Oil drain structure of valve timing adjusting device for internal combustion engine

An oil drain structure of a valve timing adjusting device for an internal combustion engine is provided to adjust a valve timing of at least one of an intake valve and an exhaust valve by a torque of a cam shaft and a pressure of a working fluid. The oil drain structure of the valve timing adjusting device includes a rotation preventing means to suppress a position change between a rotor and a housing by regulating a relative rotation of the rotor with respect to the housing.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of Korean Patent Application No. 10-2016-0001689, filed on Jan. 6, 2016, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to a valve timing adjusting device for an internal combustion engine, and more particularly, to an oil drain structure of a valve timing adjusting device for an internal combustion engine.

BACKGROUND

Generally, an internal combustion engine (hereafter, referred to as an “engine”) is equipped with a valve timing adjustment apparatus that can change timing of intake valves and discharge valves (e.g., exhaust valves), depending on the operation state of the engine. Such a valve timing adjustment apparatus adjusts the timing of intake valves or exhaust valves by changing a phase angle according to the displacement or rotation of the camshaft connected to the crankshaft via a timing belt or chain.

In general, a vane type valve timing adjustment apparatus that includes a rotor having a plurality of vanes freely rotated by working fluid in a housing is generally used.

The vane type valve timing adjustment apparatus adjusts valve timing between a full advance phase angle and a full retard phase angle by using a difference in rotational phase generated due to relative rotation in an advance direction or a retard direction of a rotor that is rotated through vanes operated by the pressure of working fluid supplied to an advance chamber or a retard chamber. In an emergency situation or engine stop condition, the rotation of the cam shaft and crank shaft is synchronized by locking the rotor at a specific position via a locking pin.

We have discovered that a positive torque is generated by friction due to rotation of a cam in opposite direction to the rotational direction of the cam. Meanwhile, a negative torque is generated by restoring force of a valve spring in the same direction as the rotational direction of the cam when a valve starts closing, and the negative force is smaller than the positive torque.

SUMMARY

The present disclosure provides an oil drain structure of a valve timing adjusting device for an internal combustion engine capable of smoothly and certainly performing a phase adjustment or a locking operation to improve reliability and having a simple structure to reduce a design burden and reduce manufacturing costs.

In one form of the present disclosure, there is provided an oil drain structure of a valve timing adjusting device between a crank shaft and a cam shaft of an internal combustion engine, the oil drain structure including: a housing coupled with a ratchet plate interlocking with the crank shaft and having an inner space; a rotor configured to partition an inner space of the housing into an advance chamber and a retard chamber while interlocking with the cam shaft, the rotor having a plurality of vanes relatively rotating in the advance chamber and the retard chamber with respect to the housing by the pressure of the working fluid to adjust a phase; and a rotation preventing means configured to suppress a position change between the rotor and the housing by regulating the relative rotation of the rotor with respect to the housing. In particular, the rotation preventing means includes: a locking member elastically installed in a mounting hole of at least one of the vanes; a plurality of locking grooves connected to each other at different depth on a surface of a ratchet plate so that the plurality of locking grooves are coupled with a locking pin member during a locking operation of the locking pin member; a drain groove connected to at least one locking groove of the plurality of locking grooves and configured to discharge the working fluid within the at least one locking groove during the locking operation; and a drain hole formed in the rotor and configured to communicate with the drain groove.

The locking pin member may further include an upper cap configured to close one end portion of the mounting hole.

The locking pin member may include an outer pin elastically installed against the upper cap and an inner pin elastically installed in the outer pin against the upper cap.

The outer pin may have a structure in which an outer circumferential portion of an upper portion thereof is divided into a step-shaped extension and a cylindrical part having a flange part coupled with a lower edge of the step-shaped extension.

The drain hole may be positioned to be adjacent to an inner circumferential surface of the housing at an outside of the mounting hole of the at least one of the vanes.

The drain groove may include a first drain groove extending in a radial direction of the rotor and a second drain groove extending in a circumferential direction of the rotor and being connected to the first drain groove, the second drain groove configured to be selectively blocked from or communicate with the drain hole.

