JP7198116B2

JP7198116B2 - Multi-stage compressor

Info

Publication number: JP7198116B2
Application number: JP2019037458A
Authority: JP
Inventors: 豪土屋; 紘太郎千葉; 利明矢部; 雅之笠原; 航平酒井; 雄二伊藤
Original assignee: Hitachi Industrial Equipment Systems Co Ltd
Current assignee: Hitachi Industrial Equipment Systems Co Ltd
Priority date: 2019-03-01
Filing date: 2019-03-01
Publication date: 2022-12-28
Anticipated expiration: 2039-03-01
Also published as: JP2020139487A

Description

本発明は、複数の圧縮機本体を備えた多段圧縮機に関する。 The present invention relates to a multi-stage compressor having multiple compressor bodies.

近年、圧縮機の省エネ化が強く求められており、高効率や大風量であることが益々重要になっている。圧縮機の多段化は、そのための手法の１つであり、例えば、特許文献１は、二段スクリュー圧縮機を開示する。 In recent years, there is a strong demand for energy-saving compressors, and high efficiency and large air volume are becoming more and more important. A multi-stage compressor is one of the methods for achieving this. For example, Patent Literature 1 discloses a two-stage screw compressor.

多段圧縮機は、前段圧縮機本体と、前段圧縮機本体で圧縮された気体を更に圧縮する後段圧縮機本体と、前段圧縮機本体の吐出側と後段圧縮機本体の吸入側の間で接続された中間流路とを備える。 The multistage compressor is connected between a front compressor body, a rear compressor body that further compresses the gas compressed by the front compressor body, a discharge side of the front compressor body, and a suction side of the rear compressor body. and an intermediate flow path.

特開２０１７－１６６４０１号公報JP 2017-166401 A

中間流路の圧力（以降、中間圧力という）の設定値は、多段圧縮機の圧力比（詳細には、最終段圧縮機本体の吐出側圧力と初段圧縮機本体の吸入側圧力との比）の設定値に応じて決める。構造上の各段圧縮機本体の容積比（詳細には、吸入完了時の作動室の容積と吐出開始時の作動室の容積との比）は、多段圧縮機の圧力比の設定値と中間圧力の設定値に基づいて設計する。 The set value of the pressure in the intermediate flow path (hereinafter referred to as the intermediate pressure) is the pressure ratio of the multi-stage compressor (more specifically, the ratio of the pressure on the discharge side of the main body of the final stage compressor and the pressure on the suction side of the main body of the first stage compressor). Determined according to the set value of . Structurally, the volume ratio of the main body of each stage compressor (more specifically, the ratio of the volume of the working chamber at the completion of suction to the volume of the working chamber at the start of discharge) is between the set value of the pressure ratio of the multi-stage compressor and the Design based on pressure setting.

ところで、多段圧縮機の運転条件（詳細には、例えば最終段圧縮機本体の吐出側圧力の制御値）によって多段圧縮機の圧力比の運転値が変化し、これに伴って中間圧力の運転値が変化する。また、各段圧縮機本体の圧力差（詳細には、吐出側圧力と吸入側圧力との差）が変化し、これに伴って各段圧縮機本体の体積効率が変化し、その影響も受けて中間圧力の運転値が変化する。 By the way, the operating value of the pressure ratio of the multi-stage compressor changes depending on the operating conditions of the multi-stage compressor (more specifically, for example, the control value of the discharge side pressure of the main body of the final stage compressor), and accordingly the operating value of the intermediate pressure changes. In addition, the pressure difference between the main bodies of each stage compressor (more specifically, the difference between the pressure on the discharge side and the pressure on the suction side) changes, and accordingly the volumetric efficiency of the main body of each stage compressor changes. , the operating value of the intermediate pressure changes.

中間圧力の運転値が設定値より高ければ、前段圧縮機本体の圧縮行程の作動室の圧力が中間圧力の運転値より低くなり、圧縮不足な状態となる。そのため、中間圧力の設定値が比較的高くなるように、各段圧縮機本体の容積比を設計することが好ましい。しかし、中間圧力の設定値が比較的高くなるように設計した場合、中間圧力の運転値が設定値より低くなりやすい。中間圧力の運転値が設定値より低ければ、前段圧縮機本体の圧縮行程の作動室の圧力が中間圧力の運転値より高くなり、圧縮過剰な状態となる。すなわち、エネルギー損失が発生し、効率が低下する。 If the operating value of the intermediate pressure is higher than the set value, the pressure in the working chamber during the compression stroke of the pre-compressor main body becomes lower than the operating value of the intermediate pressure, resulting in insufficient compression. Therefore, it is preferable to design the volume ratio of each stage compressor main body so that the set value of the intermediate pressure is relatively high. However, when the intermediate pressure is designed to have a relatively high set value, the operating value of the intermediate pressure tends to be lower than the set value. If the operating value of the intermediate pressure is lower than the set value, the pressure in the working chamber during the compression stroke of the pre-compressor body becomes higher than the operating value of the intermediate pressure, resulting in excessive compression. That is, energy loss occurs and efficiency decreases.

本発明は、上記事柄に鑑みてなされたものであり、中間圧力の変化に応じて前段圧縮機本体の圧縮行程の作動室の圧力を調整して、効率を向上させることを課題の一つとするものである。 SUMMARY OF THE INVENTION It is an object of the present invention to improve efficiency by adjusting the pressure in the working chamber in the compression stroke of the main body of the pre-compressor in accordance with the change in the intermediate pressure. It is.

上記課題を解決するために、特許請求の範囲に記載の構成を適用する。本発明は、上記課題を解決するための手段を複数含んでいるが、その一例を挙げるならば、前段圧縮機本体と、前記前段圧縮機本体で圧縮された気体を更に圧縮する後段圧縮機本体と、前記前段圧縮機本体の吐出側と前記後段圧縮機本体の吸入側の間で接続された中間流路と、前記後段圧縮機本体の吐出側に接続された吐出流路と、を備えた多段圧縮機において、前記前段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と前記中間流路を連通する前段弁孔と、前記前段弁孔に配置され、前記前段圧縮機本体の前記圧縮行程の作動室の圧力と前記中間流路の圧力との差圧によって作動する前段リリース弁と、前記後段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と前記吐出流路の間で接続された後段弁孔と、前記後段弁孔に配置され、前記後段圧縮機本体の前記圧縮行程の作動室の圧力と前記吐出流路の圧力との差圧によって作動する後段リリース弁とを備え、前記前段リリース弁は、前記前段圧縮機本体の前記圧縮行程の作動室の圧力が前記中間流路の圧力より低い場合に前記前段弁孔を遮断状態とし、前記前段圧縮機本体の前記圧縮行程の作動室の圧力が前記中間流路の圧力より高い場合に前記前段弁孔を連通状態とし、前記後段リリース弁は、前記後段圧縮機本体の前記圧縮行程の作動室の圧力が前記吐出流路の圧力より低い場合に前記後段弁孔を遮断状態とし、前記後段圧縮機本体の前記圧縮行程の作動室の圧力が前記吐出流路の圧力より高い場合に前記後段弁孔を連通状態とする。 In order to solve the above problems, the configurations described in the claims are applied. The present invention includes a plurality of means for solving the above-mentioned problems, and to give an example, a front compressor main body and a rear compressor main body for further compressing the gas compressed by the front compressor main body an intermediate flow path connected between the discharge side of the front-stage compressor body and the suction side of the rear-stage compressor body; and a discharge flow path connected to the discharge side of the rear-stage compressor body . In the multi-stage compressor, a front stage valve hole that communicates the intermediate passage with a working chamber for a compression stroke different from a working chamber for a discharge stroke of the front stage compressor main body; a pressure difference between the pressure in the working chamber in the compression stroke and the pressure in the intermediate flow path ; a post-stage valve hole connected between the flow paths, and a post-stage arranged in the post-stage valve hole and operated by a pressure difference between a pressure in the working chamber during the compression stroke of the post-compressor main body and a pressure in the discharge flow path. a release valve , wherein the pre-stage release valve blocks the pre-stage valve hole when the pressure in the working chamber in the compression stroke of the pre-compressor main body is lower than the pressure in the intermediate flow path, and the pre-stage compressor When the pressure in the compression stroke working chamber of the main body is higher than the pressure in the intermediate flow path, the front stage valve hole is brought into communication, and the rear release valve opens the pressure in the compression stroke working chamber of the rear compressor body. The latter valve hole is closed when the pressure is lower than the pressure in the discharge passage, and the latter valve hole is closed when the pressure in the working chamber of the compression stroke of the latter compressor body is higher than the pressure in the discharge passage. are in communication.

