JP2009114875A - Hydraulic oil supply device for valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic oil supply device for a valve train capable of inhibiting a leak of hydraulic oil to an outside of a bearing. <P>SOLUTION: A pair of annular grooves 10, 11 are formed on a journal bearing 4, and a pair of inside flanges 14, 15 fitting to the annular grooves 10, 11 in noncontact states are provided on a journal 3. A pair of outside flanges 12, 13 opposing axial direction both end surfaces 4a, 4b of the journal bearing 4 via a first axial clearance Ca are formed on a camshaft 2, and hydraulic oil supply paths 25, 26 are formed so as to pass through the annular groove 10, 11. A relation of sizes of axial clearances Cc, Cd is set to keep the second axial clearance Cd larger than the third axial gap Cc when the camshaft 2 exists at a reference position where the first axial clearances Cb at both sides of the journal bearing 4 are the same with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus for supplying hydraulic oil to an actuator provided in a variable valve mechanism or the like of an internal combustion engine.

  By changing the phase between the cam sprocket and the camshaft with a hydraulic actuator connected to the camshaft end as a variable valve mechanism that changes the valve operating characteristics of the intake valve or exhaust valve of the internal combustion engine, A variable valve mechanism for advancing or retarding the opening / closing timing of the valve has been put into practical use. As a hydraulic oil supply device applied to this type of variable valve mechanism, there is known a device in which a hydraulic oil supply path is provided from a journal bearing to the actuator via the camshaft (for example, Patent Document 1 and 2). In addition, there is Patent Document 3 as a prior art document related to the present invention.

JP 2000-328908 A JP-A-8-12123 Japanese Utility Model Publication No. 3-54203

  A gap necessary for rotation of the camshaft exists between the journal of the camshaft and the journal bearing. Therefore, in the configuration in which hydraulic oil is guided from the journal bearing flow path to the flow path in the camshaft, part of the hydraulic oil flows into the gap between the journal bearing and the journal and operates outside the bearing through the gap. Oil leaks out. In order to suppress the leakage of the hydraulic oil, the gap between the journal bearing and the journal may be narrowed. In this case, it is necessary to increase the processing accuracy of the journal and the bearing.

  An object of the present invention is to provide a hydraulic oil supply device for a variable valve mechanism capable of suppressing leakage of hydraulic oil to the outside of the bearing without increasing machining accuracy.

  The present invention selectively uses the first hydraulic oil supply path and the second hydraulic oil supply path provided from the journal bearing to the actuator via the inside of the camshaft. In the hydraulic oil supply device of the valve mechanism for supplying the valve shaft, a pair of annular grooves is provided in either one of the journal bearing and the journal of the cam shaft at a distance in the axial direction of the cam shaft, A pair of inner flanges that fit in a non-contact state are provided in the pair of annular grooves, respectively, and the cam shaft is opposed to each of both axial end surfaces of the journal bearing via a first axial gap. A pair of outer flanges are formed, and each of the first and second hydraulic oil supply paths is provided so as to pass through the annular groove, and the first axial gaps are not equal to each other. When the camshaft is positioned at the reference position, there is a second axial gap on the outer side in the axial direction of the inner flange arranged in each annular groove, and a third axial gap on the inner side in the axial direction. When hydraulic oil is introduced into the annular grooves, the pressure difference that displaces the camshaft in the direction in which the first axial clearance close to the axial direction with respect to each annular groove is narrowed is the second and third A size relationship between the second and third axial gaps when the camshaft is at the reference position is set so as to occur between the axial gaps (Claim 1).

  According to the hydraulic oil supply device of the present invention, when hydraulic oil is supplied to the actuator from either the first hydraulic oil supply path or the second hydraulic oil supply path, the hydraulic oil supply path is routed. The hydraulic oil flows out into the second and third axial gaps in any one of the annular grooves, and a pressure difference is generated in the second and third axial gaps according to their magnitude relationship. The pressure difference causes the inner flange to be pushed in the axial direction to displace the camshaft, thereby narrowing the first axial gap closer to the annular groove. As a result, leakage of hydraulic fluid to the outside of the bearing through the gap between the journal and the journal bearing is suppressed.