The first and second drain grooves may be positioned to be biased in an advance direction with respect to a central line of the at least one locking groove of the plurality of locking grooves.

The locking pin member may further include a lower cap configured to support an outer circumferential surface of an outer pin, the lower cap positioned at another end portion of the mounting hole.

DETAILED DESCRIPTION

Hereinafter, a valve timing adjusting device for an internal combustion engine, as an exemplary form of the present disclosure, will be described in detail with reference to the accompanying drawings.

FIG. 1is an assembling cross-sectional view of a valve timing adjusting device100in one exemplary form of the present disclosure.

Referring toFIGS. 1 and 2, in the valve timing adjusting device100, a body2connected to a cam shaft1of an internal combustion engine is formed to be extended, a sprocket4that is connected to a crank shaft3by a chain or a timing belt (not illustrated) is rotatably coupled with an outer circumference of the body2, and a disk-shaped ratchet plate5is integrally formed inside of the sprocket4.

The body2interlocking with the cam shaft1makes up a solenoid valve8that switches a flow of working fluid and controls the flow while a spool6having a plurality of oil grooves6aformed on an outer circumferential surface thereof is elastically installed by a spring7and thus selectively communicates with a plurality of oil ports2aformed on an outer circumference of the body2according to a control signal of a controller (not illustrated).

Meanwhile, the body2is coupled with a cylindrical housing10, a rotor20coupled to be relatively rotated within an inner space of the housing10while interlocking with the cam shaft, and a rotation preventing means30regulating a relative rotation of the rotor20with respect to the housing10.

A plurality of protrusions12are protrudedly formed on an inner circumferential surface11of the housing10at a predetermined interval. Upper ends of each protrusion12are formed with sealing grooves13in a length direction of the housing10and thus sealing seals14are each inserted into the sealing grooves13to form spaces15between adjacent protrusions12.

Meanwhile, as illustrated inFIG. 2, in the rotor20, a plurality of vanes22are formed at a boss part21coupled with the body2to protrude toward an inner circumferential surface11of the housing10. Upper ends of each vane12are formed with sealing grooves23in a length direction of the rotor20and thus sealing seals24are each inserted into the sealing grooves23to form the spaces15between the adjacent protrusions12of the housing10.

The space15is partitioned into a retard chamber15ain an arrow B direction (that is, advance direction) that is a rotating direction of the cam shaft1and an advance chamber15bin an arrow A direction (that is, retard direction), with respect to the vane12as illustrated inFIG. 2.

Therefore, the working fluid is selectively supplied to the retard chamber15aand the advance chamber15band thus a torque applied to the vane12adjusts an advance phase while the rotor20rotates in the arrow B direction (advance direction) with respect to the housing10or to the contrary, adjusts a retard phase while the rotor rotates in the arrow A direction (retard direction), thereby adjusting valve timing of an intake valve or an exhaust valve.

Meanwhile, the rotation preventing means30is provided to inhibit or prevent the relative rotation of the rotor20to the housing10.

The rotation preventing means30may be installed at any one of the vanes12as illustrated inFIG. 2. Here, for convenience of explanation, the vane22provided with the rotation preventing means30is denoted by reference numeral22A to be differentiated from other vane22.

As illustrated inFIG. 1, the rotation preventing means30may include a locking pin member40inserted into a mounting hole25formed to penetrate through the vane22A, a plurality of locking grooves50formed on a ratchet plate5to be operated in the locked state or release the locked state while being coupled with the locking pin member40, and drain grooves60connected to the locking grooves50to discharge the working fluid of the locking grooves50.

In one form, a drain hole26is formed at the vane22A so that the drain hole26communicates with the drain groove60. As illustrated inFIG. 2, the drain hole26may be positioned to be adjacent to an inner circumferential surface11of the housing10at the outside of the mounting hole25of the vane22A.

Here, as illustrated inFIG. 1, the locking pin member40includes an upper cap41closing one end portion (left end portion inFIG. 1) of the mounting hole25of the vane22A, a hollow cylindrical outer pin43elastically installed at a lower end portion of the upper cap41by an outer spring42, and an inner pin45elastically installed against the upper cap41by an inner spring44while being slidably coupled with an inside of the outer pin43.

