EP2330300A1

EP2330300A1 - Injection pipe

Info

Publication number: EP2330300A1
Application number: EP10741210A
Authority: EP
Inventors: Taichi Tateishi; Susumu Matsuda; Yoshiyuki Kimata; Yogo Takasu
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2009-02-13
Filing date: 2010-02-08
Publication date: 2011-06-08
Also published as: EP2330300A4; JP5683075B2; WO2010092933A1; JP2010185406A

Abstract

An injection pipe (17) that supplies a compressor (3) with a gas refrigerant subjected to gas/liquid separation by a receiver, which separates the reduced-pressure refrigerant into gas and liquid, or a gas refrigerant gasified by a heat exchanger, wherein a muffler (19) having an inside diameter larger than the inside diameter of the injection pipe (17) is provided at an end located at the compressor (3) side. This can reduce pulsation caused by a refrigerant flowing back from the compressor, which can reduce vibration and noise due to the pulsation, thereby preventing the pipe from being damaged by the vibration.

Description

{Technical Field}

The present invention relates to an injection pipe that constitutes a refrigerant circuit of an air conditioner.

{Background Art}

A known example of an injection pipe that constitutes a refrigerant circuit of an air conditioner is disclosed in Patent Literature 1.

{Citation List}

{Patent Literature}

{PTL 1}
Japanese Unexamined Patent Application, Publication No. Sho 60-128994

{Summary of Invention}

{Technical Problem}

However, the injection pipe disclosed in the above Patent Literature 1 has a risk of generating pulsation due to a refrigerant flowing back from a compressor when the (gas) injection level increases, which causes vibration and noise, and if the vibration is significant, damages the injection pipe.
The present invention is made in consideration of such circumstances, and it is an object thereof to provide an injection pipe in which pulsation caused by a refrigerant flowing back from a compressor can be reduced, so that vibration and noise due to the pulsation can be reduced, and thus damage to the pipe due to the vibration can be prevented.

{Solution to Problem}

The present invention adopts the following solutions to solve the problems described above.
An injection pipe according to a first aspect of the present invention is an injection pipe that supplies a compressor with a gas refrigerant subjected to gas/liquid separation by a receiver, which separates the reduced-pressure refrigerant into gas and liquid, or a gas refrigerant gasified by a heat exchanger, wherein a muffler having an inside diameter larger than the inside diameter of the injection pipe is provided at an end located at the compressor side.
With the injection pipe according to the first aspect of the present invention, since pulsation caused by a refrigerant flowing back from the compressor is reduced (absorbed) by the muffler, vibration and noise due to the pulsation can be reduced, and thus, damage to the pipe due to the vibration can be prevented.
It is more preferable that the injection pipe be configured such that the muffler has an oil separating function, and lubricant oil separated by the muffler is returned to an oil sump of the compressor through an oil return pipe.
With such an injection pipe, since lubricant oil in the refrigerant flowing back from the compressor is separated by the muffler, and the separated lubricant oil is returned to the compressor through the oil return pipe, the oil circulation rate (OCR: Or%) of lubricant oil circulated to a refrigerating cycle [the ratio of the mass flow rate of the lubricant oil to the total mass flow rate (refrigerant flow rate + lubricant-oil flow rate)] can be reduced.
An air conditioner according to a second aspect of the present invention is equipped with an injection pipe in which vibration and noise due to pulsation can be reduced, and thus damage to the pipe due to the vibration can be prevented.
With the air conditioner according to the second aspect of the present invention, since the pulsation caused by the refrigerant flowing back from the compressor is reduced (absorbed) by the muffler provided at the injection pipe, low vibration and low noise can be achieved even if the injection level is considerably high.

{Advantageous Effects of Invention}

The injection pipe according to the present invention offers the advantages of reducing pulsation caused by a refrigerant flowing back from the compressor, which can reduce vibration and noise due to the pulsation, thereby preventing the pipe from being damaged by the vibration.

{Brief Description of Drawings}

{Fig. 1} Fig. 1 is a schematic diagram showing the overall configuration of an air conditioner equipped with an injection pipe according to the present invention.
{Fig. 2} Fig. 2 is a side view of an air conditioner compressor to which an injection pipe according to a first embodiment of the present invention is connected.
{Fig. 3} Fig. 3 is a graph showing experimental results obtained by operating an air conditioner equipped with the injection pipe according to the first embodiment.
{Fig. 4} Fig. 4 is a graph showing the relationship between the inside diameter of a muffler provided at the injection pipe according to the present invention and the magnitude of pulsation caused by a refrigerant flowing back from the air conditioner compressor.
{Fig. 5} Fig. 5 is a side view of an air conditioner compressor to which an injection pipe according to a second embodiment of the present invention is connected.
{Fig. 6} Fig. 6 is a schematic diagram showing the overall configuration of another air conditioner equipped with the injection pipe according to the present invention.

