Twin Pump Casing Asymmetry for Cost Reduction

The patent applies asymmetry by intentionally designing the discharge passage portions of the first and second pumps to have different shapes. Specifically, the discharge passage of the first pump extends in a first direction while the discharge passage of the second pump extends in a second direction opposite to the first direction. This asymmetric design allows both pumps to be rotated in opposite directions while maintaining similar performance characteristics, thereby resolving the contradiction between performance balance and device complexity.

The asymmetric discharge passage design allows the use of identical pump bodies for both pumps while accommodating opposite rotation directions. By making only the discharge passage portions different (extending in opposite directions), the patent reduces the variety of components that need to be stocked, thereby resolving the contradiction between performance balance and stock requirements.

The patent applies local quality by making only specific portions of the pump casings different - specifically the discharge passage portions. The majority of the pump casing structure remains identical, allowing for standardized manufacturing and cost reduction. However, the discharge passages are locally modified to extend in opposite directions, which compensates for the performance differences caused by opposite rotation and maintains reliability.