Rotary Compressor and Refrigeration Apparatus Including the Same

This is a continuation of International Application No. PCT/JP2024/012928 filed on Mar. 28, 2024, which claims priority under 35 U.S.C. § 119 (a) to Patent Application No. 2023-057770, filed in Japan on Mar. 31, 2023, all of which are hereby expressly incorporated by reference into the present application.

The present disclosure relates to a rotary compressor and a refrigeration apparatus including the rotary compressor.

Two-cylinder rotary compressors have been known as a rotary compressor. The two-cylinder rotary compressors are vertical compressors having a motor, a drive shaft, and a compression mechanism housed in a casing, and the axial direction of which along the axis of the drive shaft is the vertical direction. The motor is disposed above the compression mechanism. The drive shaft couples a rotor that constitutes the motor and the compression mechanism to each other.

The compression mechanism has two cylinders arranged one above the other, and eccentric portions housed in the respective cylinders. The two eccentric portions are eccentric with respect to the axis of the drive shaft with a phase difference of 180 degrees in the circumferential direction. The inside of each cylinder is divided into a high-pressure chamber and a low-pressure chamber by a blade extending outward in the radial direction from a piston. Each eccentric portion eccentrically rotates in the cylinder along with the rotation of the drive shaft. By this operation, the compression mechanism sucks fluid into the low-pressure chamber, changes the low-pressure chamber to the high-pressure chamber, and compresses the fluid in the high-pressure chamber.

In the two-cylinder rotary compressor, the rotor that constitutes the motor is provided with a balancer for compensating the unbalance due to the eccentric rotational motion of the compression mechanism. The balancer includes two balance weights provided on both upper and lower surfaces of the rotor. One example of such a rotary compressor with the balancer is disclosed in Japanese Unexamined Patent Publication No. 2009-180203.

A first aspect of the present disclosure is directed to a rotary compressor. The rotary compressor of the first aspect includes: a compression mechanism configured to suck and compress a fluid; a drive shaft configured to drive the compression mechanism; a motor having a rotor coupled to the drive shaft; and a balancer provided on the rotor. The compression mechanism has a first cylinder and a second cylinder sequentially arranged next to each other from a side closer to the rotor in an axial direction along an axis of the drive shaft, a first eccentric portion housed in the first cylinder, and a second eccentric portion housed in the second cylinder. The balancer has a first balance weight disposed at one end portion of the rotor closer to the compression mechanism in the axial direction, and a second balance weight disposed at the other end portion of the rotor in the axial direction. The first eccentric portion and the first balance weight are eccentric to the axis of the drive shaft to one side, and the second eccentric portion and the second balance weight are eccentric to the axis of the drive shaft to the other side. In the rotary compressor, along with rotation of the drive shaft, the first eccentric portion eccentrically rotates in the first cylinder, and the second eccentric portion eccentrically rotates in the second cylinder. A relationship of m1×r1>m2×r2 is satisfied, where a mass of the first balance weight is m1, an eccentric distance of a center of gravity of the first balance weight from the axis of the drive shaft is r1, a mass of the second balance weight is m2, and an eccentric distance of a center of gravity of the second balance weight from the axis of the drive shaft is r2.

An illustrative embodiment will be described below in detail with reference to the drawings. In the following embodiment, a case in which a rotary compressor according to the technique of the present disclosure is applied to a refrigeration apparatus will be described as an example. The drawings are used for conceptual description of the technique of the present disclosure. In the drawings, dimensions, ratios, or numbers may be exaggerated or simplified for easier understanding of the technique of the present disclosure.

In the following embodiment, a direction along the axis of a drive shaft of the rotary compressor will be referred to as an “axial direction,” a direction perpendicular to the axial direction as a “radial direction,” and a direction along the circumference of the drive shaft as a “circumferential direction.” In addition, the expressions of “first,” “second,” . . . are used to distinguish the terms to which these expressions are given, and do not limit the number and order of the terms.

