Rotary compressor

Abstract

[Problem] To provide a compressor that reliably prevents the stoppage of the rotational movement of a piston, and that has minimal impact with respect to mechanical loss. [Solution] Provided are: a cylinder (32) that defines a cylinder chamber (31); a crankshaft (15) that has an eccentric part (26) disposed inside the cylinder chamber (31); a piston (33) that is externally fitted over the eccentric part (26) and is disposed inside the cylinder chamber (31); and a vane (35) that is in contact with the piston (33) and partitions the cylinder chamber (31) into a suction chamber (31s) and a compression chamber (31c). The piston (33) comes into contact with the cylinder (32), at least once, while the crankshaft (15) rotates once.

Description

rotary compressor

[0001] An embodiment according to the present invention relates to a rotary compressor.

[0002] A rotary compressor includes an eccentric part that is eccentric to the center of the crankshaft, a piston that is fitted into the eccentric part and rotates along the inner surface of the cylinder, and a vane that protrudes into the cylinder chamber from a vane groove provided in the cylinder and comes into contact with the piston to divide the cylinder chamber into a suction chamber and a compression chamber. The piston revolves around the rotation centerline of the crankshaft along the inner surface of the cylinder while rotating around the eccentric part.

[0003] As the piston's revolution speed slows, it tends to become more difficult for the piston to rotate. When the crankshaft is rotating at low speeds, the piston's revolution speed slows. This can cause the piston to stop rotating. If the piston stops rotating and only revolves, the tip of the vane will continue to contact only a portion of the piston's outer periphery. This will cause abnormal wear to occur on that portion of the piston's outer periphery.

[0004] To address this issue, a rotary compressor is known that includes an eccentric part with a coating film that increases the friction between the outer circumferential surface of the eccentric part and the inner circumferential surface of the piston. The coating film covers a portion of the outer circumferential surface of the eccentric part in the circumferential direction. This coating film promotes the rotation of the piston when the crankshaft rotation speed is low, i.e., when the piston's orbital speed is low, and suppresses abnormal piston wear.

[0005] The piston is also called a roller.

[0006] JP 2022-56590 A

[0007] Conventional rotary compressors have a coating film on a part of the eccentric portion to promote the rotational movement of the piston.

[0008] However, the coating film on the eccentric portion increases the sliding resistance between the eccentric portion and the piston, resulting in an increase in mechanical loss in the compression mechanism. Furthermore, in conventional rotary compressors, it is difficult to avoid the increase in costs involved in forming the coating film on the eccentric portion.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a compressor that reliably prevents the rotational motion of the piston from stopping and that has little effect on mechanical loss.

[0010] In order to solve the above-mentioned problems, a rotary compressor according to an embodiment of the present invention includes a cylinder that defines a cylinder chamber, a crankshaft having an eccentric portion that is disposed within the cylinder chamber, a piston that is disposed within the cylinder chamber and fitted onto the eccentric portion, and a vane that comes into contact with the piston and divides the cylinder chamber into a suction chamber and a compression chamber, and the piston comes into contact with the cylinder at least once during one rotation of the crankshaft.

[0011] The present invention relates to a refrigeration cycle device and a compressor according to an embodiment of the present invention. The present invention relates to a compressor having a compression mechanism, a crankshaft, an eccentric portion, and a cylinder ... refrigeration cycle device, a compressor according to an embodiment of the present invention. The present invention relates to a compressor having a compression mechanism, a refrigeration cycle device, a compressor. The present invention relates to a compressor having a compression mechanism, a refrigeration cycle device, a compressor. The present invention relates to a compressor having a compression mechanism, a refrigeration cycle device, a compressor.

[0012] An embodiment of a compressor according to the present invention will be described with reference to Figures 1 to 4. Note that the same or corresponding components are designated by the same reference numerals throughout the drawings.

[0013] FIG. 1 is a schematic diagram of a refrigeration cycle device and a compressor according to an embodiment of the present invention.

[0014] As shown in Fig. 1, the refrigeration cycle apparatus 1 according to this embodiment includes a hermetic rotary compressor 2, a radiator 3, an expansion device 5, a heat absorber 6, an accumulator 7, and a refrigerant pipe 8. The refrigerant pipe 8 sequentially connects the compressor 2, the radiator 3, the expansion device 5, the heat absorber 6, and the accumulator 7, allowing the refrigerant to flow through the refrigeration cycle apparatus 1. The refrigerant flowing through the refrigeration cycle apparatus 1 is, for example, carbon dioxide. The refrigerant may be a refrigerant other than carbon dioxide, for example, R32 refrigerant.

[0015] The rotary compressor 2 (hereinafter simply referred to as “compressor 2”) sucks in the refrigerant that has passed through the heat absorber 6 through the refrigerant pipe 8, compresses it, and discharges the high-temperature, high-pressure refrigerant through the refrigerant pipe 8 to the radiator 3.

