JP2815198B2 - Variable valve timing mechanism for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention appropriately adjusts the opening timing of an intake / exhaust valve in accordance with the operating state of a four-stroke engine. The present invention relates to a variable valve timing mechanism of an engine that can appropriately adjust both the valve timing and the valve timing.

[Conventional technology]

In a four-stroke engine, the valve overlap period (the period during which the intake and exhaust valves are simultaneously opened) is prolonged by accelerating the opening timing of the valve and delaying the closing timing of the valve in the high-speed range, thereby increasing the inertia of the intake and exhaust. The effect is used to increase the output of the engine by increasing the intake and exhaust efficiencies, and in the low-speed range, the valve overlap period is shortened by delaying the valve opening timing and shortening the valve closing timing. Conventionally, various variable vibrating timing mechanisms have been provided in order to prevent exhaust gas recirculation and intake air blow-through and to prevent a decrease in engine output.

The present applicant has previously filed an application for a variable valve timing mechanism that can appropriately adjust the opening timing of the intake and exhaust valves using an eccentric shaft. (JP-A-63-1707).

The above-mentioned application includes a camshaft angular velocity variable mechanism for changing an angular velocity at a rotation position of a camshaft on a side portion of a cylinder, and a control mechanism for controlling the camshaft angular velocity variable mechanism. The variable mechanism is disposed outside the in-line multi-cylinder internal combustion engine.

[Problems to be solved by the invention]

In the variable valve timing mechanism, since the camshaft angular velocity variable mechanism is disposed outside the internal combustion engine,
The internal combustion engine itself protrudes in the axial direction of the camshaft, making it difficult to achieve compactness. In particular, in a motorcycle, since a space for mounting the equipment is limited, a problem that it is difficult to reduce the size of the motorcycle becomes a serious problem.

The present invention has been made in view of the above circumstances, and can prevent the internal combustion engine from protruding in the axial direction of the camshaft and becoming wider, and furthermore, the camshaft angular velocity variable mechanism is less likely to interfere with the camshaft drive system, and further compared. It is an object of the present invention to provide a variable valve timing mechanism of an internal combustion engine that can operate a camshaft angular velocity variable mechanism with a relatively small driving force.

[Means for solving the problem]

In order to achieve the above object, in the first invention of the present application, in an in-line multi-cylinder internal combustion engine in which a plurality of cylinders are formed in series on a common cylinder block, an angular velocity at a rotation position of a cow shaft between the plurality of cylinders A variable camshaft angular velocity mechanism is arranged, a control mechanism for controlling the camshaft angle variable mechanism is disposed on the opposite side of the camshaft angular velocity variable mechanism across the one cylinder,
A cam drive shaft for rotating the cam shaft is provided in parallel with the cam shaft separately from the cam shaft, and the cam drive shaft is connected to the cam shaft angular velocity variable mechanism and also to the crank shaft. It is characterized by:

According to a second aspect of the present invention, in addition to the first aspect, in the in-line two-cylinder internal combustion engine, one end of the cam drive shaft is connected to the variable camshaft angular velocity mechanism, and the other end of the cam drive shaft is connected to the control mechanism. It is characterized in that it is connected to the crankshaft via an interlocking mechanism below.

According to a third aspect of the present invention, in addition to the first aspect, in the in-line four-cylinder internal combustion engine, both ends of the cam drive shaft are connected to the camshaft angular velocity variable mechanism, and a central portion of the cam drive shaft is located below the control mechanism. And is connected to the crankshaft via an interlocking mechanism.

According to a fourth aspect, in addition to the first aspect, the cam drive shaft is disposed in front of the internal combustion engine, and the input side of the control mechanism is disposed behind the internal combustion engine.

According to a fifth aspect of the present invention, in addition to the first aspect, the cam drive shaft is supported by a shaft supporting portion provided integrally with a cap member of a cam holder that supports the cam shaft.

[Action]

According to the first aspect of the present invention, since the camshaft angular velocity variable mechanism is disposed between the plurality of cylinders, the direction in which the cylinders are arranged, that is, the direction in which the cylinders are arranged, that is, compared to the case where the variable mechanism is provided outside one of the cylinders on one side, The axial width of the camshaft is reduced.

Further, since a control mechanism for controlling the camshaft angular velocity variable mechanism is disposed on the opposite side of the camshaft angular velocity variable mechanism with the one cylinder interposed therebetween, a drive system for rotating the camshaft, a control mechanism, There is no interference.

According to the second aspect, the cam drive shaft is provided separately from the cam shaft, one end of the cam drive shaft is connected to the camshaft angular velocity variable mechanism, and the other end of the cam drive shaft is connected to the control mechanism. Since the lower part is connected to the crankshaft via the interlocking mechanism, the control mechanism and the interlocking mechanism can be arranged in the vertical direction, and the axial width of the camshaft of the internal combustion engine can be shortened.

