Patent Description:
Refrigerators are household appliances that are capable of store objects such as foods at a low temperature in a storage space provided in a cabinet. Since the storage space is surrounded by heat insulation wall, the inside of the storage space may be maintained at a temperature less than an external temperature.

The storage space may be classified into a refrigerating storage space or a freezing storage space according to a temperature range of the storage space.

The refrigerator may further include an evaporator for supplying cool air to the storage space. Air in the storage space is cooled while flowing to a space, in which the evaporator is disposed, so as to be heat-exchanged with the evaporator, and the cooled air is supplied again to the storage space.

Here, if the air heat-exchanged with the evaporator is contained in moisture, when the air is heat-exchanged with the evaporator, the moisture is frozen on a surface of the evaporator to generate frost on the surface of the evaporator.

Since flow resistance of the air acts on the frost, the more an amount of frost frozen on the surface of the evaporator increases, the more the flow resistance increases. As a result, heat-exchange efficiency of the evaporator may be deteriorated, and thus, power consumption may increase.

Thus, the refrigerator further include a defroster for removing the frost on the evaporator.

A defrosting cycle variable method is disclosed in <CIT> that is a prior art document.

In the prior art document, the defrosting cycle is adjusted using a cumulative operation time of the compressor and an external temperature.

However, like the prior art document, when defrosting cycle is determined only using the cumulative operation time of the compressor and the external temperature, an amount of frost (hereinafter, referred to as a frost generation amount) on the evaporator is not reflected. Thus, it is difficult accurately determine the time point at which the defrosting is required.

That is, the frost generation amount may increase or decrease according to various environments such as the user's refrigerator usage pattern and the degree to which air retains moisture. In the case of the prior art document, there is a disadvantage in that the defrosting cycle is determined without reflecting the various environments.

Accordingly, there is a disadvantage in that the defrosting does not start despite a large amount of generated frost to deteriorate cooling performance, or the defrosting starts despite a low frost generation amount to increase in power consumption due to the unnecessary defrosting.

<CIT> relates to apparatus and methods for sensing differences between the relative velocities of fluids flowing in a pair of fluid-flow paths.

<CIT> relates to a defrost control employing a differential air flow sensor.

<CIT> relates to a defrost cycle initiation system which is operable in response to the actual build-up of frost on the cooling unit thereof.

<CIT> discloses a heat pump system including an outdoor unit.

<CIT> relates to a differential pressure sensor and a refrigerator including the same.

The present invention provides a refrigerator that is capable of determining whether a defrosting operation is performed by using a parameter that varies depending on an amount of frost generated on an evaporator.

In addition, the present invention provides a refrigerator that is capable of accurately determining a time point at which defrosting is required according to an amount of frost generated on an evaporator by using a bypass passage for sensing the generated frost.

In addition, the present invention provides a refrigerator that is capable of minimizing a length of a passage for sensing generated frost.

In addition, the present invention provides a refrigerator that is capable of accurately determining a time point at which defrosting is required even though accuracy of a sensor used for determining the time point at which the defrosting is required.

In addition, the present invention provides a refrigerator that is capable of preventing frost from being generated around a sensor for sensing generated frost.

In addition, the present invention provides a refrigerator that is capable of preventing a liquid from being introduced into a bypass passage for sensing generated frost.

The invention is specified by the independent claim.

A refrigerator for achieving the above objects includes a cool air duct inside an inner case configured to define a storage space, and the cool air duct defines a heat-exchange space together with the inner case.

An evaporator is disposed in the heat exchange space, a bypass passage is disposed to be recessed in the cool air duct, and a sensor is disposed in a bypass passage.

In the present invention, the sensor is a sensor having an output value varying according to a flow rate of the air flowing through the bypass passage, and a time point at which defrosting for the evaporator is required may be determined by using the output value of the sensor.

The refrigerator according to this embodiment includes a defroster configured to remove frost generated on a surface of the evaporator and a controller configured to control the defroster based on the output value of the sensor. When it is determined that the defrosting is required, the controller may operate the defroster.

In this embodiment, the sensor may include: a heat generating element; a sensing element configured to sense a temperature of the heat generating element; and a sensor PCB on which the heat generating element and the sensing element are installed.

The sensor may further include a sensor housing configured to surround the heat generating element, the sensing element, and the sensor PCB.

In this embodiment, when a difference value between a temperature sensed by the sensing element in a state in which the heat generating element is turned on and a temperature sensed by the sensing element in a state in which the heat generating element is turned off is equal to or less than a reference temperature value, it may be determined that the defrosting is required.

In this embodiment, the refrigerator further includes a passage cover configured to cover the bypass passage so as to partition the bypass passage from the heat exchange space.

In this embodiment, the cool air duct further includes a vertical extension surface that is a surface in which the bypass passage is defined, and the passage cover includes a cover plate configured to cover the bypass passage; and a barrier extending from the cover plate, the barrier protruding downward from the vertical extension surface in a state in which the cover plate covers the bypass passage, and thus, a flow rate of the air flowing through the bypass passage before the frost is generated may be reduced.

In this embodiment, the bypass passage may extend vertically from the vertical extension surface in a straight-line shape so that the bypass passage is minimized in length.

The barrier protruding to the outside of the bypass passage may further include: a rear barrier continuously extending from the cover plate, the rear barrier being disposed adjacent to the evaporator; a plurality of side barriers extending from the rear barrier, the plurality of side barriers being spaced apart from each other in a left and right direction; and a front barrier connected to the plurality of side barriers, spaced apart from the rear barrier, and disposed at an opposite side of the evaporator with respect to the rear barrier.

