Device having a pulsation reducing structure, a passage forming body and compressor

Abstract

Pulsation of gas spreads from a pulsation source to a gas passage in a device. A muffler is located in a part of the gas passage. A combined passage is located upstream or downstream of the muffler with respect to a flowing direction of gas. The combined passage includes a restricting passage and a pressure restoring passage, which are connected in series. The pressure restoring passage is located downstream of the restricting passage with respect to the flowing direction of gas. The muffler is located between the pulsation source and the combined passage in the gas passage. Therefore, the device obtains sufficient pulsation reducing effect and suppresses pressure loss.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a device having a pulsation reducing structure. The present invention also pertains to a passage forming body and a compressor.

In a scroll compressor disclosed in Japanese Laid-Open Patent Publication No. 2002-285981, an oil separator is located in a front housing member. An oil separating chamber, which forms part of the oil separator, is connected to a discharge chamber defined at the back of a fixed scroll. The oil separating chamber accommodates a cylindrical member, which forms part of the oil separator. Refrigerant gas in the discharge chamber is introduced into the oil separating chamber. Lubricant oil included in the refrigerant gas introduced into the oil separating chamber is separated from the refrigerant gas.

The cylindrical member, which forms part of the oil separator, also functions to reduce pulsation of discharged gas.

The inner diameter of the cylindrical member needs to be reduced to obtain sufficient pulsation reducing effect. However, if the inner diameter of the cylindrical member is excessively reduced, a great pressure loss is generated. Therefore, it is difficult to reduce the inner diameter of the cylindrical member to obtain sufficient pulsation reducing effect.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide a device having a pulsation reducing structure that obtains sufficient pulsation reducing effect and suppresses pressure loss in devices having a gas passage. The present invention also pertains to a passage forming body and a compressor.

To achieve the above-mentioned objective, the present invention provides a device having a pulsation reducing structure. The device includes a gas passage, a pulsation source connected to the gas passage, a muffler for reducing the pulsation and a combined passage located in the gas passage. Pulsation of gas spreads from the pulsation source to the gas passage. The muffler is located in a part of the gas passage. The combined passage is located upstream or downstream of the muffler with respect to a flowing direction of gas. The combined passage includes a restricting passage and a pressure restoring passage. The restricting passage and the pressure restoring passage are connected in series. The pressure restoring passage is located downstream of the restricting passage with respect to the flowing direction of gas. The muffler is located between the pulsation source and the combined passage in the gas passage.

According to another aspect of the invention, a passage forming body having a plurality of combined passages is provided. The combined passages are arranged in parallel. Each combined passage includes a restricting passage and a pressure restoring passage. In each combined passage, the restricting passage is combined with the pressure restoring passage in series.

In addition, present invention may be applicable to provide a scroll compressor. The compressor includes a compression mechanism including a movable scroll and a fixed scroll, the scrolls defining a compression chamber, a discharge chamber for receiving gas discharged from the compression chamber, a discharge gas passage for guiding discharge gas from the discharge chamber to the outside of the compressor. A restricting passage is located in the discharge gas passage. A pressure restoring passage is located in the discharge gas passage. The pressure restoring passage is connected to the restricting passage in series and located downstream of the restricting passage with respect to a flowing direction of gas.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1(a) is a cross-sectional view illustrating a compressor according to a first embodiment of the present invention;

FIG. 1(b) is an enlarged partial cross-sectional view of FIG. 1(a);

FIG. 2(a) is a cross-sectional view illustrating a compressor according to a second embodiment of the present invention;

FIG. 2(b) is an enlarged partial cross-sectional view of FIG. 2(a);

FIG. 3 is an enlarged partial cross-sectional view illustrating a third embodiment of the present invention;

FIG. 4 is a partial cross-sectional view illustrating a fourth embodiment of the present invention;

FIG. 5(a) is a partial cross-sectional view illustrating a fifth embodiment of the present invention;

FIG. 5(b) is a side view illustrating a passage forming body 66 shown in FIG. 5(a); and

FIG. 5(c) is a cross-sectional view taken along line VC-VC in FIG. 5(b).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, like numerals are used for like elements throughout.

