JPH06129214A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a valve system for an internal combustion engine by enhancing the follow-up of a valve lifter with respect to a cam so as to contribute to the restraint to abnormal behavior of a valve, such as jumping of the valve. CONSTITUTION:An oval shape cam 17 incorporated to a cam shaft 1 has an intermediate disk 18 which is held between clamping disc parts 19 made of ferromagnetic materials. In a high rotational speed range, a centrifugal force acting upon a sphere of a speed responding mechanism 27 overcomes the urging force of a cone spring 27b, and accordingly, a movable shaft 2 is moved in the direction of the arrow X2 so that a permanent magnet 22 faces the intermediate disc 18. In this condition, magnetic fluxes from a magnetic pole of the permanent magnet 22 passes radially of the clamping disc part 19 of the cam 17, and reach the valve lifter 3. Accordingly, a looped magnetic path M3 is established. The magnetic path M3 connect the cam surface of the cam 17 and a pressing face 30 of the valve lifter 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve mechanism for an internal combustion engine.

[0002]

2. Description of the Related Art A valve operating mechanism of an internal combustion engine is one that opens and closes a port of a combustion chamber of an internal combustion engine by operating valves for intake and exhaust when a cam is rotated by rotational driving of a cam shaft. However, when the rotation speed of the cam becomes considerably high,
The followability of the valve to the cam is reduced, and abnormal behavior such as jumping of the valve floating in the air and bouncing of the valve is likely to occur.

Particularly when the spring constant of the valve spring for urging the valve in the valve closing direction is small and its urging force is weak, the urging force of the valve spring becomes the inertia of the valve when the internal combustion engine is in the high speed rotation region. It is easy to lose force and cause abnormal behavior such as jumping. In order to suppress abnormal behavior such as jumping, it is sufficient to increase the spring constant of the valve spring, but this increases frictional resistance of the cam and is not preferable in terms of smooth operability of the cam.

Further, as a valve operating mechanism of an internal combustion engine for preventing abnormal behavior such as jumping of a valve, there is disclosed in Japanese Unexamined Patent Publication No. 2-125.
As disclosed in Japanese Laid-Open Patent Publication No. 904, an electromagnet is provided on a valve seat that is in close contact with the valve when the valve is in a fully closed state, a sensor that detects a closed valve section of a cam is provided, and the electromagnet is activated based on a signal from the sensor. A method of exciting is known. In this structure, in the high speed rotation range, the magnetic attraction of the electromagnet is generated to cause the valve seat to suck the valve, thereby suppressing abnormal behavior such as jumping of the valve in the high speed rotation range.

Further, as a valve mechanism for an internal combustion engine using a magnet, as disclosed in Japanese Patent Application Laid-Open No. 2-221608, the valve is provided in a coiled valve spring for urging the valve in a valve closing direction. There is known a system in which a permanent magnet is provided at one end of the spring in the axial direction and an electromagnet is provided at the other end of the valve spring in the axial direction. In this structure, the magnetic poles of the electromagnet and the permanent magnet are faced to each other to cause a magnetic attraction action based on the opposite pole pair faces and a magnetic repulsion action based on the same pole facets, thereby adjusting the spring constant of the valve spring.

[0006]

The present invention is different from the method according to the above-mentioned publication, and by adopting a method of forming a magnetic path connecting the cam surface of the cam and the pressing surface of the driven body, the driven body for the cam is It is an object of the present invention to provide a valve operating mechanism of an internal combustion engine that can improve the followability of the engine and contribute to suppressing abnormal behavior such as valve jumping.

[0007]

A valve mechanism for an internal combustion engine according to the present invention includes a cam shaft rotatably provided in an internal combustion engine having a combustion chamber and a valve for opening and closing a port of the combustion chamber, and a cam shaft. A cam that is held and rotates with the rotation of the cam shaft, and a pressing surface that is pressed by the cam surface of the cam, and a driven body that follows the rotation of the cam to operate the valve, and a cam surface of the cam and the driven body. It is characterized in that it is constituted by a magnet that forms a magnetic path connecting to the pressing surface and enhances the followability of the driven body to the cam.