In this embodiment, the cool air duct may further include an inclined surface extending to be inclined from an end of the vertical extension surface and configured to guide the air toward the evaporator.

In this embodiment, the cool air duct may further include a slot configured to define a passage for allowing the air flowing along the inclined surface to flow toward the evaporator is provided in the rear barrier. The slot may provide an air path and be defined in the rear barrier.

In this embodiment, the sensor is disposed to be spaced apart from a bottom surface of the bypass passage and the passage cover to prevent the frost from being generated around the sensor within the bypass passage.

The sensor may be disposed to be spaced apart from the inlet and the outlet of the bypass passage so as to improve sensing accuracy of the sensor and may be disposed at a point at which a distance between the bottom wall and the cover plate is bisected in the bypass passage.

In this embodiment, the bypass pass may be disposed so as not to vertically overlap the cool air inflow hole, thereby preventing the air discharged from the outlet of the bypass passage from being affected by the flow rate of the air introduced into the cool air inflow hole.

In addition, the outlet of the bypass passage may be disposed outside the limit region having a diameter greater than that of the blower fan with respect to a center of the blower fan provided in the cool air duct.

In this embodiment, a blocking rib may be provided above the bypass passage in the cool air duct to prevent a liquid from being introduced into the bypass passage.

For example, the blocking rib may have a left-right minimum length greater than a left-right minimum width of the bypass passage, and the entire bypass passage in the left and right direction may be disposed to overlap the blocking rib in the vertical direction.

According to the proposed invention, since the time point at which the defrosting is required is determined using the sensor having the output value varying according to the amount of frost generated on the evaporator in the bypass passage, the time point at which the defrosting is required may be accurately determined.

In addition, in the present invention, since the bypass passage vertically extend in the straight-line shape from the cool air duct, the length of the bypass passage may be minimized.

In addition, in the present invention, since the sensor according to the embodiment is disposed at the point, at which the change in flow rate is less, in the bypass passage and disposed in the central region of the passage in the fully development flow region.

In addition, in the present invention, in the embodiments the sensor may be disposed to be spaced apart from the bottom surface of the bypass passage and the passage cover to prevent the frost from being generated around the sensor.

In addition, in the case of the present invention, in the embodiments, since the passage cover includes the barrier protruding to the outside of the bypass passage, the flow rate in the bypass passage before the generation of the frost, the flow rate of the bypass passage may be minimized to improve the accuracy in determining of the time point, at which the defrosting is required, through the sensor.

In addition, according to the present invention, the blocking rib may be provided above the bypass passage to prevent the liquid from being introduced into the bypass passage.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. Exemplary embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. It is noted that the same or similar components in the drawings are designated by the same reference numerals as far as possible even if they are shown in different drawings.

<FIG> is a schematic longitudinal cross-sectional view of a refrigerator according to an embodiment of the present invention, <FIG> is a perspective view of a cool air duct according to an embodiment of the present invention, and <FIG> is an exploded perspective view illustrating a state in which a passage cover and a sensor are separated from each other in the cool air duct.

Referring to <FIG>, a refrigerator <NUM> according to an embodiment of the present invention includes an inner case <NUM> defining a storage space <NUM>.

The storage space may include one or more of a refrigerating storage space and a freezing storage space.

A cool air duct <NUM> providing a passage, through which cool air supplied to the storage space <NUM> flows, in a rear space of the storage space <NUM>. Also, an evaporator <NUM> is disposed between the cool air duct <NUM> and a rear wall <NUM> of the inner case <NUM>. That is, a heat exchange space <NUM> in which the evaporator <NUM> is disposed is defined between the cool air duct <NUM> and the rear wall <NUM>.

Thus, air of the storage space <NUM> may flow to the heat exchange space <NUM> between the cool air duct <NUM> and the rear wall <NUM> of the inner case <NUM> and then be heat-exchanged with the evaporator <NUM>. Thereafter, the air may flow through the inside of the cool air duct <NUM> and then be supplied to the storage space <NUM>.

The cool air duct <NUM> may include, but is not limited thereto, a first duct <NUM> and a second duct <NUM> coupled to a rear surface of the first duct <NUM>.

A front surface of the first duct <NUM> is a surface facing the storage space <NUM>, and a rear surface of the second duct <NUM> is a surface facing the rear wall <NUM> of the inner case <NUM>.

A cool air passage <NUM> may be provided between the first duct <NUM> and the second duct <NUM> in a state in which the first duct <NUM> and the second duct <NUM> are coupled to each other.

Also, a cool air inflow hole <NUM> may be defined in the second duct <NUM>, and a cool air discharge hole <NUM> may be defined in the first duct <NUM>.

A blower fan (not shown) may be provided in the cool air passage <NUM>. Thus, when the blower fan rotates, air passing through the evaporator <NUM> is introduced into the cool air passage <NUM> through the cool air inflow hole <NUM> and is discharged to the storage space <NUM> through the discharge hole <NUM>.

The evaporator <NUM> is disposed between the cool air duct <NUM> and the rear wall <NUM>. Here, the evaporator <NUM> may be disposed below the cool air inflow hole <NUM>.

Thus, the air in the storage space <NUM> ascends to be heat-exchanged with the evaporator <NUM> and then is introduced into the cool air inflow hole <NUM>.

