COMPRESSOR

Abstract

A compressor includes fixed and movable side members. The fixed side member has a discharge port opened/closed by adischarge port. The discharge valve has a valve body which closes/opens an outlet end of the discharge port. An area of an inlet end of the discharge port is Ai, a peripheral length of the inlet end is Li, and a hydraulic diameter Di of the inlet end is 4(Ai/Li). A peripheral length of the outlet end of the discharge port is Lo, a reference lift amount of the valve body is ho, a cross sectional area Ao of an outlet side flow path formed between the outlet end of the discharge port and the valve body is Lo×ho, and a hydraulic diameter Do of the outlet side flow path is 4(Ao/2Lo). A ratio (Do/Di) is 0.25 or more and 0.5 or less.

Description

TECHNICAL FIELD

The present invention relates to compressors having a discharge valve.

BACKGROUND ART

Compressor having a discharge valve for opening/closing a discharge port have been known. For example, Patent Document 1 discloses a rotary compressor which has a so-called reed valve as a discharge valve. Patent Document 2 also discloses a discharge valve similar to the discharge valve in Patent Document 1.

In the rotary compressor of Patent Document 1, the discharge valve is provided at a main bearing. The discharge valve has a plate-like valve body provided so as to cover an outlet end of a discharge port. In the state in which the internal pressure of the compression chamber is lower than the back pressure of the valve body, the valve body closes the discharge port and prevents a hack-flow of a fluid into the compression chamber. On the other hand, in the state in which the internal pressure of the compression chamber is higher than the back pressure of the valve body, the valve body is elastically deformed and is separated from the outlet end of the discharge port. Thus, the high-pressure fluid in the compression chamber passes through the outlet end of the discharge port and the valve body, and flows out.

CITATION LIST

Patent Document

Patent Document 1: Japanese Unexamined Patent Publication No. 2008-101503

Patent Document 2: Japanese Unexamined Patent Publication No. 2002-070768

SUMMARY OF THE INVENTION

Technical Problem

To improve the efficiency of the compressor, it is preferable to reduce as much pressure loss as possible at a time when the fluid flows out from the discharge port, and it has been thought until recently that in order to reduce the pressure loss at the time when a fluid flows out from a discharge port, it is preferable to increase a gap between the lifted valve body and the outlet end of the discharge port as much as possible, and to do so, that it is necessary to increase a lift amount of the valve body of the discharge valve as much as possible.

On the contrary, the inventors of the present application found that once the lift amount of the valve body of the discharge valve exceeds a predetermined degree, the pressure loss at the time when a fluid flows out from the discharge port is not much reduced even if the lift amount is further increased. The reason why this happens is as follows. As will be explained in detail later, the greater the lift amount of the valve body of the discharge valve is, the larger a vortex formed around the outlet end of the discharge port becomes. The vortex interrupts a flow of the fluid passing through the gap between the outlet end of the discharge port and the valve body. Thus, once the lift amount of the valve body of the discharge valve reaches and exceeds a predetermined degree, the pressure loss at the time when a fluid flows out from the discharge port is not much reduced even if the lift amount of the valve body is further increased, because of an increase in the effects of the vortex.

The present invention is thus intended to improve the efficiency of a compressor by appropriately setting a lift amount of a valve body of a discharge valve.

Solution to the Problem

The first aspect of the present invention is directed to a compressor having a fixed side member (45) which forms a compression chamber (36) and a movable side member (38) which is rotated and changes a volume of the compression chamber (36), the compressor configured to suck a fluid into the compression chamber (36) and compress the fluid. The fixed side member (45) is provided with a discharge port (50) that penetrates the fixed side member (45) and leads the fluid out of the compression chamber (36), and a discharge valve (60) that opens/closes the discharge port (50), the discharge valve (60) has a valve body (61) which closes the discharge port (50) by covering an outlet end (52) of the discharge port (50) and opens the discharge port (50) by being lifted from the outlet end (52) of the discharge port (50), an area of an inlet end (51) of the discharge port (50) is Ai; a peripheral length of the inlet end (51) is Li; and a hydraulic diameter of the inlet end (51) is defined by Di=4(Ai/Li), a peripheral length of the outlet end (52) of the discharge port (50) is Lo; a reference lift amount of the valve body (61) is ho; a cross sectional area of an outlet side flow path (70) formed between the outlet end (52) of the discharge port (50) and the valve body (61) is defined by Ao=Lo×ho; and a hydraulic diameter of the outlet side flow path (70) is defined by Do=4(Ao/2Lo), and a ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.5 or less.

In the first aspect of the present invention, a discharge port (50) is formed in the fixed side member (45) of the compressor (10). The inlet end (51) of the discharge port (50) communicates with the compression chamber (36). The outlet end (52) of the discharge port (50) is opened/closed by the valve body (61) of the discharge valve (60). In the state in which the valve body (61) of the discharge valve (60) covers the outlet end (52) of the discharge port (50), a back-flow of a fluid from outside the fixed side member (45) into the discharge port (50) is prevented by the valve body (61). In the state in which the valve body (61) of the discharge valve (60) is lifted from the outlet end (52) of the discharge port (50), the fluid in the compression chamber (36) flows outside the fixed side member (45) through a gap between the outlet end (52) of the discharge port (50) and the valve body (61).

The peripheral length Li of the inlet end (51) of the discharge port (50) is a wetted perimeter length of the inlet end (51) of the discharge port (50). Thus, the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is expressed by the following Equation 01:

Di=4(Ai/Li)   (Equation 01)

In the state in which the valve body (61) of the discharge valve (60) is lifted from the outlet end (52) of the discharge port (50), and the outlet end (52) of the discharge port (50) and the valve body (61) are parallel to each other, the distance between the outlet end (52) of the discharge port (50) and the valve body (61) (that is, a lift amount of the valve body (61)) is uniform around the entire outlet end (52) of the discharge port (50). Thus, the cross sectional area Ao of the outlet side flow path (70) formed between the outlet end (52) of the discharge port (50) and the valve body (61) is equal to a surface area (i.e., Lo×h) of a cylinder having a peripheral length equal to the peripheral length Lo of the outlet end (52) of the discharge port (50), and a height equal to the lift amount h of the valve body (61). However, in the case, for example, where the discharge valve (60) is a reed valve, the valve body (61) is tilted with respect to the outlet end (52) of the discharge port (50), and therefore the distance between the outlet end (52) of the discharge port (50) and the valve body (61) is not uniform around the outlet end (52) of the discharge port (50). To make it possible, even in such a case, to calculate the cross sectional area Ao of the outlet side flow path (70) similarly to the case where the lift amount of the valve body (61) is uniform around the entire outlet end (52) of the discharge port (50), a typical value of the distance between portions of the outlet end (52) of the discharge port (50) and the valve body (61) is used as a reference lift amount ho. Thus, the cross sectional area Ao of the outlet side flow path (70) is expressed by the following Equation 02:

Ao=Lo×ho   (Equation 02)

In the case where the valve body (61) is parallel to the outlet end (52) of the discharge port (50), the wetted perimeter length of the outlet side flow path (70) formed between the outlet end (52) of the discharge port (50) and the valve body (61) is twice the peripheral length Lo of the outlet end (52) of the discharge port (50). By using the reference lift amount ho, the case in which the valve body (61) is tilted with respect to the outlet end (52) of the discharge port (50) can be treated similarly to the case in which the valve body (61) is parallel to the outlet end (52) of the discharge port (50). Thus, even in the case where the valve body (61) is tilted with respect to the outlet end (52) of the discharge port (50), the wetted perimeter length of the outlet side flow path (70) can be approximately 2Lo. Thus, 115 the hydraulic diameter Do of the outlet side flow path (70) is expressed by the following Equation 03:

Do=4(Ao/2Lo)=2ho   (Equation 03)

In the first aspect of the present invention, a ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.5 or less (Do/Di<0.5). As shown in Equation 03, the hydraulic diameter Do of the outlet side flow path (70) is twice the reference lift amount ho. Thus, in the present invention, the reference lift amount ho of the valve body (61) of the discharge valve (60) is set to a value according to the hydraulic diameter Di of the inlet end (51) of the discharge port (50).

