JP2947183B2 - Variable valve timing mechanism for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable mechanism provided in an internal combustion engine for varying at least one of an intake valve and an exhaust valve. For more information,
The present invention relates to a variable valve timing mechanism driven by using fluid pressure.

[0002]

2. Description of the Related Art Conventionally, various devices have been proposed which can change the valve timing of an intake valve or an exhaust valve of an internal combustion engine. JP-A-5-106412 discloses that
A variable valve timing mechanism is disclosed as an example.

As shown in FIG. 7, the apparatus disclosed in the above publication has a vane 90 provided at the tip of a cam shaft 89, and two lobes 91 and 92 formed on the outer periphery of the vane 90.
, A sprocket 93 rotatable relative to the vane 90, and seals 94, 95 provided at the tips of the lobes 91, 92. Branch holes 98 and 99 for supplying hydraulic pressure communicate with the recesses 96 and 97 that house the lobes 91 and 92, respectively. The recesses 96 and 97 communicate with each other via slots 100.

The rotation of the sprocket 93 causes the vane 90 to rotate integrally with the sprocket 93.
Here, the hydraulic pressure is selectively supplied to the branch holes 98, 99, so that the hydraulic pressure acts on the lobes 91, 92 disposed in the recesses 96, 97, respectively. As a result, the vane 90 rotates relative to the sprocket 93. Accordingly, the rotation phase of the camshaft 89 integrated with the vane 90 is changed, and the camshaft 89
The timing of the valve driven by is adjusted.

The seals 94 and 95 press the inner peripheral surface 101 of the sprocket 93 with a predetermined force, and
The oil tightness inside 97 is improved. Here, each recess 96,
In order to further improve the oil tightness between the
It is conceivable to provide a seal 102 shown by a chain line on the inner peripheral surface 101 of the sprocket 93 in contact with the sprocket 93. This seal 1
02, the inner peripheral surface 101 of the sprocket 93 and the vane 9
The sealing performance between the outer peripheral surface 103 and the outer peripheral surface 103 is improved. Accordingly, oil leakage from the recess 96 to the recess 97 or oil leakage from the recess 97 to the recess 96 is suppressed.

[0006]

In the above variable mechanism, oil tightness between the recesses 96 and 97 is improved by providing the seals 94, 95 and 102. However, on the other hand, the inner peripheral surface 101 of the sprocket 93 and the vane 90
The sliding resistance between the outer peripheral surface 103 and the seals 94, 95, 102 is increased. Further, the camshaft 8
Rotation of the vane 90 together with 9 generates centrifugal force on each of the seals 94, 95, 102. For this reason, the seals 94, 95, and 102 receive an outward force. Here, the centrifugal force acts in a direction to reduce the sliding resistance between the seal 102 and the outer peripheral surface 103. However, the centrifugal force is
It works in a direction to further increase the sliding resistance between 4,95 and the inner peripheral surface 101. As a result, the operation responsiveness of the variable mechanism may decrease as the sliding resistance increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide two pressure chambers for receiving a supply of fluid, and to change the valve timing by adjusting the fluid pressure in each pressure chamber. In the variable valve timing mechanism for an internal combustion engine, the sealing performance of each pressure chamber is ensured, and the operation response of the variable mechanism is improved.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, an invention according to claim 1 is a variable valve timing mechanism for varying at least one of an intake valve and an exhaust valve of an internal combustion engine. A first rotating body and a second rotating body are provided so as to be relatively rotatable around the same camshaft, the first rotating body is fixed on the camshaft, and the rotating body is provided on the outer periphery thereof. First extending towards
The second rotating body is provided so as to include the first rotating body, and the second rotating body is provided on the inner circumferential surface of the second rotating body so as to extend inward. And two projections, which are in contact with the outer peripheral surface of the first rotating body, and a first projection defined between the two rotating bodies by the first projection in the rotation direction of the two rotating bodies. A pressure chamber and a second pressure chamber are formed, and the valve timing is changed by selectively supplying a fluid pressure to the first and second pressure chambers and rotating both rotating bodies relative to each other. In the variable valve timing mechanism of the engine, the first projection is provided with first sealing means for sealing between the first projection and the inner peripheral surface of the second rotating body, and the first sealing means is provided. A first urging means for urging the second rotating body toward the inner peripheral surface of the second rotating body. The second projection is provided with a second sealing means for sealing between the outer peripheral surface of the rotating body and the second sealing means for urging the second sealing means toward the outer peripheral surface of the first rotating body. Is provided, and the biasing force of the first biasing means is set to be smaller than the biasing force of the second biasing means.

