JP2005207432A - Valve timing controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the responsiveness of a valve timing control by always obtaining the smooth rotating action of a vane while securing high seal performance between hydraulic chambers. <P>SOLUTION: A timing sprocket 1 and a camshaft rotatable relative to the timing sprocket 1 are so formed that a vane 3 is normally and reversely rotated by the supply and discharge of a relative hydraulic pressure to and from a spark-advance angle side hydraulic chamber 32 and the spark-retard angle side hydraulic chamber 33 in a housing to convert a relative rotation phase between the timing sprocket and the camshaft so as to make variable the opening/closing timings of an intake valve. Dry film coats 50 and 51 for coating are formed on the front end face 3a of the vane in slidable contact with the inner peripheral surface 7a of a front cover 7 to reduce a sliding frictional resistance by the dry film coats 50 and 51 and seal between both hydraulic chambers 32 and 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a so-called vane type valve timing control device that makes opening / closing timings of an intake valve and an exhaust valve of an internal combustion engine variable according to an operating state.

  As a conventional valve timing control device, a vane type device described in Patent Document 1 below is known.

Briefly, in this valve timing control device, the vane fixed to the end of the camshaft is rotatably housed in the cylindrical housing of the timing pulley whose opening end is closed by the front cover and the rear cover. And an advance side hydraulic chamber and a retard side hydraulic pressure between two substantially trapezoidal partition walls projecting inward from the diameter direction on the inner peripheral surface of the housing and the two vane parts of the vane. A room is defined. Then, the hydraulic pressure is supplied to and discharged from the advance side and retard side hydraulic chambers according to the engine operating state, and the vane is rotated forward and backward to change the relative rotational phase of the timing pulley and the camshaft. The intake valve opening and closing timing is made variable.
JP-A-8-121124

  However, according to the conventional valve timing control device, in order to prevent leakage of hydraulic oil between the advance side hydraulic chamber and the retard side hydraulic chamber, for example, the sliding between the vane and the front cover and the rear cover is performed. The moving gap is set very small. Therefore, the sliding frictional resistance between the vane and each cover increases, and smooth rotation of the vane may be hindered. As a result, there is a risk that control accuracy with high valve timing according to changes in the engine operating state cannot be obtained.

  Further, in this conventional example, in order to prevent the leakage of hydraulic oil between both hydraulic chambers as described above, the width length on the base side of the vane and the width length on the tip side of each partition wall portion are defined. ing. That is, the shortest distance of each vane that seals between the retard angle side hydraulic chamber and the advance angle side hydraulic chamber, and between the different retard angle side hydraulic chamber and the advance angle side hydraulic chamber at both axial end surfaces, By setting the side hydraulic chamber and the advance side hydraulic chamber, and between the different retard side hydraulic chamber and the advance side hydraulic chamber to be almost equal to the shortest distance of each partition wall portion sealed at both end faces in the axial direction, Oil leakage between the hydraulic chambers passing between the vane and the front cover and the rear cover is prevented.

  For this reason, the width of the vane and the width of the partition wall are inevitably set to be large.As a result, the number of vane blades and the phase conversion angle between the timing pulley and the camshaft are naturally limited. This makes it difficult to increase the number of vane blades to three or more. Therefore, the response of phase conversion due to the rotation of the vane is likely to be reduced due to the restriction on the number of blades, and the valve timing control range is restricted due to the restriction of the phase conversion angle, so that the engine performance is sufficiently exhibited. Can not be made.

  And since the sliding contact area of the outer peripheral surface of one blade | wing part of a vane and the inner peripheral surface of a housing becomes large, there exists a possibility that a friction resistance may become further larger between both.

  The present invention has been devised in view of the technical problem of the conventional apparatus, and the invention according to claim 1 is a rotating body that is driven to rotate by a crankshaft of an engine, and is rotatable relative to the rotating body. A camshaft, a vane fixed to the end of the camshaft and integrally formed with a plurality of blades on the outer peripheral side of an annular base, a housing that rotatably accommodates the vane, A plurality of partition walls projecting inwardly on an inner peripheral surface, a seal member provided on each of the blades and pressed outward so as to be in sliding contact with the inner peripheral surface of the housing, and the partition walls; The retard-side hydraulic chamber and the advance-side hydraulic chamber defined between both side surfaces of each of the blade portions, and the hydraulic pressure for rotating the vane forward and backward by supplying and discharging the hydraulic pressure relative to both the hydraulic chambers. In the state where the hydraulic pressure supplied from the circuit and the hydraulic circuit is low, the vane A valve timing control device including a locking mechanism for maintaining the rotational position relative to the housing, and is characterized in that the coated front end face of at least sliding of said vane.