The second aspect of the present invention is that in the first aspect of the present invention, the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.4 or less.

In the second aspect of the present invention, the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.4 or less (Do/Di<0.4). In the present invention, similarly to the first aspect of the present invention, the reference lift amount ho of the valve body (61) of the discharge valve (60) is set to a value according to the hydraulic diameter Di of the inlet end (51) of the discharge port (50).

The third aspect of the present invention is that in the first or second aspect of the present invention, the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.25 or more.

In the third aspect of the present invention, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the ratio (Do/Di) of the “hydraulic diameter Do=4(Ao/2Lo)=2ho of the outlet side flow path (70)” to the “hydraulic diameter Di=4(Ai/Li) of the inlet end (51) of the discharge port (50)” is 0.25 or more and 0.5 or less (0.25≦Do/Di≦0.5) or 0.25 or more and 0.4 or less (0.25≦Do/Di≦0.4).

The fourth aspect of the present invention is that in any one of the first to third aspects of the present invention, the fixed side member (45) is provided with a chamfered portion (56) along the entire periphery of the outlet end (52) of the discharge port (50).

In the fourth aspect of the present invention, the chamfered portion (56) of the fixed side member (45) is provided along the entire periphery of the outlet end (52) of the discharge port (50). Thus, the cross sectional area of the flow path of the discharge port (50) closer to the outlet end (52) is gradually increased toward the outlet end (52) of the discharge port (50). In the case where the fixed side member (45) is provided with the chamfered portion (56), the area of the outlet end (52) of the discharge port (50) is larger than in the case where the chamfered portion (56) is not provided. The area of the outlet end (52) of the discharge port (50) is equal to an area (i.e., a pressure receiving area) of the valve body (61) covering the outlet end (52) of the discharge port (50) to which pressure is applied from the discharge port (50). Thus, if the area of the outlet end (52) of the discharge port (50) is increased, it means that the pressure receiving area of the valve body (61) is increased, and the force in a direction separating the valve body (61) from the outlet end (52) of the discharge port (50) is increased.

The fifth aspect of the present invention is that in the fourth aspect of the present invention, a height H of the chamfered portion (56) in an axial direction of the discharge port (50) and a width W of the chamfered portion (56) in a direction orthogonal to the axial direction of the discharge port (50) satisfy a relationship of 0<H/W<0.5.

The larger the width W of the chamfered portion (56) is, the larger the pressure receiving area of the valve body (61) covering the outlet end (52) of the discharge port (50) is. On the other hand, the lower the height H of the chamfered portion (56) is, the smaller the amount of increase in volume of the discharge port (50) caused by the provision of the chamfered portion (56) is. The volume of the discharge port (50) is a dead volume which is not changed even if the movable side member (38) rotates. Thus, to improve the efficiency of the compressor (10), a smaller volume of the discharge port (50) is preferable.

In the fifth aspect of the present invention, the chamfered portion (56) formed on the fixed side member (45) has such a shape of which the height H and the width W satisfy the relationship 0<H/W<0.5. That is, the height H of the chamfered portion (56) is less than half the width W of the chamfered portion (56). Thus, it is possible to reduce an amount of increase in volume of the discharge port (50), while increasing the pressure receiving area of the valve body (61) covering the outlet end (52) of the discharge port (50).

The sixth aspect of the present invention is that in any one of the first to fifth aspects of the present invention, a cross sectional shape of the discharge port (50) is an oblong or an ellipse.

In the sixth aspect of the present invention, a discharge port (50) whose cross sectional shape is an oblong or an ellipse is formed in the fixed side member (45).

Advantages of the Invention

In the compressor (10) of the present invention, the reference lift amount ho of the valve body (61) of the discharge valve (60) is set such that the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.5 or less. By setting the lift amount of the valve body (61) to such a value, the reference lift amount ho of the valve body (61) becomes a relatively small value, and a vortex generated at the time when a fluid passes between the outlet end (52) of the discharge port (50) and the valve body (61) is downsized. Thus, in the present invention, the pressure loss of the fluid at the time when the fluid flows out from the discharge port (50) can be reduced, and the efficiency of the compressor (10) can be improved.

If the discharge valve (60) is not closed at an appropriate timing, the fluid discharged from the compression chamber (36) through the discharge port (50) may flow back to the discharge port (50). On the other hand, if the lift amount of the valve body (61) of the discharge valve (60) is increased, it takes longer time for the valve body (61) to travel, and the timing at which the valve body (61) closes the outlet end (52) of the discharge port (50) may be delayed from the appropriate timing. If the valve body (61) delays in closing the outlet end (52) of the discharge port (50), the amount of fluid flowing back to the compression chamber (36) from outside the fixed side member (45) is increased and the efficiency of the compressor (10) is reduced.

In contrast, in the present invention, the timing at which the valve body (61) closes the outlet end (52) of the discharge port (50) is determined such that the reference lift amount ho of the valve body (61) is relatively small. Thus, the delay of timing at which the valve body (61) closes the outlet end (52) of the discharge port (50) can be reduced, and the amount of fluid flowing back to the compression chamber (36) from outside the fixed side member (45) can be reduced. As a result, in view of this point, as well, the efficiency of the compressor (10) can be improved in the present invention.

In particular, in the second aspect of the present invention, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is 0.4 or less. Thus, the delay in timing at which the valve body (61) closes the outlet end (52) of the discharge port (50) can be further reduced. Accordingly, in the present invention, the amount of fluid flowing back to the compression chamber (36) from outside the fixed side member (45) can be further reduced, and as a result, the efficiency of the compressor (10) can be further improved.

To avoid the back-flow of the fluid to the compression chamber (36), it is only necessary that the outlet end (52) of the discharge port (50) is closed by the valve body (61) of the discharge valve (60) at an appropriate timing. Thus, if the lift amount of the valve body (61) of the discharge valve (60) is equal to or smaller than a certain degree, further reduction in the lift amount of the valve body (61) does not contribute to an efficiency improvement of the compressor (10).

In contrast, in the third aspect of the present invention, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the ratio (Do/Di) of the “hydraulic diameter Do of the outlet side flow path (70)” to the “hydraulic diameter Di of the inlet end (51) of the discharge port (50)” is 0.25 or more and 0.5 or less (0.25≦Do/Di≦0.5) or 0.25 or more and 0.4 or less (0.25≦Do/Di≦0.4). Thus, in the present invention, the reference lift amount ho of the valve body (61) can be set in a range where the amount of fluid flowing back to the compression chamber (36) can be reduced.

