Patent Application
20190153913
This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0154705, filed on Nov. 20, 2017, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a continuous variable valve duration apparatus and an engine provided with the same.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An internal combustion engine generates power by burning fuel mixed with air in a combustion chamber. Intake valves are operated by a camshaft in order to introduce the air, and the air is drawn into the combustion chamber while the intake valves are open. In addition, exhaust valves are operated by the camshaft, and a combustion gas is exhausted from the combustion chamber while the exhaust valves are open.
Optimal operation of the intake valves and the exhaust valves depends on a rotation speed of the engine. That is, an optimal lift or optimal opening/closing timing of the valves depends on the rotation speed of the engine. In order to achieve such optimal valve operation depending on the rotation speed of the engine, various researches, such as designing of a plurality of cams and a continuous variable valve lift (CVVL) that can change valve lift according to engine speed, have been undertaken.
Also, in order to achieve such an optimal valve operation depending on the rotation speed of the engine, research has been undertaken on a continuously variable valve timing (CVVT) apparatus that enables different valve timing operations depending on the engine speed. The general CVVT may change valve timing with a fixed valve opening duration.
However, the general CVVL and CVVT are complicated in construction and are expensive in manufacturing cost.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.
The present disclosure provides a continuous variable valve duration apparatus and an engine provided with the same so as to vary opening duration of a valve based on operation conditions of an engine with a simple construction.
In one form of the present disclosure, a continuous variable valve duration apparatus may include: a camshaft; a cam unit on which a cam is formed, and the camshaft inserted into the cam; an inner wheel configured for transmitting rotation of the camshaft to the cam unit; a wheel housing into which the inner wheel is rotatably inserted and movable perpendicular to the camshaft; a guide shaft on which a guide screw thread is formed and disposed perpendicular to the camshaft; a worm wheel to which an inner screw thread configured for engaging with the guide screw thread is formed therewithin and the worm wheel disposed within the wheel housing; and a control shaft on which a control worm configured for engaging with the worm wheel is formed.
The continuous variable valve duration apparatus according to an exemplary form of the present disclosure may further include a guide bracket to which the guide shaft is mounted.
A fixing hole to which the guide shaft is fixed and a moving space within which the wheel housing is movable may be formed to the guide bracket.
Two guide walls may be formed protruded from the wheel housing and a moving hole in which the guide shaft is inserted may be formed to the each guide wall.
The worm wheel may be disposed between the two guide walls and configured to rotate to selectively push one of the two guide walls to move the wheel housing.
The continuous variable valve duration apparatus may further include a sliding shaft fixed to the guide bracket configured for guiding movement of the wheel housing, and a sliding hole into which the sliding shaft is inserted may be formed to the wheel housing.
The continuous variable valve duration apparatus may further include a worm shaft cap fixed to the guide bracket configured for supporting the control shaft.
A first sliding hole and a second sliding hole may be formed the inner wheel respectively, and a cam slot may be formed to the cam unit. The continuous variable valve duration apparatus may further include a roller wheel connected to the camshaft and rotatably inserted into the first sliding hole, and a roller cam slidably inserted into the cam slot and rotatably inserted into the second sliding hole.
The roller cam may include a roller cam body slidably inserted into the cam slot, a cam head rotatably inserted into the second sliding hole and a protrusion formed for preventing the roller cam from being removed.
The roller wheel may include a wheel body slidably connected to the camshaft and a wheel head rotatably inserted into the first sliding hole.
A camshaft oil hole may be formed within the camshaft along a longitudinal direction thereof, a body oil hole communicated with the camshaft oil hole may be formed to the wheel body of the roller wheel, and an oil groove communicated with the body oil hole may be formed to the wheel head of the roller wheel.
The cam unit may include a first cam portion and a second cam portion which are disposed corresponding to a cylinder and an adjacent cylinder respectively, and the inner wheel may include a first inner wheel and a second inner wheel configured for transmitting a rotation of the camshaft to the first cam portion and the second cam portion respectively.
The first inner wheel and the second inner wheel may be connected rotatable to each other.
The continuous variable valve duration apparatus may further include a bearing disposed within the wheel housing and supporting the first inner wheel and the second inner wheel.
Two cams may be formed to the first cam portion and the second cam portion respectively, and a cam connecting portion may be formed between the two cams. The continuous variable valve duration apparatus may further include a cam cap on which a cam supporting portion configured for supporting the cam connecting portion may be formed.
An engine according to an exemplary form of the present disclosure may be provided with the continuous variable valve duration apparatus.
As described above, a continuous variable valve duration apparatus according to an exemplary form of the present disclosure may vary an opening duration of a valve according to operation conditions of an engine, with a simple construction.
The continuous variable valve duration apparatus according to an exemplary form of the present disclosure may be reduced in size and thus the entire height of a valve train may be reduced.