  In one embodiment of the hydraulic oil supply device of the present invention, when the pair of inner flanges are provided in the journal and the cam shaft is at the reference position, the second axial clearance is the third axis. It is larger than the direction gap (claim 2). In this configuration, the pressure in the second axial gap is larger than that in the third axial gap, and the inner flange is pushed inward in the axial direction, thereby narrowing the first axial gap.

  In another aspect of the hydraulic oil supply device of the present invention, when the pair of inner flanges are provided in the journal bearing, and the cam shaft is at the reference position, the third axial clearance is the second. It is larger than the clearance in the axial direction. In this configuration, the pressure in the second axial gap is larger than that in the third axial gap, and the inner flange is pushed inward in the axial direction, thereby narrowing the first axial gap.

  In the hydraulic oil supply device of the present invention, a labyrinth seal may be provided between the annular groove and both end faces of the journal bearing. According to this embodiment, when the cam shaft is displaced due to a pressure difference generated on both sides in the annular groove, the axial clearance is similarly reduced in the labyrinth seal. Thereby, the leakage suppression effect of hydraulic oil can further be improved.

  In the hydraulic oil supply device of the present invention, the first and second hydraulic oil supply paths may include a section extending radially from the outer periphery of the inner flange to the inside of the inner flange. 5). According to this embodiment, since the outer periphery of the inner flange is located in the middle with respect to the second and third axial gaps, an excessive flow rate of hydraulic oil is introduced into the smaller axial gap, resulting in a pressure difference. Can be avoided.

  In the hydraulic oil supply device of the present invention, when the camshaft is in the reference position, the first and second hydraulic oil supply paths are larger of the second and third axial gaps. It may extend via the axial clearance on the side (claim 6). According to this aspect, it is possible to easily ensure the pressure difference in the annular groove by reliably guiding the hydraulic oil from the hydraulic oil supply path to the larger axial gap.

  As described above, according to the hydraulic fluid supply device of the present invention, the camshaft is displaced using the pressure of the hydraulic fluid supplied to the actuator, whereby the outer flange of the camshaft and the end surface of the journal bearing are Since the axial clearance between them is narrowed, the leakage of hydraulic oil to the outside of the bearing can be suppressed without increasing the machining accuracy.

[First embodiment]
FIG. 1 shows a main part of a variable valve mechanism having a hydraulic oil supply device according to a first embodiment of the present invention. The variable valve mechanism 1 includes a cam shaft 2 that drives an intake valve (or an exhaust valve) of an internal combustion engine, and a journal bearing 4 that supports a journal 3 of the cam shaft 2. FIG. 1 shows one end portion of the cam shaft 2 in the axial direction, and a cam lobe or the like is provided in the omitted portion on the right side. An actuator 5 of the variable valve mechanism 1 is provided at the shaft end of the cam shaft 2. A cam sprocket for winding the cam chain is provided on the outer periphery of the actuator 5, but the illustration is omitted here. The actuator 5 drives the cam shaft 2 relative to the cam sprocket in the circumferential direction, thereby changing the phase of the cam shaft 2 relative to the crankshaft of the internal combustion engine to change the opening / closing timing of the intake valve. Such an actuator is well known, and details of its internal structure are omitted.

