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External hydraulic pump for motor vehicle transmission

External hydraulic pump for motor vehicle transmission description/claims

The provisional patent application entitled “EXTERNAL HYDRAULIC PUMP FOR MOTOR VEHICLE TRANSMISSION” which was filed on May 8, 2007, and granted Ser. No. 60/924,293, is hereby incorporated by reference in the present application.

This invention relates to a motor vehicle with a transmission and torque converter, and to an external electric pump for supplying of high pressure hydraulic fluid to the torque converter for proper operation, and low pressure hydraulic fluid to the transmission for lubrication. This pump may be used with both a standard transmission with clutch and torque converter as well as an automatic transmission with torque converter and no clutch.

With ever-increasing oil prices, improving the efficiency of the engine and transmission is a high priority for all motor vehicle manufacturers. Most engines now utilize fuel injection for improved efficiency over previously used carburetors, and the latest induction and exhaust systems have increased fuel mileage significantly.

The use of torque converters in motor vehicle transmissions is well known. The torque converter acts as a torque multiplier and speed differential mechanism between the engine and the transmission. The fluid coupling of the torque converter dampens the application of power from the engine to the transmission, and allows smoother operation of the vehicle. Torque converters are commonly used in automatic transmissions, but they may also be used with manual transmissions, and particularly with a modern dual clutch manual-type transmission.

Originally, mechanical pumps were used to provide pressurized hydraulic fluid to torque converters due to their inherent reliability advantages over such alternatives as electric pumps. Since the mechanical pump required a direct mechanical connection to a power source such as a turning shaft or the like, these pumps were located within the transmission or torque converter housing to allow this connection to be made without external shafts and seals being required.

Disadvantages of mechanical pumps include the fact that they will not function unless the engine is running, and as engine-driven accessories, they rob power from the engine during use. Additionally, the internal pump can be damaged if the pump ingests metal particles resulting from normal wear inside the transmission, or particles resulting from a small part partially disintegrating within the transmission, as frequently happens in high mileage transmissions.

The pump currently located inside the transmission requires that the transmission be completely removed from the vehicle for any pump service or repair. This repair is labor-intensive, and therefore expensive for the vehicle owner.

Over the years electric pumps have improved in reliability to equal that of their mechanical counterparts, erasing that disadvantage versus a mechanical pump. Since no mechanical connection is required for driving the electric pump, there is also no need for the pump to be located within the transmission housing. Being electrically driven, the inventive pump does not require that the vehicle engine be running to maintain fluid pressure and operational readiness, since electrical power for the pump is available from the vehicle storage battery with the engine running or not. With the increasing popularity of hybrid cars and engine-off-at-stops for fuel conservation, an electric pump offers the ability to operate on demand, regardless of vehicle engine operating conditions. Thus, the transmission and torque converter can be pressurized and fully operable even when the engine is not running.

This invention provides an electrically driven pump for providing high pressure hydraulic fluid to a motor vehicle torque converter and low pressure hydraulic fluid for lubrication of the transmission. Since the pump is not mechanically driven, it is not necessary that it be housed within the transmission or torque converter housing. It is advantageous that the pump be located outside the transmission housing, simplifying transmission construction, and allowing faster service and repair and reduced service and repair costs. This also allows the transmission to be more compact in design, since the transmission housing does not have to be enlarged to house the pump or fluid storage tank or sump.

In the preferred embodiment, the electric pump is mounted wherever space permits near the transmission within the vehicle engine compartment. Optimal locations may vary depending upon vehicle design. Front wheel drive automotive designs may dictate that the pump location be in the area of the firewall ahead of the windshield, for example. Rear wheel drive automotive designs may dictate that the pump be located along the inner fender skirt near a front wheel or wherever space permits. A real advantage of the invention is that the pump may be located where space permits alongside the engine or transmission. The pump draws transmission fluid from a storage tank holding a few quarts of fluid and send it through the torque converter and transmission. Fluid leaving the torque converter is directed through a heat exchanger for cooling and returned to the storage tank. Any excess fluid in the transmission is directed back to the pump and then to the storage tank for recirculation. Removing excess fluid from the transmission housing also improves transmission efficiency, eliminating power loss due to the drag on mechanical parts caused by excess fluid normally contained in a wet sump transmission.

The external pump design will make a significant improvement in operating efficiency and operating economy. Fuel mileage increases in the range of 20% to 50% may be expected depending on application, vehicle weight, engine displacement and other variables.

Any type of electric pump will work for this invention, including, but not limited to, vane, spur gear, gerotor, piston, centrifugal or turbine pumps.

Any type of prime mover can be used with this invention, whether it is a gasoline engine, diesel engine, hydrogen engine or power plant, electric motor or a hybrid powered vehicle.

• Provisional Patent
• Utility Patent

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