According to the above arrangement, the first and second sealing means receive centrifugal force, respectively, by rotating both the rotating bodies with the rotation of the camshaft. Then, centrifugal force is applied to the first sealing means in the same direction as the urging force toward the inner peripheral surface of the second rotating body by the first urging means. For this reason, the first sealing means includes:
Centrifugal force acts in a direction to increase the sealing performance. A centrifugal force is applied to the second sealing means in a direction opposite to the urging force toward the outer peripheral surface of the first rotating body by the second urging means. For this reason, a centrifugal force acts on the second sealing means in a direction to reduce the sealing performance.

Here, the urging force of the second urging means is set larger than that of the first urging means. Therefore, even if a centrifugal force is applied in the opposite direction to the urging force, the pressing force of the second sealing means against the first rotating body does not become insufficient, and the sealing performance does not become insufficient. On the other hand, since the urging force of the first urging means is set to be smaller than that of the second urging means, even if a centrifugal force is applied to the urging force in the same direction, the first seal is applied. The pressing force of the means against the second rotating body does not become excessive, and the sealing performance is ensured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) An embodiment embodying a variable valve timing mechanism of an internal combustion engine will be described below with reference to the drawings. In this embodiment, in a gasoline engine as an internal combustion engine, a variable valve timing mechanism (hereinafter referred to as “VV
T ". ) Is indicated.

FIG. 2 shows the intake and exhaust camshafts 1.
It is a top view which shows 1,70. In the figure, the left side is the distal side, and the right side is the proximal side. The intake-side and exhaust-side camshafts 11 and 70 are rotatably supported by the cylinder head 14. Both camshafts 11 and 70 have a plurality of cams 75. Below the cam 75, the intake valve 7
7 and an exhaust valve 78 are arranged. The VVT 12 is provided at the tip of the intake camshaft 11. Drive gear 74 provided at the tip of exhaust side camshaft 70
And the driven gear 17 provided at the tip of the intake-side camshaft 11 mesh with each other. A pulley 71 is provided at the base end of the exhaust camshaft 70, and the pulley 71 is connected to a crankshaft (not shown) via a timing belt 72.

When the crankshaft is rotated, its rotational force is transmitted to the pulley 71 via the belt 72, and the exhaust camshaft 70 is rotated. The rotational force of the exhaust camshaft 70 is transmitted to the intake camshaft 11 via the gears 74 and 17, and the camshaft 11 is rotated. The rotation of the camshafts 11 and 70 in this manner causes the intake valve 77 and the exhaust valve 78 to rotate.
Is opened and closed.

FIG. 1 is a sectional view showing a VVT 12 provided at the tip of an intake-side camshaft (hereinafter simply referred to as a “camshaft”) 11. As shown in the figure, the upper end of the cylinder head 14 and the bearing cap 15
Supports the journal 11a of the camshaft 11 rotatably. The camshaft 11 has an enlarged diameter portion 1 at its tip.
1b. A bolt 22 is provided on the tip surface of the camshaft 11.
The impeller 19 as a first rotating body fixed by
The shaft 11 is prevented from rotating by a knock pin (not shown), and rotates integrally with the shaft 11. The impeller 19 has a plurality of blades 24 as first projections on its outer peripheral surface 23a.

A driven gear 17 provided so as to cover the enlarged diameter portion 11b of the camshaft 11 and to be rotatable relative to the camshaft 11 has a plurality of external teeth 17a on its outer periphery.
Having. The side plate 18, the housing 16 as a second rotating body, and the cover 20, which are sequentially attached to the enlarged diameter portion 11 b and the distal end surface of the driven gear 17, are fixed to the driven gear 17 by bolts 21, and are integrated with the driven gear 17. To rotate. The cover 20 covers the front end surfaces of the housing 16 and the impeller 19. The housing 16 is provided so as to include the impeller 19, and has a plurality of ridges 25 as second projections on an inner peripheral surface 26a thereof.

