JP5022327B2 - Variable valve timing mechanism for internal combustion engine - Google Patents

Description

The present invention relates to a variable valve timing mechanism that varies the opening / closing timing of one or both of an intake valve and an exhaust valve in accordance with the operating state of an internal combustion engine.

Conventionally, as a variable valve timing mechanism (hereinafter referred to as a mechanism), a camshaft having a housing having a plurality of shoes and transmitting the rotational force of the crankshaft and a plurality of vanes relatively rotating between the shoes. And a vane rotor that transmits rotational force to the advancing and retarding chambers separated by the shoe and the vane, and the oil pressure causes the camshaft phase relative to the crankshaft to be advanced or A hydraulic drive type that changes to the retard side is known.

Further, when the internal combustion engine shifts from the operating state to the stopped state, the vane rotor may not be positioned at a predetermined initial position suitable for (re) starting of the internal combustion engine due to the influence of the rotational reaction force acting on the camshaft. In order to prevent this, an urging means for urging the vane in one direction with respect to the housing is provided, and this urging force holds the vane rotor at a predetermined initial position to stably operate the mechanism. Are known. For example, in the mechanism described in Patent Document 1, a spring (coil spring) is installed as a biasing means between a shoe and a vane that form an advance chamber in the exhaust side mechanism, and the vane rotor is always attached to the advance side. By energizing, it is possible to hold at the initial position (most advanced angle position) when the engine is stopped.
Japanese Patent No. 3964207

However, in the mechanism described in Patent Document 1, since the deformation amount of the urging means (spring compression amount) is not regulated, the spring may be plastically deformed and the urging force may change. The present invention has been made paying attention to the above-mentioned problem, and an object of the present invention is to provide a variable valve timing mechanism capable of preventing a change in the urging force of the urging means while stably operating the mechanism by the urging means. Is to provide.

In order to achieve the above object, the variable valve timing mechanism of the present invention makes the relative rotation when the housing and the vane rotor rotate relative to each other in the direction opposite to the direction in which the vane is biased by the biasing means. A restricting shoe and a vane are provided, and an urging means is provided for each of the shoe and the vane except for the shoe and the vane for restricting relative rotation.

Therefore, a change in the urging force of the urging means can be prevented and the mechanism can be operated more stably.

Hereinafter, the best mode for realizing the variable valve timing mechanism of the present invention will be described with reference to the drawings.

(Configuration of variable valve timing mechanism)
FIG. 1 shows the configuration of a valve timing control device (hereinafter referred to as VTC) applied to the exhaust side of an internal combustion engine (hereinafter referred to as engine). The VTC is a hydraulic drive type, and supplies hydraulic oil for the variable valve timing mechanism 1 (hereinafter referred to as mechanism 1) that continuously changes the rotational phase of the camshaft 3 with respect to the crankshaft using hydraulic pressure. Or a hydraulic supply / discharge mechanism 2 that discharges or discharges, and control means (controller CU) that variably controls the valve timing by controlling the operation of the hydraulic supply / discharge mechanism 2.

In FIG. 1, a partial cross section passing through the rotation axis O (see FIG. 2) of the mechanism 1 is shown. Hereinafter, for convenience of explanation, the X axis is provided in the axial direction of the camshaft 3, and the side on which the camshaft 3 is installed with respect to the mechanism 1 is defined as the positive direction. 2A and 3 are cross-sectional views taken along line AA in FIG. The mechanism 1 in FIG. 1 corresponds to the B-O-B cross section in FIG. FIG. 4 is a partial perspective view of the mechanism 1 (with the vane rotor 4 assembled to the housing main body 102) with the front plate 101 and the like removed as viewed from the X-axis negative direction side.

The mechanism 1 is a hydraulic actuator having a housing 10 and a vane rotor 4, and is installed at the end of the exhaust camshaft 3. The torque of the crankshaft is transmitted to the housing 10. The vane rotor 4 is provided so as to be relatively rotatable with respect to the housing 10, and a rotational force is transmitted from the housing 10 via the hydraulic oil, and the rotational force is transmitted to the camshaft 3.

The housing 10 includes a front plate 101, a main body 102, and a rear plate 103. The main body 102 is a cylindrical member that opens at both ends in the X-axis direction. The front plate 101 closes the opening end of the main body 102 on the X axis negative direction side. The rear plate 103 closes the opening end of the main body 102 on the X axis positive direction side. The rear plate 103 is formed with female screws for fastening four small-diameter bolts b1 to b4. The front plate 101, the main body 102, and the rear plate 103 are negatively connected to the X-axis by the small-diameter bolts b1 to b4. It is tightened and fixed integrally from the direction side.

A sprocket 104 is integrally provided adjacent to the rear plate 103 on the X axis positive direction side. The sprocket 104 is a drive rotating body (timing sprocket) that is driven to rotate by the crankshaft of the engine via a wound timing chain, and teeth that engage with the timing chain are formed on the outer periphery (see FIG. 2). The sprocket 104 rotates in the clockwise direction in FIG.

On the inner peripheral surface of the main body 102, first to fourth shoes 11 to 14, which are four partition walls, are protruded toward the inner diameter direction (rotating axis O) at substantially equal intervals in the circumferential direction. . The first to fourth shoes 11, 12, 13, and 14 are arranged in this order in the clockwise direction of FIG. Each shoe 11-14 is formed to extend in the X-axis direction, and a cross section in a direction perpendicular to the X-axis is provided in a substantially trapezoidal shape. Both end surfaces in the X-axis direction of the shoes 11 to 14 are fixedly fixed to the front plate 101 and the rear plate 103.

When viewed from the X-axis direction, the widths of the second and third shoes 12 and 13 in the direction around the rotation axis O (hereinafter referred to as the circumferential direction) are set to be approximately the same. The circumferential width of the first shoe 11 is slightly larger than the circumferential width of the second and third shoes 12 and 13. The circumferential width of the fourth shoe 14 is slightly smaller than the circumferential width of the second and third shoes 12 and 13.

The shoes 11 to 14 are provided at predetermined angular positions in the circumferential direction of the main body 102 so as to balance the weight of the entire housing 10 in the circumferential direction. The circumferential widths of the gap between the first shoe 11 and the second shoe 12, the gap between the second shoe 12 and the third shoe 13, and the gap between the third shoe 13 and the fourth shoe 14 are substantially the same. The size is provided. The circumferential width of the gap between the fourth shoe 14 and the first shoe 11 is slightly larger than the gap between the other shoes.

A bolt insertion hole 110 through which the bolt b1 is inserted is formed in the X-axis direction at substantially the center of the trapezoidal cross section of the first shoe 11. Similarly, bolt insertion holes 120, 130, and 140 are formed in the second to fourth shoes 12 to 14, respectively.

Inner peripheral surfaces 111, 121, 131, 141 on the inner diameter side (rotary axis O side) of the first to fourth shoes 11-14 are formed in a concave arc shape along the outer peripheral surface of the rotor 40 of the vane rotor 4 when viewed from the X-axis direction. ing. A groove 112 is formed in the surface 111 along the X-axis direction. Inside the groove 112, a seal member 113 that is in fluid-tight sliding contact with the outer peripheral surface of the rotor 40 and a seal spring (plate spring) that presses the seal member 113 toward the outer peripheral surface of the rotor 40 are fitted and held. Yes. Similarly, seal members 123, 133, and 143 are provided on the other inner peripheral surfaces 121, 131, and 141, respectively.

A bearing hole 105 is formed through substantially the center of the front plate 101 as viewed from the X-axis direction, and four bolt holes through which bolts b1 to b4 are inserted are formed around the bearing hole 105. . Further, when viewed from the X-axis direction, a bearing hole 106 having substantially the same diameter as the bearing hole 105 is formed through substantially the center of the rear plate 103 and the sprocket 104, and bolts b1 to b4 are provided around the bearing hole 106. Four female screw holes for screwing are formed.

The vane rotor 4 is a vane member integrally formed of a sintered alloy material, and is rotatably accommodated in the housing 10. The vane rotor 4 is a driven rotating body that is rotatable relative to the sprocket 104 (housing 10), and rotates integrally with the camshaft 3 in the clockwise direction of FIG. The vane rotor 4 includes a rotor 40 that is a rotating shaft portion and first to fourth vanes 41, 42, 43, and 44 that are four blades.

The rotor 40 has a main body shaft portion 400, a first extension shaft portion 401, and a second extension shaft portion 402 coaxially, and is coaxially connected to the camshaft 3 by the cam bolt 31 to be the X axis of the camshaft 3. It is integrally fixed to the end 30 on the negative direction side. The first extension shaft portion 401 is formed by extending the main body shaft portion 400 in the X axis negative direction side, and the second extension shaft portion 402 is formed by extending the main body shaft portion 400 in the X axis positive direction side. When viewed from the X-axis direction, the outer periphery of the main body shaft portion 400 and the first and second extension shaft portions 401 and 402 coincide.

The first extension shaft portion 401 is rotatably supported by the bearing hole 105 of the front plate 101, and the second extension shaft portion 402 is rotatably supported by the rear plate 103 and the bearing hole 106 of the sprocket 104. The length of the main body shaft portion 400 in the X-axis direction is substantially equal to the length of the main body portion 102 of the housing 10 in the X-axis direction. The length of the second extension shaft portion 402 in the X-axis direction is substantially equal to the length of the bearing hole 106 in the X-axis direction.

