Patent Description:
Typically, a multi-stage compressor is used in a vapor compression system including an economizer. A multi-stage compressor includes a first compressor stage and a separate second compressor stage arranged in fluid communication with an outlet of the first compressor stage. In operation, refrigerant compressed within the first compressor stage is discharged from an outlet of the first compressor stage and is delivered to an inlet of the second compressor stage. When used with an economizer, the refrigerant gas from the economizer is typically injected into the conduit connecting the two compressor stages. Accordingly, the refrigerant output from the first compressor stage and the refrigerant from the economizer are compressed together within the second compressor stage. Each compressor stage adds size, complexity, and cost to the compressor.

<CIT> discloses a dual-piston linear compressor including a first piston disposed in a first cylinder and a second piston opposed to the first piston and disposed in a second cylinder.

<CIT> discloses a compressor comprising a first compression chamber in a cylinder distal portion beyond the end of a piston and a second compression chamber in the cylinder proximal portion.

According to a first aspect of the invention there is provided a compressor. The compressor includes a housing having a suction inlet, at least one economizer inlet, and an outlet. A first cylinder arranged within the housing includes a first suction valve arranged in fluid communication with the suction inlet and a first discharge valve fluidly connected to the outlet. At least one second cylinder is arranged within the housing. The at least one second cylinder has a second suction valve in fluid communication with the at least one economizer inlet and a second discharge valve fluidly connected to the outlet. A first piston is arranged within the first cylinder and a second piston is arranged within the at least one second cylinder. The first cylinder has a first configuration and the at least one second cylinder has a second configuration, the first configuration and the second configuration being different. The first cylinder is configured to receive a first flow having a first pressure provided to the suction inlet and the at least one second cylinder is configured to receive a second flow having a second pressure provided to the at least one economizer inlet, the first pressure and the second pressure being different. Only the first flow provided to the suction inlet is compressed within the first cylinder and only the second flow provided to the at least one economizer inlet is compressed within the at least one second cylinder. The at least one second cylinder is distinct from the first cylinder.

Optionally, the fluid provided at the first discharge valve is configured to bypass the at least one second cylinder.

Optionally, the at least one second cylinder is smaller than the first cylinder.

Optionally, an amount of compression that occurs within the at least one second cylinder is reduced relative to an amount of compression that occurs within the first cylinder.

Optionally, a compression ratio of the first cylinder to the at least one second cylinder is between <NUM>:<NUM> and <NUM>:<NUM>.

Optionally, the at least one second cylinder includes a plurality of second cylinders and the at least one economizer inlet includes a plurality of economizer inlets, each of the plurality of second cylinders is arranged in fluid communication with a different one of the plurality of economizer inlets.

Optionally, at least one of the plurality of second cylinders has a different configuration than another of the plurality of second cylinders.

Optionally, the compressor includes a plurality of cylinders arranged within the housing. The plurality of cylinders includes the first cylinder configured to receive a first flow of refrigerant from the suction inlet and the second cylinder configured to receive a second flow of refrigerant from the economizer inlet. The second flow of refrigerant is compressed within the plurality of cylinders independently from the first flow of refrigerant.

Optionally, the second cylinder is smaller than the first cylinder.

Optionally, an amount of compression that occurs within the second cylinder is reduced relative to an amount of compression that occurs within the first cylinder.

According to yet another aspect of the invention there is provided a method of operating a compressor. The method includes providing a first flow of refrigerant to a suction inlet of the compressor, compressing the first flow of refrigerant within a first cylinder of the compressor, providing a second flow of refrigerant to an economizer inlet of the compressor, compressing the second flow of refrigerant within a second cylinder of the compressor, and delivering the first flow of refrigerant output from the first cylinder and the second flow of refrigerant output from the second cylinder to an outlet of the compressor. The first cylinder has a first configuration and the second cylinder has a second configuration, the first configuration and the second configuration being different, and only the first flow of refrigerant is compressed within the first cylinder, and only the second flow of refrigerant is compressed within the second cylinder. The first flow of refrigerant has a first pressure and the second flow of refrigerant has a second pressure, the first pressure and the second pressure being different. The second cylinder is distinct from the first cylinder.