The impeller 19 has an oil groove 36 formed on the tip surface. The groove 36 communicates the elongated hole 37 formed in the cover 20 with the through hole 32. The oil groove 36 and the elongated hole 37 have a function of discharging air or oil located on the distal end side of the lock pin 33 inside the through hole 32 to the outside.

Each blade 24 has a groove 27 at its tip (outer peripheral surface 24a). Similarly, each ridge 25 has a respective groove 81 formed at the tip thereof. The length in the radial direction of both grooves 27 and 81 is the same. As shown in FIGS. 1 and 4, in the groove 27 of each blade 24, a first seal plate 28 as a first sealing means is arranged. Between the first seal plate 28 and the inner wall of the groove 27, first leaf springs 29 as first urging means are arranged. The leaf spring 29 includes a seal plate 28.
To the inner peripheral surface 26a of the housing 16.
The seal plate 28 is provided on the inner peripheral surface 26 a of the housing 16.
Abut.

Similarly, in the groove 81 of each ridge 25, a second seal plate 82 as a second sealing means is arranged. Between the seal plate 82 and the inner wall of the groove 81, second leaf springs 83 as second urging means are arranged. The leaf spring 83 urges the seal plate 82 toward the outer peripheral surface 23 a of the impeller 19. The seal plate 82 is provided on the outer peripheral surface 2 of the impeller 19.
Contact 3a.

FIG. 3 shows a cross section taken along the line 3-3 in FIG. 1 (FIG. 1 shows a cross section taken along the line 1-1 in FIG. 3), and FIG. Shown. As shown in FIG. 3, the impeller 19 includes a cylindrical boss 23 located at the center thereof, four blades 24 formed at intervals of approximately 90 ° around the boss 23, and each blade 24. And a first recess 79 formed therebetween.

The housing 16 has an inner peripheral surface
It has four ridges 25 projecting toward the center and arranged at equal intervals from each other. The second recesses 26 formed between the ridges 25 respectively accommodate the blades 24.
The outer peripheral surface 24 a of each blade 24 is in contact with the inner peripheral surface 26 a of each second concave portion 26, and the inner peripheral surface 25 a of each ridge 25 is
3 is in contact with the outer peripheral surface 23a. By being partitioned by each blade 24, first and second hydraulic chambers 30 and 31 as first and second pressure chambers are formed on both sides of each blade 24 in the rotation direction, respectively.

Each blade 24 includes a cover 20, a second recess 2
6. The space surrounded by the boss 23 and the side plate 18 is divided into two hydraulic chambers 30, 31. The valve timing is advanced to the first hydraulic chamber 30 located on the side opposite to the direction of rotation of the driven gear 17 (indicated by the arrow in FIG. 2) (hereinafter, this direction is defined as “retarded direction”). When the oil is supplied. When the valve timing is delayed, oil is supplied to the second hydraulic chamber 31 located on the same side as the rotation direction (hereinafter, this direction is defined as “advance angle direction”).

Here, when the engine is stopped, the urging force (initial load) of the first leaf spring 29 is applied to the second leaf spring 8.
3 is set smaller than the urging force (initial load).
That is, the spring coefficient of the first leaf spring 29 is
Is set to be smaller than the spring coefficient. Second recess 2
6 and the sealing property between the inner circumferential face 25a of the ridge 25 and the outer circumferential face 23a of the first recess 79, respectively. And it improves as the urging force of the second leaf springs 29 and 83 increases. On the other hand, at the time of relative rotation of the blade 24, the sliding resistance between the inner peripheral surface 26a of the second recess 26 and the outer peripheral surface 24a of the blade 24, and the inner peripheral surface 25a of the ridge 25 and the first The sliding resistance between the first and second leaf springs 29 and 83 increases as the urging force of the first and second leaf springs 29 and 83 increases.

As shown in FIG. 1, one of the blades 24 has a through hole 32 extending along the axial direction of the camshaft 11. The lock pin 33 movably provided in the through hole 32 has an accommodation hole 33a therein. A spring 35 provided in the accommodation hole 33a urges the pin 33 toward a locking hole 34 formed in the side plate 18. When the lock pin 33 is engaged with the locking hole 34, the position of the impeller 19 with respect to the housing 16 is such that the side surface of the blade 24 on the first hydraulic chamber 30 side is It is fixed at a position slightly separated from the part 25. Thereby, the relative rotation between the impeller 19 and the side plate 18 is restricted, and the camshaft 11 and the driven gear 17 rotate integrally.