In the present invention, the driven body is driven according to the rotation of the cam. The magnet forms a magnetic path that connects the cam surface of the cam and the pressing surface of the driven body, and can be a permanent magnet or an electromagnet. Known permanent magnets such as rare earth magnets, cast magnets, and sintered magnets can be used as the permanent magnets. In the present invention, it is preferable to provide a switching means for switching between the form of forming the magnetic path and the form of not forming the magnetic path according to the rotational speed of the internal combustion engine.

[0009]

[Operation] The cam rotates as the cam shaft rotates. As a result, the driven body is driven, the valve operates, and the port of the combustion chamber of the internal combustion engine is opened / closed. Since the magnet forms a magnetic path connecting the cam surface of the cam and the pressing surface of the driven body, the operability of the cam surface of the cam and the pressing surface of the driven body is ensured. The followability of the follower increases.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. This example is applied to a direct-drive type OHC internal combustion engine. (Structure of Embodiment) FIGS. 1 and 3 show a valve mechanism. FIG. 2 shows the main part of FIG.

The cam shaft 1 shown in FIG. 1 is rotatably provided on a cylinder head of an internal combustion engine. The camshaft 1 closes the camshaft main body 12 having a journal portion 10 and a hollow chamber 11 extending in the axial direction, a timing pulley 14 continuously provided at an end of the camshaft main body 12 and having a working chamber 13, and the working chamber 13. A lid 15 having a step 15a is also provided. A large number of egg-shaped cams 17 are held on the cam shaft 1. The cam 17 is formed of an intermediate plate 18 made of a non-magnetic material, and a holding plate portion 19 which is integral with the cam shaft body 12 and which projects in the radial direction of the cam shaft body 12 and sandwiches the intermediate plate 18. The form of connection between the intermediate plate 18 and the sandwich plate part 19 can be selected as appropriate, but means for increasing the mechanical locking force due to unevenness, means for casting the intermediate plate 18 around the sandwich plate part 19, welding means, etc. can be adopted. . The non-magnetic material forming the intermediate plate 18 is meant to include a weak magnetic material having a low magnetic susceptibility and a paramagnetic material, and non-magnetic metals such as aluminum alloys and austenitic stainless steel, ceramics such as alumina and silicon nitride, and resins. And the like. When the intermediate plate 18 is made of aluminum, ceramics, or resin, weight reduction can be expected. When the intermediate plate 18 is made of resin, the resin easily fulfills the vibration damping function, which is advantageous for suppressing the vibration of the camshaft 1. The cam shaft body 12 and the holding plate portion 19 are made of a ferromagnetic material, that is, iron or an iron-based alloy.

The reason why the intermediate plate 18 made of a non-magnetic material is arranged inside the cam 17 is as follows. That is, FIG.
In the description using the U-shaped magnet 100 in the above, when the magnetic pole of the U-shaped magnet 100 is attracted to the magnetic body 101, U
The magnetic flux from the magnetic pole of the C-shaped magnet 100 does not easily reach the attracted body 103 made of a ferromagnetic material, and the loop-shaped magnetic path M1.
Does not reach the object 103 to be attracted, and the attraction force for magnetically attracting the object 103 to be attracted is extremely small. On the other hand, the non-magnetic material 10
When 5 is arranged, the magnetic flux from the magnetic poles of the U-shaped magnet 100 avoids the non-magnetic body 105 and thus is easy to fly.
A magnetic path M2 in a loop shape is formed which easily reaches the attracted body 103 made of a ferromagnetic material and penetrates the attracted body 103, whereby the attraction force for the U-shaped magnet 100 to magnetically attract the attracted body 103 is large. Become. This is the reason why the intermediate plate 18 made of a non-magnetic material is arranged.

As is well known, the timing pulley 14
A belt and a chain are installed on the shaft, and the driving force of the crankshaft is transmitted to the timing pulley 14 to rotate the camshaft 1. As shown in FIG. 1, the hollow chamber 1 of the camshaft 1
1, the movable shaft 2 is along the cam shaft 1, that is, the arrows X1, X
It is fitted so as to be movable in two directions. The movable shaft 2 includes a large diameter portion 21 that protrudes in the radial direction and has an inclined surface 20, and a large number of permanent magnets 22 that are arranged in parallel in the axial direction. The magnetic poles of the permanent magnet 22, N pole and S pole, are arranged in the axial direction of the movable shaft 2. Here, as shown in FIG. 1, the N poles of the adjacent permanent magnets 22 are set to face each other, and the S poles are set to face each other. This is because it is effective to fly the magnetic flux in the radial direction of the cam shaft 1.

