WO2018155209A1

WO2018155209A1 - Compressor piston, compressor, and heat pump unit

Info

Publication number: WO2018155209A1
Application number: PCT/JP2018/004384
Authority: WO
Inventors: 瑞生工藤; 元康志賀
Original assignee: 株式会社前川製作所
Priority date: 2017-02-24
Filing date: 2018-02-08
Publication date: 2018-08-30
Also published as: CN108506189B; JP6876463B2; CN208595041U; CN108506189A; JP2018138780A

Abstract

A compressor piston according to at least one embodiment of the present invention includes: a piston body having a top surface that, together with a cylinder, forms a compression chamber in which a gas is compressed; and a protrusion provided so as to protrude from the top surface along the axial direction of the piston body. The protrusion is formed such that the dimension in a direction orthogonal to the axial direction becomes smaller towards the tip end of the protrusion. The shape of a cross section of the protrusion along the direction orthogonal to the axial direction is circular. A part of the protrusion that connects to the top surface gradually reduces in diameter from the top surface to the tip end of the protrusion, and has a cross section along the axial direction that forms a concave curved surface.

Description

Piston for compressor, compressor and heat pump unit

The present disclosure relates to a piston for a compressor, a compressor, and a heat pump unit.

The compressor is applied to, for example, a refrigeration cycle and is used for compressing a refrigerant.
For example, the compressor described in Patent Document 1 is a reciprocating compressor, and includes a piston, a cylinder, a suction chamber, a discharge chamber, a suction valve, and a discharge valve. During operation of the reciprocating compressor, when power is supplied to the crankshaft from the outside and the piston reciprocates, the gas to be compressed is sucked into the cylinder from the suction chamber through the suction valve, and then compressed. Through the discharge chamber.

JP 2011-214463 A JP 2013-36381 A

In general, a reciprocating compressor includes a gas compression chamber formed by a top surface of a piston and a cylinder, a discharge chamber (exhaust chamber) for discharging compressed gas, a compression chamber and an exhaust chamber. And an exhaust valve for switching the communication state. Further, in a reciprocating compressor, a suction chamber and a suction valve may be provided in a member between a cylinder and an exhaust chamber, and a communication hole that communicates the compression chamber and the exhaust chamber passes through the above-described member. Sometimes formed. However, this communication hole becomes a dead volume (also referred to as a gap volume) for the compressor. Since the compressed gas remaining without being discharged as it is is re-expanded during the intake process, the amount of intake gas is reduced, and re-expansion / re-compression loss that requires re-compression power is generated. Will be reduced.
Therefore, like the compressor described in Patent Document 2, a dead volume is provided by providing a protrusion on the top surface of the piston so that the protrusion is inserted into the communication hole when the piston approaches the top dead center. To improve the coefficient of performance.
However, if the protrusion is not made into an appropriate shape, the compression resistance increases and the driving power of the compressor increases.
Since the adiabatic efficiency of the compressor is proportional to the volumetric efficiency and inversely proportional to the driving power, the adiabatic efficiency may decrease if the driving power of the compressor increases even if the intake gas amount increases.

In view of the above-described circumstances, at least one embodiment of the present invention aims to provide a piston for a compressor, a compressor, and a heat pump unit that can reduce dead volume and suppress a decrease in heat insulation efficiency.

(1) The compressor piston according to at least one embodiment,
A piston body having a top surface forming a compression chamber for compressing gas together with the cylinder;
A protrusion provided so as to protrude from the top surface along the axial direction of the piston main body;
With
The protrusion is
The dimension in the direction orthogonal to the axial direction is formed so as to decrease toward the tip of the protrusion,
The cross-sectional shape along the direction orthogonal to the axial direction is circular,
Of the projections, the connection portion to the top surface gradually decreases in diameter from the top surface toward the tip of the projection, and the cross section along the axial direction becomes a concave curved surface.

By using the compressor piston having the configuration (1) for the compressor, it is possible to optimize a dead volume and suppress a decrease in heat insulation efficiency. That is, as described above, in general, a reciprocating compressor includes a gas compression chamber, an exhaust chamber for discharging compressed gas, and an exhaust for switching the communication state between the compression chamber and the exhaust chamber. And a valve. Further, in the reciprocating compressor, a communication hole that communicates the compression chamber and the exhaust chamber may be formed in a member to which the exhaust valve is attached.
When the compressor piston having the configuration (1) is used in such a reciprocating compressor, when the compressor piston moves to the top dead center side in the cylinder of the compressor, a protrusion is formed in the communication hole. By intruding, the dead volume can be reduced and the re-expanded gas component can be reduced. Further, as will be described below, the compression resistance can be suppressed and the driving power of the compressor can be reduced, so that a decrease in heat insulation efficiency can be suppressed.

That is, when the compressor piston having the configuration (1) is used in the above-described reciprocating compressor, the gas compressed by the compressor piston flows through the communication hole. After the protrusion has entered the communication hole, the gas compressed by the compressor piston flows between the communication hole and the protrusion. Therefore, after the protrusion enters the communication hole, the cross-sectional area of the gas flow path in the communication hole decreases by the cross-sectional area of the protrusion.

However, according to the configuration of the above (1), the dimension in the direction orthogonal to the axial direction of the protrusion becomes smaller toward the tip of the protrusion, so that the protrusion entering the communication hole and the inner wall surface of the communication hole A gap formed between the gaps extends from the compression chamber toward the exhaust chamber. For this reason, the change of the gas flow path cross-sectional area when the protrusion starts to enter the communication hole can be mitigated, and the occurrence of overcompression due to insufficient discharge of the gas in the compression chamber can be suppressed. In addition, during the period from when the protrusion starts to enter the communication hole until the piston reaches the top dead center, the gas flowing from the compression chamber to the exhaust chamber via the gap between the protrusion and the inner wall surface of the communication hole. The flow is less likely to be disturbed. Therefore, the compression resistance can be suppressed, the driving power of the compressor can be reduced, and a decrease in heat insulation efficiency can be suppressed. Moreover, the noise and vibration of the compressor can be suppressed.
Furthermore, although the dimension in the direction orthogonal to the axial direction of the protrusion decreases toward the tip of the protrusion, the shape of the protrusion also serves as a draft when the compressor piston is manufactured by casting. If this is set, machining of the protrusion after casting can be omitted, and the manufacturing cost can be reduced.

