JP2000145641A - Reciprocating compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reciprocating compressor for CO2 cycle which can improve COP of refrigeration cycle while suppressing increase of discharge temperature of coolant. SOLUTION: When a piston 15 is moved to the side of a bottom dead center inside a cylinder 25, coolant is flowed into the cylinder 25 from the outside through coolant suctioning passages 56, 57 and valve mechanisms 33, 36. When the piston 15 reaches the bottom dead center, the coolant is flowed into the cylinder 25 through intermeidate pressure suctioning passages 58, 60 on a cylinder head 13 and an intermediate pressure suctioning opening 27 formed on the cylinder 25. The coolant is mixed with the coolant which is former flowed into the cylinder 25 through the coolant suctioning passages 56, 57 and the valve mechanisms 33, 36. By feeding the coolant of low temperature into the intermediate suctioning passages 58, 60 from the outside, the temperature of the coolant flowed into the cylinder 25 through the coolant suctioning passages 56, 57 and the valve mechanisms 33, 36 is lowered. A discharge temperature of the coolant is kept low after compression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating compressor suitably used for an air conditioning system for automobiles, business use, or home use.

[0002]

2. Description of the Related Art In the world where it is required worldwide to prevent global warming due to chlorofluorocarbon gas, in the technical field of a vapor compression refrigeration system that has used chlorofluorocarbon as a refrigerant, one of the measures for removing chlorofluorocarbon is one of the measures. For example, a vapor compression refrigeration cycle using carbon dioxide (CO ₂ ) (hereinafter abbreviated as a CO ₂ cycle) has been proposed.

FIG. 8 shows a circuit of a conventional CO ₂ cycle. This vapor compression refrigeration cycle 101 (hereinafter simply referred to as refrigeration cycle 101) is a refrigerant CO _2.
102, a radiator (gas cooler) 103 for exchanging heat between the refrigerant compressed by the compressor 102 and the outside air or the like to cool the refrigerant, and a refrigerant CO ₂ disposed downstream of the gas cooler 103. Gas-liquid separator 104 that stores the gas in two phases, a gas phase and a liquid phase, an expansion valve 105 that controls the pressure of the refrigerant flowing out of the gas-liquid separator 104, and a refrigerant that evaporates and compresses the refrigerant from the expansion valve 105. Evaporator 10 to be supplied to the heater 102
6 is provided.

[0004] The operation principle of such a refrigeration cycle 101 is the same as that of a conventional refrigerant using refrigerant. That is, in the refrigeration cycle 101, the compressor 102 compresses the refrigerant CO ₂ in a gaseous state, and thereby cools the CO ₂ in a supercritical state at a high temperature and a high pressure by the gas cooler 103.
Then, the cooled CO ₂ is temporarily stored in the gas-liquid separator 104. Further, CO flowing out of the gas-liquid separator 104
₂ is decompressed by the expansion valve 105 and then evaporates in the evaporator 106 to take heat from the outside and enter a gaseous state,
The refrigerant CO _{2 in the} gaseous state is supplied to the compressor 102 again and compressed.

[0005]

However, in such a CO ₂ cycle, the coefficient of performance (COP) of the refrigeration cycle is higher than that in the case of using chlorofluorocarbon.
Performance) was poor, so improving this was a challenge.

As a method of improving the COP of the CO ₂ cycle, for example, a gas cooler 10 using an internal heat exchanger is used.
There is a method of performing heat exchange between the refrigerant from the outlet 3 and the refrigerant from the outlet of the evaporator 107. However, in this method,
There is a problem that the discharge temperature of the compressor 102 rises and oil (lubricating oil) inside the compressor deteriorates.

The present invention has been proposed in view of such circumstances, and provides a reciprocating compressor for a CO ₂ cycle that can improve the COP of a refrigeration cycle while suppressing an increase in refrigerant discharge temperature. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cylinder block having a front housing in which a drive shaft is rotatably held, and a cylinder connected to the front housing and accommodating a piston. A cylinder head formed with a refrigerant passage connected to the cylinder block and communicating with the cylinder; and a valve mechanism disposed between the cylinder block and the cylinder head, and a rotational drive transmitted from an external drive source. In a reciprocating compressor, in which force is transmitted to a piston through a drive shaft, a refrigerant from the outside is sucked in by the piston, compressed, and circulated through an air conditioning system. A refrigerant suction passage for supplying a refrigerant from the outside via a valve mechanism, and a refrigerant compressed by a piston in a cylinder. A refrigerant discharge passage for discharging to the outside through the structure, is divided into an intermediate pressure suction path for sucking the refrigerant from the outside as an intermediate pressure, the cylinder block,
An intermediate pressure suction opening communicating with the intermediate pressure suction passage and supplying the intermediate pressure from the intermediate pressure suction passage to the inside of the cylinder is formed near the bottom dead center of the cylinder.