An oil passage 25 is formed by the outer peripheral surface of the movable shaft 2 and the inner peripheral surface of the cam shaft body 12. The oil of the internal combustion engine is supplied to the oil passage 25, and the oil secures the smooth movement of the movable shaft 2 and the cooling of the permanent magnet 22. Reference numeral 26 denotes an oil supply passage formed in the journal portion 10 of the camshaft 1 for supplying oil to a bearing holding the journal portion 10. In the working chamber 13 of the timing pulley 14, a speed response mechanism 27 as a switching means is arranged. The speed response mechanism 27 includes a sphere 27a inserted between the lid portion 15 and the large diameter portion 21 and a cone spring 27 for urging the large diameter portion 21 in the arrow X1 direction.
and b. Here, when the rotational speed of the cam shaft 1 increases and the centrifugal force acting on the sphere 27a increases, the sphere 27
a moves in the centrifugal direction and climbs the inclined surface 20, whereby the movable shaft 2 moves in the direction of the arrow X2 against the biasing force of the cone spring 27b, and as a result, as shown in FIG. Faces the intermediate board 18. When the rotational speed of the cam shaft 1 decreases and the centrifugal force acting on the ball 27a becomes smaller, the urging force of the cone spring 27b causes the ball 27a to move in the centripetal direction as shown in FIG. 2 is returned in the direction of the arrow X1, and as a result, the permanent magnet 22 is separated from the intermediate plate 18 by the dimension L5 as shown in FIG.

Further, a valve lifter 3 as a driven body is provided. The valve lifter 3 is also called a tappet, has a cylindrical shape, and converts the rotational movement of the cam shaft 1 into a linear movement. The valve lifter 3 is made of a ferromagnetic material, that is, iron alloy. The valve 4 closes the port of the combustion chamber of the internal combustion engine and includes a valve stem 40, a valve head 41, and a valve face 42. The valve stem 40 is equipped with a seat 4a. The valve spring 5 is interposed between the seat portion 6a of the cylinder head 6 of the internal combustion engine and the seat seat 4a. The valve spring 5 urges the valve 4 in the valve closing direction, that is, the arrow Y1 direction to bring the valve face 42 into close contact with the valve seat of the port of the combustion chamber and to urge the pressing surface 30 of the valve lifter 3 in the arrow Y1 direction. And has a function of pressing against the cam surface 170 of the cam 17.

Now, FIG. 5 is a characteristic diagram showing a valve lift of a valve train of a general internal combustion engine. In FIG. 5 (A), the characteristic line α shows the lift curve of the cam 17, the characteristic line β shows the curve of the inertia force (F = ma) based on the acceleration change of the cam 17, and the characteristic line γ shows the spring of the valve spring 5. Indicates the load. Here, FIG. 5B shows a state before the start of lift, that is, a state in which a clearance E1 is formed between the cam surface 170 of the cam 17 and the pressing surface 30 of the valve lifter 3. Since the clearance E1 is used to increase the magnetic resistance, the magnetic attraction force in this state decreases. FIG. 5C shows the start of lift when the cam surface 170 starts to press the pressing surface 30. FIG. 5D shows a state in which the cam surface 170 further presses the pressing surface 30. FIG. 5 (E) shows the cam surface 17
The nose portion 171 at the tip of 0 pushes the pressing surface 30 at the maximum lift time.

By the way, in understanding the characteristics of the valve operating mechanism of the internal combustion engine, the dynamic effect must be taken into consideration. Especially when the internal combustion engine is in the high speed range, the dynamic effect must be taken into consideration. In this case, as shown in FIG.
The characteristic line β becomes the characteristic line β ′ and the characteristic line γ becomes the characteristic line γ ′, which is easily disturbed. As a result, as shown in region G in FIG. 5 (F), β ′ exceeds γ ′, that is, the valve inertial force exceeds the slinging load of the valve spring 5, which causes the jumping of the valve 4. is there.
It is generally said that the jumping of the valve 4 is likely to occur in the state shown in FIG. 5D, that is, in the region between the start of lift and the maximum lift.