本発明によれば、中間圧力の変化に応じて前段圧縮機本体の圧縮行程の作動室の圧力を調整して、効率を向上させることができる。 According to the present invention, efficiency can be improved by adjusting the pressure in the working chamber in the compression stroke of the main body of the pre-compressor according to the change in the intermediate pressure.

なお、上記以外の課題、構成及び効果は、以下の説明により明らかにされる。 Problems, configurations, and effects other than those described above will be clarified by the following description.

本発明の第１の実施形態における二段スクリュー圧縮機の概略構造を表す鉛直断面図である。1 is a vertical sectional view showing a schematic structure of a two-stage screw compressor according to a first embodiment of the present invention; FIG. 本発明の第１の実施形態における前段圧縮機本体の構造を表す水平断面図である。FIG. 2 is a horizontal cross-sectional view showing the structure of the main body of the pre-compressor in the first embodiment of the present invention; 本発明の第１の実施形態における前段圧縮機本体の構造を表す径方向断面図である。FIG. 3 is a radial cross-sectional view showing the structure of the main body of the pre-compressor in the first embodiment of the present invention; 本発明の第１の変形例における前段圧縮機本体の構造を表す水平断面図である。It is a horizontal sectional view showing the structure of the front stage compressor main body in the 1st modification of this invention. 本発明の第２の実施形態における二段スクリュー圧縮機の概略構造を表す鉛直断面図である。FIG. 5 is a vertical cross-sectional view showing a schematic structure of a two-stage screw compressor according to a second embodiment of the present invention; 本発明の第２の変形例における二段スクロール圧縮機の概略構造を表す鉛直断面図である。FIG. 5 is a vertical cross-sectional view showing a schematic structure of a two-stage scroll compressor in a second modified example of the present invention; 本発明の第３の変形例における二段スクロール圧縮機の概略構造を表す鉛直断面図である。FIG. 5 is a vertical cross-sectional view showing a schematic structure of a two-stage scroll compressor in a third modified example of the invention; 本発明の第４の変形例におけるリリース弁の構造を表す断面図である。FIG. 11 is a cross-sectional view showing the structure of a release valve in a fourth modified example of the invention;

本発明の適用対象として二段スクリュー圧縮機を例にとり、本発明の第１の実施形態を、図１～図３を用いて説明する。 Taking a two-stage screw compressor as an example to which the present invention is applied, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

図１は、本実施形態における二段スクリュー圧縮機の概略構造を表す鉛直断面図である。図２は、本実施形態における前段圧縮機本体の構造を表す水平断面図である。図３は、本実施形態における前段圧縮機本体の構造を表す径方向断面図である。なお、図２においては、便宜上、前段リリース弁のリテーナの図示を省略する。 FIG. 1 is a vertical sectional view showing a schematic structure of a two-stage screw compressor in this embodiment. FIG. 2 is a horizontal sectional view showing the structure of the main body of the pre-compressor in this embodiment. FIG. 3 is a radial cross-sectional view showing the structure of the main body of the pre-compressor in this embodiment. In addition, in FIG. 2, for the sake of convenience, illustration of the retainer of the pre-stage release valve is omitted.

本実施形態の二段スクリュー圧縮機は、前段圧縮機本体１と、前段圧縮機本体１で圧縮された気体（詳細には、空気又は冷媒等）を更に圧縮する後段圧縮機本体２と、前段圧縮機本体１の吐出側と後段圧縮機本体２の吸入側の間で接続された中間流路３と、後段圧縮機本体２の吐出側に接続された吐出流路４とを備える。なお、図示しないものの、中間流路３にはインタークーラが設けられ、吐出流路４にはアフタークーラが設けられている。 The two-stage screw compressor of this embodiment includes a front compressor main body 1, a rear compressor main body 2 for further compressing gas (specifically, air or refrigerant, etc.) compressed by the front compressor main body 1, An intermediate flow path 3 connected between the discharge side of the compressor main body 1 and the suction side of the post-compressor main body 2 and a discharge flow path 4 connected to the discharge side of the post-compressor main body 2 are provided. Although not shown, the intermediate flow path 3 is provided with an intercooler, and the discharge flow path 4 is provided with an aftercooler.

前段圧縮機本体１は、回転軸が平行で互いに噛み合う雄ロータ５Ａ及び雌ロータ６Ａ（スクリューロータ）と、雄ロータ５Ａ及び雌ロータ６Ａを収納して、それらの歯溝に雄ロータ側作動室及び雌ロータ側作動室を形成するケーシング７Ａとを備える。 The pre-compressor main body 1 accommodates a male rotor 5A and a female rotor 6A (screw rotors) having parallel rotation axes and meshing with each other, and a male rotor 5A and a female rotor 6A. and a casing 7A forming a female rotor side working chamber.

雄ロータ５Ａは、吸入側軸受８Ａ及び吐出側軸受９Ａで回転可能に支持され、雌ロータ６Ａは、吸入側軸受８Ｂ及び吐出側軸受９Ｂで回転可能に支持されている。雄ロータ５Ａ及び雌ロータ６Ａのうちの一方は、第１モータ（図示せず）によって回転し、他方は、雄ロータ５Ａと雌ロータ６Ａの噛み合いによって回転する。但し、ギアを用いて、雄ロータ５Ａと雌ロータ６Ａを同期回転させてもよい。 The male rotor 5A is rotatably supported by a suction side bearing 8A and a discharge side bearing 9A, and the female rotor 6A is rotatably supported by a suction side bearing 8B and a discharge side bearing 9B. One of the male rotor 5A and the female rotor 6A is rotated by a first motor (not shown), and the other is rotated by the meshing of the male rotor 5A and the female rotor 6A. However, gears may be used to synchronously rotate the male rotor 5A and the female rotor 6A.

雄ロータ５Ａ及び雌ロータ６Ａの回転に伴い、雄ロータ側作動室及び雌ロータ側作動室は、軸方向の一方側（図１及び図２の左側）から他方側（図１及び図２の右側）へ移動しつつ、それらの容積が変化する。これにより、吸入行程、圧縮行程、吐出行程を順次行うようになっている。詳しく説明すると、吸入行程の雄ロータ側作動室Ｘ１及び雌ロータ側作動室Ｙ１は、それらの容積が増加して、吸入口１０Ａから気体を吸入する。圧縮行程の雄ロータ側作動室Ｘ２及び雌ロータ側作動室Ｙ２は、それらの容積が縮小して、気体を圧縮する。吐出行程の雄ロータ側作動室Ｘ３及び雌ロータ側作動室Ｙ３は、吐出口１１Ａから圧縮気体を吐出する。 As the male rotor 5A and the female rotor 6A rotate, the male rotor side working chamber and the female rotor side working chamber move from one axial side (left side in FIGS. 1 and 2) to the other side (right side in FIGS. 1 and 2). ), their volumes change. As a result, a suction stroke, a compression stroke, and a discharge stroke are sequentially performed. More specifically, in the suction stroke, the male rotor side working chamber X1 and the female rotor side working chamber Y1 increase in volume and suck gas from the suction port 10A. The volumes of the male rotor side working chamber X2 and the female rotor side working chamber Y2 in the compression stroke are reduced to compress the gas. The male rotor side working chamber X3 and the female rotor side working chamber Y3 in the discharge stroke discharge the compressed gas from the discharge port 11A.