According to the configuration of (1) above, the protrusion has a circular cross-sectional shape along the direction orthogonal to the axial direction.
In the above-described reciprocating compressor, generally, the communication hole has a circular cross-sectional shape along the axial direction of the cylinder, that is, the direction orthogonal to the axial direction of the piston main body. Therefore, according to the configuration of (1) above, since the cross-sectional shape along the direction orthogonal to the axial direction of the protrusion is the same shape as the cross-sectional shape of the communication hole, the dead volume can be efficiently reduced. Thereby, the re-expanded gas component can be reduced.

According to the configuration of (1) above, the connection portion to the top surface of the protrusions is gradually reduced in diameter from the top surface toward the tip of the protrusion, and the cross section along the axial direction becomes a concave curved surface. .

Therefore, by using the compressor piston having the configuration (1) as a compressor, the recompression power for the re-expanded gas of the compressor can be reduced, energy saving can be achieved, and noise and vibration of the compressor can be suppressed. . That is, when the compressor piston having the above-described configuration (1) is used in the above-described reciprocating compressor, among the gases flowing from the cylinder toward the communication hole and the projection, the communication hole and the projection. The gas flowing inward in the cylinder toward the inside of the cylinder can be smoothly changed from the radial direction to the axial direction by being guided along the connecting portion to the top surface of the protrusion. .
Thereby, since the flow-path resistance of the gas discharged | emitted from a cylinder can be reduced, compression resistance can be suppressed and the driving power of a compressor can be reduced, and the fall of heat insulation efficiency can be suppressed. Moreover, the noise and vibration of the compressor can be suppressed.

(2) The compressor according to at least one embodiment is:
A compressor piston configured as described in (1) above, configured to move between a top dead center and a bottom dead center to compress gas;
A cylinder forming the compression chamber together with the top surface of the compressor piston;
An exhaust valve for switching the communication state between the exhaust chamber for discharging the gas compressed by the compressor piston and the compression chamber;
A valve seat forming member including a valve seat that is formed with a communication hole that allows the compression chamber and the exhaust chamber to communicate with each other and that can contact the exhaust valve when the exhaust valve is closed;
The compressor piston is configured such that at the top dead center, at least the tip of the protrusion of the compressor piston enters the communication hole of the valve seat forming member.

According to the configuration of (2) above, the re-expanded gas component can be reduced, the compression resistance can be suppressed and the driving power of the compressor can be reduced, and the reduction in heat insulation efficiency can be suppressed. Moreover, the noise and vibration of the compressor can be suppressed.

(3) In some embodiments, in the configuration of (2) above,
When the compressor piston is located at the top dead center, the gap between the opening edge of the communication hole on the compression chamber side surface of the valve seat forming member and the side surface of the protrusion is the minimum gap,
The size of the gap between the side surface of the protrusion and the inner wall surface of the communication hole increases monotonously from the minimum gap as it approaches the tip of the protrusion.

According to the configuration of (3) above, the gap between the opening edge of the communication hole on the compression chamber side surface of the valve seat forming member and the side surface of the projection when the compressor piston is located at the top dead center is provided. When the compressor piston starts moving from the top dead center to the bottom dead center, the region in the communication hole on the exhaust chamber side of the gap and the compression chamber A pressure difference occurs. That is, when the compressor piston starts moving from the top dead center toward the bottom dead center, the pressure in the compression chamber becomes lower than the area in the communication hole on the exhaust chamber side with respect to the gap. The valve opening time can be advanced.

(4) In some embodiments, in the configuration of (3) above, a first time point when the tip of the protrusion reaches the opening edge of the communication hole on the compression chamber side surface of the valve seat forming member. Until the second time point when the compressor piston reaches the top dead center, the side surface and the inner wall surface of the communication hole are between the opening edge of the communication hole and the side surface of the protrusion. An annular hole end portion in which the gap between them is the smallest is formed.

According to the configuration of (4) above, during the period from the first time point to the second time point, the gap between the side surface and the inner wall surface of the communication hole is the opening edge of the communication hole and the protrusion. The space between the side surfaces of the exhaust chamber is the narrowest and becomes wider toward the exhaust chamber side. Therefore, during the period from the first time point to the second time point, the gas in the gap between the side surface and the inner wall surface of the communication hole is likely to flow toward the exhaust chamber side. Thereby, since the compressed gas can be efficiently exhausted, the re-expanded gas component can be reduced, the compression resistance can be suppressed, the driving power of the compressor can be reduced, and the decrease in the heat insulation efficiency can be suppressed.

(5) In some embodiments, in any one of the above configurations (2) to (4), at a position facing the top surface from the tip by 75% of the axial dimension of the protrusion. The outer diameter of the protrusion is in the range of 60% to 80% of the inner diameter of the communication hole on the compression chamber side surface of the valve seat forming member.

The dead volume can be reduced as the outer diameter of the protrusion increases. However, the larger the outer diameter of the protrusion, the smaller the gap between the protrusion and the inner wall surface of the communication hole, affecting the gas flow from the compression chamber to the exhaust chamber. Therefore, there is a possibility that the compression resistance increases and the driving power of the compressor increases.
However, according to the configuration of the above (5), the dead volume is effectively suppressed while suppressing the influence on the gas flow from the compression chamber to the exhaust chamber via the gap between the protrusion and the inner wall surface of the communication hole. Therefore, a decrease in heat insulation efficiency can be suppressed.

(6) The heat pump unit according to at least one embodiment is:
A compressor having any one of the above configurations (2) to (5);
A heat exchange unit having a heat exchanger for exchanging heat with the gas compressed by the compressor;
Heat pump cycle components,
Is provided.

According to the configuration of (6) above, it is possible to suppress a decrease in heat insulation efficiency. Thereby, energy saving of a heat pump unit can be achieved.

According to at least one embodiment of the present invention, a decrease in heat insulation efficiency can be suppressed.