Next, oil passages P1 and P2 for supplying and discharging oil to each of the first hydraulic chambers 30 and each of the second hydraulic chambers 31.
Will be described. The cylinder head 14 has a first oil passage 38 and a second oil passage 39 formed therein.
Each of the oil passages 38 and 39 is connected to a first port 55 and a second port 56 of the OCV 40 which will be described later. OCV
40 communicates with an oil pan 43 via an oil filter 41, a pump 13, and an oil strainer.

The first oil passage 38 is formed in the camshaft 11 through an oil groove 44 formed in the entire circumference of the journal 11a and an oil hole 45 formed in the journal 11a. It leads to 46. The distal end of the oil passage 46 opens into an annular space 47 defined by the inner peripheral portion of the base end of the boss 23, the bolt 21, and the side plate 18. Inside the boss 23, a part of each blade 24 and each protruding ridge 25, four radially formed oil holes 48 communicate the annular space 47 with each of the first hydraulic chambers 30, and the annular space 47 The oil supplied to the inside is supplied to each first hydraulic chamber 30.

The second oil passage 39 is provided between the upper end of the cylinder head 14 and the oil groove 5 formed in the bearing cap 15.
Leads to zero. The oil hole 53, the oil passage 63, and the oil hole 52 formed in the camshaft 11 are formed in an annular shape formed between the oil groove 50, the base side surface of the side plate 18, and the front side surface of the enlarged diameter portion 11b. It communicates with the oil space 51. The side plate 18
As shown in FIG. 3, each of the protrusions 25 has four oil holes 52 opened near the side surface. Each oil hole 52 communicates the oil space 51 with each second hydraulic chamber 31, and supplies the oil in the oil space 51 into the hydraulic chamber 31. The oil space 51 communicates with the locking hole 34 described above, and the oil in the space 51 is supplied into the locking hole 34.

The first oil passage 38, the oil groove 44, the oil hole 45, the oil passage 46, the annular space 47, and each oil hole 48 serve as a first oil for supplying oil to each first hydraulic chamber 30. The road P1 is configured. Second oil path 39, oil groove 50, oil hole 53, oil space 5
1, the oil passage 63 and each oil hole 52 are provided in each second hydraulic chamber 31
A second oil passage P2 for supplying oil to the oil passage.

When the oil pressure is supplied to the oil passage P1 during the operation of the engine, the oil pressure in the hydraulic chamber 30 increases,
The lock pin 33 comes out of the locking hole 34 by the oil pressure. As a result, the relative rotation between the impeller 19 and the driven gear 17 is allowed. The intake valve 77 is opened and closed at a predetermined valve timing by the rotation of the camshaft 11.

Further, each of the first hydraulic chambers 3 is provided through an oil passage P1.
When the oil is supplied to 0, the oil in each second hydraulic chamber 31 is drained through the oil passage P2. As a result, the hydraulic pressure in each first hydraulic chamber 30 is relatively higher than the hydraulic pressure in each second hydraulic chamber 31, so that a rotational force in the “advance direction” acts on each blade 24. I do. This rotational force causes the impeller 19 to rotate relatively to the driven gear 17 in the “advanced direction”, and the rotational phase of the camshaft 11 changes to the driven gear 17.
, The valve timing of the intake valve 77 is advanced from the current state. The state in which the impeller 19 is relatively rotated in the “advance angle direction” with respect to the driven gear 17 and the respective blades 24 abut against the respective ridges 25 is a state in which the valve timing is the most advanced.

On the other hand, when the oil is supplied to each second hydraulic chamber 31 through the oil passage P2, the oil in each first hydraulic chamber 30 is drained through the oil passage P1. As a result, the hydraulic pressure in each second hydraulic chamber 31 is relatively increased compared to the hydraulic pressure in each first hydraulic chamber 30, and the rotational force in the “retarded direction” is applied to each blade 24. Works. The rotational force causes the impeller 19 to rotate relatively in the “retarded direction” with respect to the driven gear 17, and the rotational phase of the camshaft 11 is retarded relative to the rotational phase of the driven gear 17. As a result, the valve timing of the intake valve 77 is delayed from the current state. The impeller 19 is the driven gear 1
The state in which the blades 24 are relatively rotated in the “retarded direction” with respect to 7 and the respective blades 24 are in contact with the respective ridges 25 is the state in which the valve timing is most delayed.

