Patent Description:
In a compressor, if the compressor is overheated by a compressed gas having a high temperature and a high pressure, the density of a gas to be compressed sucked into the compressor decreases, causing a decrease in efficiency of the compressor. Therefore, for example, in a reciprocating compressor, as a means for suppressing overheating of the compressor, a pipe for flowing cooling water is provided inside a crankcase or a head cover. For example, Patent Document <NUM>, <NUM> discloses a configuration for suppressing overheating by injecting a refrigerant liquid into a discharge space in a head cover and cooling a compressed discharge gas with latent heat of vaporization of the refrigerant liquid. Other examples of compressors are described in <CIT>, <CIT>, and <CIT>.

According to the configuration disclosed in Patent Document <NUM>, <NUM>, it is possible to cool the discharge gas, and it is possible to suppress overheating of the compressor. However, due to an influence of cooling, a large amount of frost may occur on a surface of the compressor (for example, a surface of the head cover or the casing). Such configuration where the large amount of frost occurs is not preferable.

The present disclosure has been made in view of the above-described problems, and the object of the present disclosure is to suppresses the occurrence of frost on the surface of the compressor when the compressed discharge gas is cooled by injecting the refrigerant liquid into the discharge space of the compressor.

In order to achieve the above object, there is provided a compressor as defined in appended claim <NUM>. Other advantageous embodiments are defined in the corresponding dependent claims.

Further, there is provided a compressor system, as defined in claim <NUM>, including: a low-stage compression part; and a high-stage compression part. At least the low-stage compression part is constituted by the compressor as defined in the above.

Herein, the "low-stage compression part" and the "high-stage compression part" include a low-stage compressor and a high-stage compressor each having an independent casing, and a low-stage compressor and a high-stage compressor housed in a single housing casing, for example, a reciprocating compressor.

With the compressor and the compressor system according to the present disclosure, since the above-described heat medium flow path is provided, it is possible to increase the temperature of the compressor casing which includes the partition wall forming the discharge space, making it possible to suppress the occurrence of frost on the surface of the compressor.

Some embodiments of the present invention will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described or shown in the drawings as the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention, which is defined by the appended claims.

For instance, an expression of relative or absolute arrangement such as "in a direction", "along a direction", "parallel", "orthogonal", "centered", "concentric" and "coaxial" shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance whereby it is possible to achieve the same function.

For instance, an expression of an equal state such as "same", "equal", and "uniform" shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance that can still achieve the same function.

Further, for instance, an expression of a shape such as a rectangular shape or a tubular shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.

On the other hand, an expressions such as "comprising", "including", "having", "containing", and "constituting" one constitutional element are not intended to be exclusive of other constitutional elements.

<FIG> is a front cross-sectional view of a compressor <NUM> according to an embodiment, and <FIG> is a system diagram showing a lubricant oil supply system for the compressor <NUM> according to an embodiment. In <FIG> and <FIG>, the compressor <NUM> is, for example, a compressor incorporated in a refrigeration device or the like and configured to compress a refrigerant gas. The compressor <NUM> includes a discharge valve <NUM>, and a discharge space Sv is formed downstream of the discharge valve <NUM>. A liquid injection hole <NUM> for injecting the refrigerant liquid into the discharge space Sv is formed in a compressor casing <NUM>. In the present embodiment, as in Patent Documents <NUM> and <NUM>, a condensate liquid of the refrigerant gas, which is the gas to be compressed, is injected from the liquid injection hole <NUM> into the discharge space Sv. The condensate liquid evaporates in the high-temperature discharge space Sv, absorbs latent heat of vaporization from a discharge gas Gv, and cools the discharge gas Gv. Thus, it is possible to suppress overheating of the discharge gas Gv. However, as the case now stands, frost may occur on a surface of a casing <NUM> forming the discharge space Sv, as described above.

Therefore, in order to suppress the occurrence of frost on the casing <NUM>, the compressor <NUM> includes a heat medium flow path <NUM> located opposite to the discharge space Sv across a partition wall 18a forming the discharge space Sv. By flowing a heat medium through the heat medium flow path <NUM>, the temperature of the casing <NUM> including the partition wall 18a is increased, making it possible to suppress the occurrence of frost on the surface of the casing <NUM>.