It is a perspective view showing typically an internal structure of a heat pump unit provided with a compressor concerning one embodiment. It is a figure showing the whole heat pump unit composition concerning one embodiment. It is sectional drawing which shows the structure of the compressor of one Embodiment typically. It is the figure which looked at the valve plate from the compression chamber side. It is a perspective view of the piston of one embodiment. It is sectional drawing which shows the vicinity of a compression chamber and an exhaust chamber, and shows the state which the piston moved toward the top dead center and the front-end | tip of the protrusion started to penetrate into a communicating hole. It is sectional drawing which shows the vicinity of a compression chamber and an exhaust chamber, and shows the state which the piston reached | attained a top dead center. It is a figure explaining the experimental result which the inventors performed, (a) is a graph showing the experimental result which the inventors performed, (b) is 75% (0. It is a figure which shows typically the state which the protrusion penetrate | invaded into the communicating hole only for 75h).

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions that represent shapes such as quadrangular shapes, cylindrical shapes, and columnar shapes not only represent geometrically strict shapes such as quadrangular shapes, cylindrical shapes, and columnar shapes, but are within the same range In addition, the shape including the uneven portion, the chamfered portion, and the like is also expressed, and in the range where the same effect can be obtained, for example, a shape such as a cylindrical shape or a columnar shape having a conical shape is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of other constituent elements.

In the following description, the structure of the heat pump unit according to the embodiment will be described first with reference to FIG. 1, and then the heat pump cycle constituent device in the heat pump unit according to the embodiment will be described with reference to FIG. 2. To do. Then, with reference to FIG. 3, the structure of the compressor which the heat pump unit which concerns on one Embodiment has is demonstrated.
FIG. 1 is a perspective view schematically showing an internal structure of a heat pump unit including a compressor according to an embodiment. The heat pump unit 50 according to the embodiment includes a box-shaped casing 100 having a substantially rectangular parallelepiped shape, a heat exchange unit 30, and a heat pump cycle component device 52.

The box-shaped casing 100 is provided on an upper portion of a substantially rectangular base plate 51. In one embodiment, the air intake port 111 is formed in the upper region of the front surface 100 a and the back surface 100 b of the box type casing 100, and the air outlet port 112 is formed on the upper surface of the box type casing 100.
The heat exchange unit 30 according to an embodiment includes a fan 34 and a panel heat exchanger 36 provided in the box-type casing 100. Specifically, in one embodiment, a pair of panel heat exchangers 36 provided in the box casing 100 along the vertical direction are arranged facing each other. A fan 34 that allows air to pass through the pair of panel heat exchangers 36 is disposed above the pair of panel heat exchangers 36. The pair of panel-like heat exchangers 36 are provided so as to face the two air intake ports 111, and are arranged in a V shape so that the distance between the pair of panel-like heat exchangers 36 decreases toward the bottom.
As the fan 34 operates, the air flows into the box-shaped casing 100 from the air intake ports 111 provided on the front surface 100a and the back surface 100b, passes through the pair of panel heat exchangers 36, and enters the air outlet 112. A leading air flow a is formed.

FIG. 2 is a diagram illustrating an overall configuration of the heat pump unit 50 according to an embodiment. As shown in FIG. 2, the heat pump cycle component device 52 includes a compressor 200, a gas cooler 58, an internal heat exchanger 64, and a panel heat exchanger 36.
The refrigerant (for example, CO ₂ ) compressed by the compressor 200 is supplied to the gas cooler 58 through the refrigerant circulation path 54 and is cooled by the cooling water flowing through the cooling water path 60 by the gas cooler 58. The cooling water channel 60 is provided with a pump 62 that sends the cooling water to the gas cooler 58. The refrigerant cooled by the gas cooler 58 is cooled by exchanging heat with the refrigerant sent from the panel heat exchanger 36 by the internal heat exchanger 64 and then depressurized via the expansion valve 66. Thereafter, the refrigerant is heated by the panel heat. The exchanger 36 vaporizes air as a heat source. That is, the panel heat exchanger 36 is incorporated in the heat pump cycle constituent device 52 as an evaporator.
The vaporized refrigerant is heated by exchanging heat with the refrigerant sent from the gas cooler 58 by the internal heat exchanger 64 and then sent again to the compressor 200 to be compressed.

A bypass path 68 that branches from the refrigerant circulation path 54 on the downstream side of the gas cooler 58 and is connected to the refrigerant circulation path 54 on the downstream side of the expansion valve 66 is connected to the refrigerant circulation path 54. A refrigerant tank 70 is provided in the bypass path 68, and

electromagnetic valves

72 and 74 are provided on the upstream side and the downstream side of the refrigerant tank 70. A part of the refrigerant in the refrigerant circulation path 54 is stored in the refrigerant tank 70, or the refrigerant stored in the refrigerant tank 70 is returned to the refrigerant circulation path 54, whereby the amount of refrigerant flowing through the refrigerant circulation path 54 can be adjusted.
In the heat pump unit 50 of one embodiment, the hot water heated by the gas cooler 58 can be supplied to a customer as a heat source.

As shown in FIG. 1, the heat pump unit 50 according to an embodiment includes a heat exchange unit 30 in an upper region inside the box-shaped casing 100, and a compressor 200, in a lower region inside the box-shaped casing 100. A heat pump cycle component 52 such as a gas cooler 58 is provided. The heat pump cycle components 52 such as the compressor 200, the gas cooler 58, and the refrigerant tank 70 are fixed on the base plate 51.

FIG. 3 is a cross-sectional view schematically showing the structure of the compressor 200 according to one embodiment.
The compressor 200 of one embodiment is a reciprocating compressor, and includes a casing 210, a cylinder 220, a piston 230, a crankshaft 241, a connecting rod 242, a valve plate 250, and a head cover 260. In the compressor 200 shown in FIG. 3, one set of the cylinder 220 and the piston 230 is depicted, but the compressor 200 may be a single-cylinder reciprocating compressor, or a multi-cylinder reciprocating compressor. It may be. For convenience of explanation, in the following description with reference to FIG. 3, it is assumed that the extending direction of the cylinder 220 is along the vertical direction of the paper surface, and the vertical relationship of each part will be described with reference to the vertical direction of the paper surface. .