A first embodiment of the present invention will now be described with reference to FIGS. 1(a) and 1(b).

As shown in FIG. 1(a), a scroll compressor 10 includes a rear housing member 12 and a front housing member 31. A shaft support member 13 and a fixed scroll 11 are inserted in and fixed to the rear housing member 12. The front housing member 31 is secured to the rear housing member 12 and the fixed scroll 11. The rear housing member 12 and the front housing member 31 form a housing of a device, which is the scroll compressor 10. The rear housing member 12 and the shaft support member 13 rotatably support a rotary shaft 14 by means of radial bearings 15, 16.

The rotary shaft 14 extends through the shaft support member 13 and projects toward the fixed scroll 11. An eccentric shaft 17 is formed integrally with the end of the rotary shaft 14 that projects from the shaft support member 13. The axis of the eccentric shaft 17 located at a position decentered from the axis of the rotary shaft 14. The eccentric shaft 17 supports a bush 18 to which a balance weight 19 is integrally formed. The bush 18 supports a movable scroll 20 by means of a radial bearing 21 such that the movable scroll 20 faces the fixed scroll 11. The movable scroll 20 rotates relative to the fixed scroll 11. The radial bearing 21 is accommodated in a cylindrical portion 221, which projects from the rear surface of a movable scroll base plate 22 of the movable scroll 20.

The fixed scroll 11 includes a fixed scroll base plate 23 and a fixed volute portion 24. The movable scroll 20 includes the movable scroll base plate 22 and a movable volute portion 25. The fixed scroll base plate 23, the fixed volute portion 24, the movable scroll base plate 22, and the movable volute portion 25 define sealed spaces S0 and S1. The movable scroll 20 orbits as the eccentric shaft 17 rotates. Centrifugal force created by the orbital movement of the movable scroll 20 is cancelled by the balance weight 19.

Columnar anti-rotation pins 27 (three or more) are fixed to the movable scroll base plate 22. The shaft support member 13 has circular anti-rotation bores 131, the number of which is the same as the anti-rotation pins 27. The anti-rotation bores 131 are arranged in the circumferential direction of the shaft support member 13. The end of each anti-rotation pin 27 is inserted in the corresponding anti-rotation bore 131.

A stator 29 is secured to the inner circumferential surface of the rear housing member 12. A rotor 30 is secured to the rotary shaft 14. When electricity is supplied to a stator coil 291 of the stator 29, the rotor 30 and the rotary shaft 14 rotate integrally. The stator 29 and the rotor 30 construct an electric motor.

The movable scroll 20 orbits as the eccentric shaft 17 rotates integrally with the rotary shaft 14. An inlet 26 is formed in a circumferential wall of the rear housing member 12 and a circumferential wall 111 of the fixed scroll 11. As the movable scroll 20 orbits, refrigerant gas in an external refrigerant circuit, which is not shown, is introduced into a suction chamber 112 inside the circumferential wall 111 through the inlet 26. The refrigerant gas introduced into the suction chamber 112 flows into the sealed spaces S0, S1 between the fixed scroll base plate 23 and the movable scroll base plate 22 from the periphery of the fixed scroll 11 and the movable scroll 20. Lubricant oil is included in a refrigeration circuit, which includes the compressor 10, and flows with refrigerant gas.

As the movable scroll 20 orbits, the circumferential surface of each anti-rotation pin 27 slides along the circumferential surface of the corresponding anti-rotation bore 131. The movable scroll 20 is prevented from rotating while being permitted to orbit. As the movable scroll 20 orbits, the sealed spaces S1, S0 move toward the center of the scrolls 11, 20, while the volume of each sealed space S1, S0 decreasing.

