Compressor system including a flow and temperature control device

A compressor system including a lubricant inlet compresses a gas and discharges a mixed flow of compressed gas and lubricant. A valve housing includes a hot and a cooled lubricant inlet, and a lubricant outlet. A sleeve is disposed within the valve housing and is movable between a first and a second position. The sleeve defines a mixing chamber and includes a first aperture with the hot lubricant inlet and a second aperture with the cooled lubricant inlet. The hot and cooled lubricant mix in the mixing chamber are directed to the lubricant inlet of the compressor. A thermal element is positioned to sense a temperature and moves the sleeve in response. The movement of the sleeve varies the amount of hot lubricant admitted through the first aperture and varies the amount of cooled lubricant admitted through the second aperture to control a lubricant temperature.

BACKGROUND

The present invention relates to compressors. More particularly, the present invention relates to a mechanism for managing the flow and temperature of lubricant in a compressor system.

A compressor system including, for example a contact-cooled rotary screw airend, injects a lubricating coolant such as oil into the compression chamber to absorb the heat created by the compression of air. The temperature of the oil must be maintained within a range to maximize its life and to minimize the formation of condensation within the compressor system. The amount and temperature of the injected oil also has an effect on the overall performance of the airend.

SUMMARY

In one construction, the invention provides a compressor system including a compressor including a gas inlet and a lubricant inlet. The compressor is operable to compress a gas and discharge a mixed flow of compressed gas and lubricant. A valve housing includes a hot lubricant inlet, a cooled lubricant inlet, and a lubricant outlet connected to the lubricant inlet of the compressor. A sleeve is disposed within the valve housing and is movable between a first position and a second position. The sleeve at least partially defines a mixing chamber and includes a first aperture in fluid communication with the hot lubricant inlet to selectively admit a hot lubricant into the mixing chamber and a second aperture in fluid communication with the cooled lubricant inlet to selectively admit a cooled lubricant into the mixing chamber. The hot lubricant and cooled lubricant mix in the mixing chamber to define a bulk lubricant that is directed to the lubricant inlet of the compressor via the lubricant outlet. A thermal element is positioned to sense a temperature and is coupled to the sleeve to move the sleeve in response to the sensed temperature. The movement of the sleeve is operable to vary the amount of hot lubricant admitted through the first aperture and to vary the amount of cooled lubricant admitted through the second aperture to control a temperature of the bulk lubricant.

In another construction, the invention provides a compressor system including a compressor including a gas inlet and a lubricant inlet. The compressor is operable to compress a gas and discharge a mixed flow of compressed gas and lubricant. A valve housing includes a hot lubricant inlet, a cooled lubricant inlet, and a lubricant outlet connected to the lubricant inlet of the compressor. A sleeve is disposed within the valve housing and at least partially defines a mixing chamber. The sleeve includes a first aperture of a first size in fluid communication with the hot lubricant inlet to selectively admit a hot lubricant into the mixing chamber. The sleeve further includes a second aperture in fluid communication with the cooled lubricant inlet to selectively admit a cooled lubricant into the mixing chamber. The second aperture is of a second size larger than the first size. The hot lubricant and cooled lubricant mix in the mixing chamber to define a bulk lubricant that is directed to the lubricant outlet. An actuator is coupled to the sleeve and is operable to move the sleeve between a first position and a second position. In the first position, the first aperture is fully open and the second aperture is fully closed such that all of the lubricant flowing into the mixing chamber flows through the first aperture and amounts to a first quantity of the lubricant. In the second position, the first aperture is closed and the second aperture is partially open such that all of the lubricant flowing into the mixing chamber flows through the second aperture and amounts to a second quantity that is about equal to the first quantity. The sleeve is further movable between the second position and a third position in which the first aperture is closed and the second aperture is fully open such that all of the lubricant flowing into the mixing chamber flows through the second aperture and amounts to a third quantity that is greater than the first quantity.

In yet another construction, the invention provides a compressor system including a compressor including a gas inlet and a lubricant inlet. The compressor is operable to compress the gas and discharge a mixed flow of compressed gas and lubricant. A valve housing includes a hot lubricant inlet, a cooled lubricant inlet, and a lubricant outlet connected to the lubricant inlet of the compressor. A sleeve is disposed within the valve housing and includes a first aperture in fluid communication with the hot lubricant inlet and a second aperture in fluid communication with the cooled lubricant inlet. The first aperture has a size that provides for the passage of a desired quantity of fluid to the lubricant outlet and the second aperture is sized to provide for the passage of an excess quantity of fluid that is greater than the desired quantity of fluid to the lubricant outlet. A thermal element is positioned to sense a temperature and is coupled to the sleeve to move the sleeve in response to the sensed temperature. The sleeve is movable between a first position and a second position. The first aperture and the second aperture cooperate to direct the desired quantity of lubricant to the lubricant outlet. The sleeve is further movable between the second position and a third position where the second aperture alone directs a quantity of lubricant to the lubricant outlet, the quantity being between the desired quantity and the excess quantity.