According to the third invention, in the in-line four-cylinder internal combustion engine, a cam drive shaft for rotating the cam shaft is provided separately from the cam shaft in parallel with the cam shaft, and both ends of the cam drive shaft are connected to the cam shaft. Since it is connected to the variable shaft angular velocity mechanism and the center part of the cam drive shaft is connected to the crankshaft via the interlocking mechanism below the control mechanism, the path for operating the left and right valve trains by the cam drive shaft; The components have the same structure, the intake and exhaust valves can be operated at the shortest distance, and common parts can be used.

According to the fourth aspect, since the cam drive shaft is disposed in front of the internal combustion engine and the input side of the control mechanism is disposed behind the internal combustion engine, the cam drive shaft and the input side of the control mechanism do not interfere with each other. According to the fifth aspect of the present invention, a connecting member such as a rotary cable connected to the control mechanism is protected by a carburetor or a frame which is usually arranged behind the internal combustion engine. Since the cam drive shaft is supported, the number of parts can be reduced and a fixing means such as a screw for fixing the holder can be omitted as compared with a case where a holder dedicated to supporting the cam drive shaft is newly provided.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of a cylinder head of an internal combustion engine cut along a plane passing through the center of a camshaft. As is apparent from this figure, the internal combustion engine shown here is of a series multi-cylinder type, and a cylinder head 1 is provided with camshafts 2 and 3 for intake and exhaust, respectively, so-called DOHC (double overhead camshaft). Type internal combustion engine. Although four cylinders 4 are provided, these cylinders are arranged in order from the left in FIG.
A, 2nd cylinder 4B, 3rd cylinder 4C, 4th cylinder 4D
Shall be called. The front and rear direction with respect to the vehicle body is the first
As shown in the figure.

In FIG. 2, reference numeral 10 denotes a crankshaft. The crankshaft 10 rotates from a timing gear 11 integrally formed with the crankshaft 10 to an idle gear 12 interposed therebetween.
The power is transmitted to the center gear 12c via a and 12b. The idle gears 12a and 12b are rotatably supported by an idle gear holder 13 bolted to the cylinder block 5. The center gear 12c is bolted to a projection of the cam drive shaft 15 so as to rotate integrally with the cam drive shaft 15. The cam drive shaft 15 is a cap member of a cam holder 16 that supports the exhaust cam shaft 3.
The cylinder head 1 is supported at the front center of the cylinder head 1 so as to be parallel to the camshafts 2 and 3 by a shaft support portion 17a formed integrally with the cylinder shaft 17. Cap member
17 is formed by integrally fixing the shaft support 17a to one side of the cap member 17b on the cylinder head 1 side as shown in FIGS. 4 (a) to 4 (c).

The idle gears 12a and 12b and the center gear 12c
Constitutes an interlocking mechanism 12 for transmitting the rotation of the crankshaft 10 to the cam drive shaft 15.

Side cam gears 18 are provided at both ends of the cam drive shaft 15.
Are spline-fitted. The side cam gear 18 meshes with a cam gear shaft 19 for exhaust, and the cam gear shaft 19 for exhaust meshes with a cam gear shaft 21 for intake via a cam idle gear 20. The cam idle gear 20 is rotatably supported by a gear shaft 22 supported by a cylinder head. The side cam gear 18, the cam gear shaft 19, the cam idle gear 20, and the cam gear shaft 21 include first and second cylinders 4A on the left and right,
4B and between the third and fourth cylinders 4C and 4D, respectively.

Further, the intake and exhaust camshafts 2, 3
Are provided one by one in each cylinder 4A, and are rotatably supported by the cam holder 16 provided in the cylinder head 1. Each of the camshafts 2 and 3 is disposed in the front-rear direction of the corresponding cylinder 4.

This internal combustion engine has a camshaft angular velocity variable mechanism that changes the angular velocity at the rotational position of the camshafts 2 and 3.
A variable valve timing mechanism S having a control mechanism 25 for controlling the camshaft angular velocity variable mechanism 25 is provided.

