JPH11173118A - Variable valve taming mechanism of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable timing mechanism of an internal combustion engine to prevent the damage of the function of an energizing means when a cam shaft is rotated based on a crankshaft, in a variable valve timing for an internal combustion engine having an energizing means to energize relative rotation of a cam shaft with the crankshaft. SOLUTION: An arc spring 11 energizes relative rotation of an internal rotor 3 with a sprocket 2. The end part 11b, having the effective number of windings, of the arc spring 11 is arranged on the outside diameter side. Thus, when the arc spring 11 is contracted, bending toward the outside diameter side of the intermediate part 11c of the arc spring 11 is suppressed. As a result, contact of the intermediate part 11c with the wall surface on the outside diameter side of a lead angle chamber 7a is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing mechanism provided in an internal combustion engine for changing at least one of an intake valve and an exhaust valve.

[0002]

2. Description of the Related Art Conventionally, various variable valve timing mechanisms (hereinafter referred to as VVTs) for changing valve timings of intake valves and exhaust valves in accordance with the operation state of an engine have been proposed. As VVT, for example,
The thing disclosed in 133633 gazette etc. is known.

FIG. 6 shows an example of a VVT for an exhaust valve using a spring, including the device described in the above-mentioned publication. The VVT 50 includes a sprocket 5 connected to a crankshaft (not shown) via a timing belt.
The valve timing is changed by relatively rotating the internal rotor 52 connected to the exhaust camshaft (not shown). Sprocket 51
A plurality of protruding portions 51a are formed on the inner surface thereof, and an oil groove 51b is formed between each protruding portion 51a. The internal rotor 52 includes vanes 52a arranged in the oil grooves 51b. Each oil groove 51b is defined by the vane 52a, and an advance chamber 53 and a retard chamber 54 are formed on both sides of the vane 52a.

When the vane 52a reaches the maximum advance position where the volume of the advance chamber 53 is maximized, that is, the volume of the retard chamber 54 is minimized, the rotational phase of the exhaust camshaft with respect to the crankshaft, that is, valve timing. Is the most advanced position (hereinafter referred to as the most advanced valve timing). Conversely, when the vane 52a is at the most retarded position where the volume of the advance chamber 53 is minimized, that is, the volume of the retard chamber 54 is maximized, the valve timing is set to the most retarded position (hereinafter referred to as the most retarded position). Angular valve timing).

[0005] The valve timing of the VVT 50 is changed by oil pressure. More specifically, by causing a difference between the oil pressure in the advance chamber 53 and the oil pressure in the retard chamber 54,
Move the vane 52a toward the lower oil pressure,
The internal rotor 52 is rotated with respect to the sprocket 51.

A spring 55 is provided in each of the advance chambers 53. The spring 55 is disposed in each of the advance chambers 53 in a state in which each of the advance chambers 53 is formed in a fan shape in cross section, and is bent in an arc shape. The spring (hereinafter, referred to as an arc spring) 55 is provided with the vane 52.
a urges the vane 52a in a direction in which a becomes the most advanced position.

A lock pin 5 is provided on one of the vanes 52a.
6 are accommodated. The lock pin 56 is connected to the vane 52a.
Is in the most advanced position, and when the oil pressure in the advance chamber 53 is low, the vane 52a engages with the sprocket 51 side until the oil pressure in the advance chamber 53 reaches a predetermined pressure. At the most advanced position.

In the VVT 50 configured as described above, when the engine is started, the oil pressure in both chambers 53 and 54 is low, so that the vane 52a is at the most advanced position by the urging force of the arc spring 55, and the lock pin 56 Is held at the position. That is, when the engine is started, the relative rotation between the sprocket 51 and the internal rotor 52 is regulated at the most advanced position. Therefore, the valve timing on the exhaust side when the engine is started is the most advanced valve timing. As a result, for example, it is possible to reduce the amount of overlap between the intake and exhaust valves when starting the engine.

On the other hand, when the oil pressure increases with the operation of the engine, the engagement between the lock pin 56 and the sprocket 51 is released, and the internal rotor 52 can rotate with respect to the sprocket 51. Therefore, when a predetermined difference is generated between the oil pressure in the advance chamber 53 and the oil pressure in the retard chamber 54, the internal rotor 52 rotates with respect to the sprocket 51. As a result, the valve timing can be changed to an optimal timing according to the operating state of the engine.