(Casing 210)
In one embodiment, a crank chamber 211 and an intake chamber 212 are provided inside the casing 210. A crankshaft 241 is rotatably supported in the crank chamber 211. A refrigerant circulation path 54 is connected to the intake chamber 212, and the refrigerant flows from the refrigerant circulation path 54.
Above the crank chamber 211, the cylinder 220 is disposed so as to extend in the vertical direction. A piston 230 is slidably inserted into the cylinder 220. Piston 230 is connected to crankshaft 241 by connecting rod 242. In FIG. 3, the description of the piston ring and the like attached to the piston 230 is omitted. A compression chamber 221 for compressing the refrigerant is formed by the top surface 232 of the piston 230 and the inner peripheral surface of the cylinder 220.

In one embodiment, the valve plate 250 is attached to the upper surface of the casing 210, and the head cover 260 is attached to the upper part of the valve plate 250. In the compressor 200 of one embodiment, an exhaust chamber 261 surrounded by the upper surface of the valve plate 250 and the inner wall surface of the head cover 260 is formed. A refrigerant circulation path 54 is connected to the exhaust chamber 261, and the refrigerant compressed in the compression chamber 221 flows out to the refrigerant circulation path 54.

(Valve plate 250)
In the valve plate 250 of one embodiment, an intake passage 251, a communication hole 252, and an exhaust valve seat 253 are formed. The intake passage 251 is a refrigerant flow path provided inside the valve plate 250 and connects the intake chamber 212 and the compression chamber 221. That is, the intake passage 251 has an upstream opening connected to the intake chamber 212 and a downstream opening 251 a connected to the compression chamber 221 via the intake valve 254.

The communication hole 252 is a refrigerant flow path that extends in the same direction as the cylinder 220 and connects the compression chamber 221 and the exhaust chamber 261, and has a circular cross section. In one embodiment, the inner diameter of the communication hole 252 is constant regardless of the axial position. In one embodiment, the central axis of the communication hole 252 coincides with the central axis of the cylinder 220, that is, the central axis of the piston 230. An opening edge 252 a of the communication hole 252 on the surface of the valve plate 250 on the compression chamber 221 side faces the compression chamber 221.
An exhaust valve 255 for switching the communication state between the exhaust chamber 261 and the compression chamber 221 is provided at the end of the communication hole 252 on the exhaust chamber 261 side. The exhaust valve 255 is attached to the valve plate 250 so as to be movable along the central axis of the communication hole 252 and is urged toward the compression chamber 221 by a spring (not shown), Is in contact with the exhaust valve seat 253.

The exhaust valve seat 253 is a valve seat with which the exhaust valve 255 abuts as described above, and on the surface of the valve plate 250 on the exhaust chamber 261 side, around the communication hole 252 having a circular shape when viewed from the exhaust chamber 261 side. Is formed. That is, the valve plate 250 of one embodiment is a valve seat forming member.

The exhaust valve 255 abuts the exhaust valve seat 253 of the valve plate 250 by the biasing force of a spring (not shown) to close the opening at the end of the communication hole 252 on the exhaust chamber 261 side, and the pressure in the compression chamber 221 increases. Then, it moves to the exhaust chamber 261 side against the urging force of a spring (not shown) and is separated from the exhaust valve seat 253 to open the opening at the end of the communication hole 252 on the exhaust chamber 261 side.

FIG. 4 is a view of the valve plate 250 as seen from the compression chamber 221 side. In FIG. 4, a circle indicated by a two-dot chain line represents the position of the inner peripheral surface 220 a of the cylinder 220. Further, in FIG. 4, the description of the intake valve 254 is omitted.
As shown in FIG. 4, in the valve plate 250 of one embodiment, a communication hole 252 is arranged so as to be coaxial with the cylinder 220. In the valve plate 250 of one embodiment, the opening 251 a on the downstream side of the intake passage 251 is provided around the opening edge 252 a of the communication hole 252. In one embodiment, the opening 251a has a long hole shape extending along a circumferential direction coaxial with the opening edge 252a having a circular shape. In one embodiment, the three openings 251a are provided at substantially equal intervals along the circumferential direction around the opening edge 252a, but the number of openings 251a is not limited to three.

(Piston 230)
FIG. 5 is a perspective view of the piston 230 of one embodiment. The piston 230 of one embodiment includes a piston main body 231 formed in a covered cylindrical shape, and a protrusion 233 provided so as to protrude from the top surface 232 of the piston main body 231 along the axis AX direction of the piston main body 231. And have. The piston main body 231 is provided with a piston pin hole 231a, and a piston ring groove 231b is provided on the outer periphery on the top surface 232 side of the piston pin hole 231a. A piston pin (not shown) for connecting to the connecting rod 242 is inserted into the piston pin hole 231a. A piston ring (not shown) is mounted in the piston ring groove 231b.

In one embodiment, the protrusion 233 is a part formed so as to be inserted into the communication hole 252 of the valve plate 250 when the piston 230 is moved from the bottom dead center to the top dead center in the cylinder 220. . That is, the piston 230 is configured such that at least the tip of the protrusion 233 enters the communication hole 252 of the valve plate 250 at the top dead center.
In one embodiment, the protrusion 233 has a substantially cylindrical shape extending along the axis AX direction. That is, in one embodiment, the protrusion 233 has a circular cross-sectional shape along a direction orthogonal to the axis AX direction. In one embodiment, the protrusion 233 is formed such that the dimension in the direction orthogonal to the axis AX direction, that is, the outer diameter becomes smaller toward the tip 233a of the protrusion 233.

In one embodiment, the protrusion 233 is formed such that the side surface 233b is linear in a cross section along the axis AX direction. Note that the connecting portion 233c of the protrusion 233 to the top surface 232 gradually decreases in diameter from the top surface 232 toward the tip 233a of the protrusion 233, and the cross section along the axis AX direction becomes a concave curved surface. In other words, the connection portion 233 c is formed so as to expand from the tip 233 a of the protrusion 233 toward the top surface 232.
In one embodiment, the length of the protrusion 233 along the axis AX direction is substantially equal to the extension length of the communication hole 252 of the valve plate 250. Thereby, dead volume can be reduced efficiently. However, for example, if the piston 230 incorporated in the compressor 200 of the embodiment does not contact the exhaust valve 255 at the top dead center, the length of the protrusion 233 along the axis AX direction. May be set as appropriate.