Optionally, the first flow of refrigerant output from the first cylinder and the second flow of refrigerant output from the second cylinder are delivered to the outlet independently.

Optionally, the method comprises mixing the first flow of refrigerant output from the first cylinder and the second flow of refrigerant output from the second cylinder upstream from the outlet.

Optionally, the method comprises providing a third flow of refrigerant to a second economizer inlet of the compressor and compressing the third flow of refrigerant within another second cylinder of the compressor.

Certain embodiments of the invention will now be described in greater detail, by way of example only, and with reference to the accompanying drawings, in which:.

With reference now to <FIG>, an example of a compressor <NUM>, more specifically a reciprocating compressor, is illustrated. As shown, the compressor <NUM> has a housing <NUM> including a suction port or inlet <NUM> and a discharge port or outlet <NUM>. The housing <NUM> includes a cylinder block <NUM> having one or more bores <NUM> formed therein, each of which defines a "cylinder" of the compressor <NUM>. In an embodiment, a cylinder head <NUM> overlies a portion of the cylinder block <NUM>. As best shown in <FIG>, the cylinder head <NUM> includes one or more bores <NUM> corresponding to and aligned with the one or more bores <NUM> formed in the cylinder block <NUM>.

Each cylinder <NUM> is configured to accommodate a piston <NUM> mounted for reciprocal movement at least partially within a cylinder <NUM>. Examples of multicylinder configurations include, but are not limited to, in-line, V, and horizontally opposed. In the illustrated, non-limiting embodiment, the compressor <NUM> includes three cylinders <NUM>. However, it should be understood that a compressor <NUM> having a single cylinder, two cylinders, or more than three cylinders are also contemplated herein.

The one or more pistons <NUM> are coupled to a crankshaft <NUM> mounted within the housing <NUM>. A motor <NUM> operably coupled to the crankshaft <NUM> is configured to rotate the crankshaft <NUM> about an axis of rotation X. Rotation of the crankshaft <NUM> causes each piston <NUM> to reciprocate within a respective cylinder <NUM> within the interior of the cylinder block <NUM>.

With reference to <FIG>, a bore <NUM> formed in the cylinder head <NUM> may be divided into a plurality of fluidly distinct regions. The regions include a suction region <NUM> and a discharge region <NUM>. A plurality of valves are disposed at the interface between the bore <NUM> of the cylinder head <NUM> and a corresponding, aligned bore <NUM> within the cylinder block <NUM>. As shown, a suction valve <NUM> may be associated with the suction region <NUM> and a discharge valve <NUM> may be associated with the discharge region <NUM>. In an embodiment, the suction valve <NUM> and the discharge valve <NUM> are check valves or no-back valves. However, it should be understood that any suitable type of valve may be used. Accordingly, in an embodiment, one or both of the suction and discharge valves <NUM>, <NUM> may be actuated in response to a command from a controller C rather than automatically in response to a pressure or flow rate of the refrigerant acting thereon for example.

As a piston <NUM> moves downwardly within a respective cylinder <NUM>, a low pressure fluid, such as refrigerant gas for example, is drawn into the cylinder <NUM>. After reaching a bottom of the cylinder <NUM>, or the bottom of the cycle of movement of the piston <NUM>, the piston <NUM> begins to move upwardly within the cylinder <NUM>. As the piston <NUM> moves upwardly, the low pressure refrigerant gas within the cylinder <NUM> is compressed causing the pressure to build within the cylinder <NUM>. This increase in pressure in combination with the movement of the piston <NUM> causes the high pressure refrigerant gas to flow from the cylinder <NUM>.

