EGR coolant control system

An EGR coolant control system according to an exemplary embodiment of the present invention may include a coolant exhaust pipe connected with the coolant supply pipe, an EGR coolant supply pipe connected with the coolant supply pipe and the coolant exhaust pipe, a coolant control plate that is disposed in a junction portion of the coolant supply pipe, the coolant exhaust pipe, and the EGR coolant supply pipe, and that controls supply of a coolant, and an actuator controlling the coolant control plate according to in engine rotation speed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2007-0085719 filed in the Korean Intellectual Property Office on Aug. 24, 2007, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates an EGR coolant control system. More particularly, the present invention relates to an EGR coolant control system that may control a flow of coolant which is supplied to an EGR cooling apparatus, an oil cooler, and so on, so that cooling efficiency may be enhanced.

(b) Description of the Related Art

An exhaust gas recirculation (“EGR”) system is provided to a vehicle for reducing noxious exhaust gas.

Generally, NOx is increased in a case where an air ratio of an air-fuel mixture is high, which is necessary for sufficient combustion. Thus, the exhaust gas recirculation system mixes exhaust gas from an engine with the air-fuel mixture, for example at 5-40%, thereby reducing the amount of oxygen in the air-fuel mixture and retarding combustion, and so lessening generation of NOx.

Generally, the temperature of exhaust gas from an engine is very high, and so a cooling apparatus for cooling recirculation exhaust gas is provided therewith.

An oil cooler, a radiator, and so on need cooling in an operation of a vehicle, and, generally, the flow rate of the required coolant for cooling is increased in proportion to rotation speed of an engine.

The coolant flow rate for cooling the EGR cooling apparatus, the oil cooler, and so on is supplied in proportion to rotation speed of an engine.

As shown inFIG. 1, as the coolant rate is increased, the slope of EGR cooler efficiency is gradually decreased.

That is, when the coolant is simultaneously supplied to the EGR cooling apparatus and the oil cooler in proportion to rotation speed of an engine, the coolant is excessively supplied to the EGR cooling apparatus at a high speed and the coolant is insufficiently supplied to the oil cooler at a high speed. Thus, cooling efficiency is deteriorated.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide an EGR coolant control system that may control an amount of a coolant that is supplied to an EGR cooling apparatus, an oil cooler, and so on according to an engine rotation speed.

An EGR cooling system according to exemplary embodiment of the present invention may reduce a required amount of coolant so that total weight of a vehicle may be reduced.

An EGR cooling system according to exemplary embodiment of the present invention may include a coolant exhaust pipe connected with a coolant supply pipe, an EGR coolant supply pipe connected with the coolant supply pipe and the coolant exhaust pipe, a coolant control plate that is disposed in a junction portion of the coolant supply pipe, the coolant exhaust pipe, and the EGR coolant supply pipe, wherein the coolant control plate controls supply of a coolant, and an actuator controls the coolant control plate according to an engine rotation speed.

The actuator may include a body, a pressure supply pipe for supplying pressure to the body, a diaphragm disposed at one side of the body, and an elastic member for supporting the diaphragm.

The pressure supply pipe may be connected with an intake manifold, and receives back pressure of the intake manifold.

The pressure supply pipe is connected with an exhaust manifold and receives back pressure of the exhaust manifold.

The pressure supply pipe is connected with a input portion of the coolant supply pipe and receives a partial pressure of the coolant supply pipe.

An EGR cooling system according to exemplary embodiment of the present invention may control an amount of a coolant that is supplied to an EGR cooling apparatus, an oil cooler, and so on according to an engine rotation speed.

An EGR cooling system according to exemplary embodiment of the present invention may reduce a maximum required amount of a coolant so that total weight of a vehicle may be reduced.

The above features and advantages of the present invention will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated in and form a part of this specification, and the following Detailed Description of the Invention, which together serve to explain by way of example the principles of the present invention.

DESCRIPTION OF REFERENCE NUMERALS INDICATING PRIMARY ELEMENTS IN THE DRAWINGS

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 2is a perspective view of an EGR coolant control system according to an exemplary embodiment of the present invention.

Referring toFIG. 2, an EGR coolant control system according to an exemplary embodiment of the present invention includes a coolant control portion100and an actuator200.

The coolant control portion100includes a coolant supply pipe110, a coolant exhaust pipe120connected with the coolant supply pipe110, and an EGR coolant supply pipe130connected with the coolant supply pipe110and the coolant exhaust pipe120. That is, the coolant exhaust pipe120and an EGR coolant supply pipe130are branched from the coolant supply pipe110in common.

The coolant exhaust pipe120supplies a coolant to an oil cooler (not shown) or so on, and the EGR coolant supply pipe130supplies a coolant to an EGR cooling apparatus (not shown).

A coolant control plate300is disposed at a junction of the coolant supply pipe110, the coolant exhaust pipe120and the EGR coolant supply pipe130in the coolant control portion100for control of coolant supply to the coolant exhaust pipe120and the EGR coolant supply pipe130.

The actuator200is connected to the coolant control plate300for controlling rotational movement of the coolant control plate300according to rotation speed of an engine (not shown).

