ES2953629T3 - rotary compressor - Google Patents

Abstract

A rotary compressor is provided including first and second cylinders arranged in the axial direction of a drive shaft, and in which a suction path is formed for supplying a refrigerant, supplied through a suction pipe from an external apparatus, to each of the compression chambers. The surface area of a region facing the suction path on the second cylinder is less than the surface area of a region facing the suction path on the first cylinder. The difference between the height of the second cylinder in the axial direction and the height in the axial direction of a piston arranged in a compression chamber of the second cylinder is less than the difference between the height of the first cylinder in the axial direction and the height in the axial direction of a piston arranged in a compression chamber of the first cylinder (A3-A4 < A1-A2). Therefore, both compressor miniaturization and inhibition of compressor efficiency degradation can be achieved. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

rotary compressor

[Technical field]

The present invention relates to a rotary compressor used for an air conditioner, for example.

[Background of the art]

Japanese Patent Pending Publication No. 2016-118142 describes a 2-cylinder rotary compressor that includes an upper cylinder and a lower cylinder and is configured to compress refrigerant in a compression chamber formed in each of the cylinders. An accumulator is connected next to the compressor. The accumulator is connected to two suction pipes. One of the two suction pipes is connected to the upper cylinder, while the other of the suction pipes is connected to the lower cylinder. The upper cylinder and the lower cylinder are supplied with refrigerant from the accumulator through the respective suction pipes. In the compression chamber formed in each of the upper and lower cylinders, a piston having a roller is provided. The compression chamber is divided by the piston into a low pressure chamber into which the coolant is introduced and a high pressure chamber into which the coolant is compressed.

[List of quotes]

[Patent bibliography]

[Patent Bibliography 1] Japanese Patent Pending Publication No. 2016-118142

Document WO 03/054391 describes a compressor having the characteristics of the preamble of independent claim 1.

JP H02218884 describes a different rotary compressor and measures to react to thermal loads.

[Compendium of invention]

[Technical problem]

When downsizing a 2-cylinder rotary compressor, an external device such as an accumulator for refrigerant supply is preferably also downsized. However, it is difficult to reduce the size of the accumulator when two suction pipes are connected to the accumulator. To solve this problem, the accumulator can be reduced by connecting the 2-cylinder rotary compressor to the accumulator through a single suction pipe. This arrangement, however, has the disadvantage that the suction resistance may increase due to branching of the suction pipe and therefore the efficiency of the compressor may deteriorate.

An object of the present invention is to provide a rotary compressor that can be reduced in size and is capable of suppressing the deterioration of compressor efficiency.

[Solution to the problem]

A rotary compressor of the present invention is a rotary compressor comprising a compression mechanism and a drive mechanism including a drive shaft that drives the compression mechanism, the compression mechanism and a drive mechanism being housed in the rotary compressor. . The compression mechanism includes: a plurality of cylinders in which compression chambers are formed, respectively, the cylinders being aligned in the axial direction of the transmission shaft, so that the transmission shaft is within the compression chambers; a plurality of end plates provided at both ends of the cylinders in the axial direction to define the compression chambers; and a plurality of pistons provided in the respective compression chambers and driven by the drive shaft. The cylinders include a first cylinder and a second cylinder adjacent to the first cylinder through one of the end plates. A suction passage including a first passage and a second passage branching from the first passage is formed in the rotary compressor, the first passage supplies refrigerant to the compression chamber of the first cylinder from an external device through a suction pipe, and the second step supplies the coolant to the compression chamber of the second cylinder. The surface area of a region facing the suction passage in the second cylinder is less than the surface area of a region facing the suction passage in the first cylinder. A difference between the height of the second cylinder in the axial direction and the height in the axial direction of the piston provided in the compression chamber of the second cylinder is less than the difference between the height of the first cylinder in the axial direction and the height in the axial direction of the piston arranged in the compression chamber of the first cylinder.

The external device may be an accumulator or a device that is provided between an accumulator and the rotary compressor of the present invention.

In the present invention, the first passage may be arranged so that the first passage passes through the first cylinder, but does not pass through the second cylinder, and the second passage branches from the first passage may be the first cylinder and may pass either by the first cylinder and the second cylinder.

In the present invention, the first cylinder may be configured to be inserted through the suction pipe so that a leading end of the suction pipe is in the first cylinder.

In the present invention, an end plate disposed on the opposite side of the second cylinder with respect to the first cylinder may be configured to be inserted by the suction pipe, so that a front end of the suction pipe is on the end plate. .

In the present invention preferably, in each of the cylinders, a difference between the height of the cylinder in the axial direction and the height in the axial direction of the piston provided in the compression chamber of the cylinder decreases as the surface area of a region facing the suction passage in the cylinder.

In the present invention, preferably, in each of the cylinders, a relationship 3.9x0.0001 ≤ (Hc-Hp)/Hc-1.4x0.0001 xAs/(HcLs)≤6.7x0.0001 is met where the height of the cylinder in the axial direction is denoted as Hc (mm), the height in the axial direction of the piston provided in the compression chamber in the cylinder is denoted as Hp (mm), the surface area of a region facing the passage of suction in the cylinder is denoted as As (mm2) and the length of the suction passage in the cylinder in a direction orthogonal to the axial direction is denoted as Ls (mm).

[Advantageous effects of the invention]

A suction passage is formed in the rotary compressor of the present invention, and the suction passage includes a first passage through which refrigerant is supplied to the compression chamber of the first cylinder and a second passage which is branched, from the first passage, and through which the coolant is supplied to the compression chamber of the second cylinder. The surface area of a region facing the suction passage in the second cylinder is less than the surface area of a region facing the suction passage in the first cylinder. For this reason, compared with the first cylinder, the decrease in coolant temperature around the region facing the suction passage in the cylinder is small in the second cylinder. For this reason, the temperature difference between the second cylinder and the piston provided in the compression chamber of the second cylinder is small, with the result that the difference in the amount of dimensional change between the second cylinder and the piston on expansion thermal is small. In this rotary compressor, the difference between the cylinder height and the piston height (i.e., the gap between the end face of the piston in the axial direction and the end face of the end plate in the axial direction) is arranged to be small in the second cylinder compared to the first cylinder, with the result that oil leakage from the inner periphery of the piston to the compression chamber is suppressed, and thus the volume efficiency and indicated efficiency are improved for the second cylinder. Therefore, even when the two cylinders are connected to the external device by a single suction pipe to reduce the size of the compressor, the decrease in compressor efficiency due to the increase in suction resistance is compensated by the improvement in efficiency. of the indicated volume and efficiency, with the result that the decrease in compressor efficiency is suppressed. To put it another way, both the reduction of compressor size and the suppression of the decrease in compressor efficiency are achieved.