  The journal bearing 4 has a configuration in which a bearing base 6 and a cam cap 7 formed as a separate part from the bearing base 6 are connected to each other by a fastening member (not shown) such as a bolt. The bearing stand 6 constitutes a part of a cam carrier (or cam housing) for rotatably supporting the cam shaft 2 on the cylinder head. The bearing base 6 and the cam cap 7 are formed with semi-cylindrical bearing surfaces 6a and 7a, respectively. By combining the bearing stand 6 and the cam cap 7, the journal support surface 8 of the journal bearing 4 is formed continuously so that the bearing surfaces 6a and 7a form one cylindrical surface. The journal support surface 8 is in sliding contact with the journal 3 of the camshaft 2. A radial clearance Ca exists between the journal 3 and the journal support surface 8 as much as necessary to smoothly rotate the cam shaft 2. In the figure, the radial gap Ca is exaggerated.

  Two annular grooves 10 and 11 are formed in the journal bearing 4 at a distance in the axial direction. The annular grooves 10 and 11 are provided in the journal support surface 8 so as to open around the cam shaft 2. On the other hand, the camshaft 2 is in a non-contact state within the annular grooves 10 and 11 and the disk-shaped outer flanges 12 and 13 facing the both end faces 4a and 4b of the journal bearing 4 via the first axial gap Cb. The disc-shaped inner flanges 14 and 15 are formed. These flanges 12 to 15 are all coaxial with the journal 3 of the camshaft 2 and have a constant thickness. FIG. 2 shows the relationship between the inner flange 14 and the journal 3.

  As shown in FIG. 3, the axial thickness t of the inner flanges 14, 15 is smaller than the axial width W of the annular grooves 10, 11. Also, the outer diameter d of the inner flanges 14 and 15 is somewhat smaller than the inner diameter D of the annular grooves 10 and 11. Further, in the axial direction of the cam shaft 2, the distance Lx between the centers Xa and Xb of the inner flanges 14 and 15 is smaller than the distance Ly between the centers Ya and Yb of the annular grooves 10 and 11. As a result, when the cam shaft 2 is located at the reference position where the first axial gaps Cb on both sides of the journal bearing 4 are equal to each other, the inner flanges 14 and 15 in the annular grooves 10 and 11 are disposed on the outer sides in the axial direction. A second axial gap Cc is formed, and a third axial gap Cd is formed on the inner side in the same direction. Moreover, when the camshaft 2 is at the reference position, the second axial gap Cc is larger than the third axial gap Cd.

  As shown in FIG. 1, the cam cap 7 is provided with cap internal passages (bearing internal flow) 21 and 22 extending from the outer periphery to the annular grooves 10 and 11, respectively. Hydraulic fluid discharged from a hydraulic pump (not shown) can be selectively supplied to the in-cap channels 21 and 22 via an electromagnetic valve. Further, in-camera passages 23 and 24 are provided inside the camshaft 2. As is apparent from FIG. 2, the in-axis flow paths 23 and 24 are alternately provided at equal intervals along the circumferential direction.

  The in-axis passage 23 opens on the outer periphery of the inner flange 14. As a result, the in-cap channel 21 and the in-axis channel 23 are connected via the annular groove 10 to form the first hydraulic oil supply path 25. On the other hand, one end side of the in-axis flow path 24 opens to the outer periphery of the inner flange 15. As a result, the in-cap channel 22 and the in-axis channel 24 are connected via the annular groove 11 to form the second hydraulic oil supply path 26. The other end sides of the in-shaft channels 23 and 24 communicate with different oil chambers of the actuator 5, respectively. That is, the first and second hydraulic oil supply paths 25 and 26 are provided so as to reach the actuator 5 from the journal bearing 4 via the annular grooves 10 and 11 and the inside of the camshaft 2, and operate. Each of the oil supply paths 25, 26 includes a section extending radially from the outer periphery of the inner flanges 14, 15.

  When hydraulic oil is selectively supplied to the actuator 5 using any one of the hydraulic oil supply paths 25 and 26, the actuator 5 operates and the camshaft 2 is advanced or retarded with respect to the cam sprocket. Displaces relatively in the direction. For example, when hydraulic fluid is supplied from the first hydraulic fluid supply path 25 to the actuator 5, the actuator 5 operates so that the valve opening / closing timing is advanced, and from the second hydraulic fluid supply path 26 to the actuator 5. When hydraulic oil is supplied to the actuator 5, the actuator 5 operates so that the valve opening / closing timing is retarded.

