JP2005030390A - Valve operating device for internal combustion engine - Google Patents

Abstract

There is provided a valve operating apparatus for an internal combustion engine capable of suppressing engine fluctuations by eliminating a difference in valve lift between cylinders caused by a difference in structure or rigidity of a valve operating mechanism of a plurality of cylinders.
In a valve operating apparatus for an internal combustion engine having a plurality of cylinders having different structure or rigidity of a valve mechanism, a difference in valve lift caused between the plurality of cylinders due to a difference in structure or rigidity of the valve mechanism. It is characterized by having correction means for correcting the valve lift amount so as to make the valve lift amounts of the plurality of cylinders substantially uniform.
[Selection] Figure 2

Description

  The present invention relates to a valve operating apparatus for an internal combustion engine, and more particularly to a valve operating apparatus for an internal combustion engine in which the valve operating characteristics of each cylinder in a multi-cylinder engine having a plurality of cylinders are different from each other.

In a multi-cylinder engine having a plurality of cylinders, there is a technology for improving the fuel efficiency by making the valve operation characteristics of each cylinder different from each other, for example, stopping the operation of intake and exhaust valves of some cylinders in a specific operating range. It has already been proposed (see Patent Document 1).
JP 2002-155712 A

  However, in order to make the operating characteristics of the valve operating mechanisms provided in a plurality of cylinders different from each other, if the structures of the valve operating mechanisms for each cylinder are made different from each other, each cylinder formed on a common camshaft has It is conceivable that there is a difference between cylinders in the amount of transmission of the corresponding cam head to the valve.

  This is because, for example, a connection switching means is provided on a rocker arm provided between the cam and valve of some cylinders, and the connection switching means is operated according to the operating state of the engine to connect the cam and the valve. If the state can be interrupted, the interlocking error between the cam and the valve must be larger than that without the switching means for the sake of ensuring smooth operation of the switching means.

  Also, for example, if the rigidity of the rocker arm must be different for each cylinder due to layout reasons, etc., the rocker arm with low rigidity has a larger amount of bending deformation, which is also linked between the cam and the valve. Inter-cylinder error is a factor in the state.

  That is, if there is a difference between the cylinders in the structure or rigidity of the lift amount transmission portion provided between the cam and the valve, there is a possibility that a difference will occur in the actual valve lift amount for each cylinder. This can be a factor that causes rotational fluctuations particularly in the low-speed operation region of the engine.

  The present invention has been devised to solve such problems of the prior art, and its main object is to provide a cylinder with a valve lift amount caused by a difference in structure or rigidity of a valve mechanism of a plurality of cylinders. It is an object of the present invention to provide a valve operating apparatus for an internal combustion engine that eliminates the difference between them and can suppress fluctuations in engine rotation.

  In order to solve such a problem, according to claim 1 of the present invention, in a valve operating apparatus for an internal combustion engine having a plurality of cylinders having different valve operating mechanism structures, a plurality of valve operating mechanisms are structured to differ. It is characterized by having a correction means for correcting the difference in valve lift amount generated between the cylinders to make the valve lift amounts of the plurality of cylinders substantially uniform.

  According to a second aspect of the present invention, in a valve operating apparatus for an internal combustion engine having a plurality of cylinders having different valve mechanism rigidity, a difference in valve lift caused between the plurality of cylinders due to a difference in rigidity of the valve mechanism is corrected. And correcting means for making the valve lift amounts of the plurality of cylinders substantially uniform.

  Further, in claim 3, the correction means in claim 1 or claim 2 is a difference in cam profile attached corresponding to a difference in structure or rigidity of the valve drive member.

  In this way, the amount of transmission of the cam lift to the valve differs between cylinders due to the clearance or rigidity difference between the transmission members of the valve operating mechanism, that is, the valve operating characteristic variable mechanism provided between the cam and the valve. Even if this occurs, it is possible to make the valve lift amounts of all the cylinders uniform by correcting the difference, so that a great effect can be obtained for further improving the smoothness in the low speed operation region. In particular, if the cam profile is set in consideration of the difference in the structure or rigidity of the lift amount transmission part provided between the cam and the valve between the cylinders, the amount of transmission of the cam lift to the valve between the cylinders The error can be easily corrected.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a vehicle equipped with a V-type engine equipped with a valve mechanism to which the present invention is applied. In this vehicle, the engine E is arranged in front of the front axle with the cylinder row facing the vehicle body.

  As shown in FIG. 2, the V-type engine E includes two cylinder banks 1F and 1R arranged in a V shape in the front-rear direction, and cylinder bores 3 formed in the cylinder block portions 2 of both cylinder banks 1F and 1R. A piston 4 slidably engaged with each cylinder bore 3 and a single crankshaft 6 connected to each piston 4 via a connecting rod 5 are provided.

