Patent Description:
A reciprocating compressor generally includes a suction gas passage and a discharge gas passage in a casing. Therefore, a high-temperature discharge gas and a low-temperature suction gas may exchange heat via s wall surface of the casing, and a temperature of the suction gas may increase before the suction gas is sucked into the cylinder. Consequently, the suction gas may expand before being sucked into the cylinder and increase in specific volume, and the mass flow rate of the discharge gas may decrease to an unignorable extent. Therefore, volumetric efficiency is decreased in the compressor, and refrigeration capacity may be decreased if the reciprocating compressor is incorporated in a refrigeration system.

Therefore, as means for suppressing overheating of the compressor, for example, a pipe for flowing cooling water is provided inside a crankcase or a head cover. Patent Document <NUM>, <NUM> discloses a configuration for suppressing overheating of a suction gas 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 disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>.

According to the configuration disclosed in Patent Document <NUM>, <NUM>, it is possible to suppress overheating of the suction gas by cooling the discharge gas. However, due to an influence of cooling of the discharge gas, 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 an object of the present disclosure is to suppresses heat input from a discharge space to a suction space and to prevent a decrease in volumetric efficiency of the compressor due to the heat input from the discharge space to the suction space while reducing a risk that frost adheres to the surface 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 the corresponding claim, the compressor system including: the above-described compressor; a refrigerant circulation path communicating with the suction space and the discharge space of the compressor; a condenser for condensing a discharge gas discharged from the discharge space; and a branch path branching off from the refrigerant circulation path downstream of the condenser and communicating with the cooling medium path.

With a compressor according to the present disclosure, since a cooling medium is supplied to a cooling medium path formed in a partition wall portion separating a suction space and a discharge space, it is possible to suppresses heat input from the discharge space to the suction space and to prevent a decrease in volumetric efficiency of the compressor due to the heat input from the discharge space to the suction space while reducing a risk that frost adheres to a compressor surface. Further, in addition to the above-described technical effects, if the compressor system according to the present disclosure is applied to a refrigeration system or a heat pump system, it is possible to suppress a decrease in COP.

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 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 or a difference 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> and <FIG> are front cross-sectional views of a compressor <NUM> (10A, 10B) according to some embodiments and <FIG> is a front cross-sectional view of a compressor <NUM> (10C) according to an example (not claimed). In <FIG>, the compressor <NUM> (10A to 10C) includes a cylinder <NUM> and a piston <NUM> configured to be reciprocable in the cylinder <NUM>, and the cylinder <NUM> and the piston <NUM> form a working chamber Sc. The compressor <NUM> (10A to 10C) also includes a suction space Si and a discharge space Sv each of which can communicate with the working chamber Sc. Further, a partition wall portion <NUM> is disposed so as to surround the working chamber Sc, and the partition wall portion <NUM> separates the suction space Si and the discharge space Sv. The partition wall portion <NUM> is provided with a suction valve <NUM> for switching a state of communication between the suction space Si and the working chamber Sc, and a discharge valve <NUM> for switching a state of communication between the discharge space Sv and the working chamber Sc, and a cooling medium path <NUM> for flowing a cooling medium is formed.

In the above-described embodiment and the example (not claimed), the suction gas that has been sucked into the suction space Si is sucked into the working chamber Sc through a passage opened and closed by the suction valve <NUM>, and is compressed by the piston <NUM>. The suction gas that has been compressed to high temperature and high pressure is discharged to the discharge space Sv through a passage opened and closed by the discharge valve <NUM>. By flowing the cooling medium through the cooling medium path <NUM> formed in the partition wall portion <NUM> separating the suction space Si and the discharge space Sv, heat input from the discharge space Sv to the suction space Si can be deterred, making it possible to suppress a decrease in volumetric efficiency of the compressor <NUM> due to the heat input from the discharge space Sv to the suction space Si. On the other hand, since the partition wall portion <NUM> disposed in the compressor <NUM> is away from the compressor surface, a decrease in temperature on the compressor surface is suppressed. Therefore, it is possible to suppress occurrence of frost on the compressor surface.

The embodiments shown in <FIG> and <FIG> and the example (not claimed) shown in <FIG> constitute a so-called reciprocating compressor. A crank shaft <NUM> is disposed at the bottom, and the piston <NUM> is connected to the crank shaft <NUM> via a connecting rod <NUM>. With a rotation of the crank shaft <NUM>, the piston <NUM> reciprocates in the cylinder <NUM>. In the exemplary reciprocating compressor shown in <FIG>, two cylinders <NUM> are disposed parallel to the crank shaft <NUM>, and each piston <NUM> is connected to the crank shaft <NUM> so as to reciprocate at phase angles different by <NUM>°. An upper surface of the cylinder <NUM> is closed by a valve cage <NUM>, and a head cover <NUM> for forming the discharge space Sv is provided above the partition wall portion <NUM>. The head cover <NUM> is formed with an opening 46a for delivering the discharge gas.

