Patent Description:
Generally, a scroll compressor is being widely used at an air conditioner, etc., in order to compress a refrigerant, owing to its advantages that a compression ratio is relatively higher than that of other types of compressors, and a stable torque is obtainable since processes for sucking, compressing and discharging a refrigerant are smoothly performed.

A behavior characteristic of the scroll compressor is determined by a non-orbiting wrap (hereinafter, will be referred to as a fixed wrap) of a non-orbiting scroll (hereinafter, will be referred to as a fixed scroll) and an orbiting wrap of an orbiting scroll. The fixed wrap and the orbiting wrap may have any shape, but they generally have a shape of an involute curve for easy processing. The involute curve means a curved line corresponding to a moving path drawn by the end of a thread when the thread wound around a basic circle having any radius is unwound. In case of using such an involute curve, the fixed wrap and the orbiting wrap stably perform a relative motion since they have a constant thickness, thereby forming a compression chamber to compress a refrigerant.

The compression chamber of the scroll compressor has a suction chamber at an outer side and a discharge chamber at an inner side, as a volume of the compression chamber is reduced towards the inner side from the outer side. Thus, the fixed scroll and the orbiting scroll form a high temperature towards the inner side, due to compression heat. Especially, in case of a scroll compressor which satisfies a high temperature and a high compression ratio, an inner compression chamber has a much higher temperature than an outer compression chamber.

Accordingly, the fixed scroll and the orbiting scroll have a largest thermal expansion ratio at a central region, and a thermal expansion ratio is gradually reduced towards an edge region. However, a total thermal expansion amount is largest at the edge region, since a thermal expansion amount generated from the central region is accumulated at the edge region. Thus, the fixed wrap of the fixed scroll and the orbiting wrap of the orbiting scroll may partially contact each other at the edge region, resulting in a frictional loss. This may cause abrasion of a side surface of the fixed wrap or a side surface of the orbiting wrap, resulting in leakage of a compressed refrigerant. Especially, when the fixed scroll and the orbiting scroll are formed of different materials, for instance, when the fixed scroll is formed of cast-iron and the orbiting scroll is formed of a material having a light weight and a high thermal expansion coefficient (e.g., aluminum), the orbiting scroll has a larger thermal deformation than the fixed scroll. This may significantly increase a frictional loss or abrasion.

Further, there is a limitation in selecting materials of the fixed scroll and the orbiting scroll. In case of driving the scroll compressor with a high compression ratio, a larger amount of compression heat may be generated to increase a deformation amount of the orbiting scroll. This may cause a limitation in designing the scroll compressor with a high compression ratio.

<CIT> relates to a scroll compressor comprising an arcuate section, formed from a suction end of a wrap to a first point, and a logarithmic spiral section with an increasing thickness formed from a second point to a discharge end of the wrap.

<CIT> relates to a scroll compressor in which the lap thickness of a fixed scroll or the lap thickness of a slew scroll is partially reduced and machined.

<CIT> relates to a scroll type compressor that has a stationary scroll and a movable scroll rotating around the former in an orbital manner, while forming volume variable sealed spaces therebetween to compress a coolant gas.

<CIT> relates to a compressor including a passage separator provided between an electric motor drive and a compression device to separate a refrigerant passage from an oil passage. The passage separator includes a first partition wall and a second partition wall. The first partition wall is disposed between an inner circumferential surface of a casing and a discharge hole of the compression device, and the second partition wall is disposed between the discharge hole and a balance weight.

<CIT> discloses a compressor including a fixed wrap and an orbiting scroll having an orbiting wrap engaged with the fixed wrap to form compression chambers, the fixed wrap and the orbiting wrap having irregular curves.

Therefore, an aspect of the detailed description is to provide a scroll compressor capable of minimizing a frictional loss or abrasion by preventing interference between a fixed wrap and an orbiting wrap due to thermal expansion.

Another aspect of the detailed description is to provide a scroll compressor capable of easily selecting materials of a fixed scroll and an orbiting scroll.

Another aspect of the detailed description is to provide a scroll compressor capable of reducing a limitation in designing a compression ratio.

The present invention is defined by independent claim <NUM>; the dependent claims define embodiments of the invention.

The compression chamber may include a first compression chamber formed on an inner side surface of the fixed wrap, and a second compression chamber formed on an outer side surface of the fixed wrap. The first compression chamber may be defined between two contact points P11 and P12 generated as the inner side surface of the fixed wrap contacts an outer side surface of the orbiting wrap. And a formula of <NUM>° < α < <NUM>° may be formed, wherein α is an angle defined by two lines which connect a center O of the eccentric portion to the two contact points P1 and P2, respectively.