Through the oil passages P1 and P2, each hydraulic chamber 30,
By supplying the same hydraulic pressure to the impeller 31,
And the driven gear 17 stops rotating. This allows
The valve timing of the intake valve 77 is maintained at the current timing.

As described above, by controlling the supply of the oil pressure to the oil passages P1 and P2, the valve timing of the intake valve 77 is set to a predetermined timing between the timing of the most retarded angle and the timing of the most advanced angle. It can be changed continuously (steplessly), and the valve timing can be maintained.

When the supply of the hydraulic pressure to the oil passage P1 is stopped when the engine is stopped, the hydraulic pressure in the locking hole 34 and the hydraulic chamber 30 is reduced. For this reason, the lock pin 3
3 moves in the through hole 32 and engages with the locking hole 34 again. Therefore, until the oil pressure in the hydraulic chamber 30 increases to a predetermined value by the restart of the engine and the supply of the oil pressure to the oil passage P1, the impeller 19 and the side plate 18
Relative rotation is restricted. For this reason, a long time has elapsed since the engine was stopped until the engine was restarted.
Even when the oil in 0 and 31 leaks out, the generation of vibration in the rotation direction of the impeller 19 is suppressed. As a result, generation of abnormal noise caused by collision of each blade 24 and each ridge 25 by the vibration is prevented.

Here, the housing 1 is operated during operation of the engine.
6 is rotated, so that the impeller 19
6 and rotated in synchronism. As the housing 16 and the impeller 19 are rotated with the rotation of the camshaft 11, the first and second seal plates 28 and 82 receive centrifugal force, respectively. Then, a centrifugal force is applied to the first seal plate 28 by the first leaf spring 29 in the same direction as the urging force toward the inner peripheral surface 26 a of the housing 16. For this reason, a centrifugal force acts on the first seal plate 28 in a direction to increase the sealing performance. The second leaf spring 8 is provided on the second seal plate 82.
3, centrifugal force is applied in the opposite direction to the urging force toward the outer peripheral surface 23a of the impeller 19. For this reason, a centrifugal force acts on the second seal plate 82 in a direction to reduce the sealing performance.

Here, the urging force of the second leaf spring 83 is set to be larger than that of the first leaf spring 29.
Therefore, even if a centrifugal force is applied in the opposite direction to the urging force, the pressing force of the second seal plate 82 against the impeller 19 does not become insufficient, and the sealing performance does not become insufficient. On the other hand, since the urging force of the first leaf spring 29 is set to be smaller than that of the second leaf spring 83, even if a centrifugal force is applied to the urging force in the same direction, the first seal is applied. The pressing force of the plate 28 against the housing 16 is not excessive, and the sealing property is ensured.

Therefore, in this embodiment, the biasing forces of the first and second leaf springs 29 and 83 are set in advance in anticipation of the centrifugal force caused by the rotation of the camshaft. Of the VVT1
2 can improve the operation responsiveness.

In this embodiment, during operation of the engine, the first seal plate 28 is urged against the second recess 26 with an appropriate force. Therefore, the blade 2
The abrasion of the first seal plate 28 that occurs during the relative rotation of the fourth seal 4 can be reduced. For this reason, since the abrasion powder of the first seal plate 28 which may be mixed into the oil is reduced, it is possible to suppress a decrease in the operability of the OCV 40 due to the abrasion powder.

In this embodiment, the seal plates 28 and 82 are biased by the first and second leaf springs 29 and 83, respectively. Therefore, for example, even if the seal plate 28 is worn,
Of the same plate 2
The surface pressure between the inner peripheral surface 8 and the inner peripheral surface 26a hardly decreases. As a result, the sealing performance of the seal plate 28 can be maintained for a long period of time, and oil leakage from both hydraulic chambers 30 and 31 can be reliably suppressed. (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and the description of those members will be omitted. Particularly, different points will be mainly described.