[Brief description of the drawings]

[FIG. 1] Figure 1 is a view showing a rotary compressor of the first embodiment of the present invention, together with an accumulator.

[FIG. 2A] Figure 2A is a top view of an upper cylinder of the rotary compressor shown in Figure 1.

[FIG. 2B] Figure 2B is a top view of a lower cylinder of the rotary compressor shown in Figure 1.

[FIG. 3] Figure 3 is a partially enlarged view of a compression mechanism of the rotary compressor shown in Figure 1.

[FIG. 4] Figure 4 is a view showing a rotary compressor of the second embodiment of the present invention.

[FIG. 5A] Figure 5A is a top view of an upper cylinder of the rotary compressor shown in Figure 4.

[FIG. 5B] Figure 5B is a top view of a lower cylinder of the rotary compressor shown in Figure 4.

[FIG. 6] Figure 6 is a partially enlarged view of a compression mechanism of the rotary compressor shown in Figure 4.

[FIG. 7] Figure 7 is a view showing a rotary compressor of the third embodiment of the present invention.

[FIG. 8] Figure 8 is a partially enlarged view of a compression mechanism of the rotary compressor shown in Figure 7.

[FIG. 9] Figure 9 is a graph showing the results of a test performed using various rotary compressors.

[Description of the achievements]

[First realization]

To begin with, a rotary compressor 1 of the first embodiment will be described with reference to Figure 1 to Figure 3. As shown in Figure 1, the compressor 1 of the present embodiment is a 2-cylinder rotary compressor that includes a container closed container 2 and further includes a drive mechanism 3 and a compression mechanism 4 that are housed in the closed container 2. The closed container 2 is a cylindrical container that is closed at both the upper and lower ends. An accumulator 5 is attached to the closed container 2. The accumulator 5 is connected to the compression mechanism 4 by a single suction pipe 6 through which the refrigerant is introduced. An outlet pipe 7 is provided at the top of the closed container 2 to discharge the refrigerant compressed by the compression mechanism 4. The lubricating oil is stored at the bottom of the closed container 2.

The compressor 1 is incorporated, for example, in a refrigeration cycle in an air conditioner, and is configured to compress the refrigerant supplied from the suction pipe 6 and discharge the refrigerant from the outlet pipe 7. The refrigerant used in the Compressor 1 is, for example, R32 or R410A. The compressor 1 is oriented as shown in Figure 1, that is, it is oriented such that the axial direction (which is identical to the axial direction of a transmission shaft 3b described later) of the compressor 1 is parallel to the direction from top to bottom.

The driving mechanism 3 is provided to drive the compression mechanism 4 and is constituted by a motor 3a which is a driving source and the transmission shaft 3b attached to the motor 3a. The motor 3a includes a substantially annular stator 3aa fixed to the inner circumferential surface of the closed container 2 and a substantially annular rotor 3ab provided radially within the stator 3aa with an air gap formed between the stator and the rotor. The rotor 3ab includes a magnet (not shown), while the stator 3aa includes a coil (not shown).

The drive shaft 3b is fixed to the inner circumferential surface of the rotor 3ab and rotates on its axis together with the rotor 3ab to drive the compression mechanism 4. The drive shaft 3b has eccentric portions 3c and 3d that are located in a chamber compression chamber 31 described below and in a compression chamber 51 described below, respectively (see Figure 2A, Figure 2B and Figure 3). Each of the eccentric portions 3c and 3d is cylindrical in shape and has a central axis that is eccentric from the center of rotation of the transmission shaft 3b. To the eccentric portions 3c and 3d, the pistons 32 and 52 of the compression mechanism 4 are attached, respectively.

Within a substantially lower half of the drive shaft 3b, an oil supply passage (not shown) is formed. The oil supply passage extends along the top-down direction and is branched into several parts in radial directions of the drive shaft 3b. A helical vane-shaped pump member (not shown) is attached to the lower end of the drive shaft 3b to suck the lubricating oil into the oil supply passage in accordance with the rotation of the drive shaft 3b. The lubricating oil sucked from the lower end of the transmission shaft 3b by the pump element is discharged from a side face of the transmission shaft 3b and is supplied to the sliding elements of the compression mechanism 4, such as the compression chambers 31 and 51 , For example.

The compression mechanism 4 includes upper mufflers 10a and 10b, an upper head 20 (end plate), an upper cylinder 30 (cylinder), a center plate 40 (end plate), a lower cylinder 50 (cylinder), a head lower 60 (end plate) and a lower muffler 70. These members are provided in this order from top to bottom, along the axial direction of the drive shaft 3b.

As shown in Figure 1 and Figure 2A, the upper cylinder 30 is a substantially circular plate. In a central portion of the upper cylinder 30, the compression chamber 31 is formed as a circular hole that penetrates the upper cylinder 30 in the axial direction of the transmission shaft 3b. The piston 32 is provided in the compression chamber 31. The piston 32 is constituted by an annular roller 32a and a vane 32b extending radially outward from the outer circumferential surface of the roller 32a. The roller 32a is rotatably attached with respect to the outer circumferential surface of the eccentric portion 3c and is provided in the compression chamber 31.

As shown in Figure 2A and Figure 3, in the upper cylinder 30, a side passage 30a extending in the radial direction of the upper cylinder 30 is formed as a suction passage for introducing coolant into the compression chamber 31 A radially inner end portion of the side passage 30a is open at the compression chamber 31, while a radially outer end portion of the side passage 30a is open at the outer circumferential surface of the upper cylinder 30. The suction pipe 6 is inserted into the side passage 30a from the radially outer end portion of the side passage 30a, and a front end of the suction pipe 6 is around the center of the side passage 30a. In the upper cylinder 30, a vertical passage 30b extending vertically downward from the side passage 30a is formed as a suction passage for introducing refrigerant into the compression chamber 51. The vertical passage 30b branches from a part of the side passage 30a, which is between the radially inner end portion of the side passage 30a and the forward end of the suction pipe 6. The vertical passage 30b extends vertically downward and is open on the lower surface of the upper cylinder 30.