The scroll compressor of the present invention may have the following advantages.

Firstly, interference between the fixed wrap and the orbiting wrap may be prevented, even if a thermal deformation is increased towards an edge region from a central region due to thermal expansion of the fixed scroll or the orbiting scroll while the scroll compressor is being operated, because a gap between the fixed wrap and the orbiting wrap is gradually increased toward the edge region. This may significantly reduce a frictional loss or abrasion due to interference between the fixed wrap and the orbiting wrap.

Further, a limitation in selecting materials of the fixed scroll and the orbiting scroll may be reduced, since interference between the fixed scroll and the orbiting scroll due to a thermal transformation of the fixed wrap or the orbiting wrap is reduced. This may allow a light material to be selected without consideration of a thermal transformation even under a high temperature and a high pressure, resulting in enhanced efficiency.

Further, since a thermal transformation of the fixed wrap or the orbiting wrap is reduced, a wrap design suitable for a high compression ratio may be implemented.

Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from the detailed description.

Hereinafter, a scroll compressor according to the present invention will be explained in more detail with reference to the attached drawings. For reference, the scroll compressor according to the present invention is to reduce a frictional loss and abrasion between a fixed wrap and an orbiting wrap due to thermal expansion, by controlling an interval between the fixed wrap and the orbiting wrap. Thus, the present invention may be applied to any type of scroll compressor having a fixed wrap and an orbiting wrap. However, for convenience, will be explained a lower compression type scroll compressor where a compression part is disposed below a motor part, more specifically, a scroll compressor where a rotation shaft is overlapped with an orbiting wrap on the same plane. Such a scroll compressor is appropriate to be applied to a refrigerating cycle of a high temperature and a high compression ratio.

<FIG> is a longitudinal sectional view illustrating an example of a lower compression type scroll compressor according to the present invention, and <FIG> is a sectional view taken along line 'IV-IV' in <FIG>.

Referring to <FIG>, the lower compression type scroll compressor according to this embodiment of the present invention may include a casing <NUM> having an inner space 1a; a motor part <NUM> provided at the inner space 1a of the casing <NUM>, and configured to generate a rotational force in the form of a driving motor; a compression part <NUM> disposed below the motor part <NUM>, and configured to compress a refrigerant by receiving the rotational force of the motor part <NUM>.

The casing <NUM> may include a cylindrical shell <NUM> which forms a hermetic container; an upper shell <NUM> which forms the hermetic container together by covering an upper part of the cylindrical shell <NUM>; and a lower shell <NUM> which forms the hermetic container together by covering a lower part of the cylindrical shell <NUM>, and which forms an oil storage space 1b.

A refrigerant suction pipe <NUM> may be penetratingly-formed at a side surface of the cylindrical shell <NUM>, thereby being directly communicated with a suction chamber of the compression part <NUM>. And a refrigerant discharge pipe <NUM> communicated with the inner space 1a of the casing <NUM> may be installed at an upper part of the upper shell <NUM>. The refrigerant discharge pipe <NUM> may be a passage along which a refrigerant compressed by the compressor <NUM> and discharged to the inner space 1a of the casing <NUM> is discharged to the outside. And an oil separator (not shown) for separating oil mixed with the discharged refrigerant may be connected to the refrigerant discharge pipe <NUM>.

A stator <NUM> which constitutes the motor part <NUM> may be installed at an upper part of the casing <NUM>, and a rotor <NUM> which constitutes the motor part <NUM> together with the stator <NUM> and rotated by a reciprocal operation with the stator <NUM> may be rotatably installed in the stator <NUM>.

A plurality of slots (not shown) may be formed on an inner circumferential surface of the stator <NUM> in a circumferential direction, thereby winding a coil <NUM> thereon. And an oil collection passage <NUM> configured to pass oil therethrough may be formed between an outer circumferential surface of the stator <NUM> and an inner circumferential surface of the cylindrical shell <NUM>, in a D-cut shape.

A main frame <NUM> which constitutes the compression part <NUM> may be fixed to an inner circumferential surface of the casing <NUM>, below the stator <NUM> with a predetermined gap therebetween. The main frame <NUM> may be coupled to the cylindrical shell <NUM> as an outer circumferential surface of the main frame <NUM> is welded or shrink-fit to an inner circumferential surface of the cylindrical shell <NUM>.

A ring-shaped frame side wall portion (first side wall portion) <NUM> may be formed at an edge of the main frame <NUM>, and a first shaft accommodating portion <NUM> configured to support a main bearing portion <NUM> of a rotation shaft <NUM> to be explained later may be formed at a central part of the main frame <NUM>. A first shaft accommodating hole 312a, configured to rotatably insert the main bearing portion <NUM> of the rotation shaft <NUM> and support the main bearing portion <NUM> in a radius direction, may be penetratingly-formed at the first shaft accommodating portion <NUM> in an axial direction.

A fixed scroll <NUM> may be installed at a bottom surface of the main frame <NUM>, in a state where an orbiting scroll <NUM> eccentrically-coupled to the rotation shaft <NUM> is disposed between the fixed scroll <NUM> and the main frame <NUM>. The fixed scroll <NUM> may be fixedly-coupled to the main frame <NUM>, and may be fixed to the main frame <NUM> so as to be moveable in an axial direction.

The fixed scroll <NUM> may include a fixed plate portion (hereinafter, will be referred to as a first plate portion) <NUM> formed in an approximate disc shape, and a scroll side wall portion (hereinafter, will be referred to as a second side wall portion) <NUM> formed at an edge of the first plate portion <NUM> and coupled to an edge of a bottom surface of the main frame <NUM>.

A fixed wrap <NUM>, which forms a compression chamber (V) by being engaged with an orbiting wrap <NUM> to be explained later, may be formed on an upper surface of the first plate portion <NUM>. The compression chamber (V) may be formed between the first plate portion <NUM> and the fixed wrap <NUM>, and between the orbiting wrap <NUM> to be explained later and the second plate portion <NUM>. And the compression chamber (V) may be implemented as a suction chamber, an intermediate pressure chamber and a discharge chamber are consecutively formed in a moving direction of the wrap.

The compression chamber (V) may include a first compression chamber (V1) formed between an inner side surface of the fixed wrap <NUM> and an outer side surface of the orbiting wrap <NUM>, and a second compression chamber (V2) formed between an outer side surface of the fixed wrap <NUM> and an inner side surface of the orbiting wrap <NUM>.

That is, as shown in <FIG>, the first compression chamber (V1) is formed between two contact points (P11, P12) generated as the inner side surface of the fixed wrap <NUM> and the outer side surface of the orbiting wrap <NUM> come in contact with each other. Under an assumption that a largest angle among angles formed by two lines which connect a center (O) of an eccentric portion with two contact points (P11, P12) is α, a formula (α < <NUM>°) is formed before a discharge operation is started. And the second compression chamber (V2) is formed between two contact points (P21, P22) generated as the outer side surface of the fixed wrap <NUM> and the inner side surface of the orbiting wrap <NUM> come in contact with each other.

The first compression chamber (V1) is formed such that a refrigerant is firstly sucked thereinto than the second compression chamber (V2), and such that a compression path thereof is relatively long. However, since the orbiting wrap <NUM> is formed with irregularity, a compression ration of the first compression chamber (V1) is lower than that of the second compression chamber (V2). Further, the second compression chamber (V2) is formed such that a refrigerant is later sucked thereinto than the first compression chamber (V1), and such that a compression path thereof is relatively short. However, since the orbiting wrap <NUM> is formed with irregularity, a compression ration of the second compression chamber (V2) is higher than that of the first compression chamber (V1).

A suction opening <NUM>, through which a refrigerant suction pipe <NUM> and a suction chamber are communicated with each other, is penetratingly-formed at one side of the second side wall portion <NUM>. And a discharge opening <NUM>, communicated with a discharge chamber and through which a compressed refrigerant is discharged, may be formed at a central part of the first plate portion <NUM>. The discharge opening <NUM> may be formed in one so as to be communicated with both of the first and second compression chambers (V1, V2). Alternatively, the discharge opening <NUM> may be formed in plurality so as to be communicated with the first and second compression chambers (V1, V2).

A second shaft accommodation portion <NUM>, configured to support a sub bearing portion <NUM> of the rotation shaft <NUM> to be explained later, may be formed at a central part of the first plate portion <NUM> of the fixed scroll <NUM>. A second shaft accommodating hole 326a, configured to support the sub bearing portion <NUM> in a radius direction, may be penetratingly-formed at the second shaft accommodating portion <NUM> in an axial direction.

A thrust bearing portion <NUM>, configured to support a lower end surface of the sub bearing portion <NUM> in an axial direction, may be formed at a lower end of the second shaft accommodation portion <NUM>. The thrust bearing portion <NUM> may protrude from a lower end of the second shaft accommodating hole 326a in a radius direction, towards a shaft center. However, the thrust bearing portion may be formed between a bottom surface of an eccentric portion <NUM> of the rotation shaft <NUM> to be explained later, and the first plate portion <NUM> of the fixed scroll <NUM> corresponding thereto.

A discharge cover <NUM>, configured to accommodate a refrigerant discharged from the compression chamber (V) therein and to guide the refrigerant to a refrigerant passage to be explained later, may be coupled to a lower side of the fixed scroll <NUM>. The discharge cover <NUM> may be formed such that an inner space thereof may accommodate therein the discharge opening <NUM> and may accommodate therein an inlet of the refrigerant passage (PG) along which a refrigerant discharged from the compression chamber (V1) is guided to the inner space 1a of the casing <NUM>.

The refrigerant passage (PG) may be penetratingly-formed at the second side wall portion <NUM> of the fixed scroll <NUM> and the first side wall portion <NUM> of the main frame <NUM>, sequentially, at an inner side of an oil passage separation portion <NUM>. Alternatively, the refrigerant passage (PG) may be formed so as to be consecutively recessed from an outer circumferential surface of the second side wall portion <NUM> and an outer circumferential surface of the first frame <NUM>.

The orbiting scroll <NUM> may be installed between the main frame <NUM> and the fixed scroll <NUM> so as to perform an orbiting motion. An Oldham's ring <NUM> for preventing a rotation of the orbiting scroll <NUM> may be installed between an upper surface of the orbiting scroll <NUM> and a bottom surface of the main frame <NUM> corresponding thereto, and a sealing member <NUM> which forms a back pressure chamber (S) may be installed at an inner side than the Oldham's ring <NUM>. Thus, the back pressure chamber (S) may be implemented as a space formed by the main frame <NUM>, the fixed scroll <NUM> and the orbiting scroll <NUM>, outside the sealing member <NUM>. The back pressure chamber (S) forms an intermediate pressure because a refrigerant of an intermediate pressure is filled therein as the back pressure chamber (S) is communicated with the intermediate compression chamber (V) by a back pressure hole 321a provided at the fixed scroll <NUM>. However, a space formed at an inner side than the sealing member <NUM> may also serve as a back pressure chamber as oil of high pressure is filled therein.

An orbiting plate portion (hereinafter, will be referred to as a second plate portion) <NUM> of the orbiting scroll <NUM> may be formed to have an approximate disc shape. The back pressure chamber (S) may be formed at an upper surface of the second plate portion <NUM>, and the orbiting wrap <NUM> which forms the compression chamber by being engaged with the fixed wrap <NUM> may be formed at a bottom surface of the second plate portion <NUM>.

The eccentric portion <NUM> of the rotation shaft <NUM> to be explained later may be rotatably inserted into a central part of the second plate portion <NUM>, such that a rotation shaft coupling portion <NUM> may pass therethrough in an axial direction.

The rotation shaft coupling portion <NUM> may be extended from the orbiting wrap <NUM> so as to form an inner end of the orbiting wrap <NUM>. Thus, since the rotation shaft coupling portion <NUM> is formed to have a height high enough to be overlapped with the orbiting wrap <NUM> on the same plane, the eccentric portion <NUM> of the rotation shaft <NUM> may be overlapped with the orbiting wrap <NUM> on the same plane. With such a configuration, a repulsive force and a compressive force of a refrigerant are applied to the same plane on the basis of the second plate portion to be attenuated from each other. This may prevent a tilted state of the orbiting scroll <NUM> due to the compressive force and the repulsive force.

An outer circumference of the rotation shaft coupling portion <NUM> is connected to the orbiting wrap <NUM> to form the compression chamber (V) during a compression operation together with the fixed wrap <NUM>. The orbiting wrap <NUM> may be formed to have an involute shape together with the fixed wrap <NUM>. However, the orbiting wrap <NUM> may be formed to have various shapes. For instance, as shown in <FIG>, the orbiting wrap <NUM> and the fixed wrap <NUM> may be formed to have a shape implemented as a plurality of circles of different diameters and origin points are connected to each other, and a curved line of an outermost side may be formed as an approximate oval having a long axis and a short axis.

A protrusion <NUM> protruded toward an outer circumference of the rotation shaft coupling portion <NUM>, is formed near an inner end (a suction end or a starting end) of the fixed wrap <NUM>. A contact portion 328a may be protruded from the protrusion <NUM>. That is, the inner end of the fixed wrap <NUM> may be formed to have a greater thickness than other parts. With such a configuration, the inner end of the fixed wrap <NUM>, having the largest compressive force among other parts of the fixed wrap <NUM>, may have an enhanced wrap intensity and may have enhanced durability.

A concaved portion <NUM>, engaged with the protrusion <NUM> of the fixed wrap <NUM>, is formed at an outer circumference of the rotation shaft coupling portion <NUM> which is opposite to the inner end of the fixed wrap <NUM>. A thickness increase portion 335a, having its thickness increased from an inner circumferential part of the rotation shaft coupling portion <NUM> to an outer circumferential part thereof, is formed at one side of the concaved portion <NUM>, at an upstream side in a direction to form the compression chambers (V). This may enhance a compression ratio of the first compression chamber (V1) by shortening a length of the first compression chamber (V1) prior to a discharge operation.

A circular arc surface 335b having a circular arc shape is formed at another side of the concaved portion <NUM>. A diameter of the circular arc surface 335b is determined by a thickness of the inner end of the fixed wrap <NUM> and an orbiting radius of the orbiting wrap <NUM>. If the thickness of the inner end of the fixed wrap <NUM>, the diameter of the circular arc surface 335b is increased. This may allow the orbiting wrap around the circular arc surface 335b to have an increased thickness and thus to obtain durability. Further, since a compression path becomes longer, a compression ratio of the second compression chamber (V2) may be increased in correspondence thereto.

The rotation shaft <NUM> may be supported in a radius direction as an upper part thereof is forcibly-coupled to a central part of the rotor <NUM>, and as a lower part thereof is coupled to the compression part <NUM>. Thus, the rotation shaft <NUM> transmits a rotational force of the motor part <NUM> to the orbiting scroll <NUM> of the compression part <NUM>. As a result, the orbiting scroll <NUM> eccentrically-coupled to the rotation shaft <NUM> performs an orbiting motion with respect to the fixed scroll <NUM>.

A main bearing portion <NUM>, supported in a radius direction by being inserted into the first shaft accommodating hole 312a of the main frame <NUM>, may be formed at a lower part of the rotation shaft <NUM>. And the sub bearing portion <NUM>, supported in a radius direction by being inserted into the second shaft accommodating hole 326a of the fixed scroll <NUM>, may be formed below the main bearing portion <NUM>. The eccentric portion <NUM>, inserted into the rotation shaft coupling portion <NUM> of the orbiting scroll <NUM>, may be formed between the main bearing portion <NUM> and the sub bearing portion <NUM>.

The main bearing portion <NUM> and the sub bearing portion <NUM> may be formed to be concentric with each other, and the eccentric portion <NUM> may be formed to be eccentric from the main bearing portion <NUM> or the sub bearing portion <NUM> in a radius direction. The sub bearing portion <NUM> may be formed to be eccentric from the main bearing portion <NUM>.

An outer diameter of the eccentric portion <NUM> may be preferably formed to be smaller than that of the main bearing portion <NUM> but to be larger than that of the sub bearing portion <NUM>, such that the rotation shaft <NUM> may be easily coupled to the eccentric portion <NUM> through the shaft accommodating holes 312a, 326a, and the rotation shaft coupling portion <NUM>. However, in case of forming the eccentric portion <NUM> using an additional bearing without integrally forming the eccentric portion <NUM> with the rotation shaft <NUM>, the rotation shaft <NUM> may be coupled to the eccentric portion <NUM>, without the configuration that the outer diameter of the eccentric portion <NUM> is larger than that of the sub bearing portion <NUM>.

An oil supply passage 5a, along which oil is supplied to the bearing portions and the eccentric portion, may be formed in the rotation shaft <NUM>. As the compression part <NUM> is disposed below the motor part <NUM>, the oil supply passage 5a may be formed in a chamfering manner from a lower end of the rotation shaft <NUM> to a lower end of the stator <NUM> or to an intermediate height of the stator <NUM>, or to a height higher than an upper end of the main bearing portion <NUM>.

An oil feeder <NUM>, configured to pump oil contained in the oil storage space 1b, may be coupled to a lower end of the rotation shaft <NUM>, i.e., a lower end of the sub bearing portion <NUM>. The oil feeder <NUM> may include an oil supply pipe <NUM> insertion-coupled to the oil supply passage 5a of the rotation shaft <NUM>, and an oil sucking member <NUM> (e.g., propeller) inserted into the oil supply pipe <NUM> and configured to suck oil. The oil supply pipe <NUM> may be installed to be immersed in the oil storage space 1b via a though hole <NUM> of the discharge cover <NUM>.

An oil supply hole and/or an oil supply groove, configured to supply oil sucked through the oil supply passage to an outer circumferential surface of each of the respective bearing portions and the eccentric portion, may be formed at the respective bearing portions and the eccentric portion, or at a position between the respective bearing portions. Thus, oil sucked toward an upper end of the main bearing portion <NUM> along the oil supply passage 5a of the rotation shaft <NUM>, an oil supply hole (not shown) and an oil supply groove (not shown), flows out of bearing surfaces from an upper end of the first shaft accommodating portion <NUM> of the main frame <NUM>. Then, the oil flows down onto an upper surface of the main frame <NUM>, along the first shaft accommodating portion <NUM>. Then, the oil is collected in the oil storage space 1b, through an oil passage (PO) consecutively formed on an outer circumferential surface of the main frame <NUM> (or through a groove communicated from the upper surface of the main frame <NUM> to the outer circumferential surface of the main frame <NUM>) and an outer circumferential surface of the fixed scroll <NUM>.

Further, oil, discharged to the inner space 1a of the casing <NUM> from the compression chamber (V) together with a refrigerant, is separated from the refrigerant at an upper space of the casing <NUM>. Then, the oil is collected in the oil storage space 1b, through a passage formed on an outer circumferential surface of the motor part <NUM>, and through the oil passage (PO) formed on an outer circumferential surface of the compression part <NUM>.

The lower compression type scroll compressor according to the present invention is operated as follows.

Firstly, once power is supplied to the motor part <NUM>, the rotor <NUM> and the rotation shaft <NUM> are rotated as a rotational force is generated. As the rotation shaft <NUM> is rotated, the orbiting scroll <NUM> eccentrically-coupled to the rotation shaft <NUM> performs an orbiting motion by the Oldham's ring <NUM>.

As a result, the refrigerant supplied from the outside of the casing <NUM> through the refrigerant suction pipe <NUM> is introduced into the compression chambers (V), and the refrigerant is compressed as a volume of the compression chambers (V) is reduced by the orbiting motion of the orbiting scroll <NUM>. Then, the compressed refrigerant is discharged to an inner space of the discharge cover <NUM> through the discharge opening <NUM>.

Then, the refrigerant discharged to the inner space of the discharge cover <NUM> circulates at the inner space of the discharge cover <NUM>, thereby having its noise reduced. Then, the refrigerant moves to a space between the main frame <NUM> and the stator <NUM>, and moves to an upper space of the motor part <NUM> through a gap between the stator <NUM> and the rotor <NUM>.

Then, the refrigerant has oil separated therefrom at the upper space of the motor part <NUM>, and then is discharged to the outside of the casing <NUM> through the refrigerant discharge pipe <NUM>. On the other hand, the oil is collected in the oil storage space, a lower space of the casing <NUM>, through a flow path between an inner circumferential surface of the casing <NUM> and the stator <NUM>, and through a flow path between the inner circumferential surface of the casing <NUM> and an outer circumferential surface of the compression part <NUM>. Such processes are repeatedly performed.

The compression chamber (V) formed between the fixed scroll <NUM> and the orbiting scroll <NUM> has a suction chamber at an edge region, and has a discharge chamber at a central region on the basis of the orbiting scroll <NUM>. As a result, the fixed scroll <NUM> and the orbiting scroll <NUM> have a highest temperature at the central region. This may cause the fixed scroll <NUM> and the orbiting scroll <NUM> to have severe thermal expansion at the central region. Especially, in a case where the orbiting scroll <NUM> is formed of a soft material such as aluminum, the orbiting scroll <NUM> may have larger thermal expansion than the fixed scroll <NUM> formed of cast-iron. Hereinafter, the orbiting scroll will be mainly explained.

<FIG> are an unfolded view and a planar view, respectively, which illustrate a wrap thickness in order to explain a partial interference between an orbiting scroll and a fixed scroll in the scroll compressor of <FIG>. due to thermal expansion of the orbiting scroll.

As shown in <FIG>, when a gap (G) between a fixed wrap <NUM> and an orbiting wrap <NUM> is constant as an orbiting radius, the orbiting wrap <NUM> and the fixed wrap <NUM> may be interfered with each other at a section. That is, if thermal expansion occurs at a central region of the orbiting scroll <NUM> having a discharge chamber, an edge region of the orbiting scroll <NUM> has a total expansion amount obtained by adding an expansion amount at the central region to an expansion amount at the edge region, since an expansion amount is sequentially accumulated from the central region to the edge region. This may cause an expansion amount to be increased toward the edge region.

Accordingly, as shown in <FIG>, the edge region may have a point where a side surface of the orbiting wrap <NUM> excessively contacts a side surface of the fixed wrap <NUM> corresponding thereto. This may cause a frictional loss between contact surfaces of the fixed wrap <NUM> and the orbiting wrap <NUM>. Especially, severe abrasion may occur on the contact surface of the orbiting wrap <NUM> formed of a soft material. This may cause the orbiting wrap <NUM> and the fixed wrap <NUM> to be widened from each other, resulting in refrigerant leakage and a compression loss.

In order to solve such problems, in this embodiment, a wrap interval (or wrap thickness) of the orbiting wrap is gradually increased from the central region toward the edge region. This may prevent interference between the orbiting wrap and the fixed wrap, even if the orbiting scroll has thermal expansion in a radius direction.

<FIG> is a planar view illustrating a state that a fixed scroll and an orbiting scroll are concentric with each other in a scroll compressor according to the present invention. And <FIG> is a sectional view taken along line 'V-V' in <FIG>, which is a longitudinal sectional view for explaining a wrap interval in a coupled state of a fixed scroll to an orbiting scroll.

As shown in <FIG>, in a state where a center (O) of the fixed scroll <NUM> and a center (O') of the orbiting scroll <NUM> are consistent with each other, an interval between the fixed wrap <NUM> and the orbiting wrap <NUM> will be explained. A wrap interval (G1) between an outer circumferential surface of a rotation shaft coupling portion <NUM> which forms a central region of the orbiting scroll <NUM> and a side surface of a neighboring innermost wrap may be smaller than wrap intervals (G2, G3) between the outer circumferential surface of the rotation shaft coupling portion <NUM> and neighboring outer wraps. In this case, the second wrap interval (G2) may be smaller than the third wrap interval (G3).

For this, a wrap thickness (t1) at the rotation shaft coupling portion <NUM> may be greater than a wrap thickness (t2) at a neighboring outer side of the rotation shaft coupling portion <NUM>. And the wrap thickness (t2) may be greater than a wrap thickness (t3) at an outer side of the rotation shaft coupling portion <NUM>. Accordingly, the wrap intervals (G1, G2, G3) may be increased toward the edge region of the orbiting scroll <NUM> from the central region. However, in some cases, the wrap intervals may be increased toward the edge region of the orbiting scroll from the central region, in a state where the wrap thicknesses are constant. Alternatively, the wrap intervals may be increased toward the edge region of the orbiting scroll from the central region, in a state where the wrap thicknesses are increased toward the edge region.

<FIG> is an unfolded view illustrating a wrap thickness from an upper side, in order to explain an embodiment to prevent a partial interference between an orbiting scroll and a fixed scroll in a scroll compressor according to the present invention.

As shown in <FIG>, the orbiting wrap <NUM> may be offset, such that widths (a1, a1) of two side surfaces 332a,332b on the basis of a center line (CL) of the orbiting wrap <NUM> may be decreased toward a suction chamber (Vs) from a discharge chamber (Vd). Accordingly, a wrap thickness (t) of the orbiting wrap <NUM> may be decreased toward a suction chamber side end 332d from a discharge chamber side end 332c.

Accordingly, as shown in <FIG>, the wrap intervals (G1, G2, G3) between the fixed wrap <NUM> and the orbiting wrap <NUM> may be gradually increased towards an edge region which forms a suction chamber, from a central region which forms a discharge chamber. That is, a wrap interval between the fixed wrap <NUM> and the orbiting wrap <NUM> may be formed as follows. A first wrap interval (G1) formed at a central region of the orbiting scroll <NUM> (or/and the fixed scroll) may be the same as an orbiting radius (r) of the orbiting scroll <NUM>. A second wrap interval (G2) formed between the central region and an edge region, and a third wrap interval (G3) formed at the edge region may be larger than the orbiting radius (r) of the orbiting scroll <NUM>. In this case, the third wrap interval (G3) may be larger than the second wrap interval (G2).

With such a configuration, even if thermal deformation of the orbiting wrap is accumulated in a radius direction (a wrap thickness direction) due to thermal expansion towards the edge region from the central region, a gap between the fixed wrap <NUM> and the orbiting wrap <NUM> at the edge region is sufficiently obtained. This may prevent an excessive contact between a side surface of the fixed wrap <NUM> and a side surface of the orbiting wrap <NUM> corresponding thereto.

Hereinafter, will be explained another embodiment to increase a wrap interval towards an edge region from a central region in a scroll compressor according to the present invention. <FIG> and <FIG> are unfolded views illustrating a wrap thickness from an upper side, in order to explain another embodiment to prevent a partial interference between an orbiting scroll and a fixed scroll in the scroll compressor of <FIG>.

As shown in <FIG>, only one side surface 332b of the two side surfaces of the orbiting wrap <NUM> may be offset (a2). However, in this case, another side surface which has not been offset may be interfered with a side surface of the fixed wrap <NUM>. In this case, the side surface of the fixed wrap <NUM> is also offset, preferably. This may prevent a significant decrease of a wrap thickness of the orbiting wrap <NUM> at a suction chamber side, thereby enhancing reliability.

As shown in <FIG>, like the orbiting wrap <NUM>, two side surfaces of the fixed wrap <NUM> may be offset (a31, a32), such that a wrap thickness may be decreased toward a suction chamber side end 323d from a discharge chamber side end 323c. As a result, a wrap interval (G) between the fixed wrap <NUM> and the orbiting wrap <NUM> may be gradually increased towards an edge region from a central region of the orbiting scroll <NUM> (or/and the fixed scroll). This may prevent a significant decrease of a wrap thickness of the orbiting wrap <NUM> at a suction chamber side, thereby enhancing reliability.

The orbiting wrap <NUM> has greater thermal expansion than the fixed wrap <NUM> even if the fixed wrap <NUM> and the orbiting wrap <NUM> are formed of the same material. Considering this, the fixed wrap <NUM> may be processed such that a wrap thickness thereof may be the same as that according to the original profile. On the other hand, the orbiting wrap <NUM> may be processed such that a wrap thickness thereof may be smaller than that according to the original profile. In a case where the orbiting scroll <NUM> is formed of aluminum whereas the fixed scroll <NUM> is formed of cast-iron, it is preferable to gradually decease the wrap thickness of the orbiting wrap <NUM> in a suction side direction, because a thermal expansion coefficient of aluminum is larger than that of cast-iron by two times approximately.

With such a configuration, interference between the fixed wrap and the orbiting wrap may be prevented, even if a thermal deformation is increased towards an edge region from a central region due to thermal expansion of the fixed scroll or the orbiting scroll while the scroll compressor is being operated, because a gap between the fixed wrap and the orbiting wrap is gradually increased toward the edge region. This may significantly reduce a frictional loss or abrasion due to interference between the fixed wrap and the orbiting wrap.

Claim 1:
A compressor, comprising:
a casing (<NUM>);
a drive motor (<NUM>) provided in the inner space of the casing;
a rotating shaft (<NUM>) coupled to the driving motor to rotate;
an orbiting scroll (<NUM>) including an orbiting plate portion (<NUM>) coupled to the rotating shaft (<NUM>) and an orbiting wrap (<NUM>) extending along a circumference direction of the orbiting plate portion;
a fixed scroll (<NUM>) comprising a fixed wrap (<NUM>) provided in engagement with the orbiting wrap to compress a refrigerant, a fixed plate portion (<NUM>) including a suction opening (<NUM>) receiving the refrigerant and a discharge opening (<NUM>) spaced apart from the suction opening to discharge the refrigerant;
wherein the orbiting scroll (<NUM>) further includes a rotation shaft coupling portion (<NUM>) coupled to the rotation shaft, wherein the orbiting wrap (<NUM>) is provided extending from the rotation shaft coupling portion (<NUM>) toward the case along the circumference of the orbiting plate portion,
wherein the rotation shaft coupling portion (<NUM>) is provided to be penetrated by the rotating shaft (<NUM>),
wherein the orbiting wrap (<NUM>) and the rotation shaft coupling portion (<NUM>) are disposed to be overlapped in height,
wherein a protrusion (<NUM>) protruded toward an outer circumference of the rotation shaft coupling portion (<NUM>), is formed near an inner end of the fixed wrap (<NUM>)
wherein the rotation shaft coupling portion (<NUM>) is provided to include a circular arc surface (335b) facing the protrusion (<NUM>),
wherein the orbiting wrap is provided to extend from the circular arc surface (335b),
wherein the thickness of the orbiting wrap (<NUM>) extended from the circular arc surface (335b) is thicker than the thickness of the orbiting wrap (<NUM>) facing the suction opening (<NUM>),
characterized in that thickness of the orbiting wrap (<NUM>) is provided to decrease as it extends from the discharge opening (<NUM>) toward the suction opening (<NUM>).