後段圧縮機本体２は、回転軸が平行で互いに噛み合う雄ロータ５Ｂ及び雌ロータ６Ｂ（但し、５Ｂのみ図示）と、雄ロータ５Ｂ及び雌ロータ６Ｂを収納して、それらの歯溝に雄ロータ側作動室及び雌ロータ側作動室を形成するケーシング７Ｂとを備える。 The post-compressor main body 2 accommodates a male rotor 5B and a female rotor 6B (only 5B is shown) which are meshed with each other and whose rotating shafts are parallel, and the male rotor 5B and the female rotor 6B. It has a casing 7B that forms a working chamber and a female rotor side working chamber.

雄ロータ５Ｂは、吸入側軸受及び吐出側軸受（図示せず）で回転可能に支持され、雌ロータ６Ｂは、吸入側軸受及び吐出側軸受（図示せず）で回転可能に支持されている。雄ロータ５Ｂ及び雌ロータ６Ｂのうちの一方は、第２モータ（図示せず）によって回転し、他方は、雄ロータ５Ｂと雌ロータ６Ｂの噛み合いによって回転する。但し、ギアを用いて、雄ロータ５Ｂと雌ロータ６Ｂを同期回転させてもよい。 The male rotor 5B is rotatably supported by a suction side bearing and a discharge side bearing (not shown), and the female rotor 6B is rotatably supported by a suction side bearing and a discharge side bearing (not shown). One of the male rotor 5B and the female rotor 6B is rotated by a second motor (not shown), and the other is rotated by the meshing of the male rotor 5B and the female rotor 6B. However, gears may be used to synchronously rotate the male rotor 5B and the female rotor 6B.

雄ロータ５Ｂ及び雌ロータ６Ｂの回転に伴い、雄ロータ側作動室及び雌ロータ側作動室は、軸方向の一方側（図１の左側）から他方側（図１の右側）へ移動しつつ、その容積が変化する。これにより、吸入行程、圧縮行程、吐出行程を順次行うようになっている。詳しく説明すると、吸入行程の雄ロータ側作動室Ｘ４及び雌ロータ側作動室（図示せず）は、それらの容積が増加して、吸入口１０Ｂから気体を吸入する。圧縮行程の雄ロータ側作動室Ｘ５及び雌ロータ側作動室（図示せず）は、それらの容積が縮小して、気体を圧縮する。吐出行程の雄ロータ側作動室Ｘ６及び雌ロータ側作動室（図示せず）は、吐出口１１Ｂから圧縮気体を吐出する。 As the male rotor 5B and the female rotor 6B rotate, the male rotor side working chamber and the female rotor side working chamber move from one side (left side in FIG. 1) to the other side (right side in FIG. 1) in the axial direction. Its volume changes. As a result, a suction stroke, a compression stroke, and a discharge stroke are sequentially performed. More specifically, the male rotor side working chamber X4 and the female rotor side working chamber (not shown) in the suction stroke increase in volume and suck gas from the suction port 10B. The volumes of the male rotor side working chamber X5 and the female rotor side working chamber (not shown) in the compression stroke are reduced to compress the gas. The male rotor side working chamber X6 and the female rotor side working chamber (not shown) in the discharge stroke discharge compressed gas from the discharge port 11B.

ここで、本実施形態の特徴の一つとして、二段スクリュー圧縮機の圧力比（詳細には、後段圧縮機本体２の吐出側圧力と前段圧縮機本体１の吸入側圧力との比）の運転値の変化に伴う中間流路３の圧力（以降、中間圧力という）の運転値の変化を考慮するため、中間圧力の設定値が比較的高くなるように、前段圧縮機本体１の容積比が設定されている。これにより、前段圧縮機本体１の圧縮不足を回避するようになっている。以下、その詳細を説明する。 Here, as one of the features of the present embodiment, the pressure ratio of the two-stage screw compressor (more specifically, the ratio of the pressure on the discharge side of the main body 2 of the post-stage compressor and the pressure on the side of the suction side of the main body 1 of the pre-compressor) is In order to consider changes in the operating value of the pressure in the intermediate flow path 3 (hereinafter referred to as intermediate pressure) accompanying changes in the operating value, the volume ratio of the pre-compressor main body 1 is adjusted so that the set value of the intermediate pressure is relatively high. is set. As a result, insufficient compression of the pre-compressor main body 1 is avoided. The details are described below.

中間流路３の圧力損失や気体漏れが無いと仮定し、後段圧縮機本体２の吸気温度が前段圧縮機本体１の吸気温度と同じであると仮定した場合に、動力が最小になるための前段圧縮機本体１の圧力比Ｐｉ／Ｐｓ１は、下記の式（１）で与えられる。Ｐｓ１は前段圧縮機本体１の吸入側圧力、Ｐｉは中間圧力、Ｐｄ２は後段圧縮機本体２の吐出側圧力である。 Assuming that there is no pressure loss or gas leakage in the intermediate passage 3, and that the intake air temperature of the post-compressor main body 2 is the same as the intake air temperature of the pre-compressor main body 1, the power is minimized. The pressure ratio Pi/Ps1 of the pre-compressor body 1 is given by the following equation (1). Ps1 is the pressure on the suction side of the main body 1 of the pre-compressor, Pi is the intermediate pressure, and Pd2 is the pressure on the side of the discharge of the main body 2 of the post-compressor.

しかしながら、実際には、中間流路３での冷却不足により、後段圧縮機本体２の吸気温度が前段圧縮機本体１の吸気温度と同じにならない。また、二段スクリュー圧縮機の圧力比の運転値が変化すると、各段圧縮機本体の圧力差（詳細には、吐出側圧力と吸入側圧力との差）も変化し、これに伴って各段圧縮機本体の体積効率が変化する。そして、下記の式（２）で示すように、前段圧縮機本体１の圧力比Ｐｉ／Ｐｓ１は、後段圧縮機本体２の行程容積Ｖｔｈ２と前段圧縮機本体１の行程容積Ｖｔｈ１との比、後段圧縮機本体２の回転数Ｎ２と前段圧縮機本体１の回転数Ｎ１との比、後段圧縮機本体２の体積効率ηｖ２と前段圧縮機本体１の体積効率ηｖ１との比、及び後段圧縮機本体２の吸入側温度Ｔｓ２と前段圧縮機本体１の吸入側温度Ｔｓ１との比で決まる。すなわち、実際の圧力比Ｐｉ／Ｐｓ１は、式（１）を用いて算出された理想値より高くなる。 However, in practice, due to insufficient cooling in the intermediate passage 3, the intake air temperature of the post-compressor main body 2 does not become the same as the intake air temperature of the pre-compressor main body 1. In addition, when the operating value of the pressure ratio of the two-stage screw compressor changes, the pressure difference in the main body of each stage compressor (more specifically, the difference between the discharge side pressure and the suction side pressure) also changes. The volumetric efficiency of the stage compressor body changes. Then, as shown by the following equation (2), the pressure ratio Pi/Ps1 of the front compressor body 1 is the ratio of the stroke volume Vth2 of the rear compressor body 2 and the stroke volume Vth1 of the front compressor body 1, The ratio between the rotation speed N2 of the compressor main body 2 and the rotation speed N1 of the pre-compressor main body 1, the ratio between the volumetric efficiency ηv2 of the post-compressor main body 2 and the volumetric efficiency ηv1 of the pre-compressor main body 1, and the post-compressor main body 2 and the suction side temperature Ts1 of the main body 1 of the pre-compressor. That is, the actual pressure ratio Pi/Ps1 is higher than the ideal value calculated using equation (1).