As the cooling medium supplied to the cooling medium path <NUM>, for example, cooling water, an antifreeze liquid, or the like can be used. Further, if the compressor <NUM> is incorporated in a refrigeration system or a heat pump system, a refrigerant liquid can be used as a working fluid for these systems.

In an embodiment, as shown in <FIG> and <FIG>, the partition wall portion <NUM> includes a valve plate <NUM> for holding the suction valve <NUM> and the discharge valve <NUM>, and the cooling medium path <NUM> is formed in the valve plate <NUM>. The valve plate <NUM> is cooled by flowing the cooling medium through the cooling medium path <NUM>, making it possible to deter the heat input from the discharge space Sv to the suction space Si. Thus, it is possible to suppress the decrease in volumetric efficiency of the compressor <NUM> due to the heat input from the discharge space Sv to the suction space Si. On the other hand, since the discharge space Sv or the like is interposed between the valve plate <NUM> and the compressor surface (for example, the surface of the head cover <NUM>), the decrease in temperature on the compressor surface (for example, the surface of the head cover <NUM>) is suppressed. Therefore, it is possible to suppress occurrence of frost on the compressor surface.

In an embodiment, as shown in <FIG> and <FIG> and in an example, as shown in <FIG>, the compressor <NUM> (10A to 10C) includes a compressor casing <NUM> for containing the suction space Si, and housing the cylinder <NUM> and the piston <NUM>. In the embodiments shown in <FIG> and <FIG>, the valve plate <NUM> is formed with a first channel groove <NUM> having an opening 31a on a compressor casing <NUM> side, and the cooling medium path <NUM> is constituted by the first channel groove <NUM>.

According to the present embodiment, since the cooling medium path <NUM> is constituted by the first channel groove <NUM>, there is no need to form a deep hole in the valve plate <NUM>, and the cooling medium path <NUM> can be formed by being cut from the surface of the valve plate <NUM>. This facilitates processing for forming the cooling medium path <NUM> in the valve plate <NUM>. Further, since the first channel groove <NUM> has the opening 31a on the compressor casing <NUM> side, the suction space Si can be cooled with the cooling medium flowing through the cooling medium path <NUM>.

In an embodiment, the first channel groove <NUM> is formed into a circular shape so as to surround the circumference of the cylinder <NUM>. In the exemplary embodiment shown in <FIG>, an outer peripheral edge portion of valve plate <NUM> is exposed to the outside of the head cover <NUM>. The cooling medium path <NUM> has a through hole <NUM> opening to an end face of the peripheral edge portion, and is mounted with an injection nozzle <NUM> for injecting the cooling medium to the through hole <NUM>. Further, a supply pipe <NUM> for supplying the cooling medium to the injection nozzle <NUM> is connected. The valve plate <NUM> can uniformly be cooled with the cooling medium sprayed from the injection nozzle <NUM>. Moreover, on an opposite side of a compressor body and a supply side of the cooling medium, a communication path <NUM> communicating with the cooling medium path <NUM> and the discharge space Sv is formed in a partition wall of the valve plate <NUM>, and the cooling medium is discharged to the discharge space Sv through the communication path <NUM>.

In the exemplary embodiment shown in <FIG>, a wall portion of the compressor casing <NUM> is formed with a supply path <NUM> for supplying the cooling medium to the first channel groove <NUM>, and the supply path <NUM> is connected to a supply pipe <NUM> for supplying the cooling medium. By thus forming the supply path <NUM> in the wall portion of the compressor casing <NUM>, the supply path for supplying the cooling medium to the first channel groove <NUM> is formed easily. Further, a throttle <NUM> is provided at an outlet where the cooling medium supplied from the supply pipe <NUM> to the supply path <NUM> opens to the cooling medium path <NUM>. The cooling medium turns into mist by passing through the throttle <NUM> and is sprayed to the cooling medium path <NUM>. The throttle <NUM> is composed of, for example, a plug which has a plurality of small-diameter through holes communicating with the supply path <NUM> and the cooling medium path <NUM>. In another embodiment, instead of providing the throttle <NUM>, an outlet opening diameter of the supply path <NUM> may be decreased to function as a throttle. On the other hand, in the compressor casing <NUM> on the opposite side of the compressor body with respect to the supply path <NUM>, a discharge path <NUM> for discharging the cooling medium after being used for cooling from the first channel groove <NUM> is formed, and a refrigerant discharge path <NUM> is connected to an outer opening of the discharge path <NUM>.

