JP2010174660A - Variable valve timing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve timing device, preventing contact between a rotation transmission means and a casing. <P>SOLUTION: The variable valve timing device 16 is used for a variable control of a rotational phase of an intake camshaft 9 with respect to a crankshaft 5. The variable valve timing device includes: a driven gear 15 connected to the crankshaft 5 through a driving gear 14 or the like; a casing 21 rotated integrally with the driven gear 15; and a rotor 22 rotated integrally with the intake camshaft 9, housed in the casing 21 to be relatively rotatable with a predetermined angular range, and defining an advance chamber 55 and a retard chamber 56 between the casing 21 and the rotor 22. In an axial direction of the intake camshaft 9, at least an outer peripheral part of the driven gear 15 is spaced apart from the casing 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable valve timing device used for variable control of a rotational phase of a camshaft with respect to a crankshaft.

  In an automobile engine, a variable valve timing device is used to change the valve timing in accordance with the engine speed. A variable valve timing device is provided at one end of a camshaft, a casing that rotates in synchronization with a crankshaft, and a rotor with a vane that is fixed to the camshaft and accommodated in the casing so as to be relatively rotatable with a predetermined angle range. And by appropriately supplying hydraulic oil (engine oil) to the advance angle chamber and the retard angle chamber defined between the rotor and the casing, the rotational phase of the rotor relative to the casing is changed to The rotational phase of the camshaft is changed (for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-329005

  However, in the variable valve timing apparatus described in Patent Document 1, driven members such as sprockets, pulleys, and gears that are coupled to the crankshaft via rotation transmission means such as belts, chains, and gears are formed integrally with the casing. Therefore, it is necessary to protect the casing by providing a flange or the like so that the rotation transmitting means does not contact the casing.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a variable valve timing device capable of preventing contact between a rotation transmission means and a casing.

  In order to solve the above problems, a first aspect of the present invention is a variable valve timing device (16) used for variable control of a rotational phase of a camshaft (intake camshaft 9) with respect to a crankshaft (5). A driven member (driven gear 15) connected to the crankshaft via rotation transmission means (driving gear 14 and the like), a casing (21) rotating integrally with the driven member, and the camshaft. A rotor (22) that rotates integrally and is accommodated in the casing so as to be relatively rotatable with a predetermined angular range, and that defines a hydraulic oil chamber (advance chamber 55, retard chamber 56) between the casing and the casing; In the axial direction of the camshaft, at least the outer peripheral portion of the driven member is separated from the casing.

  According to this configuration, since the outer peripheral portion of the driven member is separated from the casing in the axial direction of the camshaft, rotation transmission means such as a gear, a chain, and a belt that mesh with the driven member can come into contact with the casing. Is prevented.

  In a second aspect based on the first aspect, the casing has a boss portion (45) extending toward the driven member so as to surround the camshaft, and the driven member is It is characterized by being externally fitted to the boss part by press fitting.

  According to this configuration, since the driven member can be integrally fixed to the casing and modularized, the variable valve timing device can be easily attached to the camshaft. Further, since the driven member is directly attached to the casing, the relative positional relationship between the driven member and the casing can be configured with high accuracy.

  According to the above configuration, it is possible to provide a variable valve timing device that can prevent contact between the rotation transmitting means and the casing.

It is a principal part perspective view of the engine which concerns on embodiment. It is sectional drawing which shows the variable valve timing apparatus which concerns on embodiment. FIG. 3 is a sectional view taken along line III-III in FIG. 2.

  Hereinafter, an embodiment in which the present invention is applied to an automobile engine will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a main part of an engine according to an embodiment. The engine 1 shown in FIG. 1 is a DOHC 4-valve type 4-cycle in-line 4-cylinder gasoline engine. A cylinder block 2 of the engine 1 includes four cylinders, and a piston 3 is slidably accommodated in each cylinder. The piston 3 is connected via a connecting rod 4 to a crankshaft 5 that is rotatably supported by the cylinder block 2.