  According to the above configuration, during the operation of the actuator 5, the axial clearance between the end surfaces 4 a and 4 b of the journal bearing 4 and the outer flanges 12 and 13 using the pressure of the hydraulic oil passing through the hydraulic oil supply paths 25 and 26. By narrowing Cb, oil leakage to the outside of the bearing can be suppressed. For example, when the hydraulic fluid is guided to the first hydraulic fluid supply path 25, first, in the process in which the hydraulic fluid flows from the in-cap channel 21 to the in-axis channel 23 through the annular groove 10, Hydraulic fluid flows from the axial gaps Cc, Cd on both sides of the inner flange 14 to the radial gap Ca. At this time, since the outer second axial gap Cc is larger than the inner third axial gap Cd in the annular groove 10, the pressure in the second axial gap Cc is the third axial gap. It rises above that of Cd. The inner flange 14 is pushed inward (arrow A1 direction) by the pressure difference, and the entire camshaft 2 is displaced in the same direction. As a result, the first axial gap Cb close to the annular groove 10, that is, the axial gap Cb between the outer flange 12 and the end face 4 a of the journal bearing 4, is narrowed, and the hydraulic oil to the outside of the bearing is reduced. Leakage is suppressed. On the other hand, when the hydraulic oil is guided to the second hydraulic oil supply path 26, a similar pressure difference is generated between the axial gaps Cc and Cd in the annular groove 11, and the inner flange 15 is inward (in the direction of arrow A2). ), The entire camshaft 2 is displaced in the same direction. As a result, the first axial gap Cb close to the annular groove 11, that is, the axial gap Cb between the outer flange 13 and the end face 4 b of the journal bearing 4 is narrowed, and hydraulic fluid leaks from there. Is suppressed.

  According to this embodiment, the camshaft 2 is displaced using the pressure of the hydraulic oil supplied to the actuator 5 to narrow the axial gap Cb that is a part of the hydraulic oil leakage path. Alternatively, there is an advantage that the effect of suppressing the leakage of hydraulic oil can be obtained without increasing the processing accuracy of the journal bearing 4. Moreover, by enlarging the outer diameters of the outer flanges 12 and 13, the hydraulic oil leakage path can be narrowed over a wide range, thereby easily increasing the effect of suppressing the hydraulic oil leakage. Further, the in-shaft passages 23 and 24 constituting a part of the hydraulic oil supply passages 25 and 26 open to the outer periphery of the inner flanges 14 and 15, and the outer periphery of the inner flanges 14 and 15 is in the second and third axial directions. Since it is located in the middle of the gaps Cc and Cd, the hydraulic oil flowing into the annular grooves 10 and 11 from the in-cap channels 21 and 22 corresponds to the sizes of the second and third axial gaps Cc and Cd. Flow in at a flow rate. Therefore, it is possible to avoid the disadvantage that the hydraulic fluid having an excessive flow rate is guided to the third axial gap Cd on the smaller side and the pressure difference between the gaps Cc and Cd is reduced.

  As shown in FIG. 4, a labyrinth seal 30 may be provided in a region sandwiched between the annular grooves 10 and 11 and the end surfaces 4 a and 4 b of the journal bearing 4. As shown in FIG. 5, the labyrinth seal 30 does not contact a plurality of labyrinth grooves 31 provided on the journal support surface 8 and a plurality of disc-shaped labyrinth protrusions 32 provided on the journal 3 of the camshaft 2. It has a structure combined with each other in the state. The labyrinth groove 31 is an annular groove that goes around the camshaft 2, and its size is sufficiently smaller than that of the annular grooves 10 and 11. The labyrinth protrusion 32 has a disk shape coaxial with the journal 3. With respect to the axial direction of the cam shaft 2, gaps are provided on both sides of the labyrinth protrusion 32 in a range that does not hinder the displacement of the cam shaft 2 in the axial direction due to the pressure difference in the annular groove 10 or 11 described above. .

