Compressor

A check valve includes a valve seat portion and a reed valve element and is received in a receiving hole of an intermediate pressure refrigerant supply passage that is placed adjacent to a flow inlet of an injection port, through which a refrigerant of an intermediate pressure is injected into a compression chamber. A center of the flow inlet of the injection port is offset from a central axis of a valve seat passage formed in the valve seat portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2013/002042 filed on Mar. 26, 2013 and published in Japanese as WO 2013/145713 A1 on Oct. 3, 2013. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2012-081327 filed on Mar. 30, 2012.

TECHNICAL FIELD

The present disclosure relates to a compressor that has a compression chamber, into which an intermediate pressure gas is injected.

BACKGROUND ART

As disclosed in, for example, Patent Literature 1, there is known a compressor that supercharges a compression subject fluid upon injection of the compression subject fluid into the compressor. Known electric compressors for refrigerating and air conditioning include an electric compressor having a compressing unit of a reciprocating type, an electric compressor having a compressing unit of a rotary type, and an electric compressor having a compressing unit of a scroll type. Among these types, the compressor of the scroll type has been practically used by utilizing the characteristics of the high efficiency, the low noise level and the low vibration level. In the compressor of the scroll type, a refrigerant gas of an intermediate pressure is injected through a check valve into a compression chamber formed between a stationary scroll and an orbiting scroll to implement the stable and efficient gas injection by utilizing the moderate compression that is the characteristic of the compressor of the scroll type. However, in a case where a path, which extends from the check valve to the compression chamber formed between the stationary scroll and the orbiting scroll, is complicated and is long, it is known that a dead volume becomes large to cause adverse influence on the compression efficiency, an increase in the amount of intrusion of a lubricating oil, unstableness of the lubrication caused by deterioration of draining, and unstableness of the performance.

In the prior art technique of Patent Literature 1, an injection port is formed in an end plate of the stationary scroll in such a manner that the injection port penetrates through the end plate from a back surface side of the end plate to the compression chamber in a wall thickness direction of the end plate. A block, to which an injection pipe is connected, is engaged with an outer surface of the end plate of the stationary scroll, which corresponds to the injection port, and a check valve chamber is formed between the end plate and the block. A reed valve element is fixed with bolts to a guide inlet of the block, which is connected with the injection pipe, to form a check valve. In this instance, the guide inlet of the injection pipe and the injection port are coaxially arranged. Furthermore, a valve stopper of the reed valve element is formed in a portion of the check valve chamber.

The prior art technique of Patent Literature 1 is the one that has a simple structure and a relatively small dead volume and can limit re-expansion of a compressible fluid and outflow of a lubricant oil. However, the following disadvantages (1)-(3) have been encountered.

(1) In the prior art technique, attention is not given to a relationship between a lifting direction of the reed valve element and a location of the injection port, so that depending on the positional relationship discussed above, a flow passage resistance may possibly become high, and an injection flow quantity may possibly be reduced. Furthermore, a size of the reed valve element is large. Therefore, when it is desirable to further reduce the dead volume, there will be a mounting difficulty.

(2) In the prior art technique, the bolts, which fix the reed valve element, are required. Therefore, the component costs are increased. Furthermore, the number of assembling steps is increased, and thereby the assembling costs are increased.

(3) Normally, in the case where the reed valve element is used, the valve stopper is required. In the prior art technique, there is the disclosure about the formation of the valve stopper, and the formation of the valve stopper requires a separate processing step, which is separate from a processing step of the refrigerant passage.

Besides the above prior art technique, Patent Literature 2 discloses a compressor of a refrigeration cycle, into which an intermediate pressure gas is injected. In Patent Literature 2, a reed valve element, which opens or closes in a direction perpendicular to an axial direction of an injection port that projects from a back surface of a stationary scroll, is inserted into the injection port, so that a dead volume cannot be reduced, and there is a disadvantage with respect to provision of an axial space. Patent Literature 3 recites a compressor, in which liquid injection is executed, and a plug is fitted into a connecting conduit, which is communicated with an injection port, to limit gasification of the liquid. In this compressor, a dead volume cannot be reduced when the dead volume of the entire flow passage is considered.