In the compressor 200 according to the embodiment, the refrigerant is sucked, compressed, and discharged as follows.
In the compressor 200 according to the embodiment, when the piston 230 moves in the cylinder 220 toward the bottom dead center, the pressure in the compression chamber 221 decreases, so that the refrigerant in the intake chamber 212 flows into the intake passage 251 and the valve plate 250. It flows into the compression chamber 221 through the intake valve 254. When the piston 230 moves toward the top dead center, the refrigerant in the compression chamber 221 is compressed and the pressure in the compression chamber 221 increases. As a result, the exhaust valve 255 moves to the exhaust chamber 261 side against the biasing force of a spring (not shown), the opening at the end of the communication hole 252 on the exhaust chamber 261 side is opened, and the compressed refrigerant is compressed into the compression chamber. 221 passes through the communication hole 252 and is discharged into the exhaust chamber 261.

When the piston 230 moves toward the top dead center, the refrigerant compressed in the compression chamber 221 passes through the entire inner peripheral surface of the communication hole 252 until the tip 233a of the protrusion 233 starts to enter the communication hole 252. Flowing.

FIG. 6 is a cross-sectional view showing the vicinity of the compression chamber 221 and the exhaust chamber 261, and shows a state in which the piston 230 moves toward the top dead center and the tip 233 a of the protrusion 233 starts to enter the communication hole 252. Show.
When the tip 233a of the protrusion 233 starts to enter the communication hole 252, the refrigerant compressed in the compression chamber 221 passes through the gap between the inner peripheral surface of the communication hole 252 and the side surface 233b of the protrusion 233 and is exhausted. Flow into chamber 261. Specifically, the refrigerant in the compression chamber 221 flows into the communication hole 252 from the gap between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233, as indicated by an arrow b in FIG. The gap flows between the inner peripheral surface of the communication hole 252 and the side surface 233b of the protrusion 233 toward the exhaust chamber 261 side. On the exhaust chamber 261 side from the tip 233a of the protrusion 233, as shown by the arrow c, the refrigerant flows in the entire inner peripheral surface of the communication hole 252 toward the exhaust chamber 261.

As described above, the outer diameter of the protrusion 233 becomes smaller toward the tip 233a side. Further, the inner diameter of the communication hole 252 is constant regardless of the position in the axial direction. Therefore, the size of the gap between the inner peripheral surface of the communication hole 252 and the side surface 233b of the projection 233 is the smallest in the gap between the opening edge 252a of the communication hole 252 and the side surface 233b of the projection 233. It becomes larger toward the tip 233a of the part 233. That is, the period from the first time point when the tip 233a of the protrusion 233 reaches the opening edge 252a of the communication hole 252 on the compression chamber 221 side surface of the valve plate 250 to the second time point when the piston 230 reaches top dead center. An annular hole end portion 256 is formed between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233 so that the gap between the side surface 233b and the inner wall surface of the communication hole 252 is minimized.
Therefore, the flow resistance in the gap between the inner peripheral surface of the communication hole 252 and the side surface 233b of the projection 233 is the largest at the annular hole end portion 256 and becomes smaller toward the tip 233a of the projection 233. On the downstream side of the hole end portion 256, the flow path resistance decreases, and the refrigerant easily flows toward the exhaust chamber 261 side. That is, the flow of gas from the compression chamber 221 toward the exhaust chamber 261 is not easily inhibited, so that the compression resistance can be suppressed. Therefore, the driving power of the compressor 200 can be reduced, energy saving can be achieved, and noise and vibration of the compressor 200 can be suppressed.

As described above, since the outer diameter of the protrusion 233 increases from the tip 233a toward the top surface 232 of the piston main body 231, the opening edge 252a of the communication hole 252 increases as the protrusion 233 enters the communication hole 252. And the cross-sectional area of the annular hole end portion 256 are reduced to a minimum value at the top dead center. A gap between the opening edge 252a of the communication hole 252 and the side surface 233b (connection portion 233c) of the protrusion 233 at the top dead center is referred to as a minimum gap. FIG. 7 is a cross-sectional view showing the vicinity of the compression chamber 221 and the exhaust chamber 261, and shows a state where the piston 230 has reached the top dead center.

As described above, the connecting portion 233c, which is the base of the protrusion 233, is formed so as to expand from the tip 233a side of the protrusion 233 toward the top surface 232 of the piston main body 231. Accordingly, the refrigerant flowing from the radially outer side toward the inner side in the compression chamber 221 is guided toward the exhaust chamber 261 side by flowing along the connecting portion 233c as indicated by an arrow d in FIG. . Thereby, the flow of the refrigerant becomes smooth, and the refrigerant in the compression chamber 221 can be efficiently discharged to the exhaust chamber 261.

When the protrusion 230 is not provided on the piston 230, the communication hole 252 has a so-called dead volume, but it is desired to reduce the dead volume in terms of reducing the re-expanded gas component of the compressor 200.
In one embodiment, the protrusion 233 provided so as to protrude from the top surface 232 of the piston 230 enters the communication hole 252 of the valve plate 250 in the compression and exhaust strokes of the refrigerant to reduce the dead volume. Expansion / recompression loss is improved.

In the intake stroke, when the piston 230 starts moving toward the bottom dead center after reaching the top dead center, the pressure in the compression chamber 221 starts to decrease. As described above, when the protrusion 233 enters the communication hole 252, the size of the gap between the inner peripheral surface of the communication hole 252 and the side surface 233 b of the protrusion 233 is the largest at the annular hole end portion 256. small. The cross-sectional area of the annular hole end portion 256 is the smallest at the top dead center.
Therefore, when the piston 230 starts to move toward the bottom dead center and the pressure in the compression chamber 221 begins to decrease, the inner peripheral surface of the communication hole 252 and the side surface 233b of the protrusion 233 are separated from the annular hole end portion 256. A pressure difference is generated between the gap between the compression chamber 221 and the compression chamber 221. That is, the pressure in the compression chamber 221 is lower than the pressure in the gap between the inner peripheral surface of the communication hole 252 and the side surface 233b of the protrusion 233. As a result, the opening timing of the intake valve 254 can be advanced, so that the refrigerant efficiently flows into the compression chamber 221, so that the inflow resistance of the compressor 200 can be reduced.