The first extension shaft portion 401 and the main body shaft portion 400 are formed with fitting holes 403 coaxially with the rotor 40 from the X-axis negative direction side. The second extension shaft portion 402 has a fitting hole 404 formed coaxially with the rotor 40 from the X axis positive direction side. Further, a bolt hole 405 through which the cam bolt 31 is inserted is formed coaxially with the rotor 40 across both the main body shaft portion 400 and the second extension shaft portion 402, and the fitting hole 403 and the fitting hole 404 are communicated with each other. ing. The diameter of the fitting hole 403 that accommodates the flange (head portion) of the cam bolt 31 is slightly larger than the diameter of the fitting hole 404, and the diameter of the bolt hole 405 that accommodates the shaft of the cam bolt 31 is larger than the diameter of the fitting hole 404. small.

On the outer peripheral surface of the main body shaft portion 400, first to fourth vanes 41 to 44 project radially from the outer diameter direction (the direction away from the rotation axis O) at substantially equal intervals in the circumferential direction. . The first to fourth vanes 41 to 44 are arranged in this order in the clockwise direction of FIG. Each of the vanes 41 to 44 is formed to extend in the X-axis direction, and the cross-sectional shape in the direction perpendicular to the X-axis is formed in a substantially trapezoidal shape in which the circumferential width increases toward the outer diameter direction.

The lengths of the vanes 41 to 44 in the X-axis direction are substantially the same as the length of the main body shaft portion 400 in the X-axis direction. In a state where the vane rotor 4 is installed in the housing 10, the X-axis negative direction surface of each vane 41 to 44 faces the X-axis positive direction surface of the front plate 101 with a very small gap. is doing. Further, the surfaces on the X axis positive direction side of the vanes 41 to 44 are opposed to the surfaces on the X axis negative direction side of the rear plate 103 with a very small gap.

The widths of the second to fourth vanes 42 to 44 in the circumferential direction of the main body shaft portion 400 are provided with substantially the same size. The first vane 41 is provided with a lock mechanism 5. The circumferential width of the first vane 41 is formed wider than the second to fourth vanes 42 to 44.

The vanes 41 to 44 are provided at predetermined angular positions in the circumferential direction of the vane rotor 4. The gap between the first vane 41 and the second vane 42, the gap between the second vane 42 and the third vane 43, and the gap between the third vane 43 and the fourth vane 44 are substantially the same in the circumferential direction. Is provided. The gap between the fourth vane 44 and the first vane 41 is slightly narrower than the gap between the other vanes (by the width of the first vane 41).

The second vane 42 and the fourth vane 44 are provided at substantially symmetrical positions with the rotation axis O in between. The 3rd vane 43 is provided in the position rotated about 90 degree | times with respect to the 2nd vane 42 (and 4th vane 44). The first vane 41 faces the third vane 43 across the rotation axis O, and is provided at a position slightly rotated counterclockwise so as to move away from the second vane 42 and approach the fourth vane 44. .

With the vane rotor 4 installed in the housing 10, the first vane 41 is between the fourth shoe 14 and the first shoe 11, the second vane 42 is between the first shoe 11 and the second shoe 12, and the third vane. 43 is disposed between the second shoe 12 and the third shoe 13, and the fourth vane 44 is disposed in a gap between the third shoe 13 and the fourth shoe 14.

The outer peripheral surfaces 411, 421, 431, and 441 of the vanes 41 to 44 on the rotor outer diameter side (the side away from the rotation axis O) are formed in an arc shape along the inner peripheral surface of the main body 102 of the housing 10 when viewed from the X-axis direction. Yes. A groove 412 is formed in the outer peripheral surface 411 of the first vane 41 along the X-axis direction. Inside the groove 412, there are fitted a seal member 413 that is in fluid-tight sliding contact with the inner peripheral surface of the main body 102 and a seal spring (plate spring LS) that presses the seal member 413 toward the inner peripheral surface. Is retained. Similarly, seal members 423 to 443 are provided on the outer peripheral surfaces 421 to 441 of the second to fourth vanes 42 to 44, respectively.

Four oil chambers are formed between the adjacent shoes 11 and 12 and the vane rotor 4 (rotor 40), and are made fluid-tight by a seal member 113 and the like. The hydraulic oil supplied from the oil pump P is introduced into these oil chambers, and rotation is transmitted between the vane rotor 4 and the housing 10 via the hydraulic oil. These oil chambers are separated into an advance chamber A and a retard chamber R by vanes 41 and the like.

Specifically, the X-axis positive direction surface of the front plate 101, the X-axis negative direction surface of the rear plate 103, both side surfaces in the circumferential direction of the vanes 41 to 44, and the shoes 11-14. Four sets of hydraulic working chambers, that is, four advance chambers A1, A2, A3, A4 and four retard chambers R1, R2, R3, R4 are separated from each other in the circumferential direction. Yes. For example, as shown in FIG. 2, a first advance chamber A <b> 1 is defined between a counterclockwise surface 414 of the first vane 41 and a clockwise surface 145 of the fourth shoe 14. Yes. In addition, a first retardation chamber R1 is defined between a surface 415 on the clockwise direction side of the first vane 41 and a surface 114 on the counterclockwise direction side of the first shoe 11.

Similarly, the second advance chamber A2 is provided between the second vane 42 and the first shoe 11, the second retard chamber R2 is provided between the second vane 42 and the second shoe 12, and the third vane 43 and the second shoe 12. The third advance chamber A3 between the shoe 12 and the third retard chamber R3 between the third vane 43 and the third shoe 13, and the fourth advance angle between the fourth vane 44 and the third shoe 13. A fourth retardation chamber R4 is defined between the chamber A4, the fourth vane 44, and the fourth shoe 14, respectively.

The camshaft 3 is rotatably supported by a top end portion of a cylinder head of the internal combustion engine via a bearing. A cam is provided on the outer peripheral surface of the camshaft 3 at a position corresponding to the position of the exhaust valve. When the camshaft 3 rotates, the cam opens and closes the exhaust valve via a valve lifter and the like.

An insertion portion 301 is inserted into the fitting hole 404 of the vane rotor 4 (second extension shaft portion 402) and fitted into the end 30 on the X axis negative direction side of the camshaft 3; A flange 302 is formed as a locking portion that restricts the movement of the insertion portion 301 in the negative direction of the X axis. A screw hole 303 is formed in the end portion 30 from the X axis negative direction side. With the insertion portion 301 fitted in the fitting hole 404, the cam bolt 31 is inserted into the bolt hole 405 from the X negative direction side, and the tip of the cam bolt 31 is screwed into the screw hole 303, so that the camshaft 3 The end 30 is fastened and fixed integrally with the vane rotor 4.

The predetermined advance chambers A2 to A4 are provided with urging means 6 for urging the vane rotor 4 (vane) clockwise with respect to the housing 10 (shoe). The urging means 6 has three spring units, that is, first to third spring units 61 to 63. Of the four advance chambers A1 to A4 separated by the shoes 11 to 14 in the counterclockwise direction and the vanes 41 to 44 in the clockwise direction, the three advance chambers A2 separated by the vanes 42 to 44 are included. Each spring unit 61-63 is provided in -A4.

That is, the first spring unit 61 is between the first shoe 11 and the second vane 42 (second advance chamber A2), and the second spring unit 62 is between the second shoe 12 and the third vane 43 (first The third spring unit 63 is housed in the third advance chamber A3) and between the third shoe 13 and the fourth vane 44 (fourth advance chamber A4). The urging means 6 (spring unit) is not provided between the fourth shoe 14 and the first vane 41 (first advance chamber A1).

The first spring unit 61 has one coil spring 610 and holding portions 611 and 612 that are spring retainers provided at both ends thereof. FIG. 2B is an enlarged cross-sectional view of the holding portion 611 in FIG. An engaging portion 613 protruding in a cylindrical shape is formed on one side surface of the holding portion 611, and one end of a coil spring 610 is fitted to the outer periphery of the engaging portion 613. The holding unit 612 is also provided in the same manner as the holding unit 611. Similar to the first spring unit 61, the second spring unit 62 has a coil spring 620 and holding parts 621 and 622, and the third spring unit 63 has a coil spring 630 and holding parts 631 and 632. The urging forces of the coil springs 610 to 630 are substantially the same. The diameters of the coil springs 610 to 630 occupy about 85% of the width in the radial direction (of the housing 10) of the second to fourth advance chambers A2 to A4, respectively.

FIG. 4 shows a state in which the coil spring 630 and the holding portions 631 and 632 (not shown) of the third spring unit 63 are removed. As shown in FIG. 4, a groove 136 for supporting the holding portion 631 is provided on the surface 135 of the third shoe 13 on the clockwise direction side. The groove 136 occupies most of the surface 135 and is formed in a concave shape when viewed from the X-axis direction. The width of the groove 136 in the radial direction (of the housing 10) is substantially the same as the diameter of the holding portion 631, and the groove 136 restricts the movement of the holding portion 631 in the radial direction (of the housing 10). In addition, a guide portion 137 with which the outer periphery of the coil spring 630 can be slidably contacted is formed on the housing outer diameter side of the groove 136, that is, at the base portion of the third shoe 13.

On the other hand, the counterclockwise direction surface 444 of the fourth vane 44 is provided with a cylindrical hole 446 that supports the holding portion 632 of the third spring unit 63 over the most part. The diameter of the hole 446 is substantially the same as the diameter of the holding portion 632. The hole 446 restricts the movement of the holding portion 632 relative to the fourth vane 44, for example, the movement of the housing 10 in the radial direction.