As shown in Figure 2A, a vane housing portion 33 is formed in the upper cylinder 30. This portion 33 is a recess formed radially outward from the surface of the circumferential wall of the compression chamber 31. A pair of Bushings 34 are housed in the housing portion of the vane 33 to oppose each other in the circumferential direction of the upper cylinder 30. Each bushing 34 is one half of a substantially cylindrical member. The pair of bushings 34 can rotate in the housing portion of the vane 33 while the vane 32b is provided between them. Between the pair of bushings 34, the vane 32b can be moved in the radial direction of the upper cylinder 30. The compression chamber 31 is divided into a low pressure chamber and a high pressure chamber by the vane 32b.

As shown in Figure 1, the upper head 20 is provided to be in contact with the upper end face of the upper cylinder 30. The compression chamber 31 is defined by closing the upper end of the compression chamber 31 by the upper head 20. The upper head 20 has a substantially annular shape, and the drive shaft 3b is rotatably inserted into a central portion of the upper head 20. The upper head 20 is fixed to the inner circumferential surface of the closed container 2 by welding, for example.

The upper silencers 10a and 10b are located above the upper header 20. Between the upper header 20 and the upper silencer 10b and between the upper silencer 10a and the upper silencer 10b, an upper silencer space is formed. This muffler headspace is provided in order to reduce noise due to coolant discharge.

As shown in Figure 2A, a discharge hole 35 is formed in the upper head 20 to make the compression chamber 31 communicate with the space of the upper muffler so that the coolant compressed in the compression chamber 31 is discharged to the upper muffler space. The discharge port 35 is closed by a plate-shaped discharge valve (not shown). The discharge valve is elastically deformed when the pressure in the compression chamber 31 becomes equal to or greater than a predetermined pressure, with the result that the discharge port 35 opens.

The center plate 40 is a circular plate and is provided to be in contact with the lower end face of the upper cylinder 30 and the upper end face of the lower cylinder 50 as shown in Figure 1. As shown in Figure 3 , the central plate 40 closes the lower end of the compression chamber 31 of the upper cylinder 30 to define the compression chamber 31 and closes the upper end of the compression chamber 51 of the lower cylinder 50 to define the compression chamber 51. In the central plate 40, a vertical passage 40a connected to the vertical passage 30b of the upper cylinder 30 is formed as a suction passage for introducing the refrigerant into the compression chamber 51. The vertical passage 40a connects the vertical passage 30b of the upper cylinder 30 to a lateral passage 50a described later of the lower cylinder 50.

As shown in Figure 1 and Figure 2B, the lower cylinder 50 that is adjacent to the upper cylinder 30 through the central plate 40 is a substantially circular plate in the same way as the upper cylinder 30. In a central portion of the lower cylinder 50, the compression chamber 51 is formed as a circular hole that penetrates the lower cylinder 50 in the axial direction of the transmission shaft 3b. The piston 52 is provided in the compression chamber 51. The piston 52 is constituted by an annular roller 52a and a vane 52b extending radially outward from the outer circumferential surface of the roller 52a. The roller 52a is rotatably attached with respect to the outer circumferential surface of the eccentric portion 3d and is provided in the compression chamber 51.

As shown in FIG. 2B and in FIG. 3, in the lower cylinder 50, a side passage 50a extending in the radial direction of the lower cylinder 50 is formed as a suction passage for introducing the refrigerant into the compression chamber 51. The side passage 50a is a cut formed in the upper surface of the lower cylinder 50. A radially inner end portion of the side passage 50a is open in the compression chamber 51. A radially outer end portion of the side passage 50a is closed by the wall surface of the lower cylinder 50 in the radial direction and is open upwards. As shown in Figure 3, the radially outer end portion of the side passage 50a is connected to the vertical passage 40a of the center plate 40 at the upward opening. Except at the opening, the side passage 50a is closed by the bottom surface of the central plate 40.

As shown in FIG. 2B, a vane housing portion 53 is formed in the lower cylinder 50. This portion 53 is a recess formed radially outward from the surface of the circumferential wall of the compression chamber 51. A pair of bushings 54 are housed in the vane housing portion 53 to oppose each other in the circumferential direction of the lower cylinder 50. Each bushing 54 is one half of a substantially cylindrical member. The pair of bushings 54 can rotate in the housing portion of the vane 53 while the vane 52b is provided between them. Between the pair of bushings 54, the vane 52b can be moved in the radial direction of the lower cylinder 50. The compression chamber 51 is divided into a low pressure chamber and a high pressure chamber by the vane 52b.

As shown in Figure 1, the lower head 60 is provided to be in contact with the lower end face of the lower cylinder 50. The compression chamber 51 is defined by the lower end closure of the compression chamber 51 by the lower head 60. The lower head 60 has a substantially annular shape, and the drive shaft 3b is rotatably inserted into a central portion of the lower head 60.

The lower muffler 70 is provided below the lower header 60. A lower muffler space is formed between the lower header 60 and the lower muffler 70. This lower muffler space is provided in order to reduce noise due to the discharge of coolant. .

As shown in FIG. 2B, a discharge port 55 is formed in the lower header 60 to cause the compression chamber 51 to communicate with the lower muffler space so that the coolant compressed in the compression chamber 51 is discharged into the lower muffler space. The discharge port 55 is closed by a plate-shaped discharge valve (not shown). The discharge valve is elastically deformed when the pressure in the compression chamber 51 becomes equal to or greater than a predetermined pressure, with the result that the discharge port 55 opens.

The lower muffler space communicates with the upper muffler space through the through holes formed in the lower head 60, the lower cylinder 50, the center plate 40, the upper cylinder 30 and the upper head 20.

A suction passage including an upper suction passage (first passage) and a lower suction passage (second passage) branched from the upper suction passage (first passage) is formed in the rotary compressor 1 of the present embodiment. The upper suction passage feeds the compression chamber 31 of the upper cylinder 30 with coolant. The upper suction passage supplies the refrigerant to the compression chamber 51 of the lower cylinder 50. In the present embodiment, the upper suction passage is a part of the side passage 30a formed in the upper cylinder 30 and is a horizontal passage from the end front of the suction pipe 6 to the compression chamber 31. The upper suction passage passes through the upper cylinder 30, but does not pass through the lower cylinder 50. The lower suction passage is constituted by the vertical passage 30b formed in the upper cylinder 30, the vertical passage 40a formed in the central plate 40 and the lateral passage 50a formed in the lower cylinder 50 (see Figure 3). The lower suction passage passes through the upper cylinder 30 and the lower cylinder 50.