  Therefore, according to the first aspect of the invention, the sealing action between the retard side hydraulic chamber and the advance side hydraulic chamber can be obtained by coating the front end face of the vane.

  1 to 3 show an embodiment of a valve timing control device for an internal combustion engine according to the present invention, which is applied to an intake valve side.

  That is, a timing sprocket 1 that is a rotating body that is rotationally driven by a crankshaft not shown in the figure via a synthetic resin timing chain, and a camshaft 2 that is provided to be rotatable relative to the timing sprocket 1. A vane 3 fixed to the end of the camshaft 2 and rotatably accommodated in the timing sprocket 1, a hydraulic circuit 4 for rotating the vane 3 forward and backward by hydraulic pressure, and the timing sprocket 1 and the vane 3. A lock mechanism 10 that locks the relative rotation at a predetermined position or releases the lock is provided.

  As shown in FIG. 3, the timing sprocket 1 includes a rotating member 5 having a tooth portion 5 a that engages with a timing chain on the outer periphery, and a housing that is disposed in front of the rotating member 5 and rotatably accommodates the vane 3. 6, a disc-shaped front cover 7 that is a lid that closes the front end opening of the housing 6, and a substantially disc-like shape that is disposed between the housing 6 and the rotating member 5 and closes the rear end opening of the housing 6. The rotating member 5, the housing 6, the front cover 7, and the rear cover 8 are integrally coupled from the axial direction by four small diameter bolts 9.

  The rotating member 5 has a substantially annular shape, and has four female screw holes 5b through which the small-diameter bolts 9 are screwed in the circumferentially equidistant positions of about 90 ° in the front-rear direction. A step-diameter fitting hole 11 into which a passage-forming sleeve 25 described later is fitted is formed through. Further, a disc-like fitting groove 12 into which the rear cover 8 is fitted is formed on the front end surface.

  The housing 6 has a cylindrical shape with openings at the front and rear ends, and four partition wall portions 13 project from the circumferential position of the inner peripheral surface at 90 °. The partition wall 13 has a trapezoidal shape in cross section, is provided along the axial direction of the housing 6, and both end edges are flush with the both end edges of the housing 6. Four bolt insertion holes 14 through which the small-diameter bolts 9 are inserted are formed penetrating in the axial direction. Further, a U-shaped seal member 15 and a leaf spring 16 that presses the seal member 15 inward are fitted and held in a holding groove 13a that is cut out along the axial direction at the center position of the inner end face of each partition wall portion 13. Has been.

  Further, the front cover 7 has a relatively large-diameter bolt insertion hole 17 formed in the center, and four bolt holes 18 formed at positions corresponding to the bolt insertion holes 14 of the housing 6. ing.

  The rear cover 8 has a disc portion 8a fitted and held in the fitting groove 12 of the rotating member 5 on the rear end surface, and a small-diameter annular portion 25a of the sleeve 25 is fitted in the center. A fitting hole 8c is formed, and four bolt holes 19 are similarly formed at positions corresponding to the bolt insertion holes 14.

  The camshaft 2 is rotatably supported at the upper end of the cylinder head 22 via a cam bearing 23, and an unillustrated cam for opening the intake valve via a valve lifter is integrally provided at a predetermined position on the outer peripheral surface. In addition, a flange portion 24 is integrally provided at the front end portion.

  The vane 3 is integrally formed of a sintered alloy material, and is camshafted by a fixing bolt 26 inserted from the axial direction through the sleeve 25 in which the front and rear portions are fitted in the flange portion 24 and the fitting hole 11, respectively. 2 is fixed to the front end portion of the annular base portion 27. The annular base portion 27 has a bolt insertion hole 27a through which the fixing bolt 26 is inserted at the center thereof, and is integrally provided at a circumferential position of 90 ° on the outer peripheral surface of the base portion 27. And four blade portions 28.

