mainly on the intake valve side will be described.
[0014]
As shown in FIG. 1, the variable valve train 10 includes a camshaft 20 that rotates by receiving a rotational driving force from a crankshaft (not shown), a rocker shaft 21 disposed in parallel with the camshaft 20, and a camshaft. A rocker arm mechanism 23 that opens and closes the valve (intake valve) 11 by rotating the cam 22 formed on the shaft 20 is provided.
[0015]
The camshaft 20 is configured to rotate in a direction indicated by an arrow R1 in FIG. The rocker shaft 21 is configured to be able to change the phase by a desired angle in the direction indicated by the arrow R2 in FIG. That is, the variable valve train 10 is provided with a variable mechanism 25 as shown in FIG. 2, and by operating this variable mechanism 25 based on a control signal from an ECU (not shown), the phase of the rocker shaft 21 is adjusted. Has been changed. In addition, such a phase change of the rocker shaft 21 may be performed using a motor or may be performed using hydraulic pressure.
[0016]
As shown in the figure, a connection member 27 having a spherical universal joint 26 such as a stud bolt is attached to the rocker shaft 21.
The rocker arm mechanism 23 includes a first arm 31, a second arm 32, and a third arm (transmission cam) 33 described below.
The first arm 31 is supported by the rocker shaft 21 so as to be relatively rotatable (swingable). An adjusting screw 35 is provided at the distal end portion 40 of the first arm 31. When the camshaft 20 rotates in the direction indicated by the arrow R1, the distal end of the adjusting screw 35 descends to open the valve 11. It is designed to be driven in the valve direction. The play between the first arm 31 and the valve 11 can be adjusted by the adjusting screw 35.
[0017]
As shown in FIG. 1, a force transmitting section 37 having a force transmitting member 36 such as a roller is provided near the adjusting screw 35.
Further, as shown in FIG. 2, the first arm 31 has shaft fitting portions 41 and 42 through which the rocker shaft 21 is inserted. It is formed in a bifurcated shape.
[0018]
Further, as shown in FIG. 1, the second arm 32 is provided between the rocker shaft 21 and the camshaft 20. The second arm 32 has a base end portion 50 pivotally attached to the above-mentioned universal joint portion 26 and an operating portion 51 which comes into contact with a relay portion 66 of the third arm 33 described later. ing.
Further, a contact portion 53 having a cam follower 52 such as a roller that comes into contact with the cam 22 is provided between the base end portion 50 and the operating portion 51. Accordingly, the second arm 32 swings with the rotation of the cam 22 about the center C1 of the universal joint 26 on the rocker shaft 21 side as a fulcrum.
[0019]
When the phase of the rocker shaft 21 is changed by the variable mechanism 25, the base end portion 50 of the second arm 32 is displaced in the circumferential direction of the rocker shaft 21, and accordingly, the contact portion 53 moves in the circumferential direction of the cam 22. , And the rotation phase of the second arm 32 with respect to the cam 22 changes to the retard side or the advance side.
At least a part of the second arm 32 is positioned between the shaft fitting portions 41 and 42 in a state where the contact portion 53 of the second arm 32 is in contact with the base circle 22 b of the cam 22. are doing.
[0020]
According to the configuration in which a part of the second arm 32 is sandwiched between the shaft fitting portions 41 and 42 in this manner, the contact portion between the second arm 32 and the cam 22 or the contact between the second arm 32 and the third arm 33 is formed. Even when an unbalanced load occurs in the contact portion or the like, the second arm 32 can be prevented from being displaced in the axial direction of the rocker shaft 21, and a problem such as uneven wear can be prevented.
[0021]
A support shaft 60 is arranged above the rocker shaft 21 in parallel with the rocker shaft 21, and a third arm (transmission cam) 33 is provided on the support shaft 60 so as to be swingable. The third arm 33 is urged by a return spring 61 in a counterclockwise direction in FIG. 1, that is, in a direction in which the contact portion 53 of the second arm 32 contacts the cam 22.