According to this arrangement, when an amount of frost generated on the evaporator <NUM> increases, an amount of air passing through the evaporator <NUM> may be reduced.

In this embodiment, a time point at which defrosting for the evaporator <NUM> is required may be determined using a parameter that is changed according to the amount of frost generated on the evaporator <NUM>.

For example, the cool air duct <NUM> may further include a frost generation sensing portion configured so that at least a portion of the air flowing through the heat exchange space <NUM> is bypassed and configured to determine a time point, at which the defrosting is required, by using the sensor having a different output according to a flow rate of the air.

The frost generation sensing portion includes a bypass passage <NUM> bypassing at least a portion of the air flowing through the heat exchange space <NUM> and a sensor <NUM> disposed in the bypass passage <NUM>.

Although not limited, the bypass passage <NUM> may be provided in a recessed shape in the first duct <NUM>. Alternatively, the bypass passage <NUM> may be provided in the second duct <NUM>.

The bypass passage <NUM> may be provided by recessing a portion of the first duct <NUM> or the second duct <NUM> in a direction away from the evaporator <NUM>.

The bypass passage <NUM> may extend from the cool air duct <NUM> in a vertical direction.

The bypass passage <NUM> may be disposed to face the evaporator <NUM> within a left and right width range of the evaporator <NUM> so that the air in the heat exchange space <NUM> is bypassed to the bypass passage <NUM>.

The frost generation sensing portion further includes a passage cover <NUM> that allows the bypass passage <NUM> to be partitioned from the heat exchange space <NUM>.

The passage cover <NUM> may be coupled to the cool air duct <NUM> to cover at least a portion of the bypass passage <NUM> extending vertically.

The passage cover <NUM> includes a cover plate <NUM>, may include an upper extension portion <NUM> extending upward from the cover plate <NUM>, and further includes a barrier <NUM> provided below the cover plate <NUM>. A specific shape of the passage cover <NUM> will be described later with reference to the drawings.

<FIG> is a view illustrating a flow of air in the heat exchange space and the bypass passage before and after frost is generated.

(a) of <FIG> illustrates a flow of air before frost is generated, and (b) of <FIG> illustrates a flow of air after frost is generated. In this embodiment, as an example, it is assumed that a state after a defrosting operation is complicated is a state before frost is generated.

First, referring to (a) of <FIG>, in the case in which frost does not exist on the evaporator <NUM>, or an amount of generated frost is remarkably small, most of the air passes through the evaporator <NUM> in the heat exchange space <NUM> (see arrow A). On the other hand, some of the air may flow through the bypass passage <NUM> (see arrow B).

Referring to (b) of <FIG>, when the amount of frost generated on the evaporator <NUM> is large (when the defrosting is required), since the frost of the evaporator <NUM> acts as flow resistance, an amount of air flowing through the heat exchange space <NUM> may decrease (see arrow C), and an amount of air flowing through the bypass passage <NUM> may increase (see arrow D).

As described above, the amount (or flow rate) of air flowing through the bypass passage <NUM> varies according to an amount of frost generated on the evaporator <NUM>.

In this embodiment, the sensor <NUM> may have an output value that varies according to a change in flow rate of the air flowing through the bypass passage <NUM>. Thus, whether the defrosting is required may be determined based on the change in output value.

Hereinafter, a structure and principle of the sensor <NUM> will be described.

<FIG> is a schematic view illustrating a state in which the sensor is disposed in the bypass passage, <FIG> is a view of the sensor according to an embodiment of the present invention, and <FIG> is a view illustrating a thermal flow around the sensor depending on a flow of air flowing through the bypass passage.

Referring to <FIG>, the sensor <NUM> may be disposed at one point in the bypass passage <NUM>. Thus, the sensor <NUM> may contact the air flowing along the bypass passage <NUM>, and an output value of the sensor <NUM> may be changed in response to a change in a flow rate of air.

The sensor <NUM> may be disposed at a position spaced from each of an inlet <NUM> and an outlet <NUM> of the bypass passage <NUM>. A specific location of the sensor <NUM> in the bypass passage <NUM> will be described later with reference to the drawings.

Since the sensor <NUM> is disposed on the bypass passage <NUM>, the sensor <NUM> may face the evaporator <NUM> within the left and right width range of the evaporator <NUM>.

The sensor <NUM> may be, for example, a generated heat temperature sensor. Particularly, the sensor <NUM> may include a sensor PCB <NUM>, a heat generating element <NUM> installed on the sensor PCB <NUM>, and a sensing element <NUM> installed on the sensor PCB <NUM> to sense a temperature of the heat generating element <NUM>.

The heat generating element <NUM> may be a resistor that generates heat when current is applied.

The sensing element <NUM> may sense a temperature of the heat generating element <NUM>.

When a flow rate of air flowing through the bypass passage <NUM> is low, since a cooled amount of the heat generating element <NUM> by the air is small, a temperature sensed by the sensing element <NUM> is high.

On the other hand, if a flow rate of the air flowing through the bypass passage <NUM> is large, since the cooled amount of the heat generating element <NUM> by the air flowing through the bypass passage <NUM> increases, a temperature sensed by the sensing element <NUM> decreases.

The sensor PCB <NUM> may determine a difference between a temperature sensed by the sensing element <NUM> in a state in which the heat generating element <NUM> is turned off and a temperature by the sensing element <NUM> in a state in which the heat generating element <NUM> is turned on.

