JP4470914B2 - 2-stage compressor - Google Patents

Description

The present invention relates to a two-stage compressor suitable for application to a refrigeration cycle apparatus using CO ₂ as a refrigerant.

  As a technique related to a conventional two-stage compressor, for example, a technique disclosed in Patent Document 1 is known. In this two-stage compressor, the first compression part and the second compression part are accommodated in a sealed container, and the internal pressure type is such that the inside of the sealed container has an intermediate pressure. As the flow path through which the refrigerant gas flows, the first compression section leads from the first compression section to the second compression section and directly from the first compression section to the second compression section. And a second flow path connected thereto. Further, the volume ratio of the first compression section and the second compression section is set so that the intermediate pressure becomes equal to the equilibrium pressure (internal pressure that is in an equilibrium state when the compressor is stopped).

The refrigerant compressed in the first compression unit is once diffused into the sealed container by the first flow path, and the lubricating oil contained in the refrigerant is separated and stored at the bottom in the sealed container. This lubricating oil lubricates the external sliding portions of the first and second compressors. In addition, the difference between the intermediate pressure and the pressure in the first compression section enables supply of lubricating oil to the first compression section. Furthermore, here, by making the intermediate pressure the same as the equilibrium pressure, the pressure fluctuation in the sealed container at the time of start-up is reduced to suppress oil forming. That is, the lubricating oil in the form of foam is prevented from flowing out of the two-stage compressor itself through the second compression section and the lubricating oil in the sealed container being insufficient. In addition, the pressure resistance design of the sealed container is facilitated, and the weight can be reduced.
JP 2001-73976 A

  However, since the lubricating oil that accumulates in the bottom of the sealed container cannot be supplied to the inside of the second compression part due to the difference between the pressure in the second compression part and the intermediate pressure, for the second compression part, from the first compression part Relying on the lubricating oil contained in the refrigerant supplied by the second flow path. And in order to ensure this lubricating oil, it becomes difficult to reduce the oil rate of the refrigerant | coolant in a refrigerating-cycle apparatus. If the oil rate of the refrigeration cycle apparatus is high, the efficiency of the heat exchanger deteriorates, the pressure loss in the piping system increases, and the efficiency of the refrigeration cycle apparatus generally decreases.

  In view of the above problems, an object of the present invention is to provide a two-stage compressor that can reduce the oil rate of refrigerant and improve the efficiency of a refrigeration cycle apparatus.

  In order to achieve the above object, the present invention employs the following technical means.

In the first aspect of the present invention, the first compressor (120) that compresses the refrigerant in the refrigeration cycle, and the second compressor (130) that further compresses the refrigerant compressed by the first compressor (120). In the two-stage compressor that is housed in the container (110), the lubricating oil separator (180) that separates the lubricating oil contained in the refrigerant on the discharge side of the second compression section (130) is provided in the container (110). The first compression part (120) is supported by the support part (121) below the container (110), and the second compression part (130) is provided in the container (110). 1 provided on the upper side of the compression part (120), and the support part (121) can pass the lubricating oil separated by the lubricating oil separator (180) toward the bottom part in the container (110). lubricant bore (122) is characterized in that is provided comprising

  As a result, when the refrigerant is compressed and discharged from the two-stage compressor (100), the refrigerant can be made substantially free of lubricating oil, so the efficiency of the heat exchanger in the refrigeration cycle apparatus can be reduced and the piping system It is possible to improve the efficiency of the refrigeration cycle apparatus by preventing an increase in pressure loss.

  As the lubricating oil separator (180), a centrifugal separation type is suitable as in the invention described in claim 2, and can be easily handled with an inexpensive structure.

  In the invention according to claim 3, in the container (110), an intermediate pressure region (111, 111) that is an intermediate pressure between the suction pressure of the first compression unit (120) and the discharge pressure of the second compression unit (130). 114, 111a) and the separated lubricant is introduced into the intermediate pressure region (114, 111a).

  As a result, the intermediate pressure region (114, 111a) in the container (110) can be used as the separated oil reservoir (114, 111a), and the lubricating oil accumulated in the intermediate pressure region (114, 111a). Oil can be supplied to the suction side of the first compression part (120) by pressure difference, and the first compression part (120) and the second compression part (130) can be lubricated repeatedly. Further, by introducing the lubricating oil from the lubricating oil separator (180) to the intermediate pressure region (114, 111a), the pressure difference can be made smaller than when the lubricating oil is returned directly to the first compression section (120). It is not necessary to provide extremely small holes as the throttle portions (183, 117) for pressure reduction in the lubricant separator (180), and the processing can be facilitated.