During assembly, the third spring unit 63 is inserted into the fourth advance chamber A4 from the X-axis negative direction side, the holding portion 632 is fitted into the hole 446, and the holding portion 631 is engaged with the groove 136 for assembly. Do. As a result, the coil spring 630 is housed in the fourth advance chamber A4 in a compressed state, and the coil spring 630 always moves the fourth vane 44 clockwise with respect to the housing 10 (third shoe 13). Energize.

The other first and second spring units 61 and 62 are similarly provided. That is, one coil spring is provided in one advance chamber. One coil spring 610 provided in the second advance chamber A2 constantly urges the second vane 42 clockwise with respect to the housing 10 (first shoe 11). One coil spring 620 provided in the third advance chamber A3 constantly urges the third vane 43 clockwise with respect to the housing 10 (second shoe 12).

When the vane rotor 4 rotates with respect to the housing 10 in the clockwise direction, which is the direction in which the second to fourth vanes 42 to 44 are biased by the biasing means 6, the second to fourth advance chambers A2 to A4 are moved. As the volume increases, the length of the coil springs 610 to 630 increases. When the rotation amount (relative rotation angle) reaches a predetermined value, as shown in FIG. 2, the first vane 41 (the surface 415 on the clockwise direction side thereof) and the first shoe 11 (the surface 114 on the counterclockwise direction side thereof). Contact each other to restrict the relative rotation. At this time, other vanes and shoes, that is, the second vane 42 (the surface 425 on the clockwise direction side thereof), the second shoe 12 (the surface 124 on the counterclockwise direction side thereof), and the third vane 43 (the clockwise direction thereof). Side 435) and third shoe 13 (counterclockwise surface 134), fourth vane 44 (clockwise surface 445) and fourth shoe 14 (counterclockwise surface) 144) are not in contact with each other and have a slight distance between each other.

When the vane rotor 4 rotates relative to the housing 10 in the counterclockwise direction that is opposite to the direction in which the second to fourth vanes 42 to 44 are biased by the biasing means 6, the second to fourth advance angles. As the volumes of the chambers A2 to A4 are reduced, the coil springs 610 to 630 are compressed. When the rotation amount (relative rotation angle) reaches a predetermined value, as shown in FIG. 3, in the first advance chamber A1 where no spring unit is provided, the first vane 41 (the surface 414 on the counterclockwise direction side thereof) And the fourth shoe 14 (the surface 145 on the clockwise direction side) come into contact with each other to restrict the relative rotation. On the other hand, the oil chambers A2 to A4 provided with the first to third spring units 61 to 63 are not provided with a stopper for restricting the compression of the coil springs 610 to 630.

At this time, as shown in FIG. 3, other vanes and shoes other than the first vane 41 and the fourth shoe 14, that is, the second vane 42 (the surface 424 on the counterclockwise direction thereof) and the first shoe 11 (of the Clockwise surface 115), third vane 43 (counterclockwise surface 434), second shoe 12 (clockwise surface 125), and fourth vane 44 (counterclockwise direction). The side surface 444) and the third shoe 13 (the surface 135 on the clockwise side thereof) do not contact each other.

In addition, in each of the first to third spring units 61 to 63, the vane-side and shoe-side holding portions 611, 612 and the like do not contact each other, and the windings closely contact each other in the coil springs 610 to 630. do not do. In other words, when the first vane 41 and the fourth shoe 14 come into contact with each other to restrict the relative rotation, the circumferential clearances of the advance chambers A2 to A4 provided with the first to third spring units 61 to 63 are provided. Is set larger than the spring length when the windings of the coil springs 610 to 630 are completely in close contact with each other. For example, even if the gap between the second vane 42 (surface 424) and the first shoe 11 (surface 115) changes from the size in FIG. 2 to the size in FIG. 3, the coil spring 610 is compressed by that amount. The coil spring 610 is set such that a predetermined gap remains between the windings of the coil spring 610.

As described above, the first to third spring units 61 to 63 are provided on the second to fourth vanes 42 to 44 on the counterclockwise direction side (surfaces 424 to 444), respectively. Therefore, the center of gravity of the wide first vane 41 (provided with the lock mechanism 5 described later) and the center of gravity of the second to fourth vanes 42 to 44 (including the first to third spring units 61 to 63). Are provided at symmetrical positions at substantially equal intervals around the rotation axis O. As a result, the weight balance in the direction around the entire axis of the vane rotor 4 is balanced.

The first vane 41 and the rear plate 103 are provided with a lock mechanism 5 that restrains the rotation of the vane rotor 4 with respect to the rear plate 103 (sprocket 104) and releases the restraint. The lock mechanism 5 includes a lock piston 51, a lock hole constituent member (sleeve 52), a coil spring 53, and a spring retainer 54. 5 and 6 are partial cross-sectional views taken along the line CC of FIG. 2, and schematically show the operating state of the lock piston 51. FIG. FIG. 5 shows a state when the engine is stopped (when the engine is started), and FIG. 6 shows a state when the engine is operating.

A sliding hole 501 is formed through the first vane 41 in the X-axis direction. The sliding hole 501 has a small-diameter chamber 502 on the X-axis positive direction side and a large-diameter chamber 503 on the X-axis negative direction side. Inside the sliding hole 501, a covered cylindrical lock piston 51 is slidably installed in the X-axis direction. A tapered tip portion 511 having a substantially trapezoidal axial cross section is formed at the end of the lock piston 51 on the X axis positive direction side. A cylindrical sliding portion 512 is formed on the X axis negative direction side adjacent to the tip portion 511. An annular flange 513 is formed at the end on the X axis negative direction side adjacent to the sliding portion 512.

The diameter of the sliding portion 512 is substantially the same as the inner peripheral surface of the small diameter chamber 502 of the sliding hole 501. The sliding portion 512 is accommodated in the small diameter chamber 502 and slides with respect to the small diameter chamber 502. The diameter of the flange portion 513 is larger than that of the sliding portion 512 and substantially the same diameter as the inner peripheral surface of the large-diameter chamber 503 of the sliding hole 501. The flange portion 513 is accommodated in the large diameter chamber 503 and slides relative to the large diameter chamber 503. Inside the first vane 41, a stepped portion 504 is formed at the boundary between the small diameter chamber 502 and the large diameter chamber 503. The surface 508 of the stepped portion 504 on the X axis negative direction side and the X axis of the flange portion 513 are formed. A pressure receiving chamber 550 is formed between the surface on the positive direction side.

On the other hand, a fixing hole 505 is formed through the rear plate 103 in the X-axis direction. A cup-shaped sleeve 52 is fixed to the fixing hole 505. The rear plate 103 (sprocket 104) is provided with a sleeve locking portion 107 that restricts the movement of the sleeve 52 in the positive x-axis direction (see FIG. 1). The sleeve 52 abuts on the rear plate 103 at the sleeve locking portion 107 and is locked. In the sleeve 52, a lock hole 521 having a substantially trapezoidal axial section and gradually increasing in diameter toward the opening is formed from the X axis positive direction side.

A spring retainer 54 is installed on the X axis negative direction side of the large diameter chamber 503. Between the spring retainer 54 and the lock piston 51, a coil spring 53 is installed in a compressed state. The coil spring 53 moves the lock piston 51 from the X axis positive direction side, that is, the rear plate 103 (lock hole 521). ) Is always energized in the direction of).

When the vane rotor 4 rotates relative to the most advanced angle side, that is, the first vane 41 (the surface 415 on the clockwise direction side thereof) and the first shoe 11 (the surface 114 on the counterclockwise direction side) come into contact with each other, and the retarding chamber. When the volume of R1 is minimized, the position of the lock piston 51 and the position of the lock hole 521 overlap substantially coaxially when viewed from the X-axis direction. At this time, the lock piston 51 is pressed by the spring force of the coil spring 53 and moves in the positive direction of the X axis, and the distal end portion 511 is fitted into the lock hole 521 so that the lock piston 51 is engaged with the lock hole 521. . Thereby, the relative rotation between the rear plate 103 and the vane rotor 4, that is, the relative rotation between the sprocket 104 and the camshaft 3 is locked.

As shown in FIG. 5, the first vane 41 is formed with a communication hole 506 that communicates the advance chamber A <b> 1 and the pressure receiving chamber 550. Similarly, the first vane 41 is formed with a communication groove 507 for communicating the retard chamber R1, the lock hole 521, and the small-diameter chamber 502 on the surface in the positive X-axis direction. The lock piston 51 receives oil pressure on the negative side in the X-axis at the flange portion 513 by the hydraulic pressure supplied from the advance chamber A1 into the pressure receiving chamber 550 through the communication hole 506.

Further, the lock piston 51 receives hydraulic pressure on the X axis negative direction side at the distal end portion 511 by the hydraulic pressure supplied from the retard chamber R1 into the lock hole 521 through the communication groove 507. The lock piston 51 moves to the X-axis negative direction side against the spring force of the coil spring 53 by any of the above oil pressures. As a result, the engagement between the lock piston 51 and the lock hole 521 is released.

Thus, the coil spring 53 functions as a lock state maintaining mechanism. The spring force is compressed by the operating oil pressure that has been retained in the advance chamber A1 from the pump P (described later) and pumped into the advance chamber A1 when the engine is started. Even if the portion 513 is pressed, the coil spring 53 is not greatly compressed and deformed by this, so that the engagement between the lock piston 51 and the lock hole 521 is not released.