Since the continuous variable valve duration apparatus may be applied to an existing engine without excessive modification, thus productivity may be enhance and production cost may be reduced.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
In the following detailed description, only certain exemplary forms of the present disclosure have been shown and described, simply by way of illustration.
As those skilled in the art would realize, the described forms may be modified in various different ways, all without departing from the spirit or scope of the present disclosure
A part irrelevant to the description will be omitted to clearly describe the present disclosure, and the same or similar elements will be designated by the same reference numerals throughout the present disclosure.
In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity.
Throughout the present disclosure and the claims, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
An exemplary form of the present disclosure will hereinafter be described in detail with reference to the accompanying drawings.
Referring to
In the drawings, 4 cylinders 211, 212, 213 and 214 are formed in the engine, but it is not limited thereto.
A continuous variable valve duration apparatus according to an exemplary form of the present disclosure includes: a camshaft 30, a cam unit 70 on which a cam 71 is formed and of which the camshaft 30 is inserted thereto, an inner wheel 80 configured for transmitting rotation of the camshaft 30 to the cam unit 70, a wheel housing 90 into which the inner wheel 80 is rotatably inserted and movable perpendicular to the camshaft 30, a guide shaft 132 on which a guide screw thread 130 is formed and disposed perpendicular to the camshaft 30, a worm wheel 50 to which an inner screw thread 52 configured for engaging with the guide screw thread 130 is formed therewithin and the worm wheel 50 disposed within the wheel housing 90 and a control shaft 102 on which a control worm 104 configured for engaging with the worm wheel 50 is formed. The control worm 104 is engaged with an outer screw thread 54 formed outer periphery of the worm wheel 50.
The continuous variable valve duration apparatus further includes a guide bracket 134 to which the guide shaft 132 is mounted.
In this case, a valve duration means opening duration of a valve, that is a duration from valve opening and to valve closing.
The camshaft 30 may be an intake camshaft or an exhaust camshaft.
A fixing hole 137 to which the guide shaft 132 is fixed and a moving space 138 within which the wheel housing is movable is formed to the guide bracket 134.
Two guide walls 92 are formed protruded from the wheel housing 90 and a moving hole 94 in which the guide shaft 132 is inserted is formed to the each guide wall 92.
The worm wheel 50 is disposed between the guide walls 92 and selectively rotates to push the guide wall 92 for the wheel housing 90 to be moved.
The continuous variable valve duration apparatus further includes a sliding shaft 135 fixed to the guide bracket 134 through a hole 135c configured for guiding movement of the wheel housing 90 and a sliding hole 96 into which the sliding shaft 135 is inserted is formed to the wheel housing 90.
The continuous variable valve duration apparatus further includes a worm shaft cap 139 fixed to the guide bracket 134 configured for supporting the control shaft 102. The worm shaft cap 139 may be fixed to the guide bracket 134 through bolts 136.
Connecting scheme of the guide bracket 134, the wheel housing 90 and the worm wheel 50 may simply and minimize layout of the continuous variable valve duration apparatus.
The guide shaft 132 may be mounted to the guide bracket 134 through a hole 132b formed to the guide bracket 134 by inserting a connecting pin 132a.
Also, the sliding shaft 135 may be mounted to the guide bracket 134 through a hole 135b formed to the guide bracket 134 by inserting a connecting pin 135a.
Referring to
The continuous variable valve duration apparatus further includes a roller wheel 60 connected to the camshaft 30 and rotatably inserted into the first sliding hole 86 and a roller cam 82 slidably inserted into the cam slot 74 and rotatabley inserted into the second sliding hole 88.
The roller cam 82 includes a roller cam body 82a slidably inserted into the cam slot 74 and a cam head 82b rotatably inserted into the second sliding hole 88.
A protrusion 82c is formed at the roller cam 82 for preventing the roller cam 82 from being separated from the inner wheel 80 along the longitudinal direction of the camshaft 30.
The roller wheel 60 includes a wheel body 62 slidably connected to the camshaft 30 and a wheel head 64 rotatably inserted into the first sliding hole 86 and the wheel body 62 and the wheel head 64 may be integrally formed.
A camshaft hole 34 is formed to the camshaft 30, the wheel body 62 of the roller wheel 60 is movably inserted into the camshaft hole 34 and the wheel head 64 is rotatably inserted into the first sliding hole 86.
A camshaft oil hole 32 is formed within the camshaft 30 along a longitudinal direction thereof, a body oil hole 66 communicated with the camshaft oil hole 32 is formed to the wheel body 62 of the roller wheel 60 and an oil groove 68 (referring to
Lubricant supplied to the camshaft oil hole 32 may be supplied to the inner wheel 80 through the body oil hole 66, the communicate hole 69 and the oil groove 68.
The cam unit 70 includes a first cam portion 70a and a second cam portion 70b which are disposed corresponding to a cylinder and an adjacent cylinder respectively, for example the first cylinder 201 and the adjacent second cylinder 202 and the inner wheel 80 includes a first inner wheel 80a and a second inner wheel 80b transmitting rotation of the camshaft 30 to the first cam portion 70a and the second cam portion 70b respectively.