As shown in FIG. 7, the VVT of this embodiment is
84 differs from the first embodiment in the radial length of each groove 85 and the spring coefficient of each first leaf spring 86. Specifically, the length L1 of each groove 85 in the radial direction is longer than the length L2 of each groove 81 in the radial direction. Here, the first and second leaf springs 86 and 83 are springs having the same shape and substantially the same spring coefficient. The second leaf spring 83 is contracted from the first leaf spring 86 so that each groove 8
1 is provided.

As described above, the first and second leaf springs 86,
83 are the same springs, but because the amount of contraction of the springs is different, the urging force (initial load) of the first leaf spring 86 is set smaller than the urging force (initial load) of the second leaf spring 83. You. Therefore, the VVT 84 of this embodiment, like the VVT 12 of the first embodiment, rotates the camshaft 11 to rotate the first and second seal plates 28 and 8.
2 receives centrifugal force. A force obtained by adding the urging force of the first leaf spring 86 and the centrifugal force is applied to the first seal plate 28. Since the urging force of the first leaf spring 29 is previously set small in anticipation of the centrifugal force, the force by which the first seal plate 28 urges the inner peripheral surface 26a of the second concave portion 26 is not appropriate. Become.

As a result, the inner peripheral surface 26a of the second concave portion 26
And the outer peripheral surface 24a of the blade 24, the operability of the VVT 84 can be improved without increasing the sliding resistance of the two 26a, 24a.

In this embodiment, since the first and second leaf springs 86 and 83 have the same spring coefficient, the same leaf spring can be used and the productivity can be improved. Note that the present invention can be embodied in another embodiment as follows. In the following another embodiment, the same operation and effect as the above embodiment can be obtained.

(1) In each of the above embodiments, the seal plate 28 is fixed to the second recess 26 by the first leaf spring 29.
Of the inner peripheral surface 26a. On the contrary,
By omitting each leaf spring 29, the configuration can be simplified. In this case, as a material of the seal plate 28, for example, a soft metal such as brass, copper, or aluminum, or a rubber having oil resistance and heat resistance such as nitrile rubber, acrylic rubber, or fluoro rubber is selected. Due to the elastic force, the plate 28
May be urged against the inner peripheral surface 26a of the concave portion 26.

(2) In each of the above embodiments, the first and second seal plates 28 and 82 are urged by the first
And the second leaf springs 29 and 83 were used. On the other hand, other urging means such as a coil spring or rubber may be used to urge the two seal plates 28 and 82. When the leaf spring 29 is changed to rubber, it is desirable that the rubber material has oil resistance and heat resistance such as the above-mentioned nitrile rubber, acrylic rubber, and fluorine rubber.

(3) In the above embodiments, four blades 24 are formed on the impeller 19. On the other hand, a configuration having three or less blades 24 or five or more blades 24 is also possible. (4) In each of the above embodiments, the driven gear 17 may be changed to a sprocket, and the VVT 12 may be changed to a configuration in which a timing chain is mounted on the sprocket.

(5) In each of the above embodiments, the exhaust camshaft 70 is driven by the crankshaft, and the rotation phase of the intake camshaft 11 can be changed. On the other hand, the pulley 7 provided on the exhaust side camshaft 70
1 may be provided at the base end side of the intake side camshaft 11, and the pulley 71 may be connected to the crankshaft via the belt 72. According to this configuration, the intake side camshaft 11 is driven by the crankshaft, and the gear 1
The rotation phase of the exhaust-side camshaft 70 is changed via the switches 7 and 74.

(6) In each of the above embodiments, the intake valve 7
The valve timing of 7 was changed. On the other hand, the VVT 12 may be provided on the exhaust camshaft 70 to change the valve timing of the exhaust valve 78. Further, the VVT 12 is provided on both the intake side camshaft 11 and the exhaust side camshaft 70, and the intake valve 7 is provided.
The valve timing of both the exhaust valve 7 and the exhaust valve 78 may be changed.

Further, technical ideas other than the claims that can be grasped from the above embodiment will be described below together with their effects. (A) In the variable valve timing mechanism for an internal combustion engine according to claim 1, the first and second biasing means are respectively composed of first and second elastic members, and the elastic coefficient of the two elastic members or the two A variable valve timing mechanism for an internal combustion engine, wherein an elastic force of the first elastic member is set smaller than an elastic force of the second elastic member by adjusting an initial deformation amount of the elastic member.

