JPH10238360A - Cam shaft structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compact a device in a way that a dynamic damper, a cam sensor, and an auxiliary machine are disposed with high efficiency and suppress the generation of vibration due to the rotation fluctuation of a cam shaft and an increase in the load to a timing belt due to an increase in opening of an engine valve. SOLUTION: A dynamic damper 51 is mounted on one end face of cam shaft sprocket 34 for exhaust gas positioned on the tension side of a timing belt 36 and the sensing blade 62 of a cam sensor 61 is mounted on the outer end face. An actuator 71 for variable valve system is arranged as an auxiliary machine driven by a cam shaft 24 is arranged at the cylinder head 12 on the other end part side of a cam shaft 24 for exhaust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft structure constituting a valve operating mechanism for an intake / exhaust valve of an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, engine valves such as intake and exhaust valves are driven to open and close in accordance with rotation of a crankshaft.
Therefore, in general, a rotation transmission mechanism such as a timing belt drive system or a chain drive system is employed to transmit rotation between the crankshaft and the camshaft.

In recent years, in an internal combustion engine aiming at high output, as a technique for improving volumetric efficiency, an increase in a valve lift, an opening time, and an opening area of the engine valve have been considered. However, when such a method is used, the acceleration of the engine valve increases, and resonance occurs in the cam drive system depending on how the valve timing is set, so that the cam drive torque amplitude increases. The cam drive torque amplitude is related to the rotation fluctuation of the camshaft and is proportional to the load of the timing belt or the timing gear chain (hereinafter, simply referred to as the timing belt). That is, when the cam drive torque amplitude increases, for example, the load on the timing belt increases, especially around the resonance point, with respect to the rotation speed of the internal combustion engine (engine rotation speed), and the durability of the timing belt becomes a problem. .

On the other hand, it is considered that the fluctuation of the rotation of the camshaft due to the increase in the load is caused by the vibration caused by the torsion of the camshaft. Therefore, various proposals have been made to prevent the occurrence of vibrations due to such torsion of the camshaft.
No. 684, JP-A-59-73643 and the like.

Here, a general valve operating mechanism of an internal combustion engine will be described. FIG. 7 shows a schematic configuration of a general valve operating mechanism of an internal combustion engine.

In a general valve operating mechanism of an internal combustion engine, as shown in FIG. 7, a cylinder head 12 is fastened and fixed to a cylinder block 11 by bolts (not shown). , A piston 14 is fitted to be movable up and down. A combustion chamber 15 is formed by the cylinder block 11, the cylinder head 12, and the piston 14. The combustion chamber 15 is connected to an intake port 16 and an exhaust port 17, and the intake port 16 and the exhaust port 17 are connected to an intake valve 18 and an exhaust port. The front end of the valve 19 faces, and the combustion chamber 15 and each port 16, 1
7 can be opened and closed. A crankshaft 20 is rotatably disposed below the cylinder block 11. A large end of a connecting rod 22 is connected to an eccentric portion of the crankshaft 20 by a crankpin 21. A piston 14 is mounted.

An intake camshaft 23 is provided above the cylinder head 12 so as to be parallel to the crankshaft 20.
And an exhaust camshaft 24 are rotatably supported, and each of the intake cams 25 has a predetermined lift amount for each cylinder.
And the exhaust cam 26 are integrally formed. Rocker arms 27 and 28 are rotatably mounted on the cylinder head 12, and each of the rocker arms 27 and 28 is
5 is driven by the exhaust cam 26 and one end thereof is in contact with upper ends of the intake valve 18 and the exhaust valve 19 urged upward by valve springs 29 and 30. Further, a fuel injection valve 31 for injecting fuel into the intake port 16 is mounted on the intake side of the cylinder head 12.
A spark plug 32 whose front end faces inside the combustion chamber 15 is mounted.

A crankshaft sprocket 33 is fixedly connected to one end of the crankshaft 20, and camshaft sprockets 34, 35 are fixedly connected to one end of each of the camshafts 23, 24. An endless timing belt 36 is stretched around 33, 34, 35.
The crankshaft 20 and each camshaft 23,
And 24 rotate synchronously. In addition, 37 is an idler pulley, 38 is a water pump pulley, and 39 is a tensioner pulley.