An existing compressor configured for use with a vapor compression system including an economizer or economizing heat exchanger typically includes a first compressor stage having at least one first piston and a second compressor stage having at least one second piston. The flow from the economizer is provided via an economizer inlet to an intermediate region of the compressor arranged between the outlet of the first compressor stage and the inlet of the second compressor stage. As a result, the flow provided from the economizer bypasses the first compression stage and is therefore only compressed within the second compressor stage with the refrigerant flow output from the first compressor stage.

With reference now to <FIG>, a portion of a reciprocating compressor for use in a vapor compression system having one or more economizers is illustrated in more detail. In the illustrated, non-limiting embodiment, the compressor <NUM> includes at least one first cylinder 30a having a first configuration and at least one second cylinder 30b having a second configuration. Similar to the cylinders previously described with respect to <FIG>, a first piston 36a is movable within the first cylinder 30a and a second piston 36b is movable within the second cylinder 30b, respectively. In addition, a first suction valve 50a and a first discharge valve 52a are arranged between the bore 34a formed in the cylinder head <NUM> and the first cylinder 30a, and a second suction valve 50b and second discharge valve 52b are arranged between the bore 34b formed in the cylinder head <NUM> and the second cylinder 30b.

The at least one first cylinder 30a may be configured to receive a flow of low pressure gaseous refrigerant, such as provided to the compressor <NUM> from an evaporator located upstream of the compressor <NUM> within the vapor compression system. The one or more second cylinders 30b may be configured to receive a flow of a medium pressure gaseous refrigerant, such as provided to the compressor <NUM> from an economizer heat exchanger, also referred to herein as an economizer, of the vapor compression system. Although only a single first cylinder 30a and second cylinder 30b is shown in the FIG. , it should be understood that embodiments including any number of first and second cylinders 30a, 30b are contemplated herein. Further, the compressor <NUM> need not have an identical number of first cylinders 30a and second cylinders 30b.

In embodiments including a plurality of first cylinders 30a, each of the plurality of first cylinders 30a may have a similar or identical configuration. In embodiments where the compressor <NUM> includes a plurality of second cylinders 30b, also referred to herein as economizer cylinders, each of the plurality of second cylinders 30b may be configured to receive a flow from the same economizer within the vapor compression system. In such embodiments, each of the plurality of second cylinders 30b may have a similar configuration.

Alternatively, the plurality of second cylinders 30b may be configured to receive a flow from multiple economizers within the vapor compression system. For example, one second cylinder 30b may be associated with each economizer of the vapor compression system. If the vapor compression system has three separate economizers, each connected to a separate economizer inlet of the compressor <NUM>, the compressor <NUM> will include at least three second cylinders 30b, one associated with each economizer, respectively. In such embodiments, each of the plurality of second cylinders 30b may be designed based on the respective pressure of the refrigerant provided thereto. Accordingly, the plurality of second cylinders 30b may have similar, or alternatively, may have different configurations.

The configuration of the one or more first cylinders 30a is different from the configuration of the one or more second cylinders 30b. In the illustrated, non-limiting embodiment, the one or more second cylinders 30b are smaller than the one or more first cylinders 30a. As a result, less or a smaller amount of compression occurs within the second cylinders 30b than in the first cylinders 30a. In an embodiment, the amount of compression that occurs within the first cylinders 30a may be double or more than double, such as up to five times the amount of compression that occurs within the second cylinders 30b. For example, in an embodiment, the compression ratio of the compression that occurs within the first cylinder 30a relative to the compression that occurs within one of the second cylinders 30b may be anywhere between <NUM>:<NUM> and <NUM>:<NUM>. Further, in embodiments where the compressor <NUM> includes a plurality of second cylinders 30b, it should be understood that the ratio of compression of a first cylinder relative to each of the plurality of second cylinders 30b may vary.