When the mechanism 1 is assembled, first, the vane rotor 4 is inserted into the main body 102 of the housing 10, the lock pin 51 is inserted into the sliding hole 501, and the coil spring 53 and the spring retainer 54 are inserted into the lock pin 51. Next, the spring units 62 to 63 are engaged with the advance chambers A2 to A4, respectively, and the rear plate 103 (sprocket 104) is brought into contact with the main body 102 from the X axis positive direction side. At that time, the sleeve 52 and the sleeve locking portion 107 are coaxial with the sliding hole 501. Then, the front plate 101 is brought into contact with the main body portion 102 from the X-axis negative direction side and fastened by bolts b1 to b4 to integrate the members.

The hydraulic supply / discharge mechanism 2 supplies the hydraulic oil to the advance chambers A1 to A4 or the retard chambers R1 to R4 and discharges them to rotate the vane rotor 4 forward and backward by a predetermined angle with respect to the housing 10 (sprocket 104). Let That is, by adjusting the supply and discharge of hydraulic oil and changing the volume of the oil chamber, the housing 10 is rotated relative to the vane rotor 4, and the rotational force is transmitted between the two in this state, so that the crankshaft The rotational phase of the camshaft 3 with respect to the rotation is changed. As shown in FIG. 1, the hydraulic supply / discharge mechanism 2 has a pump P that is a hydraulic supply source, an oil flow path, and a flow path switching valve 24 that is a hydraulic control actuator.

The oil flow path has two paths, that is, an advance passage 20 for supplying and discharging hydraulic oil to and from each advance chamber A1 to A4, and a delay for supplying and discharging hydraulic oil to each retard chamber R1 to R4. An angular passage 21 is provided. A supply passage 22 that is a main oil gallery and a drain passage 23 are connected to both the passages 20 and 21 via a passage switching valve 24. The supply passage 22 is provided with a pump P that pumps oil in the oil pan 26. As the pump P, for example, a unidirectional variable displacement vane pump can be used. The downstream end of the drain passage 23 communicates with the oil pan 26.

A part of the advance passage 20 and the retard passage 21 is constituted by a hydraulic pressure supply block 25. The hydraulic pressure supply block 25 is inserted into the fitting hole 403 of the vane rotor 4 from the X axis negative direction side and is fitted to the fitting hole 403 so as to be relatively rotatable. Inside the hydraulic pressure supply block 25, a first passage 200 that is a trunk passage of the advance passage 20 and a second passage 210 that is a trunk passage of the retard passage 21 are formed in the X-axis direction. By using the hydraulic pressure supply block 25 in this way, it is not necessary to form an axial oil passage or the like on the camshaft 3 side, and the number of processing steps for the camshaft 3 can be reduced.

The first passage 200 opens at the end surface of the hydraulic pressure supply block 25 on the X axis positive direction side. On the outer periphery of the hydraulic pressure supply block 25, an oil seal is provided at the end on the X axis positive direction side to ensure liquid tightness with the inner peripheral surface of the fitting hole 403. A first hydraulic port 251 is formed between the end surface of the hydraulic pressure supply block 25 on the X axis positive direction side, the inner peripheral surface of the fitting hole 403 on the X axis positive direction side, and the oil seal. The first hydraulic port 251 accommodates the head portion of the cam bolt 31.

The second passage 210 communicates with an oil groove 253 formed on the outer periphery of the hydraulic pressure supply block 25 through an oil hole 252. An oil seal is provided on the outer periphery of the hydraulic pressure supply block 25 to secure the liquid tightness of the oil groove 253 with both sides of the oil groove 253 in the X-axis direction interposed therebetween. A second hydraulic port 254 is formed between the outer peripheral surface (oil groove 253) of the hydraulic pressure supply block 25, the inner peripheral surface of the fitting hole 403 on the X axis negative direction side, and the oil seal.

The advance passage 20 is provided between the flow path switching valve 24 and each of the advance chambers A1 to A4, and includes a first passage 200 and four branch passages 201, 202, 203, and 204. The first passage 200 communicates from the flow path switching valve 24 to the inside of the hydraulic pressure supply block 25 and communicates with the first hydraulic pressure port 251. The branch passages 201 to 204 are branched into a radial shape when viewed from the X-axis direction inside the rotor 40 (see FIG. 2), communicate with the first hydraulic port 251 on the inner diameter side, and advance on the outer diameter side. It communicates with the corner chambers A1 to A4.

The retard passage 21 is provided between the flow path switching valve 24 and each of the retard chambers R1 to R4, and includes a second passage 210 and four branch passages 211, 212, 213, and 214. The second passage 210 communicates from the flow path switching valve 24 to the inside of the hydraulic pressure supply block 25 and communicates with the second hydraulic pressure port 254. The branch passages 211 to 214 are branched radially in the rotor 40 as viewed from the X-axis direction (see FIG. 2). The branch passages 211 to 214 communicate with the second hydraulic port 254 on the inner diameter side and slow on the outer diameter side. It communicates with the corner chambers R1 to R4.

The flow path switching valve 24 is a direct acting solenoid valve (a directional control valve at 4 ports and 3 positions), and controls the hydraulic pressure supplied to and discharged from the advance chambers A1 to A4 or the retard chambers R1 to R4. The flow path switching valve 24 has a valve body fixed to the cylinder head, a solenoid fixed to the valve body, and a spool valve body slidably provided inside the valve body. The valve body includes a supply port 240 that communicates with the supply passage 22, a first port 241 that communicates with the advance passage 20, a second port 242 that communicates with the retard passage 21, and a drain port 243 that communicates with the drain passage 23. Is formed.

The solenoid presses and moves the spool valve body by energizing the electromagnetic coil. The electromagnetic coil is connected to the controller CU via a harness. As the spool valve element moves, the first port 241 and the second port 242 are opened and closed.

When the solenoid is not energized, the spool valve body is displaced to the maximum in the negative direction of the X axis by the spring force of the return spring RS, and the supply port 240 and the first port 241 communicate with each other, and the second port 242 and the drain port It is urged to the position where it communicates with 243. On the other hand, with the solenoid energized, the spool valve body is controlled to move to the maximum position on the X-axis positive direction side or the predetermined intermediate position against the spring force of the return spring RS by the control current from the controller CU. It has come to be.

The controller CU is an electronic control unit that receives signals from various sensors such as a crank angle sensor that detects the engine speed, an air flow meter that detects the intake air amount, a throttle valve opening sensor, and a water temperature sensor that detects the engine water temperature. To detect the current engine operating state. Further, the controller CU applies a pulse control current to the electromagnetic coil of the flow path switching valve 24 according to the engine operating state, or cuts off the power supply, and performs flow path switching control, so that the advance chambers A1 to A1. Selectively supply and discharge hydraulic oil to / from A4 or retarded angle chambers R1 to R4.

(Operation of variable valve timing mechanism)
Hereinafter, the operation of the VTC will be described with reference to the drawings. 2 shows a state when the engine is stopped (when the engine is started), and FIG. 3 shows a state when the engine is rotating. The vane rotor 4, the housing 10, the advance chambers A1 to A4 and the retard chambers R1 to R4, the hydraulic supply / discharge mechanism 2 and the like constitute a phase change mechanism (VTC).

During engine operation, during rotation of the camshaft 3, so-called alternating torque is generated in the camshaft 3 due to the rotational reaction force transmitted from the valve spring of the exhaust valve to the cam of the camshaft 3. That is, due to the cam shape, a positive torque (counterclockwise) that prevents the camshaft 3 from rotating (clockwise) and a negative torque that assists the rotation of the camshaft 3 (clockwise) are: It acts on the camshaft 3 alternately. Due to the resistance at the contact surface between the cam of the camshaft 3 and the valve side member, the alternating torque is offset to the positive torque side as a whole. In other words, when the positive torque and the negative torque generated at each rotation period of the camshaft 3 are integrated over time, the camshaft 3 becomes positive and acts on the camshaft 3 on average.

When the engine stops, the operation of the pump P is stopped. Further, the energization from the controller CU to the flow path switching valve 24 is interrupted. Therefore, the supply of hydraulic pressure to the advance chambers A1 to A4 and the retard chambers R1 to R4 is stopped. Further, immediately after the engine is stopped, the vane rotor 4 is rotated with respect to the housing 10 by the alternating torque generated in the camshaft 3 (offset to the positive torque side) (the arrow in FIG. 2). Counterclockwise direction opposite to (direction), that is, to move to the retard side.

On the other hand, the vane rotor 4 is urged to the housing 10 by the urging means 6 (first to third spring units 61 to 63) in the same clockwise direction as the rotation direction of the sprocket 104, that is, the advance side. Yes. Therefore, after the engine is stopped, the vane rotor 4 is not affected by the alternating torque, and is in accordance with the urging force in advance to a predetermined initial position suitable for engine (re) starting, that is, the most advanced angle side position shown in FIG. Moving. (This is the same not only when the engine is stopped but also when the oil pressure is low, such as when idling.) In other words, the valve timing is in a phase suitable for engine (re) starting. In the most advanced state, the volumes of the advance chambers A1 to A4 are maximized, while the volumes of the retard chambers R1 to R4 are minimized.

Further, when the vane rotor 4 rotates relative to the housing 10 toward the most advanced angle side, the position of the lock piston 51 of the lock mechanism 5 and the position of the lock hole 521 overlap, so that when the engine is stopped, as shown in FIG. Due to the spring force of the coil spring 53, the tip end portion 511 is fitted and engaged in the lock hole 521, and the lock piston 51 restricts free rotation of the vane rotor 4. As a result, when the engine is restarted, control can be performed from the initial position of the VTC regardless of whether or not hydraulic pressure is generated, and the flicker between the vane rotor 4 and the housing 10 caused by the alternating torque acting on the camshaft 3 at the time of engine restart. (Generation of abnormal noise due to collision) can be prevented.