[0022]
The third arm 33 is provided with a transmission surface section 65 that contacts the force transmission section 37 of the first arm 31 and a relay section 66 that contacts the operating section 51 of the second arm 32. The transmission surface portion 65 functioning as a cam surface is displaced in the rotation direction of the third arm 33, that is, in the circumferential direction of the support shaft 60, as the second arm 32 swings.
Therefore, when the second arm 32 swings, the contact position between the force transmitting portion 37 and the transmitting surface portion 65 is displaced in the circumferential direction of the support shaft 60. That is, when the second arm 32 is swung toward the third arm 33 around the universal joint 26 by the protrusion 22 a of the cam 22, the transmission is performed when the third arm 33 is rotated clockwise via the relay 66. When the first arm 31 rotates in the direction of the arrow R3 by the surface portion 65, the valve 1 is opened.
[0023]
More specifically, the transmission surface portion 65 includes a non-conversion portion 70 having a constant distance from the center C2 of the support shaft 60 and a distance from the center C2 of the support shaft 60 increasing toward the distal end portion 33a of the third arm 33. And a conversion unit 71.
Among them, the non-converting portion 70 is formed in an R shape in which the distance from the center C2 of the support shaft 60 is constant as described above, so that while the force transmitting portion 37 is in contact with the non-converting portion 70, Also, even if the third arm 33 swings, the force transmitting section 37 does not displace, and the swing of the first arm 31 is canceled.
[0024]
More specifically, the non-conversion unit 70 determines that the swing start timing of the first arm 31 is substantially constant regardless of the phase adjustment amount of the rocker shaft 21 (that is, the advance amount or the retard amount of the second arm 32). The section is set so that That is, when the phase of the rocker shaft 21 is changed by the variable mechanism 25, the swing timing of the second arm 32 with respect to the cam 22 is advanced or retarded, but such phase adjustment of the second arm 32 is performed. Sometimes, the third arm 33 rotates to change the contact position of the non-converting portion 70 with the force transmitting portion 37, so that the phase adjustment margin of the second arm 32 is canceled and the swing start timing of the first arm 31 is started. Can be kept constant.
[0025]
Further, by forming the conversion unit 71 such that the distance from the center C2 of the support shaft 60 changes gradually with respect to the rotation direction of the third arm 33, the force transmission unit 37 and the conversion unit 71 are in contact with each other. During this period, the swing of the second arm 32 can be transmitted to the first arm 31 via the third arm 33.
Next, the operation of the variable valve train 10 will be described.
[0026]
FIG. 1 shows a state where the rocker shaft 21 is driven by the variable mechanism 25 to the retard side from the neutral position N by an angle θ1. In this case, the contact portion 53 of the second arm 32 is displaced with respect to the cam 22 by an angle α to the retard side (left side in FIG. 1) from the neutral point P1. Further, the operating portion 51 of the second arm 32 is displaced to the left in FIG.
[0027]
In this state, when the camshaft 20 rotates in the direction of the arrow R1 and the convex portion 22a of the cam 22 pushes up the contact portion 53 of the second arm 32 as shown in FIG. Pivoted counterclockwise about the center C1. Therefore, the operating section 51 of the second arm 32 pushes the relay section 66, and the third arm 33 rotates clockwise. As a result, the conversion unit 71 of the transmission surface unit 65 presses the force transmission unit 37, so that the first arm 31 rotates and the valve 11 opens.
[0028]
In this case, as shown in FIG. 1, since the force transmission unit 37 is located near the conversion unit 71 before the valve is opened, when the third arm 33 rotates clockwise, the transmission surface unit of the third arm 33 is rotated. Of the 65, the non-converting section 70 that is in contact with the force transmitting section 37 is shortened.
Therefore, while the cam angle is small, the first arm 31 starts to be driven in a direction to open the valve 11, and the first arm 31 is moved in the direction of arrow R3 while the force transmitting section 37 contacts the conversion section 71 over a long range. Pressed. Therefore, a large valve lift H1 (shown in FIG. 3) can be obtained.