In the fourth aspect of the present invention, the chamfered portion (56) around the entire periphery of the outlet end (52) of the discharge port (50) is formed on the fixed side member (45). Thus, the area of the outlet end (52) of the discharge port (50) is increased, compared to the case in which the chamfered portion (56) is not formed on the fixed side member (45). As a result, it is possible to increase the pressure receiving area of the valve body (61) covering the outlet end (52) of the discharge port (50), and possible to increase the force in a direction separating the valve body (61) from the outlet end (52) of the discharge port (50). Thus, a difference between the internal pressure of the compression chamber (36) and the back pressure of the valve body (61) at a moment when the valve body (61) begins to separate from the outlet end (52) of the discharge port (50) can be reduced, thereby reducing overcompression, i.e., compression of the fluid in the compression chamber (36) more than necessary, and improving the efficiency of the compressor (10).

The chamfered portion (56) of the fifth aspect of the present invention has such a shape of which the height H and the width W satisfy the relationship 0<H/W<0.5. Thus, it is possible to reduce an amount of increase in volume of the discharge port (50), while maintaining the pressure receiving area of the valve body (61) covering the outlet end (52) of the discharge port (50).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross section of a compressor of an embodiment.

FIG. 2 is a cross section of a compressor mechanism taken along the line A-A of FIG. 1.

FIG. 3 shows cross sections of a main part of the compressor mechanism along the longer diameter of a discharge port. FIG. 3A illustrates the state in which a discharge valve is closed, and FIG. 3B illustrates the state in which the discharge valve is open.

FIG. 4 is a cross section of a main part of the compressor mechanism along the shorter diameter of the discharge port.

FIG. 5 is a cross section of the compressor mechanism, illustrating the enlarged main part of the FIG. 3B.

FIG. 6 is a plan view of a front head, and illustrates a portion of the front head near an outlet end of the discharge port.

FIG. 7A is an oblique view illustrating the shape of actual outlet side flow path, and FIG. 7B is an oblique view illustrating the shape of a virtual outlet side flow path.

FIG. 8 is a table showing hydraulic diameter rate Do/Di, etc. about a plurality of reference lift amounts ho.

FIG. 9 shows cross sections of a main part of the front head, illustrating a flow of a gas refrigerant flowing out from the discharge port. FIG. 9A illustrates a cross section taken along the line B-B of FIG. 4 and a cross section taken along the line C-C of FIG. 3, in the case where the reference lift amount ho=1.6 mm. FIG. 9B illustrates a cross section taken along the line B-B of FIG. 4 and a cross section taken along the line C-C of FIG. 3, in the case where the reference lift amount ho=0.8 mm.

FIG. 10 shows graphs of simulation results in the case where the reference lift amount ho=1.4 mm and the case where the reference lift amount ho=1.6 mm. FIG. 10A shows changes between the pressure in the compression chamber and the lift amount of the valve body while a drive shaft makes one rotation. FIG. 10B shows changes in a flow rate of a refrigerant discharged from the discharge port while the drive shaft makes one rotation.

FIG. 11 shows graphs of simulation results in the case where the reference lift amount ho=1.2 mm and the case where the reference lift amount ho=1.6 mm. FIG. 11A shows changes between the pressure in the compression chamber and the lift amount of the valve body while the drive shaft makes one rotation. FIG. 11B shows changes in a flow rate of a refrigerant discharged from the discharge port while the drive shaft makes one rotation.

FIG. 12 shows graphs of simulation results in the case where the reference lift amount ho=1.0 mm and the case where the reference lift amount ho=1.6 mm. FIG. 12A shows changes between the pressure in the compression chamber and the lift amount of the valve body while a drive shaft makes one rotation. FIG. 12B shows changes in a flow rate of a refrigerant discharged from the discharge port while the drive shaft makes one rotation.

FIG. 13 shows graphs of simulation results in the case where the reference lift amount ho=0.8 mm and the case where the reference lift amount ho=1.6 mm. FIG. 13A shows changes between the pressure in the compression chamber and the lift amount of the valve body while the drive shaft makes one rotation. FIG. 13B shows changes in a flow rate of a refrigerant discharged from the discharge port while the drive shaft makes one rotation.

FIG. 14 is a graph showing a relationship between the hydraulic diameter rate Do/Di and a back-flow amount of the refrigerant into the compression chamber.

FIG. 15 shows cross sections of the front head, illustrating the shape of the discharge port of the third variation of the embodiment. FIG. 15A illustrates a cross section corresponding to the B-B cross section of FIG. 4. FIG. 15B illustrates a cross section corresponding to the C-C cross section of FIG. 3.

FIG. 16 shows cross sections of the front head, illustrating the shape of the discharge port of the fourth variation of the embodiment. FIG. 16A illustrates a cross section corresponding to the B-B cross section of FIG. 4. FIG. 16B illustrates a cross section corresponding to the C-C cross section of FIG. 3.

FIG. 17 is a plan view of a front head of the fifth variation of the embodiment, and illustrates a portion of the front head near an outlet end of the discharge port.

FIG. 18 is a cross section of a compressor mechanism of the sixth variation of the embodiment, and illustrates a cross section corresponding to FIG. 2.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail based on the drawings. The following embodiments and variations are merely preferred examples in nature, and are not intended to limit the scope, applications, and use of the invention,

A compressor (10) of the present embodiment is provided in a refrigerant circuit which performs a vapor compression refrigeration cycle, and the compressor (10) suctions a refrigerant evaporated in an evaporator and compresses the refrigerant.

—General Structure of Compressor—

As shown in FIG. 1, the compressor (10) of the present embodiment s a hermetic compressor which accommodates, in a casing (11), a compressor mechanism (30) and an electric motor (20).

The casing (11) is a cylindrical closed container, standing upright. The casing (11) has a cylindrical barrel (12) and a pair of end plates (13, 14) which close the both ends of the barrel (12). A suction pipe (15) is attached to a lower portion of the barrel (12). A discharge pipe (16) is attached to the upper end plate (13).

The electric motor (20) is positioned above the compressor mechanism (30). The electric motor (20) has a stator (21) and a rotor (22). The stator (21) is fixed to the barrel (12) of the casing (11). The rotor (22) is attached to a drive shaft (23) of the compressor mechanism (30), described later.

The compressor mechanism (30) is positioned at a lower portion in the casing (11). The compressor mechanism (30) is a so-called oscillating piston type rotary fluid machine. The compressor mechanism (30) has a front head (31), a cylinder (32), and a rear head (33).

The cylinder (32) is a disk-shaped thick member (see FIG. 2). A circular hole which forms a compression chamber (36) together with a piston (38), described later, is formed at a central portion of the cylinder (32). The front head (31) is a plate-like member which closes the upper end surface of the cylinder (32). A main bearing (31a) which supports the drive shaft (23) is arranged to project from a central portion of the front head (31). The rear head (33) is a plate-like member which closes the lower end surface of the cylinder (32). An auxiliary bearing (33a) which supports the drive shaft (23) is arranged to project from a central portion of the rear head (33).

The cylinder (32) is fixed to the barrel (12) of the casing (11). The front head (31), the cylinder (32), and the rear head (33) are fastened together with bolts, and form a fixed side member (45).

The compressor mechanism (30) has a drive shaft (23). The drive shaft (23) has a main shaft (24) and an eccentric portion (25). The eccentric portion (25) is positioned at a lower portion of the main shaft (24). The eccentric portion (25) is in a columnar shape with a diameter larger than the diameter of the main shaft (24), and is eccentric with respect to the main shaft (24). Although not shown, an oil supply path is formed in the drive shaft (23). The lubricating oil accumulated in the bottom of the casing (11) is supplied to sliding portions of the bearings (31a, 33a) and the compressor mechanism (30) through the oil supply path.