The sensor PCB <NUM> may determine whether the difference value between the states in which the heat generating element <NUM> is turned on/off is less than a reference difference value.

For example, referring to <FIG> and <FIG>, when an amount of frost generated on the evaporator <NUM> is small, a flow rate of air flowing to the bypass passage <NUM> is small. In this case, a heat flow of the heat generating element <NUM> is little, and a cooled amount of the heat generating element <NUM> by the air is small.

On the other hand, when the amount of frost generated on the evaporator <NUM> is large, a flow rate of air flowing to the bypass passage <NUM> is large. Then, the heat flow and cooled amount of the heat generating element <NUM> are large by the air flowing along the bypass passage <NUM>.

Thus, the temperature sensed by the sensing element <NUM> when the amount of frost generated on the evaporator <NUM> is large is less than that sensed by the sensing element <NUM> when the amount of frost generated on the evaporator <NUM> is small.

Thus, in this embodiment, when the difference between the temperature sensed by the sensing element <NUM> in the state in which the heat generating element <NUM> is turned on and the temperature by the sensing element <NUM> in the state in which the heat generating element <NUM> is turned off is less than the reference temperature difference, it may be determined that the defrosting is required.

According to this embodiment, the sensor <NUM> may sense a variation in temperature of the heat generating element <NUM>, which varies by the air of which a flow rate varies according to the amount of generated frost to accurately determine a time point, at which the defrosting is required, according to the amount of frost generated on the evaporator <NUM>.

The sensor <NUM> may further include a sensor housing <NUM> to prevent the air flowing through the bypass passage <NUM> from directly contacting the sensor PCB <NUM>, the heat generating element <NUM>, and the temperature sensor <NUM>.

In the sensor housing <NUM>, a wire connected to the sensor PCB <NUM> is withdrawn in a state in which one side of the sensor housing <NUM> is opened. Thereafter, the opened portion may be covered by the cover portion.

The sensor housing <NUM> may surround the sensor PCB <NUM>, the heat generating element <NUM>, and the temperature sensor <NUM>.

<FIG> is a view illustrating a position of the sensor in the bypass passage, <FIG> is a view illustrating an air flow pattern in the bypass passage, and <FIG> is a view illustrating a flow of air in the state in which the sensor is installed in the bypass passage.

Referring to <FIG> and <FIG>, the passage cover <NUM> may cover a portion of the bypass passage <NUM> in the vertical direction.

Thus, the air may flow along a region (that is partitioned from the heat exchange space) of the bypass passage <NUM>, in which the passage cover <NUM> substantially exists.

As described above, the sensor <NUM> may be disposed to be spaced apart from the inlet <NUM> and the outlet <NUM> of the bypass passage <NUM>.

The sensor <NUM> may be disposed at a position at which the sensor <NUM> is less affected by a change in flow of the air flowing through the bypass passage <NUM>.

For example, the sensor <NUM> may be disposed at a position (hereinafter, referred to as an "inlet reference position") that is spaced at least 6Dg (or <NUM> * diameter of the passage) from the inlet (actually, a lower end of the passage cover <NUM>) of the bypass passage <NUM>.

Alternatively, the sensor <NUM> may be disposed at a position (hereinafter, referred to as an "outlet reference position") that is spaced at least 3Dg (or <NUM> * diameter of the passage) from the outlet (actually, an upper end of the passage cover <NUM>) of the bypass passage <NUM>.

A change in flow of air is severe while the air is introduced into the bypass passage <NUM> or discharged from the bypass passage <NUM>.

If the change in flow of air is large, it may be wrongly determined that the defrosting is required despite a small amount of generated frost. Thus, in this embodiment, when air flows along the bypass passage <NUM>, the sensor <NUM> is installed at a position at which the change in flow is small to reduce detection errors.

For example, the sensor <NUM> may be disposed within a range between the inlet reference position and the outlet reference position. The sensor <NUM> may be disposed closer to the outlet reference position than the inlet reference position. Therefore, the sensor <NUM> may be disposed closer to the outlet <NUM> than the inlet <NUM> in the bypass passage <NUM>.

Since the flow is stabilized at least at the inlet reference position, and the flow is stabilized until the outlet reference position, if the sensor <NUM> is disposed close to the outlet reference position, the air having the stabilized flow may contact the sensor <NUM>.

Thus, since it is not affected other than the flow change due to the large and small amount of generated frost, the sensing accuracy of the sensor <NUM> may be improved.

Also, referring to <FIG>, the farther away from the inlet <NUM> in the bypass passage <NUM>, the air becomes a fully developed flow form.

Since the sensor <NUM> is very sensitive to the change in flow of air, when the sensor <NUM> is disposed at a center of the bypass passage <NUM> at the point at which the fully developed flow occurs, the sensor <NUM> may accurately sense the change in flow.

Thus, as illustrated in <FIG>, the sensor <NUM> may be installed in a central region within the bypass passage <NUM>.

Here, the central region of the bypass passage <NUM> is a region including a portion at which a distance between the bottom wall <NUM> of the recessed portion of the bypass passage <NUM> and the passage cover <NUM> is bisected. That is, a portion of the sensor <NUM> may be disposed at a point at which the distance between the bottom wall <NUM> of the recessed portion of the bypass passage <NUM> and the passage cover <NUM> is bisected.