{Description of Embodiments}

A first embodiment of an injection pipe according to the present invention will be described below with reference to Figs. 1 to 4.
Fig. 1 is a schematic diagram showing the overall configuration of an air conditioner equipped with an injection pipe according to the present invention; Fig. 2 is a side view of an air conditioner compressor to which the injection pipe according to this embodiment is connected; Fig. 3 is a graph showing experimental results obtained by operating an air conditioner equipped with the injection pipe according to this embodiment; Fig. 4 is a graph showing the relationship between the inside diameter of a muffler provided at the injection pipe according to the present invention and the magnitude of pulsation caused by a refrigerant flowing back from the air conditioner compressor.
As shown in Fig. 1, the air conditioner 1 includes an air conditioner compressor (for example, scroll compressor) 3 that compresses a refrigerant, a condenser (radiator) 5 that radiates the heat of the compressed refrigerant, a first expansion valve (high-pressure-side pressure reducing portion) 7 that reduces the pressure of the refrigerant whose heat is radiated, a receiver 9 that separates the reduced-pressure refrigerant into gas and liquid, a second expansion valve (low-pressure-side pressure reducing portion) 11 that further reduces the pressure of the liquid refrigerant, and an evaporator (heat sink) 13 in which heat is absorbed by the reduced-pressure liquid refrigerant.
Furthermore, an injection pipe 17 that supplies the air conditioner compressor 3 with the gas refrigerant subjected to gas/liquid separation by the receiver 9 is disposed between the receiver 9 and the air conditioner compressor (air-conditioning compressor) 3.
As shown in Fig. 2, the injection pipe 17 according to this embodiment is provided with a muffler 19 at an intermediate point (in this embodiment, an end close to an injection port (not shown) formed at the air conditioner compressor 3).
The muffler 19 is a straight-pipe-like member having an inside diameter, for example, double the inside diameter of the injection pipe 17 and a length, for example, ten times the inside diameter of the injection pipe 17 and is disposed along a horizontal direction.
The muffler 19 is disposed at a position where a length L from its gas outlet to the injection port is smaller than 2 × T × a and is minimized in consideration of relationships with devices and pipes disposed therearound and the piping of the injection pipe 17 and so on, where T is a closing time (time corresponding to about half of the frequency (which varies depending on the conditions); for example, assuming that the rotational speed of the air conditioner compressor 3 is 120 Hz, and the injection port is closed for a time corresponding to half of the frequency, T is 1/120/2 (sec)), and a is the speed of sound.
With the injection pipe 17 according to this embodiment, since the pulsation caused by the refrigerant flowing back from the air conditioner compressor 3 is reduced (absorbed) by the muffler 19, vibration and noise due to the pulsation can be reduced, and thus, damage to the pipe due to the vibration can be prevented.
Furthermore, with the air conditioner 1 equipped with the injection pipe 17 according to this embodiment, since the pulsation caused by the refrigerant flowing back from the air conditioner compressor 3 is reduced (absorbed) by the muffler 19 provided (mounted) at the injection pipe 17, low vibration and low noise can be achieved even if the injection level is considerably high.
Fig. 3 is a graph showing experimental results obtained by operating the air conditioner 1 equipped with the injection pipe 17 according to this embodiment, in which the horizontal axis indicates injection flow rate [ratio], and the vertical axis indicates pulsation value [ratio].
As shown in Fig. 3, with the air conditioner 1 equipped with the injection pipe 17 according to this embodiment, the pulsation is remarkably reduced compared with an air conditioner that is not equipped with the injection pipe 17 according to this embodiment, which shows effective experimental results that support the above operational advantages due to the injection pipe 17 according to this embodiment.
Fig. 4 is a graph showing the relationship between the inside diameter of the muffler 19 and the magnitude of the pulsation caused by a refrigerant flowing back from the air conditioner compressor 3, in which the horizontal axis indicates pipe diameter [ratio], that is, how many times larger is the inside diameter of the muffler 19 than the inside diameter of the injection pipe 17, and the vertical axis indicates pulsation value [ratio].
Fig. 4 shows that the pulsation decreases as the inside diameter of the muffler 19 increases.
A second embodiment of the injection pipe according to the present invention will be described with reference to Fig. 5. Fig. 5 is a side view of an air conditioner compressor to which the injection pipe according to this embodiment is connected.
