JP5034869B2 - Variable valve timing device - Google Patents

Description

  The present invention relates to a variable valve timing device, and more particularly to a variable valve timing device that varies the opening / closing timing of an intake valve or an exhaust valve of an engine.

  Conventionally, there has been a variable valve timing mechanism (VVT: Variable Valve Timing-intelligent) that changes the opening and closing timing of intake and exhaust valves in the engine as appropriate in order to improve output and emissions. . In this variable valve timing mechanism, for example, a vane member is connected to a camshaft of an engine, and a case that rotates in conjunction with a crankshaft is provided so as to be relatively rotatable with respect to the camshaft. By accommodating, an advance chamber and a retard chamber are provided so as to sandwich the vane member in the rotation direction of the camshaft, and hydraulic control can selectively supply hydraulic oil to the advance chamber and the retard chamber The devices are connected to each other.

  Therefore, by supplying hydraulic oil to the advance chamber or retard chamber by the hydraulic control device, the vane member is moved by the pressure difference generated in each chamber, and the rotational phase of the camshaft relative to the crankshaft of the engine is advanced. The opening / closing timing of the intake valve and the exhaust valve can be changed.

  FIG. 7 is a schematic diagram showing a hydraulic oil supply path of a conventional variable valve timing mechanism (for example, Patent Document 1). In the figure, a cam journal 100 a is formed on the camshaft 100. The cam journal 100 a is rotatably supported between the bearing portion 104 a of the cylinder head 104 and the bearing cap 103. The cam journal 100a is formed with two journal grooves 106 and 107 constituting first and second oil passages extending along the outer periphery thereof. The cylinder head 104 is also formed with a first head oil passage 108 and a second head oil passage 109 for supplying hydraulic oil to the journal grooves 106 and 107 and the cam journal 100a.

  Further, in order to supply hydraulic oil to an advance chamber (not shown) of the VVT controller 130, the camshaft 100 is formed with a first shaft oil passage 111 extending along the center thereof. The first shaft oil passage 111 is in communication with the journal groove 106. On the other hand, a second shaft oil passage 110 extending in parallel with the first shaft oil passage 111 is formed in the camshaft 100 in order to supply hydraulic pressure by hydraulic oil to a retard chamber (not shown) of the VVT controller 130. ing. The second shaft oil passage 110 communicates with the other journal groove 107.

  The hydraulic oil is supplied to the first head oil passage 108 by the OCV 120 and the second head oil passage 109 is opened to the drain, so that the hydraulic pressure advances through the journal groove 106 and the first shaft oil passage 111. It is supplied to a corner chamber (not shown). On the other hand, the hydraulic oil is supplied to the second head oil passage 109 by the OCV 120 and the first head oil passage 108 is opened to the drain, so that the hydraulic pressure is applied to the journal groove 107 and the second shaft oil passage 110. To the retarding chamber (not shown).

JP-A-7-139327

  However, in the prior art, a pair of journal grooves 106 and 107 are formed in the narrow cam journal 100a. For this reason, the seal width (sealability) of the cam journal 100a is insufficient, and there is a problem in that operation unnecessary due to oil leakage (leakage) occurs. Here, it is conceivable to increase the width of the cam journal 100a. However, since the size of the cam journal 100a increases due to the structure of the engine, it is not desirable because of the demand for downsizing the engine.

  FIG. 8 shows the relationship of the VTT phase angle (actual value) to the VVT command value, where (A) shows the behavior of VVT when there is no oil leakage, and (B) shows the VVT when there is oil leakage. It is a figure which shows an example of a behavior. As shown in FIG. 5A, when there is no oil leakage, the VVT phase angle changes linearly. On the other hand, as shown in FIG. 5B, when there is oil leakage, the VVT phase angle change does not become linear, which may cause a VVT malfunction.

  The present invention has been made in view of the above, and an object of the present invention is to provide a variable valve timing device that can reduce malfunction due to oil leakage from a cam journal without increasing the overall length of the engine. To do.