[0029]
Therefore, in this case, as shown by the curve L1 in FIG. 4, the valve lift is large, and the peak of the valve lift is retarded. In this case, the valve driving is suitable for a large intake amount with a high rotation and a high load.
FIG. 5 shows a state where the rocker shaft 21 is driven to the neutral position N by the variable mechanism 25. In this case, the contact portion 53 of the second arm 32 coincides with the neutral point P1 with respect to the cam 22. In this case, the operating portion 51 of the second arm 32 is slightly displaced to the right in FIG. 5 as compared with the case shown in FIG. 1, and the third arm 33 is moved counterclockwise by this amount. Rotate slightly. Therefore, as compared with the state shown in FIG. 1, the contact point between the first arm 31 and the third arm 33 is shifted toward the non-converting section 70 of the transmission surface 65.
[0030]
In this state, when the camshaft 20 rotates and the convex portion 22a of the cam 22 pushes up the contact portion 53 of the second arm 32 as shown in FIG. 6, the second arm 32 moves the center C1 of the universal joint portion 26. It rotates counterclockwise as a fulcrum. For this reason, the operating part 51 of the second arm 32 pushes the relay part 66 and the third arm 33 rotates clockwise. As a result, the converting part 71 of the transmitting surface part 65 pushes the force transmitting part 37, The arm 31 rotates and the valve 11 opens.
[0031]
In other words, when the valve is closed as shown in FIG. 5, the distance from the force transmitting section 37 of the first arm 31 to the converting section 71 is slightly longer, and the force transmitting section 37 is connected to the non-converting section 70 as compared with the case shown in FIG. The contact distance increases. Therefore, when the third arm 33 rotates clockwise, the time during which the non-converting section 70 contacts the force transmitting section 37 and the first arm 31 is not driven increases. When the force transmission unit 37 starts to contact the conversion unit 71 thereafter, the first arm 31 is driven, and the intake valve 11 is opened.
[0032]
As described above, even when the rocker shaft 21 is driven to advance the second arm 32, the amount corresponding to the advance amount is canceled by the increase in the non-converting portion 70, and the opening is increased. The valve timing is the same as in the case shown in FIG.
On the other hand, the valve lift amount H2 (shown in FIG. 6) at this time becomes lower than that in the case shown in FIG. 1, and the valve closing timing of the valve is set to the second arm 32 as shown by the curve L2 in FIG. Is advanced in accordance with the advance amount of the motor, and the valve drive is suitable for medium rotation and medium load operation.
[0033]
FIG. 7 shows a state where the rocker shaft 21 is driven by the variable mechanism 25 from the neutral position N to the advance side by an angle θ2. In this case, the contact portion 53 of the second arm 32 is displaced with respect to the cam 22 by an angle β on the advance side (right side in FIG. 1) from the claim point P1. Further, the operating portion 51 of the second arm 32 is displaced rightward in FIG. 7, and the third arm 33 is displaced counterclockwise. Therefore, the non-converting portion 70 of the transmitting surface portion 65 of the third arm 33 that is in contact with the force transmitting portion 37 is longer than in the state of FIG. 5, and as a result, the converting portion 71 is further shorter.
[0034]
When the camshaft 20 rotates in this state, as shown in FIG. 8, the projection 22 a of the cam 22 causes the contact portion 53 of the second arm 32 to move at a timing earlier by the advance of the second arm 32. Pushing up, the second arm 32 rotates counterclockwise about the center C1 of the universal joint 26 as a fulcrum. Therefore, the operating section 51 of the second arm 32 pushes the relay section 66, and the third arm 33 rotates clockwise.