A discharge chamber 32 is formed in the front housing member 31. The refrigerant gas compressed by the decrease in the volume of the sealed spaces S1, S0 is discharged to the discharge chamber 32 through a discharge port 231, which is formed in the fixed scroll base plate 23, while flexing a discharge valve flap 33. A retainer 34 limits the opening degree of the discharge valve flap 33. A compression reaction force in the sealed spaces S1, S0 that acts on the movable scroll 20 is received by the shaft support member 13.

An outlet 311 is formed in the circumferential wall of the front housing member 31. A pipe 35 is fitted to the outlet 311. That is, the pipe 35 is formed separately from the front housing member 31, which defines the discharge chamber 32 and the outlet 311. As shown in FIG. 1(b), the pipe 35 includes a fitting portion 351, a restrictor 38, and a diffuser 39. The restrictor 38, the diffuser 39, and the fitting portion 351 are arranged in series in this order along a flowing direction of refrigerant gas from the discharge chamber 32 to the outside of the compressor 10 via the outlet 311. In other words, a restricting passage 381 in the restrictor 38 and a pressure restoring passage 391 in the diffuser 39 are connected in series in this order from the discharge chamber 32 toward the outside of the compressor 10. The cross-sectional area of the pressure restoring passage 391 is greater than the cross-sectional area of the restricting passage 381.

The pipe 35 is fitted to the outlet 311 with the fitting portion 351. The inner diameter of the fitting portion 351 is greater than the inner diameter of the diffuser 39 and the restrictor 38. The inner diameter of the restrictor 38 is constant. The inner diameter of the diffuser 39 gradually increases from the end close to the restrictor 38 toward the end close to the fitting portion 351. That is, the pressure restoring passage 391 is widened in the flowing direction of refrigerant gas. The widening angle θ1 (see FIG. 1(b)) of the pressure restoring passage 391 of the diffuser 39 is less than or equal to 20 degrees.

When refrigerant gas is discharged into the discharge chamber 32 through the discharge port 231 while flexing the discharge valve flap 33, the refrigerant gas collides with the inner wall of the front housing member 31, or the refrigerant gas changes the flowing direction and flows toward the pipe 35. Therefore, the lubricant oil included in the refrigerant gas is separated from the refrigerant gas. The lubricant oil separated from the refrigerant gas is stored at the bottom of the discharge chamber 32. The bottom of the discharge chamber 32 is connected to a back pressure chamber 37 located at the back of the movable scroll base plate 22 via a return passage 36. The lubricant oil stored at the bottom of the discharge chamber 32 is supplied to the back pressure chamber 37 through the return passage 36 and used to lubricate the radial bearings 16 and 21. Refrigerant gas in the discharge chamber 32 flows to the external refrigerant circuit through the pipe 35.

The pipe 35 is suspended in the outlet 311 such that the lower end of the pipe 35 is separate from the inner wall of the front housing member 31 and projects in the discharge chamber 32. That is, part of the pipe 35 is located inside the discharge chamber 32. This structure effectively prevents lubricant oil adhered to the inner wall of the front housing member 31 from entering the pipe 35 by the operation of the refrigerant gas. That is, the pipe 35 functions as an oil separator, which separates lubricant oil from refrigerant gas.

As shown in FIGS. 1(a) and 1(b), the discharge port 231 and the discharge chamber 32 are part of a gas passage in the compressor 10. The discharge chamber 32 functions as a muffler that is part of the gas passage. The restricting passage 381 in the restrictor 38 and the pressure restoring passage 391 in the diffuser 39 form a combined passage 40 located downstream of the muffler, which is the discharge chamber 32 in this embodiment, in respect to the gas passage. The pressure restoring passage 391, which forms part of the combined passage 40, is located downstream of the restricting passage 381. The fixed scroll 11, the movable scroll 20, and the sealed spaces S0, S1 form a pulsation source. The pulsation of discharge gas spreads from the pulsation source to the external refrigerant circuit via the discharge chamber 32 and the combined passage 40. The discharge chamber 32 (muffler) and the restricting passage 381 reduce the pulsation of discharge gas. The muffler, which is the discharge chamber 32 in this embodiment, is located between the pulsation source and the combined passage 40 in respect to the gas passage.