  The cylinder heads 7 of the two cylinder banks 1F and 1R are connected to the combustion chamber 8, the intake port 10 where the communication with the combustion chamber 8 is intermittently connected by the intake valve 9, and the communication with the combustion chamber 8 via the exhaust valve 11. An intermittent exhaust port 12 is provided. In each intake valve 9 and each exhaust valve 11, the lifts of cams 14F and 14R arranged on a single camshaft 13F and 13R extending in the cylinder row direction at the intermediate portion between the intake valves 9 and the exhaust valves 11 are intake rocker arms 15F. -15R and the exhaust rocker arms 16F and 16R are transmitted, and the intake and exhaust valves 9 and 11 are driven to open and close in synchronization with the rotation of the crankshaft 6, in other words, the vertical movement of the piston 4.

  The valve mechanism of the front bank 1F located on the vehicle front side of the two cylinder banks 1F and 1R has the combustion cycle suspended by stopping the operation of both the intake and exhaust valves 9 and 11 in a specific operating state. The valve operating state switching mechanisms 21e and 21s for causing the two rocker arms 15F and 16F are incorporated. Hereinafter, the switching mechanisms 21e and 21s will be schematically described with reference to FIG.

  FIG. 3 shows one cylinder of a valve mechanism having switching mechanisms 21e and 21s. The front bank 1F is provided with this mechanism for all cylinders. In FIG. 3, an intake rocker shaft 22 that supports an intake rocker arm 15F that drives the intake valve 9 to open and close, and an exhaust rocker shaft 23 that supports an exhaust rocker arm 16F that opens and closes the exhaust valve 11 form one camshaft 13F. Inverted triangular positions as apexes extend in parallel to each other in the cylinder row direction. Two intake valves 9 and two exhaust valves 11 are provided for each cylinder.

  As shown in FIG. 4, the camshaft 13F has one intake cam 14s that drives two intake valves 9 simultaneously per cylinder and two exhaust cams 14e that individually drive two exhaust valves 11. They are formed adjacent to each other in such a manner that one intake cam 14s is sandwiched between two exhaust cams 14e.

  The rocker arms 15F and 16F that transmit the heads of the cams 14e and 14s to the valves 9 and 11 are driven rocker arms 15d and 16d that make the rollers 24 provided at the respective ends roll in contact with the corresponding cams 14e and 14s. And a driven base rocker arm 15i, 16i in which a cam slipper 26 at one end thereof is slidably contacted with a common base circle 25 formed on the camshaft 13, and a tappet screw 27 at the other end is directly brought into contact with the valve stem end. On the intake valve 9 side, there are two rocker arms including one drive rocker arm 15d corresponding to one intake cam 14s and two driven rocker arms 15i individually corresponding to the two intake valves 9. Intake rocker shaft with one drive rocker arm 15d sandwiched between driven rocker arms 15i It is pivotally supported on the 2. On the exhaust valve 11 side, two drive rocker arms 16d individually corresponding to the two exhaust cams 14e and two driven rocker arms 16i individually corresponding to the two exhaust valves 11 are symmetrically positioned on the exhaust rocker shaft 23. It is pivotally supported by. Note that the intake rocker arm 15F and the exhaust rocker arm 16F have a common base circle 25 in sliding contact with a cam slipper 26 at one end thereof.

  One of the driven rocker arms 15i of the intake valve 11 (upper side in FIG. 3) has a bottomed first guide hole 31 that opens toward the drive rocker arm 15d at the center, and is formed in parallel with the axis of the intake rocker shaft 22. The first connecting pin 32 is slid into it. The first connecting pin 32 is always elastically biased toward the drive rocker arm 15d by the compression coil spring 33. The drive rocker arm 15d is formed with a second guide hole 34 concentrically with the first guide hole 31 at a stationary position where the roller 24 contacts the base circle portion B of the intake cam 14s. The second connecting pin 35 in a state where one end thereof is in contact with the first connecting pin 32 is slidably engaged. The other (lower side in FIG. 2) driven rocker arm 15i is formed with a substantially bottomed third guide hole 36 similar to the one driven rocker arm 15i, and the second connecting pin 35 has a second guide pin 35 therein. A stopper pin 37 in a state in which one end is in contact with the other end is slidably engaged.

  In the intake rocker shaft 22, two oil supply passages 41a and 41b are formed for pumping the lubricating oil pumped up from the oil pan. These two oil supply passages 41a and 41b are connected to each other through communication holes 42a and 42b formed in the pivotal support portions of the corresponding driven rocker arms 15i and passage holes 43a and 43b provided in the respective driven rocker arms 15i. The first guide hole 31 and the bottom of the third guide hole 36 communicate with each other.

