Hydraulic Piston Pump With Varied Displacement for Sound Shaping
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Solution Overview
Problem
In vehicles without combustion engines, the noise emitted by hydraulic pumps becomes more noticeable due to the lack of sound masking by internal combustion engines, and existing noise reduction methods fail to alter the sound character to be both pleasant and audible.
Innovation Solution
A hydraulic piston pump with pistons of varying output pressures or flows is designed, altering the frequency distribution and sound character by using pistons of different sizes, shapes, or stiffness to create a more pleasant audible operation feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise reduction methods are used to reduce the noise level from the hydraulic pump, then the noise level is reduced, but the sound character remains sharp and unpleasant without providing desirable operational feedback
Solution Approach 1:
The patent applies parameter changes by varying the displacement volume of individual pistons within the hydraulic pump. By changing the geometric parameters (piston area, stroke length) of different pistons, the patent creates different pressure impulse patterns that modify the sound character. This allows the sound to remain audible and provide operational feedback while reducing the sharp, unpleasant characteristics of conventional pumps with identical pistons.
Solution Approach 2:
The patent implements local quality by giving each piston different displacement characteristics rather than using uniform pistons throughout the pump. Specific pistons are designed with different areas or stroke lengths to create localized variations in pressure generation. This local differentiation creates a more complex, less sharp sound profile while maintaining overall pump functionality and providing desirable operational feedback.
2Ease of manufacture
If identical pistons are used in the hydraulic pump, then the pump structure is simple and manufacturing is easier, but the sound character becomes sharp and unpleasant with prominent harmonic overtones
Solution Approach 1:
The patent applies asymmetry by deliberately designing pistons with different displacement volumes instead of using symmetric, identical pistons. The different piston sizes or stroke lengths create asymmetric pressure generation patterns that result in a less sharp sound character. This asymmetric design breaks the regular harmonic patterns produced by identical pistons, reducing the unpleasant tonal quality while remaining manufacturable.
Solution Approach 2:
The patent changes the geometric parameters of individual pistons (area, stroke length, or combination) to create variations in displacement volume. These parameter changes are implemented during manufacturing by producing pistons with different dimensions, which is feasible through standard machining processes. The result is a pump with varied piston characteristics that produces a more pleasant sound profile.
3Power
If the hydraulic pump operates at higher rotational speed to increase power output, then the power output increases, but the noise from the pump becomes more noticeable due to lack of engine masking
Solution Approach 1:
The patent changes the operational parameters of the pump by varying the displacement volume of individual pistons. This creates a more complex pressure waveform with reduced sharpness and less prominent harmonics. When the pump operates at higher speeds to increase power output, this modified pressure pattern ensures the noise remains less noticeable and more pleasant, even without the masking effect of an internal combustion engine.
Data Source
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AI summary
Hydraulic piston pump (1) comprising a plurality of pistons (8), where each piston is arranged in a cylinder barrel (10), where at least one piston (8) is arranged to deliver a specific pressure or output flow that differs from the pressure or output flow delivered by the other pistons (8).