Next, when the ignition key is turned on to start the engine, the control current from the controller CU is not output to the flow path switching valve 24 for a few seconds from the start of cranking. The spool valve body is urged to the maximum position on the X-axis negative direction side by the spring force of the return spring RS, and the supply port 240 and the first port 241 communicate with each other, and the second port 242 and the drain port 243 communicate with each other. . Therefore, the hydraulic pressure discharged from the pump P flows into the valve body from the supply passage 22 through the supply port 240, and flows into the first passage 200 from the first port 241 as it is, and from here, each branch passage 201 ˜204 and supplied to the advance chambers A1 to A4. The internal pressure of each advance chamber A1 to A4 increases as the discharge pressure of the pump P increases.

As the internal pressure of the advance chamber A1 rises, this hydraulic pressure is supplied to the pressure receiving chamber 550 from the communication hole 506 (see FIG. 5), and acts on the pressure receiving surface of the flange portion 513 of the lock piston 51 as oil pressure. When the discharge pressure of the pump P becomes equal to or higher than the predetermined value P1, the oil pressure becomes larger than the spring force of the coil spring 53, and the lock piston 51 moves in the X axis positive direction. When the tip 511 is completely removed from the lock hole 521, the locked state is released. That is, free rotation of the vane rotor 4 is allowed, and the valve timing can be arbitrarily changed. The predetermined pressure P1 at which the locked state is released is realized temporally after about 2 to 3 seconds have elapsed since the ignition key was turned on.

Even after the locked state is released, when the discharge pressure of the pump P is equal to or higher than P1 and lower than the predetermined pressure P2, the vane rotor 4 stops the engine by the relatively low operating hydraulic pressure supplied into each of the advance chambers A1 to A4. The state of being positioned on the most advanced angle side of the hour is maintained. Therefore, the engine startability is improved. At this time, the air staying in each of the advance chambers A1 to A4 is pressed by the hydraulic pressure and functions to push the vane rotor 4 to the most advanced angle side together with the hydraulic pressure.

After the cranking, when the engine speed rises to the middle speed range, the discharge pressure of the pump P becomes P2 or more. When the flow path switching valve 24 is energized from the controller CU, the spool valve element moves in the X axis positive direction. When the maximum position in the X-axis positive direction is reached, the spool valve body communicates the supply port 240 and the second port 242 and communicates the first port 241 and the drain port 243.

For this reason, the discharge pressure of the pump P flows into the second passage 210 from the supply passage 22 through the supply port 240 and the second port 242 and from there through the branch passages 211 to 214, each retard chamber R1. Supplied to ~ R4. Therefore, the inside of each retardation chamber R1 to R4 becomes high pressure. On the other hand, since the hydraulic oil in each advance chamber A1 to A4 is returned to the oil pan 26 from the first drain port 243 via the first passage 200 and the like, the inside of each advance chamber A1 to A4 becomes low pressure.

At this time, although the hydraulic pressure in the pressure receiving chamber 550 decreases in the lock mechanism 5, the lock piston 51 is now moved by the high hydraulic pressure supplied from the communication groove 507 to the tip 511 as the hydraulic pressure in the retard chamber R 1 increases. Receives oil pressure on the negative side of the X axis. As a result, the release state in which the lock piston 51 is pulled out of the lock hole 521 against the spring force of the coil spring 53 is maintained.

On the other hand, the hydraulic pressure in each of the retard chambers R1 to R4 increases due to the hydraulic pressure greater than or equal to P2 discharged from the pump P. 2, the vane rotor 4 rotates relative to the housing 10 from the position shown in FIG. 2 in the counterclockwise direction opposite to the rotation direction of the sprocket 104 (housing 10) (the arrow direction in FIG. 2). To do. As a result, the rotational phase of the camshaft 3 relative to the crankshaft is quickly changed to the retard side, and the valve overlap, which is the period during which both the intake valve and the exhaust valve are opened, is slightly increased.

When the hydraulic pressure in each of the retard chambers R1 to R4 decreases due to a decrease in the engine speed or the like, the relative rotational phase is quickly returned to the advance side, and the valve overlap is reduced. At this time, since the discharge pressure of the pump P is P2 or more, the unlocked state is maintained.

When the engine speed further increases, the discharge pressure of the pump P becomes P3 or higher. Further, energization from the controller CU to the flow path switching valve 24 is maintained, and high hydraulic pressure is continuously supplied to each of the retard chambers R1 to R4. For this reason, the vane rotor 4 further rotates in the counterclockwise direction to change the rotational phase of the camshaft 3 further to the retard side. Finally, as shown in FIG. 3, the vane rotor 4 is held at a position on the most retarded angle side where the volumes of the retarded angle chambers R1 to R4 are maximized, thereby maximizing the valve overlap. In the most retarded state, the volumes of the advance chambers A1 to A4 are minimized while the volumes of the retard chambers R1 to R4 are maximized.

(Function and effect)
As described above, at the time of engine stop or idling when the working hydraulic pressure of the VTC becomes zero or lowers, the urging force of the urging means 6 causes the vane rotor 4 to move to the housing 10 without being affected by the alternating torque. Rotate to the initial position on the advance side. Therefore, the VTC can be controlled from the initial position even when the engine is restarted or idle, and the mechanism 1 can be stably operated.

Further, the relative rotation between the housing 10 and the vanes (first to fourth vanes 41 to 44) can be restricted by operating the locking means (lock mechanism 5) at the initial position. That is, even in a state where no hydraulic pressure is generated, the housing 10 and the vane rotor 4 can be held, and the VTC can be controlled from the initial position regardless of whether the hydraulic pressure is generated. As a result, the mechanism 1 can be stably operated even when the engine is started or idling, while preventing flutter and abnormal noise between the vane rotor 4 and the housing 10 caused by the alternating torque.

Then, when the operating hydraulic pressure of the VTC rises and the lock is released and the valve timing is changed to the retard side, the vane rotor 4 is rotated relative to the housing 10. At that time, the fourth shoe 14 and the first vane 41 are brought into contact with each other to prevent relative rotation of a predetermined amount or more. That is, the fourth shoe 14 and the first vane 41 abut at the most retarded angle position in the advance chamber A1, thereby exhibiting a stopper function and restricting relative rotation. At this time, the other shoes and the vanes are not in contact with each other, and a state in which a predetermined volume (a circumferential interval in which the spring units 61 to 63 are not completely reduced) is secured in the advance chambers A2 to A4 is maintained. ing.

Since the displacement amount (compression amount) of the urging means 6 is regulated to a predetermined amount or less by this stopper function, plastic deformation of the urging means 6 can be prevented and the urging force can be prevented from changing irreversibly. In other words, the contact surface between the fourth shoe 14 and the first vane 41 is provided at a position where the spring units 61 to 63 are not completely contracted when abutting at the most retarded position. In the most retarded state, the fourth shoe 14 and the first vane 41 come into contact with each other and the rotation is restricted before the spring units 61 to 63 are completely contracted.

Therefore, at any rotational phase, the vane-side and shoe-side holding portions 611, 612 and the like do not come into contact with each spring unit 61-63, and the coil springs 610-63 of each spring unit 61-63. 630 is not fully reduced. Therefore, even in the most retarded state, the spring units 61 to 63 are not compressed to the contact length, the spring lines do not interfere with each other, and a gap between the spring lines can be secured to avoid contact between the lines. The plastic deformation of the urging means 6 and the change of the urging force can be prevented.

Here, suppose that the stopper means for restricting the compression amount of the urging means 6 is provided not in the oil chamber A1 where the urging means 6 is provided but in the oil chambers A2 to A4 where the urging means 6 is provided. The space for arranging the biasing means 6 is limited by the space provided with the stopper means. In other words, the upper limit of the size of the urging means 6 is reduced, and the urging force cannot be increased by a predetermined amount or more. In order to increase the urging force, it is necessary to enlarge the oil chambers A2 to A4 to secure a space, but in this case, the VTC is enlarged. For example, when the holding part of the urging means 6 and the contact part having the stopper function are provided together on one side surface 424 of the second vane 42, one of the area for the holding part and the area for the contact part is provided. If the area of is increased, the other area is reduced.

On the other hand, in the first embodiment, the relative rotation of the housing 10 and the vane rotor 4 is restricted by the contact between the shoe 14 and the vane 41 in which the biasing means 6 is not provided between them. In other words, since the stopper at the time of compression of the urging means 6 is provided in the oil chamber A1 where the urging means 6 is not provided, the arrangement space of the urging means 6 is not restricted. Therefore, the urging force can be increased by increasing the size of the urging means 6. In other words, the urging force can be increased while reducing the size of the VTC. For example, the holding portion of the biasing means 6 and the contact portion having a stopper function are not provided on the same side surface of the vane, but are provided separately on different vanes 41 (contact portion) and 42 to 44 (holding portion). Therefore, both areas can be enlarged.

Further, the first vane 41 including the contact portion with the fourth shoe 14 is formed in the same shape in the rotation axis direction (X-axis direction), and is integrally formed by die molding when the vane rotor 4 is sintered. . Therefore, it is not necessary to provide a special rotation restricting mechanism (stopper mechanism) in another part, and the stopper mechanism can be configured easily. In the first embodiment, the fourth shoe 14 and the first vane 41 are brought into surface contact. However, the fourth shoe 14 is formed with a protruding portion that protrudes toward the first vane 41. It is good also as 1 vane 41 contacting. Further, the convex portion may be formed on the first vane 41 side.