Therefore, when the crankshaft 20 is driven to rotate, the piston 14 reciprocates in the cylinder 13 via the connecting rod 22. On the other hand, the crankshaft 20
Is transmitted to the respective camshafts 23 and 24 via the sprocket 33, the timing belt 36 and the sprockets 34 and 35, and the respective camshafts 23 and 2 are transmitted.
4 are driven synchronously to rotate. Then, each camshaft 2
The cams 25 and 26 open and close the intake valve 18 and the exhaust valve 19 via the rocker arms 27 and 28 by the rotational drive of the fuel injection valves 3 and 24. At this time, the fuel injection valve 31 injects fuel into the intake port 17 and burns. Intake, compression,
Each process of explosion and exhaust is repeated. That is, when the intake valve 18 is opened, air-fuel mixture is introduced into the combustion chamber 15 from the intake port 16, and the air-fuel mixture compressed by the rise of the piston 14 is ignited from the ignition plug 32, exploded, and then exhausted. Exhaust gas is exhaust port 1 when opening 19
The gas is exhausted from the outside.

In the operation of such a valve operating mechanism, the rotational driving force of the crankshaft 20 is applied to the timing belt 3.
6. The power is transmitted to the respective camshafts 23, 24 via the respective camshaft sprockets 34, 35, and the respective cams 25, 26 of the camshafts 23, 24 are transmitted to the respective valves 18, 26.
When the valve 19 is pushed down (the valves 18 and 19 are opened), the urging forces of the valve springs 29 and 30 and the valves 18 and 1
The drive torque is generated by the inertial force acting on 9. Assuming that this is a positive drive torque, when the valves 18 and 19 are pushed back by the urging force of the valve springs 29 and 30 after closing the maximum lift (close the valves 18 and 19), a negative drive torque is generated by the same force. I do. Accordingly, when the respective camshafts 23 and 24 rotate, positive drive torque and negative drive torque are generated alternately, and thus the sprockets 34 and 35 undergo rotation fluctuations.

As described above, each time the camshafts 23 and 24 rotate and the cams 25 and 26 open and close the valves 18 and 19 through the rocker arms 27 and 28, the rotation of the camshafts 23 and 24 changes. Acts, and the camshafts 23 and 24 generate vibrations due to rotational fluctuations. And the camshafts 23, 2
If the vibration of No. 4 and the natural vibrations of the camshafts 23 and 24 and the camshaft sprockets 34 and 35 match in terms of frequency, a further resonance will occur and the vibration will increase.

When the vibration caused by the rotation fluctuation occurs, a tensile force is repeatedly applied to the timing belt 36 and the like between the crankshaft sprocket 33 and the camshaft sprockets 34, 35, and this timing belt For 36, etc., the load becomes abnormal and an undesirable situation occurs. Therefore, in order to remove the abnormal load on the timing belt 36, means must be taken to prevent the camshafts 23 and 24 from generating vibrations, and various proposals as described above have been made.

That is, Japanese Unexamined Utility Model Publication No. Hei 6-23684 discloses that a crankshaft sprocket fixed to a crankshaft and a camshaft sprocket fixed to one end of a camshaft are connected by a timing belt. In the internal combustion engine that transmits the rotational motion of the crankshaft to the camshaft, a dynamic damper that suppresses vibration caused by torsion of the camshaft is provided at the other end of the camshaft without the camshaft sprocket. It is arranged to effectively suppress vibration.

[0014] Japanese Patent Application Laid-Open No. S59-73643 discloses a crankshaft sprocket and a camshaft sprocket fixed to one end of a camshaft connected by a timing belt to control the rotational movement of the crankshaft. In an internal combustion engine transmitting to a camshaft,
At the end of the camshaft, a weight unit having an annular weight and an annular weight disposed around an annular member via an elastic coupling body is attached.

[0015]

Incidentally, in the above-mentioned internal combustion engine, in order to suppress vibration caused by rotation fluctuation of the camshaft, a damper elastic body is mounted on the camshaft or a dynamic damper is provided. Or arrange
Although an elastic coupling body is provided, in the internal combustion engine, in addition to a crank angle sensor for detecting a crank angle, a cylinder discrimination sensor (hereinafter, referred to as a cam cam sensor) ) Must be provided. Also, there are cases where it is necessary to dispose auxiliary equipment such as an actuator for operating the variable valve mechanism and a fuel injection pump in a required part of the internal combustion engine. Considering the structure of the internal combustion engine, how to arrange such various devices becomes an issue.