As illustrated in, a rotary compressor () of this embodiment is provided in a refrigeration apparatus ().

The refrigeration apparatus () includes a refrigerant circuit (la). The refrigerant circuit (la) is filled with a refrigerant. The refrigerant is an example of the fluid compressed by the rotary compressor (). The refrigerant circuit (la) includes the rotary compressor (), a radiator (), a decompression mechanism (), and an evaporator (). The decompression mechanism () is an expansion valve, for example. The refrigerant circuit (la) performs a vapor compression refrigeration cycle.

In the refrigeration cycle, the gas refrigerant compressed by the rotary compressor () dissipates heat to the air in the radiator (). At this time, the refrigerant is liquefied and changed into liquid refrigerant. The liquid refrigerant having dissipated heat is decompressed by the decompression mechanism (). The decompressed liquid refrigerant is evaporated in the evaporator (). At this time, the refrigerant is vaporized and changed into gas refrigerant. The evaporated gas refrigerant is sucked into the rotary compressor (). The rotary compressor () compresses the sucked gas refrigerant.

The refrigeration apparatus () is an air conditioner, for example. The air conditioner may be a cooling and heating machine that switches between cooling and heating. In this case, the air conditioner has a switching mechanism that switches the direction of circulation of the refrigerant. The switching mechanism is a four-way switching valve, for example. The air conditioner may be a device for cooling only or a device for heating only.

The refrigeration apparatus () may be a water heater, a chiller unit, or a cooling apparatus that cools air in an internal space. The cooling apparatus is for cooling the air inside a water heater, a refrigerator, a freezer, or a container, for example.

As illustrated in, the rotary compressor () is a two-cylinder rotary compressor. The maximum number of rotations of the rotary compressor () is 120 rps or more. The maximum number of rotations described herein is the number of rotations of a drive shaft () rotated by the operation of a motor (), and refers to the maximum possible number of rotations in the operation range of the product. It is preferable to increase the maximum number of rotations of the rotary compressor () in order to increase the amount of circulation of the refrigerant in the refrigerant circuit (la) and ensure the maximum amount of circulation of the refrigerant.

The rotary compressor () includes a casing (), a drive mechanism (), a compression mechanism (), and a balancer (). The drive mechanism (), the compression mechanism (), and the balancer () are housed in the casing ().

The casing () is configured as a vertically-long cylindrical closed container with both ends closed. The casing () is placed in an upright position. The casing () has a barrel (), a lower end plate (), and an upper end plate (). The barrel () is in the shape of a cylinder extending in the vertical direction. The lower end plate () is fixed to the lower end of the barrel () to close the lower end opening of the barrel (). The upper end plate () is fixed to the upper end of the barrel () to close the upper end opening of the barrel ().

A suction pipe () is attached to a lower portion of the barrel (). The suction pipe () penetrates the barrel () and is connected to the compression mechanism (). A discharge pipe () is attached to the upper end plate (). The discharge pipe () penetrates the upper end plate () and is open to an upper space in the casing ().

An oil reservoir () is provided at the bottom of the casing (). The oil reservoir () is formed by inner walls of a lower portion of the barrel () and the lower end plate (). The oil reservoir () stores oil. The oil lubricates sliding portions of the compression mechanism () and the drive shaft ().

The drive mechanism () includes the motor () and the drive shaft (). The motor () is disposed above the compression mechanism (). The motor () includes a stator () and a rotor (). Each of the stator () and the rotor () has a cylindrical shape. The stator () is fixed to the barrel () of the casing (). The rotor () is disposed in the hollow of the stator ().

Circular plate-shaped end plates () having a hole are provided at both ends of the rotor () in the axial direction. The drive shaft () is inserted in the hollow of the rotor (). The rotor () is fixed to the drive shaft (). The drive shaft () rotates together with the rotor () when the motor () is energized. The drive shaft () is a shaft that drives the compression mechanism (), and extends in the vertical direction in the casing ().