Further, between the shoe 11 to 14 and the vane 42 to 44 to form an oil chamber A2～A 4 the first vane 41 having a locking means (locking mechanism 5) excluding the oil chamber A1 to rotate relative to the housing 10 The biasing means 6 for biasing the vanes 42 to 44 in one direction is provided. That is, the first vane 41 having the lock mechanism 5 is heavier than the other vanes 42 to 44. Therefore, the center of gravity of the mechanism 1 attached to the camshaft 3 is biased toward the first vane 41 having the lock mechanism 5, the balance of the mechanism 1 is deteriorated, and vibration occurs when the VTC is activated (when the camshaft 3 is rotated). It was the cause that occurred. In the first embodiment, by providing the urging means 6 to the vanes 42 to 44 excluding the first vane 41, the weight balance around the axis O of the vane rotor 4 is improved, and the unbalance amount is reduced. As a result, vibration during VTC operation can be suppressed.

Further, the vane that restricts relative rotation by contact in the advance direction and the retard direction is the same, and is the first vane 41 having the lock mechanism 5. That is, the first vane 41 having the lock mechanism 5 is in contact with the adjacent first shoe 11 on the urging direction side of the urging means 6 at the most advanced angle position (FIG. 2) and urged at the most retarded angle position. The fourth shoe 14 adjacent to the direction opposite to the direction also contacts (FIG. 3). In the most advanced position, oil pressure acts on the first vane 41 having the lock mechanism 5 in addition to the urging force of the urging means 6. However, since the first vane 41 having the lock mechanism 5 is thick in the circumferential direction, the first vane 41 is advantageous in that it has sufficient rigidity and sufficient strength for restricting relative rotation.

The lock means (lock mechanism 5) is a lock piston 51 housed inside the first vane 41, and locks the relative rotation of the housing 10 and the vane rotor 4 by operating in the axial direction. Release the stop. That is, since the lock piston 51 automatically engages with the lock hole 521 when the vane rotor 4 is rotated to a predetermined initial position by the urging force of the urging means 6, an actuator for the lock operation is particularly required. do not do. Therefore, the mechanism is simpler than the case where a clutch mechanism or a lever mechanism is used as the locking means, and the reliability of the locking operation can be ensured while reducing the cost.

The biasing means 6 is a coil spring, and one coil spring 610 to 630 is accommodated in each of the advance chambers A 2 to A 4 . By using such a coil spring, for example, compared with the case of using a leaf spring or the like, it tends to adjust the biasing force, also good assemblability easily installed in the oil chamber A2~A 4. Also, by housing one for each oil chamber A2～A 4, it can be downsized mechanism 1. For example, when accommodating stacked in the axial direction by two coil springs to each of the oil chambers A2~A 4, mechanism 1 is increased in size in the axial direction. Also, installing the two coil springs when placed in the oil chamber A2～A 4, unless they were installed in the oil chamber A2～A 4 while the installation to one spring unit to the holder (holding portion) Is difficult. In contrast, when accommodating one by one to the respective oil chambers A2～A 4 as in the first embodiment, not only it is easy assembled, the coil spring 610 to 630 holder (such as holding portions 611 and 612) directly without integrated into it is also possible to place the oil chamber A2～A 4, in this case, the number of parts can be reduced by omitting the holder.

The first vane 41 having the lock mechanism 5 communicates with the oil chamber (advance chamber A1) whose volume is increased by the urging force of the urging means 6 to operate (unlock) the lock mechanism 5. A passage (communication hole 506) is formed. That is, the vanes 42 to 44 provided with the urging means 6 need to be provided with a groove 446 and the like for holding the urging means 6 (see FIG. 4). On the other hand, the first vane 41 provided with the lock mechanism 5 communicates with the oil chamber A1 to operate the lock mechanism 5 in order to realize engagement / release of the lock mechanism 5 according to the operation of the VTC. It is easy to form a passage (communication hole 506) for supplying the oil. In the first embodiment, since the urging means 6 is not provided in the oil chamber A1 in which the first vane 41 having the lock mechanism 5 rotates, the passage (communication hole 506) holds the urging means 6. It does not interfere with the grooves and members necessary for the operation. Therefore, the passage (communication hole 506) can be freely arranged, and the degree of freedom in design is high.

[Effect of Example 1]
Hereinafter, effects of the variable valve timing mechanism 1 of the present invention ascertained from the first embodiment will be listed.

(1) In the variable valve timing mechanism 1 of the internal combustion engine, the rotational force of the crankshaft is transmitted, and the rotational force is transmitted to the housing 10 having a plurality of convex shoes 11 to 14 on the inner peripheral side and the camshaft 3. The same number of vanes 41 to 44 as the shoes 11 to 14 provided so as to be rotatable relative to the housing 10 and relatively rotated between the shoes 11 to 14, the rotor 40 integrated with the vanes 41 to 44, and the above The vane rotor 4 having a lock means (lock mechanism 5) capable of restricting relative rotation, the oil chambers separated by the circumferentially adjacent shoes 11-14 and the rotor 40, and the oil chambers are the vanes 41-44. The advance chambers A1 to A4 and the retard chambers R1 to R4 separated by the oil passages (branch passages 201 to 204, for supplying and discharging oil to and from the advance chambers A1 to A4 or the retard chambers R1 to R4) 211 to 214) and the housing 10 The vanes 42 to 44 are urged in one direction (clockwise direction), and when the housing 10 and the vane rotor 4 are rotated relative to each other in the direction opposite to the direction in which the vanes 42 to 44 are urged, the vanes 42 to 44 come into contact with each other. Urging means 6 (first to third spring units 61 to 63) provided between the shoes 11 to 13 and the vanes 42 to 44 "excluding" the fourth shoe 14 and the first vane 41 that restrict movement; It was decided to have.

In other words, when the housing 10 and the vane rotor 4 are relatively rotated in a direction opposite to the direction in which the vanes 42 to 44 are urged by the urging means 6, the fourth shoe 14 is brought into contact with each other to restrict the relative rotation. The first vane 41 is provided, and the urging means 6 is provided between the fourth shoe 14 that restricts relative rotation and the shoes 11 to 13 excluding the first vane 41 and the vanes 42 to 44.

Therefore, since the displacement amount (compression amount) of the urging means 6 is restricted to a predetermined amount or less by the stopper function due to the contact between the fourth shoe 14 and the first vane 41, the plastic deformation of the urging means 6 is prevented, The urging force can be prevented from changing irreversibly. Therefore, the change of the urging force of the urging means 6 can be prevented and the mechanism can be operated more stably.
Further, the oil chamber A 1 that biasing means 6 is not provided with the stopper function is provided, never space for disposing the urging means 6 is restricted. Therefore, there is an effect that the urging force can be arbitrarily adjusted while the size of the mechanism 1 is reduced.

(2) A vane with respect to the housing 10 between the shoes 11 to 13 and the vanes 42 to 44 forming the oil chambers A2 to A4 excluding the oil chamber A1 in which the vane 41 having the lock means (lock mechanism 5) rotates. An urging means 6 for urging 42 to 44 in one direction is provided.

Therefore, by restricting the relative rotation of the vane rotor 4 and the housing 10 by the locking means, it is possible to prevent fluttering and abnormal noise between the two, and to stably operate the mechanism 1 even when the engine is started or idle. it can. Further, by providing the urging means 6 to the vanes 42 to 44 excluding the vane 41 having the locking means, the weight balance around the axis O of the vane rotor 4 can be improved, and vibration during VTC operation can be suppressed. Play.

(3) The lock means is a lock piston 51 housed in the vane 41 and operates in the axial direction to lock the relative rotation of the housing 10 and the vane rotor 4 or to release the lock.
Therefore, the mechanism 1 is simple, and it is possible to secure the reliability of the lock operation while reducing the cost.

(4) The biasing means 6 is a coil spring, and one coil spring 610 to 630 is accommodated in each of the advance chambers A2 to A4.
Therefore, it is easy to adjust the urging force by using the coil spring, and the assembling property is good. Further, the mechanism can be reduced in size by storing one in each of the oil chambers A2 to A4.

(5) A passage for supplying oil for operating the locking means to the vane 41 having the locking means (locking mechanism 5), which communicates with the oil chamber A1 whose volume is increased by the urging force of the urging means 6. A communication hole 506) was formed.
Therefore, since the urging means 6 is not provided in the oil chamber A1 in which the vane 41 having the locking means rotates, an oil passage for operating the groove 446 and the member for holding the urging means 6 and the locking means. (Communication hole 506) does not interfere and the degree of freedom in design is high.

Reference example

(Configuration of reference example )
The variable valve timing mechanism 1 of the reference example excludes a shoe and a vane that come into contact with each other and restrict the relative rotation when the housing 10 and the vane rotor 4 rotate relative to each other in the direction opposite to the direction in which the vane is urged. In common with the first embodiment, biasing means 6 (first to third spring units 61 to 63) is provided between the shoe and the vane. However, the point which the vane which has the said stopper function is not the 1st vane 41 but the 3rd vane 43, and the width of the circumferential direction between the 1st-4th shoes 11-14 differ from Example 1. FIG. Other configurations are the same as those of the first embodiment.