例えば二段スクリュー圧縮機の圧力比の運転値が８～９の範囲で変化する場合を想定する。式（１）を用いれば、二段スクリュー圧縮機の圧力比Ｐｄ２／Ｐｓ１＝９であるとき、前段圧縮機本体１の圧力比Ｐｉ／Ｐｓ１＝３である（すなわち、前段圧縮機本体１の吸入側圧力Ｐｓ１＝０．１ＭＰａであれば、中間圧力Ｐｉ＝０．３ＭＰａである）。そして、圧力比Ｐｉ／Ｐｓ１＝３（理想値）に対応する前段圧縮機本体１の容積比＝２．２であるものの、実際の圧力比Ｐｉ／Ｐｓ１が理想値より高いため、前段圧縮機本体１の容積比＝２．３となるように設定する。これにより、二段スクリュー圧縮機の圧力比の運転値の変化に伴って中間圧力の運転値が変化しても、前段圧縮機本体１の圧縮行程の作動室の圧力が中間圧力の運転値より高くならない。したがって、圧縮不足な状態とならない。 For example, assume that the operating value of the pressure ratio of a two-stage screw compressor varies in the range of 8-9. Using formula (1), when the pressure ratio of the two-stage screw compressor is Pd2/Ps1=9, the pressure ratio of the pre-compressor main body 1 is Pi/Ps1=3 (that is, the suction of the pre-compressor main body 1 If the side pressure Ps1=0.1 MPa, then the intermediate pressure Pi=0.3 MPa). Although the volume ratio of the pre-compressor main body 1 corresponding to the pressure ratio Pi/Ps1=3 (ideal value) is 2.2, since the actual pressure ratio Pi/Ps1 is higher than the ideal value, the pre-compressor main body The volume ratio of 1 is set to 2.3. As a result, even if the operating value of the intermediate pressure changes with changes in the operating value of the pressure ratio of the two-stage screw compressor, the pressure in the working chamber in the compression stroke of the pre-compressor main body 1 is lower than the operating value of the intermediate pressure. not high. Therefore, under-compression does not occur.

また、例えば二段スクリュー圧縮機の圧力比の運転値が８～１４の範囲で変化する場合を想定する。式（１）を用いれば、二段スクリュー圧縮機の圧力比Ｐｄ２／Ｐｓ１＝１４であるとき、前段圧縮機本体１の圧力比Ｐｉ／Ｐｓ１＝３．７４である（すなわち、前段圧縮機本体１の吸入側圧力Ｐｓ１＝０．１ＭＰａであれば、中間圧力Ｐｉ＝０．３７４ＭＰａである）。そして、圧力比Ｐｉ／Ｐｓ１＝３．７４（理想値）に対応する前段圧縮機本体１の容積比＝２．６であるものの、実際の圧力比Ｐｉ／Ｐｓ１が理想値より高いため、前段圧縮機本体１の容積比＝２．８となるように設定する。これにより、二段スクリュー圧縮機の圧力比の運転値の変化に伴って中間圧力の運転値が変化しても、前段圧縮機本体１の圧縮行程の作動室の圧力が中間圧力の運転値より高くならない。したがって、圧縮不足な状態とならない。前述した考察によれば、前段圧縮機本体１の容積比は、２．３以上２．８以下となる。 Also, assume that the operating value of the pressure ratio of the two-stage screw compressor varies in the range of 8 to 14, for example. Using formula (1), when the pressure ratio Pd2/Ps1 of the two-stage screw compressor is 14, the pressure ratio Pi/Ps1 of the pre-compressor body 1 is 3.74 (i.e., the pre-compressor body 1 , the intermediate pressure Pi=0.374 MPa). Although the volume ratio of the pre-compressor body 1 corresponding to the pressure ratio Pi/Ps1=3.74 (ideal value) is 2.6, the actual pressure ratio Pi/Ps1 is higher than the ideal value. The volume ratio of the machine body 1 is set to be 2.8. As a result, even if the operating value of the intermediate pressure changes with changes in the operating value of the pressure ratio of the two-stage screw compressor, the pressure in the working chamber in the compression stroke of the pre-compressor main body 1 is lower than the operating value of the intermediate pressure. not high. Therefore, under-compression does not occur. According to the consideration described above, the volume ratio of the pre-compressor main body 1 is 2.3 or more and 2.8 or less.

上述した通り、中間圧力の設定値が比較的高くなるように、前段圧縮機本体１の容積比が設定されている。そして、二段スクリュー圧縮機の圧力比の運転値が比較的低くなり、これに伴って中間圧力の運転値が比較的低くなれば、前段圧縮機本体１が過圧縮（詳細には、圧縮行程の作動室の圧力が中間圧力より高い状態）となる。そのため、本実施形態の他の特徴として、前段圧縮機本体１は、圧縮行程の雄ロータ側作動室Ｘ２と中間流路３を連通する前段弁孔１２Ａと、前段弁孔１２Ａに配置された前段リリース弁１３Ａと、圧縮行程の雌ロータ側作動室Ｙ２と中間流路３を連通する前段弁孔１２Ｂと、前段弁孔１２Ｂに配置された前段リリース弁１３Ｂとを備える。 As described above, the volume ratio of the pre-compressor main body 1 is set so that the set value of the intermediate pressure is relatively high. Then, if the operating value of the pressure ratio of the two-stage screw compressor becomes relatively low, and accordingly the operating value of the intermediate pressure becomes relatively low, the pre-compressor main body 1 is overcompressed (specifically, the compression stroke The pressure in the working chamber of is higher than the intermediate pressure). Therefore, as another feature of the present embodiment, the pre-compressor body 1 includes a pre-stage valve hole 12A communicating between the male rotor side working chamber X2 in the compression stroke and the intermediate flow path 3, and a pre-stage valve hole 12A arranged in the pre-stage valve hole 12A. It has a release valve 13A, a front stage valve hole 12B communicating between the female rotor side working chamber Y2 in the compression stroke and the intermediate flow path 3, and a front stage release valve 13B arranged in the front stage valve hole 12B.

図２で示すように、前段弁孔１２Ａは、雄ロータ５Ａの軸方向に対して垂直な方向に延在するように形成されている。同様に、前段弁孔１２Ｂは、雌ロータ６Ａの軸方向に対して垂直な方向に延在するように形成されている。 As shown in FIG. 2, the pre-stage valve hole 12A is formed to extend in a direction perpendicular to the axial direction of the male rotor 5A. Similarly, the front stage valve hole 12B is formed to extend in a direction perpendicular to the axial direction of the female rotor 6A.

図３で示すように、前段弁孔１２Ａ，１２Ｂの弁座（段差面）は、雄ロータ５Ａの中心と雌ロータ６Ａの中心を結ぶ直線に対して平行な方向に延在するように形成されている。但し、前段弁孔１２Ａ，１２Ｂにおける座面より作動室側の容積を低減するため、前段弁孔１２Ａ，１２Ｂの弁座は、雄ロータ５Ａの中心と雌ロータ６Ａの中心を結ぶ直線に対して傾斜させてもよい。 As shown in FIG. 3, the valve seats (step surfaces) of the front stage valve holes 12A and 12B are formed so as to extend in a direction parallel to a straight line connecting the center of the male rotor 5A and the center of the female rotor 6A. ing. However, in order to reduce the volume on the working chamber side of the seating surfaces of the front stage valve holes 12A and 12B, the valve seats of the front stage valve holes 12A and 12B are positioned so that they You can tilt it.