Further, the locking pin member40may additionally include a ring-shaped lower cap46supporting an outer circumferential surface of the outer pin43while being positioned at the other end portion (right end portion inFIG. 1) of the mounting hole25.

Meanwhile, as illustrated inFIGS. 1 and 2, the plurality of locking grooves50formed on the ratchet plate5configuring the rotation preventing means30may be formed to be connected to each other at different diameters and different depths while facing the mounting hole25of the vane22. That is, the locking groove50includes a large diameter groove51and a small diameter groove52, in which the large diameter groove51and the small diameter groove52are connected to each other while forming a stepped part53of which the cross section has a step shape.

Further, as illustrated inFIG. 2, the drain groove60may include a first drain groove61extending in a radial direction of the rotor20while being connected to one side of the locking groove50and a second drain groove62extending in a circumferential direction of the rotor20while being connected to the first drain groove61and being selectively blocked from or communicating with the drain hole26.

The first drain groove61may be formed in one or plural in substantially a vertical direction to the large diameter groove51or the small diameter groove52but the present disclosure is not limited thereto. For example, the first drain groove61may be inclinedly connected to the large diameter groove51or the small diameter groove52.

Further,FIG. 2illustrates that the second drain groove62extends in the circumferential direction of the rotor20while being substantially vertically connected to the first drain groove61but the present disclosure is not limited thereto. That is, the second drain groove62may also be inclinedly connected to the first drain groove61, having a predetermined angle with the first drain groove61.

The first and second drain grooves61and62may be positioned to be biased in the advance direction with respect to the central line of the locking groove50. However, the present disclosure is not limited thereto and the first and second drain grooves61and62may also be positioned to be biased in the retard direction (B direction) with respect to the locking groove50.

Meanwhile, an oil passage22bthrough which the working fluid is supplied from the mounting hole25to a space27around the outer pin43and is discharged is inclinedly formed on the vane22A of the rotor20to penetrate through the vane22A so that the oil passage22bcommunicates with the solenoid valve8.

The drain hole26is communicated to the space27so that the working fluid from the locking groove50is able to be discharged through the oil passage22b.

Next, the operation of the locking structure of the valve timing device according to the exemplary form of the present disclosure will be described.

When the engine is normally operated, the rotor20may adjust the valve timing of the intake valve or the exhaust valve through the cam shaft1while freely performing the phase adjustment operation in the advance direction (direction B) or the retard direction (direction A) with respect to the housing10depending on the torque transferred from the cam shaft1while forming the retard chamber15aand the advance chamber15bat the left and right in the space15between protrusions12adjacent to the vane22A.

FIG. 3Aillustrates the state in which the phase adjustment operation is performed in the state in which the vane22A provided with the locking pin member40is biased toward the retard direction, that is, the advanced chamber15bwith respect to the locking groove50. In this case, the locking pin member40including the outer pin43and the inner pin45is partially over the locking groove50, but the second drain groove62does not communicate with the drain hole26of the vane22A but is blocked and the pressure fluid within the locking groove50is not discharged.

Therefore, the rotor20adjusts the valve timing while freely performing the phase adjustment operation in the advance direction (direction B) or the retard direction (direction A) with respect to the housing10, depending on the torque transferred from the cam shaft1.

The section in which the drain groove60communicates with the drain hole26is occurred during the phase adjustment operation. In this case, if the working fluid is supplied to the space27through the oil passage22b, the locking pin member40is released from the locking groove50and the released state is maintained, and the phase adjustment operation of the rotor20is normally performed smoothly even though the drain groove60communicates with the drain hole26. Meanwhile, the valve timing adjusting device is operated at the preset position without a separate control when the engine starts to improve startability or when the emergency situation of the control impossibility occurs while the engine is driven, the locking pin member40is self-locked without the separate control to inhibit or prevent the relative rotation of the rotor20with respect to the housing10.