[0035]
In this case, since the period (distance) of the non-converting portion 70 in contact with the force transmitting portion 37 of the transmitting surface portion 65 of the third arm 33 is long, the first arm 3 starts swinging even when the third arm 33 is driven. As a result, the time required to advance the second arm 32 is canceled. Further, when the third arm 33 rotates clockwise with the swing of the second arm 32, the distance in which the force transmission unit 37 contacts the conversion unit 71 becomes short, and therefore, the amount of rotation of the first arm 31 is small. As a result, the valve lift amount H3 (shown in FIG. 8) decreases. Therefore, as shown by a curve L3 in FIG. 4, the valve is in a valve driving state suitable for low rotation and low load operation.
[0036]
Further, by setting the second arm 32 to be able to advance with respect to the cam 22 from the state shown in FIG. 7, the cylinder rest state (valve lift amount is minimal or zero) indicated by L4 in FIG. it can. Then, by stopping the operation of some of the cylinders according to the operation state of the engine, it is possible to improve the fuel efficiency.
By the way, in the above-described variable valve operating device 10, the rocker shaft 21 is connected to the variable mechanism 25 based on the phase from the start to the end of the curve L1 in FIG. In the case where the second arm 32 is driven, the period in which the second arm 32 is advanced with respect to the cam 22 is canceled by extending the period in which the third arm 33 is in contact with the non-converting section 70 and the force transmitting section 37. The valve opening start timing can be made substantially constant.
[0037]
Therefore, according to the variable valve apparatus 10, the valve closing timing can be changed while the valve opening timing of the intake valve is fixed. The amount of air is increased, and the effect of reducing fuel consumption is obtained.
Note that inertial intake means that pulsation of pressure generated by the intake action of the piston causes inertia in intake air in the intake pipe. By using this inertial intake and starting to close the intake valve 11 at the peak time of intake pulsation, fresh air can continue to flow into the cylinder even after the piston passes the bottom dead center, and the volume efficiency can be increased. . Since the peak timing of the pulsation varies depending on the engine speed, the intake air amount can be increased by starting to close the intake valve 11 in accordance with the peak timing.
[0038]
In addition, by optimally controlling the amount of air, a favorable combustion state is achieved, and unburned substances and the like are reduced, and the exhaust gas component is improved.
By the way, the configuration and operation of the variable valve operating device 10 provided on the intake side have been described so far. However, in the engine to which the present invention is applied, as shown in FIG. In addition, a variable valve operating device 110 including a camshaft 120, a rocker shaft 121, and a rocker arm mechanism 123 is provided.
[0039]
Here, the variable valve device 110 on the exhaust side is configured to be symmetrical with respect to the variable valve device 10 on the intake side when viewed from the crankshaft axial direction. It is configured similarly to the variable valve train 10 on the side. For this reason, the detailed configuration of the exhaust-side variable valve device 110 will not be described.
The variable valve device 110 is also provided with a variable mechanism (not shown) for changing the phase of the rocker shaft 121 in the same manner as the variable valve device 10 on the intake side. The shafts 21 and 121 are configured so that the phases can be independently adjusted.
[0040]
As shown, the camshafts 20, 120 are configured to rotate in the same direction on the intake side and the exhaust side. This is because, as shown in FIG. 10, the opening timing of the intake valve 11 is made constant and the closing timing of the exhaust valve is made constant. In other words, the variable valve operating devices 10 and 110 are This is because the valve overlap is always kept constant even when actuated.
[0041]
Here, as described above, since the exhaust-side variable valve device 110 and the intake-side variable valve device 10 are configured to be symmetrical left and right, the rotation of the camshafts 20 and 120 on the intake side and the exhaust side is controlled. If the directions are also symmetrical (that is, if the rotation directions of the camshafts 20 and 120 are opposite directions on the intake side and the exhaust side), the valve lift characteristics of the exhaust valve are the same as those on the intake side (see FIG. 4). . In other words, in this case, when the phase of the rocker shaft is changed, the valve opening timing of the exhaust valve is almost constant and the valve closing timing is different, so that the valve overlap cannot be kept constant.
[0042]
Therefore, in the present invention, the valve closing timing of the exhaust valve is substantially constant by configuring the variable valve operating device symmetrically on the intake side and the exhaust side and by setting the rotation directions of the camshafts 20 and 120 to be the same. Thus, the valve overlap with the intake valve 11 is kept substantially constant.