(Operation of Embodiment) In this embodiment, the camshaft 1 is rotationally driven by the crankshaft, as in the conventional case. Then, when the cam 17 rotates in accordance with the rotational driving of the cam shaft 1, the pressing surface 30 of the valve lifter 3 is pressed and lifted by the cam surface 170, whereby the valve 4 operates in the valve opening direction and the combustion chamber of the internal combustion engine. Port is opened. Then, as the lift amount of the cam 17 decreases, the valve spring 5 closes the valve 4. This valve opening and closing are repeated.

Now, in the region where the internal combustion engine rotates at high speed,
As described above, the centrifugal force acting on the ball 27a of the speed response mechanism 27 is increased, and the centrifugal force is increased by the cone spring 27b.
The movable shaft 2 automatically moves in the direction of the arrow X2 by overcoming the urging force of. Therefore, as shown in FIG. 1, the permanent magnet 22 automatically faces the intermediate plate 18. In this state,
As shown in FIG. 2, the magnetic flux from the magnetic poles of the permanent magnet 22 passes through the holding plate portion 19 of the cam 17 and reaches the valve lifter 3, whereby a loop-shaped magnetic path M3 is formed. Magnetic path M3
Connects the cam surface 170 of the cam 17 and the pressing surface 30 of the valve lifter 3. Therefore, when the cam 17 rotates, the cam surface 170 magnetically attracts the pressing surface 30 of the valve lifter 3.

On the other hand, when the rotational speed of the internal combustion engine is reduced, the rotational speed of the camshaft 1 is reduced, the centrifugal force acting on the ball 27a is reduced, and the centrifugal force is lost by the urging force of the cone spring 27b. As shown in FIG. 7, the sphere 27a moves in the eccentric direction, whereby the movable shaft 2 is returned in the direction of the arrow X1 and the permanent magnet 22 is retracted from the intermediate plate 18 by a dimension L5. In this state, the magnetic force of the permanent magnet 22 hardly reaches the pressing surface 30 of the valve lifter 3.

(Effects of Embodiment) As described above, in this embodiment, in the region where the internal combustion engine rotates at high speed, the permanent magnet 22 automatically faces the intermediate plate 18 as shown in FIG. The magnet 22 forms a magnetic path M3 that connects the cam surface 170 of the cam 17 and the pressing surface 30 of the valve lifter 3.
Therefore, the cam surface 170 of the cam 17 easily magnetically attracts the pressing surface 30 of the valve lifter 3, and the operability of the cam surface 170 and the pressing surface 30 when the cam 17 rotates is secured. As a result, the cam surface 170 in the high-speed rotation region is
The followability of the valve lifter 3 with respect to is increased. Therefore, it is advantageous to prevent abnormal behavior such as jumping of the valve 4 in the high speed rotation region.

Therefore, in this embodiment, the cam surface 1 of the cam 17 is
In designing the profile of the cam 70, it is not necessary to consider jumping, or even if it is considered, the ratio thereof can be reduced, so that there is an advantage that the degree of freedom in designing the profile of the cam surface 170 is increased and the cam 17 is designed. The area coefficient is improved. Therefore, the charging efficiency of the combustion chamber is improved, which is advantageous for increasing the output, the cam 17 can be made to have a small operating angle, the so-called valve overlap can be made small, and the stability in the idle rotation region can be obtained. To be

As described above, in this embodiment, abnormal behavior such as jumping of the valve 4 in the high speed rotation region can be prevented without excessively increasing the biasing force of the valve spring 5, so that the spring constant is small and the biasing force is small. Weak valve spring 5 can be used. Therefore, the advantage that the frictional resistance between the cam surface 170 and the pressing surface 30 can be reduced in the low speed rotation range is obtained, the driving of the cam 17 is facilitated, and it is also advantageous in improving the fuel consumption in the idle rotation range and the mode running range. is there.

Further, in this embodiment, the intermediate plate 18 made of a non-magnetic material is sandwiched by the sandwiching plate portions 19 made of a ferromagnetic material,
Although the cam 17 is configured, the diameter of the cam 17 is equal to that of the cam shaft 1.
Since the diameter is larger than the diameter, the joining area is secured, which is also advantageous in securing the joining strength between the intermediate board 18 and the sandwiching board portion 19. Further, in this embodiment, since the intermediate plate 18 made of a non-magnetic material is provided inside the cam 17, the magnetic flux generated from the permanent magnet 22 is moved far in the radial direction of the cam shaft 1, that is, the pressing surface of the valve lifter 3. You can fly to the 30 side. As a result, a magnetic path M3 (schematic diagram) that connects the cam surface 170 of the cam 17 and the pressing surface 30 of the valve lifter 3 is easily formed, and the cam surface 170 has an advantage of easily magnetically attracting the pressing surface 30 of the valve lifter 3.