However, in the above-mentioned publications, the vibration of the camshaft is simply suppressed by disposing a damper elastic body, a dynamic damper, and an elastic coupling body on the camshaft. None of them take into account the arrangement of the crank angle sensor, the cam cam sensor, and the accessories. Therefore, according to the prior art described in each of the above publications, the crank angle sensor, the cam angle sensor,
In addition to securing the arrangement of accessories and the like, it is not only impossible to effectively suppress the vibration of the camshaft, but also it is not possible to arrange the dynamic damper and the like compactly.

The present invention is intended to solve such a problem. In order to reduce the size of the apparatus by efficiently disposing a dynamic damper, a cam sensor, an auxiliary device, and the like, the vibration caused by the rotational fluctuation of the camshaft is reduced. Further, it is an object of the present invention to provide a camshaft structure of an internal combustion engine in which an increase in load on a timing belt due to an increase in acceleration of an engine valve is suppressed and detection accuracy of a sensor is improved.

[0018]

According to the present invention, there is provided a camshaft structure for an internal combustion engine according to the present invention, wherein first and second camshafts are rotatably supported by a cylinder head for driving a valve of the internal combustion engine. 2 camshafts, and first and second camshafts mounted at one end of the first and second camshafts, respectively.
A camshaft sprocket, a crankshaft sprocket mounted at one end of a crankshaft of the internal combustion engine, and an endless timing belt wound around the first and second camshaft sprockets and the crankshaft sprocket. In a camshaft structure for an internal combustion engine, a dynamic damper is mounted on one end surface of one of the first and second camshaft sprockets located on the tension side of the timing belt, and the other camshaft is mounted on one end surface of the camshaft sprocket. An auxiliary machine having a cam sensor mounted on the other end surface of the sprocket and a cylinder head on the other end side of each of the first and second camshafts, which can be driven by one of the first and second camshafts. Is provided.

Therefore, the dynamic damper and the cam sensor can be efficiently arranged by mounting the dynamic damper on one end surface of the cam shaft sprocket on the tension side of the timing belt and mounting the cam sensor on the other end surface. Therefore, it is possible to suppress the increase in the load on the timing belt due to the vibration caused by the rotation fluctuation of the camshaft and the increase in the acceleration of the engine valve, to improve the detection accuracy of the sensor, and to increase the other end of each camshaft. By providing an auxiliary device that can be driven by this camshaft in the cylinder head on the side, the auxiliary device can be efficiently disposed, and the device can be made compact.

The camshaft structure for an internal combustion engine according to a second aspect of the present invention is configured such that a detection blade of the cam sensor is mounted on an end surface of the one camshaft sprocket facing the cylinder head, and the camshaft is mounted on the cylinder head. A detection unit of the cam sensor for detecting a blade to be detected is mounted.

Therefore, the detection blade of the cam sensor is mounted on the end face of the camshaft sprocket, and the detection section of the cam sensor is mounted on the position facing the cylinder head.
The cam sensor can be efficiently and easily arranged, and the detection accuracy of the sensor can be improved.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view of an internal combustion engine showing a camshaft structure of the internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a side view of the internal combustion engine of the first embodiment, and FIG. 4 shows a cross section taken along line IV-IV of FIG. Members having the same functions as those described in the related art are denoted by the same reference numerals, and redundant description will be omitted.

The internal combustion engine (hereinafter referred to as the engine) of the present embodiment has four cylinders and a double overhead camshaft (D) having two camshafts.
OHC) type. In the camshaft structure of the internal combustion engine according to the present embodiment, as shown in FIGS. 1 and 2, a cylinder head 12 is fastened and fixed on a cylinder block (not shown), and four cylinders formed with the cylinder block are formed. A piston (not shown) is fitted inside 13 so as to be vertically movable. A valve mechanism is provided above each of the cylinders 13. That is, an intake camshaft 23 and an exhaust camshaft 24, which are parallel to each other, are rotatably supported on the upper portion of the cylinder head 12, and a pair of intake cams 25 each having a predetermined lift amount for each cylinder and an exhaust camshaft are provided. The cam 26 is formed integrally. The cylinder head 12 has a rocker arm 27,
28 are rotatably mounted, and each rocker arm 27,
Reference numeral 28 is driven by the intake cam 25 and the exhaust cam 26, and one end thereof is in contact with the upper end of the intake valve 18 and the exhaust valve 19 urged upward by a valve spring (not shown). Further, a crankshaft 20 is rotatably disposed below the cylinder block, and the crankshaft 20 is connected to a piston via a connecting rod (not shown).