  The exhaust valve 11 side has a bottomed first position between the paired drive rocker arm 16d and driven rocker arm 16i at positions where the rollers 24 are aligned with each other at a stationary position where the roller 24 contacts the base circle portion B of the exhaust cam 14e. The 1 guide hole 51 and the 2nd guide hole 52 are formed in parallel with the axis line of the exhaust rocker shaft 22, and the connection pin 53 and the stopper pin 54 are slid in each in it. The connecting pin 53 on each driven rocker arm 16 i side is always elastically biased toward the drive rocker arm 16 d side by the compression coil spring 55.

  Also in the exhaust rocker shaft 23, as with the intake rocker shaft 22, two oil supply passages 44 a and 44 b for pumping the lubricating oil pumped up from the oil pan are formed, and these oil supply passages 44 a and 44 b are Communication holes 45a and 45b formed in the pivotal support portions of the driven and driving rocker arms 16d and 16i, respectively, and passage holes 46a and 46b provided in the driven and driving rocker arms 16d and 16i, respectively. And communicate with the bottoms of the corresponding guide holes 51 and 52.

  The switching mechanisms 21e and 21s selectively switch the hydraulic pressure from the oil supply passages 41a, 41b, 44a, and 44b by controlling the opening and closing of solenoid valves (not shown) according to the operating state of the engine. Operate. That is, when hydraulic pressure is applied to the first guide hole 31 of one driven intake rocker arm 15i and the first guide holes 51 on the side of both driven exhaust rocker arms 16i, the mutually connected pins are connected to the compression coil springs 33 and 35. The elastic force is also moved to help each pin move to a position straddling the drive rocker arm and the driven rocker arm, and the drive and driven rocker arms are integrally coupled (the state shown in FIG. 3). On the other hand, when hydraulic pressure is applied to the third guide hole 35 of the other driven intake rocker arm 15i and the second guide holes 52 on both drive exhaust rocker arms 16d, the mutually connected pins are connected to the compression coil spring 33. The pin 35 moves while being compressed and moved to a position where each pin slides only into the corresponding guide hole, and the drive and driven rocker arms are separated from each other.

  Thus, during idling operation, if the intake and exhaust valves 9 and 11 are driven and the driven rocker arms are separated from each other, the rocker arms can be displaced relative to each other by the intake and exhaust cams 14e and 14s. The driven rocker arms 15d and 16d to be driven have no influence on the driven rocker arms 15i and 16i, and the intake and exhaust valves 9 and 11 remain closed.

  When the engine is in a normal mode at a predetermined rotational speed or higher, if the hydraulic pressure is applied to the first connection pin 32 on the intake side and the second connection pin 54 on the exhaust side, each pin straddles between adjacent rocker arms. It becomes a state. Accordingly, the drive and driven rocker arms 15d, 15i, 16d, and 16i are connected to each other so as to be able to swing integrally, and the two intake and exhaust valves 9 and 11 are respectively provided by the profiles of the intake and exhaust cams 14e and 14s. Are driven to open.

  As described above, in this V-type engine, the structures of the valve operating mechanisms provided in the two banks 1F and 1R are different from each other, and the valve operating mechanism on the front bank 1F side includes the built-in switching mechanism 21e. In order for the 21 s pin to move smoothly in the guide hole, a predetermined clearance is required between the guide hole and the pin. If there is a difference in the structure of the valve mechanism between the plurality of cylinders, the lift amount of the cam 14F of the front bank 1F is transmitted to the valves 9 and 11 as compared with the rear bank 1R where the switching mechanisms 21e and 21s are not provided. The amount is reduced by this clearance. As a result, when the same camshaft is used for both the banks 1F and 1R, the valve lift amount (solid line) of the front bank, as shown in FIG. 5, particularly in the overlap region of the intake valve 9 and the exhaust valve 11, There is a difference between the rear bank valve lift amount (dotted line). This is a factor that causes rotational fluctuations in the low speed range.

  In the present embodiment, in order to correct the valve lift amount generated between the plurality of cylinders due to the difference in the structure of the valve operating mechanism to make the valve lift amounts of the plurality of cylinders substantially uniform, The profile of the nose portion of the cam 14F formed on the camshaft 12F of the front bank 1F is made larger than the profile of the nose portion of the cam 14R formed on the camshaft 12R of the rear bank 1R.

  Each cam is processed by a numerically controlled automatic grinding machine. The input parameters of the camshafts provided in both banks are appropriately set in advance according to the difference in valve lift between the two banks, as shown in FIG. As described above, it is possible to suppress the difference between the valve lift amounts of both banks 1F and 1R.

  By providing the above-described switching mechanism, for example, if the rocker shaft is provided with an oil passage and the support rigidity of one rocker arm is lower than the other, as shown in FIG. A difference occurs between 1R. Such a difference in rigidity also causes a difference in valve timing between the banks 1F and 1R. Therefore, the difference in valve lift generated between the plurality of cylinders due to the difference in rigidity of the valve operating mechanism is corrected so that the plurality of cylinders are corrected. It is preferable that the cam profiles of the camshafts provided in both banks are differentiated so that the valve lift amount can be made substantially uniform.