In an embodiment, the compressor <NUM> includes a lubricant oil flow path <NUM> through which lubricant oil r supplied to a part to be lubricated flows. The heat medium flow path <NUM> is disposed in series or parallel with the lubricant oil flow path <NUM>. According to the present embodiment, since it is possible to cause the lubricant oil r, which has absorbed the heat of the part to be lubricated in the compressor <NUM> by lubricating and cooling the part to be lubricated, to flow through the heat medium flow path <NUM>, the temperature of the casing <NUM>, which includes the partition wall 18a forming the discharge space Sv, can be increased by potential heat of the lubricant oil r. Therefore, it is possible to suppress the occurrence of frost on the surface of the casing <NUM> of the compressor <NUM>. The part to be lubricated of the compressor <NUM> includes, as an example, at least either of a rotor or a rotor support portion. As a more specific example, the parts to be lubricated are a crank shaft <NUM> and a thrust bearing <NUM>, which will be described later. The part to be lubricated may be either the crank shaft <NUM> or the thrust bearing <NUM>.

In an embodiment, as shown in <FIG>, the heat medium flow path <NUM> is arranged in series with the lubricant oil flow path <NUM>, and a circulation path <NUM> for the lubricant oil r including the part to be lubricated of the compressor <NUM>, the heat medium flow path <NUM>, and the lubricant oil flow path <NUM> is formed. Further, the circulation path <NUM> is provided with an oil pump <NUM> for circulating the lubricant oil r. According to the present embodiment, since the lubricant oil r circulating in the circulation path <NUM> by the oil pump <NUM> is cooled in the heat medium flow path <NUM>, a dedicated oil cooler is not required and a cost can be reduced.

<FIG> shows an embodiment in which the heat medium flow path <NUM> is disposed in parallel with the circulation path <NUM>. In the present embodiment, an oil cooler <NUM> is provided in the circulation path <NUM> for the lubricant oil flowing through the part to be lubricated of the compressor <NUM>. The lubricant oil r flowing through the circulation path <NUM> flows through the part to be lubricated of the compressor <NUM>, cools the part to be lubricated, is heated, and is cooled by the oil cooler <NUM>. Further, the compressor <NUM> includes a branch path <NUM> branching off from the circulation path <NUM>, communicating with the heat medium flow path <NUM>, and merging with the circulation path <NUM> again. The lubricant oil r flowing through the branch path <NUM> exchanges heat with the discharge gas Gv in the heat medium flow path <NUM> to heat the discharge gas Gv. According to the present embodiment, since the discharge gas Gv is heated by the heat medium flow path <NUM>, it is possible to suppress frost generated on the partition wall 18a or the surface of the casing <NUM> including the partition wall 18a. Meanwhile, the oil cooler <NUM> plays the main role of cooling the lubricant oil r.

As shown in <FIG>, the circulation path <NUM> and the branch path <NUM> may be provided with flow control valves <NUM> and <NUM>, respectively. Only one of the flow control valve <NUM> and the flow control valve <NUM> may be provided. Since these flow control valves <NUM> and <NUM> are provided, it is possible to control the flow rate of the lubricant oil r flowing through the branch path <NUM>, making it possible to control the heating capacity of the heat medium flow path <NUM>. It is preferable that the branching portion and the merging portion of the branch path <NUM> with respect to the circulation path <NUM> are disposed such that the lubricant oil r having a temperature suitable for a heating condition of the heat medium flow path <NUM> flows through the heat medium flow path <NUM>.

In an embodiment, as shown in <FIG> and <FIG>, the compressor <NUM> is the reciprocating compressor. In this case, the compressor <NUM> is configured such that a cylinder <NUM> is housed inside the compressor casing <NUM> and a piston <NUM> reciprocates inside the cylinder <NUM>. A valve plate <NUM> for supporting the discharge valve <NUM> is disposed at one end of the cylinder <NUM> (an upper end of the cylinder <NUM> in the figure) and further, a head cover is provided as the casing <NUM> which includes the partition wall 18a forming the discharge space Sv. According to the compressor <NUM> which is the reciprocating compressor, the temperature of the head cover serving as the casing <NUM> can be increased by the heat medium flowing through the heat medium flow path <NUM>, making it possible to suppress the occurrence of frost on the surface of the head cover. In the present embodiment, the casing <NUM> of the compressor <NUM> is the head cover, but the casing <NUM> is not limited to the head cover. Hereinafter, the casing <NUM> may be called the head cover <NUM>.