Further, as described above, the valve 4 is used in the internal combustion engine.
It is generally said that the jumping is likely to occur in the region between the start of the lift and the maximum lift. In this regard, in this embodiment, as can be understood from FIG. 6, in the region between the start of lift and the maximum lift, firstly, the valve lifter 3 is
Since the effective radius r1 of the cam surface 170 facing the pressing surface 30 is small, the length of the magnetic path portion connecting the magnet 22 and the pressing surface 30 of the valve lifter 3 is shortened to L1, and the magnetic resistance is reduced. . Second, the pressing surface 30 of the valve lifter 3
Since the lateral side surface 170a of the cam surface 170 contacting with the cam surface 170 has a gentle arc, that is, a small curvature, the contact area or the approach area between the cam surface 170 and the pressing surface 30 increases, and in this sense, the magnetic resistance decreases. Therefore, the cam surface 17
An attraction force of 0 for magnetically attracting the pressing surface 30 is secured. Therefore, the followability of the valve lifter 3 with respect to the cam 17 is ensured, which is advantageous in suppressing jumping of the valve 4.

In other words, this embodiment has an advantage that the magnetic attraction force is increased in the state shown in FIG. 6 where jumping is likely to occur. On the other hand, as shown in FIG. 7, at the time of maximum lift in which the nose portion 171 of the cam surface 170 presses the pressing surface 30, the nose portion 171 has a sharper curvature than the other cam surface 170, and therefore the surface pressure is Increased, so cam 1
During rotation of 7, the troubles such as increase in frictional resistance between the cam surface 170 and the pressing surface 30 and occurrence of seizure are likely to occur. In this regard, in this embodiment, the nose portion 17 of the cam 17 is
At the time of maximum lift in which 1 presses the pressing surface 30, firstly,
Since the nose part 171 is sharp and has a large curvature, the nose part 1
The contact area between 71 and the pressing surface 30 is small, and the magnetic resistance is large. Secondly, as shown in FIG. 7, the length of the magnetic path portion connecting the magnet 22 and the pressing surface 30 becomes as long as L2, and the magnetic resistance also becomes large in this sense. Therefore, the cam surface 170
The magnetic force for magnetically attracting the pressing surface 30 is weakened, which is advantageous in suppressing frictional resistance, seizure, and the like.

In other words, in the present embodiment, the fact that the effective radius and the curvature of the cam surface 170 of the cam 17 change instantaneously is utilized for adjusting the magnetic attraction force. By the way, in a region where the internal combustion engine rotates at a low speed, since the inertial force acting on the valve 4 is small, magnetic attraction is basically not required. In this respect, in the present embodiment, in the region where the internal combustion engine rotates at a low speed, the movable shaft 2 is automatically moved in the direction of the arrow X1 by the speed response mechanism 27, and as shown in FIG. Permanent magnet 2 to move away from board 18
The influence of the magnetic force from 2 can be cut off.

Further, in the present embodiment, there are a mode in which magnetic attraction is performed by the permanent magnet 22 and a mode in which magnetic attraction is not performed.
Since it can be automatically switched by the simple speed response mechanism 27, a complicated mechanism is not required and it is also advantageous in suppressing the price. In addition, in this embodiment, the oil passage 2 in the camshaft body 12 is
Since the oil of the internal combustion engine is supplied to 5, the movement of the movable shaft 2 can be smoothed. Further, it is also advantageous for cooling the permanent magnet 22 of the movable shaft 2, and it is also possible to use the permanent magnet 22 made of a material having a low Curie point that shifts from a ferromagnetic body to a paramagnetic body, and the permanent magnet 22 is made of oil. Since the passage 25 is covered with oil, it is also advantageous in preventing rust on the permanent magnet 22. Therefore, there is an advantage that the degree of freedom in selecting the material of the permanent magnet 22 is increased.