  In the third aspect of the invention, as in the fourth aspect of the invention, the separated lubricating oil is brought into the suction side of the first compression section (120) by the pressure difference with the intermediate pressure region (114). If the supply flow path (150) to be supplied and the connection flow path (160) connecting the discharge side of the first compression section (120) and the suction side of the second compression section (130) are provided, separation The lubricating oil thus made can be reliably circulated through the first compression section (120) and the second compression section (130).

  In the invention according to claim 3, as in the invention according to claim 5, the separated lubricating oil is supplied to the suction side of the first compression section (120) by the pressure difference from the intermediate pressure region (114). And a suction channel (170) for sucking the separated lubricating oil into the second compression unit (130) by the negative pressure generated when the refrigerant is sucked into the second compression unit (130). According to this, the entire amount of refrigerant can once flow out from the first compression section (120) to the intermediate pressure region (111), and the intermediate pressure region (111) requires cooling. It is suitable for the case.

  In the third to fifth aspects of the invention, as in the sixth aspect of the invention, the motor part (190) that operates the first compression part (120) and the second compression part (130). And is suitable for application to an intermediate-pressure dome type electric two-stage compressor in which the motor unit (190) is accommodated in the intermediate pressure region (111).

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description mentioned later.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The two-stage compressor 100 is applied to a refrigeration cycle apparatus (not shown) that has two compression parts 120 and 130 in a housing 110 and operates using CO ₂ as a refrigerant. Is a compressor that compresses the pressure to a high pressure (pressure exceeding the critical pressure). More specifically, the two compression units 120 and 130 are operated by a motor unit 190, and the motor unit 190 is an intermediate pressure dome type electric motor housed in a housing 110 serving as an intermediate pressure between the two compression units 120 and 130. A two-stage compressor is used.

  Hereinafter, the details will be described with reference to FIG. 1. The housing 110 forms a cylindrical sealed container, and the first compression unit 120 and the second compression unit 130 are disposed therein. 120 and 130 are operated by a motor unit 190.

  The motor unit 190 is accommodated in a motor chamber 111 formed above the housing 110 and includes a rotor unit 191 and a stator unit 192. The rotor portion 191 is fixed to the shaft 193, and the stator portion 192 is fixed to the inner peripheral surface of the housing 110 by press-fitting on the outer peripheral side of the rotor portion 191. When electric power from an external power source (not shown) is supplied to the stator portion 192, the shaft 193 is driven to rotate as the rotor portion 191 rotates.

  The first compression unit 120 performs the first-stage compression, and is supported by the support unit 121 below the housing 110. The first compression unit 120 is a rotary compression unit in which a rotor and a vane (not shown) are arranged in a cylinder as is well known, and the rotor revolves by the shaft 193 of the motor unit 190. Do the compression work.

  A suction port 112 is connected to the suction side of the first compression unit 120 via a flow path (not shown) in the support part 121, and the refrigerant flows out from the evaporator (not shown) side of the refrigeration cycle apparatus. Is allowed to flow in. Further, the support portion 121 is provided with a lubricating oil hole 122 through which lubricating oil separated by a lubricating oil separator 180 described later can pass toward the bottom side in the housing 110. Note that an oil storage part 114 in which the lubricating oil is stored is formed between the bottom part in the housing 110 and the first compression part 120.

  The second compression unit 130 further compresses the refrigerant compressed by the first compression unit 120 (second-stage compression), and is provided in the housing 110 above the first compression unit 120. . The basic structure is a rotary compression unit similar to the first compression unit 120, and is supported in the housing 110 by the support unit 131. The rotor revolves around the shaft 193 of the motor unit 190 to perform compression work. Note that a lubricating oil hole 132 is provided in the support portion 131 of the second compression portion 130.

  The first compression section 120 is provided with a motor chamber discharge section 141 that opens from the discharge side to the motor chamber 111 through the lubricating oil hole 132, and the second compression section 130 includes a motor chamber discharge section from the motor chamber 111. The 2nd compression suction part 142 connected with the suction side of 2 compression parts 130 is provided. Therefore, the space between the motor chamber 111 in the housing 110, the first and second compression parts 120 and 130, and the oil storage part 114 are an intermediate pressure between the suction pressure of the first compression part 120 and the discharge pressure of the second compression part 130. The intermediate pressure region becomes.