  In order to solve the above-described problems and achieve the object, the present invention includes a phase variable mechanism having first and second hydraulic chambers, and a variable phase of a camshaft with respect to a crankshaft. The first and second hydraulic passages for communicating the first and second hydraulic chambers of the mechanism and the hydraulic control valve for controlling the hydraulic pressure respectively support the camshaft rotatably and the cam In the variable valve timing device formed on the shaft, the first and second oil passages formed on the camshaft and the first and second oil passages formed on the bearing portion respectively communicate with each other. The first and second grooves are formed in the cam journal, and a partition member is provided between the first and second grooves of the cam journal.

  According to a preferred aspect of the present invention, it is desirable that the partition member is a thrust bearing that restricts displacement of the camshaft in the axial direction.

  According to a preferred aspect of the present invention, it is desirable that the partition member is formed integrally with the camshaft or provided separately.

  According to the present invention, the first and second hydraulic chambers having the first and second hydraulic chambers, the phase variable mechanism for changing the phase of the camshaft with respect to the crankshaft, the first and second hydraulic chambers of the phase variable mechanism, In the variable valve timing device in which the first and second oil passages for communicating with the hydraulic control valves for controlling the hydraulic pressure are formed in the bearing portion for rotatably supporting the camshaft and the camshaft, First and second grooves for communicating the first and second oil passages formed in the camshaft with the first and second oil passages formed in the bearing portion are formed in the cam journal. Since the partition member is provided between the first and second grooves of the cam journal, it is possible to reduce malfunction due to oil leakage from the cam journal without increasing the overall length of the engine. Na .

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  1 is a schematic side view of a variable valve timing device according to a first embodiment, FIG. 2 is a schematic cross-sectional view of the variable valve timing device according to the first embodiment, and FIG. 3 is a diagram of the variable valve timing device according to the first embodiment. It is a schematic sectional drawing showing a VVT controller (phase variable mechanism).

  As shown in FIGS. 1 and 2, the variable valve timing device 1 is provided with a plurality of cam lobes 41 on the camshaft 10, and a crankshaft (not shown) that is an engine output shaft is provided at the tip side thereof. A camshaft sprocket 23 that is driven and connected to the camshaft via a timing belt or the like and rotates in synchronization with the crankshaft is mounted so as to be rotatable relative to the camshaft 10. The camshaft sprocket 23 is connected to the camshaft 10 via a VVT controller 40 provided at the tip of the camshaft 10.

  In the camshaft 10, the cam journal 10 a is rotatably supported between the bearing portion 20 a of the cylinder head 20 and the cam cap 30, and axial displacement is restricted by a plurality of thrust bearings 42.

  The cam journal 10a is formed with a pair of first journal grooves 11 and second journal grooves 12 constituting first and second oil passages extending along the outer periphery thereof. The cylinder head 20 is formed with a first head oil passage 21 and a second head oil passage 22 for supplying hydraulic oil to the first and second journal grooves 11 and 12 and the cam journal 10a.

  Further, in order to supply hydraulic oil to the advance chamber (first hydraulic chamber) 56 shown in FIG. 3, the camshaft 10 has a first shaft constituting a first oil passage extending along the side thereof. An oil passage 13 is formed. The first shaft oil passage 13 communicates with the first journal groove 11. On the other hand, the camshaft 10 is provided with a second oil passage extending in parallel with the first shaft oil passage 13 in order to supply hydraulic pressure by the hydraulic oil to the retarding chamber (second hydraulic chamber) 57 shown in FIG. A second shaft oil passage 14 is formed. The second shaft oil passage 14 communicates with the second journal groove 12.