[0010]

By the way, the coil-shaped spring of the arc spring 55 is compressed from a normal expanded state as shown in FIG. 7A, as shown in FIG. 7B. When it is in a contracted state, it is 180 ° opposite from the end 60a of the effective number of turns of the spring 60 (in the figure, the direction of arrow A)
The middle part of the spring 60 is bent. Note that the effective number of turns is a part obtained by removing the number of end turns from the total number of turns of the coil, and the number of end turns is a portion having no function of a spring in which a coil end portion is flattened in order to improve the sitting of the coil. It is.

Therefore, in the VVT 50, the vanes 52
When a moves in the direction of the most retarded position, the intermediate portion 55a of the arc spring 55 may bend in the outer peripheral direction, and the intermediate portion 55a may come into contact with the oil groove 51b of the sprocket 51.

[0012] This causes deterioration in responsiveness when changing the valve timing. In addition, it causes the arc spring 55 to be rubbed and worn. In addition, the spring load (load) of the spring 55 changes between when the valve timing is changed to the advance side and when the valve timing is changed to the retard side, which causes a deterioration in controllability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a variable valve of an internal combustion engine provided with an urging means for urging a relative rotation of a camshaft with respect to a crankshaft in one direction. It is an object of the present invention to provide a variable valve timing mechanism for an internal combustion engine in which the function of the urging means is not impaired when the camshaft rotates with respect to the crankshaft.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a first rotating body having at least one concave section having a sector shape in a cross section, and a first pressure body having a concave section having a first pressure. A second rotating body having a vane partitioned into a chamber and a second pressure chamber, the second rotating body being rotatably combined with the first rotating body; and a relative rotation of the second rotating body with respect to the first rotating body. Biasing means for biasing the movement in one direction, wherein the rotational force of the crankshaft transmitted to one of the first rotating body or the second rotating body is transmitted from the other of the first rotating body or the second rotating body. By transmitting the signal to the camshaft, the valve of the internal combustion engine is driven at a predetermined valve timing.
The vane is moved by varying the pressure in at least one of the pressure chamber and the second pressure chamber,
In a variable valve timing mechanism for an internal combustion engine in which the valve timing is changed by relatively rotating the second rotating body with respect to a rotating body, the urging means may include the first pressure chamber or the second pressure chamber. And an arc spring for urging the relative rotation in one direction by urging the vane against the side surface of the concave portion. The end of the effective number of turns of the arc spring is The gist is that it is arranged on the outer diameter side.

According to a second aspect of the present invention, there is provided a first rotating body having at least one recess therein, and a vane dividing the recess into a first pressure chamber and a second pressure chamber. A second rotating body combined with the first rotating body so as to be relatively rotatable with respect to the body, and an urging means for urging the relative rotation of the second rotating body with respect to the first rotating body in one direction; The valve of the internal combustion engine is driven at a predetermined valve timing by transmitting the torque of the crankshaft transmitted to one of the rotating body and the second rotating body to the camshaft from the other of the first rotating body and the second rotating body. The vane is moved by changing the pressure in at least one of the first pressure chamber and the second pressure chamber, and the second rotating body is relatively rotated with respect to the first rotating body. Change the valve timing In the variable valve timing mechanism for an internal combustion engine, the biasing means is a torsion spring, one end of which is supported by an outer peripheral portion of the first rotating body, and a coil portion of which is provided by the first rotating body. It is arranged at a predetermined interval on the outer peripheral side, the other end is connected to the second rotating body, and the relative rotation is biased in one direction by the torsion force of the coil portion. I have.

(Operation) According to the first aspect of the present invention,
When the second rotating body is rotated in a direction opposite to the direction in which the arc spring is urged, the arc spring is compressed and contracted by the vane. At this time, since the end portion of the effective number of turns of the arc spring is arranged on the outer diameter side of the first rotating body, the middle portion of the arc spring is suppressed from bending toward the outer diameter side. Therefore, the intermediate portion does not contact the outer diameter side wall surface in the first pressure chamber or the second pressure chamber. As a result, when the second rotating body relatively rotates with respect to the first rotating body, the function of the arc spring as the urging means is not impaired.