Further, as shown in <FIG> and <FIG>, a crankcase <NUM> is disposed below the compressor casing <NUM>. The crank shaft <NUM> is supported by the crankcase <NUM> via the thrust bearing <NUM>. An oil reservoir Os of the lubricant oil r is formed at the bottom of the crankcase <NUM>. The piston <NUM> is connected to the crank shaft <NUM> via a connecting rod <NUM>, and the piston <NUM> reciprocates inside the cylinder <NUM> as the crank shaft <NUM> rotates. In the exemplary embodiments shown in <FIG> and <FIG>, two cylinders <NUM> are disposed in parallel, and the pistons <NUM> of the two cylinders <NUM> are connected to the crank shaft <NUM> so as to reciprocate in phases different by <NUM>° at a rotation angle of the crank shaft <NUM>. Further, a motor <NUM> for rotary driving the crank shaft <NUM> is disposed at one end of the crank shaft <NUM> outside the crankcase <NUM>. The oil pump <NUM> is disposed at another end of the crank shaft <NUM> and is operated by the rotation of the crank shaft <NUM>.

As shown in <FIG>, an oil filter <NUM> is disposed in the oil reservoir Os, and the oil pump <NUM> sucks up the lubricant oil r from the oil reservoir Os into the lubricant oil flow path <NUM>. A pressure regulating valve <NUM> disposed at a terminating end of the lubricant oil flow path <NUM> regulates an oil pressure of the lubricant oil r flowing through the circulation path <NUM>. The parts to be lubricated, such as the crank shaft <NUM> and the thrust bearing <NUM>, are formed with oil passages <NUM> and <NUM>. The lubricant oil r discharged from the oil pump <NUM> to the lubricant oil flow path <NUM> is supplied to these oil passages. As shown in <FIG>, a part of the oil passage <NUM> is introduced to the piston <NUM> via a crank pin <NUM>. Further, the lubricant oil r is supplied from the lubricant oil flow path <NUM> to the heat medium flow path <NUM> to heat the discharge gas Gv. The lubricant oil r that has passed through the heat medium flow path <NUM> returns to the oil reservoir Os via the oil passages <NUM> and <NUM>, or the like. Thus, the circulation path <NUM> for the lubricant oil r described above is formed.

As shown in <FIG>, the suction space Si is formed outside the cylinder <NUM>, and if the piston <NUM> descends and a compression space in the cylinder <NUM> is decompressed, the refrigerant gas, which is the gas to be compressed, is sucked from the suction space Si into a compression space in the cylinder <NUM> through a suction valve <NUM>. The refrigerant gas sucked into the compression space is compressed in the compression space and discharged to the discharge space Sv. A disc-shaped valve cage <NUM> is pressed and fixed to an upper surface of the valve plate <NUM> by a coil spring <NUM> to block an opening of the valve plate <NUM>. A truncated conical valve plate <NUM> is joined to a lower surface of the valve cage <NUM> by a bolt <NUM>. A discharge gas passage is formed in the valve cage <NUM> and the discharge valve <NUM> is mounted thereon. If the piston <NUM> rises and a gas pressure in a cylinder chamber increases, the discharge valve <NUM> is pushed up to discharge the refrigerant gas into the discharge gas passage.

In an embodiment, as shown in <FIG> and <FIG>, the compressor <NUM> includes a coolant flow path <NUM> for cooling the compressor driving motor <NUM>. The coolant flow path <NUM> communicates with the heat medium flow path <NUM>. In the present embodiment, a liquid coolant, which has cooled the motor <NUM> and sucked a potential heat of the motor <NUM>, is flowed through the heat medium flow path <NUM> and the casing <NUM>, which includes the partition wall 18a forming the discharge space Sv, can be increased in temperature by potential heat of the coolant, making it possible to suppress the occurrence of frost on the surface of the casing <NUM> of the compressor <NUM>.

Furthermore, as another embodiment, for example, heated hot water, an antifreeze liquid, or the like, which is used as a cooling liquid in another part of the compressor <NUM>, may be supplied to the heat medium flow path <NUM> to heat the discharge space Sv.