[0016] The compressor 2 comprises a cylindrical sealed container 11 that is placed vertically, an electric motor 12 that is arranged in the upper half of the sealed container 11, a compression mechanism section 13 that is arranged in the lower half of the sealed container 11, a crankshaft 15 that transmits the rotational driving force of the electric motor 12 to the compression mechanism section 13, a main bearing 16 that rotatably supports the crankshaft 15, and an auxiliary bearing 17 that cooperates with the main bearing 16 to rotatably support the crankshaft 15.

[0017] The sealed container 11 comprises a cylindrical body 11a extending in the vertical direction, a hemispherical or elliptical mirror plate 11b that closes the upper end of the body 11a, and a hemispherical or elliptical mirror plate 11c that closes the lower end of the body 11a.

[0018] The upper end plate 11b of the sealed container 11 is provided with a discharge pipe 8d for discharging the refrigerant. The discharge pipe 8d is connected to the refrigerant piping 8. The upper end plate 11b of the sealed container 11 is also provided with a sealed terminal portion 18 for supplying power. The body portion 11a is provided with a suction pipe 8s for suctioning the refrigerant, which is connected to the compression mechanism portion 13.

[0019] The electric motor 12 generates a driving force that rotates the compression mechanism 13. The electric motor 12 is, for example, a permanent magnet synchronous motor (PMSM). The electric motor 12 includes a cylindrical stator 21 fixed to the inner wall of the sealed container 11, a rotor 22 disposed inside the stator 21 and fixed to the crankshaft 15, and a plurality of lead wires 23 that are drawn from the stator 21 and connected to the sealed terminal 18.

[0020] The rotor 22 includes a rotor core 25 having magnet accommodating holes (not shown) and permanent magnets accommodated in the magnet accommodating holes. The rotor 22 is rotatable relative to the stator 21 and is supported by the crankshaft 15. The rotational center line C of the rotor 22 and the crankshaft 15 substantially coincides with the center line P of the stator 21.

[0021] The plurality of output wires 23 are wirings that supply power to the stator 21 through the sealed terminal portions 18, and are so-called lead wires. A plurality of output wires 23 are wired depending on the type of the electric motor 12. When the output wires 23 are used in an open winding type, two wires are wired for each of the U phase, V phase, and W phase, that is, a total of six output wires 23. When the electric motor 12 is used in a star connection, one wire is wired for each of the U phase, V phase, and W phase, that is, a total of three output wires 23.

[0022] The crankshaft 15 connects the electric motor 12 and the compression mechanism 13. The crankshaft 15 transmits the rotational driving force generated by the electric motor 12 to the compression mechanism 13.

[0023] An intermediate portion 15a of the crankshaft 15 connects the electric motor 12 and the compression mechanism 13 and is rotatably supported by a main bearing 16. A lower end portion 15b of the crankshaft 15 is rotatably supported by an auxiliary bearing 17. The main bearing 16 and the auxiliary bearing 17 are also part of the compression mechanism 13. In other words, the crankshaft 15 passes through the compression mechanism 13.

[0024] The crankshaft 15 also has an eccentric portion 26 between the middle portion 15a supported by the main bearing 16 and the lower end portion 15b supported by the sub-bearing 17. The eccentric portion 26 is a disk or a cylinder having a center that does not coincide with the rotational centerline of the crankshaft 15.

[0025] The compression mechanism 13 can compress a refrigerant, i.e., a single refrigerant or a mixed refrigerant. When the electric motor 12 rotates the crankshaft 15, the compression mechanism 13 draws in the gaseous refrigerant from the suction pipe 8s, compresses it, and discharges it into the sealed container 11.

[0026] The compression mechanism 13 includes a cylinder 32 having a circular cylinder chamber 31, an annular rolling piston 33 (hereinafter simply referred to as "piston 33") disposed within the cylinder chamber 31, and a vane 35 that reciprocates in contact with the outer peripheral surface of the piston 33 and separates the cylinder chamber 31 into a suction chamber and a compression chamber.

[0027] The cylinder 32 has an inner circumferential surface that defines the cylinder chamber 31. The cylinder 32 has an annular, plate-like shape with the cylinder chamber 31 inside. The cylinder 32 has an end face closer to the electric motor 12 and an end face farther from the electric motor 12. The cylinder 32 is fixed to the sealed container 11 at multiple locations by welding, for example, spot welding. The cylinder 32 has a suction hole (not shown) that is connected to the suction pipe 8s and reaches the cylinder chamber 31. The suction hole penetrates from the outer circumferential surface of the cylinder 32 to the inner circumferential surface of the cylinder 32.

[0028] The cylinder chamber 31 is the space inside the cylinder 32. The cylinder chamber 31 is a circular hole that penetrates the cylinder 32 in a direction along the center line of the crankshaft 15. In other words, the cylinder chamber 31 has an opening closer to the electric motor 12 and an opening farther from the electric motor 12. The cylinder chamber 31 is closed by the main bearing 16 and the sub bearing 17. The cylinder chamber 31 accommodates the eccentric portion 26 of the crankshaft 15.