According to the second aspect of the present invention, the urging means is a torsion spring for urging the relative rotation in one direction by the torsional force of the coil portion, and the coil portion is the first spring. Since the coil portion is arranged at a predetermined interval on the outer peripheral side of the rotating body, it does not come into contact with the first rotating body or the like when the coil portion is twisted. Therefore, the function of the torsion spring as the urging means is not impaired when the second rotating body relatively rotates with respect to the first rotating body.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, the present invention will be described with reference to a variable valve timing mechanism (VV) for an exhaust valve.
The first embodiment embodied in T) will be described with reference to FIGS.

As shown in FIGS. 1 and 2, the VVT 1 has a sprocket 2 and an internal rotor 3. The sprocket 2 is connected to a crankshaft (not shown) via a timing belt. The internal rotor 3 is
It is connected and fixed to an exhaust camshaft 4 for driving an exhaust valve (not shown).

An outer peripheral housing 5 formed in an annular shape is attached to one side surface of the sprocket 2, and a cover 6 serving as a lid is attached to the outer peripheral housing 5. The outer peripheral housing 5 has three protruding portions 5a formed on the inner peripheral surface, and an oil groove 5b is formed between each protruding portion 5a. The inner rotor 3 is held in the outer peripheral housing 5 so as to be relatively rotatable. The inner rotor 3 has a vane 3a formed in each oil groove 5b. Each oil groove 5b is defined by the vane 3a, and an advance chamber 7a and a retard chamber 7b are formed on both sides of the vane 3a. The sprocket 2 rotates clockwise in FIG. 1 based on the rotation of the crankshaft. The advance chamber 7a is a counterclockwise direction of the vane 3a, and the retard chamber 7b is a clock of the vane 3a. Each of them is formed in a substantially fan-shaped cross section on the circumferential direction side.

When the vane 3a is at the most advanced position where the volume of the advance chamber 7a is maximized, that is, the volume of the retard chamber 7b is minimized, the rotational phase of the exhaust camshaft 4 with respect to the crankshaft, ie, the valve The timing is the most advanced position (hereinafter, referred to as the most advanced valve timing). Conversely, when the vane 3a is at the most retarded position where the volume of the advance chamber 7a is the minimum, that is, the volume of the retard chamber 7b is the maximum,
The valve timing is at the most retarded position (hereinafter, referred to as the most retarded valve timing).

A lock pin receiving hole 3b is formed in one of the vanes 3a, and a lock pin 8 is received in the lock pin receiving hole 3b. The lock pin 8 is urged by a spring 9 toward one side of the sprocket 2. On the other hand, on one side surface of the sprocket 2, an engagement hole 2a for engaging with the tip 8a of the lock pin 8 is formed. The engaging hole 2a is formed corresponding to the position of the lock pin 8 when the vane 3a is at the most advanced position, and engages with the lock pin 8 at this position. The lock pin receiving hole 3b
Inside, there is a step formed on the inner surface thereof and a lock pin 8.
A pin pressurizing chamber 10 is formed which is surrounded by the step formed in the above. The pin pressurizing chamber 1 is provided in the vane 3a.
A communication hole 3c is formed to communicate the zero and the advance chamber 7a. When the oil pressure in the advance chamber 7a (the pressurizing chamber 10) increases and the urging force by the pressure exceeds the urging force of the spring 9, the tip 8a of the lock pin 8 and the engaging hole 2a
Is disengaged.

Each of the advance chambers 7a is provided with an arc spring 11 as an urging means. More specifically, as shown in FIG. 3, the arc spring 11 has a coil outer periphery formed in a substantially fan shape corresponding to the advance chamber 7a having a fan-shaped cross section. At both ends of the arc spring 11, there are formed seats 11a having a function of a spring in which a coil wire is obliquely ground in order to improve the seating of the coil and a wire wound ahead of the coil wire is overlapped with the ground portion. Have been. An end portion 11b of the arc spring 11 excluding the seat 11a, that is, an end portion of the effective number of turns (hereinafter, an effective winding end portion) 11b is an outer diameter side of the sprocket 2, that is, an outer diameter side centering on a rotation axis of the inner rotor 3. Are located in One of the seats 11a is supported by a counterbore 3e formed on the side surface of the vane 3a, and the other is a bottom guide 5 formed on the side surface of the protruding portion 5a.
c and the outer peripheral guide 5d. Therefore, the arc spring 11 urges the vane 3a in a direction in which the vane 3a is at the most advanced position.