  Grooves 20b and 30b are formed in the bearing portion 20a of the cylinder head 20 and the cam cap 30. An annular partition plate (partition member) 25 provided between the pair of first and second journal grooves 11 and 12 of the cam journal 10a and externally fitted to the cam journal 10a rotates in the grooves 20b and 30b. It is arranged as possible. As the partition plate 25, for example, an O-ring or the like can be suitably used. The axial direction and radial width of the partition plate 25 are smaller than the axial direction and radial width of the grooves 20b, 30a. Thus, by providing the partition plate 25, the seal width of the cam journal 10a is expanded to the width W (see FIG. 1) indicated by the wavy arrow to improve the sealing performance, and the amount of oil leakage from the cam journal 10a is reduced. Reduced.

  Further, the rotor 51 is in close contact with the end of the camshaft 10 and is fixed by fastening bolts 52, so that the camshaft 10 and the rotor 51 can rotate together. A camshaft sprocket 23 is fitted on the outer periphery of the end of the camshaft 10 so as to be relatively rotatable, and a ring cover 53 is provided so as to surround the outer periphery of the rotor 51 so as to contact the end surface of the camshaft sprocket 23. The end opening of the ring cover 53 is closed by a closing plate 54 having a ring shape, and the camshaft procket 23, the ring cover 53, and the closing plate 54 are fixed by fastening bolts 55 and can be rotated integrally. ing.

  Therefore, the camshaft 10 and the rotor 51 can rotate integrally around the axis L of the camshaft 10. The camshaft sprocket 23, the ring cover 53 and the camshaft 10 and the rotor 51 are closed. The plate 54 is relatively rotatable about the same axis L.

  In the VVT controller 40, an advance chamber (first hydraulic chamber) 56 and a retard chamber (second hydraulic chamber) 57 are defined between the camshaft 10 and the rotor 51 and the ring cover 53. The hydraulic pressure is supplied to the advance chamber 56 through the first head oil passage 21, the first journal groove 11, and the first shaft oil passage 13, and the second head oil passage 22, the second journal groove 12. , And the hydraulic pressure is supplied to the retard chamber 57 through the second shaft oil passage 14, so that the rotational phase of the camshaft sprocket 23 and the camshaft 10 is changed, and the rotation of the camshaft 10 relative to the crankshaft (not shown) The phase is changed to the advance side or the retard side, and the opening / closing timing of an unillustrated intake valve or exhaust valve can be changed.

  The first head oil passage 21 and the second head oil passage 22 are connected to an OCV (hydraulic control valve) 60. Further, a supply passage 61 and a discharge passage 62 are connected to the OCV 60, and the supply passage 61 is provided at a lower portion of an engine (not shown) via an oil pump 63 that is driven by rotation of a crankshaft (not shown). The oil pan 64 is connected, and the discharge passage 62 is directly connected to the oil pan 64.

  The OCV 60 has a spool 66 in which four valve portions 65a, 65b, 65c, 65d are formed. The spool 66 is biased in one direction (rightward in FIG. 2) by a coil spring 67. While being supported, it is biased and supported by the electromagnetic solenoid 68 in the other direction (left direction in FIG. 2). In the demagnetized state of the electromagnetic solenoid 68, the spool 66 is biased and supported in one direction by the biasing force of the coil spring 67. At this time, the first head oil passage 21 and the supply passage 61 are communicated with each other. At the same time, the second head oil passage 22 and the discharge passage 62 communicate with each other. Therefore, the hydraulic oil in the oil pan 64 is sent out from the supply passage 61 to the advance chamber 56 by the oil pump 63 and the hydraulic oil in the retard chamber 57 is returned into the oil pan 64 through the discharge passage 62. .

  On the other hand, when the electromagnetic solenoid 68 is excited, the spool 66 is biased and supported in the other direction against the biasing force of the coil spring 67. At this time, the first head oil passage 21 and the discharge passage 62 are Are communicated with each other, and the second head oil passage 22 and the supply passage 61 are communicated with each other. Therefore, the hydraulic oil in the oil pan 64 is sent to the retard chamber 57 by the oil pump 63, and the hydraulic oil in the advance chamber 56 is returned to the oil pan 64 through the discharge passage 62.