CITATION LIST

Patent Literatures

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

An objective of the present disclosure relates to the above disadvantages and is to provide a compressor, which has a compression chamber for receiving an intermediate pressure gas injected thereto, while the compressor can reduce a dead volume and can improve an injection characteristic.

Solution to Problem

A compressor according to the present disclosure has a housing that includes: a low pressure refrigerant supply passage that conducts refrigerant, which has a low pressure; a compression chamber that compresses the refrigerant supplied from the low pressure refrigerant supply passage to a high pressure, which is higher than the low pressure, and discharges the compressed refrigerant out of the compression chamber; and an intermediate pressure refrigerant supply passage that is communicatable with the compression chamber through an injection port to inject refrigerant, which has an intermediate pressure that is higher than the low pressure and is lower than the high pressure, into the compression chamber. The compressor has a check valve that is received in a receiving hole of the intermediate pressure refrigerant supply passage, which is placed adjacent to a flow inlet of the injection port. The check valve includes a valve seat portion and a reed valve element. The valve seat portion has a valve seat and a valve seat passage, and the valve seat passage is located radially inward of the valve seat and extends through the valve seat portion to conduct the refrigerant therethrough. A center of the flow inlet of the injection port is offset from a central axis of the valve seat passage. The reed valve element is seatable against the valve seat to close the valve seat passage and is liftable from the valve seat to open the valve seat passage. A check valve chamber is formed in the receiving hole at a location between the valve seat portion and a wall surface of the receiving hole to receive at least a portion of the reed valve element when the reed valve element is lifted from the valve seat.

DESCRIPTION OF EMBODIMENT

An embodiment of the present disclosure will be described with reference to the drawings. In the following embodiment and modifications thereof described below, similar components are indicated by the same reference numerals and will not be redundantly described.

The embodiment of the present disclosure is an example, in which a principle of the present disclosure is applied to a refrigeration cycle, more specifically, a heat pump cycle of a hot-water supply system.FIG. 1is a descriptive view showing the heat pump cycle of the present embodiment. The heat pump cycle includes: a compressor1, which suctions and compresses a refrigerant; a heat exchanger (a water refrigerant heat exchanger)2, which exchanges heat between hot water and the refrigerant outputted from the compressor1; a first expansion valve3and a second expansion valve4, which depressurize the refrigerant outputted from the heat exchanger2; a heat exchanger (evaporator)5, which absorbs heat from external air to evaporate the refrigerant; and a gas-liquid separator6, which separates the refrigerant outputted from the heat exchanger5into a liquid phase refrigerant and a gas phase refrigerant, wherein the gas-liquid separator6stores excessive refrigerant and supplies the gas phase refrigerant to the compressor1through a refrigerant conduit38.

The heat pump cycle branches at a branch point7, which is located on a downstream side of the first expansion valve3and on an upstream side of the second expansion valve4, to supply the refrigerant gas of an intermediate pressure, which is once depressurized through the first expansion valve3, to the compressor1through an intermediate pressure conduit8. A refrigerant discharge passage54(seeFIG. 2) of the compressor1is connected to a refrigerant inlet47of an oil separator40through a refrigerant outlet54aand a refrigerant conduit48. The oil separator40has a function of separating lubricant oil from the compressed refrigerant, which is discharged from a housing30of the compressor1, and a function of returning the separated lubricant oil to the housing30through a conduit connecting member34.

In the embodiment of the present disclosure, the principle of the present disclosure is applied to the heat pump cycle of the hot-water supply system. Alternatively, the principle of the present disclosure may be applied to other systems or a refrigeration cycle (including a heat pump cycle) of other apparatuses. For example, the principle of the present disclosure may be applied to a refrigeration cycle of a vehicle air conditioning system or a refrigeration cycle of other industrial or domestic air conditioners. Furthermore, the embodiment of the present disclosure describes an example, in which the principle of the present disclosure is applied to the compressor1, which is constructed as a scroll compressor. However, the present disclosure is not limited to this, and the principle of the present disclosure may be applied to single stage compressors of other types. In addition, the principle of the present disclosure may be applied to a double stage compressor. Furthermore, in the heat pump cycle of the embodiment of the present disclosure, the gas-liquid separator6is provided on the downstream side of the heat exchanger5. However, it should be noted that the principle of the present disclosure may be applied to a heat pump cycle that does not have the gas-liquid separator6.