As also shown in FIG. 2, the compressor mechanism (30) has a piston (38) as a movable side member and a blade (43).

The piston (38) is in a slightly thick cylindrical shape. The eccentric portion (25) of the drive shaft (23) is rotatably fitted in the piston (38). An outer circumferential surface (39) of the piston (38) slides on an inner circumferential surface (35) of the cylinder (32). In the compressor mechanism (30), the compression chamber (36) is formed between the outer circumferential surface (39) of the piston (38) and the inner circumferential surface (35) of the cylinder (32).

The blade (43) is a flat plate-like member projecting from the outer circumferential surface (39) of the piston (38), and is integrally formed with the piston (38). The blade (43) separates the compression chamber (36) into a high-pressure chamber (36a) and a low-pressure chamber (36b).

The compressor mechanism (30) has a pair of bushes (41). The pair of bushes (41) are fitted in a bush groove (40) of the cylinder (32), and sandwich the blade (43) from both sides. The blade (43) integrally formed with the piston (38) is supported on the cylinder (32) via the bushes (41).

The cylinder (32) is provided with a suction port (42) that penetrates the cylinder (32) in the radius direction. The suction port (42) communicates with the low-pressure chamber (36b) of the compression chamber (36). One end of the suction port (42) is open on the inner circumferential surface (35) of the cylinder (32). The open end of the suction port (42) which is open on the inner circumferential surface (35) is located near the bushes (41) (on the right side of the bushes (41) in FIG. 2). On the other hand, the suction pipe (15) is inserted in the other end of the suction port (42).

A discharge port (50) is formed in the front head (31). The discharge port (50) is a through hole which penetrates the front head (31) in the thickness direction of the front head (31) (see FIG. 1). The discharge port (50) communicates with the high-pressure chamber (36a) of the compression chamber (36). The open end of the discharge port (50) which is open on the lower surface of the front head (31) is located opposite to the suction port (42) with respect to the bushes (41) (on the left side of the bushes (41) in FIG. 2). The shape of the discharge port (50) will be described in detail later.

The front head (31) is provided with a discharge valve (60), which is a reed valve. As shown in FIG. 3, the discharge valve (60) is attached to the upper surface of the front head (31). The discharge valve (60) has a valve body (61), a valve guard (62), and a securing pin (63).

The valve body (61) is an elongated, thin fiat plate-like member. A material for the valve body (61) is spring steel, for example. The valve body (61) is provided such that its end portion covers an outlet end (52) of the discharge port (50). When the discharge valve (60) is in a dosed state, a front surface (61a) of the valve body (61) is brought into tight contact with a periphery (52a) of the outlet end (52) of the discharge port (50). The valve guard (62) is a slightly thick metallic member with a high stiffness. The valve guard (62) is in an elongated plate-like shape corresponding to the shape of the valve body (61). Further, an end portion of the valve guard (62) is slightly curved upward. The valve guard (62) is arranged to overlap the valve body (61). The proximal portion of the valve guard (62) and the proximal portion of the valve body (61) are fixed to the front head (31) with the securing pin (63).

As shown in FIG. 3A, the discharge port (50) is closed in the state in which the valve body (61) covers the outlet end (52) of the discharge port (50). On the other hand, as shown in FIG. 3B and FIG. 4, the discharge port (50) is open in the state in which the valve body (61) is lifted from the outlet end (52) of the discharge port (50).

As described above, the compressor mechanism (30) of the present embodiment is a rotary fluid machine which has the cylinder (32), the front head (31) and the rear head (33) which serve as closing members for closing end portions of the cylinder (32), the piston (38) which is accommodated in the cylinder (32) and eccentrically rotates, and the blade (43) which separates the compression chamber (36) formed between the cylinder (32) and the piston (38) into a low-pressure side and a high-pressure side.

—Operation of Compressor—

Operation of the compressor (10) will be described with reference to FIG. 2.

When the electric motor (20) is turned on, the drive shaft (23) rotates in a clockwise direction in FIG. 2. When the drive shaft (23) rotates, the piston (38) integrally formed with the blade (43) oscillates and eccentrically rotates. When the piston (38) moves, a low-pressure gas refrigerant is suctioned into the low-pressure chamber (36b) of the compression chamber (36) through the suction port (42), and at the same time, a gas refrigerant that is present in the high-pressure chamber (36a) of the compression chamber (36) is compressed.

At this moment, gas pressure (pressure in the dome) in the internal space of the casing (11) is applied to a back surface (61b) of the valve body (61) of the discharge valve (60). Thus, as long as the gas pressure in the high-pressure chamber (36a) is lower than the pressure in the dome, the discharge valve (60) is in the closed state as shown in FIG. 3A. When the piston (38) moves, and the gas pressure in the high-pressure chamber (36a) gradually increases and exceeds the pressure in the dome, the end portion of the valve body (61) of the discharge valve (60) separates from the outlet end (52) of the discharge port (50). As a result, the discharge valve (60) is open as shown in FIG. 3B.

When the discharge valve (60) is open, the as refrigerant in the high-pressure chamber (36a) passes through the discharge port (50) and flows between the outlet end (52) of the discharge port (50) and the valve body (61), and is discharged to the internal space of the casing (11) (that is, outside the compressor mechanism (30)). The high-pressure gas refrigerant discharged from the compressor mechanism (30) passes through the discharge pipe (16) and is led outside the casing (11).

—Shape of Discharge Port—

The shape of the discharge port (50) will be described in detail with reference to FIG. 5 and FIG. 6.

The discharge port (50) is a straight through hole which penetrates the front head (31) in the plate thickness direction (see FIG. 5). An inlet end (51) of the discharge port (50) is open on the front surface (i.e., the surface facing the cylinder (32)) of the front head (31). On the other hand, the outlet end (52) of the discharge port (50) is open on the back surface (i.e., the surface opposite to the surface facing the cylinder (32)) of the front head (31). On the back surface of the front head (31), a portion around the outlet end (52) of the discharge port (50) is raised from its surrounding area, and serves as a seat portion (55).

The cross section of the flow path of the discharge port (50) (i.e., the cross section orthogonal to the axial direction of the discharge port (50)) is in an oblong shape (see FIG. 6). The discharge port (50) is arranged such that its shorter diameter is along the radius dimension of the inner circumferential surface (35) of the cylinder (32) (see FIG. 2).

The front head (31) is provided with a chamfered portion (56) along the periphery (52a) of the outlet end (52) of the discharge port (50). The chamfered portion (56) is formed around the entire periphery of the outlet end (52) of the discharge port (50) (see FIG. 6). The chamfered portion (56) is formed such that the height H in the axial direction of the discharge port (50) and the width W in a direction orthogonal to the axial direction of the discharge port (50) are respectively uniform around the entire periphery of the chamfered portion (56) (see FIG. 5). In the present embodiment, the height H and the width W of the chamfered portion (56) satisfy the following formula: 0<H/W<0.5. That is, the height H of the chamfered portion (56) is less than half of the width W of the chamfered portion (56) (0<H<W/2).

A portion of the discharge port (50) at a position lower than the chamfered portion (56) forms a main pass (53). The cross section of the flow path of the main pass (53) is in an oblong shape having an arc portion with a curvature radius Ri and a straight portion with a length Ls. Further, the shape of the cross section of the flow path of the main pass (53) is uniform along the entire length thereof. That is, the longer diameter length D₁ and the shorter diameter length D₂ of the cross section of the flow path of the main pass (53) are respectively uniform along the entire length of the main pass (53). Accordingly, the shape of the inlet end (51) of the discharge port (50) is also in an oblong shape having an arc portion with the curvature radius Ri and a straight portion with the length Ls.