In the compressor <NUM> (10B) shown in <FIG>, even if the head cover <NUM> needs to be removed for maintenance, the supply pipe <NUM> need not be removed from the compressor casing <NUM>, facilitating maintenance work.

In the exemplary embodiments shown in <FIG> and <FIG>, and in the example (not claimed) shown in <FIG>, the compressor casing <NUM> doubles as a crankcase, and the crank shaft <NUM> is housed inside the compressor casing <NUM>.

In an embodiment, a heat-insulating gasket may be inserted into a laminated portion of the valve plate <NUM> and the compressor casing <NUM>. In this case, however, if the gasket is disposed in an area of the first channel groove <NUM>, a cooling effect of the suction gas flowing through the suction space Si is inhibited, and thus the gasket should not be disposed in the opening 31a.

In an example (not claimed), as shown in <FIG>, a second channel groove <NUM> is formed in a surface of the compressor casing <NUM> on the valve plate <NUM> side, and the cooling medium path <NUM> is constituted by the second channel groove <NUM>. According to the present example, the partition wall portion <NUM> including the valve plate <NUM> can be cooled by flowing the cooling medium through the cooling medium path <NUM>, making it possible to deter the heat input from the discharge space Sv to the suction space Si. Thus, it is possible to suppress the decrease in volumetric efficiency of the compressor <NUM> due to the heat input from the discharge space Sv to the suction space Si. On the other hand, even if the cooling medium is flowed through the cooling medium path <NUM>, since the discharge space Sv or the like is interposed between the valve plate <NUM> and the compressor surface, the decrease in temperature on the compressor surface (for example, the surface of the head cover <NUM>) is suppressed. Therefore, it is possible to suppress occurrence of frost on the compressor surface. Further, since the cooling medium path <NUM> can be formed by cutting the surface of the compressor casing <NUM>, the cooling medium path <NUM> is formed easily.

In an example (not claimed), as shown in <FIG>, in order to supply the cooling medium to the second channel groove <NUM>, the supply path <NUM> is formed in the compressor casing <NUM> and the supply pipe <NUM> is connected to an outer opening of the supply path <NUM>. On the other hand, in the compressor casing <NUM> on the opposite side of the compressor body with respect to the supply path <NUM>, a discharge path <NUM> for discharging the cooling medium after being used for cooling from the second channel groove <NUM> is formed, and a refrigerant discharge path <NUM> is connected to an outer opening of the discharge path <NUM>.

In an example (not claimed), as shown in <FIG>, a heat-insulating gasket <NUM> is interposed on an abutment surface between the valve plate <NUM> and the compressor casing <NUM> abutting each other. The heat-insulating gasket <NUM> is interposed, for example, on the entire abutment surface between the valve plate <NUM> and the compressor casing <NUM>, including a region where the second channel groove <NUM> is formed. By providing the heat-insulating gasket <NUM>, it is possible to effectively suppress the heat input from the discharge space Sv to the suction space Si existing inside the compressor casing <NUM>.

In an embodiment, as shown in <FIG> and in an example (not claimed), as shown in <FIG>, the outer peripheral edge portion of the valve plate <NUM> is interposed between an outer peripheral edge portion of the compressor casing <NUM> and an outer peripheral edge portion of the head cover <NUM>. Thus, the outer peripheral edge portions of the three layers, namely, the head cover <NUM>, the valve plate <NUM>, and the compressor casing <NUM> are fastened together with fasteners such as bolts, making it easier to mount the valve plate <NUM> on the compressor body. Further, in the embodiment shown in <FIG>, an end face of the outer peripheral edge portion of the valve plate <NUM> is exposed to the outside of the compressor <NUM>, making it easier to dispose the injection nozzle <NUM> at the opening of the through hole <NUM> communicating with the cooling medium path <NUM>.

In the exemplary embodiments shown in <FIG> and in the example (not claimed) shown in <FIG>, the outer peripheral edge portions of the head cover <NUM>, the valve plate <NUM>, and the compressor casing <NUM> are fastened together with bolts <NUM>. In the compressor <NUM> (10B) shown in <FIG>, the outer peripheral edge portion of the head cover <NUM> and the outer peripheral edge portion of the compressor casing <NUM> are connected with bolts <NUM>, and the outer peripheral edge portion of the valve plate <NUM> is disposed on the inner side of the head cover <NUM>.