7 and 8 show the mechanism 1 of the reference example , and are sectional views similar to FIGS. 2 and 3 (cross section taken along line AA in FIG. 1), respectively. Hereinafter, the same reference numerals are given to the portions corresponding to the first embodiment, and the description thereof will be omitted, and only different portions will be described.

The arrangement of the first to fourth shoes 11 to 14 in the reference example is the same as the arrangement of the first embodiment in that the third and fourth shoes 13 and 14 are arranged with the axial center O (while maintaining the same circumferential interval). Is shifted by a predetermined angle in the counterclockwise direction. Thereby, the circumferential direction space | interval between the 2nd shoe 12 and the 3rd shoe 13 is provided narrower than Example 1, and is narrower than the circumferential direction space | interval between other shoes. Moreover, the circumferential direction space | interval between the 4th shoe 14 and the 1st shoe 11 is provided more widely than Example 1, and is wider than the circumferential direction space | interval between other shoes. The circumferential intervals between the first shoe 11 and the second shoe 12 and between the third shoe 13 and the fourth shoe 14 are the same as in the first embodiment. The circumferential width of the first to fourth shoes 11 to 14 themselves and the circumferential width of the first to fourth vanes 41 to 44 are the same as those in the first embodiment.

In other words, the second and third shoes 12 and 13 on both sides in the circumferential direction of the third vane 43 opposite to the first vane 41 (having the lock mechanism 5) sandwiching the axis O of the vane rotor 4 are located on the axis O. The angle formed with respect to each other (for example, the position of the center of gravity of each shoe or the intermediate position in the circumferential direction of each shoe can be used as a reference for such an angle). The shoes (the fourth shoe 14 and the first shoe 11, the first shoe 11 and the second shoe 12, the third shoe 13 and the fourth shoe 14) are made smaller than the angles formed with respect to the axis O, respectively.

In addition, the angle formed by the first and fourth shoes 11, 14 on both sides in the circumferential direction of the first vane 41 (having the lock mechanism 5) with respect to the axis O is the shoe on both sides in the circumferential direction of the other vanes 42 to 44. (The first shoe 11 and the second shoe 12, the second shoe 12 and the third shoe 13, the third shoe 13 and the fourth shoe 14) are made larger than the angles formed with respect to the axis O, respectively.

The biasing means 6 has three spring units, that is, first, third, and fourth spring units 61, 63, and 64. Spring units 61, 63, and 64 are provided in the three advance chambers A2, A4, and A1, respectively. In the oil chamber between the second shoe 12 and the third shoe 13 provided with a narrow circumferential interval, the urging means 6 (second spring unit 62) is not provided in the third advance chamber A3. On the other hand, in the oil chamber between the fourth shoe 14 and the first shoe 11 having a wide circumferential interval, it is attached between the fourth shoe 14 and the first vane 41 (first advance chamber A1). A biasing means 6 (fourth spring unit 64) is provided, and biases the first vane 41 clockwise with respect to the housing 10 (fourth shoe 14).

In other words, the shoe that forms the oil chambers A2, A4, and A1 excluding the oil chamber A3 in which the third vane 43 opposite to the first vane 41 (having the lock mechanism 5) sandwiches the axis O. Biasing means 6 (spring units 61, 63, 64) for biasing the vanes 41, 42, 44 in one direction with respect to the housing 10 is provided between the 11, 13, 14 and the vanes 41, 42, 44. Is provided.

The fourth spring unit 64 has one coil spring 640 and holding portions 641 and 642 provided at both ends thereof. The urging forces of the coil springs 610, 630, and 640 are substantially the same. A groove 146 that supports the holding portion 641 is provided on the surface 145 of the fourth shoe 14 on the clockwise direction side. A guide portion 147 is formed on the outer diameter side of the housing of the groove 146 (the root portion of the fourth shoe 14). On the other hand, a hole 416 for supporting the holding portion 642 is provided in the surface 414 on the counterclockwise direction side of the first vane 41.

(Function)
As described above, the first vane 41 having the lock mechanism 5 is heavier than the other vanes 42 to 44, and thus causes vibration when the VTC is operated (when the camshaft 3 is rotated). In this reference example , the angle formed by the second and third shoes 12 and 13 on both sides in the circumferential direction of the third vane 43 on the opposite side across the first vane 41 and the axis O is the other shoe. It is smaller than the angle formed by. For this reason, the distance between the center of mass of the combined mass of the shoes 12 and 13 and the axis O is increased, the weight (moment of inertia) of the housing 10 opposite to the first vane 41 is increased, and the first vane 41 is increased. Negate the weight of. As a result, the weight balance around the axis O of the mechanism 1 is improved, the unbalance amount is reduced, and vibration during VTC operation is suppressed.

Further, the angle formed by the first and fourth shoes 11 and 14 on both sides in the circumferential direction of the first vane 41 with respect to the axis O is larger than the angle formed by the other shoes (so to speak, the first and fourth shoes). The amount of meat removal between 11 and 14 is increased). Therefore, the distance between the center of gravity of the combined mass of the shoes 11 and 14 and the axis O is reduced, the weight (moment of inertia) of the housing 10 on the first vane 41 side is reduced, and the first vane 41 Counter weight. This improves the weight balance around the axis O of the mechanism 1 and suppresses vibration during VTC operation, as described above.

Further, unlike the first embodiment, vanes that restrict the relative rotation of the housing 10 and the vane rotor 4 by being in contact with the shoe are provided separately according to the direction of the relative rotation. In other words, the advance angle direction contact portion and the retard angle direction contact portion that restrict relative rotation of the housing 10 and the vane rotor 4 by contacting the shoe and the vane are provided in different vanes.

That is, when the vane rotor 4 is rotated with respect to the housing 10 in the clockwise direction (advance direction) in which the vanes 41, 42, and 44 are urged by the urging means 6, as shown in FIG. As in Example 1, the first vane 41 (the surface 415 on the clockwise direction side thereof) and the first shoe 11 (the surface 114 on the counterclockwise direction side thereof) come into contact with each other to restrict the relative rotation.

On the other hand, when the vane rotor 4 rotates with respect to the housing 10 in the counterclockwise direction (retarding direction) opposite to the urging direction by the urging means 6, as shown in FIG. The vane 43 (the surface 434 on the counterclockwise direction side) and the second shoe 12 (the surface 125 on the clockwise direction side) come into contact with each other to restrict the relative rotation. Since the amount of displacement of the biasing means 6 (spring units 61, 63, 64) is regulated to a predetermined value or less by this stopper function, plastic deformation of the biasing means 6 is prevented, and irreversible changes in the biasing force can be prevented.

In this way, the vane that restricts relative rotation by contact differs between the advance angle direction and the retard angle direction, and is the first vane 41 in the advance angle direction and the third vane 43 in the retard angle direction. Therefore, the strength of one vane is small. In other words, even if the rigidity of each of the vanes 41 and 43 is relatively small, a sufficient strength for restricting the relative rotation can be obtained.

The vane that restricts relative rotation in the advance direction is the first vane 41 having the lock mechanism 5, and the first vane 41 (surface 415) is adjacent to the first biasing direction side of the biasing means 6. It contacts the shoe 11 (surface 114) (FIG. 7). On the other hand, the vane that restricts relative rotation in the retarding direction is the third vane 43 that does not have the lock mechanism 5, and the third vane 43 (surface 434) is adjacent to the second direction adjacent to the biasing direction. It contacts the shoe 12 (surface 125) (FIG. 8).

Therefore, the pressure contact force when the third vane 43 contacts the second shoe 12 on the opposite side to the biasing direction is obtained by subtracting the biasing force of the biasing means 6 from the oil pressure. The force that presses the third vane 43 against the second shoe 12 at the time of regulation is relatively small, and thus the circumferential thickness of the third vane 43 can be small. That is, even if the third vane 43 is provided thin, it can also serve as a stopper. In addition to the urging force of the urging means 6, an oil pressure may act on the first vane 41, but the first vane 41 having the lock mechanism 5 is originally provided thick in the circumferential direction, so that the strength is increased. There is little worry.

(Effect of reference example )
(6) In the variable valve timing mechanism 1 of the internal combustion engine, the rotational force of the crankshaft is transmitted, and the rotational force is transmitted to the housing 10 having the four shoes 11 to 14 convex on the inner peripheral side and the camshaft 3. The same number of vanes 41 to 44 as the shoes 11 to 14 which are provided so as to be relatively rotatable with respect to the housing 10 and relatively rotate between the shoes 11 to 14, and the rotor 40 integrated with the vanes 41 to 44 are provided. And one of the vanes 41 to 44 (first vane 41) is thick in the circumferential direction, and the vane rotor 4 has locking means (lock mechanism 5) capable of restricting the relative rotation, and in the circumferential direction. Oil chambers separated by adjacent shoes 11-14 and rotor 40, advance chambers A1-A4 and retard chambers R1-R4 in which the oil chambers are separated by vanes 41-44, and advance chamber A1 Supply / discharge oil to ~ A4 or retarded chamber R1 ~ R4 Oil passages (branch passages 201 to 204, 211 to 214, etc.) for providing a third vane 43 on the opposite side of the first vane 41 (with locking means) across the axis O of the vane rotor 4 The vanes 41, 42, 44 are connected to the housing 10 between the shoes 11, 13, 14 and the vanes 41, 42, 44 forming the oil chambers A2, A4, A1 "excluding" the rotating oil chamber A3. The urging means 6 (spring units 61, 63, 64) for urging in the direction is provided, and the second shoe 12 and the third shoe 13 on both sides in the circumferential direction of the third vane 43 on the opposite side are disposed on the axis O. The angle formed with respect to the shoes on the both sides in the circumferential direction of the other vanes 41, 42, 44 (the fourth shoe 14 and the first shoe 11, the first shoe 11 and the second shoe 12, the third shoe 13 and the fourth shoe 14 ) Is smaller than the angle formed with respect to the axis O.