The first embodiment has the following advantages.

(1-1) In the restricting passage 381, the pressure of refrigerant gas is reduced as the flow rate of refrigerant gas increases. On the other hand, the pressure of refrigerant gas that has moved from the restricting passage 381 to the pressure restoring passage 391 increases as the flow rate of refrigerant gas is reduced in the pressure restoring passage 391. That is, the pressure restoring passage 391 restores the pressure of refrigerant gas that has passed through the restricting passage 381. The pressure of refrigerant gas can be reduced in the restricting passage 381 by an amount that can be restored in the pressure restoring passage 391. Therefore, the cross-sectional area of the restricting passage 381 can be reduced to increase the pulsation reducing effect of the discharge gas.

(1-2) The pipe 35, which is provided with the combined passage 40, is fitted to the outlet 311 of the front housing member 31. In this case, the pipe 35 may be press-fitted or adhered with an adhesion to the outlet 311. The pipe 35 is fitted to a gas passage (the outlet 311 in this embodiment) the diameter of which is greater than or equal to the maximum outer diameter of the diffuser 39 by adjusting the outer diameter of the fitting portion 351 to the diameter of the gas passage. The pipe 35 is easily formed by, for example, press working. Therefore, the size and the shape of the pipe 35 to which the combined passage 40 is formed can be selected in accordance with the shape of a pipe used for the gas passage (the outlet 311 in this embodiment). Thus, the restricting passage 381 and the pressure restoring passage 391 are also easily formed. Therefore, the pipe 35 is a favorable place for forming the combined passage 40.

(1-3) The pipe 35 functions also as the oil separator. Forming the combined passage 40 in the pipe 35, which functions as the oil separator, reduces the number of parts as compared to a case in which a pipe dedicated for pulsation reduction is used. This contributes to reducing the cost. Since a space for the pipe dedicated for pulsation reduction is unnecessary, the size of the compressor 10 is prevented from being increased.

(1-4) In restoring the pressure in the pressure restoring passage 391, it is important that the flow of refrigerant gas through the pressure restoring passage 391 does not separate from the inner surface of the diffuser 39. The structure of setting the widening angle θ1 of the pressure restoring passage 391 to be less than or equal to 20 degrees is effective in preventing the refrigerant gas flow from separating from the inner surface.

(1-5) The compressor 10 that causes pulsation of discharge gas is a device that includes the muffler, which is the discharge chamber 32 in this embodiment, as part of a gas passage. The present invention is suitable for such compressor 10.

A pulsation reduction structure according to a second embodiment of the present invention will now be described with reference to FIGS. 2(a) and 2(b).

As shown in FIG. 2(a), a cylinder block 41, a front housing member 42, and a rear housing member 43 form a housing of a device, which is a piston type variable displacement compressor 44 in the second embodiment. The front housing member 42 and the cylinder block 41 define a control pressure chamber 421. The front housing member 42 and the cylinder block 41 rotatably support a rotary shaft 45.

A rotary support 46 is fixed to the rotary shaft 45, and a swash plate 47 is supported on the rotary shaft 45. The swash plate 47 is permitted to incline with respect to and slide along the rotary shaft 45. Guide holes 461 are formed in the rotary support 46 and guide pins 48 are connected to the swash plate 47. Each guide pin 48 is fitted to one of the guide holes 461 to form a hinge mechanism. The hinge mechanism permits the swash plate 47 to tilt with respect to the axial direction of the rotary shaft 45 and rotate integrally with the rotary shaft 45.

When the center of the swash plate 47 moves toward the rotary support 46, the inclination of the swash plate 47 increases. The rotary support 46 determines the maximum inclination of the swash plate 47. The swash plate 47 shown by a solid line in FIG. 2(a) is in the maximum inclination state. When the center of the swash plate 47 moves toward the cylinder block 41, the inclination of the swash plate 47 decreases. The swash plate 47 shown by a chain double-dashed line in FIG. 2(a) is in the minimum inclination state.

