Evaporative cooling technique to control the temperature of a vehicle driveline component

Abstract

A system for cooling vehicle driveline components, such as axles or wet disc brake assemblies utilizes evaporative cooling effects of liquid applied to an exterior surface on the housing. A liquid supply is coupled with an outlet and a controller determines when cooling is needed. Liquid is applied onto the housing from the outlet as cooling is needed. One example includes a plurality of fluid collectors on a portion of the housing exterior to increase the amount of liquid maintained on the housing to increase the evaporative cooling effect.

Description

BACKGROUND OF THE INVENTION

[0001] This invention generally relates to temperature control for vehicle driveline components. More particularly, this invention relates to utilizing an evaporative cooling effect to control the temperature of at least a portion of a driveline component on a vehicle.

[0002] A variety of vehicles are manufactured for a variety of purposes. Examples include passenger vehicles, heavy vehicles such as trucks, and off road vehicles. Each type of vehicle has particular component requirements to meet the needs of the typical situation in which the vehicle is placed during use. Accordingly, a variety of vehicle components have been developed, each having its own benefits and, in some cases, shortcomings or drawbacks.

[0003] In off-road type vehicles, for example, oil in the brake and axle assemblies tends to heat up during braking applications. In many cases, especially in the case of liquid cooled wet disc brakes, the generated heat exceeds that which can be dissipated by the axle assembly or brake assembly using normal passive methods.

[0004] The heat build up must be dissipated to maximize component life and performance. The fatigue performance of components such as gears decreases with incremental rises in temperature. By maintaining an adequate temperature for such components, the fatigue performance is enhanced.

[0005] Vehicle manufacturers and suppliers have been forced to design complex and often undesirably costly cooling systems in an attempt to regulate the temperature within the components resulting from braking applications. Alternative heat dissipation techniques are needed.

[0006] This invention provides a temperature regulation strategy that economically maintains at least a portion of a driveline component, such as an axle or brake assembly, within a desired operating range.

SUMMARY OF THE INVENTION

[0007] In general terms, this invention is a system for cooling a vehicle driveline component that utilizes an evaporative cooling effect from applying a liquid to a housing of the component.

[0008] A system designed according to this invention includes a housing that houses at least portions of the driveline component. A supply of liquid is supported on the vehicle in some strategic location. An outlet is coupled to the supply of liquid and supported relative to the housing such that liquid from the outlet is applied onto the housing. The liquid is allowed to evaporate so that it operates to cool the component. A controller determines when a temperature of the component is higher than a selected threshold and responsively causes liquid from the supply to be applied to the housing through the outlet.

[0009] In one example, at least one temperature sensor is associated with the driveline component and the temperature sensor communicates with the controller so that the controller knows when to cause liquid to be applied to the housing.

[0010] In one example, the housing includes a surface with at least one fluid collector facing generally toward the outlet from which the liquid is applied onto the housing. One example embodiment includes a plurality of such fluid collectors. The fluid collectors operate to at least temporarily maintain more of the liquid on the housing so that a greater evaporative cooling effect is achieved.

[0011] The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 schematically illustrates a system designed according to this invention.

[0013] FIG. 2 schematically illustrates an alternative embodiment of selected portions of the system schematically shown in FIG. 1.

[0014] FIG. 3A schematically illustrates a fluid collector feature designed according to one embodiment of this invention.

[0015] FIG. 3B is a cross-sectional illustration taken along the lines 3B-3B in FIG. 3A.

[0016] FIG. 4A schematically illustrates an alternative arrangement of fluid collectors designed according to an embodiment of this invention.

[0017] FIG. 4B is a cross sectional illustration taken along the lines 4B-4B in FIG. 4A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A system 20 for controlling the temperature of a driveline component 22 is shown schematically in FIG. 1. The illustrated driveline component 22 includes an axle assembly and a brake assembly, which may be a wet disc brake assembly, that is particularly useful for off-road vehicles. In one example, a single housing contains the operative parts of the assemblies. The internal, conventional components of the assemblies are not shown. An axle housing 24 and brake housings 26 and 28 are shown. The operation axle assembly and the brake assemblies control rotation of wheels 30 to propel the vehicle as known.