FIG. 2is a cross-sectional view of the compressor1of the embodiment of the present disclosure. The compressor1is an electric compressor of a scroll type and includes a compressing mechanism10, which compresses the refrigerant (refrigerant gas), and an electric motor device20, which drives the compressing mechanism10. The compressing mechanism10and the electric motor device20are arranged one after another in a top-to-bottom direction (vertical direction), so that the compressor of the present embodiment is formed as an upright type. In the present embodiment, although the compressor1is described as the upright type, the compressor1may be a horizontal type. The compressing mechanism10and the electric motor device20are received in the housing30. The electric motor device20includes a stator21and a rotor22. The stator21includes a stator core211and a stator coil212, and the stator coil212is wound around the stator core211.

An electric power is supplied to the stator coil212through power supply terminals23. The power supply terminals23are placed at an upper end part of the housing30. When the electric power is supplied to the stator coil212, a rotating magnetic field is applied to the rotor22to generate a rotational force at the rotor22, and thereby the rotor22is rotated together with the drive shaft25. The drive shaft25is configured into a cylindrical tubular body, and an oil supply passage251, which supplies the lubricant oil to slidable parts (lubrication subject parts) of the drive shaft25, is formed in an interior space of the drive shaft25. The oil supply passage251opens in a lower end surface of the drive shaft25and is closed by a closing member26at an upper end surface of the drive shaft25.

A flange252, which projects in a horizontal direction (a direction perpendicular to the axial direction), is formed in a portion of the drive shaft25, which projects from the rotor22on the lower side of the rotor22. A balance weight254is formed in the flange252. Balance weights221,222are also provided at upper and lower sides, respectively, of the rotor22. The drive shaft25is supported by bearings27,291. A middle housing29is configured into a cylindrical tubular form having inner and outer diameters, which are increased in a stepwise manner from the upper side toward the lower side of the middle housing29in the top-to-bottom direction. An outer peripheral surface of the middle housing29is fixed to a tubular member31of the housing30. An upper portion of the middle housing29forms the bearing291. A movable scroll (also referred to as an orbiting scroll)11, which serves as a movable member of the compressing mechanism10, is received in a lower portion of the middle housing29. A stationary scroll12of the compressing mechanism10, which serves as a stationary member, is securely held on a lower side of the movable scroll11. The movable scroll11is slidable relative to the stationary scroll12.

The movable scroll11and the stationary scroll12has a movable scroll base plate portion111and a stationary scroll base plate portion121, respectively, which are configured into a disk plate form. The movable scroll base plate portion111and the stationary scroll base plate portion121are opposed to each other in the top-to-bottom direction. A boss portion113, which is configured into a cylindrical tubular form and receives a lower end part of the drive shaft25, i.e., an eccentric portion253, is formed in a center portion of the movable scroll base plate portion111. The eccentric portion253is eccentric to a rotational center of the drive shaft25.

A rotation limiting mechanism (not shown) is provided in the movable scroll11and the stationary scroll12to limit rotation of the movable scroll11about the eccentric portion253. Therefore, when the drive shaft25is rotated, the movable scroll11revolves about a revolution center thereof, which is the rotational center of the drive shaft25, without rotating about the eccentric portion253. Two thrust plates13,14are stacked one after another in the top-to-bottom direction at a location between the movable scroll11and the middle housing29. The thrust plate13is positioned relative to the middle housing29by a positioning pin131. The thrust plate14is fixed to the movable scroll11and is positioned relative to the movable scroll11by a positioning pin141.