To put it another way, in the upper cylinder 30, a horizontal passage from the front end of the suction pipe 6 to the compression chamber 31 in the side passage 30a (not including a part from the front end of the suction pipe 6 to the radially outer end portion of the side passage 30a of the side passage the passage 30a) and the vertical passage 30b constitute the suction passage. The side passage 50a constitutes the suction passage in the lower cylinder 50. In the present embodiment, the surface area of a region facing the suction passage in the lower cylinder 50 is smaller than the surface area of a region facing towards the suction passage in the upper cylinder 30.

The expression "the surface area of a region facing a suction passage in a cylinder" indicates the surface area of the inner circumferential surface of a cylinder wall, which constitutes the suction passage, that is, the surface area of a cylinder wall surface, through which the refrigerant drawn from the accumulator 5 passes. For this reason, the surface area of the region facing the suction passage in the upper cylinder 30 is equal to the total surface area of the region facing towards the horizontal passage from the front end of the suction pipe 6 to the compression chamber 31 in the side passage 30a and the surface area of the region facing the vertical passage 30b, and the surface area of the region facing The suction passage in the lower cylinder 50 is equal to the surface area of the region facing the side passage 50a.

In the lower cylinder 50 in which the surface area of the region facing the suction passage is small compared to the upper cylinder 30, the decrease in temperature of the coolant around the region facing the suction passage is small compared to the upper cylinder 30. For this reason, a temperature difference between the lower cylinder 50 and the piston 52 provided in the compression chamber 51 of the lower cylinder 50 is small, with the result that the difference in the amount of dimensional change between the lower cylinder 50 and the piston 52 in thermal expansion is small.

Therefore, in the compressor 1 of the present embodiment, as shown in Figure 3, the difference between the height A3 of the lower cylinder 50 and the height A4 of the piston 52 in the compression chamber 51 of the lower cylinder 50 is less than the difference between the height A1 of the upper cylinder 30 and the height A2 of the piston 32 in the compression chamber 31 of the upper cylinder 30 (A3-A4≤A1-A2), The difference between the height A1 of the upper cylinder 30 and the height A2 of piston 32 and the difference between the height A3 of the lower cylinder 50 and the height A4 of piston 52 are those when the compressor 1 is not activated (that is, at a normal temperature).

In the rotary compressor 1 of the present embodiment, a suction passage is formed including an upper suction passage and a lower suction passage branched from the upper suction passage. The upper suction passage supplies coolant to the compression chamber 31 of the upper cylinder 30. The suction pipe (6) is connected to the compression mechanism (31). The lower suction passage supplies the refrigerant to the compression chamber 51 of the lower cylinder 50. The surface area of a region facing the suction passage in the lower cylinder 50 is smaller than the surface area of a region facing the suction passage in the upper cylinder 30. For this reason, compared with the upper cylinder 30, the decrease in the temperature of the coolant around the region facing the passage of suction in the cylinder is small in the lower cylinder 50. For this reason, a temperature difference between the lower cylinder 50 and the piston 52 provided in the compression chamber 51 of the lower cylinder 50 is small, with the result that the difference in the amount of dimensional change between the lower cylinder 50 and the piston 52 in thermal expansion is small. As a result, compared to the upper cylinder 30, problems are less likely to occur in the lower cylinder 50 even when the gaps between the end face in the axial direction of the piston 52 and the end faces in the axial direction of the plates ends 40 and 60 adjacent to piston 52 are narrow. This suppresses oil leakage from the inner periphery of the piston into the compression chamber and improves volume efficiency and indicated efficiency. Therefore, even when the two cylinders 30 and 50 are connected to the accumulator 5 by a single suction pipe 6 to reduce the size of the compressor 1, the decrease in the efficiency of the compressor due to the increase in suction resistance is compensated by the improvement in volume efficiency and indicated efficiency, with the result that the decrease in compressor efficiency is suppressed. As such, the reduction of the size of the compressor 1 and the suppression of the decrease in efficiency of the compressor are achieved in the present embodiment.

In the present embodiment, the upper suction passage (first passage) passes through the upper cylinder 30, but does not pass through the lower cylinder 50, while the lower suction passage (second passage) branches from the upper suction passage in the upper cylinder 30 and passes through both the upper cylinder 30 and the lower cylinder 50. With this arrangement, it is possible to easily construct the structure in which the surface area of the region facing the suction passage in the lower cylinder 50 is less than the surface area of the region facing the suction passage in the upper cylinder 30.

In addition to the above, in the present embodiment, the upper cylinder 30 is configured to be inserted by the suction pipe 6, so that the front end of the suction pipe 6 is provided inside the upper cylinder 30. With this arrangement, the The passage of the refrigerant from the front end of the suction pipe 6 to the compression chamber 31 of the upper cylinder 30 is constituted only by the linear side passage 30a, with the result that the increase in suction resistance is suppressed.

[Second realization]

Next, a compressor of the second embodiment will be described with reference to Figure 4 to Figure 6. While the compressor 1 of the first embodiment is arranged so that the upper cylinder 30 is configured to be inserted through the suction pipe 6 of the accumulator 5, the compressor 101 of the present embodiment differs from the compressor of the first embodiment in that an upper head 120 is configured to be inserted through a suction pipe 6 of an accumulator 5. In the present embodiment, the structures identical to those of the first embodiment are indicated with the same reference symbols and may not be explained.

In the compressor 101 of the present embodiment, a driving mechanism 3 and a compression mechanism 104 are housed. In this compressor 101, as shown in Figure 5A and Figure 6, a side passage 120a extending in the direction radial of the upper head 120 and a vertical passage 120b extending vertically downward from the side passage 120a are formed in the upper head 120 opposing a lower cylinder 50 on an upper cylinder 130, as a suction passage for introducing coolant into a compression chamber 31 of the upper cylinder 130. A radially inner end portion of the side passage 120a is closed by the wall surface of the upper head 120 in the radial direction and is open downward. The radially inner end portion of the side passage 120a is connected to a side passage 130a of the upper cylinder 130 at the downward opening. A radially outer end portion of the side passage 120a is open on the outer circumferential surface of the upper head 120. The suction pipe 6 is inserted into the side passage 120a, and a front end of the suction pipe 6 is around the center of the side step 120a.

In the upper cylinder 130, the side passage 130a extending in the radial direction of the upper cylinder 130 is formed as a suction passage for introducing the refrigerant into the compression chamber 31 of the upper cylinder 130. The side passage 130a is a cut formed on the upper surface of the upper cylinder 130. A radially inner end portion of the side passage 130a is open in the compression chamber 31. A radially outer end portion of the side passage 130a is closed by the wall surface of the upper cylinder 130 in the radial direction and is open upwards. The radially outer end portion of the side passage 130a is connected to the vertical passage 120b of the upper head 120 at the upward opening. Except at the opening, the side passage 130a is closed by the lower surface of the upper head 120. In the upper cylinder 130, a vertical passage 130b extending vertically downward from the side passage 130a is formed as a suction passage for introducing the refrigerant in the compression chamber 51 of a lower cylinder 150. The vertical passage 130b branches from the lateral passage 130a, extends vertically downward and is open on the lower surface of the upper cylinder 130.