  As shown in FIG. 3, the ring cover 53 has four projecting portions 71 a, 71 b, 71 c, 71 d that protrude toward the axis L of the camshaft 10 on the inner peripheral surface 53 a of the ring cover 53. Are formed at predetermined intervals. Grooves 72a, 72a, 72c, 72d are formed at predetermined intervals in the circumferential direction of the ring cover 53 between the projecting portions 71a, 71b, 71c, 71d. The rotor 51 is formed with four vane members 73a, 73b, 73c, and 73d that protrude outward from the outer peripheral surface so as to be inserted into the grooves 72a, 72a, 72c, and 72d. And in each groove part 72a, 72a, 72c, 72d in which each vane member 73a, 73b, 73c, 73d was inserted, it is divided into the advance chamber 56 and the retard chamber 57 by this vane member 73a, 73b, 73c, 73d. Has been. The advance chamber 56 and the retard chamber 57 are positioned so as to sandwich the vane members 73a, 73b, 73c, 73d from both sides in the circumferential direction of the rotor 51.

  Therefore, when the electromagnetic solenoid 68 of the OCV 60 is demagnetized, the hydraulic oil is supplied from the first shaft oil passage 13 to the advance chamber 56 and is operated from the retard chamber 57 via the second shaft oil passage 14. Oil is discharged. As a result, the vane members 73a, 73b, 73c, and 73d move relative to each other in the direction of arrow A in FIG. 3, so that the rotor 51 relatively rotates in the direction of arrow A, thereby the camshaft with respect to the camshaft sprocket 23. 10 is changed, and the opening / closing timing of the intake valve or the exhaust valve is advanced.

  On the other hand, when the electromagnetic solenoid 68 of the OCV 60 is excited, hydraulic oil is supplied from the second shaft oil passage 14 to the retard chamber 57 and is operated from the advance chamber 56 via the first shaft oil passage 13. Oil is discharged. As a result, the vane members 73a, 73b, 73c, and 73d move relative to each other in the direction indicated by the arrow B in FIG. 3, so that the rotor 51 rotates relative to the direction indicated by the arrow B. The relative rotation phase of the camshaft 10 is changed in the opposite direction to that described above, and the opening / closing timing of the intake valve or exhaust valve is retarded.

  Further, when the excitation current is adjusted by controlling the drive current to the electromagnetic solenoid 68, the spool 66 is stopped at an arbitrary position between the position in the demagnetized state and the position in the excited state, and according to the stop position. Thus, the amount of hydraulic oil supplied and discharged from the advance chamber 56 and the retard chamber 57 can be adjusted. Further, by adjusting the supply / discharge amount of the hydraulic oil, the hydraulic oil in the advance chamber 56 and the retard chamber 57 are set to appropriate pressures, respectively, so that the relative rotation phase of the camshaft 10 can be fixed.

  In this case, the drive current to the electromagnetic solenoid 68 is duty-controlled, and the supply of hydraulic oil to the advance chamber 56 and the retard chamber 57 is controlled, thereby changing the opening / closing timing of the intake valve or exhaust valve, It can be fixed at the opening and closing time.

  As described above, according to the first embodiment, the first and second shaft oil passages 13 and 14 formed in the camshaft 10 and the first and second cylinder oil passages formed in the cylinder block 20. First and second journal grooves 11 and 12 for communicating with 21 and 22 are formed in the cam journal 10a, and function as a partition between the first and second journal grooves 11 and 12 of the cam journal 10a. Since the partition plate 25 is provided, the width of the seal surface of the cam journal 10a can be increased, and the malfunction due to oil leakage from the cam journal 10a can be reduced without increasing the overall length of the engine.

  FIG. 4 is a schematic side view of the variable valve timing device according to the second embodiment, and FIG. 5 is a schematic cross-sectional view showing a VVT controller (phase variable mechanism) in the variable valve timing device according to the second embodiment. In the first embodiment, the partition plate 25 is provided as a partition member that partitions the pair of first and second journal grooves 11 and 12, but in the second embodiment, a thrust bearing is provided as the partition member. It is what.