The shape of the outlet end (52) of the discharge port (50) is in an oblong shape slightly larger than that of the inlet end (51) of the discharge port (50). Specifically, the shape of the outlet end (52) of the discharge port (50) is in an oblong shape having an arc portion with a curvature radius defined by Ro=Ri+W and a straight portion with a length Ls.

At the inlet end (51) of the discharge port (50) of the present embodiment, the curvature radius of the arc portion is defined by Ri=2.1 mm, and the length of the straight portion is defined by Ls=5.3 mm. At the outlet end (52) of the discharge port (50), the curvature radius of the arc portion is defined by Ro=3.1 mm, and the length of the straight portion is defined by Ls=5.3 mm. At the chamfered portion (56) of the discharge port (50), a ratio of the height H to the width W (H/W) is 0.5 (H/W=0.5). The figures shown herein are merely an example.

If the front head (31) is provided with the chamfered portion (56), an area of the outlet end (52) of the discharge port (50) is larger than in the case in which the front head (31) is not provided with the chamfered portion (56). The area of the outlet end (52) of the discharge port (50) is equal to an area (i.e., a pressure receiving area) of a portion of the front surface (61a) of the valve body (61) to which pressure is applied from the e discharge port (50). Thus, if the area of the outlet end (52) of the discharge port (50) is increased, it means that the pressure receiving area of the valve body (61) is increased, and the force in a direction separating the valve body (61) from the outlet end (52) of the discharge port (50) is increased.

If the force in the direction separating the valve body (61) from the outlet end (52) of the discharge port (50) is increased, a difference between the “gas pressure in the compression chamber (36)” and the “gas pressure applied to the back surface (61b) of the valve body (61)” at a moment when the valve body (61) begins to separate from the outlet end (52) of the discharge port (50) becomes small. Thus, loss (i.e., loss by overcompression) caused by compressing the gas refrigerant in the compression chamber (36) more than necessary is reduced.

On the other hand, on condition that the width W of the chamfered portion (56) is the same, the lower the height H of the chamfered portion (56) is, the smaller the amount of increase in volume of the discharge port (50) due to the provision of the chamfered portion (56) is. The volume of the discharge port (50) is a dead volume which is not changed even if the piston (38) rotates. Thus, to improve the efficiency of the compressor (10), it is preferable to reduce the volume of the discharge port (50) as much as possible.

Thus, in the compressor (10) of the present embodiment, the height H of the chamfered portion (56) is set to less than half of the width W of the chamfered portion (56), considering an efficiency improvement caused by a reduction of the loss by overcompression, and an efficiency decrease caused by an increase of the dead volume.

—Lift Amount of Valve Body of Discharge Valve—

In the compressor (10) of the present embodiment, a lift amount of the valve body (61) of the discharge valve (60) is determined such that pressure loss of the gas refrigerant at the time when the gas refrigerant is discharged from the compressor mechanism (30) can be reduced to low level, and such that a reduction in efficiency of the compressor (10) due to delay in closing the valve body (61) of the discharge valve (60) can be reduced. As will be described in detail later, in the compressor (10) of the present embodiment, a reference lift amount ho of the valve body (61) of the discharge valve (60) is determined, based on a hydraulic diameter Di of the inlet end (51) of the discharge port (50).

<Hydraulic Diameter Di of Inlet End of Discharge Port>

As described above, the inlet end (51) of the discharge port (50) is in an oblong shape having the arc portion with the curvature radius Ri and the straight portion with the length Ls. Thus, the length (i.e., the peripheral length of the periphery (51a) of the inlet end (51) of the discharge port (50) is expressed by Equation 1 shown below, and the area Ai thereof is expressed by Equation 2 shown below. The peripheral length Li of the inlet end (51) of the discharge port (50) is a wetted perimeter length of the inlet end (51) of the discharge port (50). Thus, the hydraulic diameter Di of the inlet end (51) of the discharge port (50) is expressed by Equation 3 below. Equation 3 is the same as Equation 01 described above.

Li=2πRi+2Ls   (Equation 1)

Ai=πRi ²+2Ri·Ls   (Equation 2)

Di=4(Ai/Li)   (Equation 3)

The inlet end (51) of the discharge port (50) of the present embodiment has the arc portion with the curvature radius Ri of 2.1 mm, and the straight portion with the length Ls of 5.3 mm. Thus, the peripheral length Li is 23.8 mm; the area Al is 36.1 mm²; and the hydraulic diameter Di is 6.1 mm.

<Reference Lift Amount ho of Valve Body of Discharge Valve>

As shown in FIG. 5, the reference lift amount ho of the valve body (61) of the discharge valve (60) is the maximum lift amount of the valve body (61) on a center line CL of the discharge port (50). That is, the reference lift amount ho is a distance from the “outlet end (52) of the discharge port (50)” to the “front surface (61a) of the valve body (61)” on the center line CL of the discharge port (50) in the state in which the entire back surface (61b) of the valve body (61) touches the valve guard (62).

The center line CL of the discharge port (50) is a straight line passing an intersection point of the longer diameter and the shorter diameter of the inlet end (51) of the discharge port (50) and an intersection point of the longer diameter and the shorter diameter of the outlet end (52) of the discharge port (50). The center line CL is orthogonal to the inlet end (51) and the outlet end (52) of the discharge port (50).

The front surface (61a) of the valve body (61) is tilted with respect to the outlet end (52) of the discharge port (50) in the state in which the entire back surface (61b) of the valve body (61) touches the valve guard (62). Thus, as shown in FIG. 5, the distance (that is, the lift amount of the valve body (61)) from the outlet end (52) of the discharge port (50) to the front surface (61a) of the valve body (61) has a maximum value of h₁, and a minimum value of h₂.

<Hydraulic Diameter Do of Outlet Side Flow Path>

In the state in which the valve body (61) of the discharge valve (60) is lifted from the outlet end (52) of the discharge port (50), an outlet side flow path (70) is formed between the outlet end (52) of the discharge port (50) and the valve body (61). The gas refrigerant discharged from the discharge port (50) passes through the outlet side flow path (70).

As described above, the outlet end (52) of the discharge port (50) is in an oblong shape. Further, as shown in FIG. 5, in the state in which the valve body (61) is lifted from the outlet end (52) of the discharge port (50), the front surface (61a) of the valve body (61) is tilted with respect to the outlet end (52) of the discharge port (50). Thus, the outlet side flow path (70) has a cross-sectional shape as shown in FIG. 7A (that is, the same shape as a side surface of a tubular object having a top surface tilted with respect to its bottom surface. A lower periphery (72) of the outlet side flow path (70) is in the same oblong shape as the periphery (52a) of the outlet end (52) of the discharge port (50). On the other hand, an upper periphery (71) of the outlet side flow path (70) is in the shape obtained by projecting the periphery (52a) of the outlet end (52) of the discharge port (50) to the front surface (61a) of the valve body (61). Further, the height of the outlet side flow path (70) has a maximum value of h₁, and a minimum value of h₂.

The front surface (61a) of the valve body (61) is not curved and is substantially flat in the state in which the entire back surface (61b) of the valve body (61) touches the valve guard (62). Thus, the reference lift amount ho of the valve body (61) is substantially equal to an average value ((h₁+h₂)/2) of the maximum value h₁ and the minimum value h₂ of the lift amount of the valve body (61). Therefore, a cross sectional area of the actual outlet side flow path (70) shown in FIG. 7A is substantially equal to the cross sectional area of a virtual outlet side flow path (75) shown in FIG. 7B.