[0029] The main bearing 16 is assembled to the cylinder 32 to close the cylinder chamber 31. The main bearing 16 is assembled to the end face of the cylinder 32 closer to the electric motor 12 to close the opening of the cylinder chamber 31 closer to the electric motor 12. The main bearing 16 is fixed to the cylinder 32 with fastening members 38 such as bolts. The compression mechanism 13 includes a discharge valve mechanism (not shown) that is provided to the main bearing 16 and discharges the refrigerant compressed in the cylinder chamber 31, and a discharge muffler 37 that covers the discharge valve mechanism. When the pressure difference between the pressure in the cylinder chamber 31 and the pressure in the discharge muffler 37 reaches a predetermined value due to the compression action of the compression mechanism 13, the discharge valve mechanism opens the discharge port to discharge the compressed refrigerant into the discharge muffler 37. The discharge muffler 37 has a discharge hole (not shown) that connects the inside and outside of the discharge muffler 37. The compressed refrigerant discharged into the discharge muffler 37 is discharged into the sealed container 11 through the discharge hole.

[0030] The auxiliary bearing 17 is combined with the cylinder 32 to close the cylinder chamber 31. The auxiliary bearing 17 is combined with the end face of the cylinder 32 farther from the electric motor 12 to close the opening of the cylinder chamber 31 farther from the electric motor 12. The auxiliary bearing 17 is fixed to the cylinder 32 by a fastening member 38 such as a bolt.

[0031] The piston 33 is fitted onto the circumferential surface of the eccentric portion 26. In other words, the piston 33 is fitted onto the outside of the eccentric portion 26. The outer circumferential surface of the piston 33 is in line contact with the inner circumferential surface of the cylinder chamber 31. As the crankshaft 15 rotates, the piston 33 revolves around the rotation center line C of the crankshaft 15 while keeping its outer circumferential surface in line contact with the inner circumferential surface of the cylinder chamber 31. This revolving motion of the piston 33 is also called eccentric motion. The motion of the piston 33 rotating around the eccentric portion 26 is called rotational motion of the piston 33.

[0032] The piston 33 and the cylinder 32 do not make direct contact but make indirect contact via an oil film (not shown) of refrigeration oil 39, but for ease of explanation, this contact via the oil film will be simply referred to as "contact." The same applies to the contact between the piston 33 and the eccentric portion 26, between the piston 33 and the main bearing 16, and between the piston 33 and the sub-bearing 17.

[0033] The suction pipe 8 s passes through the sealed container 11 and is connected to the cylinder chamber 31 via the suction hole of the cylinder 32 .

[0034] The lower part of the sealed container 11 is filled with refrigerating machine oil 39. Most of the compression mechanism 13 is immersed in the refrigerating machine oil 39 inside the sealed container 11.

[0035] FIG. 2 is a schematic cross-sectional view of a compression mechanism of a compressor according to an embodiment of the present invention.

[0036] The cross-sectional position of Fig. 2 includes the rotational center line C of the crankshaft 15 and the center line Cc of the eccentric portion 26. In other words, Fig. 2 is a cross section including the eccentric direction of the eccentric portion 26 as viewed from the rotational center line C of the crankshaft 15. Here, the "eccentric direction" refers to the direction from the rotational center line C of the crankshaft 15 toward the center line Cc of the eccentric portion 26.

[0037] 2, the compression mechanism 13 of the compressor 2 according to this embodiment has a gap between the piston 33 and the cylinder 32, a gap between the piston 33 and the eccentric portion 26, a gap between the crankshaft 15 and the main bearing 16, and a gap between the crankshaft 15 and the sub-bearing 17. When the crankshaft 15 is rotating, the refrigerating machine oil 39 tries to homogenize these gaps over the entire circumference of the crankshaft 15 and the entire circumference of the eccentric portion 26.

[0038] Therefore, in order to clearly define the relationship between these gaps, it is assumed that the crankshaft 15 and the main bearing 16 are pressed down so that the gap δ1 between the piston 33 and the cylinder 32 of the compressor 2 according to this embodiment is maximized, and that the eccentric portion 26 is pressed down against the piston 33, as shown in Figure 2. For ease of explanation, the state in which the piston 33, the cylinder 32, the crankshaft 15, and the main bearing 16 are arranged as shown in Figure 2 will be referred to as the "maximum gap δ1 state."

[0039] For ease of explanation, the description will be given assuming that the rotational center line C of the crankshaft 15 coincides with the center of the circular cylinder chamber 31 .

[0040] The maximum gap δ1 state occurs when, for example, the cylinder 32 is fixed, the main bearing 16 is temporarily fixed to the cylinder 32, the crankshaft 15 is pressed against the main bearing 16, and the piston 33 is pressed against the eccentric portion 26. At this time, the piston 33 contacts the peripheral surface 26o of the eccentric portion 26 at a position farthest from the rotation center line C of the crankshaft 15, and the crankshaft 15 contacts the main bearing 16 at a position 180 degrees opposite from the contact position between the piston 33 and the eccentric portion 26.