<FIG> and <FIG> are system diagrams showing a compressor system <NUM> (70A, 70B) according to some embodiments. A refrigerant circulation path <NUM> of the compressor system <NUM> (70A, 70B) is provided with the compressor <NUM> (10A to 10C) according to the above-described embodiments and the example (not claimed). The compressor system <NUM> includes the refrigerant circulation path <NUM> communicating with the suction space Si and the discharge space Sv of the compressor <NUM>. The refrigerant circulation path <NUM> includes a condenser <NUM> for condensing a refrigerant gas discharged from the discharge space Sv, and a branch path <NUM> branching off from the refrigerant circulation path <NUM> downstream of the condenser <NUM> and communicating with the cooling medium path <NUM>.

The compressor system <NUM> (70A, 70B) constitutes a refrigeration system. The refrigerant gas discharged from the discharge space Sv is cooled by the condenser <NUM> and liquefied, and most of the liquefied refrigerant is decompressed by an expansion valve <NUM> disposed on the refrigerant circulation path <NUM> and is evaporated by an evaporator <NUM> to cool a load medium w. The refrigerant gas vaporized by the evaporator <NUM> is sucked into a suction chamber <NUM> forming the suction space Si of the compressor <NUM>. The refrigerant gas sucked into the suction chamber <NUM> is pressurized by the compressor <NUM> and discharged to the refrigerant circulation path <NUM> via a discharge chamber <NUM> forming the discharge space Sv. The branch path <NUM> branching off from the refrigerant circulation path <NUM> is disposed downstream of the condenser <NUM>. The branch path <NUM> communicates with the cooling medium path <NUM> formed in the partition wall portion <NUM> of the compressor <NUM>. Apart of the refrigerant liquid flowing through the refrigerant circulation path <NUM> is supplied to the cooling medium path <NUM> via the branch path <NUM> to cool the partition wall portion <NUM>.

In the exemplary embodiments shown in <FIG> and <FIG>, provided are an oil separator <NUM> for separating refrigerator oil from the refrigerant gas discharged from the compressor <NUM>, and a liquid receiver <NUM> for temporarily storing the refrigerant liquid condensed in the condenser <NUM>. Further, the compressor <NUM> is constituted by the reciprocating compressor.

The branch path <NUM> of the compressor system <NUM> (70A) shown in <FIG> is provided with a liquid pump <NUM>. If the compressor <NUM> (10A) shown in <FIG> is used in the compressor system <NUM> (70A), the branch path <NUM> and the discharge space Sv have the same pressure, requiring the liquid pump <NUM> in order to supply the refrigerant liquid from the branch path <NUM> to the cooling medium path <NUM>. By pressurizing the refrigerant liquid flowing through the branch path <NUM> with the liquid pump <NUM>, the refrigerant liquid can be supplied to the cooling medium path <NUM>. By providing a pressure regulating valve <NUM> downstream of the liquid pump <NUM> as necessary, it is possible to regulate the pressure of the refrigerant liquid flowing through the branch path <NUM>. The refrigerant liquid, which has flowed into the cooling medium path <NUM> having a lower pressure than the branch path <NUM>, evaporates under low pressure and absorbs heat of evaporation from the surroundings, making it possible to cool the partition wall portion <NUM>.

Thus, it is possible to suppress the heat input from the discharge space Sv to the suction space Si, and it is possible to suppress the decrease in volumetric efficiency of the compressor <NUM> due to the above-described heat input. Further, if the compressor <NUM> is applied to the refrigeration system or a heat pump system like the compressor system <NUM> (70A, 70B), it is possible to suppress a decrease in COP of these systems. Furthermore, the discharge space Sv or the like is interposed between the partition wall portion <NUM> and the compressor surface (for example, the surface of the head cover <NUM>) and the partition wall portion <NUM> is away from the compressor surface, suppressing the decrease in temperature on the compressor surface (for example, the surface of the head cover <NUM>). Therefore, it is possible to suppress occurrence of frost on the compressor surface.

Since the compressor system <NUM> (70A) shown in <FIG> includes the liquid pump <NUM>, if the compressor <NUM> (10B) shown in <FIG> or the compressor <NUM> (10C) shown in <FIG> is used as the compressor <NUM>, the refrigerant discharge path <NUM> or <NUM> can be connected to any location in the refrigerant circulation path <NUM> by appropriately setting a pressurizing force of the liquid pump <NUM>. Preferably, by connecting the refrigerant discharge path <NUM> or <NUM> to the refrigerant circulation path <NUM> upstream of the condenser <NUM> (for example, the refrigerant circulation path <NUM> between the oil separator <NUM> and the condenser <NUM>), it is not necessary to return the refrigerant that has been used to cool the partition wall portion <NUM> to the refrigerant circulation path <NUM> on the downstream side of the expansion valve <NUM>. Therefore, the supply of the refrigerant to the cooling medium path <NUM> does not lower performance of the compressor <NUM>. Since the injection is from the high-pressure liquid and the amount of the refrigerant is small, an influence of the power increase by the liquid pump is small.