A spiral tooth (scroll wrap)112is formed in the movable scroll11to project from the movable scroll base plate portion111toward the stationary scroll12. A spiral tooth (a scroll wrap)122, which is meshed with the tooth112of the movable scroll11, is formed in a top surface (a movable scroll11side surface) of the stationary scroll base plate portion121. The spiral teeth112,122of the scrolls11,12are meshed with each other and contact with each other at a plurality of locations, so that a plurality of crescent shaped compression chambers15is formed. The refrigerant is supplied to each compression chamber15through a refrigerant inlet36and a refrigerant intake passage128. The refrigerant inlet36and the refrigerant intake passage128form a low pressure refrigerant supply passage37that conducts the refrigerant gas, which has a low pressure, to the compression chamber15. A refrigerant conduit38is connected to the refrigerant inlet36. The refrigerant intake passage128of the stationary scroll base plate portion121is communicated with a radially outermost part of a spiral groove of the stationary scroll base plate portion121(a radially outermost part of the groove formed between the tooth122and an outer peripheral part of the stationary scroll base plate portion121).

A discharge hole123is formed at a center part of the stationary scroll base plate portion121to discharge the refrigerant compressed in the compression chamber15. A discharge chamber124, which is communicated with the discharge hole123, is formed in the stationary scroll base plate portion121at a lower side of the discharge hole123. The discharge chamber124is defined by a recess125, which is formed in the lower surface of the stationary scroll12, and a partition member18, which is fixed to a lower surface of the stationary scroll12. A reed valve element17and a stopper19are placed in the discharge chamber124. The reed valve element17serves as a check valve that limits backflow of the refrigerant to the compression chamber15, and the stopper19limits a maximum opening degree of the reed valve element17. The refrigerant of the discharge chamber124is discharged to an outside of the housing30through the refrigerant discharge passage54, which is formed in the stationary scroll base plate portion121, and the refrigerant outlet54a(seeFIG. 1), which is formed in a tubular member31of the housing30.

As shown inFIG. 1, the refrigerant outlet54aof the housing30is connected to the refrigerant inlet47of the oil separator40through a refrigerant conduit48. The refrigerant, which enters the refrigerant inlet47of the oil separator40, is guided to a cylindrical space of the oil separator40and forms a swirl flow of the refrigerant in the cylindrical space. Thereby, the lubricant oil is separated from the refrigerant by a centrifugal force generated by the swirl flow of the refrigerant. The oil separator40has the function of separating the lubricant oil from the compressed refrigerant, which is discharged from the housing30, and the function of returning the separated lubricant oil to the housing30through the conduit connecting member34. The refrigerant gas, from which the lubricant oil is separated, is supplied to the heat exchanger2through a refrigerant conduit49.

A stationary side oil supply passage (not shown) is formed in an inside of the stationary scroll base plate portion121. A movable side oil supply passage (not shown) is formed in an inside of the movable scroll base plate portion111to intermittently communicate with the stationary side oil supply passage at the time of orbital movement (revolution) of the movable scroll11. The lubricant oil, which is outputted from the oil separator40, is supplied to a location between the stationary scroll base plate portion121and the movable scroll base plate portion111through the conduit connecting member34. Thereafter, this lubricant oil is supplied to a location between the eccentric portion253and the boss portion113of the movable scroll11and is also supplied to the bearings27,291and the like through the oil supply passage251. An oil reserve chamber35is formed in a bottom portion of the housing30.

The supply and discharge passages of the refrigerant, and the supply passage of the lubricant oil discussed above are indicated as examples and are not limited to the above-described ones. That is, the supply and discharge passages of the refrigerant and the supply passage of the lubricant oil may be changed to other known modifications. The compressor1ofFIG. 2is basically the same as the compressor recited in Patent Literature 4 except an injection mechanism (also referred to as an injection device) discussed later. Therefore, explanation of the compressor1will be partially omitted.

Next, the injection mechanism, which injects the intermediate pressure gas into the compression chamber of the compressor, will be described.FIG. 3(a)is a cross-sectional view showing an area around the compression chamber of the embodiment of the present disclosure.FIG. 3(b)is an enlarged front cross-sectional view of an area around the reed valve element.FIG. 3(c)is a plan view of the reed valve element.

