Patent Application
20070186878
The present disclosure relates to cooling systems and, more particularly, to cooling systems for vehicles such as work vehicles.
The cooling system of a vehicle may be used to manage the temperature of one or more onboard component(s). For example, in the case of work vehicles, the cooling system may be used to cool or warm the engine, a charge air cooler, and/or an oil cooler.
According to the present disclosure, a dual-circuit cooling system for a vehicle is comprises first and second fluid circuits. The first fluid circuit is used to manage the temperature of an engine of the vehicle. The second fluid circuit is fluidly coupled to the first fluid circuit for communication of coolant therebetween and comprises a radiator and a radiator bypass in parallel with the radiator for use in managing the temperature of a component of the vehicle other than the engine. An associated method is disclosed.
The above and other features will become apparent from the following description and the attached drawings.
The detailed description particularly refers to the accompanying figures in which:
Referring now to the
Exemplarily, a pump 22 is integrated into both circuits 14, 16 so as to be in common therewith to pump coolant therethrough. As such, the circuits 14, 16 share a common supply of coolant. An expansion tank (not shown) may be included to receive coolant overflow from radiators of the circuits 14, 16.
The first fluid circuit 14 thermostatically manages the temperature of the engine 18. Coolant is advanced by the pump 22 to a first heat exchanger 24 associated with the engine 18. The exchanger 24 is, for example, a coolant jacket of the engine 18 that circulates coolant about the engine 18 to transfer heat between the engine 18 and the coolant either to cool or warm the engine 18.
Downstream from the exchanger 24 is a first thermostat 26 (e.g., thermostatic valve) which selectively directs coolant between a first radiator 28 (“high temperature radiator”) and a first radiator bypass 30 parallel to the radiator 28 in response to temperature. When the coolant temperature is below a predetermined temperature, the thermostat 26 directs coolant through the first bypass 30 back to the pump 22 so that the coolant bypasses the first radiator 28, thereby promoting warm-up of the engine 18. At the predetermined temperature, the thermostat 26 starts to open to begin allowing flow of coolant to the first radiator 28 for transfer of heat away from the coolant to air flowing past the radiator 28, the flow of air resulting, for example, from operation of an onboard cooling fan and/or movement of the vehicle 12 along the ground. With increasing coolant temperature, the thermostat 26 opens more and more such that all, or at least a substantial amount, of the coolant flows to the radiator 28 for subsequent cooling of the engine 18. The pump 22 receives coolant flow from the bypass 30 and/or the radiator 28 to begin the cycle anew.
A portion of the coolant pressurized by the pump 22 is introduced into the second fluid circuit 16. Such coolant flows to a second thermostat 32 (e.g., thermostatic valve) of the circuit 16. An inlet port 34 of the thermostat 32 is fluidly coupled to the pump 22 to receive coolant therefrom. The thermostat 32 selectively directs coolant between a second radiator 36 (“low temperature radiator”) and a second radiator bypass 38 in parallel with the second radiator 36 in response to temperature. As such, the thermostat 32 has a first outlet 40 fluidly coupled to the radiator 36 to discharge coolant thereto and a second outlet 42 fluidly coupled to the radiator bypass 38 for discharge of coolant thereto. The thermostat 32 is thus positioned fluidly between the pump 22 and the radiator 36 and between the pump 22 and the bypass 38.
The thermostat 32 is configured so as to direct coolant to the bypass 38 when the coolant temperature is below a predetermined temperature (e.g., 60 C.°). In such a case, all or at least a substantial amount of the coolant flows through the bypass 38 to one or more heat exchangers 44, thereby bypassing the radiator 36. This is useful during cold-start conditions when the component(s) 20 in thermal communication with the exchanger(s) 44 are relatively cold. Use of the bypass 38 thus enables relatively quick warming of the component(s) 20 at times when such warming is needed, thereby enhancing the performance of the vehicle 12.
At the predetermined temperature, the thermostat 32 starts to open to begin allowing coolant to flow to the exchanger(s) via the radiator 36. Coolant flowing through the radiator 36 is cooled due to transfer of heat from the coolant to air flowing past the radiator 36. The radiator 36 may be stacked in front of or behind the radiator 28 to benefit from air flow resulting from operation of the onboard cooling fan and/or movement of the vehicle 12. With increasing temperature at the thermostat 32, the thermostat continues to open allowing more coolant to flow through the radiator 36 to the exchanger(s) 44. The thermostat 32 may be configured such that eventually most, if not all, of the coolant in the circuit 16 flows through the radiator 36.
Coolant discharged from the radiator 36 and the bypass 38 flows to the one or more exchangers 44. Exemplarily, the exchanger(s) 44 may include, but is(are) not limited to, one or more charge air coolers for cooling engine intake air charged by a turbocharger (“charge air”), one or more hydraulic oil coolers, and/or a transmission oil cooler. As such, the component(s) may include, but is(are) not limited to, charge air, hydraulic oil for hydraulic functions onboard the vehicle 12, and/or transmission oil for a transmission onboard the vehicle 12. After passing through the exchanger(s) 44, coolant flows back to the pump 22. Illustrative embodiments of the exchanger(s) 44 are shown in
In the circuit 16, coolant is always able to flow to the exchanger(s) 44 during operation of the vehicle 12 regardless of temperature, either through the bypass 38, the radiator 36, or both. This enables the circuit 16 to respond relatively quickly to instantaneous heat loads of the component(s) 20 at one or more of the exchanger(s) 44 (e.g., charge air cooler, hydraulic oil cooler, transmission oil cooler) to cool such heat loads relatively quickly, thereby enhancing the performance of the vehicle 12. This is in contrast to possible arrangements where there is not a bypass 38 such that the transient response of the system 10 to the heat loads is predominantly dependent on the temperature responsiveness of the thermostat 32 to allow passage of coolant through the radiator 36 to the exchanger(s) 44, resulting in a relatively slower reaction time to the head loads.
By fluidly connecting the first and second fluid circuits 14, 16 to one another via the single pump 22, coolant is able to flow between the circuits 14, 16. As a result, the radiator 28 of the circuit 14 is able to, in effect, add cooling capacity to the radiator 36 of the circuit 16, allowing for a smaller radiator 36 than in a situation where the circuits 14, 16 might be independent of one another. In addition, use of a single pump, as opposed to a pump for each circuit 14, 16, results in cost savings and promotes space economy.
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The cooling system 10 may be used with a number of vehicles including, but not limited to work vehicles. Examples of such work vehicles for which the cooling system 10 may be especially useful include, but are not limited to, backhoes, loaders, excavators, motor graders, crawlers, and forestry vehicles, to name just a few.
While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. It will be noted that alternative embodiments of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present invention as defined by the appended claims.