As described above, in one embodiment, the piston 230 includes the piston body 231 having the top surface 232 that forms the compression chamber 221 that compresses the gas together with the cylinder 220, and the top surface along the axial direction of the piston body 231. And a protrusion 233 provided so as to protrude from the H.232.
When the piston 230 is used in the compressor 200 described above, when the piston 230 moves to the top dead center side in the cylinder 220 of the compressor 200, the protrusion 233 enters the communication hole 252, thereby reducing the dead volume. Can be reduced. Therefore, the re-expanded gas component of the compressor 200 can be reduced.

The protrusion 233 is formed so that the dimension in the direction orthogonal to the axial direction of the piston main body 231 decreases as it goes toward the tip 233 a of the protrusion 233.
When the piston 230 is used in the compressor 200 described above, the refrigerant compressed by the piston 230 flows through the communication hole 252. After the protrusion 233 enters the communication hole 252, the refrigerant compressed by the piston 230 flows between the communication hole 252 and the protrusion 233. Therefore, after the protrusion 233 enters the communication hole 252, the cross-sectional area of the refrigerant flow path in the communication hole 252 decreases by the cross-sectional area of the protrusion 233.

However, since the dimension of the protrusion 233 in the direction orthogonal to the axial direction becomes smaller toward the tip 233a of the protrusion 233, it is formed between the protrusion 233 that has entered the communication hole 252 and the inner wall surface of the communication hole 252. The gap is expanded from the compression chamber 221 toward the exhaust chamber 261. For this reason, the change of the flow path cross-sectional area of the gas when the protrusion 233 starts to enter the communication hole 252 can be alleviated, and the exhaust of the gas in the compression chamber 221 is insufficient and the occurrence of overcompression is suppressed. it can. Further, in a period from when the protrusion 233 starts to enter the communication hole 252 until the piston 230 reaches the top dead center, the compression chamber 221 is separated from the compression chamber 221 through a gap between the protrusion 233 and the inner wall surface of the communication hole 252. The gas flow toward the exhaust chamber 261 is not easily inhibited. Therefore, since compression resistance can be suppressed and the driving power of the compressor 200 can be reduced, energy saving can be achieved, and noise and vibration of the compressor 200 can be suppressed.
Further, although the dimension of the projection 233 in the direction orthogonal to the axial direction decreases toward the tip 233a of the projection 233, the projection 233 also serves as a draft that is set when the piston 230 is manufactured by casting. If the shape is set, machining of the projection 233 after casting can be omitted, and the manufacturing cost can be reduced.

The protrusion 233 has a circular cross-sectional shape along a direction orthogonal to the axial direction.
The communication hole 252 has a circular cross-sectional shape along a direction perpendicular to the axial direction of the cylinder 220, that is, the axial direction of the piston main body 231. Therefore, since the cross-sectional shape along the direction orthogonal to the axial direction of the protrusion 233 becomes the same shape as the cross-sectional shape of the communication hole 252, the dead volume can be efficiently reduced. Thereby, the reexpansion / recompression loss of the compressor 200 can be improved.

The connecting portion 233c of the protrusion 233 to the top surface 232 is gradually reduced in diameter from the top surface 232 toward the tip 233a of the protrusion 233, and the cross section along the axial direction becomes a concave curved surface.
When the piston 230 is used in the compressor 200, the refrigerant compressed by the piston 230 flows between the communication hole 252 and the protrusion 233 after the protrusion 233 enters the communication hole 252. Of the refrigerant that flows from the inside of the cylinder 220 toward the communication hole 252 and the protrusion 233, the refrigerant that flows radially inside the cylinder 220 toward the space between the communication hole 252 and the protrusion 233 is the protrusion 233. The direction of the flow can be smoothly changed from the radial direction to the axial direction by being guided along the connection portion 233c to the top surface 232.
Thereby, since the flow path resistance of the refrigerant | coolant discharged | emitted from the cylinder 220 can be reduced, compression resistance can be suppressed. Therefore, the driving power of the compressor 200 can be reduced, energy saving can be achieved, and noise and vibration of the compressor 200 can be suppressed.

The protrusion 233 is formed such that the dimension in the axial direction of the piston main body 231 is larger than the dimension in the direction orthogonal to the axial direction.
In the compressor 200 of one embodiment, since the intake passage 251 is provided in the valve plate 250, the valve plate is thicker than a valve plate in which no refrigerant intake passage is provided. The extending length of the communication hole 252 tends to be long. Further, in the compressor 200 according to the embodiment, as shown in FIG. 4, since the downstream side opening 251 a of the intake passage 251 is provided around the communication hole 252, the downstream of the intake passage is provided around the communication hole 252. The diameter of the communication hole 252 tends to be smaller than that of a valve plate that is not provided with a side opening. Therefore, in one embodiment, the extension length of the communication hole 252 is larger than the diameter of the communication hole 252.

When the piston 230 is used in the compressor 200 of the embodiment, the refrigerant compressed by the piston 230 flows through the communication hole 252. After the protrusion 233 enters the communication hole 252, the refrigerant compressed by the piston 230 flows between the communication hole 252 and the protrusion 233. Therefore, after the protrusion 233 enters the communication hole 252, the cross-sectional area of the refrigerant flow path in the communication hole 252 decreases by the cross-sectional area of the protrusion 233.
However, since the projecting portion 233 is formed so that the dimension of the piston main body 231 in the axial direction is larger than the dimension in the direction orthogonal to the axial direction, the passage of the refrigerant in the communication hole 252 is secured while Since the volume can be efficiently reduced, the compression resistance can be suppressed, the driving power of the compressor can be reduced, and a decrease in the heat insulation efficiency can be suppressed.