  The cylinder head 6 provided at the upper part of the cylinder block 2 has two intake valves 7 and two exhaust valves 8 for each cylinder, and an intake camshaft 9 and an exhaust camshaft 10 that drive the intake and exhaust valves 7 and 8. Is provided. A crank pulley 11 that rotates integrally with the crankshaft 5 is provided at one end of the crankshaft 5, and a cam pulley 12 that rotates integrally with the exhaust camshaft 10 is provided at one end corresponding to the crank pulley 11 of the exhaust camshaft 10. It has been. An endless and toothed timing belt (cogged belt) 13 is stretched between the crank pulley 11 and the cam pulley 12. The diameter of the cam pulley 12 is set so that the exhaust camshaft 10 makes a half rotation while the crankshaft 5 makes one rotation.

  The exhaust camshaft 10 includes a drive gear 14 that rotates integrally with the exhaust camshaft 10 at a position away from the cam pulley 12 by a predetermined distance, and the intake camshaft 9 has a driven gear (driven member) 15 that meshes with the drive gear 14. A variable valve timing device 16 is provided. The driven gear 15 is connected to the crankshaft 5 through a crank pulley 11, a timing belt 13, a cam pulley 12, an exhaust camshaft 10, and a drive gear 14 as rotation transmission means, and rotates according to the rotation of the crankshaft 5. .

  Further, the engine 1 includes an oil pump 17 at a lower portion thereof. An endless chain 18 is spanned between a drive shaft of the oil pump 17 and a sprocket (not shown) provided on the crankshaft 5, and the oil pump 17 is stored in an oil pan by the rotation of the crankshaft 5. The engine oil is pumped to each part of the engine 1.

  FIG. 2 is a sectional view showing the variable valve timing device 16 according to the embodiment, and FIG. 3 is a sectional view taken along line III-III in FIG. As shown in FIGS. 2 and 3, the variable valve timing device 16 includes a driven gear 15, a casing 21 fixed to the driven gear 15, a rotor housed in the casing 21 and fixed to the intake camshaft 9. 22 as main components. Hereinafter, for convenience of explanation, the side where the variable valve timing device 16 is provided (the left side in FIG. 2) is the front side and the other side (the right side in FIG. 2) is the rear, with the axial direction of the intake camshaft 9 as a reference. This will be described as a side.

  The rotor 22 includes a cylindrical main body 24 having a through hole 23 into which the end 9a of the intake camshaft 9 is fitted at the center, and four vanes 25a projecting radially outward from the outer periphery of the main body 24. , 25b, 25c, and 25d. The vanes 25a to 25d are arranged at an angular interval of about 90 ° in the circumferential direction. The first vane 25a is formed wider than the other second to fourth vanes, and has a through hole 26 extending in the axial direction at a substantially central portion thereof. Hereinafter, the vanes 25a to 25d are collectively referred to as the vane 25.

  A front end 9 a of the intake camshaft 9 has a stepped portion 27 and is reduced in diameter, and a stepped portion 28 that abuts the stepped portion 27 is formed in the through hole 23 of the rotor 22. A key 29 protrudes from the outer periphery of the end 9 a of the intake camshaft 9, and a key groove 30 into which the key 29 is fitted is formed in the through hole 23. A cover plate 31 having a diameter larger than the diameter of the through hole 23 is fastened to the front end surface of the intake camshaft 9 by bolts 32. The rotor 22 is sandwiched between the step portion 27 of the intake camshaft 9 and the cover plate 31, the position of the intake camshaft 9 in the axial direction is fixed, and the key 29 is fitted into the key groove 30. The intake camshaft 9 rotates integrally. Further, a boss portion 33 protrudes toward the rear side at the peripheral portion on the rear side of the through hole 26.

  The casing 21 includes a rear plate 41 disposed on the rear side of the rotor 22, a cylindrical body 42 disposed on the radially outer side of the rotor 22, and a front plate 43 disposed on the front side of the rotor 22, The rotor 22 is surrounded. The rear plate 41, the cylindrical body 42, and the front plate 43 are integrally fastened by bolts 67, and the joint portions of the respective members are liquid-tight.