DETAILED DESCRIPTION

FIG. 1illustrates a compressor system20including a compressor airend (referred to herein simply as the compressor24, an oil separator28, a filter32, an oil cooler36, and a control valve40. The compressor24compresses air and oil to produce an air/oil mixture having an elevated pressure compared to the air and oil supplied to the compressor24. Although referred to throughout as “air” and “oil”, the specific type of gas being compressed and the specific type of lubricating coolant injected for compression with the gas is not critical to the invention, and may vary based on the type of compressor, the intended usage, or other factors.

The air and oil compressed within the compressor24undergoes an increase in pressure and also temperature. The air/oil mixture is directed from the compressor24to the oil separator28along an air/oil or “compressor outlet” flow path44as shown inFIG. 1. The oil separator28separates the air/oil mixture into two separate flows, a flow of compressed air that exits the oil separator28along a first outlet flow path48, and a flow of oil that exits the oil separator28along a second outlet flow path52. The compressed air in the first outlet flow path48can be supplied to any point-of-use device or to additional processing components or assemblies (not shown) of the compressor system20, such as a cooler, dryer, additional compressor(s), etc. The flow of oil in the second outlet flow path52from the oil separator28is directed to the filter32, which filters the oil of contaminants before it is returned to the compressor24.

From the filter32, the oil can be directed along one of two separate flow paths to the control valve40. The first flow path56directs oil directly from the filter32to the control valve40without cooling the oil. The second flow path60between the filter32and the control valve40directs oil through the oil cooler36that is positioned along the second flow path60. A first portion60A of the second flow path60is an oil cooler inlet flow path, and a second portion60B of the second flow60is an oil cooler outlet flow path.

Both of the flow paths56,60from the filter32lead to the control valve40, which has a single outlet leading to an oil supply flow path64which supplies the oil back to the compressor24. By selective restriction of the flow through the valve40from each of the flow paths56,60to the valve outlet (i.e., the oil supply flow path64), the valve40controls how much of the oil flowing through the filter32is directed through the cooler36and how much is passed directly from the filter32to the valve40. The first outlet flow path56from the filter32is an inlet flow path to a first inlet70A of the valve40(FIG. 2). The second outlet flow path60from the filter32is an inlet flow path to a second inlet70B of the valve40(FIG. 2).

As illustrated byFIGS. 2-4, the control valve40includes a body74, a sleeve76movable within a chamber78formed in the body74, and a thermal element or actuator80positioned at an end of the sleeve76. The first inlet70A of the valve40is in communication with a first annular passage84A that surrounds the sleeve76. The second inlet70B of the valve40is in communication with a second annular passage84B that surrounds the sleeve76. The first and second annular passages84A,84B are spaced from each other along an axis88of the valve40defined by the chamber78and the sleeve76. The sleeve76includes a first aperture92A in selective communication with the first annular passage84A and a second aperture92B in selective communication with the second annular passage84B. The second aperture92B is larger than the first aperture92A. Both of the apertures92A,92B are in communication with a mixing chamber96defined by the inside of the sleeve76, which is substantially hollow and cylindrical in the illustrated construction. The mixing chamber96is in communication with the valve outlet (and thus, the oil supply flow path64) so that all of the oil supplied to the mixing chamber96(whether from the first inlet70A or the second inlet70B, or both) is directed to the oil supply flow path64. The oil transferred from the mixing chamber96to the oil supply flow path64through the valve outlet is referred to as the “bulk” flow of oil (or “combined” flow if oil that is received from both inlets70A,70B).

Although the first aperture92A is illustrated as the only aperture for admitting oil into the mixing chamber96from the first inlet70A and the second aperture92B is illustrated as the only aperture for admitting oil into the mixing chamber96from the second inlet70B, either one or both of the first and second apertures92A,92B can be one of a plurality of apertures spaced around the sleeve76to admit oil into the mixing chamber96from multiple angles about the respective annular passages84A,84B. Regardless of whether the first and second apertures92A,92B are the only two apertures or are each a part of a respective plurality of apertures, the functional characteristics described below are equally applicable.