Therefore, the same effect as (1) of Example 1 can be obtained, and the effect of improving the weight balance of the mechanism 1 and suppressing vibration during VTC operation is achieved.

(7) The lock means is a lock piston 51 housed in the vane 41 and operates in the axial direction to lock the relative rotation of the housing 10 and the vane rotor 4 or to release the lock.
Therefore, the same effect as (3) of Example 1 can be acquired.

(8) The urging means 6 is a coil spring, and one coil spring 610, 630, 640 is housed in each advance chamber A2, A4, A1.
Therefore, the same effect as (4) of Example 1 can be acquired.

(9) The vanes 41 and 43 for restricting the relative rotation of the housing 10 and the vane rotor 4 by coming into contact with the shoe are separately provided according to the relative rotation direction.
Therefore, the strength and rigidity that each of the vanes 41 and 43 must have in order to restrict the relative rotation can be reduced.

(10) The vane for restricting the relative rotation includes the first vane 41 having the lock mechanism 5 and the third vane 43 on the opposite side, and the first vane 41 is on the biasing direction side of the biasing means 6. The third vane 43 is in contact with the adjacent first shoe 11, and the third vane 43 is in contact with the adjacent second shoe 12 on the side opposite to the urging direction.
Therefore, the same effect as the above (9) can be obtained, and the thickness of the third vane 43 in the circumferential direction can be small, and there is little worry about strength.

(11) The angle formed between the fourth shoe 14 and the first shoe 11 on both sides in the circumferential direction of the first vane 41 having the lock mechanism 5 with respect to the axis O is the shoe on both sides in the circumferential direction of the other vanes 42 to 44 ( The first shoe 11 and the second shoe 12, the second shoe 12 and the third shoe 13, the third shoe 13 and the fourth shoe 14) are made larger than the angle formed with respect to the axis O.
Therefore, the weight balance of the mechanism 1 can be improved, and vibration during VTC operation can be suppressed.

(12) In addition, it is good also as providing the radial direction length of the 3rd vane 43 on the opposite side to the 1st vane 41 smaller than the other vanes 41,42,44.
That is, since the third vane 43 has neither the urging means 5 nor the lock mechanism 5, the radial length of the third vane 43 can be shortened within a range in which strength can be maintained against contact with the second shoe 12. Is possible. By shortening the radial length of the third vane 43, the vane rotor 4 can be reduced in weight, and the volume of the oil chambers A3 and R3 can be adjusted to reduce the amount of oil necessary for relative rotation. it can.

[Other embodiments]
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to this embodiment and does not depart from the gist of the present invention. Any changes in the design of the range are included in the present invention.

For example, in the first embodiment, the VTC (mechanism 1) of the present invention is installed only on the exhaust side camshaft of the engine. However, it may be installed on the intake side camshaft, both on the exhaust side and on the intake side. VTC may be applied to Further, the rotation of the crankshaft may be directly transmitted to both camshafts by the rotation transmission member, or after being transmitted to one camshaft, the rotation is separately transmitted to the other camshaft by the rotation transmission member. There is no particular limitation.

It is assumed that provided in Example 1 biasing means 6 (spring unit) to the advance chamber, may be provided to the retard chamber. This is because, depending on the type in which the rotation of the crankshaft is transmitted to the camshaft, it may be necessary to bias the retarded side.

In Example 1, although the most advanced side locking position of the vane rotor at the time of engine stop (restart time), not limited to this, which the initial position of the VTC and locked in a predetermined position suitable for engine start It is good to do. In the first embodiment, the lock piston that is engaged and disengaged by hydraulic pressure is used as the lock unit. However, for example, a clutch mechanism, a lever mechanism, or the like may be used. In addition, if the initial position of the vane rotor suitable for starting the engine is set to the most advanced angle side (or the most retarded angle side), the vane rotor can be completely maintained if the vane rotor can be held at the initial position when the engine is stopped (restarted). There is no need to lock, and it may be held on the most advanced angle side (or the most retarded angle side) using an urging means (spring unit) without providing a locking means.

Although it was decided coil spring provided in the spring unit in the first embodiment is one, may be more than two, not particularly limited.

Was used coil springs in the spring unit in the first embodiment, it may be an elastic member such as a leaf spring instead of the coil spring. In the first embodiment, each spring unit is provided with a holder (holding portion), but the holder (holding portion) may be omitted as appropriate.

In the first embodiment, we decided to use the timing chain as a member for transmitting power from the crankshaft is engine driven shaft to the housing 10 of the mechanism 1, it is also possible to use a belt or a gear. As the member on the side of the housing 10 to which the rotation is transmitted, a pulley driven by a belt, a gear driven by gears, or the like can be used in addition to a sprocket.

In Example 1, the sprockets has a configuration that also serves as a member (rear plate) closing the camshaft side of the housing, the rotation transmitting member may be provided anywhere in the housing, the opposite side (front and camshaft It is good also as providing in the outer periphery of a plate side) or a housing (main-body part).

In the first embodiment has formed the female screw for fastening the bolt b1~b4 the rear plate 103, the female screw provided in the front plate 101, front plate 101, body portion 102, and a rear plate 103, a bolt B1 to b4 may be integrally tightened and fixed from the X axis positive direction side.

Although the four the number of vanes in the first embodiment, may be another number is not particularly limited.

In Example 1, the relative rotation in the biasing direction of the biasing means 6, it is assumed that regulates the contact of the first vane 41 and the first shoe 11, the other vane and the shoe, i.e. the second vane 42 The second shoe 12, the third vane 43 and the third shoe 13, and the fourth vane 44 and the fourth shoe 14 may be regulated by contact with one or a plurality of sets.

FIG. 3 is a cross-sectional view of the variable valve timing mechanism according to the first embodiment (B-O-B cross section in FIG. 2A). (A) Sectional drawing (AA sectional view of FIG. 1) of the variable valve timing mechanism in the most advanced angle position of Example 1, (b) It is the elements on larger scale. FIG. 3 is a cross-sectional view of the variable valve timing mechanism at the most retarded angle position according to the first exemplary embodiment (a cross section taken along line AA in FIG. 1). FIG. 3 is a partially exploded perspective view of the variable valve timing mechanism according to the first embodiment. FIG. 2 shows a locking mechanism when the engine is stopped according to the first embodiment (partial cross-sectional view taken along the line CC in FIG. 2). FIG. 2 shows a locking mechanism during engine rotation according to the first embodiment (partial cross-sectional view taken along the line CC in FIG. 2). It is sectional drawing (AA sectional view of FIG. 1) of the variable valve timing mechanism in the most advanced angle position of a reference example . It is sectional drawing (the AA cross section of FIG. 1) of the variable valve timing mechanism in the most retarded angle position of a reference example .

1 variable valve timing mechanism 3 camshaft 10 housing 11-14 shoe 4 vane rotor 40 rotor 41-44 vane 5 locking mechanism (locking means)
6 Biasing means 61-63 Spring units 201-204 Branch passage (oil passage)
A1-A4 Advance angle chamber R1-R4 Delay angle chamber

Claims (6)

In a variable valve timing mechanism of an internal combustion engine,
A housing having a plurality of convex shoes on the inner peripheral side, to which the rotational force of the crankshaft is transmitted;
And transmitting a rotational force to the cam shaft, mounted for relative rotation between said housing, possess said shoe as many vanes relative rotation between said shoe, said vanes integral rotor, the One of the vanes is formed as a wide vane having a wider width in the circumferential direction than the other vanes, and the other vanes other than the wide vane have a vane rotor formed in the same size in the circumferential direction ;
An oil chamber defined by the shoe and the rotor adjacent to each other in the circumferential direction;
An advance chamber and a retard chamber in which the oil chamber is separated by the vane;
An oil passage for supplying and discharging oil to the advance chamber or retard chamber;
A locking means provided on the wide vane and capable of restricting relative rotation of the housing and the vane rotor;
The vane is urged in one direction with respect to the housing, and when the housing and the vane rotor are relatively rotated in a direction opposite to the direction in which the vane is urged, the housing and the vane rotor come into contact with each other to restrict the relative rotation And a biasing means provided on each of the shoe and the vane except for the shoe and the wide vane. The variable valve timing mechanism of claim 1 ,
The lock means is a lock piston housed in the wide vane, and locks relative rotation between the housing and the vane rotor by operating in an axial direction, or releases the lock. A variable valve timing mechanism characterized by that. The variable valve timing mechanism of claim 1 ,
The biasing means is a coil spring,
The variable valve timing mechanism, wherein one coil spring is housed in each advance chamber or each retard chamber . The variable valve timing mechanism of claim 1 ,
A passage for supplying oil for operating the locking means is formed in the wide vane so as to communicate with an oil chamber whose volume is increased by the urging force of the urging means. Variable valve timing mechanism. The variable valve timing mechanism of claim 1 ,
The variable valve timing mechanism, wherein each of the shoe and the vane is provided in four pieces . The variable valve timing mechanism of claim 1 ,
The variable valve timing mechanism characterized in that the angle formed by the shoes on both sides in the circumferential direction of the wide vane with respect to the axis of the vane rotor is larger than the angle formed by the shoes on both sides in the circumferential direction of the other vane.

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