In embodiments where the compressor <NUM> has a plurality of inlets arranged in fluid communication with a distinct component of a vapor compression system, each flow of refrigerant provided to one of the plurality of inlets is compressed independently of the other refrigerant flows provided to the other inlets of the compressor <NUM>. For example, in operation, a first flow of refrigerant having a first pressure provided to the main inlet or suction inlet <NUM> of the compressor <NUM> is delivered to the one or more first cylinders 30a through the first suction valve 50a. After compression within the at least one first cylinder 30a, the first flow of refrigerant is provided via the first discharge valve 52a to the outlet <NUM> of the compressor <NUM> for delivery to a downstream component within the vapor compression system. At the same time, a second flow of refrigerant provided from an economizer and having a second pressure is delivered to a second cylinder 30b via another inlet <NUM> of the compressor <NUM>, through second suction valve 50b. Within the second cylinder 30b, the second flow of refrigerant is compressed and then output via the second discharge valve 52b. The second flow of refrigerant output from the second cylinder 30b may be delivered to the same outlet <NUM>, or alternatively, to a different outlet as the first flow of refrigerant output from the at least one first cylinder 30a.

In embodiments where the two distinct flows are provided to the same outlet <NUM>, the compressed first flow of refrigerant output from the first cylinder 30a may be provided to the outlet <NUM> independently from the compressed second flow of refrigerant output from the second cylinder 30b. However, in other embodiments, the compressed flows may be mixed together upstream from the outlet <NUM>. In such embodiments, the resulting pressure of the flows output from both the at least one first cylinder 30a and the at least one second cylinder 30b may be substantially identical.

As described herein, only the flow of refrigerant provided to the suction inlet <NUM> is compressed within the one or more first cylinders 30a and only the flow of refrigerant provided from an economizer to an economizer inlet <NUM> is compressed within the one or more second cylinders 20b. Therefore, the compressed refrigerant output from any of the cylinders 30a, 30b need not be delivered to another compression stage or cylinder within the compressor <NUM>. In embodiments where the vapor compression cycle includes a second economizer, a third flow of refrigerant output from the second economizer and having a third pressure may be delivered to the compressor <NUM> via a second economizer inlet (not shown). This third flow of refrigerant may be compressed within another second cylinder of the plurality of second cylinders. However, it should be noted that the another second cylinder is a different second cylinder than the second cylinder used to compressed the flow from the economizer.

By providing a compressor <NUM> having a distinct cylinder or stage of cylinders associated with each flow of refrigerant provided to an inlet of the compressor <NUM>, each flow can be compressed within the compressor <NUM>. By using each stage of cylinders to compressor one of the flows, the need for sequential compressing of the refrigerant via multiple stages is eliminated. As a result, the foot print, complexity, and associated cost of the compressor <NUM> can be reduced.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting to the present invention.

Claim 1:
A compressor (<NUM>) comprising:
a housing (<NUM>) having a suction inlet (<NUM>), at least one economizer inlet (<NUM>), and an outlet (<NUM>);
a first cylinder (30a) arranged within the housing, the first cylinder (30a) having a first suction valve (50a) arranged in fluid communication with the suction inlet (<NUM>) and a first discharge valve (52a) fluidly connected to the outlet (<NUM>);
at least one second cylinder (30b) arranged within the housing, the at least one second cylinder (30b) having a second suction valve (50b) in fluid communication with the at least one economizer inlet (<NUM>) and a second discharge valve (52b) fluidly connected to the outlet (<NUM>); and
a first piston (36a) arranged within the first cylinder (30a) and a second piston (36b) arranged within the at least one second cylinder (30b),
wherein the first cylinder (30a) has a first configuration and the at least one second cylinder (30b) has a second configuration, the first configuration and the second configuration being different;
wherein the first cylinder (30a) is configured to receive a first flow having a first pressure provided to the suction inlet (<NUM>) and the at least one second cylinder (30b) is configured to receive a second flow having a second pressure provided to the at least one economizer inlet (<NUM>), the first pressure and the second pressure being different;
wherein only the first flow provided to the suction inlet (<NUM>) is compressed within the first cylinder (30a) and only the second flow provided to the at least one economizer inlet (<NUM>) is compressed within the at least one second cylinder (30b); and
wherein the at least one second cylinder (30b) is distinct from the first cylinder (30a).