It should be noted that if the variable valve operating devices on the intake side and the exhaust side are arranged in the same manner without being symmetrical and the rotation direction of the camshaft is set in the opposite direction, it is possible to obtain valve lift characteristics as shown in FIG. Although possible, such a configuration is not practical. In other words, in general, in many engines, the valve train must be configured symmetrically on the intake side and the exhaust side due to restrictions on the mechanism of the valve train and layout restrictions. For example, it is desirable to install the variable valve operating device symmetrically on the intake side and the exhaust side. Therefore, in the present invention, since the variable valve gears are installed symmetrically on the intake side and the exhaust side, and the rotation directions of the camshafts 20 and 120 are set to the same direction on the intake side and the exhaust side. is there.
[0043]
By the way, in the case of a conventional general continuous phase variable valve operating device, if the valve closing timing is retarded, the valve opening timing is also retarded. For this reason, valve overlap of intake and exhaust is reduced or eliminated, and pumping loss occurs.
On the other hand, according to the variable valve operating devices 10 and 110, the valve closing timing can be advanced or retarded with the valve opening timing of the intake valve 11 fixed, and the valve closing timing of the exhaust valve can be adjusted. Since the valve opening timing can be advanced or retarded in a state where is fixed, the effect of increasing the intake air amount can be obtained by retarding the closing timing of the intake valve while maintaining the valve overlap. Therefore, an effect of reducing fuel consumption can be obtained.
[0044]
Further, by providing such variable valve operating devices 10 and 110, it is not necessary to provide an intake or exhaust throttle for controlling the amount of intake air, so that the cost can be reduced.
Since the variable valve device of the internal combustion engine as one embodiment of the present invention is configured as described above, for example, the operations of the variable valve devices on the intake side and the exhaust side are controlled as follows.
(1) At full load or acceleration
In this case, as shown in FIG. 11, both the intake valve 11 and the exhaust valve are controlled so that the valve lift is maximized (corresponding to the lift amount L1). As a result, at full load or during acceleration, the valve lift characteristic has priority on intake and exhaust efficiency, and the valve lift characteristic has priority on engine performance.
(2) At startup
To improve the startability, it is effective to increase the temperature during compression in the cylinder during cranking. Therefore, at the time of starting, for example, as shown in FIG. 12, the exhaust valve is controlled to have a high lift L1, and the intake valve 11 is controlled to have a medium lift L2 to a low lift L3. This is because, when the engine is running at a low speed, the intake valve flow rate increases when the intake valve closing timing is advanced earlier than when the engine is running at a high speed, even if the valve lift amount is slightly reduced. This is because the temperature rises.
[0045]
By setting the exhaust valve to the high lift L1 and setting the intake valve 11 to the medium lift L2 to the low lift L3 when starting the engine, the startability is improved.
(3) When the post-processing device is activated (Part 1)
When using a post-processing device (for example, an oxidation catalyst) that improves the purification performance as the exhaust gas temperature becomes higher, when the post-processing device is activated, the exhaust valve is set to the high lift L1 as in the case of the start. At the same time, the intake valve 11 is controlled so as to be in the middle lift L2 to the low lift L3. In this case, since the intake air flow rate is reduced as described above, the air-fuel ratio becomes rich by that amount, and the exhaust gas temperature can be raised.
(4) When the post-processing device is activated (Part 2)
When activating the exhaust gas post-processing device, the cylinder closing operation is performed by controlling both valve lifts of some of the cylinders (usually half of the cylinders described above) to zero. At this time, when an output equivalent to that in the non-cylinder operation is required, the working cylinder in the cylinder-stop operation has a larger work amount per cylinder than in the non-cylinder operation. That is, since the fuel consumption per cylinder is large, the exhaust gas temperature rises significantly compared to the non-cylinder operation.