  The rear plate 41 is a circular plate-like body, and a through hole 44 that fits around the boss portion 33 of the rotor 22 is formed at the center thereof. A boss 45 is formed around the periphery of the through hole 44 and extends toward the tip of the boss 33 and extends rearward along the outer periphery of the intake camshaft 9.

  The boss portion 45 surrounds the intake camshaft 9, and the inner peripheral surface of the boss portion 45 is in sliding contact with the outer peripheral surface of the intake camshaft 9. As a result, the rear plate 41 is rotatably supported by the intake camshaft 9. Further, the through hole 44 is in sliding contact with the boss portion 33 of the rotor 22, so that it can rotate relative to the rotor 22 that rotates integrally with the intake camshaft 9.

  The tip of the boss 45 abuts on a stepped portion 46 projecting from the outer peripheral surface of the intake camshaft 9, and the position of the rear plate 41 in the axial direction is fixed. The rear plate 41 is in a liquid-tight sliding contact with the rotor 22 on the front surface of the rear plate 41 in a state where the boss 45 is in contact with the stepped portion 46.

  At the base end portion of the boss portion 45, a step portion 46 is formed protruding outward in the radial direction over the outer periphery of the boss portion 45. The outer periphery of the stepped portion 46 protrudes to a substantially intermediate position between the outer periphery of the boss portion 45 and the outer periphery of the rear plate 41.

  The cylindrical body 42 has four protrusions 47 protruding inward on the inner peripheral portion, and a recess 48 is formed between the two adjacent protrusions 47. In a state where the rotor 22 is disposed on the cylindrical body 42, each vane 25 is disposed inside the recess 48, the tip of the protrusion 47 is in sliding contact with the outer peripheral surface of the rotor 22, and the tip of the vane 25 is the cylindrical body 42. It is in sliding contact with the inner peripheral surface of. Accordingly, the recess 48 is divided into two in the circumferential direction by the vane 25 to form an advance chamber 55 and a retard chamber 56.

  A groove 47 a along the axial direction is formed on the sliding surface of the protrusion 47 with the rotor 22, and the groove 47 a is a rectangular parallelepiped metal piece urged toward the rotor 22 by a leaf spring 49. A seal 50 is provided. Similarly, a groove 25e along the axial direction is formed on the sliding contact surface of the vane 25 with the cylindrical body 42. The groove 25e has a rectangular parallelepiped shape urged toward the cylindrical body 42 by a leaf spring 49. A seal 50 which is a metal piece is provided. By these seals 50, the advance chamber 55 and the retard chamber 56 are liquid-tightly separated.

  The vane 25 can move within a range that is not restricted by the protrusions 47 arranged on both sides thereof, and the rotor 22 can rotate relative to the cylindrical body 42 within a predetermined angle range. As the vane 25 moves in the recess 48, the sizes of the advance chamber 55 and the retard chamber 56 change. A compression coil spring 57 is disposed between the surface of the vane 25 on the retarding chamber 56 side and the surface of the protrusion 47 on the retarding chamber 56 side, and the vane 25 is biased toward the advance chamber 55 side. . Therefore, in the initial state, the surface of the vane 25 on the advance chamber 55 side and the surface of the protrusion 47 on the advance chamber 55 side are in contact with each other, and the volume of the advance chamber 55 is minimized.

  The front plate 43 is a circular plate-like body, and a through hole 43a is formed at the center. The front plate 43 is fixed to the front end face of the cylindrical body 42 and is in fluid-tight sliding contact with the main body 24 of the rotor 22 and the front end face of the vane 25.

  In an initial state where the volume of the advance chamber 55 is minimized, a recess 58 having a smaller diameter than the through hole 26 is formed at a position corresponding to the through hole 26 of the vane 25a of the rear plate 41. In the through-hole 26, a lock pin 59 having a projection 59a that can be fitted into the recess 58 at one end is slidably accommodated. The lock pin 59 is biased by a compression coil spring 60 provided between the lock pin 59 and the front plate 43, and the protrusion 59 a of the lock pin 59 is fitted in the recess 58 in the initial state. The depth of the recess 58 is larger than the protruding amount of the protrusion 59a, and a space is formed at the bottom of the recess 58 with the protrusion 59a fitted in the recess 58.