In the reciprocating compressor of the present invention, when the piston moves toward the bottom dead center in the cylinder, the refrigerant from the outside flows into each cylinder through the refrigerant suction passage of the cylinder head and the valve mechanism. When the piston reaches the bottom dead center, the refrigerant from the outside flows into the cylinder through the intermediate pressure suction passage of the cylinder head and the intermediate pressure suction opening formed in the cylinder. Is mixed with the refrigerant flowing into the respective cylinders.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. A reciprocating compressor to which the present invention is applied is used as a compressor of a vapor compression refrigeration cycle as shown in FIG. That is, the vapor compression refrigeration cycle 1 (hereinafter, simply referred to as refrigeration cycle 1) of FIG. 1 is mounted on a vehicle such as an automobile, for example, and uses carbon dioxide (CO ₂ ) as a refrigerant and this refrigerant. 2 which compresses the refrigerant in a gaseous state, and a radiator (gas cooler) which exchanges heat between the refrigerant compressed by the compressor 2 and the outside air to cool the refrigerant.
3, a first expansion valve 4 disposed downstream of the gas cooler 3 to control the pressure of the refrigerant from the gas cooler 3, and a refrigerant CO ₂ disposed downstream of the first expansion valve 4 to convert the refrigerant CO ₂ into a gas phase and a liquid phase 2. A gas-liquid separator 5 that stores the liquid in phases, a second expansion valve 6 that controls the pressure of the refrigerant flowing out of the gas-liquid separator 5, and a refrigerant that evaporates from the second expansion valve 6 and is supplied to the compressor 2 The evaporator 7 is provided.

[0011] In the refrigeration cycle 1, as shown in FIG. 1, in the compressor 2 and the gas cooler 3 and the pipe P _1, a gas cooler 3 and the first expansion valve 4 is in the pipe P _2, the first expansion valve 4
And in the gas-liquid separator 5 and the pipe P _3, a gas-liquid separator 5 by the second expansion valve 6 and the piping P _4, the evaporator 7 and it is a pipe P ₅ and the second expansion valve 6, an evaporator 7 a compressor 2 through a pipe P _6, further a gas-liquid separator 5 and the compressor 2 is a pipe P _7, are connected with.

Next, the configuration of the compressor 2 used in the refrigeration cycle 1 will be described. As shown in FIG. 2, the compressor 2 is a reciprocating compressor that obtains a compressive force by reciprocating a plurality of pistons. In this embodiment, six compressors are provided. The compressor 2 is configured such that the rotational driving force transmitted to the drive shaft is transmitted to the six pistons through a crank mechanism including a swash plate, a swing plate, and the like.

As shown in FIG. 2, the compressor 2 includes a front housing 11, a cylinder block 12, and a cylinder head 13, which constitute a compressor casing as a housing. In this compressor casing, a space formed by the front housing 11 and the cylinder block 12 is a crank chamber 20. In the crank chamber 20, a swash plate 18 integrated with the drive shaft 14, Plate 1 that swings with the rotation of
9, a piston rod 21 attached to the swing plate 19 and the like are provided. In the compressor casing, FIG.
As shown in FIG. 4 to FIG. 4, cylinders 25 are formed at six locations so as to communicate with the crank chamber 20.
5 is provided with a piston 15.

FIG. 3 is a perspective view from the cylinder head 13 side. FIG. 2 shows a cross section taken along the line AB in FIG.

In the compressor 2, a through hole 16 for supporting the drive shaft 14 is formed at the center of the front housing 11, and the drive shaft 14 is formed in the through hole 16.
Is rotatably mounted via a bearing 17. Also,
A swash plate 18 is connected to the drive shaft 14, and both are integrated. The swash plate 18 has a substantially circular plane shape,
As shown in FIG. 2, it has an upper surface (inclined surface) inclined at a predetermined angle with respect to the bottom surface.

An oscillating plate 19 is mounted on the swash plate 18 so as to be rotatable relative to the inclined surface. Further, the oscillating plate 19 is connected to each piston 15 via a piston rod 21. Connected by universal joint (universal joint) method. The oscillating plate 19 is supported via a spherical bearing 24 by a support member 23 attached to a through hole 22 at the center of the cylinder block 12. The rocking plate 19 and the support member 23 are provided with locking portions near the mounting position of the bearing 24, respectively.
3 is prevented from rotating. Thereby, the swing plate 19
Does not rotate as the swash plate 18 rotates.