An injection pipe 21 according to this embodiment differs from that of the foregoing first embodiment in that a muffler 23 is provided instead of the muffler 19. Since the other components are the same as those of the foregoing first embodiment, descriptions of those components are omitted here.
As shown in Fig. 5, the injection pipe 21 according to this embodiment is provided with the muffler 23 having an oil separating function at an intermediate portion (in this embodiment, an end close to an injection port (not shown) formed at the air conditioner compressor 3).
The muffler 23 has the function of separating lubricant oil from the refrigerant using, for example, centrifugal force, and has a shape as shown in Fig. 5.
The muffler 23 is disposed at a position where a length L from its gas outlet to the injection port is smaller than 2 × T × a and is minimized in consideration of relationships with devices and pipes disposed therearound and the piping of the injection pipe 21 and so on, where T is a closing time (time corresponding to about half of the frequency (which varies depending on the conditions); for example, assuming that the rotational speed of the air conditioner compressor 3 is 120 Hz, and the injection port is closed for a time corresponding to half of the frequency, T is 1/120/2 (sec)), and a is the speed of sound.
Reference sign 25 in Fig. 5 denotes an oil return pipe for returning the lubricant oil separated by the muffler 23 to the bottom (lubricant oil sump) of the air conditioner compressor 3.
With the injection pipe 21 according to this embodiment, since the pulsation caused by the refrigerant flowing back from the air conditioner compressor 3 is reduced (absorbed) by the muffler 23, vibration and noise due to the pulsation can be reduced, and thus, damage to the pipe due to the vibration can be prevented.
Furthermore, with the air conditioner 1 equipped with the injection pipe 21 according to this embodiment, since lubricant oil in the refrigerant flowing back from the air conditioner compressor 3 is separated by the muffler 23, and the separated lubricant oil is returned to the air conditioner compressor 3 through the oil return pipe 25, the oil circulation rate (OCR: OC%) of lubricant oil circulated to a refrigerating cycle [the ratio of the mass flow rate of the lubricant oil to the total mass flow rate (refrigerant flow rate + lubricant-oil flow rate)] can be reduced, and thus, the system efficiency can be enhanced, and lack of lubricant oil in the air conditioner compressor 3 can be prevented.
Furthermore, with the air conditioner 1 equipped with the injection pipe 21 according to this embodiment, since the pulsation caused by the refrigerant flowing back from the air conditioner compressor 3 is reduced (absorbed) by the muffler 23 provided (mounted) at the injection pipe 21, low vibration and low noise can be achieved even if the injection level is considerably high.
The present invention is not limited to the embodiments described above, and various modifications and changes may be made as appropriate without departing from the technical spirit of the present invention.
For example, the muffler 19 described in the first embodiment may be an enlarged-diameter intermediate portion of the injection pipe 17.
The injection pipes 17 and 21 according to the present invention are applied not only to the air conditioner 1 having the configuration shown in Fig. 1; they may be applied also to, for example, an air conditioner 31 having the configuration shown in Fig. 6.
In Fig. 6, reference sign 32 in the drawing denotes a pressure reducing valve (third expansion valve), and reference sign 33 denotes a heat exchanger. The pipe connected to the outlet of the condenser 5 is split into two at the upstream side of the heat exchanger 33, of which one pipe is connected to the second expansion valve 11 via the heat exchanger 33, and the other pipe is connected to the injection pipe 17 or 21 via the heat exchanger 33. The pressure reducing valve 32 is connected to the other pipe located at the upstream side of the heat exchanger 33, through which the reduced-pressure refrigerant is introduced into the heat exchanger 33. In the heat exchanger 33, the refrigerant passing through the other pipe is increased in temperature (heated) to be gasified by the refrigerant passing through one pipe, and the gasified refrigerant is introduced to the compressor 3 via the injection pipe 17 or 21.

{Reference Signs List}

1: air conditioner
3: air conditioner compressor (compressor)
9: receiver
17: injection pipe
19: muffler
21: injection pipe
23: muffler,
25: oil return pipe
31: air conditioner
33: heat exchanger

Claims

An injection pipe that supplies a compressor with a gas refrigerant subjected to gas/liquid separation by a receiver, which separates the reduced-pressure refrigerant into gas and liquid, or a gas refrigerant gasified by a heat exchanger, wherein
a muffler having an inside diameter larger than the inside diameter of the injection pipe is provided at an end located at the compressor side.
The injection pipe according to Claim 1, wherein the muffler has an oil separating function, and lubricant oil separated by the muffler is returned to an oil sump of the compressor through an oil return pipe.
An air conditioner comprising the injection pipe according to Claim 1 or 2.