The sprocket 2 is provided with the advance chamber 7.
A passage 2b communicating with the retardation chamber 7b is formed, a passage 3f communicating with the retard chamber 7b is formed in the internal rotor 3, and the two passages 2b and 3f communicate with control pumps (not shown) through separate paths. .

In the VVT 1 thus configured, since the oil pressure supplied from the control pump at the time of starting the engine is low, the oil pressures in the advance chamber 7a and the retard chamber 7b are both low, and the vane 3a It is in the most advanced position by the urging force. At this time, the lock pin 8 is pushed by the spring 9 so that the engagement hole 2 of the sprocket 2
a, the vane 3a is locked at the most advanced position. That is, when the engine is started, the relative rotation between the sprocket 2 and the internal rotor 3 is reliably restricted at the most advanced position. Therefore, the valve timing at the time of starting the engine is the most advanced valve timing.

On the other hand, when the oil pressure supplied from the control pump increases with the operation of the engine, and the urging force due to the oil pressure in the advance chamber 7 a (the pressurizing chamber 10) exceeds the urging force of the spring 9. Then, the engagement between the lock pin 8 and the engagement hole 2a is released, and the internal rotor 3 can rotate with respect to the sprocket 2. When oil having independent pressures is supplied from the control pump into the advance chamber 7a and the retard chamber 7b by predetermined control, the vane 3a is controlled based on the oil pressure and the urging force of the arc spring 11. Then, the inner rotor 3 rotates with respect to the sprocket 2. Therefore, it is possible to change the valve timing to the optimal timing for the operating state of the engine.

Here, when the oil pressure in the retard chamber 7b is higher than the oil pressure in the advance chamber 7a, and the urging force due to the difference in the oil pressure exceeds the urging force of the arc spring 11, the vane 3a The arc spring 11 is compressed and moves in the direction of the most retarded position. At this time, since the effective winding end 11b of the arc spring 11 to be compressed is disposed on the outer diameter side of the sprocket 2, the middle portion 11c of the arc spring 11 is suppressed from bending outward.
As a result, the intermediate portion 11c of the arc spring 11 does not come into contact with the oil groove 5b of the outer peripheral housing 5.

Next, the characteristic action and effect of the present embodiment will be described below. According to the present embodiment, the intermediate portion 11c of the arc spring 11 for urging the vane 3a in the direction of the most advanced position.
Does not come into contact with the oil groove 5b of the outer peripheral housing 5, so that the responsiveness when changing the valve timing due to the arc spring 11 is not impaired.

Further, the arc spring 11 is prevented from being rubbed and worn. Further, when the valve timing is changed to the advance side and when the valve timing is changed to the retard side, the arc spring 11 is changed.
Is prevented from changing, and the controllability is improved.

According to this embodiment, the valve timing of the exhaust valve at the time of starting the engine always becomes the most advanced valve timing. From this, for example, this VVT1
Can always fix the valve timing of the intake and exhaust valves at the time of engine start to the valve timing with a small overlap amount. Therefore, the VVT 1 can prevent the blowback to the intake side which occurs at the time of starting the engine, and can improve the startability of the engine.

(Second Embodiment) A second embodiment in which the present invention is embodied in a variable valve timing mechanism (VVT) for an exhaust valve will be described below with reference to FIGS. The VVT 21 according to the second embodiment is different from the VVT 1 according to the first embodiment mainly in the urging means for setting the relative rotation between the sprocket and the internal rotor to the most advanced position. Therefore, description of other similar components will be partially omitted.

As shown in FIGS. 4 and 5, the VVT 21 includes a sprocket 22 and an internal rotor 233. The sprocket 22 is connected to a crankshaft (not shown) via a timing belt. The internal rotor 23 is connected and fixed to an exhaust camshaft 24 for driving an exhaust valve (not shown).