Referring to <FIG>, the sensor <NUM> is spaced apart from the bottom wall <NUM> of the bypass passage <NUM> and the passage cover <NUM>. Thus, a portion of the air in the bypass passage <NUM> may flow through a space between the bottom wall <NUM> and the sensor <NUM>, and the other portion of the air may flow through a space between the sensor <NUM> and the passage cover <NUM>.

In summary, the sensor <NUM> has to be installed in the central region of the passage at the point at which the change in flow of air is minimized in the bypass passage <NUM> and at the point at which the fully developed flow flows so as to improve accuracy sensing.

Due to this arrangement, the sensor <NUM> may sensitively react to the change in flow of air according to the large or small amount of generated frost. That is, a variation in temperature sensed by the sensor <NUM> may increase.

As described above, when the variation in temperature sensed by the sensor <NUM> increases, it is possible to determine the time point at which the defrosting is required even if the temperature sensing accuracy of the sensor <NUM> itself is lowered.

Since the temperature sensing accuracy of the sensor itself is related to prices, it is possible to determine the time point at which the defrosting is required even if the sensor <NUM> having a relatively low price due to low accuracy is used.

<FIG> is a view illustrating an arrangement of the bypass passage and the passage cover in the cool air duct according to an embodiment of the present invention.

Referring to <FIG>, a lower end 260a of the passage cover <NUM> may be disposed at a height similar to that of a lower end of the evaporator <NUM> or a height less than that of the lower end of the evaporator <NUM>.

According to this arrangement, when the amount of frost generated on the evaporator <NUM> increases, the air may easily flow to the bypass passage <NUM>.

In this embodiment, since the blower fan is disposed in the cool air duct <NUM>, when the blower fan rotates, a portion of the air inflow hole <NUM> of the cool air duct <NUM> may serve as a low pressure region.

Also, since the air flows upward along the evaporator <NUM>, a lower side of the evaporator <NUM> with respect to the evaporator <NUM> may serve as a high pressure region, and an upper side of the evaporator <NUM> with respect to the evaporator <NUM> may serve as a low pressure region.

In this embodiment, the upper end 260b of the passage cover <NUM> may be disposed in the low pressure region.

Thus, since the lower end 260a of the passage cover <NUM> is disposed in the high pressure region, and the upper end 260b is disposed in the low pressure region, the flow of the air to the bypass passage <NUM> is possible.

In addition, in this embodiment, the upper end 260b of the passage cover <NUM> may be disposed higher than the evaporator <NUM>. Thus, the phenomenon in which the air discharged from the bypass passage <NUM> is affected by the air passing through the evaporator may be reduced.

The bypass passage <NUM> may be disposed so as not to vertically overlap the air flow hole <NUM>. This is to prevent the air discharged from the outlet <NUM> of the bypass passage <NUM> from being affected by the air introduced into the air flow hole <NUM>.

Also, the outlet <NUM> of the bypass passage <NUM> may be disposed lower than a center C of the blower fan. Also, the outlet <NUM> of the bypass passage <NUM> may be disposed lower than the lowest point of the air flow hole <NUM>.

In this embodiment, the air flow hole <NUM> has a diameter D1, and the blower fan has a diameter D2. The diameter D2 of the blower fan may be greater than the diameter D1 of the air flow hole <NUM>.

A limit region having a diameter D3 greater than the diameter D2 of the blower fan may be set based on the center C of the blower fan, and the outlet <NUM> of the bypass passage <NUM> may be disposed in a region outside the limit region having the diameter D3.

Also, to minimize a length of the bypass passage <NUM>, the bypass passage <NUM> may extend vertically in a straight line shape in the region outside the limit region.

Here, although not limited, the diameter D3 may be set to <NUM> times or more of the diameter of the blower fan.

Since the air is introduced into the cool air duct <NUM> through the air flow hole <NUM>, a flow velocity in the air flow hole <NUM> is fast.

Also, due to the fast flow rate of the air flow hole <NUM>, the flow velocity of the air in the region having the diameter D3 is fast.

If the outlet <NUM> of the bypass passage <NUM> is disposed in the limit region, there is a change in flow of air in the bypass passage <NUM> due to the effect of a fast flow velocity, and thus, the sensing accuracy of the sensor <NUM> is reduced.

Thus, in this embodiment, the bypass passage <NUM> may extend in the straight line shape so as not to be affected by the air having a fast flow velocity around the air flow hole <NUM> while reducing the length of the bypass passage <NUM>, and the outlet <NUM> may be disposed outside the limit region.

<FIG> is an enlarged view illustrating the bypass passage and a rib for preventing defrosting water from being introduced according to an embodiment of the present invention.

Referring to <FIG> and <FIG>, since the air flowing through the bypass passage <NUM> contains moisture, frost may be generated in the passage due to a capillary phenomenon in a space between the sensor <NUM> and a wall defined by the bypass passage <NUM> in the bypass passage <NUM>.

Thus, in this embodiment, the sensor <NUM> may be spaced apart from the bottom wall <NUM> of the bypass passage <NUM> and the passage cover <NUM> to prevent the frost from being generated in the passage.

Although not limited, the sensor <NUM> may be designed to be spaced at least <NUM> from each of the bottom wall <NUM> and the passage cover <NUM> (which may be referred to as a "minimum separation distance").

Thus, a depth D of the bypass passage <NUM> may be equal to or larger than a thickness of (<NUM> * the minimum separation distance) and the sensor <NUM>.

The left and right width W of the bypass passage <NUM> may be greater than the depth D.