Under most conditions of operation, the flow of oil to the compressor24should not exceed a predetermined desired flow rate for maximum performance of the compressor24. Whenever the compressor24is operating at a temperature below a first predetermined set point, the sleeve76is in a first position as shown inFIG. 2. In the first position, the first aperture92A is fully exposed to the first annular passage84A and the second aperture92B is fully blocked from communication with the second annular passage84B. Thus, none of the flow of oil from the filter32is supplied to the valve40through the oil cooler36. Rather, all of the flow of oil from the filter32to the valve40is provided through the first flow path56, which is a flow path between the filter32and the valve40along which the oil is not actively cooled. The flow path may be a direct flow path between the filter32and the valve40as shown inFIG. 1. The first aperture92A in the sleeve76is sized to provide a minimum required flow of oil when the sleeve76is in the first position. If the first aperture92A is one of a plurality of apertures in communication with the first annular passage84A, the plurality of apertures as a whole are sized to provide a minimum required flow of oil when the sleeve76is in the first position.

When the compressor24is operating at a temperature from the first predetermined set point up to a second predetermined set point, the sleeve76is gradually moved by the actuator80from the first position toward a second position (FIG. 3) as described in further detail below. In the second position, the second aperture92B is partially exposed to the second annular passage84B and the first aperture92A is fully blocked from communication with the first annular passage84A. Thus, none of the flow of oil from the filter32is supplied to the valve40directly through the first flow path56. Rather, all of the flow of oil from the filter32to the valve40is provided through the second flow path60, which directs the flow of oil through the oil cooler36before delivering it to the valve40. When the sleeve76is in the second position, the exposed portion of the second aperture92B in the sleeve76provides a flow of cooled oil about equal to the minimum required flow (i.e., about equal to the flow of oil provided through the first aperture92A when the sleeve76is in the first position). During the transition between the first position and the second position, portions of both apertures92A,92B are exposed to the respective annular passages84A,84B so that a mix of “hot” oil (i.e., un-cooled by the oil cooler36) and cooled oil is provided to the oil supply flow path64. The remaining portions of both apertures92A,92B are blocked. At all times during the transition between the first position and the second position of the sleeve76, the overall flow (i.e., “combined flow” or “bulk flow”) of oil remains the same (i.e., about equal to the minimum required flow provided by the first aperture92A in the first position) as the combined size of the portions of the apertures92A,92B that are exposed is about equal to the size of the first aperture92A.

When the compressor24operates at a temperature above the second set point, the first aperture92A remains closed and an increasingly greater portion of the second aperture92B is gradually exposed to the second annular passage84B, and thus the second inlet70B. Thus, only cooled oil is provided to the oil supply flow path64, similar to the sleeve76in the second position (FIG. 3). However, as the sleeve76moves from the second position (FIG. 3) toward a third position (FIG. 4), the overall flow of oil gradually increases, in excess of the minimum flow to provide additional cooling. The second aperture92B in the sleeve76is sized to provide a maximum flow of cooled oil when fully open (i.e., fully exposed to the second annular passage84B and the second inlet70B when the sleeve76is in the third position). If the second aperture92B is one of a plurality of apertures in communication with the second annular passage84B, the plurality of apertures as a whole are sized to provide a maximum flow of cooled oil when fully open.

The actuator80includes a sensor portion80A and a prime mover portion80B. The sensor portion80A is positioned in a chamber100of the valve body74that is remote from the chamber78that houses the sleeve76. The chamber100, and thus the sensor portion80A of the actuator80, is in fluid communication with the oil or the air/oil mixture.FIG. 1illustrates three possible paths A, B, C for fluidly coupling the chamber100with oil or the air/oil mixture. Each of the paths A, B, C represents a potential tubing or piping conduit for fluidly coupling the chamber100and the sensor portion80A with a fluid of the compressor system20. The first path A couples the chamber100to the oil supply flow path64at a position just upstream of the compressor24. Thus, the sensor portion80A of the actuator80senses and reacts to the temperature of the oil just prior to injection into the compressor24. The second path B couples the chamber100to the air/oil mixture just downstream of the compressor24. Thus, the sensor portion80A of the actuator80senses and reacts to the temperature of the air/oil mixture just after ejection from the compressor24. The third path C couples the chamber100to the oil just downstream of the oil separator28. Thus, the sensor portion80A of the actuator80senses and reacts to the temperature of the oil just after separation from the compressed air/oil mixture.