An outer peripheral housing 25 formed in an annular shape is attached to one side surface of the sprocket 22, and a cover 26 serving as a lid is attached to the outer peripheral housing 25.
7 attached. The outer peripheral housing 25 has four protruding portions 25a formed on the inner peripheral surface, and an oil groove 25b is formed between each protruding portion 25a. The internal rotor 23 is held in the outer peripheral housing 25 so as to be relatively rotatable. The inner rotor 23 is provided with vanes 23a arranged in the oil grooves 25b. Each oil groove 25b is defined by the vane 23a, and an advance chamber 28a and a retard chamber 28b are formed on both sides of the vane 23a. The sprocket 22 rotates clockwise in FIG. 4 based on the rotation of the crankshaft. The advance chamber 28a is a counterclockwise side of the vane 23a, and the retard chamber 28b is a vane 23.
It is formed on the clockwise side of a.

When the vane 23a is at the most advanced position where the volume of the advance chamber 28a is maximized, that is, the volume of the retard chamber 28b is minimized, the valve timing becomes the most advanced valve timing. Conversely, when the vane 23a is at the most retarded position where the volume of the advance chamber 28a is the minimum, that is, the volume of the retard chamber 28b is the maximum, the valve timing is the most retarded valve timing.

A lock pin receiving hole 23b is formed in one of the vanes 23a as in the first embodiment.
The lock pin 29 is accommodated in the lock pin accommodation hole 23b. The lock pin 29 is urged by a spring 30 toward one side of the sprocket 22. On the other hand, an engaging hole (not shown) is formed on one side surface of the sprocket 22 similarly to the first embodiment, and the engaging hole is provided when the vane 3a is at the most advanced position. Engage with. Further, the engagement between the lock pin 29 and the engagement hole increases the oil pressure in the advance chamber 28a as in the first embodiment, and the urging force by the pressure reduces the urging force of the spring 30. It will be released when it exceeds.

On the outer side of the cover 26, there is provided a support arm 32 which is non-rotatably connected to the internal rotor 23 by connecting bolts 31. That is, a slide hole (not shown) is formed in the center of the cover 26, and the internal rotor 23 and the support arm 32 are connected via the slide hole. Accordingly, the support arm 32 rotates with the internal rotor 23 relative to the sprocket 22, the outer peripheral housing 25, and the cover 26. The support arm 32 includes
An arm portion 32a extending to the outer peripheral side is formed.
A support recess 32b is formed at the tip of 2a. or,
On the outer peripheral surface of the outer peripheral housing 25, a plurality of support protrusions 25c extending in the outer peripheral direction are formed.

On the outer peripheral surface side of the outer peripheral housing 25,
A torsion spring 33 supported by the support recess 32b and the support protrusion 25c is provided. More specifically, the torsion spring 33 is supported by one end 33a of the torsion spring 33 being sandwiched and supported in the support recess 32b of the support arm 33.
b turns around the outer peripheral surface side of the outer peripheral housing 25 several times, and the other end is hung on the support protrusion 25c. The torsion spring 33 urges the support arm 32 in a direction in which the vane 23a that rotates together with the support arm 32 is at the most advanced position. When the vane 23a moves from the most advanced position to the most retarded position, the torsion spring 33 has a desired interval such that the inner peripheral surface of the coil portion 33b does not contact the outer peripheral surface of the outer peripheral housing 25. Are located.

The advance chamber 28a and the retard chamber 28b
Are connected to a control pump (not shown) through separate paths similarly to the first embodiment. In the VVT 21 configured as described above, since the oil pressure supplied from the control pump at the time of starting the engine is low, the oil pressures in the advance chamber 28a and the retard chamber 28b are both low, and the vane 32a is actuated by the urging force of the torsion spring 33. It is the most advanced position.
At this time, since the lock pin 29 is engaged with the engagement hole of the sprocket 22 by the urging force of the spring 30 in the same manner as in the first embodiment, the vane 23a is locked at the most advanced position. I have. That is, when the engine is started, the relative rotation between the sprocket 22 and the internal rotor 23 is reliably restricted at the most advanced position. Therefore, the valve timing at the time of starting the engine is the most advanced valve timing.