  In this way, by making the actual valve lift amount between the banks 1F and 1R substantially uniform, fluctuations in the in-cylinder pressure between different banks can be suppressed. The term “substantially uniform” as used herein means that the variation in the in-cylinder pressure between the cylinders provided with the valve mechanisms different in structure or rigidity can be suppressed. It is preferable that the cylinders be the same.

  As shown in the above embodiment, if the present invention is applied to a horizontal V-type engine, the valve operating state switching mechanisms 21e and 21s are provided on the side of the front bank 1F having a sufficient space in the engine room. Since the accessibility to the switching mechanisms 21e and 21s is improved, the maintainability is improved.

  FIG. 8 shows a second embodiment of the present invention. This engine E ′ is provided with a switching mechanism 21e, 21s having basically the same structure as that shown in FIGS. 3 and 4 in the rear bank 1R, as compared with the front bank 1F without the switching mechanism 21e, 21s. The transmission amount of the lift amount of the cam 14R of the rear bank 1R to the valves 9 and 11 is reduced by this clearance. As a result, when the same camshaft is used for both banks 1F and 1R, the valve lift amount of the front bank 1F (solid line) and the valve lift amount of the rear bank 1R (in the overlap region between the intake valve 9 and the exhaust valve 11) ( The difference shown in FIG.

  Therefore, in this embodiment, the profile of the nose portion of the cam 14R formed on the camshaft 12R of the rear bank 1R is made larger than the profile of the nose portion of the cam 14F formed on the camshaft 12F of the front bank 1F. did. Thereby, as shown in FIG. 10, it is suppressed that a difference arises in the valve lift amount of both banks 1F and 1R.

  Further, as shown in FIG. 11, even when a difference occurs between the two banks 1F and 1R in the load / displacement relationship of the rocker arm, a difference is caused in the valve timing between the both banks 1F and 1R. By making a difference in the cam profiles of the camshafts provided in both banks according to the difference in rigidity, the valve lift amounts of a plurality of cylinders can be made substantially uniform as in the first embodiment.

  As shown in the above-described embodiment, if the valve operating state switching mechanisms 21e and 21s are provided in the rear bank 1R in the horizontal V-type engine, the front bank 1F that increases the heat load because it is always driven is advanced. Since it can be arranged on the front side in the direction, the cooling performance by the traveling wind can be improved, and the rear bank 1R close to the driver's seat becomes a pause bank, so that the influence of noise in the vehicle compartment can be reduced.

It is a top view of the vehicle carrying the V type engine to which this invention was applied. 1 is a schematic configuration diagram showing a first embodiment of a V-type engine to which the present invention is applied. It is sectional drawing which follows the II-II line | wire in FIG. FIG. 4 is a side view of the vicinity of line III-III in FIG. 3. FIG. 3 is a valve timing diagram of the engine of FIG. 2 to which the present invention is not applied. FIG. 3 is a valve timing diagram of the engine of FIG. 2 to which the present invention is applied. FIG. 3 is a load / displacement diagram of the rocker arm of the engine of FIG. 2 that is the subject of the present invention. It is a schematic block diagram which shows 2nd Example of the V-type engine to which this invention was applied. FIG. 9 is a valve timing diagram of the engine of FIG. 8 to which the present invention is not applied. FIG. 9 is a valve timing diagram of the engine of FIG. 8 according to the present invention. FIG. 9 is a load / displacement diagram of the rocker arm of the engine of FIG. 8 that is the subject of the present invention.

Explanation of symbols

1F and 1R Cylinder bank 9 Intake valve 11 Exhaust valve 13 Camshaft 14 Cam 15 Intake rocker arm 16 Exhaust rocker arm 21 Valve operation state switching mechanism

Claims (3)

In a valve operating apparatus for an internal combustion engine provided with a plurality of cylinders having different valve operating mechanisms,
An internal combustion engine comprising correction means for correcting a difference in valve lift amount generated between a plurality of cylinders due to a difference in structure of the valve operating mechanism to substantially uniform the valve lift amounts of the plurality of cylinders. Engine valve gear. In a valve operating apparatus for an internal combustion engine including a plurality of cylinders having different valve mechanism rigidity,
An internal combustion engine comprising correction means for correcting a difference in valve lift generated between a plurality of cylinders due to a difference in rigidity of the valve operating mechanism to make the valve lifts of the plurality of cylinders substantially uniform. Valve gear. 3. The valve operating apparatus for an internal combustion engine according to claim 1, wherein the correction means is a difference in cam profile corresponding to a difference in structure or rigidity of the valve operating mechanism.

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