In the cylinder block 12, FIGS.
As shown in FIG.
Are provided on concentric circles around the through-hole portion 22 and have the same diameter.

At the upper end of each cylinder 25,
A valve receiving portion (recess) 26 for limiting the amount of movement of a suction valve described later is formed at a position facing the outside of the cylinder block 12. And in the cylinder block 12,
An intermediate pressure suction opening 27, which is a slit-shaped hole for communicating the cylinder 25 with a space outside the cylinder 25, is provided under each of the cylinders 25.
It is formed part by part. This intermediate pressure suction opening 27 is
Normally, it is formed at a position where communication with the external space is prevented by the side surface of the piston 15 and the cylinder 25 and the external space communicate with each other when the piston 15 reaches the bottom dead center.

As shown in FIGS. 2 and 5A, the valve plate 31 is a plate-like member having an outer shape equal to the planar shape of the upper surface of the cylinder block 12, and is provided at the center position of the main surface.
A center hole 32 for screwing each valve member and the like described later is provided. On the main surface of the valve plate 31, six suction holes 33 for supplying the refrigerant to the cylinder 25 are formed concentrically around the center hole 32. Further, on the main surface of the valve plate 31, six discharge holes 34 for discharging the refrigerant compressed by the cylinder 25 are formed on a concentric circle inside the suction hole 33 around the center hole 32. .

On one main surface of the valve plate 31, FIG.
The suction valve member 35 shown in FIG. The suction valve member 35 is made of a thin plate-shaped spring member, and is equally branched in six directions from the center of the main surface to form a suction valve 36.
Are formed. In the suction valve member 35, a center hole 37 for screwing is provided at the center position of the main surface, and six discharge holes 38 are formed concentrically around the center hole 37. . This discharge hole 38 is
It is provided on the base end side of the suction valve 36 at a position corresponding to the discharge hole 34 of the valve plate 31.

A discharge valve member 41 shown in FIG. 5C is attached to the other main surface of the valve plate 31. The discharge valve member 41 is made of a thin plate-shaped spring member, and is equally branched in six directions from the center of the main surface to form a discharge valve 4.
2 are formed. In the discharge valve member 41, a center hole 43 for screwing is provided at the main surface center position, and the distance from the main surface center position to the tip of the discharge valve 42 is
The distance from the center position of the main surface of the valve plate 31 to the discharge hole 34 is slightly longer.

Further, a discharge valve retainer 44 shown in FIG. 2 for restricting the amount of movement of each discharge valve 42 is mounted above the discharge valve member 41 (right side in FIG. 2). The retainer 44 has substantially the same planar shape as the discharge valve member 41, and the tip side is warped up as shown in FIG.

In the compressor 2, these members are aligned and screwed with bolts 47 and nuts 48, so that each of the discharge holes 34 of the valve plate 31 has a corresponding suction valve member 3.
The discharge holes 38 communicate with each other, and these holes are closed by the distal ends of the discharge valves 42. Also, the valve plate 31
Each of the suction holes 33 is closed by the distal end side of each suction valve 36 of the suction valve member 35.

As shown in FIG. 2 and FIG. 6 showing a plan view from the inside, the cylinder head 13 has a generally bowl-shaped outer shape, and the center of one main surface rises and a wall portion 51 is formed.
Surrounded by Further, a peripheral portion 52 having a plane having the same height as the rising wall portion 51 is formed outside the rising wall portion 51 in the cylinder head 13, and a side wall portion 53 is formed from the outside of the peripheral portion 52. .

In the cylinder head 13, as shown in FIG. 6, a discharge port 54 is provided substantially at the center of the main surface.
A discharge chamber 55, which is a space surrounded by the rising wall 51, communicates with the discharge port 54. In the cylinder head 13, a suction port 56 is provided on a main surface surrounded by the rising wall portion 51 and the peripheral edge portion 52, and the rising wall portion 51 is provided.
A suction chamber 57, which is a space surrounded by the peripheral portion 52 and the suction port 56, communicates with each other. Further, an intermediate pressure suction port 58 is provided in the side wall 53 of the cylinder head 13.