On the other hand, when the oil pressure supplied from the control pump increases with the operation of the engine and the urging force due to the oil pressure in the advance chamber 28a exceeds the urging force of the spring 30, the first embodiment is performed. As in the embodiment described above, the engagement between the lock pin 29 and the engagement hole is released, and the internal rotor 23 can rotate with respect to the sprocket 22. Then, the advance pump 28a and the retard chamber 2
When oils having independent pressures are supplied to the inside of the sprocket 8b, the vane 23a moves based on the oil pressure and the urging force of the torsion spring 33, and the internal rotor 23 rotates with respect to the sprocket 22. Therefore, it is possible to change the valve timing to the optimal timing for the operating state of the engine.

Here, when the oil pressure in the retard chamber 28b is higher than the oil pressure in the advance chamber 28a, and the biasing force due to the difference in the oil pressure exceeds the biasing force of the torsion spring 33, the vane 23a The torsion spring 33 is moved in the direction of the most retarded position while being twisted. At this time, the torsion spring 3
In No. 3, since the coil portion 33b has a desired interval with respect to the outer peripheral surface of the outer peripheral housing 25, it does not come into contact with the outer peripheral housing 25 or the like when being twisted.

Next, the characteristic actions and effects of the present embodiment will be described below. According to the present embodiment, the torsion spring 33 that urges the vane 23a in the direction of the most advanced position is the outer peripheral housing 2
Since there is no contact with the fifth and the like, the responsiveness when changing the valve timing due to the torsion spring 33 is not impaired.

According to the present embodiment, since the torsion spring 33 for urging the vane 23a in the most advanced position is provided on the outer peripheral surface side of the outer peripheral housing 25, the arc spring is provided in the advanced chamber. Compared to sprocket 22
, The relative rotatable angle (phase variable width) of the internal rotor 23 with respect to the angle.

· Torsional spring 33 as biasing means
Since is not exposed to oil, the durability is better as compared with a configuration in which an arc spring as an urging means is provided in the advance chamber. Further, since the torsion spring 33 as the urging means has a lower spring constant than the arc spring as the urging means, even if the phase angle of the internal rotor 23 with respect to the sprocket 22 is displaced, the change in the spring load is small. . Therefore, responsiveness and controllability are better as compared with the configuration in which the arc spring as the urging means is provided.

According to this embodiment, the valve timing of the exhaust valve at the time of starting the engine always becomes the most advanced valve timing. From this, for example, this VVT2
1 can always fix the valve timing of the intake / exhaust valve at the time of engine start to a valve timing with a small overlap amount. Therefore, this VVT 21
Thus, it is possible to prevent the air from returning to the intake side at the time of starting the engine, thereby improving the startability of the engine.

The above embodiment may be modified and implemented as follows. In the first and second embodiments, VVTs 1 and 21 are used.
Is VVT for an exhaust valve. On the other hand, VVT
1, 21 may be VVT for the intake valve. In this case, the urging means (arc spring, torsion spring) 1
It is necessary to make a change such that the direction of urging by the first and the third 33 is reversed. Even in this case, the same effect as in the above embodiment can be obtained.

In the first and second embodiments, oils having independent pressures are supplied into the advance chambers 7a and 28a and the retard chambers 7b and 28b to move the vanes 3a and 23a. Alternatively, the vanes 3a and 23a may be moved by oil pressure supplied to the retard chambers 7b and 28b without supplying oil to the advance chambers 7a and 28a. still,
In this case, it is necessary to change the communication hole 3c communicating the pin pressurizing chamber 10 and the advance chamber 7a to a communication hole communicating the pin pressurizing chamber 10 and the retard chamber 7b. . Even in this case, the same effect as in the above embodiment can be obtained.

In the first and second embodiments, the oil is supplied into the advance chambers 7a, 28a and the retard chambers 7b, 28b to move the vanes 3a, 23a. For example, it may be moved by another method.

In the first and second embodiments, the lock pins 8 and 29 are provided for reliably restricting the relative rotation of the internal rotors 3 and 23 with respect to the sprockets 2 and 22 at a predetermined position. The lock pin 8,
29 may not be provided.