In the virtual outlet side flow path (75) shown in FIG. 7B, the front surface (61a) of the valve body (61) is parallel to the outlet end (52) of the discharge port (50), and in the case where the distance from the outlet end (52) of the discharge port (50) to the front surface (61a) of the valve body (61) is the reference lift amount ho, the virtual outlet side flow path (75) is a flow path formed between the outlet end (52) of the discharge port (50) and the valve body (61). The cross sectional shape of the virtual outlet side flow path (75) is the same as a side surface of a tubular object having a top surface parallel to its bottom surface.

In the present embodiment, the virtual outlet side flow path (75) shown in FIG. 7B is treated as being substantially equivalent to the actual outlet side flow path (70) shown in FIG. 7A. Further, the hydraulic diameter of the actual outlet side flow path (70) shown in FIG. 7A is treated as being substantially equal to the hydraulic diameter of the virtual outlet side flow path (75) shown in FIG. 7B, and is calculated based on the following Equations 4-6.

The shape of the outlet end (52) of the discharge port (50) is an oblong shape having an arc portion with a curvature radius Ro and a straight portion with a length Ls. Thus, the length (i.e., the peripheral length Lo) of the periphery (52a) of the outlet end (52) of the discharge port (50) is expressed by Equation 4 shown below.

Lo=2πRo+2Ls   (Equation 4)

Each of an upper periphery (76) and a lower periphery (77) of the virtual outlet side flow path (75) is in the same shape as the outlet end (52) of the discharge port (50), similarly to the lower periphery (72) of the actual outlet side flow path (70). The peripheral length of the virtual outlet side flow path (75) is equal to the peripheral length Lo of the outlet end (52) of the discharge port (50). Thus, a cross sectional area Ao of the virtual outlet side flow path (75) is expressed by Equation 5. Equation 5 is the same as Equation 02 described above.

Ao=Lo×ho   (Equation 5)

The wetted perimeter length of the virtual outlet side flow path (75) is a sum of its upper peripheral length and its lower peripheral length. Thus, the wetted perimeter length of the virtual outlet side flow path (75) is 2Lo. The hydraulic diameter Do of the virtual outlet side flow path (75) is therefore expressed by Equation 6. In the present embodiment, the hydraulic diameter of the actual outlet side flow path (70) is considered as being equal to the hydraulic diameter Do calculated by Equation 6, Equation 6 is the same as Equation 03 described above.

Do=4(Ao/2Lo)=2ho   (Equation 6)

The outlet end (52) of the discharge port (50) of the present embodiment has the arc portion with a curvature radius of Ro=3.1 mm, and the straight portion with a length of Ls=5.3 mm. Thus, the peripheral length Lo of the outlet end (52) of the discharge port (50) is 30.1 mm. On the other hand, the cross sectional area Ao and the hydraulic diameter Do of the virtual outlet side flow path (75) are a function of the reference lift amount ho. FIG. 8 shows the cross sectional area Ao of the flow path and the hydraulic diameter Do thereof in each of the cases where the reference lift amount ho is 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm and 1.6 mm.

<Hydraulic Diameter Rate Do/Di>

In the compressor (10) of the present embodiment, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path (70) to the hydraulic diameter Di of the inlet end (51) of the discharge port (50) satisfies the relationship defined by the Formula 7 shown below. Equation 6 shows Do=2ho. Thus, in the compressor (10) of the present embodiment, the reference lift amount ho of the valve body (61) of the discharge valve (60) is set to a value within a range defined by Formula 8.

0.25≦Do/Di≦0.5   (Formula 7)

Di/8≦ho≦Di/4   (Formula 8)

FIG. 8 shows the hydraulic diameter Do of the outlet side flow path (70) and values of the hydraulic diameter rate Do/Di in each of the cases where the reference lift amount ho is 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm and 1.6 mm. In each of the cases where the reference lift amount ho is 0.8 mm, 1.0 mm, 1.2. mm and 1.4 mm, the hydraulic diameter rate Do/Di is 0.25 or more and 0.5 or less. On the other hand, in the case where the reference lift amount ho is 1.6 mm, the hydraulic diameter rate Do/Di is larger than 0.5. Thus, each of the cases where the reference lift amount ho is 0.8 mm, 1.0 mm, 1.2 mm and 1.4 mm is an embodiment of the present application, whereas the case in which the reference lift amount ho is 1.6 mm is not an embodiment of the present application, but a comparative example.

The values of the hydraulic diameter rate Do/Di shown in FIG. 8 were calculated using Equation 9 below. Equation 9 can be obtained by substituting Equation 1 to Equation 3 and Equation 6 for Do/Di.

$\begin{array}{cc}\begin{array}{c}\mathrm{Do}\text{/}\mathrm{Di}=2\mathrm{ho}\text{/}4\left(\mathrm{Ai}\text{/}\mathrm{Li}\right)=\mathrm{ho}·\mathrm{Li}\text{/}2\mathrm{Ai}\\ =\mathrm{ho}\left(\pi \mathrm{Ri}+\mathrm{Ls}\right)\text{/}\mathrm{Ri}\left(\pi \mathrm{Ri}+2\mathrm{Ls}\right)\end{array}& \left(\mathrm{Equation}9\right)\end{array}$

—Range of Values of Hydraulic Diameter Rate Do/Di—

The reason why it is preferable to determine the reference lift amount ho of the valve body (61) of the discharge valve (60) such that the hydraulic diameter rate Do/Di is 0.25 or more and 0.5 or less will be explained.

<Pressure Loss of Discharged Refrigerant>

As shown in FIG. 9, the gas refrigerant discharged from the compressor mechanism (30) is ejected first from the outlet end (52) of the discharge port (50) to the valve body (61) of the discharge valve (60), and then collides with the front surface (61a) of the valve body (61) and changes its flow direction to spread around the outlet end (52) of the discharge port (50).

As shown in FIG. 9A, in the case where the reference lift amount ho=1.6 mm (0.5<Do/Di), a relatively large vertical vortex is generated around the outlet end (52) of the discharge port (50). The vertical vortex interrupts a flow of the gas refrigerant that is about to flow out from the outlet side flow path (70) (that is, a gap between the outlet end (52) of the discharge port (50) and the valve body (61)). Thus, the gas refrigerant can pass through only a small part of the outlet side flow path (70) closer to the valve body (61). Thus, in spite of the fact that the cross sectional area of the outlet side flow path (70) is relatively large, the pressure loss of the gas refrigerant when the gas refrigerant is passing through the outlet side flow path (70) is not much reduced.

On the other hand, as shown in FIG. 9B, in the case where the reference lift amount ho=0.8 mm (0.25≦Do/Di≦0.5), a vertical vortex is not substantially generated around the outlet end (52) of the discharge port (50). The gas refrigerant collides with the valve body (61) immediately after it is ejected from the outlet end (52) of the discharge port (50) and changes its flow direction, and passes through almost entire part of the outlet side flow path (70). Thus, in spite of the fact that the cross sectional area of the outlet side flow path (70) is smaller than in the case where the reference lift amount ho=1.6 mm, the pressure loss of the gas refrigerant when the gas refrigerant passes through the outlet side flow path (70) is almost equal to the pressure loss in the case where the reference lift amount ho=1.6 mm.