[0019] A supply 32 of a cooling liquid 33 preferably is supported on the vehicle in a convenient location. An outlet 34 is associated with the supply reservoir 32 so that the liquid 33 can be selectively applied to the component 22 as needed. In the illustrated example, the outlet 34 includes conduits 35, 36 and 38 that are positioned to extend over a majority of the surface of the axle housing 24 and the brake housings 26 and 28. The liquid 33 selectively is allowed to leave the reservoir 32, flow through the conduits 35, 36 and 38 and to exit openings 40 to drip onto the exterior surface of the component housings.

[0020] The size of the supply container 32 may vary depending on the vehicle, the expected need for cooling, the flow rate of the outlets and the liquid selected, for example. In one example the supply 32 holds approximately 20 gallons.

[0021] The example of FIG. 2 shows an alternative where the openings 40 are effectively replaced with misting nozzles 42 that apply a sprayed mist of the liquid 33 onto the component housing. In such an arrangement, the liquid preferably is pressurized or otherwise forced through the nozzles 42 to achieve the desired misting effect.

[0022] In one example, the cooling liquid is water. Other solutions are within the scope of this invention. Those skilled in the art who have the benefit of this description will be able to select an appropriate liquid for the needs of their particular situation.

[0023] The example of FIG. 1 includes a plurality of temperature sensors 50 associated with the driveline component 22. The illustrated example includes at least one sensor associated with each brake assembly 26 and 28. A plurality of sensors 50 are also associated with the axle assembly 24. The temperature sensors may be positioned to sense a temperature of the respective housings, for example. In another example, the temperature sensors are positioned within the housing to provide an indication of the temperature of a lubricant within the component assembly.

[0024] The temperature sensors 50 communicate with a controller 52. Hardware connections may be used or wireless communication between the sensors and the controller. The controller 52 preferably is programmed to recognize the temperature of one or more of the components in the driveline, which may need cooling, and to determine whether the current temperature is above a preselected threshold.

[0025] The controller 52 may be a dedicated microprocessor provided on the vehicle. A variety of commercially available microprocessors can be used and those skilled in the art who have the benefit of this description will be able to suitably program the controller to achieve the results needed for a particular vehicle under particular circumstances. Alternatively, the controller 52 may be a dedicated portion of an engine controller already present on the vehicle. A variety of such engine controllers are known.

[0026] Whenever the temperature exceeds the threshold, the controller 52 preferably controls a supply of the liquid 33 from the reservoir 32 to be applied onto the component housing. The illustration of FIG. 1 includes a control valve arrangement 54 that is operated by the controller 52 to regulate the amount of liquid applied to the housing. In another example, such as where the misting nozzles 42 are used, the control valve arrangement 54 includes a pump to pressurize the liquid 33 within the system.

[0027] The example illustrated in FIG. 1 relies upon gravity (i.e., the reservoir 32 is positioned higher than the outlet) so that the fluid flow occurs as desired. Given this description, those skilled in the art will be able to select an appropriate valve or flow control arrangement. One example includes a gravity feed dip tube that relies upon gravity to provide a constant supply of the liquid ready to be applied to the housing as needed. A variety of flow control and flow activation strategies are within the scope of this invention.

[0028] As the liquid 33 is applied onto the housing, at least a portion of it evaporates and provides an evaporative cooling effect to the housing. This assists in the process of dissipating heat from within the component assembly to reduce the temperature of oil or other lubricants within the housing.