  The driven gear 15 is formed in an annular shape with a through hole 61 in the center, and teeth 62 that mesh with the drive gear 14 are formed on the outer periphery thereof. The outer diameter of the driven gear 15 is approximately the same as the outer diameter of the rear plate 41. The driven gear 15 is fixed to the rear plate 41 by fitting the through hole 61 into the boss portion 45 of the rear plate 41 by press fitting. As a result, the rear plate 41 rotates integrally with the driven gear 15.

  The driven gear 15 has a press-fitting depth restricted by the inner peripheral side of the front surface thereof coming into contact with the rear surface of the stepped portion 46, and the outer peripheral portion including the teeth 62 is separated from the rear plate 41. That is, by fitting the driven gear 15 to the boss portion 45, a groove 63 extending in the circumferential direction is formed between the driven gear 15 and the rear plate 41. The depth and width of the groove 63 are determined by the dimensional shape of the step portion 46. In the present embodiment, the bottom of the groove 63 is located approximately in the middle between the outer periphery of the rear plate 41 and the outer periphery of the boss portion 45.

  On the front surface and the rear surface of the driven gear 15, thinned portions (thick stealing portions) 65 and 66 are formed. The front thinned portion 65 is formed such that the surface on the inner side in the radial direction substantially coincides with the bottom of the groove 63.

  Next, an oil passage structure for supplying hydraulic oil (engine oil) to the advance chamber 55 and the retard chamber 56 will be described. As shown in FIG. 2, the intake camshaft 9 includes a journal portion 9 b that is pivotally supported between the cylinder head 6 and the bearing cap 71 on the rear side of the portion where the variable valve timing device 16 is attached. Yes. A first oil passage 72 and a second oil passage 73 communicating with the oil pump 17 are formed in the cylinder head 6, and one end of each of the cylinder head 6 extends to a sliding contact surface with the journal portion 9 b of the intake camshaft 9. . Oil grooves 74 and 75 extending along the outer periphery of the journal portion 9b are formed on the sliding surface of the cylinder head 6 and the bearing cap 71 with the journal portion 9b. The oil groove 74 communicates with the first oil passage 72, and the oil groove 75 communicates with the second oil passage 73.

  An oil control valve (not shown) driven and controlled by an ECU (not shown) is interposed in the first oil path 72 and the second oil path 73. The oil control valve selectively connects one of the first oil passage 72 and the second oil passage 73 to the oil pump 17 to supply engine oil, and at the same time connects the other to the oil pan, Reduce the oil pressure.

  The intake camshaft 9 includes two independent oil passages 76 and 77 extending in the axial direction. The oil passage 76 is connected to the oil groove 74 via an oil passage 78 extending in the radial direction, and the oil passage 77 is connected to the oil groove 75 via an oil passage 79 extending in the radial direction. In addition, the intake camshaft 9 includes oil grooves 81 and 82 that extend in the circumferential direction at portions that contact the boss portion 33 and the main body portion 24 of the rotor 22. The oil groove 81 communicates with the oil passage 76 through an oil passage 83 extending in the radial direction, and the oil groove 82 communicates with the oil passage 77 through an oil passage 84 extending in the radial direction.

  In a portion corresponding to the oil groove 81 in the boss portion 33 of the rotor 22, an oil passage 91 that extends in the radial direction and communicates the inner peripheral surface and the outer peripheral surface has an angular interval of about 90 ° in the circumferential direction. There are four holes. An oil passage 92 that extends in the radial direction and communicates the outer peripheral surface of the main body 24 and the through hole 23 is formed in a portion corresponding to the oil groove 82 in the main body 24 of the rotor 22.

  An oil groove 93 is recessed in the circumferential direction in a portion in contact with the boss portion 33 of the rear plate 41 and corresponding to the oil passage 91. The oil groove 93 reaches the front surface of the rear plate 41. Further, four oil grooves 94 extending radially outward from the oil grooves 93 are formed on the front surface of the rear plate 41 at an angular interval of about 90 ° in the circumferential direction. Each oil groove 94 extends along the surface of the protrusion 47 on the advance chamber 55 side. Further, in the initial state, the oil groove 94 formed along the protrusion 47 that contacts the first vane 25a communicates with the other end of the oil groove 95 communicating with the recess 58 at one end.