If the left and right width W of the bypass passage <NUM> are larger than the depth D, when the air flows to the bypass passage <NUM>, a contact area between the air and the sensor <NUM> increases, and thus, the variation in temperature detected by the sensor <NUM> may increase.

The cool air duct <NUM> may be provided with a blocking rib <NUM> for preventing a liquid such as defrosting water or moisture generated by being melted during the defrosting process from being introduced into the bypass passage <NUM>.

The blocking rib <NUM> may be disposed above the outlet <NUM> of the bypass passage <NUM>. The blocking rib <NUM> may have a protrusion shape protruding from the cool air duct <NUM>.

The blocking rib <NUM> may allow the dropping liquid to be spread horizontally so as to prevent the liquid from being introduced into the bypass passage <NUM>.

The blocking rib <NUM> may be provided horizontally in a straight line shape or be provided in a rounded shape to be convex upward.

The blocking rib <NUM> may be disposed to overlap with the entire left and right side of the bypass passage <NUM> in the vertical direction and may have a minimum left and right length greater than the right and left width of the bypass passage <NUM>.

When the blocking rib <NUM> is provided in the cool air duct <NUM>, since the blocking rib <NUM> serves as flow resistance of air, the minimum left and right length of the blocking rib <NUM> may be set to two times or less of the right and left width W.

As the blocking rib <NUM> is disposed closer to the bypass passage <NUM>, the length of the blocking rib <NUM> may be shortened. On the other hand, the defrosting water may flow over the blocking rib <NUM> and then be introduced into the bypass passage <NUM>.

Thus, the blocking rib <NUM> may be spaced apart from the bypass passage <NUM> in the vertical direction, and the maximum separation distance may be set within a range of the right and left width W of the bypass passage <NUM>.

The cool air duct <NUM> may further include a sensor installation groove <NUM> recessed to install the sensor <NUM>.

The cool air duct <NUM> may include a bottom wall <NUM> and both sidewalls <NUM> and <NUM> for providing the bypass passage <NUM>, and the sensor installation groove <NUM> may be recessed in one or more of both the sidewall <NUM> and <NUM>.

In the state in which the sensor <NUM> is installed in the sensor installation groove <NUM>, the sensor <NUM> may be spaced the minimum separation distance from the bottom wall <NUM> and the passage cover <NUM> as described above.

<FIG> is a view illustrating a barrier of the passage cover according to an embodiment of the present invention, <FIG> is a view illustrating a variation in temperature sensed by the sensor depending on a protruding length of the barrier, and <FIG> is a cross-sectional view of the barrier, taken along line A-A of <FIG>.

<FIG> is a view illustrating a change in flow of air depending on whether a slot is provided in the barrier, and <FIG> is a view illustrating a variation in temperature sensed by the sensor depending on a length of the slot defined in the barrier.

<FIG> is a view illustrating a flow of air introduced into the heat exchange space according to an embodiment of the present invention.

Referring to <FIG>, <FIG>, and <FIG>, the passage cover <NUM> includes a cover plate <NUM> and a barrier <NUM> and may include an upper extension portion <NUM>.

The cover plate <NUM> may cover the bypass passage <NUM> and may be provided in a thin plate shape. For example, the cover plate <NUM> may cover the bypass passage <NUM> in a state of being spaced apart from the bottom wall <NUM>.

A seating groove 235a for seating the cover plate <NUM> may be defined vertically in the cool air duct <NUM>. When the cover plate <NUM> is seated in the seating groove 235a, an outer surface of the cover plate <NUM> may provide a substantially continuous surface with respect to the cool air duct <NUM>.

The upper extension portion <NUM> may also cover a portion of the bypass passage <NUM> and extend to be inclined at a predetermined angle from the cover plate <NUM>.

The upper extension portion <NUM> is configured to extend to be inclined from the cover plate <NUM> corresponding to a portion (<NUM>: hereinafter, referred to as an "upper inclined portion") of the cool air duct <NUM>.

If the cool air duct <NUM> does not include an upper inclined portion, the upper extension portion <NUM> may be omitted, and the cover plate <NUM> may be provided in the straight line shape.

The upper extension portion <NUM> covers only a portion of the bypass passage <NUM>. Thus, a portion of the bypass passage <NUM> is exposed to the outside to be the outlet <NUM>.

A portion of the barrier <NUM> is disposed outside the bypass passage <NUM> while the cover plate <NUM> covers the bypass passage <NUM>. The barrier <NUM> protrudes downward from upper and lower extension surfaces <NUM> of the cool air duct <NUM>.

Thus, one portion of the barrier <NUM> is disposed in the bypass passage <NUM>, and the other portion protrudes downward from the bypass passage <NUM>.

Specifically, the barrier <NUM> includes a rear barrier <NUM> disposed close to the evaporator <NUM>, a front barrier <NUM> spaced forward from the rear barrier <NUM>, and a plurality of side barriers <NUM> and <NUM> connecting the front barrier <NUM> to the rear barrier <NUM>. The plurality of side barriers <NUM> and <NUM> may be spaced apart from each other in the left-right direction. Although not limited, the plurality of side barriers <NUM> and <NUM> may be disposed in parallel to each other.

The rear barrier <NUM> is a wall provided to be continuous with the cover plate <NUM>. The plurality of side barriers <NUM> and <NUM> are walls extending forward from the rear barrier <NUM>. The front barrier <NUM> is a wall connecting front ends of the plurality of side barriers <NUM> and <NUM> to each other.

The front barrier <NUM> is disposed at an opposite side of the evaporator <NUM> with respect to the rear barrier <NUM>.