In the first and second embodiments, the lock pins 8, 29 and the sprockets 2, 22 are engaged when the vanes 3a, 23a are at the most advanced positions. That is, when the engine is started, the valve timing of the exhaust valve is set to the most advanced valve timing. On the other hand, the positions where the lock pins 8 and 29 and the sprockets 2 and 22 are engaged may be appropriately changed. By doing so, the valve timing of the exhaust valve at the time of starting the engine can be changed to a desired valve timing.

In the first embodiment, three oil grooves 5b are formed, but the number of oil grooves 5b may be any number. Further, the number of vanes 3a may be appropriately changed.

In the second embodiment, four oil grooves 25b are formed.
May be any number. Further, the number of vanes 23a may be appropriately changed.

[0052]

As described in detail above, according to the present invention,
In a variable valve timing mechanism of an internal combustion engine provided with an urging means for urging the relative rotation of the camshaft with respect to the crankshaft in one direction, the function of the urging means when the camshaft rotates with respect to the crankshaft is provided. It has an excellent effect of not being damaged.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a variable valve timing mechanism according to a first embodiment.

FIG. 2 is a sectional view taken along the line BB of FIG. 1;

FIG. 3 is an explanatory diagram for explaining an arc spring.

FIG. 4 is a sectional view of a main part of a variable valve timing mechanism according to a second embodiment.

FIG. 5 is a perspective view of a variable valve timing mechanism according to a second embodiment.

FIG. 6 is an explanatory diagram for explaining a conventional variable valve timing mechanism.

FIG. 7A is an explanatory view showing a spring in a normal state. (B) Explanatory drawing for demonstrating the bending of a spring when compressed.

[Explanation of symbols]

2,22 ... sprocket as the first rotating body, 3,23
... An internal rotor as a second rotating body, 4, 24 a cam shaft, 11 an arc spring as a biasing means, 33
... torsion springs as biasing means, 3a, 23a ... vanes, 5b, 25b ... oil grooves as recesses, 7a, 7b
... Advance chamber and retard chamber as the first pressure chamber and the second pressure chamber, 11b ... End of effective winding number, 33b ... Coil part.

Claims (2)

[Claims] A first rotating body having at least one concave section having a sector-shaped cross section therein; and a vane dividing the concave section into a first pressure chamber and a second pressure chamber. A second rotating body combined so as to be relatively rotatable with the first rotating body, and biasing means for biasing the relative rotation of the second rotating body with respect to the first rotating body in one direction. By transmitting the torque of the crankshaft transmitted to one of the second rotating bodies to the camshaft from the other of the first rotating body or the second rotating body, the valve of the internal combustion engine is driven at a predetermined valve timing, The vane is moved by changing a pressure in at least one of the first pressure chamber and the second pressure chamber, and the second rotating body is relatively rotated with respect to the first rotating body, so that the valve timing is adjusted. To change In the variable valve timing mechanism of the internal combustion engine, the urging means is provided in the first pressure chamber or the second pressure chamber, and urges the vane against the side surface of the recess to cause relative rotation in one direction. A variable valve timing mechanism for an internal combustion engine, wherein an end of an effective number of turns of the arc spring is disposed on an outer diameter side of the first rotating body. 2. A first rotating body having at least one recess therein, and a vane dividing the recess into a first pressure chamber and a second pressure chamber, wherein the vane is relatively rotated with respect to the first rotating body. A second rotator combined as possible, and an urging means for urging a relative rotation of the second rotator with respect to the first rotator in one direction, wherein the first rotator or the second rotator is provided. By transmitting the rotational force of the crankshaft transmitted to one of the first rotating body or the second rotating body to the camshaft, the valve of the internal combustion engine is driven at a predetermined valve timing, and the first pressure The vane is moved by changing the pressure in at least one of the chamber and the second pressure chamber, and the valve timing is changed by rotating the second rotating body relative to the first rotating body. Internal combustion engine In the variable valve timing mechanism, the urging means is a torsion spring, one end of which is supported by an outer peripheral portion of the first rotating body, and a coil portion of which is disposed at a predetermined interval on the outer peripheral side of the first rotating body. A variable valve timing of the internal combustion engine, wherein the other end is connected to the second rotating body, and the relative rotation is urged in one direction by the torsional force of the coil portion. mechanism.