A crankshaft sprocket 33 is fixed to one end of the crankshaft 20 by a fixing bolt 41, and camshaft sprockets 34 and 35 are fixed to one end of each of the camshafts 23 and 24 by fixing bolts 42. , 43, and an endless timing belt 36 is stretched between the sprockets 33, 34, 35. An idler pulley 37 and a water pump pulley 38 are in contact with the timing belt 36, and the timing belt 36
Can be rotated. Further, a tensioner pulley 39 is pressed against the timing belt 36 by a tensioner 40 to prevent the timing belt 36 from being loosened.

Accordingly, the crankshaft 20 and each of the camshafts 23 and 24 are rotated synchronously by the timing belt 36. At this time, the camshaft sprockets 34 and 35 provided at the ends of the camshafts 23 and 24 receive the rotational force of the crankshaft sprocket 33 through the timing belt 36. Since the pulling sprocket 35 is constantly pulled, the sprocket 34 on the feed side (loose side) is used.
Than the crankshaft sprocket 33. That is, the exhaust camshaft 24 is more suitable for the crankshaft 2 than the intake camshaft 23.
This means that the rotation phase of 0 is transmitted with high accuracy. Therefore, in the present embodiment, the exhaust camshaft 24
On the side, a dynamic damper 51, a cam sensor 61, and an actuator 71 for a variable valve mechanism as an auxiliary machine are provided.

That is, the dynamic damper 51 has an annular shape, and includes an innermost mounting cylinder 52 and an elastic member 53 made of an annular rubber, a synthetic resin or the like fixed to the outer periphery of the mounting cylinder 52.
And an outer annular weight 54 formed of a weight ring made of iron or the like fixed to the outer periphery of the elastic member 53. Dynamic damper 5 configured as above
1 is in contact with the outer end surface of the camshaft sprocket 35 for exhaust and is stopped and locked by the fixing pin 55, and is fixed to one end of the camshaft 24 by the fixing bolt 43 together with the camshaft sprocket 35. ing.

The cam sensor 61 detects the crank angle and determines the cylinder discrimination in order to set the ignition timing, fuel injection timing, fuel injection amount, etc. of the engine, and a sensing blade which rotates integrally with the camshaft 24. 62
And a magnet-type cam sensor detector 63 for detecting the sensing blade 62. As shown in FIGS. 3 and 4, an annular sensing blade 62 is fixed to an inner end surface of the exhaust camshaft sprocket 35 by a plurality of fixing screws 64, and the sensing blade 62 is attached to the cylinder head 12 side. The detection part 62a which is bent to be formed integrally is formed. On the other hand, on the side wall of the cylinder head 12 facing the inner end surface of the camshaft sprocket 35, the mounting projection 12
The sensor body 65 of the cam sensor 61 is attached to the attachment projection 12a by a bolt 66. The sensor body 65 is attached to the sensor body 65 so as to extend to the camshaft sprocket 35 side. A part 63 is provided.

Therefore, the sensing blade 62 rotates together with the camshaft sprocket 35 (camshaft 24), and the cam sensor detecting unit 63 sets the sensing blade 62
The rotation angle of the camshaft 24, that is, the crank angle, is detected based on the position where the detected portion 62a is detected, and is output as a detection signal to a control device (not shown) of the engine.

Further, as shown in FIG. 1, the other end of each of the camshafts 23, 24, that is, the cylinder head 12 on the opposite side to the side on which the respective camshaft sprockets 34, 35 are fixed, is variably moved. A valve mechanism actuator 71 is mounted. This variable valve mechanism aims to increase the torque at low and medium speeds and increase the output at high speed by continuously changing the valve timing according to the engine speed. The operation of this variable valve mechanism is controlled.

Accordingly, the camshaft structure of the internal combustion engine according to the first embodiment of the present invention is configured as described above. When the crankshaft 20 is driven to rotate, the rotational driving force of the crankshaft 20 is applied to the sprocket 33 and the timing. The power is transmitted to the respective camshafts 23 and 24 via the belt 36 and the sprockets 34 and 35, and the respective camshafts 23 and 24 are rotationally driven in synchronization. Then, the respective cams 25, 2 are driven by the rotation of the respective camshafts 23, 24.
6, the intake valve 18 and the exhaust valve 19 are opened and closed via rocker arms 27 and 28. At this time, a fuel injection valve (not shown) injects fuel into an intake port to cause intake, compression, explosion, and exhaust in the combustion chamber. The process is repeated.