  A discharge port 113 is provided on the discharge side of the second compression unit 130 and is connected to the condenser (not shown) side of the refrigeration cycle apparatus. Between the 2nd compression part 130 and the discharge outlet 113, the lubricating oil separator 180 used as the characteristic part of this invention is provided. The lubricating oil separator 180 is of a centrifugal type that separates the lubricating oil contained in the refrigerant on the discharge side of the second compression unit 130, and as shown in FIG. 2, a separation pipe 181, a separation cylinder 182, a throttle Part 183 and the like.

  The separation pipe 181 is a pipe member having a lid portion 181 a and is joined to the upper side of the bottomed cylindrical separation cylinder 182 so that the inside of the separation cylinder 182 communicates with the discharge port 113. At the bottom of the separation cylinder 182, there is provided a throttle part 183 that is formed by pores and reduces the internal pressure of the separation cylinder 182 to communicate with the oil storage part 114. Further, as shown in FIG. 3, the separation cylinder 182 is provided with an introduction passage 184 so as to contact the upper inner peripheral surface of the separation cylinder 182, and the discharge side of the second compression unit 130 and the inside of the separation cylinder 182 are connected. I try to communicate.

  A lubricating oil supply pipe (supply channel) 150 connected to the suction side of the first compression unit 120 is provided from the vicinity of the bottom of the housing 110. Furthermore, a connection pipe (connection flow path) 160 that directly connects the two compression sections 120 and 130 is provided between the discharge side of the first compression section 120 and the suction side of the second compression section 130.

  Next, operation and effects based on the above configuration will be described. In the two-stage compressor 100, the first compressor 120 and the second compressor 130 are operated by driving the motor unit 190, and the refrigerant sucked from the suction port 112 is first compressed by the first compressor 120. Done. Further, as will be described later, the lubricating oil stored in the oil storage unit 114 is first compressed through the lubricating oil supply pipe 150 due to the pressure difference between the intermediate pressure in the oil storage unit 114 and the suction pressure of the first compression unit 120. Supplied in the section 120 and lubricates the first compression section 120.

  Part of the refrigerant compressed by the first compression unit 120 is once diffused from the motor chamber discharge unit 141 into the motor chamber 111 to cool the motor unit 190, and from the second compression suction unit 142 to the second compression unit 130. Inhaled. When the refrigerant is diffused in the motor chamber 111, the lubricating oil contained in the refrigerant is separated and stored in the oil storage unit 114 through the lubricating oil holes 132 and 122. Moreover, the refrigerant | coolant which passes along the connection pipe 160 from the 1st compression part 120 flows in in the 2nd compression part 130, including lubricating oil, and lubricates in the 2nd compression part 130.

  As described above, the refrigerant flowing in from the second compression suction portion 142 and the connection pipe 160 is mixed, and the second compression portion 130 performs the second-stage compression. The compressed refrigerant further flows into the separation cylinder 182 from the discharge side of the second compression unit 130 via the introduction passage 184 of the lubricating oil separator 180. At this time, the refrigerant flows downward while rotating between the separation pipe 181 and the separation cylinder 182, and the refrigerant having a small specific gravity flows into the separation pipe 181 and flows out from the discharge port 113.

  On the other hand, the lubricating oil having a large specific gravity in the refrigerant is separated to the inner peripheral wall side of the separation cylinder 182 by centrifugal force and descends by gravity, and the pressure in the separation cylinder 182 (discharge pressure of the second compression unit 130) and the oil storage section Due to the difference from the pressure (intermediate pressure) in 114, the oil flows out from the throttle portion 183 through the lubricating oil hole 122 and is stored in the oil storage portion 114.

  Thus, in the present invention, by providing the lubricating oil separator 180 on the discharge side of the second compression unit 130, when the refrigerant is compressed and discharged from the two-stage compressor 100 to the condenser side of the refrigeration cycle apparatus, Therefore, it is possible to improve the efficiency of the refrigeration cycle apparatus by preventing a decrease in efficiency of the heat exchanger in the refrigeration cycle apparatus, an increase in pressure loss in the piping system, and the like. .

  As the lubricating oil separator 180, a centrifugal separator is used, which can be easily handled with an inexpensive structure.