In a case where the intermediate pressure gas is injected into the compression chamber of the compressor, particularly, when carbon dioxide is used as the refrigerant, it is demanded to have a high ratio of specific heat, a high gas density, a reduced dead volume and improvement of inflow of the gas in a high efficiency operational range. In the present embodiment, a plurality of injection ports (hereinafter simply referred to as ports)400, each of which injects the intermediate pressure refrigerant into the corresponding compression chamber15, is formed in the stationary scroll base plate portion121of the stationary scroll12. Each of the ports400and the surrounding portion thereof are constructed substantially identical to each other for all of the ports400. Therefore, in the following discussion, only one of the ports400will be described. Furthermore, instead of the plurality of ports400, it is possible to provide only one port400, which injects the intermediate pressure refrigerant to a corresponding one of the compression chambers15, if necessary. As shown inFIG. 3(b), the port400is radially offset from a valve seat passage304of a check valve300on an opposite side of the valve seat passage304, which is radially opposite from a connecting portion303aof the reed valve element303.

The refrigerant (the intermediate pressure gas) to be injected into the compression chamber15is guided from the branch point7ofFIG. 1into the interior of the compressor1through the intermediate pressure conduit8. The intermediate pressure conduit8is connected to a passage9, which is formed in the partition member18ofFIG. 2, and the intermediate pressure is supplied to the port400through the check valve300that is press fitted into a receiving hole310formed in the stationary scroll base plate portion121. The passage9and the receiving hole310and the port400provided in the stationary scroll base plate portion121form an intermediate pressure refrigerant supply passage80, which supplies the intermediate pressure gas (the refrigerant gas) having the intermediate pressure to the compression chamber15. The pressure of the intermediate pressure gas, which is supplied to the passage9through the intermediate pressure conduit8, is higher than the pressure (intake pressure) of the low pressure refrigerant drawn into the refrigerant inlet36of the compressor1and is lower than a pressure (discharge pressure) of the high pressure refrigerant discharged from the refrigerant outlet54aof the compressor1. Here, in a case where the intake pressure and the discharge pressure are defined as a first pressure and a second pressure, respectively, the pressure of the intermediate pressure gas is higher than the first pressure and is lower than the second pressure. The check valve300, which limits backflow of the refrigerant from the port400to the passage9, is placed between the passage9and the port400. The intermediate pressure gas is supplied to the compression chamber15through the check valve300and the port400in this order. A space between the compression chamber15and the check valve300becomes a dead volume. The presence of this volume may cause a re-expansion loss, so that it is desirable to minimize this volume.

FIGS. 3(a) to 3(c)show details of the check valve300. In the present embodiment, the check valve300is placed at the closest possible position to the compression chamber15. The receiving hole310is generally parallel to an extending direction of the port400and is recessed in a surface of the stationary scroll base plate portion121, which is located on a side that is opposite from the compression chamber15in a top-to-bottom direction (an axial direction of a central axis Od of the drive shaft25) inFIG. 3(a). In the present embodiment, the receiving hole310is formed as a circular hole that has a generally circular cross section. Furthermore, as shown inFIG. 2, the port400and the receiving hole310are formed in a limited area that is adjacent to the discharge chamber124. Therefore, the extending direction of the port400and the extending direction of the receiving hole310are tilted relative to the axial direction of the central axis Od of the drive shaft25. However, in a case where a sufficient area can be ensured immediately below the corresponding compression chamber15, the port400and the receiving hole310may be formed at the area immediately below the compression chamber15such that the extending direction of the port400and the extending direction of the receiving hole310are generally parallel to the axial direction of the central axis Od of the drive shaft25. The check valve300is press fitted into the receiving hole310and is located adjacent to a flow inlet400aof the port400. In this way, it is possible to shorten a length of the port400to reduce the dead volume. In order to minimize the dead volume of the port400up to the compression chamber15, it is normally preferable that the port400is a linear flow passage, which connects to the compression chamber15with a minimum distance.