A dynamic damper 51 is mounted on the sprocket 35 of the exhaust camshaft 24. During the operation of the engine, the vibration caused by the rotation fluctuation generated on the camshaft 24 causes the dynamic damper 5 to rotate.
As a result, even if the cam drive torque amplitude increases due to an increase in engine speed and the like, and the load on the timing belt 36 increases, the camshaft 23, The increase in the load in the vicinity of the 24 resonance point can be greatly reduced. By mounting the cam sensor detector 63 of the cam sensor 61 on the tension-side cam shaft 24 (cam shaft sprocket 35) rotating with higher precision, the cam sensor 61 can accurately detect the cam angle and determine the cylinder. Thus, the ignition timing, fuel injection timing, fuel injection amount, and the like of the engine can be accurately set, and the engine performance can be improved.

Further, a dynamic damper 51 and a cam sensor 61 are mounted on each end face of a camshaft sprocket 35 fixedly connected to one end of the camshaft 24, and an actuator 71 for a variable valve mechanism as an auxiliary machine is mounted on the camshaft. By arranging them on the cylinder head 12 at the other end of the cylinder 24, the members can be efficiently arranged and the whole engine can be made compact.

FIG. 5 is a plan view of an internal combustion engine showing a camshaft structure of an internal combustion engine according to a second embodiment of the present invention. FIG. 6 is an internal combustion engine showing a camshaft structure of an internal combustion engine according to a third embodiment of the present invention. 2 shows a plan view of the engine. Note that the first
Members having the same functions as those described in the embodiment are denoted by the same reference numerals, and redundant description will be omitted.

The camshaft structure of the internal combustion engine according to the second embodiment has a dynamic damper 51 and a cam sensor 61 provided at one end of the exhaust camshaft 24 as shown in FIG. An actuator 71 for a variable valve mechanism as an auxiliary machine is provided at the other end, and a fuel injection pump 81 is provided at the other end of the intake camshaft 23.
Is provided.

That is, in the engine valve operating mechanism, as described above, the rotation of the crankshaft 20 is transmitted more accurately to the exhaust camshaft 24 than to the intake camshaft 23. 51 is fixed to the camshaft sprocket 35 together with the camshaft sprocket 35 in a state of contacting the outer end surface of the camshaft sprocket 35 for exhaust and being stopped and locked by the fixing pin 55.
3 is fixed to one end of the camshaft 24. The magnet type cam sensor 61 detects the crank angle and detects the cylinder discrimination in order to set the ignition timing, fuel injection timing, fuel injection amount, etc. of the engine. The cam sensor detector 63 is attached to a side wall of the cylinder head 12 facing the inner end surface of the cam shaft sprocket 35 while the sensing blade 62 is fixed to the cylinder head 12. Further, an actuator 71 for a variable valve mechanism as an accessory is mounted on the cylinder head 12 on the other end side of the exhaust camshaft 24, and the intake camshaft 2
A fuel injection pump 81 as an auxiliary device is mounted on the cylinder head 12 at the other end of the cylinder head 3 adjacent to the actuator 71 for the variable valve mechanism.

As shown in FIG. 6, the camshaft structure of the internal combustion engine according to the third embodiment has a dynamic damper 51 and a cam sensor 61 provided at one end of an exhaust camshaft 24, while an intake camshaft is provided. An actuator 71 for a variable valve mechanism as an auxiliary machine is provided on the other end side of the fuel cell 23, and a fuel injection pump 81 is provided on the other end side of the exhaust camshaft 24.

Accordingly, the camshaft structures of the internal combustion engines according to the second and third embodiments of the present invention are configured as described above, and the vibration caused by the rotation fluctuation generated on the camshaft 24 during the operation of the engine is dynamic. Since the damper 51 absorbs and reduces the torque, even if the cam drive torque amplitude increases due to an increase in engine speed or the like and the load on the timing belt 36 increases due to this, the resonance point of the camshafts 23 and 24 is increased. The load increase in the vicinity can be greatly reduced. Then, the tension side camshaft 24 (camshaft sprocket 35) that rotates with higher precision.
By mounting the cam sensor detection unit 63 of the cam sensor 61 to the cam sensor 61, it is possible to accurately detect the crank angle by the cam sensor 61, and accurately set the ignition timing, the fuel injection timing, the fuel injection amount, etc. of the engine. Performance can be improved. Furthermore, dynamic damper 5
1 and a cam sensor 61 are mounted on each end face of a camshaft sprocket 35 fixedly connected to one end of the camshaft 24, and an actuator 71 for a variable valve mechanism as an auxiliary machine and a fuel injection pump 81 are connected to the camshaft 23, 24
By disposing the components on the cylinder head 12 on the other end side, each member can be disposed efficiently and the whole engine can be made compact.