  According to this example, when the cam shaft 2 is displaced due to the pressure difference between the axial gaps Cc and Cd in the annular groove 10 or 11, the axial gap between the labyrinth groove 31 and the labyrinth protrusion 32 is also the labyrinth protrusion 32. Decrease on either side. As a result, a hydraulic oil leakage suppressing action is generated in the radial gap Ca between the journal 3 and the journal support surface 8, and thereby, the outer flanges 12, 13 and the end surfaces 4 a, 4 b of the journal bearing 4. The leakage suppression effect can be further enhanced by narrowing down the flow rate of the hydraulic oil flowing into the axial gap Cb.

  As is apparent from FIG. 4, the in-axis passages 23, 24 are opened not at the outer periphery of the inner flanges 14, 15 but at positions facing the second axial gap Cc outside the annular grooves 10, 11. You may do it. Even in this case, a pressure difference similar to the above can be generated between the axial gaps Cc and Cd. However, in the example of FIG. 4, since the second axial gap Cc is used as a part of the first and second hydraulic oil supply paths 25 and 26, the hydraulic oil is reliably supplied to the second axial gap Cc. Therefore, the pressure difference in the annular grooves 10 and 11 can be easily ensured.

[Second form]
FIG. 6 shows a hydraulic oil supply apparatus according to the second embodiment of the present invention. In this embodiment, the annular grooves 10 and 11 are provided in the journal 3 of the cam shaft 2, and the inner flanges 14 and 15 are provided on the journal support surface 8 of the journal bearing 4. The magnitude relationship between the axial gaps Cc and Cd on both sides of the inner flanges 14 and 15 in the annular grooves 10 and 11 is opposite to that of the first embodiment, and the inner third axial gap Cd is the second outer side. Is larger than the axial clearance Cc. The in-cap flow paths 21 and 22 open to the outer periphery of the inner flanges 14 and 15. The in-axis passages 23 and 24 open to the larger axial clearance in the annular grooves 10 and 11, that is, the third axial clearance Cd. However, the opening positions of the in-axis flow paths 23 and 24 may be positions facing the inner flanges 14 and 15. Other configurations are the same as those of the first embodiment.

  According to this embodiment, when the hydraulic oil is guided to the first hydraulic oil supply path 25, the pressure in the third axial gap Cd inside the inner flange 14 is higher than the pressure in the second axial gap Cc outside. Due to the pressure difference, the wall surface of the annular groove 10 facing the third axial gap Cd is pushed inward (in the direction of arrow A1), and the entire camshaft 2 is displaced in the same direction. As a result, the first axial gap Cb close to the annular groove 10, that is, the first axial gap Cb between the outer flange 12 and the end face 4 a of the journal bearing 4 is narrowed to operate out of the bearing. Oil leakage is suppressed. On the other hand, when the hydraulic oil is led to the second hydraulic oil supply path 26, a similar pressure difference is generated between the axial gaps Cc and Cd in the annular groove 11, and the third axial direction of the annular groove 11 is reached. The wall surface facing the gap Cd is pushed inward (in the direction of arrow A2), and the entire camshaft 2 is displaced in the same direction. As a result, the first axial gap Cb close to the annular groove 11, that is, the first axial gap Cb between the outer flange 13 and the end surface 4 b of the journal bearing 4 is narrowed, and the hydraulic oil from there Leakage is suppressed. The in-cap flow paths 21 and 22 may be opened not on the outer periphery of the inner flanges 14 and 15 but on the bearing surface 7a of the cam cap 7 and at a position facing the third axial gap Cd. Also in the second embodiment, a labyrinth seal 30 may be added between the journal 3 and the journal support surface 8 as in FIG.