  Each of the first to fourth blade portions 28 has a substantially inverted trapezoidal cross section, is disposed between the partition walls 13, and is provided in the holding groove 29 that is axially cut out in the center of each outer peripheral surface. A U-shaped seal member 30 that is in sliding contact with the inner peripheral surface 6a and a leaf spring 31 that presses the seal member 30 outward are fitted and held. Further, four advance-side hydraulic chambers 32 and retard-side hydraulic chambers 33 are formed between both sides of each blade 28 and both sides of each partition 13.

  Further, dry film coats 50 and 51 are coated on the outer surface of the vane 3. Specifically, the dry film coats 50 and 51 are made of a material such as Teflon (registered trademark) or molybdenum disulfide, and the entire front end surface 3a sliding on the inner end surface 7a of the front cover 7 of the vane 3; The inner peripheral surface 6a of the housing 6 and the sliding outer peripheral surface 28a of each blade portion 28 are coated. Further, as shown in FIGS. 4 and 5, the dry film coats 50 and 51 are formed in a dust lattice shape, and a plurality of rectangular concave portions 52 are formed between the lattices.

  The locking mechanism 10 is formed to penetrate through a predetermined position of the rear cover 8 corresponding to the engaging groove 20 and an engaging groove 20 formed at a predetermined position on the outer peripheral side of the fitting groove 12 of the rotating member 5. An engagement hole 21 whose inner peripheral surface is tapered, a sliding hole 35 formed so as to penetrate along the inner axis direction at a substantially central position of the one blade portion 28 corresponding to the engagement hole 21, and the 1 A lock pin 34 slidably provided in the sliding hole 35 of the two blade portions 28, a coil spring 39 that is a spring member elastically mounted on the rear end side of the lock pin 34, and the lock pin 34 The pressure receiving chamber 40 is formed between the moving hole 35 and the pressure receiving chamber 40.

  The lock pin 34 is formed of a steel material, and as shown in FIGS. 1 to 3, an intermediate-diameter main body 34a on the center side and an engaging portion 34b formed in a substantially conical shape on the tip side of the main body 34a. And a stepped large diameter stopper portion 34c formed on the rear end side of the main body 34a, and is mounted between the bottom surface of the inner concave groove 34d of the stopper portion 34c and the inner end surface of the front cover 7. The coil spring 39 is biased in the direction of the engagement hole 21 by the spring force of the coil spring 39, and the outer peripheral surface between the main body 34a and the stopper 34c and the inner peripheral surface of the sliding hole 35. It slides in the direction of coming out of the engagement hole 21 by the hydraulic pressure in the pressure receiving chamber 40 formed therebetween. The pressure receiving chamber 40 communicates with the retard angle side hydraulic chamber 33 through a through hole 36 formed in a side portion of the blade portion 28. Further, the engaging portion 34 b of the lock pin 34 engages with the engaging hole 21 in the rotation position on the maximum retard angle side of the vane 3.

  Further, when the both 34b and 21 are engaged, one blade portion 28 of the four blade portions 28 is brought into contact with the partition wall portion 13 opposed thereto, and the other blade portions 28 and 28 are connected to this. The relative positional relationship between the lock pin 34 and the engagement hole 21 is set so that the opposing partition walls 13 are separated from each other with a small gap s. Here, the minute gap s is determined by the average torque, the sliding friction, and the size of the vane 3. Accordingly, sticking between the other vanes 3 and the partition wall portion 13 is prevented, and the response during rotation can be improved. It is also possible to set all the four blade portions 28 in the separated state.

  The pressure receiving chamber 40 communicates with the retarded hydraulic chamber 33 through the through hole 36, and the lock pin 34 resists the spring force of the coil spring 39 by the hydraulic pressure introduced from the retarded hydraulic chamber 33. The actuator is operated in the left direction in the drawing, that is, in the retracting direction in which the engaging portion 34b is pulled out from the locking hole 21.

  On the other hand, the coil spring 39 is set based on the relationship between the positive and negative alternating fluctuation torque generated in the camshaft 2 and the vane 3 during the operation of the engine and the hydraulic pressure supplied to the pressure receiving chamber 40. That is, when the hydraulic pressure higher than the average value of the maximum peak value of the positive fluctuation torque and the maximum peak value of the negative fluctuation torque is applied to the pressure receiving chamber 40, that is, the spring force of the coil spring 39 is positive or negative from the average value. It is set to a spring force that compresses and deforms only when hydraulic pressure equal to the torque value within the range up to the negative maximum peak value is applied.