<Pulsation of Discharged Refrigerant>

The vertical vortex shown in FIG. 9A is generated and disappears several times in one discharge process. As mentioned above, the vertical vortex interrupts a flow of the gas refrigerant that is about to flow out from the outlet side flow path (70). Thus, every time the vertical vortex is generated and disappears, a flow rate of the gas refrigerant flowing out from the outlet side flow path (70) changes.

FIG. 10B, FIG. 11B, FIG. 12B and FIG. 13B show changes in a mass flow rate (that is, a discharge flow rate) of the gas refrigerant discharged from the discharge port (50) of the compressor mechanism (30). For example, in FIG. 10B, the discharge flow rate rapidly increases when the discharge valve (60) starts to separate from the outlet end (52) of the discharge port (50) at a point where a rotation angle of the drive shaft (23) is around 230°. The discharge flow rate shows a maximum value at a point where the rotation angle of the drive shaft (23) is around 250°. After that, the discharge flow rate relatively significantly changes in spite of the fact that the lift amount of the valve body (61) is approximately uniform. These changes in the discharge flow rate in the discharge process are caused by the generation and disappearance of the vertical vortex formed around the outlet end (52) of the discharge port (50).

It is preferable that the changes in the discharge flow rate are as small as possible since such changes lead to vibrations of the compressor (10) and noise. As shown in FIG. 10B, FIG. 11B, FIG. 12B and FIG. 13B, the range of the discharge flow rate in the discharge process is smaller in each of the cases where the reference lift amount ho is 0.8 mm, 1.0 mm, 1.2 mm and 1.4 mm, than in the case where the reference lift amount ho is 1.6 mm. Further, the range of the discharge flow rate in the discharge process is reduced as the reference lift amount ho becomes smaller. Thus, in the compressor (10) of the present embodiment, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the hydraulic diameter rate Do/Di is 0.5 or less.

<Delay in Closing Discharge Valve>

When the discharge valve (60) is opened/closed, the valve body (61) is elastically deformed, causing the end portion of the valve body (61) to move. The larger the reference lift amount ho of the valve body (61) is, the longer the traveling distance of the valve body (61) is when the discharge valve (60) is opened/closed. The longer traveling distance of the valve body (61) requires longer time to open/close the discharge valve (60). Thus, if the reference lift amount ho of the valve body (61) is excessively large, a phenomenon (referred to as a “delay-in-closing phenomenon”) occurs in which the valve body (61) is separated from the outlet end (52) of the discharge port (50) even at a moment when the discharge valve (60) is supposed to be closed. For example, as shown in FIG. 10A, in the case where the reference lift amount ho is 1.6 mm, the lift amount of the valve body (61) is about 0.6 mm even at a moment when the rotation angle of the drive shaft (23) reaches 360°.

When the delay-in-closing phenomenon occurs, the compression chamber (36) in an early stage of the compression process communicates with the internal space of the casing (11) through the discharge port (50), and as a result, the high-pressure gas refrigerant in the internal space of the casing (11) flows back to the compression chamber (36) through the discharge port (50). Thus, when the delay-in-closing phenomenon occurs, the mass flow rate of the refrigerant discharged from the compressor mechanism (30) per unit time is reduced, and that leads to a reduction in efficiency of the compressor (10). To avoid the reduction in efficiency of the compressor (10) caused by the delay-in-closing phenomenon of the discharge valve (60), it is preferable that the reference lift amount ho of the valve body (61) of the discharge valve (60) is as small as possible.

However, if the reference lift amount ho of the valve body (61) of the discharge valve (60) is too small, the pressure loss of the refrigerant when the refrigerant is discharged from the compressor mechanism (30) may become too large. On the other hand, as shown in FIG. 14, in the case where the hydraulic diameter rate Do/Di is relatively large, the back-flow amount of the refrigerant into the compression chamber (36) is gradually reduced as the hydraulic diameter rate Do/Di becomes smaller. However, in the case where the hydraulic diameter rate Do/Di is less than 0.25, the back-flow amount of the refrigerant into the compression chamber (36) is not reduced much even when the hydraulic diameter rate Do/Di becomes smaller. Thus, in the compressor (10) of the present embodiment, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the hydraulic diameter rate Do/Di is 0.25 or more.

—Advantages of Embodiment—

In the compressor (10) of the present embodiment, the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the hydraulic diameter rate Do/Di is 0.25 or more and 0.5 or less. It is thus possible to reduce time necessary for opening/closing the valve body (61) by reducing the reference lift amount ho of the valve body (61), without increasing the pressure loss of the refrigerant (the discharged refrigerant) discharged from the compressor mechanism (30). If the valve body (61) is opened/closed with less time, the amount of the refrigerant flowing back to the compression chamber (36) due to a delay in closing the valve body (61) reduced. Thus, in the present embodiment, it is possible to improve the efficiency of the compressor (10) by reducing the amount of the refrigerant flowing back to the compression chamber (36), while avoiding the efficiency reduction of the compression chamber (36) due to an increase in the pressure loss of the discharged refrigerant.

If the rotational speed of the compressor mechanism (30) is increased, time necessary for performing one discharge process is shortened. Thus, the higher the rotational speed of the compressor mechanism (30) is, the more it is necessary to reduce time necessary for opening/closing the valve body (61). By determining the reference lift amount ho of the valve body (61) of the discharge valve (60) such that the hydraulic diameter rate Do/Di is 0.25 or more and 0.5 or less, it is possible to reduce adverse effects caused by a delay in closing the valve body (61), even in the case where the rotational speed of the compressor mechanism (30) is very high (for example, 120 or more revolutions per second).

Further, in the compressor (10) of the present embodiment, the height H and the width W of the chamfered portion (56) satisfy the relationship of 0<H/W<0.5. That is, in the present embodiment, the chamfered portion (56) has a relatively gentle inclination. Thus, the area (i.e., the pressure receiving area) of the portion of the front surface (61a) of the valve body (61) to which pressure is applied from the discharge port (50) can be increased, and an increase in the volume of the discharge port (50) due to the provision of the chamfered portion (56) can be reduced. As a result, in the present embodiment, the efficiency reduction of the compressor (10) due to an increase in the dead volume can be reduced, and the efficiency of the compressor (10) can be improved due to a reduction in loss by overcompression.

First Variation of Embodiment

In the compressor (10) of the present embodiment, it is more preferable to determine the reference lift amount ho of the valve body (61) of the discharge valve (60) such that the hydraulic diameter rate Do/Di is 0.25 or more and 0.4 or less.

If the valve body (61) is separated from the seat portion (55) at the point when the rotation angle of the drive shaft (23) reaches 360°, the internal space of the casing (11) communicates with the suction port (42) through the discharge port (50) and the compression chamber (36), and this may result in an excess amount of refrigerant flowing back to the compression chamber (36) from the internal space of the casing (11).

On the other hand, as shown in FIG. 11, in the case where the hydraulic diameter rate Do/Di is 0.4, the lift amount of the valve body (61) becomes zero at the point when the rotation angle of the drive shaft (23) reaches 360°. That is, the discharge port (50) is completely closed at the point when the rotation angle of the drive shaft (23) reaches 360°. Further, as shown in FIG. 12 and FIG. 13, the smaller the hydraulic diameter rate Do/Di becomes, the earlier the lift amount of the valve body (61) becomes zero.

Thus, by determining the reference lift amount ho of the valve body (61) of the discharge valve (60) such that the hydraulic diameter rate Do/Di is 0.25 or more and 0.4 or less as in the present variation, it is possible to more reliably reduce the amount of refrigerant flowing back to the compression chamber (36). This will be explained with reference to FIG. 14.