According to this configuration, the elastic force of both elastic members can be easily adjusted by changing the elastic coefficient or the initial deformation amount of both elastic members. (B) In the variable valve timing mechanism for an internal combustion engine according to the above (A), the first and second elastic members have substantially the same elastic coefficient, and the first and second elastic members are respectively The first elastic member is accommodated in the first and second grooves, and the length of the first groove is longer than the length of the second groove, so that the initial deformation amount of the first elastic member is reduced by the second initial value. A variable valve timing mechanism for an internal combustion engine, wherein the variable valve timing mechanism is set smaller than a deformation amount.

According to this configuration, even if the first and second elastic members having the same elastic modulus are used, the length of the groove for accommodating the first and second elastic members is changed. The elastic force of the first elastic member can be set smaller than the elastic force of the second elastic member. As described above, since the same elastic member can be used, the productivity of the variable valve timing mechanism is improved.

[0051]

According to the first aspect of the present invention, the first urging means urges the first sealing means toward the inner peripheral surface of the second rotating body, and the second urging means. The means urges the second sealing means toward the outer peripheral surface of the first rotating body, and sets the urging force of the first urging means to be smaller than the urging force of the second urging means.

Therefore, even if a centrifugal force is applied in the opposite direction to the urging force, the pressing force of the second sealing means against the first rotating body does not become insufficient, and the sealing performance does not become insufficient. Absent. On the other hand, since the urging force of the first urging means is set to be smaller than that of the second urging means, even if a centrifugal force is applied to the urging force in the same direction, the first seal is applied. The pressing force of the means against the second rotating body does not become excessive, and the sealing performance is ensured.
Therefore, it is possible to ensure the sealing performance of each pressure chamber and to improve the operation response of the variable mechanism.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a VVT.

FIG. 2 is a plan view showing a camshaft and a VVT.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 5;

FIG. 5 is an enlarged sectional view showing a blade, a seal plate, and the like.

FIG. 6 is a plan view showing a blade, a seal plate, and the like in another embodiment.

FIG. 7 is a sectional view showing a conventional VVT.

[Explanation of symbols]

11 ... intake camshaft as camshaft, 16
.., A housing as a second rotating body, 19, an impeller as a first rotating body, 23 a, an outer peripheral surface, 24, a blade as a first projection, 25, a ridge as a second projection, 26
a ... inner peripheral surface, 27, 81, 85 ... groove, 28, 82 ... seal plate as sealing means, 29, 83, 86 ... leaf spring as urging means, 30, 31 ... hydraulic chamber as pressure chamber, 77 ... intake valve, 78 ... exhaust valve.

Claims (1)

(57) [Claims] 1. A variable valve timing mechanism for varying valve timing of at least one of an intake valve and an exhaust valve of an internal combustion engine, wherein a first rotating body and a second rotating body are arranged around the same camshaft. The first rotator is provided on the camshaft, and is provided so as to be relatively rotatable. The rotator has a first protrusion extending outward on an outer periphery thereof, and the protrusion is the second rotator. Abuts against the inner surface of
The second rotator is provided so as to include the first rotator, and has a second protrusion extending inward on an inner periphery thereof.
The projection is in contact with the outer peripheral surface of the first rotating body,
A first pressure chamber and a second pressure chamber defined by the first protrusion in a rotation direction of the two rotators are formed between the two rotators, and the first and second pressure chambers are formed. A variable valve timing mechanism for an internal combustion engine, wherein the valve timing is changed by selectively supplying a fluid pressure to the rotating body and rotating the two rotating bodies relative to each other. First sealing means is provided on the first projection for sealing between the inner peripheral surface of the rotating body and the first projection, and the first sealing means is moved toward the inner peripheral surface of the second rotating body. A first urging means for urging is provided, and a second sealing means is provided on the second projection to seal between the second projection and an outer peripheral surface of the first rotating body. Is provided, and the second sealing means is moved toward the outer peripheral surface of the first rotating body. An internal combustion engine provided with second biasing means for biasing, wherein the biasing force of the first biasing means is set smaller than the biasing force of the second biasing means; Variable valve timing mechanism.