Obviousness

Obviousness Analysis of U.S. Patent No. 11,374,508 under 35 U.S.C. § 103

This analysis evaluates whether the invention claimed in U.S. Patent No. 11,374,508 (the '508 patent) would have been obvious to a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention. The standard for obviousness under 35 U.S.C. § 103 prevents the patenting of an invention if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious to a PHOSITA.

For the purpose of this analysis, a PHOSITA is considered to be an engineer with a degree in mechanical or electrical engineering and several years of experience in the design and development of electric or hybrid vehicle powertrains, including motor control systems and transmission technologies.

The independent claims (1, 7, and 12) of the '508 patent are directed to a dual-motor electric drive system. The key features are:

1. A specific powertrain architecture including a first motor, a transmission, a second motor, and a power split device comprising "one or more planetary sets."
2. An Energy Management System (EMS) that executes a specific control strategy: using only the first motor for low-demand modes (starting, cruising) and engaging both motors for high-demand modes (accelerating, uphill driving).

A strong case for obviousness can be made by combining the teachings of U.S. Patent No. 9,800,182 (Zhou '182) with U.S. Patent Application Publication No. 2011/0237385 A1 (Sato '237385).

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Primary Combination: Zhou '182 in view of Sato '237385

1. What Zhou '182 Discloses

Zhou '182, which is the parent patent to the '508 patent, discloses nearly all elements of the claimed invention. It serves as the foundational prior art reference. Specifically, Zhou '182 teaches:

• A dual-motor electric drive system: The system includes a first AC drive device (20) and a second AC drive device (22), which are analogous to the first and second electric motors of the '508 patent claims (FIG. 2).
• A Power Split Device: Zhou '182 explicitly discloses a power split device (19) that is mechanically coupled to both AC drive devices to combine their mechanical torque and deliver it to a single load (23) (FIG. 2).
• A Transmission Device: The specification of Zhou '182 discloses an optional transmission device (21) that can be placed "between the first AC drive device 20 and the first mechanical terminal 32 of the power split device 19" (Col. 5, ll. 62-64). This describes the exact mechanical arrangement claimed in the '508 patent.
• An Energy Management System (EMS) with Mode-Based Control: Zhou '182 describes an EMS (17) that controls the system based on the vehicle's operating mode. The specification details different modes including "a starting mode, an accelerating or uphill mode, a cruising mode, and a regenerative or braking mode" (Col. 6, ll. 32-35). It further describes enabling both motors for heavy loads (accelerating) and potentially only one for light loads, which is the core of the claimed control strategy. For example, it discusses a "light load" scenario where the second motor could even act as a generator to charge the ESS (Col. 5, ll. 50-56), implying single-motor propulsion.

2. The Missing Element in Zhou '182

The primary element specified in the '508 claims that is not explicitly required by the broadest disclosures in Zhou '182 is that the power split device (19) must comprise "one or more planetary sets." While the '508 specification (which shares its disclosure with the '182 patent) does mention planetary sets in the context of one embodiment (FIG. 4), the claims of the '508 patent make this a required limitation for the invention as a whole. Zhou '182, in its general description of FIG. 2, only describes the power split device as containing "one or more gears 35" (Col. 5, ll. 34-36), which is a broader, more generic term.

3. What Sato '237385 Teaches

Sato '237385 remedies this deficiency. It discloses a vehicle drive device, specifically for hybrid vehicles, that teaches the utility and implementation of a planetary gear set for power management. Sato explicitly teaches:

• A drive system with two motor-generators (MG1, MG2).
• A "power splitting mechanism" that is explicitly identified as a planetary gear unit (Abstract;). This planetary gear set is used to distribute and combine torque from the engine and the two motors.
• A control unit that manages the operation of the motors based on the vehicle's "running state" to improve efficiency.

4. Motivation to Combine and Reasonable Expectation of Success

A PHOSITA, starting with the dual-motor architecture and control strategy taught by Zhou '182, would have been motivated to implement the "power split device (19)" using a planetary gear set as taught by Sato '237385 for the following reasons:

• Solving a Known Problem with a Known Solution: The function of Zhou's "power split device" is to combine torque from two power sources. A PHOSITA would immediately recognize that planetary gear sets are a standard, well-known, and highly efficient mechanical solution for this exact purpose. The use of planetary gear sets in automotive transmissions and hybrid power-split devices (e.g., in Toyota's own well-established Hybrid Synergy Drive) was ubiquitous in the art by the 2012 priority date.
• Predictable Results: Sato demonstrates the successful use of a planetary gear set to manage power flows between two electric motors and a drive shaft. A PHOSITA would have a very high, if not certain, expectation of success in replacing Zhou's generic "gears 35" with Sato's planetary gear unit. This is a substitution of one known mechanical element for another to perform its well-known function, resulting in a system that is merely the sum of its parts.
• Design Choice: The selection of a specific gear configuration to implement a power split function is a matter of routine engineering and design choice. Choosing a planetary gear set, a known and optimized solution for this application, over other potential gear arrangements would have been an obvious choice to a skilled artisan seeking to create a compact, robust, and efficient system.

Conclusion on Obviousness

The combination of Zhou '182 and Sato '237385 teaches every element of the independent claims of the '508 patent.

• Zhou '182 provides the complete blueprint: a dual-motor EV architecture, the precise placement of a transmission on the first motor line, a power split device, and an EMS that uses a mode-based control strategy (single motor for cruise/start, dual motor for acceleration/uphill).
• Sato '237385 provides the specific, missing detail: the implementation of the power split device using one or more planetary gear sets, a common practice in the field.

A person of ordinary skill in the art would have been motivated to combine these teachings to achieve a more specific, concrete design of the system disclosed by Zhou '182, and would have reasonably expected the resulting system to function as claimed. Therefore, independent claims 1, 7, and 12 of U.S. Patent No. 11,374,508 appear to be obvious under 35 U.S.C. § 103.