Cylinder bores 411 (only one is shown) extend through the cylinder block 41. Each cylinder bore 411 accommodates a piston 49. The rotation of the swash plate 47 is converted to reciprocation of the pistons 49 by means of shoes 50. Thus, each piston 49 reciprocates in the corresponding cylinder bore 411.

A suction chamber 431 and a discharge chamber 432 are defined in the rear housing member 43. Suction ports 511 are formed in a valve plate 51 and a valve flap plate 53. Discharge ports 512 are formed in the valve plate 51 and a valve flap plate 52. Suction valve flaps 521 are formed on the valve flap plate 52, and discharge valve flaps 531 are formed on the valve flap plate 53. As each piston 49 moves from the top dead center to the bottom dead center (from the right side to the left side in FIG. 2(a)), refrigerant gas in the suction chamber 431 is drawn into the corresponding suction port 511 while flexing the suction valve flap 521 to enter the associated cylinder bore 411. When each piston 49 moves from the bottom dead center to the top dead center (from the left side to the right side in FIG. 2(a)), refrigerant in the corresponding cylinder bore 411 is discharged to the discharge chamber 432 via the corresponding discharge port 512 while flexing the discharge valve flap 531.

The discharge chamber 432 is connected to the control pressure chamber 421 with a supply passage 54. The control pressure chamber 421 is connected to the suction chamber 431 with a release passage 55. Refrigerant in the control pressure chamber 421 flows to the suction chamber 431 through the release passage 55.

An electromagnetic control valve 56 is located in the supply passage 54. The control valve 56 is closed when de-excited and prevents refrigerant from passing through. In this state, refrigerant is not supplied from the discharge chamber 432 to the control pressure chamber 421 via the supply passage 54. Refrigerant in the control pressure chamber 421 flows to the suction chamber 431 through the release passage 55. Therefore, the pressure in the control pressure chamber 421 decreases. Therefore, the inclination angle of the swash plate 47 increases. The compressor displacement increases, accordingly. The control valve 56 is open when excited and permits refrigerant through. In this state, refrigerant is supplied from the discharge chamber 432 to the control pressure chamber 421 via the supply passage 54. Therefore, the pressure in the control pressure chamber 421 increases. Accordingly, the inclination angle of the swash plate 47 decreases, which decreases the compressor displacement.

A muffler 57 is formed on the circumferential surface of the cylinder block 41 and the circumferential surface of the front housing member 42. The muffler 57 has a cylindrical portion 58. The cylindrical portion 58 is formed integrally with the cylinder block 41. The muffler 57 is connected to the discharge chamber 432 via a discharge passage 59. The muffler 57 is connected to the control pressure chamber 421 via an oil passage 60. A pipe 61 is accommodated in and fitted to the cylindrical portion 58.

As shown in FIG. 2(b), the pipe 61 includes a nozzle 62, a restrictor 63, and a diffuser 64. The nozzle 62, the restrictor 63, and the diffuser 64 are arranged in series in this order along a direction from the muffler 57 toward the outside of the compressor 44 via the interior of the cylindrical portion 58. In other words, an introduction passage 621 in the nozzle 62, a restricting passage 631 in the restrictor 63, and a pressure restoring passage 641 in the diffuser 64 are connected in series in this order from the muffler 57 toward the outside of the compressor 44. The inner diameter of the nozzle 62 gradually decreases from the end close to the muffler 57 toward the restrictor 63. A small diameter portion of the introduction passage 621 is connected to the restricting passage 631. That is, the introduction passage 621 is tapered toward the restricting passage 631. In other words, assuming that the introduction passage 621 is the inlet of the restricting passage 631, the inlet is widened in a direction opposite to the flowing direction of refrigerant gas.