In the center plate 40, a vertical passage 40a connected to the vertical passage 130b of the upper cylinder 130 is formed as a suction passage for introducing the refrigerant into the compression chamber 51 of the lower cylinder 50. The vertical passage 40a connects the vertical passage 130b from the upper cylinder 130 to a lateral passage 50a described later from the lower cylinder 50.

As shown in Figure 5B and Figure 6, in the lower cylinder 50 adjacent to the upper cylinder 130 through the central plate 40, a side passage 50a extending in the radial direction of the lower cylinder 50 is formed as a suction passage for introducing refrigerant into the compression chamber 51. The side passage 50a is a cut formed in the upper surface of the lower cylinder 50. A radially inner end portion of the side passage 50a is open in the compression chamber 51. A radially outer end portion of the side passage 50a is closed by the wall surface of the lower cylinder 50 in the radial direction and is open upwardly. As shown in Figure 6, the radially outer end portion of the side passage 50a is connected to the vertical passage 40a of the center plate 40 at the upward opening. Except at the opening, the side passage 50a is closed by the bottom surface of the central plate 40.

A suction passage including an upper suction passage (first passage) and a lower suction passage (second passage) branched from the upper suction passage (first passage) is formed in the rotary compressor 101 of the present embodiment. The upper suction passage supplies refrigerant to the compression chamber 31 of the upper cylinder 130. The lower suction passage supplies the refrigerant to the compression chamber 51 of the lower cylinder 50. In the present embodiment, the upper suction passage is constituted by (i) a horizontal passage from the front end of the suction pipe 6 to the radially inner end portion of the side passage 50a and the vertical passage 120b in the side passage 120a, which are formed in the upper head 120 and (ii ) the lateral passage 130a formed in the upper cylinder 130. The lower suction passage is constituted by the vertical passage 130b formed in the upper cylinder 130, the vertical passage 40a formed in the central plate 40 and the lateral passage 50a formed in the cylinder lower 50 (see figure 6).

To put it another way, the side passage 130a and the vertical passage 130b constitute the suction passage in the upper cylinder 130. The lateral passage 50a constitutes the suction passage in the lower cylinder 50. In the present embodiment, the surface area of a region facing the suction passage in the lower cylinder 50 is smaller than the surface area of a region facing the suction passage in the upper cylinder 130.

In the lower cylinder 50 in which the surface area of the region facing the suction passage is small compared to the upper cylinder 130, the decrease in temperature of the coolant around the region facing the suction passage is small compared to the upper cylinder 130. For this reason, a temperature difference between the lower cylinder 50 and the piston 52 provided in the compression chamber 51 of the lower cylinder 50 is small, with the result that the difference in the amount of dimensional change between the lower cylinder 50 and the piston 52 in thermal expansion is small.

Therefore, in the compressor 101 of the present embodiment, as shown in Figure 6, the difference between the height A3 of the lower cylinder 50 and the height A4 of the piston 52 in the compression chamber 51 of the lower cylinder 50 is less than the difference between the height A1 of the upper cylinder 130 and the height A2 of the piston 32 in the compression chamber 31 of the upper cylinder 130 (A3-A4≤A1-A2). The difference between the height A1 of the upper cylinder 130 and the height A2 of the piston 32 and the difference between the height A3 of the lower cylinder 50 and the height A4 of the piston 52 are those when the compressor 101 is not driven (i.e., at a normal temperature).

In the rotary compressor 101 of the present embodiment, a suction passage is formed including an upper suction passage and a lower suction passage branched from the upper suction passage. The upper suction passage supplies coolant to the compression chamber 31 of the upper cylinder 130. The upper suction passage supplies the coolant to the compression chamber 51 of the lower cylinder 50. The surface area of a region facing the suction passage in the lower cylinder 50 is smaller than the surface area of a region facing the suction passage in the upper cylinder 130. For this reason, compared to the upper cylinder 130, the decrease in the temperature of the coolant around the region facing the suction passage in the cylinder is small in the lower cylinder 50. For this reason, a temperature difference between the lower cylinder 50 and the piston 52 provided in the compression chamber 51 of the lower cylinder 50 is small, with the result that the difference in the amount of dimensional change between the lower cylinder 50 and the piston 52 upon thermal expansion is small. As a result, compared to the upper cylinder 130, problems are less likely to occur in the lower cylinder 50 even when the gaps between the end face in the axial direction of the piston 52 and the end faces in the axial direction of the plates ends 40 and 60 adjacent to piston 52 are narrow. This suppresses oil leakage from the inner periphery of the piston into the compression chamber and improves volume efficiency and indicated efficiency. Therefore, even when the two cylinders 130 and 50 are connected to the accumulator 5 by a single suction pipe 6 to reduce the size of the compressor 101, the decrease in efficiency of the compressor due to the increase in suction resistance is compensated by the improvement in volume efficiency and indicated efficiency, with the result that the decrease in compressor efficiency is suppressed. As such, reducing the size of the compressor 101 and suppressing the decrease in compressor efficiency are achieved in the present embodiment.

In the present embodiment, the upper suction passage (first passage) passes through the upper cylinder 130, but does not pass through the lower cylinder 50, while the lower suction passage (second passage) branches from the upper suction passage in the upper cylinder 130 and passes through both the upper cylinder 130 and the lower cylinder 50. With this arrangement, it is possible to easily construct the structure in which the surface area of the region facing the suction passage in the lower cylinder 50 is less than the surface area of the region facing the suction passage in the upper cylinder 130.

In addition to the above, in the present embodiment, the upper head 120, as an end plate, arranged on the opposite side of the lower cylinder 50 with respect to the upper cylinder 130, is configured to be inserted through the suction pipe 6, so that the front end of the suction pipe 6 is in the upper head 120. With this arrangement, the upper suction pipe has a portion in which the direction of travel of the refrigerant changes from vertical to horizontal in the upper cylinder 130, while The lower suction passage has a portion where the direction of travel of the refrigerant changes from vertical to horizontal in the lower cylinder 50. Therefore, the upper suction passage and the lower suction passage are unlikely to be significantly different between each other. yes in terms of suction resistance.