(Other Example) Another example of the present invention is shown in FIGS.
Shown in. In the example shown in FIG. 8, a female screw portion 3h is formed on the valve lifter 3, a male screw portion 4h is formed on an end portion of the valve stem 40 of the valve 4, and the both are screwed to connect the valve lifter 3 and the valve 4. is doing. By doing this, the valve 4
Since it reliably follows the movement of the valve lifter 3, it is more advantageous in preventing abnormal behavior such as jumping of the valve 4 and can contribute to the improvement of the jump-proof rotation speed.

In order to secure heat resistance, the valve, especially the exhaust valve, is generally made of a high alloy material, and therefore, it may be a non-magnetic material like austenitic heat resistant steel. In this point, in the example shown in FIG. 9, the upper portion 40a of the valve stem 40 of the valve 4 is made of ferromagnetic steel.
Lower part 40 of valve head 41 and valve stem 40 of
b is formed of a non-magnetic material or a material that is not easily magnetized, and the upper portion 40a and the lower portion 40b are joined by a joining means such as friction welding or laser welding. In this example, since the upper portion 40a is made of ferromagnetic steel, it is easily magnetically attracted by the valve lifter 3, so that the valve 4 can easily follow the valve lifter 3. Further, as shown in FIG. 9, if the valve lifter 3 is provided with the non-magnetic body portion 3i, it becomes easy to form a magnetic path M4 (schematic diagram) through which the magnetic flux of the magnet 22 reaches the valve 4, and the followability of the valve 4 is ensured. It is even more advantageous.

Further, in the example shown in FIG. 10, the lateral side surface 1 of the cam surface 170 is in a state before the maximum lift, that is, in a state where abnormal behavior such as jumping of the valve 4 is likely to occur.
An inclined surface 30e along the arc of 70a is formed on the pressing surface 30 of the valve lifter 3. Therefore, the contact area between the cam surface 170 and the pressing surface 30 increases, and the cam surface 170 and the pressing surface 3
The magnetic resistance in the boundary area with 0 decreases, and as a result,
The advantage that the attraction force for the cam surface 170 to magnetically attract the pressing surface 30 increases is obtained. The degree of inclination of the inclined surface 30e is appropriately selected in consideration of ensuring the contact area and smooth operability of the cam 17.

As described above, the nose portion 17 of the cam 17 is used.
At the time of maximum lift in which 1 presses the pressing surface 30 of the valve lifter 3, in order to reduce friction resistance, seizure, etc., the cam surface 1
70 wants to weaken the attraction force for magnetically attracting the pressing surface 30. In this regard, in the example shown in FIG. 11, the nose portion 171
A ferromagnetic material portion 19 forming a part of the holding plate portion 19 is provided in the vicinity.
Since i is formed, a magnetic path through which the magnetic flux passes through the ferromagnetic body portion 19i is formed, which is advantageous in weakening the attraction force by which the cam surface 170 magnetically attracts the pressing surface 30.

The examples shown in FIGS. 12 (A) to 12 (D) suppress the rattling of the permanent magnet 22 in the radial direction. That is, in the example shown in FIG. 12 (A), a plurality of protrusions 12k facing the centripetal direction are formed on the inner peripheral surface of the cam shaft body 12 of the cam shaft 1. In the example shown in FIG. 12B, a rolling element 12p functioning as a bearing is interposed between the cam shaft body 12 of the cam shaft 1 and the permanent magnet 22. FIG. 12 (C)
In the example shown in (1), the inner diameter of the cam shaft main body 12 of the cam shaft 1 and the outer diameter of the permanent magnet 22 are substantially the same, and the permanent magnet 22 is formed with an oil passage 25 for cooling the same. In the example shown in FIG. 12D, a ring-shaped bearing 12r having an oil passage 25 is interposed between the cam shaft body 12 of the cam shaft 1 and the permanent magnet 22. The protrusion 12k, the rolling element 12p, and the bearing 12r may be formed of a ferromagnetic material and used as a magnetic path portion having a small magnetic resistance.

In the example shown in FIG. 13A, the cam 17
A through hole 18t or a non-through hole 18s is formed in the intermediate plate 18 made of a non-magnetic material, which is a component of FIG. Hole 1
It is filled in 8s to improve the bondability of both. See also FIG.
In the example shown in (B), the locking protrusions 18n and 18m are formed on the intermediate plate 18 made of a non-magnetic material which is a constituent element of the cam 17, and the holding plate part 19 is locked to the locking protrusions 18n and 18m. This enhances the bondability of both.