[0041] The gap δ2 between the piston 33 and the eccentric portion 26 appears at a position 180 degrees opposite from the contact position between the piston 33 and the eccentric portion 26, and the gap δ3 between the crankshaft 15 and the main bearing 16 appears at a position 180 degrees opposite from the contact position between the crankshaft 15 and the main bearing 16. In other words, the gap δ1 between the piston 33 and the cylinder 32 and the gap δ3 between the crankshaft 15 and the main bearing 16 appear on one side of the rotation center line C of the crankshaft 15, and the gap δ2 between the piston 33 and the eccentric portion 26 appears on the other side of the rotation center line C of the crankshaft 15.

[0042] Therefore, the gap δ1 between the piston 33 and the cylinder 32 corresponds to the maximum gap between the piston 33 and the cylinder 32 when the gap δ1 is at its maximum, the gap δ2 between the piston 33 and the eccentric portion 26 corresponds to the maximum gap between the piston 33 and the eccentric portion 26 when the gap δ1 is at its maximum, and the gap δ3 between the crankshaft 15 and the main bearing 16 corresponds to the maximum gap between the crankshaft 15 and the main bearing 16 when the gap δ1 is at its maximum.

[0043] The gap δ1 between the piston 33 and the cylinder 32 is the distance between the outer peripheral surface 33o of the piston 33 and the inner peripheral surface 32i of the cylinder 32 at the closest point when the gap δ1 is at its maximum. The gap δ2 between the piston 33 and the eccentric portion 26 is the distance between the inner peripheral surface 33i of the piston 33 and the peripheral surface 26o of the eccentric portion 26 at the farthest point when the gap δ1 is at its maximum. The gap δ3 between the crankshaft 15 and the main bearing 16 is the distance between the peripheral surface 15o of the crankshaft 15 and the inner peripheral surface 16i of the main bearing 16 at the farthest point when the gap δ1 is at its maximum. The gaps δ1, δ2, and δ3 are shown enlarged in all figures for ease of explanation.

[0044] In the rotary compressor 2, the piston 33 tends to become less able to rotate as the revolution speed of the piston 33 slows down. When the crankshaft 15 rotates slowly and the pressure difference between the suction pressure of the refrigerant and the discharge pressure of the refrigerant is large, the rotation of the piston 33 may stop.

[0045] If the piston 33 stops rotating and only revolves, the vane 35 will continue to contact the same location on the outer peripheral surface 33o of the piston 33. This may result in the appearance of streaky wear marks on the outer peripheral surface 33o of the piston 33. If the vane 35 gets caught on the wear marks, the piston 33 will stop rotating again, and the wear marks will expand. Even if the vane 35 does not get caught on the wear marks, it may generate abnormal noise as it passes over the wear marks, or the vane 35 may bounce up and separate from the piston 33, ultimately reducing the functionality of the compression mechanism 13.

[0046] Therefore, the compressor 2 according to this embodiment is provided with a piston 33 that contacts the cylinder 32 at least once per rotation of the crankshaft 15. In other words, per rotation of the crankshaft 15, the outer peripheral surface 33o of the piston 33 contacts the inner peripheral surface 32i of the cylinder 32 at least once. This causes frictional force acting between the piston 33 and the cylinder 32 that are in contact, forcing the piston 33 to rotate on its axis. The forced rotation of the piston 33 constantly changes the contact point between the vane 35 and the outer peripheral surface 33o of the piston 33 in the circumferential direction of the piston 33. This change in the contact point prevents wear marks from occurring on the outer peripheral surface 33o of the piston 33.

[0047] FIG. 3 is a schematic plan view of the crankshaft, the eccentric portion, and the cylinder of the compressor according to the embodiment of the present invention.

[0048] Here, the crank angle θ of the crankshaft 15 and the eccentric portion 26 is defined as 0 degrees when the eccentric direction of the eccentric portion 26 overlaps with the direction of advancement and retreat of the vane 35 relative to the cylinder chamber 31, and a positive crank angle θ is defined in the rotational direction of the crankshaft 15 and the eccentric portion 26. The crank angle θ is also called the rotation angle. A crank angle θ of 0 degrees is called top dead center (TDC), and a crank angle θ of 180 degrees is called bottom dead center (BDC).

[0049] 3 illustrates a range in which the crank angle θ is greater than 0 degrees and equal to or less than 180 degrees (0 degrees<crank angle θtb≦180 degrees). In other words, FIG. 3 illustrates a case in which the crankshaft 15 is positioned at a crank angle θtb from after top dead center (ATDC) to bottom dead center.

[0050] At a crank angle θtb at which the crankshaft 15 moves from top dead center to bottom dead center, the gap δ1 between the piston 33 and the cylinder 32, the gap δ2 between the piston 33 and the eccentric portion 26, and the gap δ3 between the crankshaft 15 and the main bearing 16 are set within the range (third range) expressed by [Equation 1].