The drive shaft () has a main shaft portion (), a first eccentric shaft portion (), and a second eccentric shaft portion (). An upper portion of the main shaft portion () is coupled to the rotor (). The first eccentric shaft portion () and the second eccentric shaft portion () are provided near the lower end of the main shaft portion (). The first eccentric shaft portion () is disposed above the second eccentric shaft portion (). The diameters of the first eccentric shaft portion () and the second eccentric shaft portion () are greater than the diameter of the main shaft portion ().

The first eccentric shaft portion () and the second eccentric shaft portion () are eccentric from the axis (AC) of the drive shaft () (main shaft portion ()) by a predetermined distance. The first eccentric shaft portion () and the second eccentric shaft portion () are eccentric with respect to the axis (AC) of the drive shaft () to the opposite sides. A portion of the main shaft portion () above the first eccentric shaft portion () is rotatably supported by a front head (). A portion of the main shaft portion () below the second eccentric shaft portion () is rotatably supported by a rear head ().

A first oil passage () is formed inside the drive shaft (). The first oil passage () extends to the sliding portions of the compression mechanism () and the drive shaft (). An oil supply pump () is provided at the lower end of the drive shaft (). The oil supply pump () is immersed in the oil in the oil reservoir (). The oil supply pump () delivers the oil along with rotation of the drive shaft (). The delivered oil is supplied to the sliding portions of the compression mechanism () and the drive shaft () through the first oil passage ().

The compression mechanism () is a mechanism for sucking and compressing the refrigerant, and is disposed below the motor (). The compression mechanism () includes the front head (), a first cylinder (), a middle plate (), a second cylinder (), and the rear head (). The front head (), the first cylinder (), the middle plate (), the second cylinder (), and the rear head () are stacked in this order from top to bottom and fixed with a fastening bolt ().

The front head () is fixed to the barrel () of the casing (). The front head () is stacked on the top of the first cylinder (). The front head () is disposed to cover a hollow (first cylinder bore ()) of the first cylinder () from above. The main shaft portion () of the drive shaft () is inserted into a center portion of the front head (). The front head () rotatably supports the drive shaft ().

The middle plate () is sandwiched between the first cylinder () and the second cylinder (). The middle plate () is disposed to cover the hollow (first cylinder bore ()) of the first cylinder () from below. The middle plate () is disposed to cover a hollow (second cylinder bore ()) of the second cylinder () from above.

The rear head () is stacked on the bottom of the second cylinder (). The rear head () is disposed to cover the hollow (second cylinder bore ()) of the second cylinder () from below. The main shaft portion () of the drive shaft () is inserted into a center portion of the rear head (). The rear head () rotatably supports the drive shaft ().

The first cylinder () is a substantially annular thick member. The first cylinder () has the first cylinder bore () at the center portion. The first cylinder bore () is a circular hole penetrating the first cylinder () in the thickness direction. The first cylinder bore () serves as a closed space defined by the front head () and the middle plate (). The first cylinder () is fixed to the barrel () of the casing () with the centerline of the first cylinder bore () extending in the axial direction (vertical direction).

As illustrated in, the first cylinder () has a first bush hole () and a first blade hole (). The first bush hole () and the first blade hole () penetrate the first cylinder () in the axial direction (thickness direction). The first bush hole () and the first blade hole () are each substantially in a circular shape. The first bush hole () is open to the first cylinder bore (). The first blade hole () is located outside the first bush hole () in the radial direction of the first cylinder (), and communicates with the first bush hole ().

A pair of first bushes () is fitted in the first bush hole (). Each of the first bushes () is a semi-cylindrical member. The flat surfaces of the pair of first bushes () face each other with a space therebetween. The pair of first bushes () can swing about the centerline of the first bush hole (). The pair of first bushes () sandwiches a first blade (), which will be described later, and restricts rotation of a first piston () on its own axis.

The first cylinder bore () houses the first piston (). The first piston () has a first roller () and the first blade (). The first roller () is a cylindrical member. The first eccentric shaft portion () of the drive shaft () is fitted in the first roller (). The outer peripheral surface of the first roller () is in sliding contact with the inner peripheral surface of the first cylinder ().