前段リリース弁１３Ａは、前段弁孔１２Ａの弁座に配置された弁体１４Ａと、弁体１４Ａの抑えであるリテーナ１５Ａと、弁体１４Ａ及びリテーナ１５Ａを固定するボルト１６Ａとを有する。そして、圧縮行程の雄ロータ側作動室Ｘ２の圧力が中間圧力より低い場合は、弁体１４Ａが変形しないため、前段弁孔１２Ａを遮断状態とする。一方、圧縮行程の雄ロータ側作動室Ｘ２の圧力が中間圧力より高い場合は、弁体１４Ａが変形するため、前段弁孔１２Ａを連通状態とする。これにより、圧縮行程の雄ロータ側作動室Ｘ２の圧力を中間圧力まで低減することができる。 The pre-stage release valve 13A has a valve body 14A arranged on the valve seat of the pre-stage valve hole 12A, a retainer 15A that holds the valve body 14A, and bolts 16A that fix the valve body 14A and the retainer 15A. When the pressure in the male rotor side working chamber X2 in the compression stroke is lower than the intermediate pressure, the valve body 14A does not deform, so the front stage valve hole 12A is closed. On the other hand, when the pressure in the male rotor side working chamber X2 in the compression stroke is higher than the intermediate pressure, the valve body 14A is deformed, so that the front stage valve hole 12A is brought into the communicating state. As a result, the pressure in the male rotor side working chamber X2 in the compression stroke can be reduced to the intermediate pressure.

同様に、前段リリース弁１３Ｂは、前段弁孔１２Ｂの弁座に配置された弁体１４Ｂと、弁体１４Ｂの抑えであるリテーナ１５Ｂと、弁体１４Ｂ及びリテーナ１５Ｂを固定するボルト１６Ｂとを有する。そして、圧縮行程の雌ロータ側作動室Ｙ２の圧力が中間圧力より低い場合は、弁体１４Ｂが変形しないため、前段弁孔１２Ｂを遮断状態とする。一方、圧縮行程の雌ロータ側作動室Ｙ２の圧力が中間圧力より高い場合は、弁体１４Ｂが変形するため、前段弁孔１２Ｂを連通状態とする。これにより、圧縮行程の雌ロータ側作動室Ｙ２の圧力を中間圧力まで低減することができる。 Similarly, the pre-stage release valve 13B has a valve body 14B arranged on the valve seat of the pre-stage valve hole 12B, a retainer 15B that restrains the valve body 14B, and bolts 16B that fix the valve body 14B and the retainer 15B. . When the pressure in the female rotor side working chamber Y2 in the compression stroke is lower than the intermediate pressure, the valve body 14B is not deformed, so the front stage valve hole 12B is closed. On the other hand, when the pressure in the female rotor side working chamber Y2 in the compression stroke is higher than the intermediate pressure, the valve body 14B is deformed, so that the front stage valve hole 12B is brought into a communicating state. As a result, the pressure in the female rotor side working chamber Y2 in the compression stroke can be reduced to the intermediate pressure.

したがって、本実施形態では、中間圧力の変化に応じて前段圧縮機本体１の圧縮行程の作動室の圧力を調整して、効率を向上させることができる。また、本実施形態では、前段リリース弁１３Ａ，１３Ｂは、前段圧縮機本体１の圧縮行程の作動室の圧力と中間圧力との差圧によって作動する。そのため、オイルフリー式の（詳細には、作動室に油を供給しない）圧縮機に好適である。 Therefore, in this embodiment, it is possible to improve the efficiency by adjusting the pressure in the working chamber in the compression stroke of the precompressor main body 1 according to the change in the intermediate pressure. Further, in the present embodiment, the front release valves 13A and 13B are actuated by the differential pressure between the pressure in the working chamber during the compression stroke of the front compressor main body 1 and the intermediate pressure. Therefore, it is suitable for an oil-free compressor (specifically, no oil is supplied to the working chamber).

なお、第１の実施形態において、前段弁孔１２Ａは、雄ロータ５Ａの軸方向に対して垂直な方向に延在するように形成され、前段弁孔１２Ｂは、雌ロータ６Ａの軸方向に対して垂直な方向に延在するように形成された場合を例にとって説明したが、これに限られず、本発明の趣旨を逸脱しない範囲内で変形が可能である。例えば図４で示す変形例のように、前段弁孔１２Ａは、雄ロータ５Ａの歯溝の延在方向に沿って形成され、前段弁孔１２Ｂは、雌ロータ６Ａの歯溝の延在方向に沿って形成されてもよい。この変形例では、第１の実施形態と比べ、隣接する圧縮行程の雄ロータ側作動室が前段弁孔１２Ａを介して連通する時間を低減することができる。また、第１の実施形態と比べ、隣接する圧縮行程の雌ロータ側作動室が前段弁孔１２Ｂを介して連通する時間を低減することができる。したがって、圧縮動作の阻害を抑制することができる。 In the first embodiment, the front valve hole 12A is formed to extend in a direction perpendicular to the axial direction of the male rotor 5A, and the front valve hole 12B is formed to extend in the axial direction of the female rotor 6A. Although the case where it is formed so as to extend in a vertical direction has been described as an example, it is not limited to this and can be modified without departing from the gist of the present invention. For example, as in the modification shown in FIG. 4, the front valve hole 12A is formed along the extending direction of the tooth spaces of the male rotor 5A, and the front valve hole 12B is formed along the extending direction of the tooth spaces of the female rotor 6A. may be formed along In this modified example, compared to the first embodiment, it is possible to reduce the time during which the adjacent male rotor side working chambers in the compression stroke are communicated with each other via the pre-stage valve hole 12A. In addition, compared to the first embodiment, it is possible to reduce the time during which the adjacent female rotor side working chambers in the compression stroke are communicated with each other via the pre-stage valve hole 12B. Therefore, inhibition of compression operation can be suppressed.

本発明の第２の実施形態を、図５を用いて説明する。なお、本実施形態において、第１の実施形態と同等の部分は同一の符号を付し、適宜、説明を省略する。 A second embodiment of the present invention will be described with reference to FIG. In addition, in this embodiment, the same code|symbol is attached|subjected to the part equivalent to 1st Embodiment, and description is abbreviate|omitted suitably.

図５は、本実施形態における二段スクリュー圧縮機の構造を表す鉛直断面図である。 FIG. 5 is a vertical sectional view showing the structure of the two-stage screw compressor in this embodiment.

本実施形態では、後段圧縮機本体２は、圧縮行程の雄ロータ側作動室Ｘ５と吐出流路４を連通する後段弁孔１７Ａと、後段弁孔１７Ａに配置された後段リリース弁１８Ａと、圧縮行程の雌ロータ側作動室と吐出流路４を連通する後段弁孔１７Ｂ（図示せず）と、後段弁孔１７Ｂに配置された後段リリース弁１８Ｂ（図示せず）とを備える。なお、後段弁孔１７Ａ，１７Ｂは、上述した前段弁孔１２Ａ，１２Ｂと同様の構造であるため、その説明を省略する。 In this embodiment, the rear compressor main body 2 includes a rear valve hole 17A that communicates the male rotor side working chamber X5 in the compression stroke with the discharge passage 4, a rear release valve 18A that is arranged in the rear valve hole 17A, a compression A post-stage valve hole 17B (not shown) that communicates the female rotor-side working chamber of the stroke with the discharge passage 4, and a post-stage release valve 18B (not shown) arranged in the post-stage valve hole 17B. Since the rear valve holes 17A and 17B have the same structure as the front valve holes 12A and 12B described above, the description thereof will be omitted.