Vmin shown in FIG. 14 is a lower limit of the amount of refrigerant flowing back to the compression chamber (36). That is, the amount of refrigerant flowing back to the compression chamber (36) cannot be reduced to zero because of the structure of the compressor (10). For example, in reality, it is impossible to reduce the volume of the discharge port (50) to zero, and the amount exceeding the lower limit Vmin is an amount of refrigerant flowing back to the compression chamber (36) which can be reduced. As shown in FIG. 14, the amount of refrigerant flowing back to the compression chamber (36) which can be reduced is ΔV₁ in the case where the hydraulic diameter rate Do/Di is 0.53, and ΔV₂ in the case where the hydraulic diameter rate Do/Di is 0.4.

ΔV₂ is less than half ΔV₁(ΔV₂<ΔV₁/2). Thus, by determining the reference lift amount ho of the valve body (61) of the discharge valve (60) such that the hydraulic diameter rate Do/Di is 0.4 or less, the amount of refrigerant flowing back to the compression chamber (36) can be significantly reduced. Thus, in the present variation, the efficiency of the compressor (10) can be reliably improved.

Second Variation of Embodiment

As shown in FIG. 8, in the case where the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the hydraulic diameter rate Do/Di is 0.4, the cross sectional area Ao of the virtual outlet side flow path (75) is substantially equal to the area Al of the inlet end (51) of the discharge port (50). In the case where the reference lift amount ho of the valve body (61) of the discharge valve (60) is determined such that the hydraulic diameter rate Do/Di is less than 0.4, the cross sectional area Ao of the virtual outlet side flow path (75) is smaller than the area Ai of the inlet end (51) of the discharge port (50). Thus, in the compressor (10) of the present embodiment, it is preferable to determine the reference lift amount ho of the valve body (61) of the discharge valve (60) such that the cross sectional area Ao of the virtual outlet side flow path (75) is less than or equal to the area Ai of the inlet end (51) of the discharge port (50) (Ao≦Ai).

Third Variation of Embodiment

As shown in FIG. 15, in the compressor (10) of the present embodiment, the cross sectional area of the main pass (53) of the discharge port (50) may be gradually increased from the inlet end (51) to the outlet end (52) of the discharge port (50). In the present variation, the wall surface forming the main pass (53) of the discharge port (50) is a conical surface about the center line CL of the discharge port (50). Further, in FIG. 15, the longer diameter length D₁₂ of the upper end of the main pass (53) is longer than the longer diameter length D₁₁ of the lower end of the main pass (53), and the shorter diameter length D₂₂ of the upper end of the main pass (53) is longer than the longer diameter length D₂₁ of the lower end of the main pass (53).

Fourth Variation of Embodiment

As shown in FIG. 16, in the compressor (10) of the present embodiment, the chamfered portion (56) may be omitted. The shape of the cross section of the flow path of the discharge port (50) according to the present variation is a uniform oblong shape from the inlet end (51) to the outlet end (52) of the discharge port (50).

Fifth Variation of Embodiment

As shown in FIG. 17, in the compressor (10) of the present embodiment, the cross sectional shape of the discharge port (50) may be an ellipse. In the present variation, too, the front head (31) is provided with a chamfered portion (56) around the entire periphery (52a) of the outlet end (52) of the discharge port (50). Similarly to the chamfered portion (56) shown in FIG. 5 and FIG. 6, the height H and the width W of the chamfered portion (56) of the present variation are respectively uniform around the entire periphery (52a) of the outlet end (52) of the discharge port (50). The cross sectional shape of the discharge port (50) of the present variation is not limited to an accurate ellipse having two focus points, but may be a shape whose periphery is formed by a curve and which looks like an ellipse at a glance.

Sixth Variation of Embodiment

As shown in FIG. 18, the compressor mechanism (30) of the compressor (10) of the present embodiment may be a rotary fluid machine of rolling piston type, in which the blade (43) is formed independently from the piston (38). In the compressor mechanism (30) of the present variation, the flat plate-like blade (43) is fitted in a blade groove extending in the radius direction of the cylinder (32) so as to be capable of moving to and fro, and the bushes (41) are omitted. The blade (43) is pressed against the outer circumferential surface (39) of the piston (38) by a spring (44), and the end portion of the blade (43) slides with the outer circumferential surface (39) of the piston (38).

In the compressor mechanism (30) shown in FIG. 18, the cross sectional shape of the discharge port (50) is a circle. However, the cross sectional shape of the discharge port (50) of the present variation may be an oblong shown in FIG. 6 or an ellipse shown in FIG. 17.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for a compressor having a discharge valve.

DESCRIPTION OF REFERENCE CHARACTERS

10 compressor

30 compressor mechanism

36 compression chamber

38 piston (movable side member)

45 fixed site member

50 discharge port

51 inlet end

52 outlet end

56 chamfered portion

60 discharge valve

61 valve body

Claims

1. A compressor comprising: a fixed side member forming a compression chamber; anda movable side member which is rotated and changes a volume of the compression chamber,the compressor being configured to suck a fluid into the compression chamber and to compress the fluid,the fixed side member being provided with a discharge port that penetrates the fixed side member and leads the fluid out of the compression chamber, anda discharge valve that opens/closes the discharge port,the discharge valve having a valve body which closes the discharge port by covering an outlet end of the discharge port and opens the discharge port by being titled from the outlet end of the discharge port,an area of an inlet end of the discharge port being Ai, a peripheral length of the inlet end being Li, and a hydraulic diameter Di of the inlet end being defined by Di=4(Ai/Li),a peripheral length of the outlet end of the discharge port being Lo, a reference lift amount of the valve body being ho, a cross sectional area Ao of an outlet side flow path formed between the outlet end of the discharge port and the valve body being defined by Ao=Lo×ho, and a hydraulic diameter Do of the outlet side flow path being defined by Do=4(Ao/2Lo), anda ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path to the hydraulic diameter Di of the inlet end of the discharge port being 0.25 or more and 0.5 or less.

2. The compressor of claim 1, wherein the ratio (Do/Di) of the hydraulic diameter Do of the outlet side flow path to the hydraulic diameter Di of the inlet end of the discharge port is 0.4 or less.

3. (canceled)

4. The compressor of claim 1, wherein the fixed side member is provided with a chamfered portion along an entire periphery of the outlet end of the discharge port.

5. The compressor of claim 6, wherein a height H of a chamfered portion in an axial direction of the discharge port and a width W of the chamfered portion in a direction orthogonal to the axial direction of the discharge port satisfy a relationship of 0<H/W<0.5.

6. The compressor of claim 1, wherein a cross sectional shape of the discharge port is oblong or an ellipse

7. The compressor of claim 2, wherein the fixed side member is provided with a chamfered portion along an entire periphery of the outlet end of the discharge port.

8. The compressor of claim 2, wherein a cross sectional shape of the discharge port is oblong or an ellipse.

9. The compressor of claim 3, wherein a cross sectional shape of the discharge port is oblong or an ellipse.

10. The compressor of claim 8, wherein a height H of a chamfered portion in an axial direction of the discharge port and a width W of the chamfered portion in a direction orthogonal to the axial direction of the discharge port satisfy a relationship of 0<H/W<0.5.

11. The compressor of claim 9, wherein a height H of the chamfered portion in an axial direction of the discharge port and a width W of the chamfered portion in a direction orthogonal to the axial direction of the discharge port satisfy a relationship of 0<H/W<0.5.