Describing the camshaft angular velocity variable mechanism 25,
A total of four mechanisms 25 are provided, two on the intake side and the other on the exhaust side, corresponding to the respective cam gear shafts 19 and 20. As shown in FIG. 5, both ends of an intermediate shaft 32 are rotatably fitted to large-diameter cylindrical portions 31 formed at ends of the camshaft 3 opposed to each other. The cam gear shaft 19 is fitted around the outer periphery of the central portion of the intermediate shaft 32. An eccentric shaft 33 is rotatably inserted through the inner periphery of the intermediate shaft 32. Eccentric part 34 of eccentric shaft 33
Is positioned so as to face a roller holding window 35 formed on the intermediate shaft 32 at predetermined intervals on the left and right. Also,
A roller 36 is fitted into the roller holding window 35,
An eccentric collar 37 is fitted on the outer peripheral surface of the envelope 36. An engaging projection 38 formed on the side of the cam gear shaft 19 is fitted into one of the holding grooves 39 extending in the radial direction of the eccentric collar 37, and the other holding groove 40 of the eccentric collar 37 is fitted into the end of the camshaft 2. The engagement protrusion 41 formed on the portion is engaged. In the camshaft angular velocity variable mechanism 25 configured as described above, the camshaft 3 is periodically displaced relative to the cam gear shaft 19 by the rotation position of the eccentric portion 34 of the eccentric shaft 33, and thus the camshaft 2 can be arbitrarily changed. This configuration is the same not only for the exhaust system but also for the intake system. The description of the intake system is omitted. The detailed mechanism of the camshaft angular velocity variable mechanism 25 will be described in Japanese Patent Application Laid-Open No. 63-1707.

On the other hand, the control mechanism 30 is
The camshaft angular velocity variable mechanism 25 is disposed on the opposite side of the cylinder so as not to interfere with the cylinder 25. Specifically, at the center of the cylinder head 1 in the center direction, it is provided at a position above the interlocking mechanism 12 so as to extend back and forth. That is, the eccentric shaft 33 is disposed across the second and third cylinders 4B and 4C of the cylinder head 1, and extends over both the eccentric shafts 33 and is orthogonal to the eccentric shaft 33. The shaft 50 is arranged to extend in the vehicle front-rear direction. The worm shaft 50 is rotatably supported by bearings 52 formed on the cylinder head cover 51 and the like, and worms 53 are formed at positions intersecting the two eccentric shafts 33, respectively. A worm gear 54 is formed on the eccentric shaft 33 at a position facing the worm 53, and the worm 53 and the worm gear 54 constitute a worm gear device 55. Note that the eccentric shaft 33 shown here is disposed so as to straddle the second cylinder 4B and the third cylinder 4C, and engages with the worm shaft 50 at the center thereof. The intermediate shaft may be connected to the shaft 33 so that the camshaft angular velocity variable mechanism 25 is engaged with the worm shaft 50.

The rear end of the worm shaft 50 constituting the control mechanism 30 protrudes outward from the wall of the cylinder head cover 51, and one end of a rotary cable 56 is connected to the protruding end. The other end of the rotary cable 56 is connected to a servomotor, which is controlled by a control unit (both not shown). The control unit receives inputs such as the rotation speed Ne of the internal combustion engine and the throttle opening θth,
A control signal is issued to the servomotor in response thereto.

In the variable valve timing mechanism having the above configuration, when the internal combustion engine is operating at a low speed, a servo motor (not shown) is rotated by a control signal from the control unit, and the rotation is controlled by the rotation cable 56. And transmitted to the eccentric shaft 33 via the control mechanism 30, and the eccentric shaft 33 is rotated and held at a position where the eccentric portion 34 is located faster than the intake / exhaust valve.
According to the principle similar to that of the variable valve timing mechanism described in Japanese Patent No. 1707, the opening start timing of the valve is delayed, the closing timing of the valve is advanced, and the valve overlap period is shortened.

Then, when the rotation speed of the internal combustion engine is increased to the highest rotation state, the eccentric portion 34 of the eccentric shaft 33 is rotated and held at a position closest to the valve by a control signal from the control unit, and the same as described above. According to the principle, the opening start timing of the valve is advanced, the closing timing of the valve is delayed, the valve overlap period is extended, and a state suitable for high-speed performance is achieved.

In the above embodiment, an example in which the present invention is applied to a parallel four-cylinder internal combustion engine has been described. However, the present invention is not limited to this, and the present invention is also applicable to a parallel two-cylinder internal combustion engine. In this case, one end of the cam drive shaft 15 is connected to the camshaft angular velocity variable mechanism 25 and the other end of the cam drive shaft 15 is connected to the crankshaft 10 below the control mechanism 30 via the interlocking mechanism 12. And Further, the present invention is not limited to a DOHC type internal combustion engine,
Applicable to SOHC type internal combustion engines.

〔The invention's effect〕

As described above, according to the present invention, the following excellent effects can be obtained.

According to the first invention, since the camshaft angular velocity variable mechanism is disposed between the plurality of cylinders, the direction in which the cylinders are lined up, that is, the cam, is different from the case where the variable mechanism is provided on one side outside any one of the cylinders. The width of the shaft in the axial direction can be reduced.

In addition, the control mechanism for controlling the camshaft angular speed variable mechanism is located on the opposite side of the camshaft angular speed variable mechanism with one cylinder in between, so interference with the drive system that rotates the camshaft is taken into account. The control mechanism can be arranged without performing.