The compressor system <NUM> (70B) shown in <FIG> is an embodiment in which the compressor <NUM> (10B) shown in <FIG> is used as the compressor <NUM>. In the present embodiment, the branch path <NUM> is not provided with the liquid pump <NUM>, and the refrigerant discharge path <NUM> or <NUM> is connected to the refrigerant circulation path <NUM> between the expansion valve <NUM> and the compressor <NUM> (10B). Since the refrigerant circulation path <NUM> in this area has the lower pressure than the branch path <NUM>, even if the branch path <NUM> is not provided with the liquid pump <NUM>, the refrigerant liquid supplied from the branch path <NUM> to the cooling medium path <NUM> can be discharged to the refrigerant circulation path <NUM> in this area via the refrigerant discharge path <NUM> or <NUM>. Occurrence of liquid back can be prevented by performing control such that the refrigerant liquid is completely vaporized in the cooling medium path.

The compressor system <NUM> (70C, 70D) shown in <FIG> and <FIG> includes a low-stage compressor 10a and a high-stage compressor 10b disposed in series on the refrigerant circulation path <NUM>. The refrigerant gas discharged from the discharge chamber <NUM> of the low-stage compressor 10a is supplied to the suction chamber <NUM> of the high-stage compressor 10b through the refrigerant circulation path <NUM> (intermediate path <NUM> (72a)) disposed between the low-stage compressor 10a and the high-stage compressor 10b. The refrigerant gas supplied to the suction chamber <NUM> of the high-stage compressor 10b is further compressed and is discharged from the discharge chamber <NUM> to the refrigerant circulation path <NUM>.

The compressor system <NUM> (70C, 70D) shown in <FIG> and <FIG> constitutes the refrigeration system, and the refrigerant decompressed by the expansion valve <NUM> is evaporated by the evaporator <NUM> and removes latent heat of vaporization from the load medium w to cool the load medium w. In the exemplary embodiments shown in <FIG> and <FIG>, two oil separators <NUM> for separating the refrigerator oil from the refrigerant gas discharged from the compressor <NUM> (the low-stage compressor 10a and the high-stage compressor 10b), and the liquid receiver <NUM> for temporarily storing the refrigerant liquid condensed in the condenser <NUM>. Further, the low-stage compressor 10a and the high-stage compressor 10b are each constituted by the reciprocating compressor.

In the embodiment where the partition wall portion <NUM> of the low-stage compressor 10a is cooled, a branch path 76a is provided which branches off from the refrigerant circulation path <NUM> on the downstream side of the condenser <NUM> and on the upstream side of the expansion valve <NUM> and communicates with the cooling medium path <NUM> of the low-stage compressor 10a. The compressor <NUM> (10A to 10C) shown in <FIG> can be used as the low-stage compressor 10a. When the compressor <NUM> (10B, 10C) is used, a refrigerant discharge path 42a or 60a is connected to the intermediate path <NUM> (72a). The intermediate path <NUM> (72a) has a lower pressure than the branch path 76a. Therefore, due to a differential pressure between the branch path 76a and the intermediate path <NUM> (72a), the refrigerant liquid diverted from the refrigerant circulation path <NUM> to the branch path 76a is discharged to the intermediate path <NUM> (72a) via the cooling medium path <NUM> and the communication path <NUM> in the case of the compressor <NUM> (10A), and is discharged to the intermediate path <NUM> (72a) via the cooling medium path <NUM> and the refrigerant discharge path 42a or 60a in the case of the compressor <NUM> (10B, 10C).

Among the embodiments where the partition wall portion <NUM> of the high-stage compressor 10b is cooled, in the embodiment shown in <FIG>, a branch path 76b is provided which branches off from the refrigerant circulation path <NUM> on the downstream side of the condenser <NUM> and on the upstream side of the expansion valve <NUM> and communicates with the refrigerant circulation path <NUM> of the high-stage compressor 10b. The compressor <NUM> (10A to 10C) shown in <FIG> can be used as the high-stage compressor 10b. The branch path 76b is provided with the liquid pump <NUM> and, if necessary, the pressure regulating valve <NUM>. When the compressor <NUM> (10B, 10C) is used, a refrigerant discharge path 42b or 60b, through which the refrigerant after cooling the partition wall portion <NUM> in the cooling medium path <NUM> is discharged, is connected to any location in the refrigerant circulation path <NUM>. The refrigerant liquid diverted from the refrigerant circulation path <NUM> to the branch path <NUM> is pressurized by the liquid pump <NUM>, and thus can be supplied to the cooling medium path <NUM> of the high-stage compressor 10b. The refrigerant after cooling the partition wall portion <NUM> is returned to the refrigerant circulation path <NUM> via the refrigerant discharge path 42b or 60b.