[0051] [Equation 1] ((gap δ2 + gap δ3) ÷ 2 × 0.5) ≦ (gap δ1) ≦ ((gap δ2 + gap δ3) ÷ 2)

[0052] The relationship between the gaps δ1, δ2, and δ3 expressed by [Equation 1] is such that the piston 33 comes into contact with the cylinder 32 at least once per one rotation of the crankshaft 15 when the compression mechanism 13 rotates under no load, ignoring the suction and compression of the refrigerant, and the gap between the piston 33 and the eccentric portion 26 is made uniform in the circumferential direction, and the gap between the crankshaft 15 and the main bearing 16 is made uniform in the circumferential direction.

[0053] Furthermore, at a crank angle θtb where the crankshaft 15 moves from top dead center to bottom dead center, a force Fc acting on the piston 33 from the compressed refrigerant moves the piston 33 closer to the cylinder 32. Therefore, the relationship between the gaps δ1, δ2, and δ3 expressed by [Equation 1] ensures that the piston 33 comes into contact with the cylinder 32 at least once during one rotation of the crankshaft 15.

[0054] Furthermore, the relationship between the clearances δ1, δ2, and δ3 expressed by [Equation 1] absorbs various tolerances, including dimensional tolerances and assembly tolerances, of the crankshaft 15, eccentric portion 26, piston 33, main bearing 16, and cylinder 32, and prevents the crankshaft 15 from mechanically locking (becoming unable to rotate).

[0055] However, if the rotational center line C of the crankshaft 15 does not coincide with the center of the circular cylinder chamber 31, but is offset, for example, toward the compression chamber 31c or the suction chamber 31s of the cylinder chamber 31, the gap δ1 between the piston 33 and the cylinder 32 changes from moment to moment as the crank angle θ of the crankshaft 15 changes.

[0056] Therefore, if the rotational center line C of the crankshaft 15 does not coincide with the center of the circular cylinder chamber 31, but is arranged offset toward the suction chamber 31s side of the cylinder chamber 31, for example, at the crank angle θtb at which the crankshaft 15 moves from top dead center to bottom dead center, the relationship between the gaps δ1, δ2, and δ3 should be set within the range (first range) of [Equation 2] at the crank angle θtb_min at which the gap δ1 between the piston 33 and the cylinder 32 is smallest.

[0057] [Mathematical formula 2] ((gap δ2 + gap δ3) ÷ 2 × 0.5) ≦ (minimum gap δ1) ≦ ((gap δ2 + gap δ3) ÷ 2)

[0058] The relationship between the gaps δ1, δ2, and δ3 expressed by [Equation 2] allows the piston 33 to come into contact with the cylinder 32 at least once during one rotation of the crankshaft 15, even if the rotational center line C of the crankshaft 15 is offset toward the suction chamber 31s side of the cylinder chamber 31.

[0059] FIG. 4 is a schematic plan view of the crankshaft, the eccentric portion, and the cylinder of the compressor according to the embodiment of the present invention.

[0060] 4 illustrates a range in which the crank angle θ is greater than 180 degrees and less than or equal to 360 degrees (180 degrees<crank angle θbt≦360 degrees). In other words, FIG. 4 illustrates a case in which the crankshaft 15 is positioned at a crank angle θbt after bottom dead center (ABDC) until top dead center.

[0061] At a crank angle θbt at which the crankshaft 15 moves from bottom dead center to top dead center, the gap δ1 between the piston 33 and the cylinder 32, the gap δ2 between the piston 33 and the eccentric portion 26, and the gap δ3 between the crankshaft 15 and the main bearing 16 are set within a range (fourth range) expressed by [Equation 3].

[0062] [Mathematical Expression 3] ((Gap δ2 + Gap δ3) ÷ 2 × 0.2) ≦ (Gap δ1) ≦ ((Gap δ2 + Gap δ3) ÷ 2 × 0.8)

[0063] The relationship between the gaps δ1, δ2, and δ3 expressed by [Equation 3] is such that the piston 33 comes into contact with the cylinder 32 at least once per one rotation of the crankshaft 15 when the compression mechanism 13 rotates under no load, ignoring the suction and compression of the refrigerant, and the gap between the piston 33 and the eccentric portion 26 is made uniform in the circumferential direction, and the gap between the crankshaft 15 and the main bearing 16 is made uniform in the circumferential direction.

[0064] Furthermore, at a crank angle θbt where the crankshaft 15 moves from bottom dead center to top dead center, a force Fc acting on the piston 33 from the compressed refrigerant moves the piston 33 away from the cylinder 32. Therefore, the relationship between the clearances δ1, δ2, and δ3 expressed in [Equation 3] ensures that the piston 33 comes into contact with the cylinder 32 at least once per rotation of the crankshaft 15 by using the refrigerating machine oil 39 to keep the eccentricity between the crankshaft 15 and the main bearing 16 and the eccentricity between the piston 33 and the eccentric portion 26 at 20 percent or less. Note that the eccentricity is a value obtained by dividing the amount of eccentricity from the geometric center by the clearance.