5) Constant speed driving when empty
Also, when the vehicle is in an empty state and running at a substantially constant speed, control is performed such that both valve lifts become zero for some of the cylinders, as described above. As a result, some of the cylinders are brought into a closed cylinder state. As a result, the working cylinder is operated at a higher load than the non-working cylinder, so that the fuel efficiency is improved and the fuel consumption can be reduced.
(6) NOx reduction
During normal operation, the exhaust valve is controlled to have a medium to low lift, and the intake valve 11 is controlled to have a high lift. By adopting such a valve lift characteristic, there is an advantage that the internal EGR can be increased by not leaving all the combustion gas in the cylinder but leaving a part thereof, and the NOx can be reduced.
[0046]
Note that 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, the variable valve systems on the intake side and the exhaust side may be configured as shown in FIG. Here, the variable valve operating device 10A is configured such that the forked portions 32a and 32b are formed on the base end portion 50 side of the second arm 32, and at least a part of the first arm 31 includes the forked portions 32a and 32b. It is configured to be located between them. Also. Other configurations, operations, and effects are the same as those of the variable valve apparatus 10 of the above embodiment, and thus common members are denoted by the same reference numerals and description thereof is omitted.
[0047]
As described above, even when the first arm 31 is partially sandwiched between the forked portions 32a and 32b, the contact portion between the second arm 32 and the cam 22, or the second arm 32 and the third When an unbalanced load is generated at a contact portion between the arm 33 and the like, the second arm 32 can be prevented from being displaced in the axial direction of the rocker shaft 21, so that problems such as uneven wear can be prevented.
[0048]
In addition, a configuration shown in FIG. 14 may be used. This variable valve train 10B differs from the variable valve train 10 of the above embodiment in that the shaft fitting portion 31a of the first arm 31 is not bifurcated. The other configuration is the same as that of the variable valve device 10 of the first embodiment, and thus the same reference numerals are given to the common members, and description thereof will be omitted.
[0049]
【The invention's effect】
As described in detail above, according to the variable valve operating apparatus for an internal combustion engine of the present invention, the valve driving phase and the valve lift can be continuously changed with a relatively simple configuration without causing a decrease in valve overlap. There is an advantage that it can be performed (claim 1).
[0050]
By providing a spring for urging the third arm, the positions of the second arm and the third arm can be held so that the second arm always contacts the cam (claim 2).
In addition, by providing a conversion portion that changes the distance from the center of the support shaft to the transmission surface portion of the third arm, the swing amount of the second arm is converted by the third arm and transmitted to the first arm. Therefore, by moving the position of the fulcrum on the rocker shaft side of the second arm by the variable mechanism, the lift amount of the intake or exhaust valve can be changed.
[0051]
Further, the drive phase of the intake or exhaust valve can be continuously changed by a variable mechanism for displacing the fulcrum about the axis of the rocker shaft (claim 4).
While the first arm is in contact with the non-converting portion, the swing of the first arm is canceled even if the second arm is driven to swing, so that the valve opening timing or The valve closing timing can be made substantially the same (claim 5).
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a variable valve operating device for an internal combustion engine according to an embodiment of the present invention, and is a diagram showing a state in which a phase is retarded.
FIG. 2 is a schematic view showing a variable valve operating device for an internal combustion engine according to one embodiment of the present invention, and is a top view of FIG.
FIG. 3 is a schematic diagram showing a variable valve operating device for an internal combustion engine according to one embodiment of the present invention, and is a diagram showing a state in which a valve is opened in a state where a phase is retarded.
FIG. 4 is a diagram showing a relationship between a cam angle and a valve lift of the variable valve operating device for an internal combustion engine according to one embodiment of the present invention.
FIG. 5 is a schematic diagram showing a variable valve operating device for an internal combustion engine according to an embodiment of the present invention, showing a state in which the phase is neutral.
FIG. 6 is a schematic diagram showing a variable valve operating device for an internal combustion engine according to an embodiment of the present invention, and is a diagram showing a valve opening state in a phase neutral state.