Preferably, the refrigerant discharge path 42b or 60b is connected to the refrigerant circulation path <NUM> on the upstream side of the condenser <NUM> (for example, the refrigerant circulation path <NUM> between the oil separator <NUM> and the condenser <NUM>). Thus, it is not necessary to return the refrigerant that has been used to cool the partition wall portion <NUM> to the intermediate path <NUM> (72a) or the refrigerant circulation path <NUM> on the downstream side of the expansion valve <NUM>. Therefore, the supply of the refrigerant to the cooling medium path <NUM> does not lower performance of the compressor.

Among the embodiments where the partition wall portion <NUM> of the high-stage compressor 10b is cooled, in the embodiment shown in <FIG>, the liquid pump <NUM> and the pressure regulating valve <NUM> need not be disposed on the branch path 76b. Instead, the refrigerant discharge path 42b or 60b is connected to the intermediate path <NUM> (72a). Since the pressure of the intermediate path <NUM> (72a) is lower than the pressure of the branch path 76b, the refrigerant supplied from the branch path 76b to the cooling medium path <NUM> can smoothly be discharged to the intermediate path <NUM> (72a) via the refrigerant discharge path 42b or 60b.

In the embodiments shown in <FIG> and <FIG>, both the low-stage compressor 10a and the high-stage compressor 10b include means for cooling the compressors. However, only either of the low-stage compressor 10a or the high-stage compressor 10b may include the cooling means.

Further, in another embodiment, the compressor system <NUM> can be applied to a single-machine two-stage compressor. When the compressor system <NUM> is applied to the refrigeration system, it is the cooling effect of the low-stage compressor that most influences the refrigeration capacity. The single-machine two-stage compressor includes a low-stage compressor and a high-stage compressor housed in one casing. Therefore, the low-stage compressor is susceptible to a temperature increase by the high-stage compressor. By applying the compressor system <NUM> to the single-machine two-stage compressor, the refrigeration capacity can be maintained high.

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

With such configuration, by forming the cooling medium path in the partition wall portion separating the suction space and the discharge space and flowing the cooling medium through the cooling medium path, heat input from the discharge space to the suction space can be deterred, making it possible to suppress a decrease in volumetric efficiency of the compressor due to the heat input from the discharge space to the suction space. On the other hand, since the partition wall portion disposed in the compressor is away from the compressor surface, a decrease in temperature on the compressor surface (for example, the surface of the head cover <NUM>) is suppressed. Therefore, it is possible to suppress occurrence of frost on the compressor surface.

<NUM>) A compressor (<NUM>) according to another aspect is the compressor (<NUM>) as defined in <NUM>), including: a suction valve (<NUM>) for switching a state of communication between the suction space (Si) and the working chamber (Sc); a discharge valve (<NUM>) for switching a state of communication between the discharge space (Sv) and the working chamber; and a valve plate (<NUM>) for holding the suction valve and the discharge valve. The cooling medium path (<NUM>) is formed in the valve plate serving as the partition wall portion (<NUM>).

With such configuration, by forming the cooling medium path in the above-described valve plate and cooling the cooling medium path, the heat input from the discharge space to the suction space can be deterred, making it possible to suppress the decrease in volumetric efficiency of the compressor due to the heat input from the discharge space to the suction space. On the other hand, since the valve plate disposed in the compressor is away from the compressor surface, the decrease in temperature on the compressor surface (for example, the surface of the head cover <NUM>) is suppressed. Therefore, it is possible to suppress occurrence of frost on the compressor surface.

<NUM>) The compressor (<NUM>) according to still another aspect is the compressor as defined in <NUM>), including: a compressor casing (<NUM>) for including the suction space (Si), and housing the cylinder (<NUM>) and the piston (<NUM>). The valve plate (<NUM>) is formed with a first channel groove (<NUM>) in a surface on a side of the compressor casing. At least a part of the cooling medium path (<NUM>) is formed by the first channel groove.

With such configuration, since the at least part of the cooling medium path is formed by the above-described first channel groove, it is not necessary to form a deep hole in the valve plate when the cooling medium path is formed in the valve plate. This facilitates processing for forming the cooling medium path. Further, since the first channel groove has the opening on the compressor casing side, the suction space can be cooled with the cooling medium flowing through the cooling medium path.

