Variable valve device

A variable valve device includes an outer body that a valve contacts at a side thereof, wherein an end of the other side is supported by a hydraulic lash adjuster, a bearing contacting a cam is formed in the center, and a stepped latching device insertion hole is formed in the center of the other side, an inner body that is located in the outer body, including a side portion that can rotate together with an end portion of the outer body around a valve stem shaft in the same axis, and the other portion is connected to a bearing shaft, a latching device that is inserted in the latching device insertion hole, and that selectively causes movement of the outer body depending on the movement of the inner body, and a lost motion spring that is formed outside of the outer body, and that provides an elastic force to enable the inner body to perform a lost motion.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0123446 filed Dec. 6, 2010, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a variable valve device. More particularly, the present invention relates to a variable valve device that has a variable valve device for two valves operated, and that can easily sense a malfunction of the variable valve device.

2. Description of Related Art

Generally, an internal combustion engine generates power by burning fuel and air input into a combustion chamber. Intake valves are operated by a camshaft, and air is input into the combustion chamber when the intake valves are open.

Also, exhaust valves are operated by the camshaft, and the air is exhausted from the combustion chamber when the exhaust valves are open.

Optimum operation of the intake valves/exhaust valves is changed according to engine speed.

That is, an appropriate lift or an appropriate opening/closing time is changed according to the engine speed.

As described above, in order to realize an appropriate valve operation according to the engine speed, the cams driving the valves are multiply designed, or a variable valve lift (VVL) in which the valves can operate at different lifts according to the engine speed has been researched.

Also, cylinder deactivation (CDA) is a similar concept to the VVL. During CDA, some cylinders are deactivated when braking or running at a predetermined speed, and the fuel supply to the deactivated cylinders and the operation of the intake valves/exhaust valves are stopped.

The VVL apparatus and the CDA apparatus have common ground to adjust valve lifts.

As described above, the optimum intake air and intake speed are varied according to an engine condition. That is, rapid air speed is needed in a low load region, and on the other hand, much intake air is needed in a high load region.

To meet above demanded condition, variable valve lift (VVL) can be adopted in the intake valves.

In that case, the intake air moves fast in a low lift mode, and a high lift mode is applied in a high load region and much air is taken in, so performance, emissions, fuel consumption can be improved.

However, as shown inFIG. 8, which is a perspective view of the conventional VVL apparatus, if a cam22connected to a camshaft20presses a VVL apparatus10, a valve30moves downward. The conventional VVL apparatus has used one VVL apparatus per valve, so two intake VVL apparatuses and two exhaust VVL apparatuses are needed per cylinder.

Because one VVL apparatus operates one valve, only when all the four valves operate normally does the VVL apparatus operate normally. In addition, sensing a malfunction is difficult during a malfunction of one valve, so considerable resources must be invested to sense the malfunction such that the cost is high. Further, the problems are accompanied if only one VVL apparatus per valve is equipped.

SUMMARY OF INVENTION

Various aspects of the present invention provide for a variable valve device having advantages of easily sensing a malfunction of the variable valve device by installing one variable valve device for two valves at an intake valve side and an exhaust valve side, respectively.

Various aspects of the present invention provide for a variable valve device including an outer body that a valve contacts at a side thereof, wherein an end of the other side is supported by a hydraulic lash adjuster, a bearing contacting a cam is formed in the center, and a stepped latching device insertion hole is formed in the center of the other side, an inner body that is located in the outer body, including a side portion that can rotate together with an end portion of the outer body around a valve stem shaft in the same axis, and the other portion is connected to a bearing shaft, a latching device that is inserted in the latching device insertion hole, and that selectively causes movement of the outer body depending on movement of the inner body, and a lost motion spring that is formed outside of the outer body, and that provides an elastic force to enable the inner body to perform a lost motion.