For example, if as illustrated inFIG. 3A, the phase adjustment operation is performed in the state in which the vane22A provided with the locking pin member40is biased toward the advance chamber15band then the negative torque is transferred from the cam shaft1, the locking pin members40sequentially rotate in the direction B to enter the locking grooves50to be locked, as illustrated inFIG. 3B.

That is, the drain hole26of the vane22A communicates with the drain groove60while the locking pin members40including the outer pin43and the inner pin45sequentially enter the locking grooves50. Therefore, the pressure fluid within the locking groove50is moved to the space27through the drain groove60and the drain hole26and then discharged to the outside through the oil passage22b, and therefore the locking operation of the locking pin member40is smoothly performed.

Meanwhile, to release the locked state of the rotor20, if the working fluid is introduced into the space27through the oil passage22bformed to penetrate through the vane22A, the outer pin43and the inner pin45move to the upper cap41while compressing the outer spring42and the inner spring44by the pressure of the working fluid. Therefore, the rotor20adjusts the valve timing of the intake valve or the exhaust valve while freely performing the phase adjustment operation in the advance direction (direction B) or the retard direction (direction A) with respect to the housing10, depending on the torque transferred from the cam shaft1.

The section in which the drain groove60communicates with the drain hole26may be occurred during the phase adjustment operation. In this case, if the working fluid is supplied to the space27through the oil passage22bto release the locked state of the locking pin member40and maintain the released state thereof and therefore the phase adjustment operation of the rotor20is normally performed smoothly even though the drain groove60communicates with the drain hole26.

FIG. 3Cillustrates the state in which the phase adjustment operation is performed in the state in which the vane22A provided with the locking pin member40is biased toward the advance direction, that is, the retard chamber15awith respect to the locking groove50. LikeFIG. 3A, though the locking pin member40is partially over the locking groove50, the drain hole26does not communicate with the drain groove60and the pressure fluid within the locking groove50is not discharged.

The rotor20adjusts the valve timing while freely performing the phase adjustment operation in the advance direction (direction B) or the retard direction (direction A) with respect to the housing10, depending on the torque transferred from the cam shaft1.

In one form of the present disclosure as described above, the drain groove60of the ratchet plate5and the drain hole26of the rotor20are blocked at the time of the phase adjustment operation of the locking pin member40and communicate with each other at the time of the locking to discharge the working fluid of the locking groove50to the outside, such that the locking operation of the locking pin member40may be smoothly and certainly performed, thereby improving the reliability and making the structure simple to reduce the design burden of the components and reduce manufacturing costs.

The above description relates to the exemplary forms of the present disclosure and does not limit the present disclosure. It is to be understood by those skilled in the art that the present disclosure may be variously changed and modified without departing from the scope of the present disclosure.

For example, the exemplary form of the present disclosure describes that the rotor20is provided with four vanes22but the number of vanes22may be designed to be selected as three or other numbers depending on the type or the operation characteristics of the engine.

Further, the exemplary form of the present disclosure describes that the vane22A provided with the locking pin member40is one but the rotor20may also be provided with the two vanes22A each provided with the locking pin members40.

Meanwhile, as illustrated inFIG. 4, the outer pin43may be changed to the structure in which the outer circumferential portion of the upper portion thereof is divided into a step-shaped extension43aand a cylindrical part43chaving a flange part43bcoupled with the lower edge of the extension43a, thereby solving the case in which an accumulated tolerance of the components is concentrated on the outer circumferential surface of the outer pin43slid while adhering to the inner circumferential surface of the mounting hole25.

In another form, the drain groove of the ratchet plate and the drain hole of the rotor may perform the blocking function when performing the phase adjustment operation of the locking pin member and discharge the working fluid of the locking groove by communicating with each other at the time of the locking to smoothly and certainly perform the locking operation of the locking pin member, thereby improving the reliability and making the structure simple to reduce the design burden and the manufacturing costs.

Therefore, it should be understood that the above-mentioned forms are not restrictive but are exemplary in all aspects. It is to be understood that the scope of the present disclosure will be defined by the claims rather than the above-mentioned description and all modifications and alternations derived from the claims and their equivalents are included in the scope of the present disclosure.