  4 and 5, thrust grooves 20 c and 30 c are formed in the bearing portion 20 a and the cam cap 30 of the cylinder head 20. In the thrust grooves 20c and 30c, an annular thrust bearing 80 provided between the pair of first and second journal grooves 11 and 12 of the cam journal 10a and externally fitted to the cam journal 10a is rotatably engaged. ing. The thrust bearing 80 regulates the axial displacement of the camshaft 10. The axial width of the thrust bearing 80 is slightly smaller than the axial width of the thrust grooves 20c and 30c. Thus, by using the thrust bearing 80 as the partition member, one of the thrust bearings 42 shown in FIGS. 1 and 2 can be eliminated, and the overall length of the engine can be further shortened.

  FIG. 6 is a schematic cross-sectional view of a variable valve timing device according to a modification. In the modification, as shown in FIG. 6, a thrust bearing 90 is integrally formed with the camshaft 10. As described above, the thrust bearing functioning as the partition member may be separated from the camshaft 10 or formed integrally.

  According to the second embodiment, the partition members for partitioning the first and second journal grooves 11 and 12 are the thrust bearings 80 and 90 for restricting the axial displacement of the camshaft 10, so that the cam journal 10a The malfunction due to oil leakage can be reduced, and the overall length of the engine can be further shortened.

  As described above, the variable valve timing device according to the present invention is useful in the case where oil leakage from the cam journal is reduced and malfunction is prevented without increasing the overall length of the engine.

1 is a schematic side view of a variable valve timing device according to a first embodiment. 1 is a schematic cross-sectional view of a variable valve timing device according to a first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a VVT controller (phase variable mechanism) in the variable valve timing device according to the first embodiment. FIG. 6 is a schematic cross-sectional view of a variable valve timing device according to a second embodiment. FIG. 6 is a schematic cross-sectional view illustrating a VVT controller (phase variable mechanism) in a variable valve timing device according to a second embodiment. It is a schematic sectional drawing of the variable valve timing apparatus which concerns on a modification. It is a schematic diagram which shows the hydraulic-oil supply path | route of the conventional variable valve timing mechanism. It is a figure which shows the relationship of the VTT phase angle (actual value) with respect to a VVT command value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable valve timing apparatus 10 Cam shaft 10a Cam journal 11 1st journal groove 12 2nd journal groove 13 1st shaft oil path 14 2nd shaft oil path 20 Cylinder head 20a Bearing part 21 1st head oil path 22 Second head oil passage 23 Camshaft sprocket 25 Partition plate (partition member)
40 VVT controller 41 Cam lobe 42 Thrust bearing 51 Rotor 53 Ring cover (ring member)
56 Advance chamber (first hydraulic chamber)
57 Retarded chamber (second hydraulic chamber)
60 OCV (hydraulic control valve)
63 Oil pump 64 Oil pan 73a, 73b, 73c, 73d Vane member 80, 90 Thrust bearing (partition member)

Claims (2)

The first and second hydraulic chambers having the first and second hydraulic chambers and having a variable phase mechanism for varying the phase of the camshaft with respect to the crankshaft, and the hydraulic control for controlling the hydraulic pressure In the variable valve timing device in which the first and second oil passages for communicating with the respective valves are formed in a bearing portion for rotatably supporting the camshaft and the camshaft,
First and second grooves for communicating the first and second oil passages formed in the camshaft with the first and second oil passages formed in the bearing portion are formed in the cam journal. An annular partition member that is fitted around the cam journal is provided between the first and second grooves of the cam journal ;
The variable valve timing device according to claim 1, wherein the partition member is a thrust bearing that restricts axial displacement of the camshaft . The variable valve timing device according to claim 1 , wherein the partition member is integrally formed with the camshaft or provided separately.

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