In the compressor 2, the valve plate 31 on which the above-described valve members and the like constituting the valve mechanism are mounted and the cylinder head 13 are aligned and assembled on the upper part of the cylinder block 12, so as to be assembled as shown in FIGS. The positional relationship is as shown in FIG. Specifically, each cylinder 25 of the cylinder block 12 is provided with a suction hole 33 in the valve plate 31.
The discharge hole 34, the suction valve 36, and the discharge valve 42 are located, and the tip end side of the suction valve 36 is located with respect to each of the recesses 26 of the cylinder 25. The discharge hole 34 and the suction hole 33 of the valve plate 31 communicate with the discharge chamber 55 and the suction chamber 57 of the cylinder head 13, respectively. Further, the upper part of the cylinder block 12 and the cylinder head 13
The space surrounded by the peripheral portion 52 and the side wall 53 of the cylinder block serves as an intermediate pressure suction chamber 60. The intermediate pressure suction chamber 60 is formed by the intermediate pressure suction opening 27 of the cylinder block 12 and the intermediate pressure suction port 58 of the cylinder head 13. Communicate with

In operation of the compressor 2 having such a configuration, the pipe P ₆ from the outlet of the evaporator 7 in FIG. 1 is connected to the suction port 56 of the cylinder head 13 and the pipe to the inlet of the gas cooler 3. P ₁ is connected to the discharge port 54 of the cylinder head 13. The pipe P ₇ to which the refrigerant CO ₂ as the intermediate pressure from the gas-liquid separator 5 is supplied is connected to the intermediate pressure suction port 58 of the cylinder head 13.

In the compressor 2, when the drive shaft 14 and the swash plate 18 are rotated by an external drive source such as an engine or a motor, the rocking plate 19 moves around the center of the bearing 24 in the crank chamber 20. The piston 15 swings, and each of the pistons 15 reciprocates via the piston rod 21 with the swing. At this time, in the compressor 2, the refrigerant CO ₂ from the evaporator 7 flowing into the suction chamber 57 from the pipe P ₆ through the suction port 56 is supplied to the cylinder 25 whose pressure is reduced by the piston 15 moving to the bottom dead center side. Inhaled into. That is, the internal pressure of the cylinder 25 becomes lower than the internal pressure of the suction chamber 57 due to the suction force of the piston 15 moving to the bottom dead center side, and accordingly the suction valve 36 is elastically deformed within the depth of the recess 26. As a result, the refrigerant CO ₂ from the evaporator 7 flows from the suction chamber 57 into the cylinder 25.

[0029] Further the piston 15 from this state reaches the bottom dead center in the cylinder 25, as shown in FIG. 2, clogging of the intermediate pressure intake opening 27 is released by the side of the piston 15, the pipe P ₇ The low-temperature refrigerant CO ₂ from the gas-liquid separator 5 that has flowed into the intermediate pressure suction chamber 60 via the intermediate pressure suction port 58 flows into the cylinder 25.
At this time, in the compressor 2, the refrigerant C from the evaporator 7
O ₂ and the low-temperature refrigerant CO ₂ from the gas-liquid separator 5 are mixed in the cylinder 25, so that the temperature of the refrigerant CO ₂ from the evaporator 7 decreases in the cylinder 25.

When the piston 15 moves to the top dead center side, the intermediate pressure suction opening 27 is closed by the side surface of the piston 15 and the refrigerant CO ₂ in the cylinder 25 is closed.
Is compressed by the piston 15. The compressed refrigerant CO ₂ in the cylinder 25 moves the discharge valve 42 to the retainer 44.
Is elastically deformed within the height range of the discharge chamber 34 and the discharge chamber 5.
Flow into 5. Further, the refrigerant CO ₂ is supplied to the gas cooler 3 via the pipe P ₁ and circulates in the refrigeration cycle 1 shown in FIG.

In the refrigeration cycle 1 using the compressor 2, the characteristics shown in the ph diagram (Mollier diagram) of FIG. 7 are obtained, and the COP can be improved while suppressing the discharge temperature of the refrigerant. It has become possible. In FIG. 7, the pressure of the pressure Ps in the evaporator 7, the pressure of the pressure Pd in the gas cooler 3, the pressure Pm respectively the pressure from the gas-liquid separator 5, the point P ₁ to P ₇ There is shown a state in the pipes P ₁ to P ₇ shown in FIG. In FIG. 7, the characteristics of the conventional compressor that does not suction the intermediate pressure from the gas-liquid separator 5 are indicated by broken lines.

[0032] That is, the compressor 2 of the present invention, as compared with the conventional compressor and the refrigerant discharge temperature is suppressed low in the pipe P _1, thereby the oil used in the compressor 2 (lubricant) Deterioration can be prevented. In the refrigerating cycle 1 using the compressor 2, the input W of the compressor 2 is different from the enthalpy value Ei of the evaporator 7 obtained by the multi-effect cycle in the value W1 when the conventional compressor is used. To W2. Therefore,
In the refrigeration cycle 1 using the compressor 2, the coefficient of performance COP
(= Ei / W), the input value of an external drive source such as an engine or a motor for rotating the drive shaft 14 becomes smaller, and it is possible to contribute to the prevention of global warming due to the elimination of CFCs.