<NUM>) A compressor (<NUM>) according to yet another aspect is the compressor as defined in <NUM>), including: a suction valve (<NUM>) for switching a state of communication between the suction space (Si) and the working chamber (Sc); a discharge valve (<NUM>) for switching a state of communication between the discharge space (Sv) and the working chamber; a valve plate (<NUM>) for holding the suction valve and the discharge valve; and a compressor casing (<NUM>) for housing the cylinder and the piston. The compressor casing is formed with a second channel groove (<NUM>) in a surface on a side of the valve plate. At least a part of the cooling medium path (<NUM>) is formed by the second channel groove.

With such configuration, since the above-described cooling medium path can be formed by cutting the surface of the compressor casing, the cooling medium path is formed easily.

<NUM>) A compressor (<NUM>) according to yet another aspect is the compressor as defined in <NUM>), including: a heat-insulating gasket (<NUM>) interposed on an abutment surface between the valve plate (<NUM>) and the compressor casing (<NUM>).

With such configuration, by providing the above-described heat-insulating gasket, it is possible to further suppress the heat input from the discharge space to the suction space disposed on the compressor casing side.

<NUM>) A compressor (<NUM>) according to yet another aspect is the compressor as defined in any one of <NUM>) to <NUM>), including: a head cover (<NUM>) forming the discharge space (Sv) together with the valve plate (<NUM>). An outer peripheral edge portion of the valve plate is interposed between an outer peripheral edge portion of the compressor casing (<NUM>) and an outer peripheral edge portion of the head cover.

With such configuration, the outer peripheral edge portions of the three layers, namely, the head cover, the valve plate, and the compressor casing are fastened together with fasteners such as bolts, making it easier to mount the valve plate. Further, the outer peripheral edge portion of the valve plate is exposed to the outside, making it easier to externally connect the refrigerant supply pipe to the cooling medium path formed in the valve plate.

<NUM>) A compressor system (<NUM>) according to an aspect includes: the above-described compressor (<NUM> (10A, 10B, 10C)); a refrigerant circulation path (<NUM>) communicating with the suction space (Si) and the discharge space (Sv) of the compressor; a condenser (<NUM>) for condensing a discharge gas discharged from the discharge space; at least one branch path (<NUM>) branching off from the refrigerant circulation path downstream of the condenser and communicating with the cooling medium path (<NUM>); and a liquid pump (<NUM>) disposed on the branch path.

With such configuration, the refrigerant liquid flowing through the above-described branch path is pressurized by the liquid pump, and thus can be supplied to the cooling medium path. Consequently, since the partition wall portion disposed in the compressor is cooled, making it possible to suppress the decrease in volumetric efficiency of the compressor due to the heat input from the discharge space to the suction space. Thus, if the compressor system of the present disclosure is applied to the refrigeration system or the heat pump system, it is possible to suppress a decrease in COP (coefficient of performance). Further, since the partition wall portion disposed in the compressor is away from the compressor surface, the decrease in temperature on the compressor surface is suppressed. Therefore, it is possible to suppress occurrence of frost on the compressor surface.

<NUM>) A compressor system (<NUM>) according to another aspect is the compressor system as defined in <NUM>), including: a refrigerant discharge path (<NUM>, <NUM>) for returning a cooling medium discharged from the cooling medium path (<NUM>) of the compressor (<NUM> (10A, 10B)) to the refrigerant circulation path (<NUM>). The refrigerant discharge path is connected to the refrigerant circulation path between the compressor and the condenser (<NUM>).

With such configuration, the refrigerant liquid pressurized by the liquid pump and supplied to the cooling medium path can be returned to the refrigerant circulation path on the high-pressure side between the compressor and the condenser. Therefore, the refrigerant used to cool the partition wall portion can be used as the working refrigerant of the compressor, and thus the supply of the refrigerant for cooling to the cooling medium path does not lower the performance of the compressor.

<NUM>) A compressor system according to an aspect includes: the above-described compressor (<NUM> (10A, 10B, 10C)); a refrigerant circulation path (<NUM>) communicating with the suction space (Si) and the discharge space (Sv) of the compressor; a condenser (<NUM>) for condensing a discharge gas discharged from the discharge space; an expansion valve (<NUM>) for decompressing a condensate liquid of the discharge gas condensed in the condenser; at least one branch path (<NUM>) branching off from the refrigerant circulation path between the condenser and the expansion valve, and communicating with the cooling medium path (<NUM>); and a refrigerant discharge path (<NUM>, <NUM>) for returning a cooling medium discharged from the cooling medium path of the compressor to the refrigerant circulation path between the expansion valve and the compressor.