  In the figure, reference numeral 60 denotes an air circulation groove through which air flows in and out from the sliding hole 35 when the lock pin 34 moves back and forth.

  The hydraulic circuit 4 supplies and discharges hydraulic pressure to and from the first hydraulic passage 41 that supplies and discharges hydraulic pressure to the advance-side hydraulic chamber 32 and the retard-side hydraulic chamber 33 as shown in FIGS. There are two systems of hydraulic passages, the second hydraulic passage 42, and a supply passage 43 and a drain passage 44 are connected to both the hydraulic passages 41, 42 via a passage switching electromagnetic switching valve 45. Yes. The supply passage 43 is provided with an oil pump 47 that pumps the oil in the oil pan 46, while the downstream end of the drain passage 44 communicates with the oil pan 46.

  The first hydraulic passage 41 is branched from the cylinder head 22 in the head portion 26a through the first passage portion 41a formed in the shaft center of the camshaft 2 and the internal axial direction of the fixing bolt 26. The first oil passage 41b that communicates with the first passage portion 41a, and the first oil formed between the small-diameter outer peripheral surface of the head portion 26a and the inner peripheral surface of the bolt insertion hole 27a in the base portion 27 of the vane 3. The oil chamber 41c communicates with the passage 41b, and four branch passages 41d that are formed substantially radially in the base portion 27 of the vane 3 and communicate with the oil chamber 41c and each advance-side hydraulic chamber 32.

  On the other hand, the second hydraulic passage 42 is formed into a second passage portion 42a formed inside the cylinder head 22 and one side of the camshaft 2 and the inside of the sleeve 25 so as to be bent in a substantially L shape. A second oil passage 42b communicating with the passage portion 42a, four oil passage grooves 42c formed at the outer peripheral side edge of the fitting hole 11 of the rotating member 5 and communicating with the second oil passage 42b, and the periphery of the rear cover 8. The four oil holes 42 d are formed at positions of about 90 ° in the direction and communicate with each oil passage groove 42 c and the retard side hydraulic chamber 33.

  The electromagnetic switching valve 45 is a 4-port 2-position type, and an internal valve body is configured to relatively switch and control the hydraulic passages 41, 42, the supply passage 43, and the drain passage 44, and Switching is performed by a control signal from the controller 48. The controller 48 detects the current operating state based on signals from a crank angle sensor that detects the engine speed and an air flow meter that detects the amount of intake air, and the timing sprocket 1 and the cam based on signals from the crank angle and cam angle sensors. The relative rotation position with respect to the shaft 2 is detected.

  Hereinafter, the operation of the present embodiment will be described. First, at the time of engine start and idling operation, the electromagnetic switching valve 48 to which a control signal is output from the controller 48 causes the supply passage 43 and the second hydraulic passage 42 to communicate with each other, and the drain passage 44 and the first hydraulic passage 41 communicate with each other. Let For this reason, the hydraulic pressure pumped from the oil pump 47 is supplied to the retard-side hydraulic chamber 33 through the second hydraulic passage 42 (oil passage groove 42c → oil hole 42d), while the advanced-side hydraulic chamber 32 has In the same way as when the engine is stopped, the hydraulic pressure is not supplied and the low pressure state is maintained.

  Therefore, the vane 3 is in a state in which each blade portion 28 is in contact with one side surface of each partition wall portion 13 on the advance side hydraulic chamber 32 side, as shown in FIG. Accordingly, the relative rotational position of the timing sprocket 1 and the camshaft 2 is held on one side (retarded side), and the opening / closing timing of the intake valve is controlled to the retarded side. As a result, the combustion efficiency by using the inertial intake air is improved, and the engine rotation can be stabilized and the fuel consumption can be improved.

  On the other hand, since the hydraulic pressure in the retard side hydraulic chamber 33 in this operating state is not yet sufficiently high and is relatively low, the vane 3 is held at the illustrated position, but the lock pin 34 is The spring force of the coil spring 39 overcomes the hydraulic pressure supplied from the through hole 36 to the pressure receiving chamber 40, and the engagement portion 34a maintains the engaged state in the engagement hole 21 of the rear plate 8. Therefore, the vane 3 is stably and surely held at the retarded angle side position, and the fluctuation of the hydraulic pressure in the retarded angle side hydraulic chamber 33 and the occurrence of oscillation vibration due to the positive / negative fluctuation torque generated in the camshaft 2 are generated. This can prevent the collision noise between each blade 28 and the partition wall 13.