The actuator200includes a body220, a pressure supply pipe210for supplying a pressure to the body220, a diaphragm230disposed at and enclosing the other side of the body220to fluidly communicate with the pressure supply pipe210, and an elastic member240disposed between the body220and the diaphragm230for supporting the diaphragm230, a rod250wherein one end of rod250is connected to the diaphragm230and the other end of the rod250hingedly controls the rotation of the coolant control plate300. Both ends of the elastic member240may be coupled to the body220and the diaphragm230respectively.

In detail, the diaphragm230is connected to a proximate end of a rod250and a distal end of the rod250is hingedly connected to a proximate end of rotating shaft260. The proximate end of the rotating shaft260pivotally rotates with respect to a distal end of the rotating shaft260. Furthermore, the distal end of the rotating shaft260is pivotally connected to a portion of the coolant control plate300.

FIG. 3is a cross-sectional view showing an operation of the EGR coolant control system according to an exemplary embodiment of the present invention.

As shown inFIG. 3, the coolant control plate300is controlled according to a rotation speed of an engine, and an amount of coolant supply to the coolant exhaust pipe120and the EGR coolant supply pipe130is controlled by operation of the coolant control plate300.

Hereinafter, an operation of the actuator will be explained.

An exemplary embodiment in which the pressure supply pipe210is connected with an exhaust manifold280will be explained.

Normally, the coolant control plate300is positioned at the home position when the rotation speed of an engine (not shown) is zero.

When the rotation speed of an engine (not shown) is increased to a high speed and thus pressure applied to the diaphragm230of the actuator200is increased, the diaphragm230pushes the rod250to the right direction and the elastic member240extends as shown inFIG. 3. Accordingly the coolant control plate300rotates clockwise from the home position in this embodiment.

As a result, the coolant amount supplied to the coolant exhaust pipe120becomes larger than the coolant amount supplied to the EGR coolant supply pipe130.

Therefore, the coolant exhaust pipe120supplies a relatively larger amount of coolant to the oil cooler (not shown) or a radiator (not shown) at a high engine speed, and thus cooling efficiency is increased.

in contrast, as the rotation speed of an engine (not shown) is decreased to a low speed and thus the pressure applied to the diaphragm230of the actuator200is decreased, the restoring force of the elastic member240pulls the rod250to the left direction as shovel inFIG. 3and thus the coolant control plate300rotates counterclockwise toward the home position in this embodiment as shown inFIG. 3.

As a result, the amount of coolant supplied to the EGR coolant supply pipe130is larger than the amount of coolant supplied to the coolant exhaust pipe120.

Therefore, the EGR coolant supply pipe130supplies a relatively larger amount of coolant to the EGR cooling apparatus (not shown) at a low engine speed, and thus cooling efficiency is increased.

An exemplary embodiment in which the pressure supply pipe210is connected with an intake manifold290will now be explained.

When a rotation speed of an engine (not shown) is increased, back pressure in the intake manifold290is increased. As the back pressure in the intake manifold290is increased, the diaphragm230pulls the rod250to the left direction and the elastic member240becomes compressed. Accordingly the coolant control plate300rotates counterclockwise from the home position.

In contrast, when a rotation speed of an engine (not shown) is decreased, back pressure in the intake manifold290is decreased. As the back pressure in the intake manifold290is decreased, the restoring force of the compressed elastic member240pushes the diaphragm230and the rod250to the right direction. Accordingly the coolant control plate300rotates clockwise from the home position.

In this case, positions of the coolant supply pipe110and the coolant exhaust pipe120are changed from side to side, opposite to the case in which the pressure supply pipe210is connected with an exhaust manifold280.

Except for the positions of the coolant supply pipe110and the coolant exhaust pipe120, the operation of the actuator200and controls of supplying coolants are the same.

FIG. 4is a front view of an EGR coolant control system according to another exemplary embodiment of the present invention.

In the EGR coolant control system according to this exemplary embodiment of the present invention, a coolant connection pipe270is connected with the input portion of the coolant supply pipe110.

The flow rate of the coolant is changed in proportion to the rotation speed of an engine. That is, if the rotation speed of an engine (not shown) is increased, the input pressure in the coolant supply pipe110is increased. Thus, an operation in the case in which the coolant connection pipe270is connected with the coolant supply pipe110is identical to the case that the pressure supply pipe210is connected with the exhaust manifold280.

Excepting that the coolant connection pipe270is connected with the coolant supply pipe110, the EGR coolant control system is operated the same as when the pressure supply pipe210is connected with the exhaust manifold280, so a detailed description will be omitted.

FIG. 5is a schematic graph showing coolant flow rate according to engine operation range.

As shown inFIG. 5, when the EGR coolant control system according to an exemplary embodiment of the present invention is operated, the maximum coolant flow rate is reduced.

As described above, when the rotation speed of an engine is increased, the amount of coolant supplied to the oil cooler or the radiator becomes larger than the amount of coolant supplied to the EGR cooling apparatus. When the rotation speed of an engine is decreased, the amount of coolant supplied to the EGR cooling apparatus becomes larger than the amount of coolant supplied to the oil cooler or the radiator. Thus, cooling efficiency will be enhanced.

The EGR cooling system according to the exemplary embodiments of the present invention may reduce a maximum required amount of coolant so that the total weight of a vehicle may be reduced.