後段リリース弁１８Ａは、上述した前段リリース弁１３Ａと同様の構造である。すなわち、後段弁孔１７Ａの弁座に配置された弁体と、弁体の抑えであるリテーナと、弁体及びリテーナを固定するボルトとを有する。そして、圧縮行程の雄ロータ側作動室Ｘ５の圧力が吐出流路４の圧力より低い場合は、弁体が変形しないため、後段弁孔１７Ａを遮断状態とする。一方、圧縮行程の雄ロータ側作動室Ｘ５の圧力が吐出流路４の圧力より高い場合は、弁体が変形するため、後段弁孔１７Ａを連通状態とする。これにより、圧縮行程の雄ロータ側作動室Ｘ５の圧力を吐出流路４の圧力まで低減することができる。 The post-release valve 18A has the same structure as the above-described pre-release valve 13A. That is, it has a valve disc arranged on the valve seat of the rear stage valve hole 17A, a retainer for holding the valve disc, and bolts for fixing the valve disc and the retainer. When the pressure in the male rotor side working chamber X5 in the compression stroke is lower than the pressure in the discharge passage 4, the valve body does not deform, so that the rear stage valve hole 17A is closed. On the other hand, when the pressure in the male rotor side working chamber X5 in the compression stroke is higher than the pressure in the discharge passage 4, the valve body deforms, so that the rear stage valve hole 17A is brought into communication. As a result, the pressure in the male rotor-side working chamber X5 during the compression stroke can be reduced to the pressure in the discharge passage 4 .

同様に、後段リリース弁１８Ｂは、上述した前段リリース弁１３Ｂと同様の構造である。すなわち、後段弁孔１７Ｂの弁座に配置された弁体と、弁体の抑えであるリテーナと、弁体及びリテーナを固定するボルトとを有する。そして、圧縮行程の雌ロータ側作動室の圧力が吐出流路４の圧力より低い場合は、弁体が変形しないため、後段弁孔１７Ｂを遮断状態とする。一方、圧縮行程の雌ロータ側作動室の圧力が吐出流路４の圧力より高い場合は、弁体が変形するため、後段弁孔１７Ｂを連通状態とする。これにより、圧縮行程の雌ロータ側作動室の圧力を吐出流路４の圧力まで低減することができる。 Similarly, the post-release valve 18B has the same structure as the pre-release valve 13B described above. That is, it has a valve body arranged on the valve seat of the rear stage valve hole 17B, a retainer for holding the valve body, and bolts for fixing the valve body and the retainer. When the pressure in the working chamber on the female rotor side in the compression stroke is lower than the pressure in the discharge passage 4, the valve body does not deform, so that the rear stage valve hole 17B is closed. On the other hand, when the pressure in the working chamber on the female rotor side in the compression stroke is higher than the pressure in the discharge passage 4, the valve element deforms, so that the rear stage valve hole 17B is brought into communication. As a result, the pressure in the female rotor side working chamber during the compression stroke can be reduced to the pressure in the discharge passage 4 .

したがって、本実施形態では、第１の実施形態と同様の効果に加え、吐出流路４の圧力の変化に応じて後段圧縮機本体２の圧縮行程の作動室の圧力を調整して、効率を向上させるという効果を得ることができる。 Therefore, in this embodiment, in addition to the same effect as the first embodiment, the pressure in the working chamber in the compression stroke of the post-compressor main body 2 is adjusted in accordance with the change in the pressure in the discharge passage 4 to improve the efficiency. You can get the effect of improving.

なお、第１及び第２の実施形態において、各段圧縮機本体は、２つのスクリューロータを備えた場合を例にとって説明したが、これに限られず、本発明の趣旨を逸脱しない範囲内で変形が可能である。例えば、各段圧縮機本体は、１つ又は３つのスクリューロータを備えたものでもよい。 In the first and second embodiments, the main body of each stage compressor has two screw rotors. is possible. For example, each stage compressor body may have one or three screw rotors.

また、第１及び第２の実施形態において、本発明の適用対象として二段スクリュー圧縮機を例にとって説明したが、これに限られず、二段スクロール圧縮機であってもよい。このような変形例を、図６又は図７を用いて説明する。なお、本変形例において、第１又は第２の実施形態と同等の部分は同一の符号を付し、適宜、説明を省略する。 In addition, in the first and second embodiments, the two-stage screw compressor was described as an example of application of the present invention, but the present invention is not limited to this, and may be a two-stage scroll compressor. Such a modified example will be described with reference to FIG. 6 or FIG. In addition, in this modified example, the same code|symbol is attached|subjected to the part equivalent to 1st or 2nd embodiment, and description is abbreviate|omitted suitably.

図６で示す変形例では、前段圧縮機本体１Ａは、渦巻状のラップを有する固定スクロール部材２０Ａと、固定スクロール部材２０Ａのラップと噛み合って作動室を形成する渦巻き状のラップを有する旋回スクロール部材２１Ａと、旋回スクロール部材２１Ａに係合されたクランク軸２２Ａと、固定スクロール部材２０Ａの下側に設けられて旋回スクロール部材２１Ａを収納するケーシング２３Ａと、固定スクロール部材２０Ａの上側（吐出側）に設けられたカバー２４Ａとを備える。 In the modification shown in FIG. 6, the pre-compressor main body 1A includes a fixed scroll member 20A having a spiral wrap and an orbiting scroll member having a spiral wrap that meshes with the wrap of the fixed scroll member 20A to form a working chamber. 21A, a crankshaft 22A engaged with the orbiting scroll member 21A, a casing 23A provided below the fixed scroll member 20A and housing the orbiting scroll member 21A, and above (discharge side) the fixed scroll member 20A. and a provided cover 24A.

旋回スクロール部材２１Ａは、オルダムリング（図示せず）で自転することなく旋回可能に支持され、クランク軸２２Ａは、軸受（図示せず）で回転可能に支持されている。クランク軸２２Ａは、モータ（図示せず）によって回転して、旋回スクロール部材２１Ａを旋回させる。 The orbiting scroll member 21A is rotatably supported by an Oldham ring (not shown) without rotating, and the crankshaft 22A is rotatably supported by bearings (not shown). The crankshaft 22A is rotated by a motor (not shown) to orbit the orbiting scroll member 21A.

旋回スクロール部材２１Ａの旋回に伴い、作動室は、径方向の外側から内側へ移動しつつ、その容積が変化する。これにより、吸入行程、圧縮行程、吐出行程を順次行うようになっている。詳しく説明すると、吸入行程の作動室は、その容積が増加して、吸入口２５Ａから気体を吸入する。圧縮行程の作動室Ｚ１は、その容積が縮小して、気体を圧縮する。吐出行程の作動室Ｚ２は、吐出口２６Ａから圧縮気体を吐出する。 As the orbiting scroll member 21A orbits, the volume of the working chamber changes while moving from the outside to the inside in the radial direction. As a result, a suction stroke, a compression stroke, and a discharge stroke are sequentially performed. Specifically, in the suction stroke, the working chamber increases in volume and sucks gas from the suction port 25A. The volume of the working chamber Z1 in the compression stroke is reduced to compress the gas. The working chamber Z2 in the discharge stroke discharges the compressed gas from the discharge port 26A.

後段圧縮機本体２Ａは、渦巻状のラップを有する固定スクロール部材２０Ｂと、固定スクロール部材２０Ｂのラップと噛み合って作動室を形成する渦巻き状のラップを有する旋回スクロール部材２１Ｂと、旋回スクロール部材２１Ｂに係合されたクランク軸２２Ｂと、固定スクロール部材２０Ｂの下側に設けられて旋回スクロール部材２１Ｂを収納するケーシング２３Ｂと、固定スクロール部材２０Ｂの上側（吐出側）に設けられたカバー２４Ｂとを備える。 The post-compressor main body 2A includes a fixed scroll member 20B having a spiral wrap, an orbiting scroll member 21B having a spiral wrap that meshes with the wrap of the fixed scroll member 20B to form a working chamber, and an orbiting scroll member 21B. It comprises an engaged crankshaft 22B, a casing 23B provided below the fixed scroll member 20B to accommodate the orbiting scroll member 21B, and a cover 24B provided above (discharge side) the fixed scroll member 20B. .