The camshaft structure of the internal combustion engine according to the present invention is not limited to the above-described embodiments.
In each of the embodiments, the valve mechanism by the timing belt 36 and the sprockets 33, 34, 35 has been described. However, a valve mechanism by a timing gear chain and a sprocket may be used, whereby the dynamic damper 51 and the cam sensor 61 are efficiently distributed on the space. Each function can be exerted more effectively while being installed, and vibrations and the like generated on the camshafts 23 and 24 during the rotation drive can be reliably suppressed, and the life of the timing belt and the chain is improved. This has the effect of making the operating noise quieter.

[0040]

As described above in detail in each embodiment, according to the camshaft structure of the internal combustion engine of the present invention, the dynamic damper is mounted on one end face of the camshaft sprocket located on the tension side of the timing belt. The cam sensor is mounted on the other end surface of the camshaft, and an auxiliary device that can be driven by the camshaft is provided on the cylinder head on the other end side of each camshaft. By absorbing and reducing the vibrations generated by the dynamic damper, the load applied to the timing belt can be reduced, the life of the timing belt can be improved, and the operating noise of the internal combustion engine can be suppressed. Can be
Further, the cam angle can be accurately detected and the cylinder can be determined by the cam sensor, and the ignition timing, the fuel injection timing, and the fuel injection amount of the internal combustion engine can be accurately controlled, and the performance of the internal combustion engine can be improved. Further, by mounting a dynamic damper on one end of a camshaft sprocket fixed to one end of the camshaft and a cam sensor on the other end, an auxiliary machine is arranged on a cylinder head on the other end of the camshaft. By arranging each member efficiently, the whole engine can be made compact.

According to the camshaft structure for an internal combustion engine according to the second aspect of the present invention, the detected blade of the cam sensor is mounted on the end face of the camshaft sprocket facing the cylinder head, and the detected blade is mounted on the cylinder head. Since the detection section of the cam sensor for detection is mounted, the cam sensor can be efficiently and easily arranged, and the detection accuracy of the sensor can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of an internal combustion engine showing a camshaft structure of the internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a side view of the internal combustion engine of the first embodiment.

FIG. 3 is a detailed view of a cam sensor mounting portion.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a plan view of an internal combustion engine showing a camshaft structure of the internal combustion engine according to a second embodiment of the present invention.

FIG. 6 is a plan view of an internal combustion engine showing a camshaft structure of the internal combustion engine according to a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a valve mechanism of a general internal combustion engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Cylinder head 13 Cylinder 18 Intake valve 19 Exhaust valve 20 Crankshaft 23 Intake camshaft 24 Exhaust camshaft 25 Intake cam 26 Exhaust cam 27, 28 Rocker arm 33 Crankshaft sprocket 34, 35 Camshaft sprocket 36 Timing belt 51 Dynamic damper 61 Cam Sensor 62 Sensing Blade 63 Sensor Detector 71 Actuator for Variable Valve Mechanism (Auxiliary Equipment) 81 Fuel Pump (Auxiliary Equipment)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G01D 5/245 G01D 5/245 X

Claims (2)

[Claims] 1. A first and second camshaft rotatably supported by a cylinder head for driving a valve of an internal combustion engine, and a first and second camshafts mounted at one end of each of the first and second camshafts. And a second camshaft sprocket;
A camshaft for an internal combustion engine, comprising: a crankshaft sprocket mounted at one end of a crankshaft of the internal combustion engine; and an endless timing belt wound around the first and second camshaft sprockets and the crankshaft sprocket. In the structure, a dynamic damper is mounted on one end surface of one of the first and second camshaft sprockets located on the tension side of the timing belt,
A cam sensor is mounted on the other end surface of the one camshaft sprocket, and one of the first and second camshafts is attached to a cylinder head on the other end side of each of the first and second camshafts. A camshaft structure for an internal combustion engine, comprising a drivable accessory. 2. A camshaft structure for an internal combustion engine according to claim 1, wherein a detection blade of said cam sensor is mounted on an end surface of said one camshaft sprocket facing said cylinder head, and said cylinder head is provided with said detection blade. A camshaft structure for an internal combustion engine, wherein a detection unit of the cam sensor for detecting a detection blade is mounted.