The inner diameter of the restrictor 63 is constant, and the inner diameter of the diffuser 64 gradually increases from the end close to the restrictor 63 toward the end close to the outside of the compressor 44. The widening angle θ1 (see FIG. 2(b)) of the diffuser 64 is less than or equal to 20 degrees. The widening angle θ2 (see FIG. 2(b)) of the nozzle 62 is greater than the widening angle θ1 of the diffuser 64. The inner circumferential surface of the nozzle 62 is connected to the inner circumferential surface of the cylindrical portion 58 in a bent state as shown by an acute angle α in FIG. 2(b). That is, there is no step having a substantially right angle between the inner circumferential surface of the nozzle 62 and the inner circumferential surface of the cylindrical portion 58.

When refrigerant gas is discharged into the muffler 57 through the discharge passage 59, the refrigerant gas collides with the inner wall of the muffler 57, or the refrigerant gas changes the flowing direction and flows toward the cylindrical portion 58. Therefore, the lubricant oil included in the refrigerant gas is separated from the refrigerant gas. The passage of refrigerant gas extending from the muffler 57 to the cylindrical portion 58 narrows in the cylindrical portion 58. This prevents lubricant oil from entering the cylindrical portion 58. That is, the cylindrical portion 58 functions as an oil separator, which separates lubricant oil from refrigerant gas. The lubricant oil separated from the refrigerant gas is stored at the bottom of the muffler 57. Refrigerant gas in the muffler 57 flows to the external refrigerant circuit, which is not shown, through the pipe 61.

The discharge passage 59 and the muffler 57 are part of the gas passage in the variable displacement compressor 44. The restricting passage 631 in the restrictor 63 and the pressure restoring passage 641 in the diffuser 64 form a combined passage 65 located downstream of the muffler 57 in respect to the gas passage. The pressure restoring passage 641, which forms part of the combined passage 65, is located downstream of the restricting passage 631. The pipe 61 is located in the cylindrical portion 58 to permit refrigerant gas to flow through the combined passage 65.

The pistons 49 and the cylinder bores 411 construct a pulsation source. The pulsation of discharge gas spreads from the pulsation source to the external refrigerant circuit via the discharge chamber 432, the discharge passage 59, the muffler 57, and the combined passage 65. The muffler 57 and the restricting passage 631 reduce the pulsation of discharge gas. The muffler 57 is located between the pulsation source and the combined passage 65 in respect to the gas passage.

The second embodiment has the same advantages as the advantages (1-1), (1-4), and (1-5) of the first embodiment. The pipe 61 can be fitted to the cylindrical portion 58 by setting the outer diameter of the pipe 61 in accordance with the inner diameter of the cylindrical portion 58. The size and the shape of the pipe 61 to which the combined passage 65 is formed can be selected in accordance with the shape of the pipe used for the gas passage (the cylindrical portion 58 in the second embodiment). Therefore, the pipe 61 is a favorable place for forming the combined passage 65.

In the second embodiment, the pipe 61 is accommodated in the cylindrical portion 58. Therefore, if there is a step having a substantially right angle at the inlet of the pipe 61, the step generates a great passage resistance with respect to the refrigerant gas. The passage resistance causes pressure loss. However, the inner circumferential surface of the nozzle 62 is connected to the inner circumferential surface of the cylindrical portion 58 at an acute angle α. Therefore, the passage resistance applied to the refrigerant gas that flows into the pipe 61 is small.

FIG. 3 shows a third embodiment of the present invention. As shown in FIG. 3, a pipe 61A includes a pressure restoring passage 641A, which is formed by smoothly connecting the inner circumferential surface of a diffuser 64A to the inner circumferential surface of the restrictor 63. In this case, the widening angle θ3 of the pressure restoring passage 641A, which forms part of a combined passage 65A, represents the angle at the maximum diameter portion of the pressure restoring passage 641A. The widening angle θ3 of the pressure restoring passage 641A is less than or equal to 20 degrees.

A fourth embodiment will now be described with reference to FIG. 4.

The combined passage 40, which includes the restricting passage 381 and the pressure restoring passage 391, is directly formed in the front housing member 31.