旋回スクロール部材２１Ｂは、オルダムリング（図示せず）で自転することなく旋回可能に支持され、クランク軸２２Ｂは、軸受（図示せず）で回転可能に支持されている。クランク軸２２Ｂは、モータ（図示せず）によって回転して、旋回スクロール部材２１Ｂを旋回させる。 The orbiting scroll member 21B is rotatably supported by an Oldham ring (not shown) without rotating, and the crankshaft 22B is rotatably supported by bearings (not shown). The crankshaft 22B is rotated by a motor (not shown) to orbit the orbiting scroll member 21B.

旋回スクロール部材２１Ｂの旋回に伴い、作動室は、径方向の外側から内側へ移動しつつ、その容積が変化する。これにより、吸入行程、圧縮行程、吐出行程を順次行うようになっている。詳しく説明すると、吸入行程の作動室は、その容積が増加して、吸入口２５Ｂから気体を吸入する。圧縮行程の作動室Ｚ３は、その容積が縮小して、気体を圧縮する。吐出行程の作動室Ｚ４は、吐出口２６Ｂから圧縮気体を吐出する。 As the orbiting scroll member 21B orbits, the volume of the working chamber changes while moving from the outside to the inside in the radial direction. As a result, a suction stroke, a compression stroke, and a discharge stroke are sequentially performed. More specifically, the working chamber in the suction stroke increases in volume and sucks gas from the suction port 25B. The volume of the working chamber Z3 in the compression stroke is reduced to compress the gas. The working chamber Z4 in the discharge stroke discharges the compressed gas from the discharge port 26B.

本変形例では、第１及び第２の実施形態と同様、中間圧力の設定値が比較的高くなるように、前段圧縮機本体１Ａの容積比が設定されている。前段圧縮機本体１Ａは、圧縮行程の作動室Ｚ１と中間流路３を連通する前段弁孔１２と、前段弁孔１２に配置された前段リリース弁１３とを備える。そして、圧縮行程の作動室Ｚ１の圧力が中間圧力より低い場合に、前段リリース弁１３は、前段弁孔１２を遮断状態とする。一方、圧縮行程の作動室Ｚ１の圧力が中間圧力より高い場合に、前段リリース弁１３は、前段弁孔１２を連通状態とする。これにより、圧縮行程の作動室Ｚ１の圧力を中間圧力まで低減することができる。したがって、第１及び第２の実施形態と同様、中間圧力の変化に応じて前段圧縮機本体１Ａの圧縮行程の作動室の圧力を調整して、効率を向上させることができる。 In this modification, as in the first and second embodiments, the volume ratio of the pre-compressor main body 1A is set so that the set value of the intermediate pressure is relatively high. The front-stage compressor body 1A includes a front-stage valve hole 12 that communicates the working chamber Z1 in the compression stroke with the intermediate flow path 3, and a front-stage release valve 13 arranged in the front-stage valve hole 12. Then, when the pressure in the working chamber Z1 in the compression stroke is lower than the intermediate pressure, the front release valve 13 closes the front valve hole 12 . On the other hand, when the pressure in the working chamber Z1 in the compression stroke is higher than the intermediate pressure, the front release valve 13 brings the front valve hole 12 into communication. As a result, the pressure in the working chamber Z1 during the compression stroke can be reduced to the intermediate pressure. Therefore, as in the first and second embodiments, efficiency can be improved by adjusting the pressure in the working chamber in the compression stroke of the front compressor main body 1A according to the change in the intermediate pressure.

図７で示す変形例では、第２の実施形態と同様、後段圧縮機本体２Ａは、圧縮行程の作動室Ｚ３と吐出流路４を連通する後段弁孔１７と、後段弁孔１７に配置された後段リリース弁１８とを備える。そして、圧縮行程の作動室Ｚ３の圧力が吐出流路４の圧力より低い場合に、後段リリース弁１８は、後段弁孔１７を遮断状態とする。一方、圧縮行程の作動室Ｚ３の圧力が吐出流路４の圧力より高い場合に、後段リリース弁１８は、後段弁孔１７を連通状態とする。これにより、圧縮行程の作動室Ｚ３の圧力を吐出流路４の圧力まで低減することができる。したがって、第２の実施形態と同様、吐出流路４の圧力の変化に応じて後段圧縮機本体２Ａの圧縮行程の作動室の圧力を調整して、効率を向上させることができる。 In the modification shown in FIG. 7, as in the second embodiment, the rear compressor main body 2A is arranged in the rear valve hole 17 communicating between the working chamber Z3 in the compression stroke and the discharge passage 4, and the rear valve hole 17. and a post-stage release valve 18 . When the pressure in the working chamber Z3 during the compression stroke is lower than the pressure in the discharge passage 4, the rear release valve 18 closes the rear valve hole 17. As shown in FIG. On the other hand, when the pressure in the working chamber Z3 in the compression stroke is higher than the pressure in the discharge passage 4, the rear release valve 18 brings the rear valve hole 17 into communication. As a result, the pressure in the working chamber Z3 during the compression stroke can be reduced to the pressure in the discharge passage 4. FIG. Therefore, as in the second embodiment, the pressure in the working chamber in the compression stroke of the post-compressor main body 2A can be adjusted in accordance with the change in the pressure in the discharge passage 4 to improve the efficiency.

なお、上述した実施形態及び変形例において、前段リリース弁（又は後段リリース弁）は、圧縮行程の作動室の圧力と中間圧力（又は吐出流路の圧力）との差圧によって変形する弁体を有する場合を例にとって説明したが、これに限られず、本発明の趣旨を逸脱しない範囲内で変形が可能である。このような変形例を、図８を用いて説明する。なお、図８においては、代表として前段リリース弁１３を示すものの、他の前段リリース弁又は後段リリース弁であってもよい。 In the embodiments and modifications described above, the front release valve (or the rear release valve) has a valve body that deforms due to the pressure difference between the pressure in the working chamber during the compression stroke and the intermediate pressure (or the pressure in the discharge passage). Although the case has been described as an example, it is not limited to this, and modifications are possible without departing from the gist of the present invention. Such a modified example will be described with reference to FIG. Although FIG. 8 shows the front release valve 13 as a representative, other front release valves or rear release valves may be used.

本変形例では、前段リリース弁（又は後段リリース弁）は、弁体３０と、弁体３０を作動室側（図８の下側）へ付勢するバネ３１と、弁体３０及びバネ３１の抑えであるリテーナ３２と、リテーナ３２を固定するボルト３４とを有する。そして、圧縮行程の作動室の圧力が中間圧力（又は吐出流路の圧力）とバネ３１の付勢力の総和より低い場合は、弁体３０が作動室側に位置して前段弁孔（又は後段弁孔）を遮断状態とし、圧縮行程の作動室の圧力が中間流路の圧力（又は吐出流路の圧力）とバネ３１の付勢力の総和より高い場合は、弁体３０が中間流路側（又は吐出流路側）に位置して前段弁孔（又は後段弁孔）を連通状態とする。このような変形例においても、上記同様の効果を得ることができる。 In this modification, the front release valve (or the rear release valve) includes a valve body 30, a spring 31 that biases the valve body 30 toward the working chamber side (lower side in FIG. 8), and the valve body 30 and the spring 31. It has a retainer 32 as a restraint and bolts 34 for fixing the retainer 32 . When the pressure in the working chamber in the compression stroke is lower than the sum of the intermediate pressure (or the pressure in the discharge passage) and the biasing force of the spring 31, the valve element 30 is positioned on the working chamber side and the front stage valve hole (or the rear stage valve hole) is closed. valve hole) is closed and the pressure in the working chamber in the compression stroke is higher than the sum of the pressure in the intermediate flow path (or the pressure in the discharge flow path) and the biasing force of the spring 31, the valve body 30 is positioned on the side of the intermediate flow path ( or the discharge channel side) to bring the front stage valve hole (or the rear stage valve hole) into a communicating state. Even in such a modified example, the same effect as described above can be obtained.