Then, a bottom surface of the barrier <NUM> is opened. Thus, a guide passage <NUM> for guiding air to the bypass passage <NUM> is provided by the front barrier <NUM>, the plurality of side barriers <NUM> and <NUM>, and the rear barrier <NUM>.

The guide passage <NUM> is a passage communicating with the bypass passage <NUM> at the outside of the bypass passage <NUM>. The guide passage <NUM> also serves as the bypass passage.

In the cool air duct <NUM>, a vertical extension surface <NUM> in which the bypass passage <NUM> is provided is a substantially vertical surface.

The bypass passage <NUM> may extend vertically in a straight line shape from the vertical extension surface <NUM>.

The cool air duct <NUM> may further include an inclined surface <NUM> extending from a lower end of the vertical extension surface <NUM>. The inclined surface <NUM> may extend downward as a distance from the evaporator <NUM> increases.

The inclined surface <NUM> is a surface that guides the air in the storage space <NUM> to the heat exchange space <NUM>.

Thus, the air in the storage space <NUM> may flow to be inclined upward by the inclined surface <NUM> when viewed from a side surface of the heat exchange space <NUM>.

In this embodiment, the barrier <NUM> may serve to limit an introduction of the air flowing to the heat exchange space <NUM> into the bypass passage <NUM> when an amount of frost generated on the evaporator <NUM> is small.

On the other hand, the barrier <NUM> may serve to effectively guide the air introduced into the heat exchange space <NUM> to the bypass passage <NUM> when an amount of frost generated on the evaporator <NUM> is large.

As described above, when the change in flow rate of the air increases due to the large and small amount of frost generated on the evaporator <NUM>, the sensing accuracy of the sensor <NUM> may be improved by the barrier <NUM>.

That is, if the change in flow rate of the air is large due to the large and small amount of frost generated on the evaporator <NUM>, the variation in temperature sensed by the sensor <NUM> is large, and thus, the time point at which the defrosting is required may be accurately determined.

In addition, as described above, when the variation in temperature sensed by the sensor <NUM> increases due to the large and small amount of frost generated on the evaporator <NUM>, even when the sensor <NUM> having low sensor accuracy is used, the time point at which the defrosting is required may be determined.

In this embodiment, a flow rate of air introduced into the bypass passage <NUM> may vary according to a length of the barrier <NUM> protruding from the lower end (that is a boundary between the vertical extension surface <NUM> and the inclined surface <NUM>) of the vertical extension surface <NUM>.

Referring to <FIG>, a horizontal axis represents the protruding length of the barrier, and a vertical axis represents the variation in temperature before and after the frost generation.

When the protruding length of the barrier <NUM> is short, the flow rate of the air flowing through the bypass passage <NUM> increases even before the frost generation.

When the flow rate of the air flowing through the bypass passage <NUM> is large before the frost generation, the variation in temperature sensed by the sensor <NUM> (for example, a difference value between the highest temperature and the lowest temperature) is large. Thus, the flow rate of the air flowing through the bypass passage <NUM> is large even after the frost generation, and the variation in temperature sensed by the sensor <NUM> is large.

As a result, the variation between the temperature sensed by the sensor <NUM> before the frost generation and the temperature sensed by the sensor <NUM> after the frost generation (for example, the difference between the lowest temperature before the frost generation and the lowest temperature after the frost generation) decreases.

On the other hand, when the protruding length of the barrier <NUM> increases, the flow rate of the air flowing through the bypass passage <NUM> before the frost generation decreases. The variation in temperature sensed by the sensor <NUM> before the frost generation decreases.

On the other hand, since the variation in temperature sensed by the sensor <NUM> is large after the frost generation, the variation between the temperature sensed by the sensor <NUM> before the frost generation and the temperature sensed by the sensor <NUM> after the frost generation increases.

However, when the protruding length of the barrier <NUM> is too long, the flow rate of the air flowing into the bypass passage <NUM> decreases before and after the frost generation. As a result, the variation between the temperature sensed by the sensor <NUM> before the frost generation and the temperature sensed by the sensor <NUM> after the frost generation decreases.

Accordingly, the protrusion length of the barrier <NUM> may be set to a value ranging of about <NUM> to about <NUM> so that the variation in temperature sensed by the sensor <NUM> before and after the frost generation is greater than the reference variation.

The lower end of the barrier <NUM> may be horizontally disposed. For example, the front barrier <NUM> and the plurality of side barriers <NUM> and <NUM> may be disposed on substantially the same horizontal plane.

In this case, as illustrated in (a) of <FIG>, since the air in the storage space <NUM> flows upward along the inclined surface <NUM>, when the air, which passes through the front barrier <NUM>, of the air that flows to be inclined collides with the rear barrier <NUM>, the air flows to the bypass passage <NUM> without flowing to the evaporator <NUM>.

In this case, the flow rate of the air flowing into the bypass passage <NUM> increases regardless of the amount of generated frost.

In the case of this embodiment, the accuracy of determining the time point at which the defrosting is required may be improved only when the flow rate of the air flowing through the bypass passage <NUM> is minimized before the frost generation.

Thus, a slot <NUM> providing a flow path of air may be defined in the rear barrier <NUM> so that the air passing through the lower end of the front barrier <NUM> flows directly to the evaporator <NUM>.