FIG. 7 is a schematic diagram showing a variable valve operating device for an internal combustion engine according to an embodiment of the present invention, showing a state where a phase is advanced.
FIG. 8 is a schematic diagram showing a variable valve operating device for an internal combustion engine according to an embodiment of the present invention, showing a state in which a valve is opened in a state where a phase is advanced.
FIG. 9 is a schematic diagram showing an overall configuration of a variable valve apparatus for an internal combustion engine according to an embodiment of the present invention.
FIG. 10 is a diagram for explaining the operation of the variable valve apparatus for an internal combustion engine according to one embodiment of the present invention, and is a valve lift diagram of an intake valve and an exhaust valve.
FIG. 11 is a view for explaining the operation of the variable valve apparatus for an internal combustion engine according to one embodiment of the present invention, and is a valve lift diagram of an intake valve and an exhaust valve at full load and at acceleration.
FIG. 12 is a view for explaining the operation of the variable valve apparatus for an internal combustion engine according to one embodiment of the present invention, and is a valve lift diagram of an intake valve and an exhaust valve at the time of starting.
FIG. 13 is a schematic diagram showing a modified example of the variable valve apparatus for an internal combustion engine according to one embodiment of the present invention.
FIG. 14 is a schematic view showing a modified example of the variable valve apparatus for an internal combustion engine according to one embodiment of the present invention.
[Explanation of symbols]
10, 10A, 10B, 110 Variable valve gear
11 Intake valve
20,120 camshaft
21, 121 Rocker shaft
22, cam
23,123 rocker arm mechanism
25 Variable mechanism
26 Universal joint
27 Connecting members
31 1st arm
32 2nd arm
33 3rd arm
37 Force transmission unit
60 support shaft
61 Spring
65 Transmission surface
70 Non-conversion part
71 Conversion unit

Claims (5)

A camshaft rotatably provided in the internal combustion engine,
A rocker shaft provided in the internal combustion engine,
A rocker arm mechanism driven by a cam formed on the camshaft to open and close an intake valve or an exhaust valve,
The rocker arm mechanism,
A first arm swingably supported by the rocker shaft and capable of driving the intake valve or the exhaust valve;
A second arm driven by the cam and swinging around the rocker shaft side as a fulcrum;
A third arm that is swingably provided on a support shaft disposed near the rocker shaft and is displaced by the swing of the second arm to drive the first arm;
A variable mechanism for displacing the fulcrum on the rocker shaft side of the second arm;
The camshaft, the rocker shaft, and the rocker arm mechanism are provided on the intake valve side and the exhaust valve side, respectively, so as to be symmetrical when viewed from the crankshaft direction of the internal combustion engine. A variable valve train for an internal combustion engine, wherein the rotation direction of the camshaft is set to be the same on the exhaust valve side. The second arm includes a base end rotatably connected by a connection member provided on the rocker shaft side, a contact portion abutting on the cam, and an operating portion abutting on the third arm. As well as
2. A spring provided between said support shaft and said third arm for biasing said third arm in a direction in which said second arm comes into contact with said cam. Variable valve train for internal combustion engines. The third arm has a transmission surface in contact with the first arm,
3. The variable valve train for an internal combustion engine according to claim 1, wherein the transmission surface portion includes a conversion portion whose distance from the center of the support shaft changes in a rotation direction of the third arm. . The variable mechanism displaces the fulcrum by rotating the rocker shaft, and moves the corresponding contact portion of the second arm in the circumferential direction of the base circle of the cam, so that the second 4. The variable valve train for an internal combustion engine according to claim 2, wherein a rotation phase of the arm is changed. The transmission surface has a non-converting portion whose distance from the center of the support shaft does not change in the rotation direction of the third arm, and while the first arm is in contact with the non-converting portion, the second converting portion has a second converting portion. 5. The variable valve apparatus for an internal combustion engine according to claim 3, wherein the swing of the first arm is canceled even if the arm is driven to swing.

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