Patent Application
20100018674
This invention relates to a cooling or heating system having a primary and secondary loop that includes a reservoir in a secondary loop that provides a potential reserve of cooling or heating capacity for improved performance. More particularly, this invention relates to a reservoir in the secondary loop with a moveable partition that increases or decreases the amount of liquid medium volume available to the flow path between the input port and the output port to quicken the attainment of a suitable predetermined occupant comfort level.
A prior U.S. Pat. No. 6,230,508 to Baker et al. discloses a secondary loop that contains a reservoir that provides a potential reserve of cooling capacity that maintains passenger comfort when the compressor is turned off for a short period of time. A potential drawback of the secondary loop is either a “hot soak” or long system shutdown condition.
A “hot soak” condition is one in which the liquid medium has “soaked up” heat from the environment and essentially reached equilibrium with it. With a long system shutdown, the reservoir of “cold” becomes a reservoir of “hot”, feeding the secondary system with hot liquid medium until the entire air conditioning system can be cooled down. With either condition, having hot liquid medium in the reservoir can actually lengthen the response time and delay passenger comfort.
Baker et al. overcomes the “hot soak” or long system shutdown condition with a complex reservoir design. A fixed interior wall in the reservoir separates liquid medium volume into a larger volume portion and a smaller volume portion. Liquid medium enters the reservoir from the secondary loop through a main line input port and an external bypass line input port. Liquid medium leaves the reservoir back into the secondary loop through a main line output port and an external bypass line output port. An external metering valve in the main line output port flow path is adjustable to be totally open, partially open, or totally closed. When the metering valve is totally closed, liquid medium ceases to flow through the main line output port flow path causing undesirable pressure buildup in the reservoir and the secondary loop.
Therefore, what is needed is an improved reservoir design that avoids the lag problem inherent in a “hot soak” or long system shutdown condition. Additionally, a reservoir with a single continuous flow path that is not turned off in normal system operation to prevent undesirable pressure buildup is desired.
A preferred embodiment of this invention is a cooling or heating system that has a primary loop through which pressurized liquid is circulated and a secondary loop through which a low pressure liquid medium is circulated to cool or heat an occupant space to a predetermined occupant level. The heat or cold in the secondary loop is transferred from the liquid medium across a heat exchanger into the occupant space. The secondary loop also contains a reservoir that contains a fixed amount of liquid medium at a fixed pressure. The reservoir has an exterior wall, an input port, and an output port. The input port and the output port are located in proximity to the exterior wall with the input port being located substantially opposed to the output port defining a flow path between the two. A moveable partition internal to the reservoir encloses the flow path between the moveable partition and the exterior wall of the reservoir. The moveable partition moves away from the exterior wall to increase the volume available to the flow path and the moveable partition moves toward the exterior wall to decrease the volume available to the flow path in response to the liquid medium temperature.
The present invention's features will become apparent to those skilled in the art from reading the accompanying drawings, in which:
Referring to
Primary loop 12 performs a conventional function of carrying pressurized refrigerant through the system pumped by a compressor 18. Pressurized liquid circulates in primary loop 12 from a refrigerant inlet/outlet 19 at chiller 16, proceeding to compressor 18, through a condenser 20 and an expansion valve 21, and ending back at refrigerant inlets/outlets 19 at chiller 16 to complete the loop.
Secondary loop 14 includes a liquid medium, typically an automotive grade coolant that circulates starting at a liquid inlet/outlet 22 at chiller 16, proceeds to a liquid heat exchanger 24, moves through a reservoir 26 and a low pressure pump 28, before returning to the liquid inlet/outlet 22 at chiller 16. When compressor 18 operates in primary loop, secondary loop 14 cools air blown into a vehicle occupant space 30 through heat exchanger 24 contained in a ventilation module 31.
A main advantage of secondary loop 14 is that it provides “reservoir capacity”, or thermal storage for improved air conditioning system performance in the liquid medium contained in reservoir 26 when compressor 18 in primary loop 12 does not operate. When compressor 18 does not operate, or is turned “off” for a short period of time, secondary loop 14 continues to operate and circulate reserve capacity liquid medium in reservoir 26 to temporarily maintain the suitable predetermined occupant comfort level in occupant space 30.