In the embodiment shown in FIG. 1 described above, the movable shaft 2 is moved by the speed response mechanism 27 in the directions of the arrows X1 and X2. An electromagnet that moves the movable shaft 2 in the directions of the arrows X1 and X2 by magnetic attraction or magnetic repulsion may be provided.
Alternatively, an oil chamber that generates a hydraulic pressure that moves the movable shaft 2 in the directions of the arrows X1 and X2 may be provided.

In the example shown in FIG. 1 described above, the valve lifter 3 is entirely made of a ferromagnetic material. However, the invention is not limited to this, and only a portion required for magnetic attraction is made of a ferromagnetic material.
The other part may be formed of an aluminum-based alloy in order to reduce the inertial mass. Also, in the embodiment shown in FIG.
Is applied to a multi-valve direct-acting valve operating mechanism that directly hits the valve lifter 3 with, but is not limited to this.
The driven body is not limited to the valve lifter 3, and the driven body may be a rocker arm. In this case, the driven body may be a rocker arm. Followability is secured.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be appropriately modified and implemented without departing from the scope of the invention.

[0038]

According to the valve operating mechanism of the internal combustion engine of the present invention, since the magnetic path connecting the cam surface of the cam and the pressing surface of the driven body is formed by the magnet, the cam magnetically attracts the driven body. And the operability of the cam surface and the pressing surface is secured,
As a result, the followability of the follower with respect to the cam is enhanced. Therefore, it is advantageous to prevent abnormal behavior such as valve jumping.

In addition, when a non-magnetic material is embedded in the cam, the magnetic flux generated from the magnet is easily blown to the pressing surface of the driven body, whereby the cam surface of the cam and the pressing surface of the driven body are separated. A magnetic path to be connected is easily formed, and the followability of the follower with respect to the cam is further secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a valve mechanism in a high speed region.

FIG. 2 is an enlarged cross-sectional view of the main part shown in FIG.

FIG. 3 is a cross-sectional view of a main part of a valve mechanism in a low speed region.

FIG. 4 is a configuration diagram showing the principle of the embodiment.

5A is a diagram showing a valve lift characteristic of an internal combustion engine, FIGS. 5B to 5E are configuration diagrams showing an operating mode of a cam, and FIG. 5F is an internal combustion engine considering dynamic effects. It is a figure which shows the valve lift characteristic of an engine.

FIG. 6 is a configuration view showing a state in which a jumping is likely to occur and an operating mode of a cam.

FIG. 7 is a configuration diagram showing a maximum lift in which the nose portion of the cam is pressing the pressing surface of the valve lifter.

FIG. 8 is a cross-sectional view of a main part according to another example.

FIG. 9 is a cross-sectional view of a main part according to another example.

FIG. 10 is a configuration diagram of a main part according to another example in which the contact area between the cam surface of the cam and the pressing surface of the valve lifter is increased.

FIG. 11 is a cross-sectional view of a main part according to another example in which a ferromagnetic part is provided on the nose part of the cam.

12A to 12D are cross-sectional views according to each example showing a supporting form of a permanent magnet.

13 (A) and (B) are cross-sectional views of a main part according to another example showing a joining mode of the intermediate plate part and the sandwiching plate part.

[Explanation of symbols]

In the figure, 1 is a cam shaft, 11 is a hollow chamber, 17 is a cam, 170
Is a cam surface, 18 is an intermediate plate, 19 is a holding plate, 2 is a movable shaft, 22 is a permanent magnet, 25 is an oil passage, 27 is a speed response mechanism, 3 is a valve lifter (follower), 30 is a pressing face, 4 Indicates a valve, and 5 indicates a valve spring.

Claims (1)

[Claims] 1. A cam shaft rotatably provided in an internal combustion engine having a combustion chamber and a valve for opening and closing a port of the combustion chamber, and a cam held by the cam shaft and rotating with the rotation of the cam shaft. A magnetic path that connects the cam surface of the cam and the pressing surface of the driven body, and a driven body that has a pressing surface that is pressed by the cam surface of the cam and that follows the rotation of the cam to operate the valve. And a magnet that enhances the followability of the driven body with respect to the cam, and a valve mechanism for an internal combustion engine.