Machine element or mechanism – Elements – Gear casings
Reexamination Certificate
1999-03-03
2001-02-20
Luong, Vinh T. (Department: 3682)
Machine element or mechanism
Elements
Gear casings
C074S60600R, C418S047000, C418S206100, C384S467000, C417S053000
Reexamination Certificate
active
06189411
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cooling of a rear wheel assembly, and more particularly to a rear end pump for cooling oil that is provided to a rear wheel gear assembly.
BACKGROUND OF THE INVENTION
Automobile racing has provided many years of entertainment for racing fans of all ages. With the advent of nationally recognized racing events, such as NASCAR WINSTON CUP automobile racing, BUSCH Grand National automobile racing and CRAFTSMAN Truck Racing, the financial incentive and exposure resulting from winning such events places a great deal of pressure on racing teams to out-perform one another. To remain competitive, racing teams are continuously developing and building automobiles, trucks and other racing vehicles that are capable of exceeding current speeds while remaining within vehicle component tolerances and standards. For example, depending on a particular type of racing circuit, various standards have been developed by an associated governing body in order to ensure the safety of the race car drivers and provide a relatively fair ground for competition. Consequently, most racing vehicle design and development has focused on improving the work efficiency of engine components, decreasing the overall weight of the racing vehicle, simplifying the serviceability of different vehicle components and improving the operating efficiency of the racing vehicle in general. Racing vehicles require constant revision of vehicle operating systems and vehicle components in order to improve vehicle performance, and each vehicle component contributes to at least one of the aforementioned factors.
One of the primary attractions of automobile racing is the high speed at which the racing vehicles operate. The drive train components of racing vehicles operate at high revolutions per minute (“RPM”) and generate tremendous amounts of heat from the friction and torque of one gear acting on another gear. Consequently, one consideration that affects the design and development of racing vehicle components is that such components must be substantially heat tolerant or have a cooling mechanism to counter the heat generated by the high RPM's. For example, in WINSTON Cup racing and most any other racing circuit, the racing vehicles are driven by rear wheel assemblies that operate at high RPM's. In particular, the differential gear assembly in a WINSTON Cup racing vehicle operates at high RPM's that are typically between about 9,000 to 10,000 RPM and at about 740 to 760 horsepower (HP). Consequently, the rear wheel assembly must be cooled.
One technique of cooling a rear wheel assembly is to use a rear end lubricant/coolant pump
12
(see FIG.
1
). The rear wheel assembly, shown generally at
14
, includes a rear gear assembly, not shown, contained in a rear gear assembly housing
18
, left and right axles, shown generally at
20
, a differential gear assembly (not shown), and other conventional related sub-components, such as bearings and seals. Lubricant/coolant is held in a reservoir (not shown) located at the bottom of the rear gear assembly housing
18
. During operation of the differential gear assembly, the gear assembly collects the lubricant/coolant from the reservoir and splashes the lubricant/coolant about the differential gear assembly. However, as the lubricant/coolant contacts the differential gear assembly, the heat from the differential gear assembly is transferred to the lubricant/coolant.
To cool the lubricant/coolant, the lubricant/coolant is circulated by the rear end lubricant/coolant pump
12
to an external cooler (not shown). The rear end lubricant/coolant pump
12
is externally mounted to the rear gear assembly housing
18
, connected to the reservoir by tubing
16
and coupled to a drive shaft
22
. In particular, the rear end lubricant/coolant pump
12
requires a pulley based system, shown generally at
26
, that is coupled to the drive shaft
22
to actuate the pump
12
. The rear end pump
12
is attached to a mounting plate
24
that is secured to the rear gear assembly housing
18
. A belt drive, shown generally at
25
, and corresponding pulleys
28
are attached to the mounting plate
24
adjacent to the pump
12
and coupled to the pump
12
. As the lubricant/coolant passes through the external cooler, the heat from the lubricant/coolant is exchanged to ambient air, and the resulting cooled lubricant/coolant is returned to the reservoir. The rear end lubricant/coolant pump
12
thus becomes a vital portion of the racing vehicle's rear wheel assembly for cooling the rear wheel assembly. An example of a rear end lubricant/coolant pump that is conventionally used in the NASCAR racing series is the SCP-102 and the SCP-101 recirculation pumps manufactured by Speedway Engineering.
Unfortunately, conventional rear end lubricant/coolant pumps are cumbersome to manipulate and include multiple external components that may become faulty during races. For example, conventional rear end lubricant/coolant pumps have a weight in excess of 6.5 pounds and are coupled to the drive shaft by a standard belt drive, as previously mentioned. The mounting plate, the belt drive and associated pulleys are additional elements that require maintenance and repair. Additionally, conventional drive shafts used in racing vehicles require a machined grooved pulley for receiving the belt of the belt drive.
Another problem with conventional rear end lubricant/coolant pumps is that the pump and any connected components must be removed and reinstalled in order to change any portion of the rear differential assembly, or rear axle assembly. Determining an appropriate gear ratio is vital to a racing vehicle's performance, and the removal and reinstallation of the conventional rear end lubricant/coolant pump substantially interferes with such determination. For example, the NASCAR racing series alots racing teams a predetermined and typically brief amount of time for practice track runs. This alotted time is particularly useful for fine tuning a racing vehicle and testing different gear ratios of the rear axle assembly. Unfortunately, when exchanging and testing the rear axle gear ratios during the alotted time, removal and installation of the rear end lubricant/coolant pump is an awkward task that consumes a great amount of the alotted time. Instead of expending valuable time removing and installing conventional rear end pumps, it is preferable to spend such time running practice laps with the purpose of testing additional gear ratios.
What is therefore needed is a pump for circulating lubricant/coolant to the rear axle assembly of a racing vehicle that maximizes the performance of the racing vehicle. In particular, what is needed is a pump for circulating lubricant/coolant to the rear axle assembly of a racing vehicle that is light weight and does not require removal during race activities and gear ratio exchanges. What is further needed is a pump for circulating lubricant/coolant to the rear axle assembly of a racing vehicle that increases the fluid thermal efficiency of the pump at high operating speeds.
SUMMARY OF THE INVENTION
The present invention is a pump for circulating lubricant/coolant to a differential or axle assembly of a vehicle that maximizes the performance of the vehicle. In particular, the present invention provides a pump for circulating lubricant/coolant to a rear axle assembly of a racing vehicle that maximizes the performance of the racing vehicle. The present invention provides a pump for circulating lubricant/coolant to the rear axle assembly of a racing vehicle that is light weight and does not require removal during race activities and gear ratio exchanges. More particularly, the present invention provides a pump for circulating lubricant/coolant to the rear axle assembly of a racing vehicle that is contained in the interior of the rear axle assembly housing and allows gear ratio exchange of the rear axle assembly without removing the pump. The present invention further provides a pump for circulating lubricant/coolant to the re
American Equipment Company
Dougherty & Clements LLP
Luong Vinh T.
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