[0029] The inventive arrangement provides an economical, robust and effective way of providing cooling to one or more driveline components. An enhancement to the arrangement shown in FIG. 1 is schematically illustrated in FIGS. 3A and 3B. A fluid collector 60 is supported on an exterior surface 62 of the component housing to retain, at least temporarily, additional fluid 33 on top of the housing to increase the amount of evaporative cooling. The example schematically illustrated in FIG. 3 includes a rim 64, which may be formed as part of the exterior housing or be secured to the housing in a conventional manner. The rim 64 and the exterior surface of the housing effectively form a pool or fluid collector 60 where the fluid 33 remains on the surface of the housing rather than dripping off before evaporation occurs.

[0030] Another arrangement is shown in FIGS. 4A and 4B where a plurality of fluid collectors 60 are provided on the exterior surface of the housing 24. In this example, a matrix or mesh of raised surfaces 66 are applied to the exterior surface of the housing to form the plurality of fluid collectors 60. In one example, a prefabricated mesh made from plastic, metal or a combination of such materials, is secured to the exterior surface of the housing in the region where the cooling liquid 33 is applied to the housing. The application method of the mesh will vary depending upon the material selected. The chosen material should be able to retain its shape and, thereby preserve the desired arrangement of the fluid collectors 60, when exposed to expected temperatures that the housing will reach.

[0031] In another example, the mesh of surfaces 66 comprises a coating applied to the component housing. A conventional masking technique may be used while a coating is deposited onto the surface to build up the surfaces 66 surrounding the fluid collectors 60. The depth of the fluid collectors depends upon the depth of the applied coating or the number of layers used, for example. Given this description, those skilled in the art will be able to select from among commercially available paints or other coating materials to apply a matrix or mesh of the coating sufficiently thick to achieve a plurality of liquid collectors 60 on at least a selected portion of the exterior surface of the component housing.

[0032] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.

Claims

1. A system for controlling a temperature of a vehicle driveline component, comprising:

a housing that houses at least portions of the driveline component;

a supply of liquid supported on the vehicle;

an outlet coupled to the supply of liquid that is supported relative to the housing such that liquid from the outlet is applied onto the housing such that the liquid evaporates and operates to cool the component; and

a controller that determines when a temperature of the component is higher than a selected threshold and causes liquid from the supply to be applied to the housing through the outlet.

2. The system of claim 1, including a temperature sensor that provides an indication of the temperature of the component to the controller.

3. The system of claim 2, wherein the temperature sensor is positioned to provide an indication of the temperature of a lubricant within the housing.

4. The system of claim 1, including a surface on the housing facing generally toward the outlet, the surface including at least one fluid collector that at least temporarily collects some of the fluid applied to the housing.

5. The system of claim 4, including a plurality of fluid collectors.

6. The system of claim 5, wherein the housing surface comprises a mesh that is secured to the housing.

7. The system of claim 6, wherein the mesh comprises at least one of plastic or metal.

8. The system of claim 4, wherein the surface comprises a coating applied to the housing in a pattern that includes at least one region where the coating is not applied or is thinner than other regions and wherein the at least one region forms the collector.

9. The system of claim 8, wherein the coating comprises paint.

10. The system of claim 1, wherein the outlet comprises an opening in a tube through which the liquid drips onto the housing.

11. The system of claim 1, wherein the outlet comprises a misting nozzle through which the liquid is sprayed onto the housing.

12. The system of claim 1, wherein the component comprises at least one of an axle assembly or a wet disc brake assembly or a combination of the axle assembly and the wet disc brake assembly.

13. A method of cooling a vehicle driveline component that has a housing, comprising the steps of:

determining when a temperature of the component is above a chosen threshold; and

applying a liquid to the housing and allowing the liquid to evaporate to thereby cool the component.

14. The method of claim 13, including dripping water onto the housing.

15. The method of claim 13, including spraying a mist of water onto the housing.

16. The method of claim 13, including providing a surface on the housing that includes a plurality of liquid collectors that at least temporarily collect the liquid applied the housing to thereby increase an amount of the liquid that evaporates off from the housing.