The check valve300includes a valve seat portion (also referred to as a valve seat member)302and the reed valve element303. The valve seat portion302and the reed valve element303are formed as separate bodies, respectively, from metal (e.g., iron or iron alloy). At the time of assembling the check valve300to the receiving hole310, the reed valve element303is press fitted into the receiving hole310up to a point, at which a circular outer peripheral seal portion303cof the reed valve element303contacts a wall surface portion of the receiving hole310, i.e., a seat portion310bof the receiving hole310. Next, the valve seat portion302is press fitted into the receiving hole310and is fixed in a state where the valve seat portion302contacts the reed valve element303. In this way, the valve seat portion302is directly held in the state where the valve seat portion302contacts a valve seat portion holding section310aof the receiving hole310. The assembling method of the check valve300is not limited to this method, and the check valve300may be assembled by a different method. For example, a male thread may be formed in the outer peripheral surface of the valve seat portion302, and a female thread may be formed in an inner peripheral surface of the receiving hole310. In such a case, the male thread of the valve seat portion302is threadably engaged with the female thread of the receiving hole310, and the valve seat portion302is urged against the reed valve element303, which is inserted into the receiving hole310, to fix the valve seat portion302.

In the state shown inFIGS. 3(a) and 3(b)where the reed valve element303and the valve seat portion302are assembled into the receiving hole310, a space of the receiving hole310, which is located between the valve seat portion302and the flow inlet400aof the port400, forms a check valve chamber301that enables an opening operation and a closing operation of the reed valve element303. At the time of lifting the reed valve element303away from a valve seat302a, the check valve chamber301receives at least a portion (specifically, an opening and closing end portion303b) of the reed valve element303. In the present embodiment, a diameter of the check valve chamber301, which is measured in a direction that is perpendicular to a central axis O of the valve seat passage304, is set to be smaller than a diameter of the valve seat portion holding section310aof the receiving hole310. That is, a cross-sectional area of the check valve chamber301is set to be smaller than a cross-sectional area of the valve seat portion holding section310a. With this setting, the seat portion310b, to which the circular outer peripheral seat portion303cof the reed valve element303contacts at the time of press-fitting the reed valve element303into the receiving hole310, is formed in the inside of the receiving hole310. When the check valve300is configured into the circular form, it will be convenient at the time of assembling. The configuration of the check valve300is not limited to the circular form and may be changed to another form, which is other than the circular form. As shown inFIG. 3(c), the reed valve element303is made of a single-piece plate, in which the opening and closing end portion303bsurrounded by a C-shaped (arcuate) gap303dis formed in an inside of the circular outer peripheral seal portion303c. The opening and closing end portion303bis seatable against the annular valve seat302a, which surrounds the valve seat passage304that extends through the valve seat portion302in a plate thickness direction of the valve seat portion302, and the opening and closing end portion303bis connected to the circular outer peripheral seat portion303cthrough the connecting portion303a. The reed valve element303opens the valve seat passage304when the opening and closing end portion303band the connecting portion303a, which are adjacent to each other and are located within an extent indicated by a length A, are turned and lifted about a point, which is indicated by a reference sign B inFIG. 3(b)and serves as a rotational center, in the direction away from the valve seat302a, as indicated by a dotted line inFIG. 3(b). A reference sign d ofFIG. 3(b)indicates a lift amount of the reed valve element303(more specifically, the opening and closing end portion303b) at this time point.