The compressor which concerns on one Embodiment forms the compression chamber 221 with said piston 230 comprised so that it may move between a top dead center and a bottom dead center, and compresses gas, and the top surface 232 of piston 230 A cylinder 220, an exhaust valve 255 for switching the communication state between the exhaust chamber 261 and the compression chamber 221 for discharging the refrigerant compressed by the piston 230, and a communication hole for communicating the compression chamber 221 and the exhaust chamber 261. And a valve plate 250 including an exhaust valve seat 253 with which the exhaust valve 255 can come into contact when the exhaust valve 255 is closed. At the top dead center of the piston 230, at least the tip 233 a of the protrusion 233 of the piston 230 enters the communication hole 252 of the valve plate 250.
Thereby, when the piston 230 moves to the top dead center side in the cylinder 220, the dead volume can be reduced by the protrusion 233 entering the communication hole 252, and the re-expansion / re-compression loss of the compressor 200 is improved. it can.

The valve plate 250 is provided inside the valve plate 250 and has an intake passage 251 for guiding the refrigerant to the compression chamber 221.
Thus, the inside of the valve plate 250 can be effectively used as an intake passage, and the compressor 200 can be downsized.

When the piston 230 is located at the top dead center, the gap between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233 on the surface of the valve plate 250 on the compression chamber 221 side is the minimum gap. The size of the gap between the side surface 233b of the protrusion 233 and the inner wall surface of the communication hole 252 monotonously increases from the minimum gap as it approaches the tip 233a of the protrusion 233.
Thereby, when the piston 230 is located at the top dead center, the gap between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233 on the surface of the valve plate 250 on the compression chamber 221 side becomes the minimum gap. Therefore, when the piston 230 starts to move from the top dead center toward the bottom dead center, the pressure difference between the compression chamber 221 and the region in the communication hole 252 closer to the exhaust chamber 261 than the gap is the boundary. Occurs. That is, when the piston 230 starts moving from the top dead center toward the bottom dead center, the pressure in the compression chamber 221 becomes lower than the area in the communication hole 252 on the exhaust chamber 261 side with respect to the gap. The valve opening timing of the valve 254 can be advanced, and the refrigerant efficiently flows into the compression chamber 221, so that the re-expanded gas component of the compressor 200 can be reduced.

During the period from the first time point when the tip 233a of the protrusion 233 reaches the opening edge 252a of the communication hole 252 on the compression chamber 221 side surface of the valve plate 250 to the second time point when the piston 230 reaches top dead center Between the opening edge 252a of the hole 252 and the side surface 233b of the protrusion 233, an annular hole end portion 256 where the gap between the side surface 233b and the inner wall surface of the communication hole 252 is minimized is formed.
Accordingly, during the period from the first time point to the second time point, the gap between the side surface 233b and the inner wall surface of the communication hole 252 is narrowest between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233. It becomes wider as it goes to the exhaust chamber 261 side. Therefore, during the period from the first time point to the second time point, the refrigerant in the gap between the side surface 233b and the inner wall surface of the communication hole 252 can easily flow toward the exhaust chamber 261 side. Thereby, since the compressed refrigerant can be exhausted efficiently, the re-expanded gas component of the compressor 200 can be reduced.

Thus, in the above-described embodiment, the re-expansion / recompression loss can be improved by reducing the re-expansion gas content of the compressor 200 while suppressing the decrease in the heat insulation efficiency.

As described above, as the diameter of the protrusion 233 increases, the dead volume can be reduced and the re-expanded gas can be reduced. However, the cross-sectional area of the refrigerant flow path between the communication hole 252 and the protrusion 233 is reduced. And the refrigerant flow from the compression chamber 221 toward the exhaust chamber 261 is affected. That is, if the protrusion is not made into an appropriate shape, the compression resistance increases and the driving power of the compressor increases, so that the heat insulation efficiency of the compressor 200 may be reduced.

Therefore, the inventors conducted experiments on a plurality of patterns with different diameters of the protrusions 233, and verified how the heat insulation efficiency of the compressor changes depending on the diameter of the protrusions 233.

As described above, since the side surface 233b of the protrusion 233 has a tapered shape, in the following description, 75% (0.75 h) of the dimension h in the axis AX direction of the protrusion 233 from the tip 233a of the protrusion 233. Only the diameter at the position facing the top surface 232 side is adopted as a representative value of the diameter of the protrusion 233. Hereinafter, the representative value of the diameter is simply referred to as a representative diameter d (see FIG. 8B).

FIG. 8 is a diagram for explaining the experimental results conducted by the inventors, FIG. 8A is a graph showing the experimental results conducted by the inventors, and FIG. It is a figure which shows typically the state which the protrusion 233 penetrate | invaded into the communicating hole 252 only by 75% (0.75h) of the dimension h.
In FIG. 8A, the diameter ratio Φ is a value obtained by dividing the representative diameter d by the inner diameter (communication hole diameter) D of the communication hole 252 at the opening edge 252a. FIG. 8A is a graph of the adiabatic efficiency ηad of the compressor used in the experiment. In FIG. 8A, each plot of rhombus, square, and triangle for the adiabatic efficiency ηad corresponds to each of the experimental results under three different experimental conditions with the refrigerant suction pressure and exhaust pressure changed. .

Although not shown, as the diameter ratio Φ increases, the driving power increases and the degree of increase in the driving power increases. Although not shown, the volume efficiency increases in proportion to the diameter ratio Φ as the diameter ratio Φ increases.
Therefore, as shown in FIG. 8 (a), the heat insulation efficiency ηad is maximized at a predetermined diameter ratio Φ (near Φ = 0.7), and even if the diameter ratio Φ is larger than the predetermined diameter ratio Φ, Even if it gets smaller, it drops.

From the above, the diameter ratio Φ should be set within the range of 60% or more and 80% or less in order to reduce the re-expansion gas component and suppress the decrease in heat insulation efficiency while improving the re-expansion / re-compression loss. Is desirable.

The heat pump unit 50 according to the embodiment includes the above-described compressor 200, the heat exchange unit 30 having the panel heat exchanger 36 for exchanging heat with the refrigerant compressed by the compressor 200, and the heat pump cycle constituent device 52. With.
Thereby, since the re-expansion gas content of the compressor 200 can be reduced and the re-expansion / re-compression loss can be improved and the decrease in the heat insulation efficiency can be suppressed, energy saving of the heat pump unit 50 can be achieved.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said form, A various change is possible in the range which does not deviate from the objective of this invention.