  Further, when the vehicle starts running and shifts to a predetermined low rotation / low load region, the electromagnetic switching valve 45 maintains the current operating state, and when the hydraulic pressure in the retarded side hydraulic chamber 33 becomes high, the pressure receiving chamber 40 is also the same. The internal hydraulic pressure also increases, the lock pin 34 moves backward against the spring force while compressing and deforming the coil spring 39, and the engaging portion 34a comes out of the engaging hole 21 to release the engagement. For this reason, the vane 3 is allowed to rotate freely, but since the hydraulic pressure in the retarded-side hydraulic chamber 33 is high, the vane 3 is stably held at the position shown in FIG.

  Thereafter, when the engine shifts to a middle-rotation load range, the electromagnetic switching valve 45 is actuated by a control signal from the controller 48 to connect the supply passage 43 and the first hydraulic passage 41 while the drain passage 44 and the second hydraulic passage. The passage 42 is communicated. Accordingly, the hydraulic pressure in the retarded hydraulic chamber 33 is now returned to the oil pan 46 from the drain passage 44 through the second hydraulic passage 42 and the retarded hydraulic chamber 33 has a low pressure, while the advanced side is increased. The hydraulic pressure is supplied into the hydraulic chamber 32 via the first oil passage 41a → 41b → branch passage 41d and becomes high pressure. For this reason, the vane 3 rotates clockwise from the position shown in FIG. 2 to the maximum until the blades 28 come into contact with the other side surfaces of the partition walls 13 on the opposite side (retarding side hydraulic chamber side). To do.

  Further, at the time of switching from the retard angle side to the advance angle side, the oil pressure in the retard angle side hydraulic chamber 33 is discharged and becomes a low pressure, but as the vane 3 rotates, Since the hydraulic pressure is pressed and the hydraulic pressure is relatively high, the pressure receiving chamber 40 is also maintained at a high hydraulic pressure. Therefore, the lock pin 34 is held in the retracted position against the spring force of the coil spring 39. It is in a state. Therefore, the vane 3 rotates quickly in the direction of the retard side hydraulic chamber 33 without restricting free rotation.

  Therefore, the timing sprocket 1 and the camshaft 2 are relatively rotated to the other side to control the opening / closing timing of the intake valve to the advance side. As a result, the pump loss of the engine is reduced and the output can be improved.

  Further, when the engine shifts to the high engine speed / high load range, the electromagnetic switching valve 45 is operated to connect the supply passage 43, the second hydraulic passage 42, the drain passage 44, and the first hydraulic passage 41 in the same manner as during idling operation. In order to make the advance side hydraulic chamber 32 low and the retard side hydraulic chamber 33 high to communicate with each other, the vane 3 rotates counterclockwise as shown in FIG. 2 is rotated relative to one side, and the opening / closing timing of the intake valve is controlled to the retard side. As a result, the output can be improved by improving the intake charge efficiency.

  When the engine is stopped, the vane 3 rotates in the direction of the advance side hydraulic chamber 32 in order to undergo idling operation and the like, and is brought into the state shown in FIG. 3, and the engaging portion 34 b of the lock pin 34 is driven by the spring force of the coil spring 39. Engage with the engagement hole 21. Even if the engine is stopped without idling, etc., the vane 3 is rotated in the direction of the advance side hydraulic chamber 32 by the fluctuating torque generated in the camshaft 2, and the lock pin 34 is engaged with the engagement hole. 21 is engaged.

  The hydraulic chambers 32 and 33 can also hold the vane 3 at a desired intermediate position by appropriately supplying and discharging the hydraulic pressure according to the operating state of the engine.

  According to the present embodiment, the sliding between the vane 3 and the housing 6 and the front cover 7 is achieved by the dry film coats 50 and 51 coated on the front end surface 3a of the vane 3 and the outer peripheral surface 28a of each blade 28. Dynamic frictional resistance is greatly reduced. Accordingly, the vane 3 can always rotate smoothly, and as a result, the valve timing control response to changes in the engine operating state is improved.

  In addition, since the dry film coats 50 and 51 are arranged in a grid pattern, the hydraulic oil can be stored inside the grid pattern. Therefore, the lubrication performance between the vane 3 and the housing 6 and the front cover 7 is improved by the stored oil, the rotational sliding frictional resistance of the vane 3 is further reduced, and the rotation property of the vane 3 becomes better.

  Further, the presence of the dry film coats 50 and 51 provides a sealing action between the vane 3 and the inner peripheral surface 6a of the housing 6 and the inner end surface 7a of the front cover 7, so that each advance side hydraulic chamber 32 and each retard angle are provided. The leakage of hydraulic fluid between the side hydraulic chambers 33 is prevented.

  The dry film coat 50 can be arranged in a diamond shape or a ribbon shape as shown in FIG. 6, and a plurality of dry film coats 50 are provided along the circumferential direction of the outer peripheral surface 28b of each blade portion 28 as shown in FIG. It is also possible to arrange them in the form of straight strips.

  Furthermore, according to the present embodiment, since the spring force of the coil spring 39 of the lock mechanism 10 is set to a unique set value as described above, the vibration of the vane 3 due to the fluctuating torque at the initial stage of unlocking is suppressed, and the partition wall 13 And the durability of the vane 3 and the like can be improved.

  FIG. 8 shows a second embodiment of the present invention, in which dry film coats 53 and 54 are coated on the outer peripheral surface 27a of the vane 3 base portion 27 and the inner peripheral surface 6a of the housing 6 instead of the blade portion 28. .

  According to this embodiment, the dry film coats 53 and 54 can ensure a smooth sliding property of the vane 3 at all times, and can sufficiently exhibit the sealing function. 16 and the sealing mechanisms 30 and 31 of each blade portion 28 can be eliminated. As a result, the manufacturing work efficiency can be improved and the cost can be reduced.

  The present invention is not limited to the configuration of the above embodiment. For example, the hydraulic pressure supplied to the pressure receiving chamber 40 of the lock mechanism 10 is not from the retard side hydraulic chamber 33 but uses a hydraulic circuit independent of these. It is also possible. The dry film coat can be variously changed in shape. However, the material and the adhesive force must be capable of maintaining the coating state for a long period of time without being easily peeled off from the outer peripheral surface 28a or the like.

The AA sectional view taken on the line of FIG. 2 which shows the 1st Embodiment of this invention. The BB line arrow directional view of FIG. The exploded perspective view of this embodiment. C arrow line view of FIG. The DD sectional view taken on the line of FIG. The C arrow line view of FIG. 2 which shows the other example of a dry film coat. The C arrow line view of FIG. 2 which shows the further different example of a dry film coat. The BB arrow directional view of FIG. 1 which shows the 2nd Embodiment of this invention.

Explanation of symbols

1. Timing sprocket (rotating body)
DESCRIPTION OF SYMBOLS 2 ... Cam shaft 3 ... Vane 3a ... Front end surface 4 ... Hydraulic circuit 6 ... Housing 7 ... Front cover 10 ... Lock mechanism 13 ... Partition part 27 ... Base part 28 ... Blade | wing part 28a ... Outer peripheral surface 32 ... Advance side hydraulic chamber 33 ... Delay side hydraulic chamber 40 ... Pressure receiving chamber 50, 51, 53, 54 ... Dry film coat (lubricant)
52 ... concave portion

Claims (1)

A rotating body that is rotationally driven by the crankshaft of the engine;
A camshaft rotatable relative to the rotating body;
A vane fixed to the end of the camshaft and integrally formed with a plurality of blades on the outer peripheral side of the annular base;
A housing that rotatably accommodates the vane;
A plurality of partition walls projecting inwardly on the inner peripheral surface of the housing;
A seal member provided on each of the blades and pressed outward so as to be in sliding contact with the inner peripheral surface of the housing;
A retard-side hydraulic chamber and an advance-side hydraulic chamber defined between the partition wall and both side surfaces of the blades;
A hydraulic circuit for supplying and discharging hydraulic pressure to and from the hydraulic chambers to rotate the vane forward and backward,
In a state where the hydraulic pressure supplied from the hydraulic circuit is low, a lock mechanism that maintains the rotational position of the vane with respect to the housing;
A valve timing control device comprising:
A valve timing control device for an internal combustion engine, wherein a coating is applied to at least a sliding front end surface of the vane.

Images