[0065] Furthermore, the relationship between the clearances δ1, δ2, and δ3 expressed by [Equation 3] absorbs various tolerances, including dimensional tolerances and assembly tolerances, of the crankshaft 15, eccentric portion 26, piston 33, main bearing 16, and cylinder 32, preventing mechanical locking (unable to rotate) of the crankshaft 15. The range of [Equation 2] has a smaller lower limit value for the clearance δ1 than the range of [Equation 1]. This takes into consideration the action of force Fc that moves the piston 33 away from the cylinder 32.

[0066] Furthermore, if the rotational center line C of the crankshaft 15 does not coincide with the center of the circular cylinder chamber 31, but is arranged offset toward the compression chamber 31c of the cylinder chamber 31, for example, then at the crank angle θbt at which the crankshaft 15 moves from bottom dead center to top dead center, the relationship between the gaps δ1, δ2, and δ3 should be set within the range (first range) of [Equation 4] at the crank angle θbt_min at which the gap δ1 between the piston 33 and the cylinder 32 is smallest.

[0067] [Mathematical Formula 4] ((Gap δ2 + Gap δ3) ÷ 2 × 0.2) ≦ (Minimum Gap δ1) ≦ ((Gap δ2 + Gap δ3) ÷ 2 × 0.8)

[0068] The relationship between the gaps δ1, δ2, and δ3 expressed by [Equation 4] allows the piston 33 to come into contact with the cylinder 32 at least once during one rotation of the crankshaft 15, even if the rotational center line C of the crankshaft 15 is offset toward the compression chamber 31c of the cylinder chamber 31.

[0069] The piston 33 of the compressor 2 according to this embodiment only needs to come into contact with the cylinder 32 at least once during one rotation of the crankshaft 15. Therefore, the gap δ1 may deviate from the range of [Equation 4] as long as it is set within the range of [Equation 2]. Furthermore, the gap δ1 may deviate from the range of [Equation 2] as long as it is set within the range of [Equation 4]. In this way, the frictional force acting between the piston 33 and the cylinder 32 in contact reliably and forcibly rotates the piston 33 on its axis.

[0070] When the rotational center line C of the crankshaft 15 coincides with the center of the cylinder chamber 31, the gap δ1 may be set within the range of [Equation 1] at the crank angle θtb at which the crankshaft 15 moves from top dead center to bottom dead center, and the gaps δ1, δ2, and δ3 may have a relationship set within the range of [Equation 2] at the crank angle θbt at which the crankshaft 15 moves from bottom dead center to top dead center.

[0071] The hardness of the piston 33 is preferably greater than the hardness of the cylinder 32. Here, the difference in hardness is preferably evaluated by, for example, Rockwell hardness.

[0072] If the compressor 2 were to draw in and compress liquid refrigerant, there is a risk that the piston 33 would come into contact with or collide with the cylinder 32 more violently than expected. If the piston 33 were to wear or be damaged in such a case, problems would arise in the sliding portion between the vane 35 and the piston 33 during subsequent operation of the compressor 2. Therefore, by setting the hardness of the piston 33 to be greater than the hardness of the cylinder 32, the piston 33 can be protected from wear or damage. This ensures the integrity of the sliding portion between the vane 35 and the piston 33 during subsequent operation of the compressor 2.

[0073] However, if the hardness of the piston 33 is too high, there is a risk that the piston 33 will crack or chip when the cylinder 32 and the piston 33 collide. If the hardness of the cylinder 32 is too high, the piston 33 will be damaged when the cylinder 32 and the piston 33 collide, and if the hardness of the cylinder 32 is too low, the cylinder 32 will be worn by the vane 35.

[0074] Therefore, it is preferable that the Rockwell hardness of the piston 33 is HRC40 to HRC55, and the Rockwell hardness of the cylinder 32 is HRB80 to HRB100.

[0075] The piston 33 is made of, for example, Ni-Cr-Mo flake graphite cast iron, also known as Monichrome cast iron. The flake graphite provides excellent friction characteristics, while the dispersed carbon phosphides provide excellent wear resistance. The piston 33 may also be made of spheroidal graphite cast iron (ductile cast iron, nodular cast iron) specified in JIS G 5502. The cylinder 32 is made of, for example, gray cast iron, FC250 specified in JIS G 5501.

[0076] By appropriately selecting the hardness of the piston 33 and the hardness of the cylinder 32, the piston 33 is more reliably protected from wear or damage, and a sound sliding state between the piston 33 and the vane 35 is more reliably ensured.

[0077] Furthermore, the compressor 2 according to this embodiment is preferable for applications in which a refrigerant that needs to be compressed to a high pressure, such as carbon dioxide, is used. For example, when carbon dioxide is used as the refrigerant, the back pressure of the vane 35, i.e., the force pressing the vane 35 against the piston 33, increases. When the back pressure of the vane 35 increases, the rotational motion of the piston 33 tends to stop. The compressor 2 according to this embodiment forcibly rotates the piston 33 by using the frictional force acting between the piston 33 and the cylinder 32 in contact with each other, thereby preventing the rotational motion of the piston 33 from stopping even when the refrigerant needs to be compressed to a high pressure, such as carbon dioxide.