なお、以上においては、本発明の適用対象として、２つの圧縮機本体を備えた二段圧縮機を例にとって説明したが、これに限られず、３つ以上の圧縮機本体を備えた多段圧縮機でもよい。具体例の一つである三段圧縮機について詳述する。 In the above description, the present invention is applied to a two-stage compressor having two compressor bodies. It's okay. A three-stage compressor, which is one of the specific examples, will be described in detail.

三段圧縮機は、第１段圧縮機本体と、第１段圧縮機本体で圧縮された気体を更に圧縮する第２段圧縮機本体と、第２段圧縮機本体で圧縮された気体を更に圧縮する第３段圧縮機本体と、第１段圧縮機本体の吐出側と第２段圧縮機本体の吸入側を接続する第１中間流路と、第２段圧縮機本体の吐出側と第３段圧縮機本体の吸入側を接続する第２中間流路と、第３段圧縮機本体の吐出側に接続された吐出流路とを備える。 The three-stage compressor includes a first-stage compressor body, a second-stage compressor body that further compresses the gas compressed by the first-stage compressor body, and a second-stage compressor body that further compresses the gas compressed by the second-stage compressor body. a third-stage compressor body to be compressed; a first intermediate flow path connecting the discharge side of the first-stage compressor body and the suction side of the second-stage compressor body; A second intermediate flow path connecting the suction side of the three-stage compressor main body and a discharge flow path connected to the discharge side of the third-stage compressor main body are provided.

そして、第１段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と第１中間流路を連通する第１段弁孔（前段弁孔）と、第１段弁孔に配置された第１段リリース弁（前段リリース弁）とを設けてもよい。また、第２段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と第２中間流路を連通する第２段弁孔（前段弁孔）と、第２段弁孔に配置された第２段リリース弁（前段リリース弁）とを設けてもよい。また、第３段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と吐出流路を連通する第３段弁孔（後段弁孔）と、第３段弁孔に配置された第３段リリース弁（後段リリース弁）とを設けてもよい。 A first stage valve hole (previous stage valve hole) that communicates the first intermediate passage with a working chamber for a compression stroke that is different from the working chamber for a discharge stroke of the first stage compressor main body, and is arranged in the first stage valve hole. A first stage release valve (pre-stage release valve) may be provided. In addition, a second stage valve hole (previous stage valve hole) that communicates the second intermediate passage with a working chamber for a compression stroke that is different from the working chamber for a discharge stroke of the second stage compressor main body, and is arranged in the second stage valve hole. A second stage release valve (previous stage release valve) may be provided. Also, a third stage valve hole (rear stage valve hole) that communicates a discharge passage with a working chamber for a compression stroke different from the working chamber for a discharge stroke of the third stage compressor main body, and A third stage release valve (later stage release valve) may be provided.

１，１Ａ…前段圧縮機本体、２，２Ａ…後段圧縮機本体、３…中間流路、４…吐出流路、５Ａ，５Ｂ…雄ロータ（スクリューロータ）、６Ａ，６Ｂ…雌ロータ（スクリューロータ）、７Ａ，７Ｂ…ケーシング、１２，１２Ａ，１２Ｂ…前段弁孔、１３，１３Ａ，１３Ｂ…前段リリース弁、１７，１７Ａ，１７Ｂ…後段弁孔、１８，１８Ａ，１８Ｂ…後段リリース弁 1, 1A front compressor main body, 2, 2A rear compressor main body, 3 intermediate flow path, 4 discharge flow path, 5A, 5B male rotor (screw rotor), 6A, 6B female rotor (screw rotor) ), 7A, 7B ... casing, 12, 12A, 12B ... front stage valve hole, 13, 13A, 13B ... front stage release valve, 17, 17A, 17B ... rear stage valve hole, 18, 18A, 18B ... rear stage release valve

Claims

前段圧縮機本体と、前記前段圧縮機本体で圧縮された気体を更に圧縮する後段圧縮機本体と、前記前段圧縮機本体の吐出側と前記後段圧縮機本体の吸入側の間で接続された中間流路と、前記後段圧縮機本体の吐出側に接続された吐出流路と、を備えた多段圧縮機において、
前記前段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と前記中間流路を連通する前段弁孔と、
前記前段弁孔に配置され、前記前段圧縮機本体の前記圧縮行程の作動室の圧力と前記中間流路の圧力との差圧によって作動する前段リリース弁と、
前記後段圧縮機本体の吐出行程の作動室とは異なる圧縮行程の作動室と前記吐出流路の間で接続された後段弁孔と、
前記後段弁孔に配置され、前記後段圧縮機本体の前記圧縮行程の作動室の圧力と前記吐出流路の圧力との差圧によって作動する後段リリース弁とを備え、
前記前段リリース弁は、前記前段圧縮機本体の前記圧縮行程の作動室の圧力が前記中間流路の圧力より低い場合に前記前段弁孔を遮断状態とし、前記前段圧縮機本体の前記圧縮行程の作動室の圧力が前記中間流路の圧力より高い場合に前記前段弁孔を連通状態とし、
前記後段リリース弁は、前記後段圧縮機本体の前記圧縮行程の作動室の圧力が前記吐出流路の圧力より低い場合に前記後段弁孔を遮断状態とし、前記後段圧縮機本体の前記圧縮行程の作動室の圧力が前記吐出流路の圧力より高い場合に前記後段弁孔を連通状態とすることを特徴とする多段圧縮機。 a front compressor body, a rear compressor body for further compressing the gas compressed by the front compressor body, and an intermediate connected between the discharge side of the front compressor body and the suction side of the rear compressor body. A multi-stage compressor comprising a flow path and a discharge flow path connected to the discharge side of the post-compressor main body ,
a pre-stage valve hole that communicates the intermediate passage with a working chamber for a compression stroke that is different from a working chamber for a discharge stroke of the pre-stage compressor main body;
a pre-stage release valve disposed in the pre-stage valve hole and operated by a differential pressure between the pressure in the working chamber of the compression stroke of the pre-compressor main body and the pressure in the intermediate passage ;
a post-stage valve hole connected between a compression stroke working chamber different from the discharge stroke working chamber of the post-compressor main body and the discharge passage;
a post-stage release valve disposed in the post-stage valve hole and operated by a differential pressure between a pressure in the working chamber of the compression stroke of the post-compressor main body and a pressure in the discharge passage ;
The pre-stage release valve shuts off the pre-stage valve hole when the pressure in the working chamber during the compression stroke of the pre-compressor main body is lower than the pressure in the intermediate flow passage, and the pre-stage release valve closes the pre-stage valve hole during the compression stroke of the pre-compressor main body. when the pressure in the working chamber is higher than the pressure in the intermediate passage, the pre-stage valve hole is brought into communication ;
The latter release valve shuts off the latter valve hole when the pressure in the working chamber of the latter compressor main body during the compression stroke is lower than the pressure of the discharge flow path, thereby closing the latter compressor main body during the compression stroke. A multi-stage compressor , wherein the rear stage valve hole is brought into communication when the pressure in the working chamber is higher than the pressure in the discharge passage .

請求項１に記載の多段圧縮機において、
前記前段圧縮機本体は、スクリューロータと、前記スクリューロータを収納してその歯溝に作動室を形成するケーシングとを備え、
前記前段弁孔は、前記スクリューロータの歯溝の延在方向に沿って形成されたことを特徴とする多段圧縮機。 In the multistage compressor according to claim 1,
The front-stage compressor main body includes a screw rotor and a casing housing the screw rotor and forming a working chamber in a tooth space thereof,
A multi-stage compressor, wherein the pre-stage valve hole is formed along an extending direction of tooth grooves of the screw rotor.

請求項１又は２記載の多段圧縮機において、
前記前段圧縮機本体の容積比は、２．３以上２．８以下であることを特徴とする多段圧縮機。 In the multistage compressor according to claim 1 or 2 ,
A multi-stage compressor, wherein the volume ratio of the front-stage compressor main body is 2.3 or more and 2.8 or less.