In an embodiment, as shown in <FIG>, a jacket cover <NUM> internally having a heat medium introduction space is disposed on an outer surface of the head cover serving as the casing <NUM>. The heat medium introduction space forms the heat medium flow path <NUM>. According to the present embodiment, the heat medium flow path <NUM> can be formed simply by mounting the jacket cover <NUM> on the existing compressor and the other parts do not need modification, making it possible to easily form the heat medium flow path <NUM>.

In the exemplary embodiment shown in <FIG>, the jacket cover <NUM> is formed with an inlet hole 74a and an outlet hole 74b of the heat medium flow path <NUM>, and the lubricant oil flow path <NUM> is connected to the inlet hole 74a and the outlet hole 74b. Then, the lubricant oil r is supplied from the inlet hole 74a to the heat medium introduction space (heat medium flow path <NUM>) and is discharged from the outlet hole 74b to the lubricant oil flow path <NUM>. As shown in <FIG>, the inlet hole 74a and the outlet hole 74b are, respectively, formed at both end portions of the jacket cover <NUM> away from each other. Thus, it is possible to increase a residence time of the lubricant oil r in the heat medium introduction space, and it is possible to improve the heat exchange rate with the discharge gas Gv.

In an embodiment, as shown in <FIG>, the liquid injection hole <NUM> for injecting the refrigerant liquid into the discharge space Sv includes a through hole 14a formed in the valve plate <NUM>, and a communication hole 14b disposed in a wall portion of the compressor casing <NUM> and communicating with the through hole 14a to cause the through hole 14a to communicate with an external space. As will be described later, in a heat pump device including the compressor <NUM>, the communication hole 14b is connected to a refrigerant path <NUM> branching off from an outlet-side refrigerant path of the liquid receiver <NUM>, and the refrigerant liquid is supplied from the refrigerant path <NUM> to the liquid injection hole <NUM>.

In an embodiment, as shown in <FIG>, one end of the through hole 14a is open to the discharge space Sv, and another end of the through hole 14a is formed so as to communicate with the communication hole 14b.

According to the present embodiment, the liquid injection hole <NUM> can be formed at a position avoiding the head cover <NUM>. If the heat medium flow path <NUM> needs to be disposed on the head cover <NUM> side and the liquid injection hole <NUM> is disposed on the head cover <NUM> side, the installation positions of the heat medium flow path <NUM> and the liquid injection hole <NUM> interfere. In the present embodiment, since the liquid injection hole <NUM> can be formed at the position on the valve plate <NUM> side avoiding the head cover <NUM>, it is possible to realize a layout of the liquid injection hole <NUM> that can avoid the interference with the heat medium flow path <NUM>.

In the exemplary embodiment shown in <FIG>, the communication hole 14b is formed in an upper end portion of the casing surrounding the cylinder <NUM>, which is a part of the compressor casing <NUM>. On the other hand, the communication hole 14b may be formed in the valve plate <NUM>. Further, the installation position of the liquid injection hole <NUM> is not limited to that of the above embodiment, and may be formed in another position, for example, in the head cover <NUM>.

In an embodiment, as shown in <FIG>, an outer peripheral edge portion of the valve plate <NUM> is interposed between the compressor casing <NUM> and an outer peripheral edge portion of the head cover <NUM>. If the outer peripheral edge portion of the valve plate <NUM> is thus disposed in such a manner as to be exposed to the external space of the compressor <NUM>, processing for opening the liquid injection hole <NUM> to the external space of the compressor <NUM> is facilitated. Further, as shown in <FIG>, since the outer peripheral edge portions of the compressor casing <NUM>, the valve plate <NUM>, and the head cover <NUM> are laminated in three layers, the outer peripheral edge portions of these three layers can easily be joined by fastening together with a bolt <NUM>. Thus, the valve plate <NUM> is mounted easily.

In an embodiment, a compressor system <NUM> shown in <FIG> is a two-stage compressor system which includes a low-stage compressor <NUM> and a high-stage compressor <NUM>, and in which the refrigerant gas is the gas to be compressed, and the low-stage compressor <NUM> is constituted by the compressor <NUM> according to the above embodiment. Since the low-stage compressor <NUM> is constituted by the compressor <NUM>, it is possible to suppress the occurrence of frost on the surface of the casing <NUM>, which includes the partition wall forming the discharge space, in the low-stage compressor <NUM>.