Reservoir 26, as shown in
Reservoir 26 has a general wedge shape, as shown in
Input port 34 is located higher with respect to output port 36 in reservoir 26 to allow air bubbles caught in secondary loop 14 a shorter distance to propagate out of the liquid medium into air volume located in a portion of reservoir 26 nearest cap 39.
Moveable partition 46 is connected to reservoir 26 at narrow end wall 44 and rotates about narrow end wall 44. Moveable partition 46 is controlled by the actuator motor 50 that moves moveable partition 46 away from exterior wall 32 to increase the volume available to flow path 38 and moveable partition 46 moves toward exterior wall 32 to decrease the volume available to flow path 38 as shown in
At system start-up when the system is hot, as shown in
At system start-up, with moveable partition 46 is in first position 56, only a minimal amount of “hot” liquid medium from reservoir 26 can flow in flow path 38 between the input port 34 and the output port 36 while the majority of “hot” liquid medium volume in reservoir 26 is sequestered by the moveable partition 26 from flow in flow path 38. Consequently, only a minimum amount of “hot” liquid medium is circulated in the secondary loop at system start-up until the system further cools down, thereby allowing quick recovery for a suitable predetermined occupant comfort level.
There is no seal between moveable partition 46 and reservoir 26. As liquid medium in flow path 38 initially cools down, coolant in proximity to flow path 38 begins to also cool down due to a residual mixture effect. As moveable partition is rotated away from exterior wall 32 in reservoir 26, more volume of liquid medium is available for flow in flow path 38 and is progressively cooled down.
As the system steady state condition is progressively achieved, the liquid medium in secondary loop 14 cools down, and moveable partition 46 moves away from exterior wall 32 to a second dotted-line position 56a to allow additional volume of “cooler” liquid medium in reservoir 26 to become available for flow in flow path 38.
When system steady-state condition is realized, moveable partition 46 moves to a third dotted-line position 56b that is farthest away from exterior wall 32 and opens the entire volume of liquid medium in reservoir 26 to flow path 38. With this invention it can be readily seen that the occupant space can reach a predetermined occupant comfort level more quickly with the liquid medium being progressively cooled down than if the entire volume of liquid medium in the reservoir had to be cooled down all at once. Therefore, as system steady-state conditions are achieved, the liquid medium in reservoir 26 attains a cold temperature and reservoir 26 becomes a “reserve capacity” of cold liquid medium to secondary loop 14. This “reserve capacity” of cold liquid medium is available to circulate in secondary loop 14 if there are temporary, shorter disruptions from compressor 18 in primary loop 12 to maintain the suitable predetermined occupant comfort level.
To further define and facilitate the flow of liquid medium through flow path 38 in reservoir 26 when moveable partition 46 is in first position 56, moveable partition 46 includes an integral channel 58, as seen in
To further quicken the cooling of liquid medium in the reservoir the moveable partition may also include one or more thru holes to facilitate movement of liquid within the reservoir. Baffles may also be designed on the moveable partition especially on the integral channel to provide limiting mixing of liquid medium or mixing at certain locations within the reservoir.
While three moveable partition positions (56, 56a, and 56b) are shown in
While the invention shows position control of the moveable partition with an actuator motor, other ways to control position may include a bimetal spring, or a gas thermostat. Other reservoir shapes and moveable partition shapes that can be used. For example, a cylindrical reservoir with a moveable partition that is a cylindrical shape may be employed.
The invention provides an improved, simplified reservoir design that provides high reliability for the secondary system to bridge temporary, shorter shutdowns of the primary refrigerant loop while avoiding the lag problem inherent in a “hot soak” or long system shutdown condition. The components for the reservoir are internal to the reservoir with the exception of the motor that is packaged within the overall footprint of the reservoir providing for an efficient, compact design. The flow of liquid medium enters one input port and exits one output port of the reservoir unobstructed which simplifies the flow path structure while providing a more efficient flow of liquid medium through the secondary loop. There is a continuous flow of liquid medium in the reservoir and secondary loop that is not turned off during system operation. Movement of the moveable partition in the reservoir does not create undesirable pressure fluctuation in the secondary loop. The moveable partition in the reservoir has an integral channel that provides focused movement and facilitates the speed of fluid flow in the flow path of the reservoir when the moveable partition is positioned next to the exterior wall when minimal liquid medium volume is available to the flow path. These intrinsic features of the invention function and work together to attain quick recovery for a suitable predetermined occupant comfort level.
While this invention has been described in terms of the preferred embodiment thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.