  Next, the operation of the variable valve timing device 16 according to the embodiment will be described. In the initial state (retarding phase), the second oil passage 73 is connected to the oil pump 17 by the oil control valve, and the oil groove 75, the oil passage 79, the oil passage 77, the oil passage 84, the oil groove 82, and the oil passage 92 are provided. The engine oil is supplied to the retarding angle chamber 56 via the. Further, the biasing force of the compression coil spring 57 is also applied to the vane 25, so that the volume of the retarding chamber 56 is maximized. In this initial state, the lock pin 59 enters the recess 58, and the rotational phase between the rotor 22 and the casing 21 is fixed.

  When changing from the initial state to the advance phase, the first oil passage 72 is connected to the oil pump 17 by the oil control valve, and the oil groove 74, the oil passage 78, the oil passage 76, the oil passage 83, the oil groove 81, Engine oil is supplied to the advance chamber 55 via the oil passage 91, the oil groove 93, and the oil groove 94. At this time, engine oil is supplied to the recess 58 through the oil groove 95, and the lock pin 59 is pushed back into the through hole 26 against the biasing force of the compression coil spring. As a result, the engagement between the lock pin 59 and the recess 58 is released, and the rotor 22 can rotate relative to the casing 21. By supplying engine oil to the advance chamber 55, the rotor 22 rotates relative to the casing 21 against the urging force of the compression coil spring 57. That is, the rotational phase of the rotor 22 with respect to the casing 21 changes. Thereby, the rotation phase of the intake camshaft 9 with respect to the crankshaft 5 changes to the advance side.

  In the present embodiment, a groove 63 is formed between the driven gear 15 and the rear plate 41, and the teeth 62 arranged on the outer peripheral portion of the driven gear 15 and the rear plate 41 are separated from each other, and therefore mesh with the driven gear 15. Contact between the drive gear 14 and the rear plate 41 can be prevented. Further, the presence of the groove 63 allows the grindstone for grinding the teeth 62 to be accessed by the teeth 62 without contacting the rear plate 41 even after the driven gear 15 is fixed to the casing 21. . That is, the teeth 62 can be ground even after the driven gear 15 is attached to the casing 21. Further, since the lubricating oil is held in the groove 63, the lubricating oil is easily supplied stably to the teeth 62.

  Since the variable valve timing device 16 is supplied as an integrated module including the driven gear 15, the casing 21, and the rotor 22, it can be easily attached to the intake camshaft 9.

  Although the description of the specific embodiment is finished as above, the present invention is not limited to the above embodiment and can be widely modified. For example, although the driven member is a gear in this embodiment, the driven member may be a sprocket, a pulley, or the like.

  5 .... crankshaft, 9 .... intake camshaft (camshaft), 10 .... exhaust camshaft (rotation transmission member), 11 .... crank pulley (rotation transmission member), 12 .... cam pulley (rotation transmission member), 13 .. Timing belt (rotation transmission member), 14.. Drive gear (rotation transmission member), 15 .. Driven gear (drive member), 16 .. Variable valve timing device, 21 .. Casing, 22. , 45 ·· Boss, 55 · · Advance chamber, 56 · · Delay chamber

Claims (2)

A variable valve timing device used for variable control of a rotational phase of a camshaft relative to a crankshaft,
A driven member connected to the crankshaft via rotation transmission means;
A casing that rotates integrally with the driven member;
A rotor that rotates integrally with the camshaft, is rotatably accommodated in the casing with a predetermined angular range, and defines a hydraulic oil chamber between the rotor and the casing;
The variable valve timing apparatus, wherein at least an outer peripheral portion of the driven member is separated from the casing in the axial direction of the camshaft. The casing has a boss portion extending toward the driven member in a form surrounding the camshaft,
The variable valve timing apparatus according to claim 1, wherein the driven member is externally fitted to the boss portion by press fitting.

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