The fourth embodiment has the same advantages as the advantages (1-1), (1-4), and (1-5) of the first embodiment.

A fifth embodiment will now be described with reference to FIGS. 5(a), 5(b), and 5(c). As shown in FIG. 5(a), an inlet 28 is formed in the circumferential wall of the rear housing member 12 and the circumferential wall 111 of the fixed scroll 11. A columnar passage forming body 66 is fitted in the inlet 28. A plurality of Combined passages 67 are formed in the passage forming body 66 and are arranged in parallel. As the movable scroll 20 orbits, refrigerant gas in the external refrigerant circuit, which is not shown, is introduced into the suction chamber 112 via the combined passages 67. The suction chamber 112 serves as a muffler, which forms part of the gas passage in the compressor 10. The combined passages 67 are located upstream of the suction chamber 112 in respect to the gas passage.

As shown in FIGS. 5(a), 5(b), and 5(c), each combined passage 67 has a pressure restoring passage 671, a restricting passage 672, and an introduction passage 673. The pressure restoring passage 671 is located downstream of the restricting passage 672. The restricting passage 672 is located downstream of the introduction passage 673. The diameter of the introduction passage 673 gradually decreases from the end close to the external refrigerant circuit (outside of the compressor 10) toward the restricting passage 672. A small diameter portion of the introduction passage 673 is connected to the restricting passage 672. As described above, the pulsation source is formed by the fixed scroll 11, the movable scroll 20, and the sealed spaces S0, S1. The pulsation of suction gas spreads from the pulsation source to the external refrigerant circuit via the suction chamber 112 and the combined passages 67. The suction chamber 112 and the restricting passages 672 reduce the pulsation of suction gas.

In each restricting passage 672, the pressure of refrigerant gas decreases as the flow rate of refrigerant gas increases. On the other hand, the pressure of refrigerant gas that has moved from the restricting passage 672 to the corresponding pressure restoring passage 671 increases as the flow rate of refrigerant gas decreases in the pressure restoring passage 671. That is, the pressure restoring passage 671 restores the pressure of refrigerant gas that has passed through the restricting passage 672. The pressure of refrigerant gas can be reduced in each restricting passage 672 by an amount that can be restored in the corresponding pressure restoring passage 671. Therefore, the cross-sectional area of each restricting passage 672 can be reduced to increase the pulsation reducing effect of the suction gas.

If a single combined passage is used at the inlet 28, the difference between the diameter of the restricting passage and the diameter of part of the gas passage upstream of the restricting passage becomes great, and the restricting effect of the restricting passage is increased. In this case, the length of the pressure restoring passage needs to be increased. However, when several combined passages 67 are arranged in parallel, the cross-sectional area of each restricting passage 672 can be reduced. This permits the length of each pressure restoring passage 671 to be shortened. Shortening the pressure restoring passages 671 shortens the combined passages 67. Shortening the combined passages 67 contributes to minimizing the size of the passage forming body 66. That is, the structure of arranging several combined passages 67 in parallel is advantageous in suppressing the size of the compressor 10 to which the passage forming body 66 is mounted.

The invention may be embodied in the following forms.

The present invention may be applied to compressors other than a scroll compressor and a piston type variable displacement compressor. For example, the present invention may be applied to a swash plate type compressor or a vane type compressor.

The present invention may be applied to devices that are equipped with a muffler as part of a gas passage in an exhaust system attached to a vehicle engine. In this case, the combined passage in which the restricting passage and the pressure restoring passage are connected in series is provided downstream of the muffler in respect to the gas passage. The pipe may be deformed by applying pressure on the outer circumferential surface of the pipe. The restricting passage and the pressure restoring passage may be formed in the pipe by such deformation.