(Third Realization)

Next, a compressor of the third embodiment will be described with reference to Figure 7 and Figure 8. The compressor 201 of the third embodiment differs from the compressor of the first embodiment in that a lower cylinder 250 is configured to be inserted by a pipe suction 6 of an accumulator 5. In the present embodiment, structures identical to those of the first embodiment are indicated with the same reference symbols and may not be explained.

In the compressor 201 of the present embodiment, a driving mechanism 3 and a compression mechanism 204 are housed. As shown in Figure 7 and Figure 8, in the lower cylinder 250, a side passage 250a extending in The radial direction of the lower cylinder 250 is formed as a suction passage for introducing coolant into the compression chamber 51 of the lower cylinder 250. A radially inner end portion of the side passage 250a is open in the compression chamber 51, while a The radially outer end portion of the side passage 250a is open on the outer circumferential surface of the lower cylinder 250. The suction pipe 6 is inserted into the side passage 250a from the radially outer end portion of the side passage 250a, and a front end of the suction pipe 6 is around the center of the side passage 250a. In the lower cylinder 250, a vertical passage 250b extending vertically upward from the side passage 250a is formed as a suction passage for introducing refrigerant into the compression chamber 31 of an upper cylinder 230. The vertical passage 250b branches from a part of the side passage 250a, which is between the radially inner end portion of the side passage 250a and the front end of the suction pipe 6. The vertical passage 250b extends vertically upward and is open on the upper surface of the cylinder lower 250. Likewise, a vertical passage 250c extending vertically downward from the lateral passage 250a is formed in the lower cylinder 250. The vertical passage 250c branches from a portion of the lateral passage 250a, which is between the end portion radially interior of the side passage 250a and the front end of the suction pipe 6 (i.e., a part that vertically overlaps the vertical passage 250b). The vertical passage 250c extends vertically downward and is open in the lower surface of the lower cylinder 250. This opening is closed by the lower head 60.

In a center plate 240, a vertical passage 240a connected to the vertical passage 250b of the lower cylinder 250 is formed as a suction passage for introducing the refrigerant into the compression chamber 31. The vertical passage 240a connects the vertical passage 250b of the lower cylinder 250. to a lateral passage 230a described later of the upper cylinder 230.

In the upper cylinder 230 adjacent to the lower cylinder 250 through the center plate 240, the side passage 230a extending in the radial direction of the upper cylinder 230 is formed as a suction passage for introducing the refrigerant into the compression chamber 31 The side passage 230a is a cut formed in the lower surface of the upper cylinder 230. A radially inner end portion of the side passage 230a is open into the compression chamber 31. A radially outer end portion of the side passage 230a is closed by the upper cylinder wall surface 230 in the radial direction and is open downward. The radially outer end portion of the side passage 230a is connected to the vertical passage 240a of the center plate 240 at the downward opening. Except at the opening, the side passage 230a is closed by the upper surface of the central plate 240.

A suction passage including a lower suction passage (first passage) and an upper suction passage (second passage) branched from the lower suction passage (first passage) is formed in the rotary compressor 201 of the present embodiment. The lower suction passage supplies refrigerant to the compression chamber 51 of the lower cylinder 250. The upper suction passage supplies the refrigerant to the compression chamber 31 of the upper cylinder 230. In the present embodiment, the lower suction passage is a passage horizontally from the front end of the suction pipe 6 to the compression chamber 51 in the lateral passage 250a formed in the lower cylinder 250, while the upper suction passage is constituted by the vertical passage 250b formed in the lower cylinder 250, the vertical passage 240a formed in the central plate 240, and the lateral passage 230a formed in the upper cylinder 230.

To put it another way, in the lower cylinder 250, a horizontal passage from the front end of the suction pipe 6 to the compression chamber 51 in the side passage 250a (not including a part from the front end of the suction pipe 6 to the radially outer end portion of the side passage 250a of the side passage the passage 250a) and the vertical passage 250b constitute the suction passage. The side passage 230a constitutes the suction passage in the upper cylinder 230. In the present embodiment, the surface area of a region facing the suction passage in the upper cylinder 230 is smaller than the surface area of a region facing towards the suction passage in the lower cylinder 250.

In the upper cylinder 230 in which the surface area of the region facing the suction passage is small compared to the lower cylinder 250, the decrease in temperature of the coolant around the region facing the suction passage is small compared to the lower cylinder 250. For this reason, a temperature difference between the upper cylinder 230 and the piston 32 provided in the compression chamber 31 of the upper cylinder 230 is small, with the result that the difference in the amount of dimensional change between the upper cylinder 230 and the piston 32 in thermal expansion is small.

Therefore, in the compressor 201 of the present embodiment, as shown in Figure 8, the difference between the height A1 of the upper cylinder 230 and the height A2 of the piston 32 in the compression chamber 31 of the upper cylinder 230 is less than the difference between the height A3 of the lower cylinder 250 and the height A4 of the piston 52 in the compression chamber 51 of the lower cylinder 250 (A1-A2≤A3-A4). The difference between the height A3 of the lower cylinder 250 and the height A4 of the piston 52 and the difference between the height A1 of the upper cylinder 230 and the height A2 of the piston 32 are those when the compressor 201 is not driven (i.e., at a normal temperature).

A suction passage including a lower suction passage and an upper suction passage branched from the lower suction passage is formed in the rotary compressor 201 of the present embodiment. The lower suction passage supplies coolant to the compression chamber 51 of the lower cylinder 250. The upper suction passage supplies the coolant to the compression chamber 31 of the upper cylinder 230. The surface area of a region facing the suction passage in the upper cylinder 230 is smaller than the surface area of a region facing the suction passage in the lower cylinder 250. For this reason, compared to the lower cylinder 250, the decrease in the temperature of the coolant around the region facing the suction passage in the cylinder is small in the upper cylinder 230. For this reason, a temperature difference between the upper cylinder 230 and the piston 32 provided in the compression chamber 31 of the upper cylinder 230 is small, with the result that the difference in the amount of dimensional change between the upper cylinder 230 and the piston 32 upon thermal expansion is small. As a result, compared to the lower cylinder 250, problems are less likely to occur in the upper cylinder 230 even when the gaps between the end face in the axial direction of the piston 32 and the end faces in the axial direction of the plates end 20 and 240 adjacent to piston 32 are narrow. This suppresses oil leakage from the inner periphery of the piston into the compression chamber and improves volume efficiency and indicated efficiency. Therefore, even when the two cylinders 230 and 250 are connected to the accumulator 5 by a single suction pipe 6 to reduce the size of the compressor 201, the decrease in efficiency of the compressor due to the increase in suction resistance is compensated by the improvement in volume efficiency and indicated efficiency, with the result that the decrease in compressor efficiency is suppressed. As such, reducing the size of the compressor 201 and suppressing the decrease in compressor efficiency are achieved in the present embodiment.

In the present embodiment, the lower suction passage (first passage) passes through the lower cylinder 250, but does not pass through the upper cylinder 230, while the upper suction passage (second passage) branches from the lower suction passage in the lower cylinder 250 and passes through the lower cylinder 250 and the upper cylinder 230. With this arrangement, it is possible to easily construct the structure in which the surface area of the region facing the suction passage in the upper cylinder 230 is less than the surface area of the region facing the suction passage in the lower cylinder 250.

In addition to the above, in the present embodiment, the lower cylinder 250 is configured to be inserted by the suction pipe 6 so that the front end of the suction pipe 6 is provided inside the lower cylinder 250. With this arrangement, the passage of the refrigerant from the front end of the suction pipe 6 to the compression chamber 51 of the lower cylinder 250 is constituted only by the linear side passage 250a, with the result that the increase in suction resistance is suppressed.

[Verification test with real machines]

The results of a test carried out with rotary compressors are described below. As described above, in the rotary compressor of the present invention, the difference between the cylinder height and the piston height is arranged to be small in the second cylinder compared to the first cylinder, with the result that they are suppressed. oil leaks from the inner periphery of the piston to the compression chamber and thus the efficiency of the compressor is improved. The smaller the difference between the cylinder height and the piston height, the better the efficiency of the compressor. However, seizure due to sliding friction between the piston and end plate tends to occur and reliability decreases. To put it another way, when the difference between the cylinder height and the piston height is large, reliability improves as seizure is less likely to occur due to sliding friction between the piston and the end plate, but the efficiency of the compressor deteriorates.

Under this circumstance, the inventors of the present invention carried out a verification test using plural rotary compressors (including those of different types) to test whether the allowable efficiency of the compressor was obtained while ensuring reliability. In this test, the following variables were used: the height Hc (mm) of a cylinder in the axial direction of a transmission shaft; the height Hp (mm) of a piston provided in a compression chamber formed in the cylinder, in the axial direction; the surface area As (mm2) of a region facing a suction passage in the cylinder; and the length Ls (mm) of the suction passage in the cylinder. The length Ls is the length of the suction passage in a plane orthogonal to the axial direction of the drive shaft, and is equivalent to the length in the radial direction of the cylinder in the above embodiments. Examples of length Ls are indicated as L1 and L2 in Figure 3, Figure 6 and Figure 8.

As for each of the compressors that were different in the four variables Hc described above, Hp, As and Ls, it was evaluated whether seizure occurred due to sliding friction between the piston and an end plate and whether the allowable efficiency was obtained. of the compressor. Figure 9 is a graph showing the test results.

In Figure 9, the parameter on the vertical axis indicates (height difference between cylinder and piston (Hc-Hp)/cylinder height Hc), that is, a rate of change of the cylinder height with respect to the variation of temperature. As the coolant decreases in temperature around the region facing the suction passage in the cylinder, the cylinder thermally contracts, with the result that the piston height difference (Hc-Hp) is reduced. When the difference becomes zero, the piston gets stuck between the end plates and seizure occurs and thus the compressor may be damaged. The higher the parameter on the vertical axis, the less likely seizure is to occur.

The parameter on the horizontal axis indicates (area As of the region in front of the suction passage in the cylinder/height of the cylinder Hp x length Ls of the suction passage in the longitudinal direction), that is, the probability of temperature variation of the cylinder. The greater the surface area of the region facing the suction passage in the cylinder, the more easily the cylinder temperature drops due to cooling by the coolant. Meanwhile, the greater the height of the cylinder and the length of the suction duct in the longitudinal direction, the less easily the cylinder temperature drops due to the increase in heat capacity. As such, the temperature around the region facing the suction passage in the cylinder varies according to the balance of the surface area As of the region, the height of the cylinder Hp and the length Ls of the suction passage in the longitudinal direction .

In Figure 9, an approximate line A which is represented as a linear line is a limit line indicating the minimum performance in terms of compressor efficiency. The allowable efficiency of the compressor is obtained in a region below the approximate line A. Meanwhile, an approximate line B which is represented as a linear line with the same inclination as the approximate line A is a limit line indicating minimum reliability (without seizure). Seizure does not occur in a region above approximate line B. Approximate line A is expressed as follows:

(Hc-Hp)/Hc=1.4x0.0001 xAs/(Hc-Ls)+6.7x0.0001

The approximate line B is expressed as follows:

(Hc-Hp)/Hc=1.4x0.0001 xAs/(Hc-Ls)+3.9x0.0001

For this reason, when the four variables Hc described above, Hp, As, and Ls meet a relationship 3.9x0.0001 ≤(Hc-Hp)/Hc-1.4x0.0001xAs/(HcLs)≤6.7x0.0001 , you get a compressor that is sufficient in both compressor efficiency and reliability.

[Modifications]

In the first embodiment above, the first cylinder may be a lower cylinder 50 and the second cylinder may be an upper cylinder 30. In other words, the surface area of a region facing the suction conduit in the upper cylinder 30 may be less than the surface area of a region facing the suction passage in the lower cylinder 50. Likewise, in the second embodiment, the first cylinder may be a lower cylinder 50 and the second cylinder may be an upper cylinder 130. Stated another way, the surface area of a region facing the suction passage in the upper cylinder 130 may be less than the surface area of a region facing the suction passage in the lower cylinder 50. Likewise, In the third embodiment, the first cylinder may be an upper cylinder 230 and the second cylinder may be a lower cylinder 250. In other words, the surface area of a region facing the suction conduit in the lower cylinder 250 may be less than the surface area of a region facing the suction passage in the upper cylinder 230.

The arrangements (e.g., design and cross-sectional shape) of the suction passage may be different from those described in the first to third embodiments. For example, while in the first to third embodiments the side passages 30a, 50a, 130a, 230a and 250a extend in the radial direction of the cylinder, these side passages may extend in any direction in the plane orthogonal to the axial direction of the shaft. transmission, provided that they communicate with the compression chamber.

While in the first to third embodiments the accumulator attached to the rotary compressor of the present invention is taken as an example of the external device, the external device is not limited to this. The external device may be an accumulator not attached to the rotary compressor of the present invention or a device (e.g., an evaporator) that is not an accumulator, for example.

While in the first to third embodiments the roller and vane of the piston are integrated, the roller and vane may be independent of each other.

While the first to third embodiments describe the 2-cylinder rotary compressor including the upper cylinder and the lower cylinder, the rotary compressor may include three or more cylinders. In this case, in each of the three or more cylinders, the difference between the height of a cylinder in the axial direction of a transmission shaft and the height of a piston provided in a compression chamber of the cylinder in the axial direction preferably decreases as the surface area of a region facing a suction passage in the cylinder decreases. Thus, embodiments of the present invention have been described above. However, the specific structure of the present invention should not be construed to be limited to the embodiments described above. The scope of the present invention is not defined by the foregoing embodiments, but by the claims set forth below, and shall encompass all modifications within the scope of the claims.

[List of reference signs]

1, 201 rotary compressor

3 drive mechanism

4, 204 compression mechanism

20, 120 top header (end plate)

30, 130, 230 upper cylinder (cylinder, first cylinder)

31.51 compression chamber

32, 52 piston

40, 240 center plate (end plate)

50, 250 lower cylinder (cylinder, second cylinder)

60 bottom header (end plate)

Claims (6)

1. A rotary compressor (1; 101; 201) comprising a compression mechanism (4; 104; 204) and a drive mechanism (3) including a drive shaft (3b) that drives the compression mechanism (4 ; 104; 204), the compression mechanism (4; 104; 204) and the drive mechanism (3) being housed in the rotary compressor (1; 101; 201), including compression mechanism (4; 104; 204): a plurality of cylinders (30, 50; 50, 130; 230, 250) in which compression chambers (31, 51) are formed, respectively, the cylinders (30, 50; 50, 130; 230, 250) being aligned in the axial direction of the transmission shaft (3b), so that the transmission shaft (3b) is inside the compression chambers (31,51); a plurality of end plates (20, 40, 60; 40, 60, 120; 20, 60, 240) provided at both ends of the cylinders (30, 50; 50, 130; 230, 250) in the axial direction to define the compression chambers (31,51); and a plurality of pistons (32, 52) provided in the respective compression chambers (31, 51) and driven by the transmission shaft (3b), wherein the cylinders (30, 50; 50, 130; 230, 250) include a first cylinder (30; 130; 250) and a second cylinder (50; 50; 230) adjacent to the first cylinder (30; 130; 250) through one of the end plates (20, 40, 60; 40, 60, 120; 20, 60, 240), a suction step including a first step (30a; 120a, 120b, 130a; 250a) and a second step (30b, 40a, 50a; 130b, 40a, 50a; 250b, 240a, 230a) branching from the first step (30a ; 120a, 120b, 130a; 250a) is formed in the rotary compressor (1; 101; 201), the first step feeds the compression chamber (31; 31; 51) of the first cylinder (30; 130; 250) with refrigerant from an external device through a suction pipe (6), and the second pass (30b, 40a, 50a; 130b, 40a, 50a; 250b, 240a, 230a) feeds the compression chamber (51; 51; 31) of the second cylinder (50; 50; 230) with the coolant, characterized by the surface area of a region facing the suction passage in the second cylinder (50; 50; 230) is less than the surface area of a region facing the suction passage in the first cylinder (30; 130; 250 ), and a difference between the height (A3; A3; A1) of the second cylinder (50; 50; 230) in the axial direction and the height (A4; A4; A2) in the axial direction of the piston (52; 52; 32) arranged in the compression chamber (51; 51; 31) of the second cylinder (50; 50; 230) is less than a difference between the height (A1; A1; A3) of the first cylinder (30; 130; 250) in the direction axial and height (A2; A2; A4) in the axial direction of the piston (32; 32; 52) arranged in the compression chamber (31; 31; 51) of the first cylinder (30; 130; 250). 2. The rotary compressor (1; 101; 201) according to claim 1, wherein The first pass (30a; 120a, 120b, 130a; 250a) passes through the first cylinder (30; 130; 250), but does not pass through the second cylinder (50; 50; 230), and the second pass (30b, 40a , 50a; 130b, 40a, 50a; 250b, 240a, 230a) branches from the first step (30a; 120a, 120b, 130a; 250a) in the first cylinder (30; 130; 250) and passes both through the first cylinder (30; 130; 250) and for the second cylinder (50; 50; 230). 3. The rotary compressor (1) according to claim 2, wherein the first cylinder (30) is configured to be inserted through the suction pipe (6), so that a front end of the suction pipe (6) is in the first cylinder (30). 4. The rotary compressor (101) according to claim 2, wherein an end plate (120) arranged on the opposite side of the second cylinder (50) with respect to the first cylinder (130) is configured to be inserted through the suction pipe (6), so that a front end of the suction pipe (6) is on the end plate (120). 5. The rotary compressor (1; 101; 201) according to any one of claims 1 to 4, wherein, the height of the cylinder (30, 50; 50, 130; 230, 250) in the axial direction is less different from the height in the axial direction of the piston (32, 52) provided in the compression chamber (31,51) of the cylinder (30, 50; 50, 130; 230, 250), when the surface area of a region facing The suction passage in the cylinder (30, 50; 50, 130; 230, 250) is smaller. 6. The rotary compressor (1; 101; 201) according to any one of claims 1 to 5, wherein, the first passage (30a; 120a, 120b, 130a; 250a) extends in the radial direction of the first cylinder (30 ; 130; 250) in the first cylinder (30; 130; 250), and the second step (30b, 40a, 50a; 130b, 40a, 50a; 250b, 240a, 230a) includes a vertical step (30b; 130b; 250b ) branched from the first passage (30a; 120a, 120b, 130a; 250a) into the first cylinder (30; 130; 250) and extends in the axial direction and a lateral passage (50a; 50a; 230a) extends in the radial direction of second cylinder (50; 50; 230) in the second cylinder (50; 50; 230), In each of the cylinders (30, 50; 30, 130; 230, 250), a relationship 3.9x0.0001 ≤(Hc-Hp)/Hc-1.4x0.0001 xAs/(Hc-Ls) is met. ≤6.7x0.0001, where the height of the cylinder in the axial direction is denoted as Hc (mm), the height in the axial direction of the piston provided in the compression chamber in the cylinder is denoted as Hp (mm), the Surface area of a region facing the suction passage in the cylinder is denoted as As (mm2) and the length of the suction passage in the cylinder in the radial direction of the cylinders (30, 50; 30, 130; 230, 250) is denoted as Ls (mm).