  Further, the inside of the housing 110 serving as an intermediate pressure region can be used as a lubricating oil reservoir 114 separated by the lubricating oil separator 180, and the separated lubricating oil is first compressed from the lubricating oil supply pipe 150 by the pressure difference. The first compression unit 120 and the second compression unit 130 can be lubricated repeatedly by supplying the first compression unit 120 to the suction side of the unit 120 and further supplying the second compression unit 130 through the connection pipe 160.

  Furthermore, by introducing the lubricating oil from the lubricating oil separator 180 to the oil storage part 114, the pressure difference can be made smaller than when the lubricating oil is returned directly to the first compression part 120. Therefore, it is not necessary to provide a very small hole as the narrowed portion 183, and the processing can be facilitated.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG. In the second embodiment, the connection pipe 160 is eliminated from the first embodiment, and a suction pipe 170 is provided instead.

  The suction pipe 170 constitutes the suction flow path of the present invention, and is a flow path that is connected to the side wall of the second compression suction part 142 from the bottom part (oil storage part 114) in the housing 110.

  In the second embodiment, the entire amount of the refrigerant compressed by the first compression unit 120 flows out from the motor chamber discharge unit 141 and diffuses into the motor chamber 111 once. At this time, the lubricating oil in the refrigerant is separated by this diffusion, and is stored in the oil storage section 114 through the lubricating oil holes 132 and 122. The refrigerant is sucked into the second compression unit 130 from the second compression suction unit 142.

  Then, due to the negative pressure generated when the refrigerant is sucked into the second compression suction portion 142, the lubricating oil stored in the oil storage portion 114 is sucked into the second compression portion 130 through the suction pipe 170, and the second compression portion. Perform lubrication within 130.

  Thus, the cooling effect on the motor unit 190 can be enhanced by allowing the entire amount of the refrigerant from the first compression unit 120 to flow out into the motor chamber 111. Note that the second compression unit 130 can be supplied with lubricating oil by the suction pipe 170, and the lubrication of the second compression unit 130 can be satisfied.

( Reference example )
A reference example of the present invention is shown in FIG. In this reference example , the two-stage compressor 100 is applied to a reciprocating two-stage compressor in which the crank chamber 111a has an intermediate pressure system.

  The two-stage compressor 100 forms compression parts 120 and 130 in which a piston 124 is reciprocated by a crank mechanism (mechanism) 123 in which a swash plate 123b is fixed to a shaft 123a. The piston 124 is a cylindrical member having a recess 124c formed in the center and connected to the swash plate 123b via a shoe 125. A large-diameter portion (compression member) 124a and a small-diameter portion (compression member) 124b are formed on both end sides in the longitudinal direction of the piston 124, and are inserted into cylinders 115a and 115b provided in the housing 110. The first compression unit 120 is configured on the diameter portion 124a side, and the second compression unit 130 is configured on the small diameter portion 124b side. The swash plate 123b of the crank mechanism 123 and the vicinity of the recess 124c of the piston 124 are accommodated in a space formed between the first compression unit 120 and the second compression unit 130, that is, the crank chamber 111a.

  The crank chamber 111a communicates with the first-stage discharge chamber 126 of the first compression section 120 by the first discharge flow path 127, and the second-stage suction chamber of the second compression section 130 by the suction flow path 133. 134. Therefore, the crank chamber 111 a corresponds to an intermediate pressure region that is an intermediate pressure between the suction pressure of the first compression unit 120 and the discharge pressure of the second compression unit 130.

  A lubricating oil separator 180 similar to that in the first embodiment is provided on the discharge side of the second compression unit 130, that is, on the downstream side of the second-stage discharge chamber 135. An oil storage chamber 114 a is provided below the lubricating oil separator 180 and communicates with the inside of the separation cylinder 182. Further, the inside of the oil storage chamber 114a is communicated with the inside of the crank chamber 111a by a lubricating oil return passage 116 having a throttle portion 117.

  In the two-stage compressor 100 configured as described above, the refrigerant sucked from the suction port 112 is compressed in the first stage by the first compression unit 120, and the first discharge flow from the first-stage discharge chamber 126. It passes through the passage 127 and flows into the crank chamber 111a. Then, the refrigerant flows from the suction flow path 133 through the second-stage suction chamber 134 into the second compression unit 130, and the second-stage compression is performed. At this time, lubrication between the small diameter portion 124b of the piston 124 and the cylinder 115b is accomplished by the lubricating oil in the refrigerant. Thereafter, the refrigerant flows into the lubricating oil separator 180, and the lubricating oil in the refrigerant is separated and stored in the oil storage chamber 114a from the separation cylinder 182. The refrigerant is discharged from the discharge port 113 to the condenser side of the refrigeration cycle apparatus.