In the above-described embodiment, an example is shown in which the present invention is applied to a compressor having six pistons, but the number of pistons is, of course, not limited to this. .

[0034]

As described above in detail, according to the reciprocating compressor of the present invention, when the piston moves toward the bottom dead center in the cylinder, the refrigerant from the outside receives the refrigerant suction passage and the valve of the cylinder head. When the piston flows into the cylinder through the mechanism and the piston reaches the bottom dead center, refrigerant from the outside flows into the cylinder through the intermediate pressure suction passage of the cylinder head and the intermediate pressure suction opening formed in the cylinder. Inflow,
At this time, since the refrigerant is mixed with the refrigerant flowing into the cylinder through the refrigerant suction passage and the valve mechanism, the low-temperature refrigerant is externally fed into the intermediate pressure suction passage, so that the cylinder is cooled through the refrigerant suction passage and the valve mechanism. The temperature of the refrigerant flowing into the compressor is reduced in the cylinder, and as a result, the refrigerant discharge temperature after compression is suppressed to a low level, and oil deterioration inside the compressor can be prevented.

In the CO ₂ cycle using the reciprocating compressor, the input value W of the reciprocating compressor is smaller than the enthalpy value Ei on the evaporator side obtained by the multi-effect cycle. COP (= Ei / W) is improved.

Therefore, according to the present invention, it is possible to provide a reciprocating compressor for a CO ₂ cycle capable of improving the COP of a refrigeration cycle while suppressing an increase in refrigerant discharge temperature.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a refrigeration cycle using a reciprocating compressor of the present invention.

FIG. 2 is a cross-sectional view taken along line AB, showing the configuration of the reciprocating compressor.

FIG. 3 is a perspective view from a cylinder head side showing a positional relationship between members such as a valve plate and a cylinder.

FIG. 4 is a perspective view of a cylinder block.

FIG. 5 is a plan view illustrating a configuration of a valve mechanism, and FIG.
Shows a valve plate, (B) shows a suction valve, and (C) shows a discharge valve.

FIG. 6 is a plan view showing an internal configuration of a cylinder head.

FIG. 7 is a ph diagram (Mollier diagram) in the refrigeration cycle.

FIG. 8 is a circuit configuration diagram of a conventional refrigeration cycle.

[Explanation of symbols]

1 refrigeration cycle 2 compressor 3 gas cooler 4 first expansion valve 5 the gas-liquid separator 6 second expansion valve 7 evaporator P ₁ to P ₇ pipe 11 front housing 12 a cylinder block 13 cylinder head 14 drive shaft 15 piston 18 swash plate Reference Signs List 19 swing plate 20 crank chamber 21 piston rod 25 cylinder 27 intermediate pressure suction opening 31 valve plate 33 suction hole 34 discharge hole 35 suction valve member 36 suction valve 41 discharge valve member 42 discharge valve 51 rising wall 52 peripheral edge 53 side wall Portion 54 Discharge port 55 Discharge chamber 56 Suction port 57 Suction chamber 58 Intermediate pressure suction port 60 Intermediate pressure suction chamber

Claims (1)

[Claims] 1. A front housing in which a drive shaft is rotatably held, a cylinder block connected to the front housing and having a cylinder in which a piston is stored, and a refrigerant connected to the cylinder block and communicating with the cylinder. A cylinder head having a passage formed therein, and a valve mechanism disposed between the cylinder block and the cylinder head, and a rotational driving force transmitted from an external drive source is applied to the piston via the drive shaft. In the reciprocating compressor, in which the external refrigerant is sucked in by the piston, compressed and circulated to the air conditioning system by transmitting the refrigerant, the refrigerant passage of the cylinder head is configured to transfer the external refrigerant to the cylinder of the cylinder block. A refrigerant suction passage for supplying a refrigerant through a valve mechanism, and a refrigerant compressed by a piston in the cylinder. A refrigerant discharge passage that discharges the refrigerant to the outside through the structure, and an intermediate pressure suction passage that sucks the refrigerant from the outside as an intermediate pressure. The cylinder block communicates with the intermediate pressure suction passage, and the intermediate pressure suction passage. A reciprocating compressor characterized in that an intermediate pressure suction opening for supplying intermediate pressure from a passage into the cylinder is formed at a position near a bottom dead center of the cylinder.