The present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

Claims

1. A device having a pulsation reducing structure, the device comprising:

a gas passage;

a pulsation source connected to the gas passage, wherein pulsation of gas spreads from the pulsation source to the gas passage;

a muffler for reducing the pulsation, wherein the muffler is located in a part of the gas passage; and

a combined passage located in the gas passage, the combined passage is located upstream or downstream of the muffler with respect to a flowing direction of gas, the combined passage including a restricting passage and a pressure restoring passage, the restricting passage and the pressure restoring passage being connected in series, wherein the pressure restoring passage is located downstream of the restricting passage with respect to the flowing direction of gas, and wherein the muffler is located between the pulsation source and the combined passage in the gas passage.

2. The device according to claim 1, wherein the cross-sectional area of the pressure restoring passage is greater than the cross-sectional area of the restricting passage.

3. The device according to claim 1, wherein the cross-sectional area of the pressure restoring passage is gradually increased in the flowing direction of gas.

4. The device according to claim 1, wherein the pressure restoring passage is widened in the flowing direction of gas.

5. The device according to claim 4, wherein the widening angle of the pressure restoring passage is less than or equal to 20 degrees.

6. The device according to claim 1, wherein the combined passage is defined by a pipe located in the gas passage.

7. The device according to claim 6, further comprising a housing that defines the gas passage, wherein the pipe is formed separately from the housing.

8. The device according to claim 6, wherein at least part of the pipe is located in the muffler.

9. The device according to claim 8, wherein the pipe also functions as an oil separator, which separates oil from gas flowing through the gas passage.

10. The device according to claim 6, wherein the pipe includes an introduction passage, the introduction passage being located upstream of the restricting passage with respect to the flowing direction of gas, wherein the introduction passage is connected to the restricting passage in series, and the introduction passage is tapered toward the restricting passage.

11. The device according to claim 1, wherein an inlet of the restricting passage is widened in a direction opposite to the flowing direction of gas.

12. The device according to claim 1, wherein the combined passage is one of a plurality of combined passages, wherein the combined passages are arranged in parallel.

13. The device according to claim 1, wherein the device is a compressor for a vehicle air conditioner.

14. The device according to claim 1, wherein the device is provided in an exhaust system attached to a vehicle engine.

15. A passage forming body having a plurality of combined passages, the combined passages being arranged in parallel, wherein each combined passage includes a restricting passage and a pressure restoring passage, and wherein, in each combined passage, the restricting passage is combined with the pressure restoring passage in series.

16. A scroll compressor, comprising:

a compression mechanism including a movable scroll and a fixed scroll, the scrolls defining a compression chamber;

a discharge chamber for receiving gas discharged from the compression chamber;

a discharge gas passage for guiding discharge gas from the discharge chamber to the outside of the compressor;

a restricting passage located in the discharge gas passage; and

a pressure restoring passage located in the discharge gas passage, wherein the pressure restoring passage is connected to the restricting passage in series and located downstream of the restricting passage with respect to a flowing direction of gas.

17. The compressor according to claim 16, wherein the pressure restoring passage is widened in the flowing direction of gas, the widening angle being less than or equal to 20 degrees.

18. The compressor according to claim 16, further comprising:

a suction chamber for temporarily storing gas before the gas is drawn into the compression chamber; and

a suction gas passage for guiding gas into the suction chamber from the outside of the compressor,

wherein the suction gas passage includes a suction restricting passage and a suction pressure restoring passage that is located downstream of the suction restricting passage with respect to the flowing direction of gas.

19. A piston type compressor, comprising:

a compression chamber;

a discharge chamber into which gas compressed in the compression chamber is discharged; and

a discharge gas passage for guiding gas from the discharge chamber to the outside of the compressor, the discharge gas passage including a muffler, a restricting passage, and a pressure restoring passage, wherein the muffler reduces discharge pulsation of gas, which pulsation spreads from the discharge chamber through the discharge gas passage, the restricting passage is located downstream of the muffler with respect to a flowing direction of gas, and the pressure restoring passage is located downstream of the restricting passage.

20. The compressor according to claim 19, wherein the pressure restoring passage is widened in the flowing direction of gas, the widening angle being less than or equal to 20 degrees.