In the above-described embodiment, the protrusion 233 is formed so that the dimension of the piston main body 231 in the direction orthogonal to the axis AX direction decreases toward the tip 233a of the protrusion 233. That is, in the above-described embodiment, the side surface 233b of the protrusion 233 has a tapered shape. However, for example, the side surface 233b of the protrusion 233 may not have a tapered shape.

In the above-described embodiment, no particular mention is made as to whether the protrusion 233 is solid or hollow. However, the protrusion 233 may be solid or hollow.

In the above-described embodiment, the protrusion 233 has a circular cross-sectional shape along a direction orthogonal to the axis AX direction. However, the projecting portion 233 may have a cross-sectional shape other than a circular shape along a direction orthogonal to the axis AX direction, for example, an elliptical shape, a polygonal shape, a straight line or a curved line The shape which combined suitably may be sufficient.

In the above-described embodiment, the protrusion 233 is formed so as to expand from the tip 233a of the protrusion 233 toward the top surface 232 at the connection portion 233c. However, for example, the cross section along the axial direction of the connecting portion 233c of the protrusion 233 may not be a concave curved surface, and the side surface 233b and the top surface 232 may intersect with each other.

In the above-described embodiment, the protrusion 233 is formed so that the dimension in the axis AX direction is larger than the dimension in the direction orthogonal to the axis AX direction. However, for example, the protrusion 233 has the same dimension in the axis AX direction as the dimension in the direction orthogonal to the axis AX direction, or the dimension in the axis AX direction is smaller than the dimension in the direction orthogonal to the axis AX direction. It may be formed.

In the above-described embodiment, the valve plate 250 is provided with the intake passage 251 that is a refrigerant flow path. However, for example, the flow path for introducing the refrigerant into the compression chamber 221 may not be provided inside the valve plate 250.

In the above-described embodiment, the gap between the side surface 233b and the inner wall surface of the communication hole 252 is the smallest between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233 at the top dead center. However, for example, at the top dead center, the gap between the side surface 233b and the inner wall surface of the communication hole 252 may be the smallest on the exhaust chamber 261 side than the opening edge 252a of the communication hole 252.

In the above-described embodiment, the piston 230 reaches the top dead center from the first time point when the tip 233a of the protrusion 233 reaches the opening edge 252a of the communication hole 252 on the compression chamber 221 side surface of the valve plate 250. During the period up to two time points, the gap between the side surface 233b and the inner wall surface of the communication hole 252 is the smallest between the opening edge 252a of the communication hole 252 and the side surface 233b of the protrusion 233. However, during the period from the first time point to the second time point, the gap between the side surface 233b and the inner wall surface of the communication hole 252 may be the smallest on the exhaust chamber 261 side than the opening edge 252a of the communication hole 252.

For example, in the above-described embodiment, the heat pump unit 50 including the devices that configure the heat pump cycle has been described. However, the above-described content of the heat pump unit 50 can be applied to a refrigeration unit including the devices that configure the refrigeration cycle.

30 heat exchange unit 34 fan 36 panel heat exchanger 50 heat pump unit 51 base plate 52 heat pump cycle component equipment 54 refrigerant circulation path 58 gas cooler 60 cooling water path 62 pump 64 internal heat exchanger 66 expansion valve 68 bypass path 70 refrigerant tank 100 box type Casing 111 Air intake port 112 Air outlet port 200 Compressor 210 Casing 211 Crank chamber 212 Intake chamber 220 Cylinder 220a Inner circumferential surface 221 Compression chamber 230 Piston 231 Piston body portion 232 Top surface 233 Projection portion 233a Tip

233b Side surface

233c Connection portion 241 Crank Shaft 250 Valve plate 251 Intake passage 251a Opening 252 Communication hole 252a Opening edge 253 Exhaust valve seat 254 Intake valve 255 Exhaust valve 256 Annular hole end 60 a head cover 261 exhaust chamber a airflow AX axis

Claims

A piston body having a top surface forming a compression chamber for compressing gas together with the cylinder;
A protrusion provided so as to protrude from the top surface along the axial direction of the piston main body;
With
The protrusion is
The dimension in the direction orthogonal to the axial direction is formed so as to decrease toward the tip of the protrusion,
The cross-sectional shape along the direction orthogonal to the axial direction is circular,
The connecting portion to the top surface of the projecting portion gradually decreases in diameter from the top surface toward the tip of the projecting portion, and the cross section along the axial direction is a concave curved surface.
The compressor piston according to claim 1, wherein the compressor piston is configured to move between a top dead center and a bottom dead center to compress gas.
A cylinder forming the compression chamber together with the top surface of the compressor piston;
An exhaust valve for switching the communication state between the exhaust chamber for discharging the gas compressed by the compressor piston and the compression chamber;
A valve seat forming member including a valve seat that is formed with a communication hole that allows the compression chamber and the exhaust chamber to communicate with each other and that can contact the exhaust valve when the exhaust valve is closed;
The compressor piston is configured such that at the top dead center, at least the tip of the protrusion of the compressor piston enters the communication hole of the valve seat forming member.
When the compressor piston is located at the top dead center, the gap between the opening edge of the communication hole on the compression chamber side surface of the valve seat forming member and the side surface of the protrusion is the minimum gap,
The compressor according to claim 2, wherein the size of the gap between the side surface of the protrusion and the inner wall surface of the communication hole monotonously increases from the minimum gap as it approaches the tip of the protrusion.
A second time point when the compressor piston reaches the top dead center from a first time point when the tip of the protrusion reaches the opening edge of the communication hole on the compression chamber side surface of the valve seat forming member. An annular hole end portion in which the gap between the side surface and the inner wall surface of the communication hole is the smallest is formed between the opening edge of the communication hole and the side surface of the protrusion during the period up to The compressor described in 1.
The outer diameter of the protrusion at a position from the tip toward the top surface side by 75% of the axial dimension of the protrusion is the surface of the communication hole on the compression chamber side surface of the valve seat forming member. The compressor according to any one of claims 2 to 4, which is in a range of 60% to 80% of the inner diameter.
A compressor according to any one of claims 2 to 5;
A heat exchange unit having a heat exchanger for exchanging heat with the gas compressed by the compressor;
Heat pump cycle components,
A heat pump unit comprising: