Device for controlling lubrication of rocker arms of engine with cylinder deactivation function

A device configured for controlling lubrication of rocker arms of an engine with a CDA function, may include valves, wherein the opening/closing state of valves is varied in accordance with an operation state of a vehicle, to which the device is applied, and then, amounts of oil supplied to respective rocker arms are adjusted. Accordingly, the oil pressure and oil pumping capacity of a main gallery may be reduced and then, an enhancement in fuel economy may be achieved. Furthermore, lubrication performance may be secured through an increase in oil supply amount.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2019-0042698, filed on Apr. 11, 2019 in the Korean Intellectual Property Office, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a device configured for controlling lubrication of rocker arms of an engine with a cylinder deactivation (CDA) function, which is configured for achieving an enhancement in fuel economy through variation of an amount of oil supplied to the rocker arms according to whether or not the CDA function is enabled.

Description of Related Art

Rocker arms function to change the direction of force while performing a seesaw motion to open or close an intake valve and an exhaust valve.

For example, such a rocker arm is supported, at an intermediate portion thereof, by a rocker shaft provided at a cylinder head. When one end portion of the rocker arm is lifted upwards, the other end portion of the rocker arm presses an intake valve or an exhaust valve while rotating about the rocker shaft and then, the pressed valve is opened.

Meanwhile, a cam and a valve, which operate in linkage with the rocker arm, are always supplied with oil through oil passages formed at the rocker arm. The amount of oil supplied to the rocker arm is so large as to correspond to about 25% of the total amount of oil.

In connection with this, in the case of a cylinder deactivation (CDA) engine having a CDA function for deactivating operation of some cylinders in accordance with driving conditions, it is unnecessary to supply oil to the deactivated cylinders because the rocker arms of the deactivated cylinders do not move. However, oil is always supplied to all rocker arms, irrespective of whether or not cylinder deactivation is enabled. As a result, an excessive amount of oil is unnecessarily supplied and then, engine power loss occurs, resulting in degradation in fuel economy.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a device configured for controlling lubrication of rocker arms of an engine with a cylinder deactivation (CDA) function, which is configured for achieving an enhancement in fuel economy through variation of an amount of oil supplied to the rocker arms according to whether or not the CDA function is enabled.

In accordance with an aspect of the present invention, the above and other objects may be accomplished by the provision of a device configured for controlling lubrication of rocker arms of an engine with cylinder deactivation including a partition wall mounted in a rocker shaft, to extend in a longitudinal direction of the rocker shaft such that the partition wall divides an internal space of the rocker shaft into a first space and a second space, a shaft oil supply hole formed at the rocker shaft, to communicate with the first space such that the shaft oil supply hole supplies oil supplied from an outside of the rocker shaft, to the first space, a first rocker arm oil supply hole formed at the rocker shaft, to communicate with the first space such that the first rocker arm oil supply hole always supplies oil present in the first space to the rocker arm associated with a cylinder in which the CDA function is disabled, a valve mounted between the first space and the second space, to perform opening or closing operation such that the valve selectively supplies oil present in the first space to the second space in accordance with the opening/closing operation thereof, and a second rocker arm oil supply hole formed at the rocker shaft, to communicate with the second space such that the second rocker arm oil supply hole selectively supplies oil present in the second space to the rocker arm associated with a cylinder in which the CDA function is enabled.

The valve may be mounted at the partition wall.

The valve may be a check valve configured to be opened when an oil pressure of the first space is equal to or greater than a predetermined pressure.

The partition wall may be formed to have a plate shape, and may extend in a longitudinal axis of the rocker shaft such that the first space and the second space are formed at a first side and a second side of the partition wall, respectively.

The first rocker arm oil supply hole may be formed to extend between the first space and the rocker arm of the CDA-disabled cylinder. The second rocker arm oil supply hole may be formed to extend between the second space and the rocker arm of the CDA-enabled cylinder.

In accordance with the above-described configurations, the opening/closing state of the valves may be varied in accordance with an operation state of the vehicle and then, the amount of oil supplied to the rocker arms of the deactivated cylinders and the amount of oil supplied to the rocker arms of the activated cylinders may be adjusted.

Accordingly, in an engine operation range unnecessary to supply a large amount of oil, the amount of supplied oil may be reduced, reducing the oil pressure and oil pumping capacity of the main gallery. As a result, engine power loss may be reduced, achieving an enhancement in fuel economy. Furthermore, in an engine operation range requiring a large amount of oil for lubrication, the amount of supplied oil may be increased, securing lubrication performance. As a result, durability of elements may be secured.

DETAILED DESCRIPTION

Hereinafter, a configuration of a valve system, to which an exemplary embodiment of the present invention is applied, will be described with reference toFIG. 1. Referring toFIG. 1, a roller pin3is rotatably mounted to one end portion of a rocker arm1. A cam5is in contact with the roller pin3at an external peripheral surface thereof. Accordingly, the rocker arm1rotates in a seesaw manner in accordance with rotation of the cam5. Thus, valve timing, lift and duration are determined in accordance with a cam profile of the cam5.

A screw7is fixedly fitted, at an intermediate portion thereof, in the other end portion of the rocker arm1. A valve bridge9is supported by a lower end portion of the screw7. An intake valve or an exhaust valve (hereinafter, collectively referred to as a “valve”) is mounted at a lower end portion of the valve bridge9such that the valve is opened when pressed by the valve bridge9.

A valve spring is provided at each valve such that the valve spring surrounds the valve. The valve is returned to an original position thereof by elastic recovery force of the valve spring and then, is closed.

Meanwhile, in an exemplary embodiment of the present invention, when oil is supplied from a main gallery27to a rocker shaft11(FIG. 2andFIG. 3), the oil supplied to the rocker shaft11is supplied to the rocker arm1, and is then transferred to the cam5and each valve via oil passages formed at the rocker arm.

In connection with this, it is necessary to vary the amount of oil supplied from the rocker shaft11to the rocker arm1in accordance with driving conditions of a vehicle, to which the valve system is applied, to prevent supply of oil from being unnecessarily excessive.

To the present end, various aspects of the present invention are directed to providing a configuration including a partition wall13, shaft oil supply holes21, first rocker arm oil supply holes23, valves19and second rocker arm oil supply holes25, which are provided within the rocker shaft11.

Referring toFIG. 2andFIG. 3, rocker arms1are fitted around the rocker shaft11. The partition wall13extends in a longitudinal direction within the rocker shaft11and then, the internal space of the rocker shaft11includes a first space15and a second space17.

The shaft oil supply holes21are formed at the rocker shaft11to communicate with the first space15and then, supplies, to the first space15, oil supplied from the main gallery mounted at the outside of the rocker shaft11.

Meanwhile, the first rocker arm oil supply holes23are formed to communicate with the first space15to always supply oil present in the first space15to the rocker arms1associated with cylinders having no cylinder deactivation (CDA) function.

The valves19are mounted between the first space15and the second space17, to perform opening/closing operation. In accordance with opening/closing operation of the valves19, oil present in the first space15is selectively supplied to the second space17.

In the instant case, each valve19may be mounted at the partition wall13. Each valve19may be a check valve configured to be opened when the pressure of oil present in the first space15is equal to or greater than a predetermined pressure.

Of course, the check valve is only an example of the valve. As the valve, a valve opened or closed under control of a controller may be employed in place of the check valve. In the instant case, driving conditions of an engine in the vehicle may be input to the controller and then, the controller may control opening/closing of the valve through determination of a load range of the vehicle or a cylinder deactivation state.

In addition, the term “controller” refers to a hardware device including a memory and a processor configured to execute one or more steps interpreted as an algorithm structure. The memory stores algorithm steps, and the processor executes the algorithm steps to perform one or more processes of a method in accordance with various exemplary embodiments of the present invention.

Meanwhile, the second rocker arm oil supply holes25are formed to communicate with the second space17to selectively supply the rocker arms1associated with cylinders having a CDA function.

That is, when the valves19are opened, oil present in the first space15is supplied to the second space17and then, is supplied to the rocker arms1associated with the second rocker arm oil supply holes25. However, when the valves19are closed, oil present in the first space15cannot be supplied to the second space17. As a result, oil cannot be supplied to the rocker arms1through the second rocker arm oil supply holes25.

For example, a plurality of rocker arms1may be mounted for each cylinder to transmit cam motion to intake and exhaust valves of the cylinder. Assuming that, in the case of a 4-cylinder engine, a CDA function is enabled in a cylinder #1 and a cylinder #2 while being disabled in a cylinder #3 and a cylinder #4, oil present in the first space15may be always supplied to the rocker arms1which transmit cam motion to the intake and exhaust valves of the cylinders #3 and #4.

On the other hand, oil present in the second space17may be selectively supplied to the rocker arms1of the cylinders #1 and #2, in which a CDA function is enabled.

Here, the CDA function is a well-known technology and then, no detailed description will be given of a configuration for deactivating cylinders through a CDA function and an operation principle thereof.

In accordance with the above-described configuration, whether or not cylinder deactivation may be performed is controlled in accordance with an operation range of the vehicle. When some cylinders are deactivated in a low load range, the oil pressure of the first space15is relatively low even though the first space15is filled with oil. In the instant case, the oil pressure of the first space15is lower than an opening pressure of the check valves and then, the check valves are closed.

As a result, oil cannot be introduced into the second space17and then, oil cannot be supplied to the rocker arms1of the deactivated cylinders connected to the second space17, whereas oil present in the first space15may be supplied to the rocker arms1of the cylinders operating normally.

On the other hand, in a high load range, all cylinders operate without presence of any deactivated cylinder and then, the oil pressure of the first space15is relatively high as the first space15is filled with oil. Since the oil pressure of the first space15is higher than the opening pressure of the check valves and then, the check valves are opened.

As a result, oil may be supplied to the rocker arms1of all cylinders connected not only to the first space15, but also to the second space17.

Referring toFIG. 3,FIG. 4, andFIG. 5, the partition wall13is formed to have a plate shape, and extends in a longitudinal axis of the rocker shaft11such that the first space15and the second space17may be formed at a first side and a second side of the partition wall13.

For example, the first space15may be formed under the partition wall13, and the second space17may be formed above the partition wall13.

Meanwhile, each first rocker arm oil supply hole23may be formed to extend between the first space15and the rocker arm1of a corresponding one of the CDA-disabled cylinders.

That is, each first rocker arm oil supply hole23has one end portion connected to the first space15and the other end portion formed to extend toward the rocker arm1of the corresponding CDA-disabled cylinder.

Furthermore, each second rocker arm oil supply hole25may be formed to extend between the second space17and the rocker arm1of a corresponding one of the CDA-enabled cylinders.

That is, each second rocker arm oil supply hole25has one end portion connected to the second space17and the other end portion formed to extend toward the rocker arm1of the corresponding CDA-enabled cylinder.

Hereinafter, oil supply operation in a state in which a CDA function is enabled in accordance with driving of the vehicle in a low load range will be described. In a state in which a CDA function is enabled, cylinders #1 and #2 are activated to operate normally, and cylinders #3 and #4 are deactivated. in the instant state, oil is supplied to the first space15formed under the rocker shaft11through the shaft oil supply holes21.

In the instant case, the first rocker arm oil supply holes23respectively disposed to correspond to the cylinders #1 and #2 are formed to communicate with the first space15, together with the shaft oil supply holes21, and then, oil introduced into the first space15through the shaft oil supply holes21is supplied to the rocker arms1of the cylinders #1 and #2 while being discharged through the first rocker arm oil supply holes23.

However, the second rocker oil supply holes25respectively disposed to correspond to the cylinders #3 and #4 are formed to communicate with the second space17, differently from the shaft oil supply holes21. In the low load range, the pressure of oil supplied to the rocker shaft11is relatively low and then, the check valves are in a closed state. The oil supplied to the first space15through the shaft oil supply holes21cannot be supplied to the second space17. As a result, no oil is supplied to the rocker arms1of the cylinders #3 and #4.

Hereinafter, oil supply operation in a state in which a CDA function is disabled in accordance with driving of the vehicle in a high load range will be described with reference toFIG. 5. In a state in which a CDA function is disabled, not only the cylinder #1 and the cylinder #2, but also the cylinder #3 and the cylinder #4, are activated to operate normally. in the instant state, oil is supplied to the first space15formed under the rocker shaft11through the shaft oil supply holes21.

In the instant case, the first rocker arm oil supply holes23respectively disposed to correspond to the cylinders #1 and #2 are formed to communicate with the first space15, together with the shaft oil supply holes21, and then, oil introduced into the first space15through the shaft oil supply holes21is supplied to the rocker arms1of the cylinders #1 and #2 while being discharged through the first rocker arm oil supply holes23.

Meanwhile, although the second rocker oil supply holes25respectively disposed to correspond to the cylinders #3 and #4 are formed to communicate with the second space17, differently from the shaft oil supply holes21, the pressure of oil supplied to the rocker shaft11is relatively high in the high load range and then, the check valves are in an opened state. Accordingly, the oil supplied to the first space15through the shaft oil supply holes21is supplied to the second space17. As a result, oil is also supplied to the rocker arms1of the cylinders #3 and #4.

As apparent from the above description, the opening/closing state of the valves19is varied in accordance with an operation state of the vehicle and then, the amount of oil supplied to the rocker arms1of the deactivated cylinders and the amount of oil supplied to the rocker arms1of the activated cylinders may be adjusted.

Accordingly, in an engine operation range unnecessary to supply a large amount of oil, the amount of supplied oil may be reduced, reducing the oil pressure and oil pumping capacity of the main gallery. As a result, engine power loss may be reduced, achieving an enhancement in fuel economy.

Furthermore, in an engine operation range requiring a large amount of oil for lubrication, the amount of supplied oil may be increased, securing lubrication performance. As a result, durability of elements may be secured.