The latching device according to various aspects of the present invention may include a latching pin that is inserted in the latching device insertion hole and is hollow at a portion thereof, a latching spring that is located at the hollow portion of the latching pin and provides the latching pin with elastic force, and a plate that is located at an end portion of the outer body and supports the latching spring.

The movement of the latching pin according to various aspects of the present invention may be limited by a step of the latching device insertion hole.

The lost motion spring according to various aspects of the present invention may have a straight line portion, and an installation groove of the lost motion spring formed at the outer body is formed in a step such that the lost motion spring is stably installed.

A protrusion according to various aspects of the present invention may be formed in the upper portion of the valve stem such that rotation of the valve stem is prevented.

The bearing according to various aspects of the present invention may be combined with the bearing shaft, and the bearing shaft is formed with a fixed diameter or is formed with two steps.

If the bearing shaft according to various aspects of the present invention is formed with a fixed diameter, the bearing shaft may tightly fit at a side of a bearing shaft insertion hole of the inner body, and if the bearing shaft is formed with two steps, the bearing shaft may tightly fit at both sides of the bearing shaft insertion hole of the inner body.

The height of the cam according to various aspects of the present invention may be controlled such that the difference between the valves is in the lamp section of the cam.

As described above, if two intake valves or two exhaust valves malfunction simultaneously when even one variable valve device malfunctions, the malfunction is easily sensed, and the cost can be reduced by installing one variable valve device per two valves.

DETAILED DESCRIPTION

A variable valve device according to various embodiments of the present invention includes an outer body100to which a valve stem500that is connected to a valve by a valve stem shaft540is installed at a side thereof, and hydraulic lash adjusters (HLA)24are respectively installed at both ends of the other side, wherein the outer body100is supported by the HLA24, a bearing320contacting a cam is formed in the center thereof, a latching device insertion hole165is formed in a step in the center of the other side and can rotate around the valve stem shaft540.

The variable valve device according to various embodiments of the present invention also includes an inner body200that is located in the outer body100, an end thereof rotates around the valve stem shaft540together with an end of the outer body100, and the other side is combined with a bearing shaft300.

The variable valve device according to various embodiments of the present invention also includes a latching device600that is inserted in the latching device insertion hole165, and selectively causes movement of the outer body100dependent on the movement of the inner body200.

The variable valve device according to various embodiments of the present invention also includes a lost motion spring400that is respectively formed at both ends of the outer body100, and supplies elastic force to enable the inner body200to perform a lost motion.

The lost motion spring400performs a function such that the inner body200is positioned at an original position by providing the inner body200, which has moved downward during the CDA operation (in latching mode), with elastic force.

Bearing shaft insertion holes135and265and valve stem shaft insertion holes155and255are formed at the outer body100and the inner body200such that the bearing shaft300can be combined with the valve stem shaft540.

The valve stem shaft540plays a role as an axle for the rotation of the inner body200, and is engaged with the valve stem500such that the valve stem shaft540transfers force to a valve, and is engaged with the outer body100by laser welding.

The valve stem500contacting the top end portion of the valve transfers force to the valve and the HLA24supports the CDA device in an opposite position of the valve and functions as an oil passage, and to achieve this, an oil passage151is formed in the outer body100.

The cross-section of the inner body200has a “[” shape, the valve stem shaft insertion hole255and the bearing shaft insertion hole265are respectively formed apart by a predetermined distance at both sides of the paralleled portion in the inner body200, and a latching device insertion hole235is formed at a portion that is vertically intersected with a parallel portion.

The latching device600is inserted into the latching device insertion hole165of the outer body100and the latching device insertion hole235of the inner body200such that movement of the inner body200is subject to movement of the outer body100. The latching device600includes a latching pin620that is partially hollow, a latching spring640that is located at the hollow portion and provides the latching pin620with elastic force, and a plate660that is located at the end of the outer body100and supports the latching spring640.

The latching pin620is formed in a step such that movement of the latching pin620is restricted by the step of the latching device insertion hole165of the outer body100.