The continuous variable valve duration apparatus further includes a bearing 140 disposed within the wheel housing 90 for supporting the first inner wheel 80a and the second inner wheel 80b.
The bearing 140 may be a needle bearing, the first and the second inner wheels 80a and 80b are disposed within one wheel housing 90 and the bearing 140 may rotatably support the first and the second inner wheels 80a and 80b.
Since the first and the second inner wheels 80a and 80b are disposed within one wheel housing 90, element numbers may be reduced, so that productivity and manufacturing economy may be enhanced.
The first inner wheel 80a and the second inner wheel 80b within the wheel housing 90 may be connected rotatable to each other. For example, a first inner wheel connecting portion 84 and a second inner wheel connecting portion 85 are formed to the first inner wheel 80a and the second inner wheel 80b respectively, and the first inner wheel connecting portion 84 and the second inner wheel connecting portion 85 are connected to each other.
In the drawing, the first inner wheel connecting portion 84 and the second inner wheel connecting portion 85 are formed as convex and concave, it is not limited thereto. The first inner wheel 80a and the second inner wheel 80b are connected rotatable to each other with variable connecting structures.
In the case that the first inner wheel 80a and the second inner wheel 80b are connected, looseness or vibration due to manufacturing tolerances of the bearing, the inner wheel, the lifter and so on may be reduced.
Two cams 71 and 72 may be formed on the first and the second cam portions 70a and 70b as a pair and a cam cap connecting portion 76 is formed between the paired cams 71 and 72 of each of the first and second cam portions 70a and 70b.
The cam 71 and 72 rotate and open the valve 200.
The continuously variable valve timing apparatus further includes a cam cap 40 on which a cam supporting portion 46 configured to rotatably support the cam cap connecting portion 76 is formed on the cam cap 40.
As shown in
According to engine operation states, an ECU (engine control unit or electric control unit) transmits control signals to the control portion 100, and then the control motor 120 rotates the control shaft 102.
Then, the control worm 104 rotates the formed outer periphery of the worm wheel 50. And since the inner screw thread 52 formed to the worm wheel 50 is engaged with the guide screw thread 130 and thus the worm wheel 50 moves along the guide screw thread 130.
As shown in
When the relative position of the wheel housing 90 with respect to the camshaft 30 is changed, the relative rotation speed of the cams 71 and 72 with respect to the rotation speed of the camshaft 30 is changed.
While the slider pin 60 is rotated together with the camshaft 30, the pin body 62 is slidable within the camshaft hole 34, the pin head 64 is rotatable within the first sliding hole 86, and the roller cam 82 is rotatably within the second sliding hole 88 and slidable within the cam slot 74. Thus, the relative rotation speed of the cams 71 and 72 with respect to the rotation speed of the camshaft 30 is changed.
When the rotation center of the wheel housing 90 with respect to the camshaft 30 moves to one direction, the rotation speed of the cams 71 and 72 are relatively faster than rotation speed of the camshaft 30 from phase a to phase b and from phase b to phase c, then the rotation speed of the cams 71 and 72 are relatively slower than rotation speed of the camshaft 30 from phase c to phase d and from phase d to phase a as shown in
When the rotation center of the wheel housing 90 with respect to the camshaft 30 moves to the opposite direction, the rotation speed of the cams 71 and 72 are relatively slower than rotation speed of the camshaft 30 from phase a to phase b and from phase b to phase c, then the rotation speed of the cams 71 and 72 are relatively faster than rotation speed of the camshaft 30 from phase c to phase d and from phase d to phase a as shown in
As shown in
Although maximum lift of the valve 200 is constant, however rotation speed of the cam 71 and 72 with respect to the rotation speed of the camshaft 30 is changed according to relative positions of the slider housing 90 so that closing and opening time of the valve 200 is changed. That is, duration of the valve 200 is changed.
According to the relative position of the cam slot 74, mounting angle of the valve 200 and so on, opening and closing time of the valve may be simultaneously changed as shown in
While opening time of the valve 200 is constant, closing time of the valve 200 may be retarded or advanced as shown in
While closing time of the valve 200 is constant, opening time of the valve 200 may be retarded or advanced as shown in
As described above, a continuous variable valve duration apparatus according to an exemplary form of the present disclosure may achieve various valve duration with a simple construction.
The continuous variable valve duration apparatus according to an exemplary form of the present disclosure may be reduced in size and thus the entire height of a valve train may be reduced.
Since the continuous variable valve duration apparatus may be applied to an existing engine without excessive modification, thus productivity may be enhance and production cost may be reduced.
While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms, it is to be understood that the present disclosure is not limited to the disclosed forms. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2017-0154705 | Nov 2017 | KR | national |