  The present invention is not limited to the form described above, and may be implemented in various forms. For example, in each embodiment, the hydraulic oil supply path may be changed so that the hydraulic oil is guided from the internal flow path of the bearing base 6 into the annular grooves 10 and 11 instead of the in-cap flow paths 21 and 22. The present invention is not limited to a variable valve mechanism that changes the opening / closing timing of an intake valve or an exhaust valve, but may be any type of operation as long as it is configured to supply hydraulic oil from a journal bearing to the actuator via the inside of a camshaft. It can be applied to a valve mechanism. That is, in the present invention, the actuator is not limited to the example provided for changing the valve operating characteristic, and may be provided for other purposes.

The figure which shows the principal part of the variable valve mechanism to which the hydraulic-oil supply apparatus which concerns on a 1st form was applied. The axial direction sectional view of a cam shaft. The figure which shows the positional relationship of an annular groove and an inner side flange. The figure which shows the modification of FIG. The enlarged view of the labyrinth seal of FIG. The figure which shows the principal part of the variable valve mechanism to which the hydraulic-oil supply apparatus which concerns on a 2nd form was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable valve mechanism 2 Cam shaft 3 Journal 4 Journal bearing 4a, 4b End surface of journal bearing 5 Actuator of variable valve mechanism 8 Journal support surface 10, 11 Annular groove 12, 13 Outer flange 14, 15 Inner flange 21, 22 Cap Inner flow path 23, 24 In-axis flow path 25, 26 Hydraulic oil supply path 30 Labyrinth seal 31 Labyrinth groove 32 Labyrinth protrusion Ca Radial gap between journal and journal bearing Cb First axial gap Cc Second axis Directional clearance Cd Third axial clearance

Claims (6)

The operation of supplying hydraulic oil to the actuator by selectively using the first hydraulic oil supply path and the second hydraulic oil supply path provided from the journal bearing to the actuator via the inside of the camshaft. In the hydraulic fluid supply device of the valve mechanism,
One of the journal bearing and the journal of the cam shaft is fitted with a pair of annular grooves at a distance in the axial direction of the cam shaft, and the other is fitted in a non-contact state with each of the pair of annular grooves. A pair of matching inner flanges are provided,
The camshaft is formed with a pair of outer flanges facing each of both axial end faces of the journal bearing via a first axial gap,
Each of the first and second hydraulic oil supply paths is provided so as to pass through the annular groove,
When the camshaft is located at a reference position where the first axial gaps are equal to each other, the second axial gap is located on the axially outer side of the inner flange disposed in each annular groove. There are 3 axial gaps,
When hydraulic oil is introduced into each annular groove, a pressure difference that displaces the cam shaft in a direction in which the first axial gap close to the axial direction is narrower with respect to each annular groove is the second and third. The size relationship between the second and third axial gaps when the camshaft is at the reference position is set so as to occur between the axial gaps of
Hydraulic oil supply device for the valve mechanism.   2. The operation according to claim 1, wherein the second axial gap is larger than the third axial gap when the pair of inner flanges are provided in the journal and the camshaft is in the reference position. Oil supply device.   The third axial gap is larger than the second axial gap when the pair of inner flanges are provided in the journal bearing and the camshaft is in the reference position. Hydraulic oil supply device.   The hydraulic oil supply device according to any one of claims 1 to 3, wherein a labyrinth seal is provided between the annular groove and both end faces of the journal bearing.   5. The hydraulic oil according to claim 1, wherein the first and second hydraulic oil supply paths include a section extending radially from the outer periphery of the inner flange to the inside of the inner flange. Feeding device.   When the camshaft is at the reference position, the first and second hydraulic oil supply paths extend via a larger axial clearance between the second and third axial clearances. The hydraulic oil supply device according to any one of claims 1 to 4.

Images