Normally, in order to reduce the dead volume, the lift amount of the reed valve element303(more specifically, the opening and closing end portion303b) should be made as small as possible. However, when the refrigerant to be injected passes between the valve seat302aand the reed valve element303, the reed valve element303, which is adjacent to the valve seat302a, forms a flow passage resistance to possibly cause a reduction in the flow quantity. In the present embodiment, a central axis O2 of the valve seat portion302(more specifically, the valve seat302a) and a central axis O1 of the reed valve element303(the circular outer peripheral seal portion303c) are arranged such that the central axis O2 and the central axis O1 generally coincide with a central axis O3 of the check valve chamber301. A center Op of the flow inlet400aof the port400, which is communicated with the compression chamber15, is placed in a corresponding position, which is opposite from the connecting portion303aof the reed valve element303in the radial direction and is offset from the central axis O of the valve seat passage304. Therefore, when the opening and closing end portion303bof the reed valve element303is opened upon lifting of the opening and closing end portion303bfrom the valve seat302a, as indicated by the dotted line inFIG. 3(b), the refrigerant gas is outputted to the left side inFIG. 3(b)through a gap between the opening and closing end portion303band the valve seat302aand is inputted to the flow inlet400aof the port400. Thus, even when the lift amount d of the reed valve element303is made small, the flow passage resistance can be minimized. Particularly, the center Op of the flow inlet400aof the injection port400is overlapped with a corresponding portion of the gap303din a direction that is parallel to the central axis O of the valve seat passage304. This corresponding portion of the gap303dis placed on a side of the central axis O of the valve seat passage304that is opposite from the connecting portion303ain the radial direction of the reed valve element303. Specifically, it is required to place the center Op of the flow inlet400aof the port400in such a manner that the center Op of the flow inlet400ais overlapped with a portion of the gap303d, which is located in an area made of the second quadrant II and the third quadrant III in a case where the central axis O of the valve seat passage304ofFIG. 3(c)is defined as an origin, and a sign L ofFIG. 3(c)is defined as an X axis. In this way, it is possible to achieve the advantage of limiting the flow passage resistance discussed above.

Particularly, when the port400is placed on the opposite side, which is opposite from the connecting portion303aof the reed valve element303in the radial direction, the gap between the reed valve element303(more specifically, the opening and closing end portion303b) and the valve seat portion302(more specifically, the valve seat302a) at the time of opening the reed valve element303is maximized, and thereby the refrigerant can flow into the port400from the side where the flow passage cross-sectional area is maximized. Thus, the pressure loss can be limited.

With the above construction, the flow passage resistance is reduced, and the re-expansion loss caused by the dead volume is reduced. Thus, the performance ratio (flow characteristics) can be improved by about 25%. The injection of the intermediate pressure gas into the compression chamber15is made for the purpose of increasing the quantity of the flow through the condenser (the water refrigerant heat exchanger), and this increase in the quantity of the flow can be about 25%.

In the embodiment discussed above, the central axis O1 of the reed valve element303(more specifically, the circular outer peripheral seat portion303c), the central axis O2 of the valve seat portion302, and the central axis O3 of the check valve chamber301are arranged to be generally coaxial to each other. In this way, a generally circular outer peripheral edge of the circular outer peripheral seat portion303c, a generally circular outer peripheral edge of the valve seat portion302, and a generally circular inner peripheral edge of the check valve chamber301become generally concentric to each other and can be easily processed. Here, it should be noted that the present embodiment can be implemented even in a case where the central axis O of the valve seat passage304does not coincide with the central axes O1-O3 in some cases as long as the center Op of the flow inlet400aof the port400is offset from the central axis O of the valve seat passage304. In the present embodiment, the central axis O2 of the valve seat portion302and the central axis O of the valve seat passage304are separately indicated. Although these axes normally, generally coincide with each other, these axes are separately indicated in order to include the case, in which these axes do not coincide with each other, in the scope of the present disclosure.

An outer diameter of the circular outer peripheral seat portion303cof the reed valve element303is set to be slightly larger than an inner diameter of the receiving hole310, so that the positioning of the reed valve element303can be achieved by the press fitting without using, for example, a bolt(s). Specifically, the circular outer peripheral seat portion303cand the valve seat portion302can be fixed into the receiving hole310by the press fitting. In this way, the fixing element, such as the bolt(s), which was required in the prior art technique, is not required. Thereby, the costs can be reduced.

The present disclosure is not limited to the above embodiment, and the above embodiment can be appropriately modified within the scope of the present disclosure. For example, the above embodiment can be modified as follows.