A space for compressing the refrigerant is formed between the outer peripheral surface of the first roller () and the inner peripheral surface of the first cylinder (). This space is a first compression chamber () formed by part of the first cylinder bore (). The first roller () rotates integrally with the first eccentric shaft portion (). The first roller () and the first eccentric shaft portion () form a first eccentric portion (). As described above, the compression mechanism () includes the first eccentric portion () housed in the first cylinder (). The first compression chamber () is formed between the inner peripheral surface of the first cylinder () and the first eccentric portion ().

The first blade () is provided on the outer peripheral surface of the first roller () and extends outward in the radial direction of the first roller (). The first blade () is sandwiched between the pair of first bushes () so as to be movable back and forth. A tip end portion of the first blade () is housed in the first blade hole (). The space between the outer peripheral surface of the first roller () and the inner peripheral surface of the first cylinder () is divided into a first low-pressure chamber and a first high-pressure chamber by the first blade ().

A first suction port () is formed in the first cylinder (). The first suction port () penetrates the first cylinder () in the radial direction. One end of the first suction port () is open in the inner peripheral surface of the first cylinder (), and communicates with the first low-pressure chamber at a position adjacent to the first bushes () (position on the right side of the first bushes () in). The other end of the first suction port () is open in the outer peripheral surface of the first cylinder (). The suction pipe () is connected to the other end of the first suction port ().

A first discharge port () is formed in the front head (). The first discharge port () penetrates the front head () in the axial direction. One end of the first discharge port () is open in the lower surface of the front head (), and communicates with the first high-pressure chamber at a position on the opposite side to the first suction port () with respect to the first bushes () (position on the left side of the first bushes () in). The other end of the first discharge port () is open in the upper surface of the front head ().

A first discharge valve () is provided on the upper surface of the front head (). The first discharge valve () opens and closes the first discharge port (). The first discharge valve () is, for example, a reed valve. The first discharge valve () is in a closed state closing the first discharge port () while a gas pressure in the first high-pressure chamber is lower than a gas pressure in the casing () (pressure inside the dome). The first discharge valve () is in an open state opening the first discharge port () when the gas pressure in the first high-pressure chamber exceeds the pressure inside the dome.

The second cylinder () is a substantially annular thick member. The second cylinder () has the second cylinder bore () at the center portion. The second cylinder bore () is a circular hole penetrating the second cylinder () in the thickness direction. The second cylinder bore () serves as a closed space defined by the middle plate () and the rear head (). The second cylinder () is provided with the centerline of the second cylinder bore () extending in the axial direction (vertical direction).

As illustrated in, the second cylinder () has a second bush hole () and a second blade hole (). The second bush hole () and the second blade hole () penetrate the second cylinder () in the axial direction (thickness direction). The second bush hole () and the second blade hole () are each substantially in a circular shape. The second bush hole () is open to the second cylinder bore (). The second blade hole () is located outside the second bush hole () in the radial direction of the second cylinder (), and communicates with the second bush hole ().

A pair of second bushes () is fitted in the second bush hole (). Each of the second bushes () is a semi-cylindrical member. The flat surfaces of the pair of second bushes () face each other with a space therebetween. The pair of second bushes () can swing about the centerline of the second bush hole (). The pair of second bushes () sandwiches a second blade (), which will be described later, and restricts rotation of a second piston () on its own axis.

The second cylinder bore () houses the second piston (). The second piston () has a second roller () and the second blade (). The second roller () is a cylindrical member. The second eccentric shaft portion () of the drive shaft () is fitted in the second roller (). The outer peripheral surface of the second roller () is in sliding contact with the inner peripheral surface of the second cylinder ().