  The lubricating oil stored in the oil storage chamber 114a is caused by the difference in pressure between the pressure in the oil storage chamber 114a (second-stage discharge pressure) and the pressure in the crank chamber 111a (intermediate pressure), and the lubricating oil return passage 116 and the throttle portion. 117 is introduced into the crank chamber 111a. The lubricating oil lubricates the crank mechanism 123 (such as the rotation support portion of the shaft 123a and the connection portion of the swash plate 123b with the piston 124). Further, due to the pressure difference between the crank chamber 111a and the suction side of the first compression portion 120, the lubricating oil is also supplied between the large diameter portion 124a of the piston 124 and the cylinder 115a, and lubrication at that portion is achieved.

  As a result, the first and second compression parts 120 and 130 and the crank mechanism 123 can be lubricated, and the refrigerant discharged by the lubricating oil separator 180 can be made substantially free of lubricating oil. The efficiency of the cycle apparatus can be improved.

(Other embodiments)
In the first and second embodiments, the lubricating oil separated by the lubricating oil separator 180 is introduced into the oil storage unit 114 as an intermediate pressure region. However, the present invention is not limited to this, and the suction of the first compression unit 120 is performed. Alternatively, a flow path connected to the side may be provided and guided directly to the first compression unit 120.

It is sectional drawing which shows the two-stage compressor in 1st Embodiment of this invention. It is sectional drawing which shows the lubricating oil separator in FIG. It is sectional drawing which shows the AA part in FIG. It is sectional drawing which shows the two-stage compressor in 2nd Embodiment of this invention. It is sectional drawing which shows the two-stage compressor in the reference example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Two-stage compressor, 110 ... Housing (container), 114 ... Oil storage part (intermediate pressure area), 120 ... First compression part, 123 ... Crank mechanism (mechanism), 124a ... large diameter part (compression member), 124b ... small diameter part (compression member), 130 ... second compression part, 150 ... lubricating oil supply pipe (supply flow path), 160 ... connection Pipe (connection channel), 170... Suction pipe (suction channel), 180... Lubricating oil separator, 190.

Claims (6)

A first compression section (120) for compressing the refrigerant in the refrigeration cycle;
In the two-stage compressor comprising a container (110) and a second compression unit (130) that further compresses the refrigerant compressed by the first compression unit (120).
A lubricating oil separator (180) for separating lubricating oil contained in the refrigerant is provided in the container (110) on the discharge side of the second compression unit (130) ,
The first compression part (120) is supported by a support part (121) below the container (110), and the second compression part (130) is the first compression part in the container (110). Part (120) is provided on the upper side,
The support portion (121) is provided with a lubricating oil hole (122) through which the lubricating oil separated by the lubricating oil separator (180) can pass toward the bottom side in the container (110). two-stage compressor, characterized in that there.   The two-stage compressor according to claim 1, wherein the lubricating oil separator (180) is a centrifugal type. In the container (110), intermediate pressure regions (111, 114, 111a) that form an intermediate pressure between the suction pressure of the first compression unit (120) and the discharge pressure of the second compression unit (130) are formed. And
The two-stage compressor according to any one of claims 1 and 2, wherein the separated lubricating oil is introduced into the intermediate pressure region (114, 111a). A supply flow path (150) for supplying the separated lubricating oil to the suction side of the first compression section (120) by a pressure difference from the intermediate pressure region (114);
The connection flow path (160) which connects the discharge side of the said 1st compression part (120) and the suction side of the said 2nd compression part (130) is provided, The 2 of Claim 3 characterized by the above-mentioned. Stage compressor. A supply flow path (150) for supplying the separated lubricating oil to the suction side of the first compression section (120) by a pressure difference from the intermediate pressure region (114);
A suction flow path (170) for sucking the separated lubricating oil into the second compression section (130) by a negative pressure generated when the refrigerant is sucked into the second compression section (130) is provided. The two-stage compressor according to claim 3. A motor unit (190) for operating the first compression unit (120) and the second compression unit (130);
The two-stage compressor according to any one of claims 3 to 5, wherein the motor unit (190) is accommodated in the intermediate pressure region (111).

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