FIG. 4is a partially expanded view of a portion “A” ofFIG. 1. The lost motion spring400has been improved in various embodiments of the present invention such that a receiving groove460to which the conventional lost motion spring400is located is formed in a step such that the lost motion spring400does not have a curved line portion and has only a straight line portion410. Therefor, the device is easily manufactured.

That is, the conventional lost motion spring is protruded outward such that a portion from the part draped at the bearing shaft300of the lost motion spring to a spring guide440is somewhat rounded. Therefor, to prepare the spring is somewhat difficult, but the present invention has solved the problem that much force cannot be supported by the curved line portion.

The lost motion spring400can therefor be prevented from deviating by the spring guide440.

Also, a protrusion520is formed at the upper portion of the valve stem500contacting the valve in various embodiments of the present invention such that rotation of the valve stem500can be prevented, and assembling a sliding surface560of the valve stem500in order to face the valve can be easy.

The bearing320directly contacting the cam is engaged with the bearing shaft300, and the bearing shaft300can be formed without steps with one diameter or can be formed with two steps. If the bearing shaft300is formed with a constant diameter, the bearing shaft insertion hole265of the inner body200tightly fits at only one side of the bearing shaft insertion hole265of the inner body200, and if the bearing shaft300is formed with two steps, the bearing shaft300fits so tightly at both sides of the bearing shaft insertion hole265of the inner body200that a deviation of the bearing320due to a deviation of the bearing shaft300can be prevented.

Various embodiments of the present invention relates to a CDA device in which two hydraulic lash adjusters24drive two valves, i.e. an intake valve and an exhaust valve. A difference of the height between the two valves must be in a ramp section of the cam in order to drive the two valves.

To achieve this, the height of the cams must be higher than that of the conventional cams.

The ramp section means a section where the valves30can be smoothly opened/closed, and results from manufacturing tolerance while manufacturing the valves30.

Hereinafter, the operation process according to various embodiments of the present invention will be described.

First,FIG. 2is a cross-sectional view of the CDA device in a latching mode according to various embodiments of the present invention.

The CDA device according to various embodiments of the present invention can have the movement of the inner body200be dependent on the movement of the outer body100by selective oil supply.

Two HLAs24per CDA device are used in various embodiments of the present invention. If there is no problem in a layout of an engine, only one HLA24can be used.

An unlatching mode (CDA on) will be described first.

FIG. 2is a horizontal cross-sectional view of the variable valve device in a latching mode according to various embodiments of the present invention, andFIG. 3is a vertical cross-sectional view of the variable valve device. As shown in theFIG. 2andFIG. 3, when an oil control valve (OCV) is opened, oil from a cylinder head oil gallery flows in through an oil injection hole120, and the inflowed oil exerts pressure on the latching pin620of the CDA device and pushes the latching pin620outward against the latching spring640. By this operation, an unlatching state, in which the inner body200and the outer body100can independently move up and down, is achieved.

By the unlatching mode, although the cam presses the inner body200, the valve maintains a closed state.

A sealing member140is formed such that the supplied oil does not flow out through an oil outlet160.

Also, the latching pin620is formed with two steps, and the end of the latching pin620contacting the inner body200is formed with a similar size to the inner diameter D3of the latching device insertion hole235, but there a step is formed with a larger size D2than the diameter D3at the further inside part.

In the unlatching mode, the descending of the inner body200does not contribute to valve lift even though the cam contacts the bearing320and presses the inner body200, so the CDA mode is fulfilled.

Hereinafter, the latching mode (CDA off) will be described.

The oil control valve is closed in the latching mode, such that the oil from the cylinder head oil gallery is prevented from flowing into the latching pin620of the CDA device. In this way, the latching mode is fulfilled by the latching spring640, so the valves operate when the cam presses the inner body200.

As one CDA device activates two valves in the above way, the CDA device normally operates when the intake/exhaust valves normally operate.

For convenience in explanation and accurate definition in the appended claims, the terms upper, inside, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.