Further, since the cam drive shaft is provided in parallel with the cam shaft, and this cam drive shaft is connected to the camshaft angular velocity variable mechanism and connected to the crankshaft, in an in-line multi-cylinder internal combustion engine, between each cylinder, It is possible to drive and control the variable camshaft angular velocity mechanism and the camshaft under the same conditions via the cam drive shaft, thereby performing high-precision control in which there is little deviation in the valve opening / closing timing between the cylinders. .

According to the second aspect, the cam drive shaft is provided separately from the cam shaft, one end of the cam drive shaft is connected to the camshaft angular velocity variable mechanism, and the other end of the cam drive shaft is connected to the control mechanism. Since the lower part is connected to the crankshaft via the interlocking mechanism, the control mechanism and the interlocking mechanism can be arranged vertically, and the width of the camshaft of the internal combustion engine in the axial direction can be shortened.

According to the third invention, a cam drive shaft for rotating the cam shaft is provided separately from the cam shaft in parallel with the cam shaft, and both ends of the cam drive shaft are connected to the cam shaft angular velocity variable mechanism and Since the central portion of the drive shaft is connected to the crankshaft below the control mechanism via an interlocking mechanism, the paths for operating the left and right valve mechanisms by the cam drive shaft and their components have the same structure, The intake and exhaust valves can be operated at the shortest distance, and common parts can be used.

According to the fourth aspect, since the cam drive shaft is disposed in front of the internal combustion engine and the input side of the control mechanism is disposed behind the internal combustion engine, it is possible to prevent interference between the cam drive shaft and the input side of the control mechanism. Can be avoided. Also,
Since a connecting member such as a rotating cable connected to the control mechanism is protected by a carburetor or a frame usually arranged behind the internal combustion engine, it is possible to prevent the rotating cable from being damaged.

According to the fifth aspect, since the cam drive shaft is supported by the shaft support portion provided integrally with the cap member of the cam holder, the number of parts is reduced as compared with the case where a dedicated holder for supporting the cam drive shaft is newly provided. The fixing member such as a screw for fixing the holder can be omitted.

[Brief description of the drawings]

1 to 5 show a variable valve timing mechanism according to the present invention. FIG. 1 is a transverse sectional view of a cylinder head, FIG. 2 is a longitudinal sectional view, and FIG. 3 is III in FIG. −III
4 (a) to 4 (b) are explanatory views showing a cam drive shaft holder, FIG. 4 (a) is a side view, FIG. 4 (b) is a roll-sectional view of FIG. 4 (a), Fig. 4 (b)
5 is an exploded perspective view showing the camshaft angular velocity variable mechanism. 1 ... cylinder head 2, 3 ... camshaft 4A-4D ... cylinder 5 ... cylinder block 10 ... crankshaft 12 ... interlocking mechanism 15 ... cam drive shaft 16 ... cam holder 17 ... cap member 17a ... ... shaft support 25 ... camshaft angular velocity variable mechanism 30 ... control mechanism 33 ... eccentric shaft (power transmission shaft) 50 ... worm shaft 55 ... worm gear

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 13/00 301 F01L 1/34

Claims (5)

(57) [Claims] In an in-line multi-cylinder internal combustion engine in which a plurality of cylinders are formed in series on a common cylinder block, a variable camshaft angular speed mechanism for changing an angular speed at a rotational position of a camshaft between the plurality of cylinders is provided. A control mechanism arranged for controlling the camshaft angle variable mechanism is provided,
A cam drive shaft for rotating the camshaft is provided in parallel with the camshaft separately from the camshaft, the camdrive shaft being arranged on the opposite side of the camshaft variable speed mechanism with the one cylinder interposed therebetween. A variable valve timing mechanism for an internal combustion engine, wherein a shaft is connected to the camshaft angular velocity variable mechanism and also to a crankshaft. 2. In an in-line two-cylinder internal combustion engine, one end of the cam drive shaft is connected to the variable camshaft angular velocity mechanism, and the other end of the cam drive shaft is interlocked with a crankshaft below the control mechanism. The variable valve timing mechanism for an internal combustion engine according to claim 1, wherein the variable valve timing mechanism is connected via a mechanism. 3. An in-line four-cylinder internal combustion engine, wherein both ends of said cam drive shaft are connected to said variable camshaft angular velocity mechanism, and a central portion of said cam drive shaft is linked to a crankshaft below said control mechanism. 2. The variable valve timing mechanism for an internal combustion engine according to claim 1, wherein the variable valve timing mechanism is connected via a connection. 4. The variable valve timing mechanism for an internal combustion engine according to claim 1, wherein the cam drive shaft is disposed in front of the internal combustion engine and an input side of the control mechanism is disposed behind the internal combustion engine. 5. The variable valve for an internal combustion engine according to claim 1, wherein said cam drive shaft is supported by a shout support portion provided integrally with a cap member of a cam holder supporting said cam shaft. Timing mechanism.