In the exemplary compressor system <NUM> shown in <FIG>, the low-stage compressor <NUM> and the high-stage compressor <NUM> are each constituted by the reciprocating compressor. A liquid receiver <NUM> is disposed on a refrigerant circulation path <NUM>, and the refrigerant liquid in the liquid receiver <NUM> is decompressed by an expansion valve <NUM> through the refrigerant circulation path <NUM>, and evaporates by absorbing latent heat of vaporization from a load in an evaporator <NUM>. The refrigerant gas evaporated in the evaporator <NUM> is sucked into a suction chamber <NUM> of the low-stage compressor <NUM>, is further sucked into a cylinder <NUM> via a suction valve <NUM>, and is compressed.

The refrigerant gas compressed by the cylinder <NUM> is discharged to a discharge chamber <NUM> via a discharge valve <NUM> and discharged from the discharge chamber <NUM> to the refrigerant circulation path <NUM>. The refrigerant gas discharged to the refrigerant circulation path <NUM> is sucked into the suction chamber <NUM> of the high-stage compressor <NUM> after the lubricant oil is separated by an oil separator <NUM>. The refrigerant gas sucked into the suction chamber <NUM> of the high-stage compressor <NUM> is further sucked into the cylinder <NUM> via the suction valve <NUM>, is compressed, and is discharged from the discharge chamber <NUM> to the refrigerant circulation path <NUM>. The refrigerant gas discharged to the refrigerant circulation path <NUM> is cooled and liquefied by the condenser <NUM> after the lubricant oil is separated by the oil separator <NUM>.

A branch path <NUM> branching off from the refrigerant circulation path <NUM> is disposed downstream of the liquid receiver <NUM>, and the branch path <NUM> is provided with a liquid pump <NUM> and a pressure regulating valve <NUM>. The branch path <NUM> is connected to the discharge chamber <NUM> of the high-stage compressor <NUM>, and the refrigerant liquid is pressurized to have a higher pressure than the discharge chamber <NUM> of the high-stage compressor <NUM> by controlling a rotation speed of the oil pump <NUM> and the pressure control with the pressure regulating valve <NUM>, and is injected into the discharge chamber <NUM> from an injection nozzle <NUM> disposed in the discharge chamber <NUM>. The injected refrigerant liquid evaporates under the temperature and pressure conditions of the discharge chamber <NUM> to cool the discharge space.

Further, the refrigerant circulation path <NUM> is provided with a branch path <NUM> branching off from the refrigerant circulation path <NUM> at a downstream position of the branch path <NUM>. The branch path <NUM> is connected to the injection nozzle <NUM> disposed on an inner wall surface of the discharge chamber <NUM> of the low-stage compressor <NUM>. Since the discharge chamber <NUM> of the low-stage compressor <NUM> has the lower pressure than the branch path <NUM>, the refrigerant liquid can be supplied to the discharge chamber <NUM> at the same pressure without increasing the pressure. The discharge chamber <NUM> of the low-stage compressor <NUM> is cooled by evaporation of the refrigerant liquid injected from the injection nozzle <NUM> under the temperature and pressure conditions of the discharge chamber <NUM>. In the present embodiment, since the low-stage compressor <NUM> is constituted by the compressor <NUM> according to each of the above-described embodiments, it is possible to suppress frost generated on the surface of the casing (head cover) <NUM> of the compressor <NUM>.

In the compressor system <NUM> shown in <FIG>, the low-stage compressor <NUM> and the high-stage compressor <NUM> may constitute a single-machine two-stage compressor in which the low-stage compressor and the high-stage compressor are housed in one casing. For example, in the compressor <NUM> shown in <FIG>, a compressor system may be configured in which one cylinder <NUM> is the low-stage compressor and the another cylinder is the high-stage compressor.

The contents described in the present application would be understood as follows, for instance.

Claim 1:
A compressor (<NUM>), comprising:
a compressor casing (<NUM>);
a discharge valve (<NUM>);
a discharge space (Sv) formed downstream of the discharge valve; and
a liquid injection hole (<NUM>) for injecting a refrigerant liquid into the discharge space, and a heat medium flow path (<NUM>) located opposite to the discharge space across a partition wall (18a) forming the discharge space,
characterized in that the heat medium flow path is configured to increase the temperature of the compressor casing which includes the partition wall forming the discharge space, making it possible to suppress an occurrence of frost on a surface of the compressor.