A space for compressing the refrigerant is formed between the outer peripheral surface of the second roller () and the inner peripheral surface of the second cylinder (). This space is a second compression chamber () formed by part of the second cylinder bore (). The second roller () rotates integrally with the second eccentric shaft portion (). The second roller () and the second eccentric shaft portion () form a second eccentric portion (). As described above, the compression mechanism () includes the second eccentric portion () housed in the second cylinder (). The second compression chamber () is formed between the inner peripheral surface of the second cylinder () and the second eccentric portion ().

The second blade () is provided on the outer peripheral surface of the second roller () and extends outward in the radial direction of the second roller (). The second blade () is sandwiched between the pair of second bushes () so as to movable back and forth. A tip end portion of the second blade () is housed in the second blade hole (). The space between the outer peripheral surface of the second roller () and the inner peripheral surface of the second cylinder () is divided into a second low-pressure chamber and a second high-pressure chamber by the second blade ().

A second suction port () is formed in the second cylinder (). The second suction port () penetrates the second cylinder () in the radial direction. One end of the second suction port () is open in the inner peripheral surface of the second cylinder (), and communicates with the second low-pressure chamber at a position adjacent to the second bushes () (position on the right side of the second bushes () in). The other end of the second suction port () is open in the outer peripheral surface of the second cylinder (). The suction pipe () is connected to the other end of the second suction port ().

A second discharge port () is formed in the rear head (). The second discharge port () penetrates the rear head () in the axial direction. One end of the second discharge port () is open in the upper surface of the rear head (), and communicates with the second high-pressure chamber at a position on the opposite side to the second suction port () with respect to the second bushes () (position on the left side of the second bushes () in). The other end of the second discharge port () is open in the lower surface of the rear head ().

A second discharge valve () is provided on the lower surface of the rear head (). The second discharge valve () opens and closes the second discharge port (). The second discharge valve () is, for example, a reed valve. The second discharge valve () is in a closed state closing the second discharge port () while a gas pressure in the second high-pressure chamber is lower than the pressure inside the dome. The second discharge valve () is in an open state opening the second discharge port () when the gas pressure in the second high-pressure chamber exceeds the pressure inside the dome.

In the compression mechanism (), the first eccentric portion () eccentrically rotates in the first cylinder () along with the rotation of the drive shaft (). As the volume of the first low-pressure chamber gradually increases with eccentric rotation of the first eccentric portion (), the refrigerant flowing through the suction pipe () is sucked into the first low-pressure chamber through the first suction port (). Further eccentric rotation of the first eccentric portion () causes isolation of the first low-pressure chamber from the first suction port (), and the isolated space serves as the first high-pressure chamber.

The gas pressure in the first high-pressure chamber increases as the volume of the first high-pressure chamber gradually decreases along with further eccentric rotation of the first eccentric portion (). When the gas pressure in the first high-pressure chamber exceeds the pressure inside the dome, the first discharge valve () is opened, and the refrigerant in the first high-pressure chamber flows out of the compression mechanism () through the first discharge port ().

Along with rotation of the drive shaft (), the first eccentric portion () eccentrically rotates, and the second eccentric portion () also eccentrically rotates in the second cylinder (). As the volume of the second low-pressure chamber gradually increases with the eccentric rotation of the second eccentric portion (), the refrigerant flowing through the suction pipe () is sucked into the second low-pressure chamber through the second suction port (). Further eccentric rotation of the second eccentric portion () causes isolation of the second low-pressure chamber from the second suction port (), and the isolated space serves as the second high-pressure chamber.

The gas pressure in the second high-pressure chamber increases as the volume of the second high-pressure chamber gradually decreases along with further eccentric rotation of the second eccentric portion (). When the gas pressure in the second high-pressure chamber exceeds the pressure inside the dome, the second discharge valve () is opened, and the refrigerant in the second high-pressure chamber flows out of the compression mechanism () through the second discharge port ().

The high-pressure refrigerant having flowed out of the compression mechanism () flows upward in the internal space of the casing (), and passes through a core cut (not illustrated) or other portions of the motor (). Then, the high-pressure refrigerant having flowed upward of the motor () is transferred to the refrigerant circuit () through the discharge pipe ().