In some constructions where the sensor portion80A of the actuator80is fluidly coupled along path A ofFIG. 1, the valve40may be physically coupled to the compressor24or positioned directly adjacent the oil inlet of the compressor24where the oil supply flow path64injects oil into the compressor24so that the sensor portion80A may be positioned directly in or adjacent to the compressor's oil inlet. In some constructions where the sensor portion80A of the actuator80is fluidly coupled along path B ofFIG. 1, the valve40may be physically coupled to the compressor24or positioned directly adjacent the outlet of the compressor24where the compressed air/oil mixture is ejected from the compressor24to the outlet flow path44so that the sensor portion80A may be positioned directly in or adjacent to the compressor's outlet. In some constructions where the sensor portion80A of the actuator80is fluidly coupled along path C ofFIG. 1, the valve40may be physically coupled to or positioned directly adjacent the outlet of the oil separator28or the inlet of the filter32so that the sensor portion80A may be positioned directly in or adjacent to the separator outlet or the filter inlet. In other arrangements, the sensor portion80A is remotely located and fluid is directed along one of the paths A, B, or C to the sensor portion80A to allow the sensor portion80A to sense the fluid temperature. The operation of the valve40can be calibrated to control the temperature and the flow of oil based on the use of any one of the possible paths A, B, C.

In some constructions, the actuator80may be a diaphragm-type thermal actuator available from Caltherm Corporation of Columbus, Ind. The sensor portion80A of the actuator80can include an expansion material104contained within a cup108and configured to move the prime mover portion80B in a predetermined linear manner within the operating temperature range of the compressor24(i.e., the temperature range of the oil or air/oil mixture). In some constructions, the expansion material104is wax which changes phase from solid to liquid within the operating temperature range of the compressor24. The prime mover portion80B of the actuator80can include a piston112that is coupled to a diaphragm116with a plug120. The diaphragm116cooperates with the cup108to define a chamber that contains the expansion material104. A housing or piston guide124of the actuator80at least partially encloses the piston112and the plug120, and cooperates with the cup108to sandwich the diaphragm116in position. The exterior of the piston guide124includes male threads128for engaging the actuator80with a threaded aperture132of the valve body74.

Although the actuator80is illustrated to include a linearly traveling prime mover portion80B which actuates the sleeve76in a linear manner, a rotary type actuator can be substituted. The valve40can be reconfigured to selectively establish and terminate fluid communication between the inlets70A,70B and the apertures92A,92B upon rotative movement of the sleeve76within the chamber78or a transmission device can be provided to convert rotative movement to linear movement.

In some constructions, the actuator80may be an electro-mechanical actuator. In such constructions, the sensor portion80A of the actuator80can be an electrical sensor configured to output an electrical signal. The prime mover portion80B can be an electrical motor that is configured to move the sleeve76back and forth in a calibrated manner between the positions described above, based on the fluid temperature sensed by the sensor portion80A. The sensor portion80A and the prime mover portion80B can be located remotely from each other or adjacent each other.

In operation, the valve40operates to control the quantity and temperature of the oil delivered to the compressor24to assure that the minimum and most efficient quantity of oil is delivered to the compressor24unless the oil temperature demands additional flow. During compressor start-up, the compressor24and the oil are both cold. The oil does not perform optimally at this lower temperature and it is desirable to heat the oil to a desired temperature range as quickly as possible. The valve40senses this low oil temperature and maintains the sleeve in the position illustrated inFIG. 2. When in this position, none of the oil passes through the oil cooler36. Rather, the oil continues to circulate through the compressor24, thereby heating the oil. As the oil temperature enters the optimal temperature range, the sleeve76begins moving to the right toward the position illustrated inFIG. 3. Before reaching the position ofFIG. 3, some of the oil entering the mixing chamber96is cooled enough to remove an amount of heat about equal to the heat added by the compressor24during operation, thereby maintaining the oil within the desired range. As the load increases on the compressor24, the sleeve76eventually reaches the point illustrated inFIG. 3. At this point, all of the oil must be cooled to maintain the oil within the desired temperature range and of the desired flow rate. As load increases further, the oil temperature increases above the desired range. The actuator80senses this temperature and moves the sleeve76toward the position illustrated inFIG. 4. In this position, the valve40admits additional cooled oil to further cool the compressor24. Thus, the flow rate of oil to the compressor24only increases above the minimum predetermined amount when the oil temperature dictates that additional flow is required.

Thus, the invention provides, among other things, a compressor system20including a control valve40operable to mechanically control the temperature and the flow of oil to a compressor24. A sleeve76of the valve40is provided with multiple apertures to provide cooled, non-cooled, or mixed oil in variable predetermined flow amounts to the compressor24based on a sensed condition of the compressor24. Various features and advantages of the invention are set forth in the following claims.