[0078] Furthermore, in the compressor 2 according to this embodiment, it is preferable that polyalkylene glycol oil is sealed in the sealed container 11 as the refrigerating machine oil 39. Polyalkylene glycol oil exhibits good lubricating performance even when carbon dioxide is used as the refrigerant. In other words, even when the compressor 2 is used to compress a refrigerant that needs to be compressed to a high pressure, such as carbon dioxide, it is possible to prevent problems, including seizure, caused by contact of the piston 33 with the cylinder 32.

[0079] As described above, the compressor 2 according to this embodiment includes the piston 33 that comes into contact with the cylinder 32 at least once during one rotation of the crankshaft 15. Therefore, the compressor 2 forces the piston 33 to rotate on its axis during one rotation of the crankshaft 15, constantly changing the contact points between the vane 35 and the piston 33, thereby preventing wear marks from occurring on the outer circumferential surface 33o of the piston 33.

[0080] Furthermore, the compressor 2 according to this embodiment has a minimum gap δ1 between the piston 33 and the cylinder 32 that is set within the range of [Equation 2] at the crank angle θtb_min at which the crankshaft 15 moves from top dead center to bottom dead center. Therefore, even if the rotational center line C of the crankshaft 15 does not coincide with the center of the cylinder chamber 31, the compressor 2 can reliably bring the piston 33 into contact with the cylinder 32 at least once during one rotation of the crankshaft 15, thereby forcing the piston 33 to rotate about its own axis, and prevents mechanical locking of the crankshaft 15 due to contact between the piston 33 and the cylinder 32.

[0081] Furthermore, the compressor 2 according to this embodiment has a minimum gap δ1 between the piston 33 and the cylinder 32 that is set within the range of [Equation 4] at the crank angle θbt_min at which the crankshaft 15 moves from bottom dead center to top dead center. Therefore, even if the rotational center line C of the crankshaft 15 does not coincide with the center of the cylinder chamber 31, the compressor 2 can reliably bring the piston 33 into contact with the cylinder 32 at least once during one rotation of the crankshaft 15, thereby forcing the piston 33 to rotate about its own axis, and prevents mechanical locking of the crankshaft 15 due to contact between the piston 33 and the cylinder 32.

[0082] Furthermore, the compressor 2 according to this embodiment has a minimum gap δ1 that is set within the range of [Equation 2] or the range of [Equation 4] when the crankshaft 15 and the main bearing 16 are pressed together and the eccentric portion 26 and the piston 33 are pressed together so as to maximize the gap δ1. Therefore, the relationship between the gaps δ1, δ2, and δ3 of the compressor 2 can be reliably and easily set when the compression mechanism 13 is stopped or during the process of assembling the compression mechanism 13.

[0083] Furthermore, the compressor 2 according to this embodiment has a gap δ1 between the piston 33 and the cylinder 32 that is set in the range of [Equation 1] at the crank angle θtb at which the crankshaft 15 moves from top dead center to bottom dead center, and that is set in the range of [Equation 3] at the crank angle θbt at which the crankshaft 15 moves from bottom dead center to top dead center. Therefore, the compressor 2 can reliably bring the piston 33 into contact with the cylinder 32 at least once during one rotation of the crankshaft 15, thereby forcing the piston 33 to rotate on its own axis, and prevents mechanical locking of the crankshaft 15 due to contact between the piston 33 and the cylinder 32.

[0084] Furthermore, the compressor 2 according to this embodiment has the gap δ1 set within the range of [Equation 1] and the range of [Equation 3] when the crankshaft 15 and the main bearing 16 are pressed together and the eccentric portion 26 and the piston 33 are pressed together so as to maximize the gap δ1. Therefore, the relationship between the gaps δ1, δ2, and δ3 of the compressor 2 can be reliably and easily set when the compression mechanism 13 is stopped or during the process of assembling the compression mechanism 13.

[0085] Furthermore, the compressor 2 according to this embodiment includes the piston 33 having a hardness greater than that of the cylinder 32. Therefore, even if the piston 33 comes into contact with or collides with the cylinder 32 more violently than expected, the compressor 2 can protect the piston 33 from wear or damage, and can ensure the integrity of the sliding portion between the vane 35 and the piston 33 during subsequent operation of the compressor 2.

[0086] Furthermore, the compressor 2 according to this embodiment includes the piston 33 having a Rockwell hardness of HRC 40 to HRC 55 and the cylinder 32 having a Rockwell hardness of HRB 80 to HRB 100. Therefore, the compressor 2 can more reliably protect the piston 33 from wear or damage and can ensure a sound sliding state between the piston 33 and the vane 35.

[0087] Furthermore, the compressor 2 according to this embodiment draws and compresses carbon dioxide into the cylinder chamber 31. That is, the compressor 2 can preferably avoid stopping the rotational motion of the piston 33 even when used to compress a refrigerant that needs to be compressed to a high pressure, such as carbon dioxide.