When the slot <NUM> is defined in the rear barrier <NUM> as illustrated in (b) of <FIG>, the air passing through the lower end of the front barrier <NUM> may not collide with the rear barrier <NUM> and thus may not directly flow to the evaporator <NUM>.

In this embodiment, the air colliding with the front barrier <NUM> flows along the plurality of side barriers <NUM> and <NUM> and then flows toward the rear barrier <NUM>.

When the slot <NUM> is not defined in the rear barrier <NUM>, the air flowing along the side barriers <NUM> and <NUM> does not flow to the bypass passage <NUM> but flows to the evaporator <NUM>.

On the other hand, when the slot <NUM> is defined in the rear barrier <NUM>, the air flowing along the side barriers <NUM> and <NUM> flows to the bypass passage <NUM> by the slot <NUM>.

Thus, in this embodiment, the flow rate of the air flowing to the bypass passage <NUM> may be determined actually by the flow rate of the air directly introduced into the guide passage <NUM> of at least the barrier <NUM> and the flow rate of the air introduced into the barrier <NUM> along the slot <NUM> after flowing along a circumference of the barrier <NUM>.

In this embodiment, if a length of the slot <NUM> (a height from the lower end of the barrier <NUM>) is small, the flow rate of the air flowing into the bypass passage <NUM> is large, and when the slot <NUM> increases in length, the flow rate of the air flowing into the bypass passage <NUM> is reduced.

However, if the length of the slot <NUM> is too long, the flow rate of the air flowing through the slot <NUM> after flowing along the side barriers <NUM> and <NUM> increases, and even before the frost generation, the flow rate of the air flowing into the bypass passage <NUM> increases.

Thus, in this embodiment, the length of the slot may be set to a value ranging of about <NUM> to about <NUM> so that the flow rate of the air flowing into the bypass passage <NUM> is minimized before the frost generation. Although not limited, the length of the slot <NUM> may be designed within a range of about <NUM>/<NUM> to about <NUM>/<NUM> of the protruding length of the barrier <NUM>.

<FIG> is a control block diagram of the refrigerator according to an embodiment of the present invention.

Referring to <FIG>, the refrigerator <NUM> according to an embodiment of the present invention may further include a defroster <NUM> operating to defrost the evaporator <NUM> and a controller <NUM> controlling the defroster <NUM>.

The defroster <NUM> may include, for example, a heater. When the heater is turned on, heat generated by the heater is transferred to the evaporator <NUM> to melt frost generated on the surface of the evaporator <NUM>.

The controller <NUM> may control the heat generating element <NUM> of the sensor <NUM> so as to be turned on with a regular cycle.

To determine the time point at which the defrosting is required, the heat generating element <NUM> may be maintained in the turn-on state for a certain time, and a temperature of the heat generating element <NUM> may be sensed by the sensing element <NUM>.

After the heat generating element <NUM> is turned on for the certain time, the heat generating element <NUM> may be turned off, and the sensing element <NUM> may sense the temperature of the off heat generating element <NUM>. Also, the sensor PCB <NUM> may determine whether a maximum value of the temperature difference value in the turn on/off state of the heat generating element <NUM> is equal to or less than the reference difference value.

Then, when the maximum value of the temperature difference value in the turn on/off state of the heat generating element <NUM> is equal to or less than the reference difference value, it is determined that defrosting is required. Thus, the defroster <NUM> may be turned on by the controller <NUM>.

Claim 1:
A refrigerator comprising:
an inner case (<NUM>) configured to define a storage space (<NUM>);
a cool air duct (<NUM>) configured to guide a flow of air within the storage space (<NUM>), the cool air duct (<NUM>) being configured to define a heat exchange space (<NUM>) together with the inner case (<NUM>);
an evaporator (<NUM>) disposed in the heat exchange space (<NUM>) between the inner case (<NUM>) and the cool air duct (<NUM>);
a bypass passage (<NUM>) disposed to be recessed in the cool air duct (<NUM>), the bypass passage (<NUM>) being configured so that the air flows to bypass the evaporator (<NUM>);
a sensor (<NUM>) disposed in the bypass passage (<NUM>), the sensor (<NUM>) having an output value varying according to a flow rate of the air flowing through the bypass passage (<NUM>);
a defroster (<NUM>) configured to remove frost generated on a surface of the evaporator (<NUM>); and
a controller (<NUM>) configured to control the defroster (<NUM>) based on the output value of the sensor (<NUM>);
wherein the refrigerator further comprises
a passage cover (<NUM>) configured to cover the bypass passage (<NUM>) so as to partition the bypass passage (<NUM>) from the heat exchange space (<NUM>),
wherein the cool air duct (<NUM>) comprises a bottom wall (<NUM>) and both sidewalls (<NUM>, <NUM>), which define the bypass passage (<NUM>), characterized in that
the passage cover (<NUM>) comprises a cover plate (<NUM>) configured to cover the bypass passage (<NUM>) in a state of being spaced apart from the bottom wall (<NUM>), and
the sensor (<NUM>) is disposed to be spaced apart from the bottom wall (<NUM>) and the cover plate (<NUM>) in the bypass passage (<NUM>),
wherein the cool air duct (<NUM>) comprises a vertical extension surface (<NUM>) that is a surface in which the bypass passage (<NUM>) is defined, and
the passage cover (<NUM>) further comprises
a barrier (<NUM>) extending from the cover plate (<NUM>), the barrier (<NUM>) protruding downward from the vertical extension surface (<NUM>) in a state in which the cover plate (<NUM>) covers the bypass passage (<NUM>).