FIG. 4(a)is a cross-sectional view of an area around the reed valve element in a first modification of the embodiment of the present disclosure.FIG. 4(b)is a cross-sectional view of the reed valve element. A first tapered outer peripheral edge portion T1 is formed in the circular outer peripheral seat portion303c, and a second tapered outer peripheral edge portion T2 is formed in the valve seat portion302. Specifically, the first tapered outer peripheral edge portion T1 is formed in the circular outer peripheral seat portion303c, and an outer diameter of the first tapered outer peripheral edge portion T1 progressively decreases in the axial direction of the central axis O of the valve seat passage304toward a side where the injection port400is located. Furthermore, the second tapered outer peripheral edge portion T2 is formed in an end part of the valve seat portion302, which is located adjacent to the circular outer peripheral seat portion303c, and an outer diameter of the second tapered outer peripheral edge portion T2 progressively decrease in the axial direction of the central axis O of the valve seat passage304toward the side where the injection port400is located. A radial inner end of the second tapered outer peripheral edge portion T2 contacts a corresponding part of the circular outer peripheral seat portion303c, which is located on a radially inner side of a radial inner end of the first tapered peripheral edge portion T1. That is, the radial inner end of the second tapered outer peripheral edge portion T2 contacts a planar surface303eof the circular outer peripheral seat portion303c. A tilt width (a radial extent) t2, in which the second tapered outer peripheral edge portion T2 is formed, in the radial direction of the valve seat portion302is made larger than a tilt width (a radial extent) t1, in which the first tapered outer peripheral edge portion T1 is formed, in the radial direction of the reed valve element303, so that the planar surface303eof the circular outer peripheral seat portion303ccontacts a planar surface302bof the valve seat portion302. As shown inFIG. 4(a), when the tilt width t2 of the valve seat side is made larger that the tilt width t1, the insertability and the holdability of the reed valve element303are ensured. In a case where the relationship between the tilt width t1 and the tilt width t2 is reversed from the above-discussed relationship, the reed valve element303may possibly be bent or damaged.

When the taper is formed in the circular outer peripheral seat portion303cof the reed valve element303, warping of the valve is increased to possibly deteriorate the sealing performance. Thus, as shown inFIG. 4(b), the required sealing performance is maintained by previously bending the connecting portion303a, at which the opening and closing end portion303bis connected to the circular outer peripheral seat portion303c, in an opposite direction that is opposite from the tapered portion. In this way, the required sealing performance of the reed valve element303is maintained. Furthermore, the assembling is eased, and the costs can be reduced.

FIG. 5(a)is a front cross-sectional view of an area around the reed valve element in a second modification of the embodiment of the present disclosure.FIG. 5(b)is a front cross-sectional view of the receiving hole310of the second modification.FIG. 5(c)is a plan view of the reed valve element of the second modification. In this modification, as shown inFIGS. 5(a) and 5(b), a sloped surface301c, which functions as a valve stopper at the valve opening time of the reed valve element303, is formed in a bottom surface301aof the check valve chamber301as a generally conical projecting surface that has an apex at a point P. As shown inFIG. 5(a), the opening and closing end portion303band the connecting portion303aof the reed valve element303include the point B, which serves as the rotational center of the opening and closing end portion303band the connecting portion303aat the time of lifting of the opening and closing end portion303band the connecting portion303aaway from the valve seat302a. An angle of the sloped surface301crelative to an imaginary plane H, which is perpendicular to the central axis O of the valve seat passage304, is preferably set to be Tan θ=0.05 to 1.0 (i.e., 0.05≦Tan θ≦1.0) and is more preferably set to be Tan θ=0.05 to 0.5 (i.e., 0.05≦Tan θ≦0.5) in conformity with the operational pattern of the valve. In this way, the bottom surface301aof the check valve chamber301forms the stopper, and thereby reduction of the number of the components and the implementation of the reliability of the reed valve can be ensured. Furthermore, the processing of the tapered configuration can be simultaneously performed at the time of processing the check valve chamber. Thus, in comparison to the prior art technique, which requires the separate processing, the costs can be reduced.

In the above embodiment and the modifications discussed above, the principle of the present disclosure is applied to the compressor of the scroll type. Alternatively, the principle of the present disclosure may be applied to another type of compressor (e.g., a compressor of a rotary type). At that time, the check valve300may be fixed by, for example, press fitting to a receiving hole that is formed in a stationary member (e.g., a cylinder of the compressor of the rotary type), which has a port communicated with a compression chamber.