[0088] Furthermore, the compressor 2 according to this embodiment includes a sealed container 11 that seals in polyalkylene glycol oil. Therefore, even when the compressor 2 is used to compress a refrigerant that needs to be compressed to a high pressure, such as carbon dioxide, it is possible to prevent problems, such as seizure, that may occur due to the piston 33 coming into contact with the cylinder 32.

[0089] Therefore, according to the compressor 2 of this embodiment, it is possible to reliably prevent the rotational motion of the piston from stopping and to reduce the influence of mechanical loss.

[0090] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0091] 1... Refrigeration cycle device, 2... rotary compressor, 3... radiator, 5... expansion device, 6... heat absorber, 7... accumulator, 8... refrigerant piping, 8s... suction pipe, 8d... discharge pipe, 11... sealed container, 11a... body portion, 11b... end plate, 11c... end plate, 12... electric motor, 13... compression mechanism portion, 15... crankshaft, 15a... intermediate portion, 15b... lower end portion, 15o... circumferential surface of crankshaft, 16... main bearing, 16i... inner circumferential surface of main bearing, 17... secondary Bearing, 18...sealed terminal portion, 21...stator, 22...rotor, 23...lead wire, 25...rotor core, 26...eccentric portion, 26o...circumferential surface of eccentric portion, 31...cylinder chamber, 31c...compression chamber, 31s...suction chamber, 32...cylinder, 32i...inner surface of cylinder, 33...rolling piston, 33i...inner surface of piston, 33o...outer surface of piston, 35...vane, 38...fastening member, 37...discharge muffler, 39...refrigerant oil.

Claims

1. a cylinder that defines a cylinder chamber; a crankshaft having an eccentric portion disposed within the cylinder chamber; a piston fitted onto the eccentric portion and disposed in the cylinder chamber; a vane that comes into contact with the piston and divides the cylinder chamber into a suction chamber and a compression chamber, The piston contacts the cylinder at least once during one rotation of the crankshaft.

2. a bearing that is combined with the cylinder to close the cylinder chamber and that rotatably supports the crankshaft, At a crank angle at which the crankshaft moves from top dead center to bottom dead center, The minimum gap δ1 between the piston and the cylinder is The relationship between the gap δ2 between the piston and the eccentric portion and the gap δ3 between the crankshaft and the bearing is ((gap δ2 + gap δ3) ÷ 2 × 0.5) ≦ (minimum gap δ1) ≦ ((gap δ2 + gap δ3) ÷ 2) 2. The rotary compressor according to claim 1, wherein the first range is set to a range represented by

3. a bearing that is combined with the cylinder to close the cylinder chamber and that rotatably supports the crankshaft, At a crank angle at which the crankshaft moves from bottom dead center to top dead center, The minimum gap δ1 between the piston and the cylinder is The relationship between the gap δ2 between the piston and the eccentric portion and the gap δ3 between the crankshaft and the bearing is ((gap δ2 + gap δ3) ÷ 2 × 0.2) ≦ (minimum gap δ1) ≦ ((gap δ2 + gap δ3) ÷ 2 × 0.8) 2. The rotary compressor according to claim 1, wherein the first range is set to a range represented by

4. 4. The rotary compressor according to claim 2, wherein when the crankshaft and the bearing are pressed together and the eccentric portion and the piston are pressed together so that the gap δ1 is maximized, the minimum gap δ1 is set to be within the first range.

5. a bearing that is combined with the cylinder to close the cylinder chamber and that rotatably supports the crankshaft, At a crank angle at which the crankshaft moves from top dead center to bottom dead center, The gap δ1 between the piston and the cylinder is The relationship between the gap δ2 between the piston and the eccentric portion and the gap δ3 between the crankshaft and the bearing is ((gap δ2 + gap δ3) ÷ 2 × 0.5) ≦ (gap δ1) ≦ ((gap δ2 + gap δ3) ÷ 2) is set to the third range represented by At a crank angle at which the crankshaft moves from bottom dead center to top dead center, The gap δ1 is ((gap δ2 + gap δ3) ÷ 2 × 0.2) ≦ (gap δ1) ≦ ((gap δ2 + gap δ3) ÷ 2 × 0.8) The rotary compressor according to claim 1 , wherein the rotational speed is set to a fourth range represented by:

6. 6. The rotary compressor according to claim 5, wherein the gap δ1 is set to the third range and the fourth range when the crankshaft and the bearing are pressed together and the eccentric portion and the piston are pressed together so that the gap δ1 is maximized.

7. 4. The rotary compressor according to claim 1, wherein the hardness of the piston is greater than the hardness of the cylinder.

8. 8. The rotary compressor according to claim 7, wherein the piston has a Rockwell hardness of HRC 40 to HRC 55, and the cylinder has a Rockwell hardness of HRB 80 to HRB 100.

9. 4. The rotary compressor according to claim 1, wherein carbon dioxide is sucked into the cylinder chamber and compressed.

10. 4. The rotary compressor according to claim 1, further comprising a sealed container that houses the cylinder, the crankshaft, the piston, and the vane and that seals polyalkylene glycol oil therein.