With such configuration, since the refrigerant circulation path between the expansion valve and the compressor has the lower pressure than the branch path, even if the branch path is not provided with the liquid pump, the refrigerant supplied to the cooling medium path can be returned to the refrigerant circulation path in the low-pressure area in question via the refrigerant discharge path.

<NUM>) A compressor system (<NUM>) according to an aspect includes: a refrigerant circulation path (<NUM>); a low-stage compressor (10a) and a high-stage compressor (10b) disposed in series in the refrigerant circulation path; and a condenser (<NUM>) for condensing a discharge gas discharged from the discharge space of the high-stage compressor. The low-stage compressor is constituted by the above-described compressor (<NUM> (10A to 10C)). The compressor system includes: a branch path (76a) branching off from the refrigerant circulation path downstream of the condenser (<NUM>) and communicating with the cooling medium path of the low-stage compressor; and a refrigerant discharge path (42a, 60a) for returning a cooling medium discharged from the cooling medium path (<NUM>) of the low-stage compressor to the refrigerant circulation path (intermediate path <NUM> (72a)) between the low-stage compressor and the high-stage compressor.

With such configuration, since the above-described intermediate path has a lower pressure than the branch path 76a, the refrigerant gas after cooling the partition wall portion in the cooling medium path of the low-stage compressor can be returned to the intermediate path via the refrigerant discharge path.

<NUM>) A compressor system (<NUM>) according to an aspect includes: a refrigerant circulation path (<NUM>); a low-stage compressor (10a) and a high-stage compressor (10b) disposed in series in the refrigerant circulation path; and a condenser (<NUM>) for condensing a discharge gas discharged from the discharge space (Sv) of the high-stage compressor. The high-stage compressor is constituted by the above-described compressor (<NUM> (10A to 10C)). The compressor system includes: a branch path (76b) branching off from the refrigerant circulation path downstream of the condenser and communicating with the cooling medium path (<NUM>) of the high-stage compressor; a liquid pump (<NUM>) disposed on the branch path; and a refrigerant discharge path (42b, 60b) for returning a cooling medium discharged from the cooling medium path of the high-stage compressor to the refrigerant circulation path.

With such configuration, since the refrigerant liquid supplied from the above-described branch path to the cooling medium path of the high-stage compressor is pressurized by the liquid pump, the refrigerant liquid can be supplied to the cooling medium path of the high-stage compressor, and the refrigerant after cooling the partition wall portion in the refrigerant discharge path can be returned to the refrigerant circulation path via the refrigerant discharge path.

<NUM>) A compressor system (<NUM>) according to an aspect includes: a refrigerant circulation path (<NUM>); a low-stage compressor (10a) and a high-stage compressor (10b) disposed in series in the refrigerant circulation path; and a condenser (<NUM>) for condensing a discharge gas discharged from the discharge space (Sv) of the high-stage compressor. The high-stage compressor is constituted by the above-described compressor (<NUM> (10B, 10C)). The compressor system includes: a branch path (76b) branching off from the refrigerant circulation path downstream of the condenser and communicating with the cooling medium path of the high-stage compressor; and a refrigerant discharge path (42b, 60b) for returning a cooling medium discharged from the cooling medium path (<NUM>) of the high-stage compressor to the refrigerant circulation path (intermediate path <NUM> (72a)) disposed between the low-stage compressor and the high-stage compressor.

Claim 1:
A compressor (<NUM>), comprising:
a cylinder (<NUM>);
a piston (<NUM>) configured to be reciprocable in the cylinder;
a suction space (Si) capable of communicating with a working chamber (Sc) formed by the cylinder and the piston;
a compressor casing (<NUM>) for housing the cylinder (<NUM>) and the piston (<NUM>),
a discharge space (Sv) capable of communicating with the working chamber;
a suction valve (<NUM>) for switching a state of communication between the suction space (Si) and the working chamber (Sc);
a discharge valve (<NUM>) for switching a state of communication between the discharge space and the working chamber;
a partition wall portion (<NUM>) disposed so as to surround the working chamber, and separating the suction space and the discharge space, a valve plate (<NUM>) holding the suction valve and the discharge valve, the valve plate serving as the partition wall portion (<NUM>); and
a head cover (<NUM>) provided above the partition wall portion (<NUM>),
wherein the compressor casing (<NUM>) is configured to include the suction space (Si), and
the head cover (<NUM>) is configured to form the discharge space (Sv) together with the valve plate (<NUM>),
the compressor being characterized in that
the compressor comprises a cooling medium path (<NUM>) formed in the valve plate as the partition wall portion which separates the suction space of the compressor casing and the discharge space formed by the head cover and the valve plate.