Hydraulic Pump Port Shape Optimization for Suction Capacity

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Solution Overview

Problem

Conventional axial-type hydraulic pumps experience a reduction in suction capacity when shifting from a discharging process to a suction process due to increased residual pressure inside the cylinder, which affects rotational efficiency and torque efficiency.

Innovation Solution

The design incorporates a cylinder block with annular band-shaped ports that do not include top or bottom dead points, and a residual pressure release port on the valve plate, allowing for increased rotation assistance while maintaining suction capacity by optimizing the opening shapes of the ports to enhance communication areas during the suction process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the rotation assist region is increased in length to improve rotational efficiency, then the rotational torque efficiency is improved, but the suction starting time is delayed and the suction capacity is reduced

Engineering Contradiction:

Improverotational torque efficiencyVSAvoidsuction capacity

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The suction port is divided into two separate opening portions: a first opening portion that communicates with the cylinder bore at the suction starting time, and a second opening portion that communicates with the cylinder bore after the piston passes the bottom dead point. This segmentation allows the suction process to occur in two stages, enabling the rotation assist region to be extended while maintaining adequate suction capacity through the second opening portion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first opening portion of the suction port is positioned to enable preliminary suction action before the piston reaches the bottom dead point. This preliminary suction ensures that the cylinder bore is partially filled with working oil in advance, compensating for the delayed suction starting time caused by the extended rotation assist region, thereby maintaining overall suction capacity.

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If a residual pressure extraction hole is provided to reduce pressure change during discharging to suction process, then the pressure equalization is improved, but the rotational efficiency is reduced due to loss of rotation assistance

Engineering Contradiction:

Improvepressure equalizationVSAvoidrotational efficiency

Core Design Contradiction:

Stability of the object's compositionVSPower

Solution Approach 1:

Instead of extracting residual pressure through a hole in the conventional location, the invention extracts and utilizes the residual pressure by positioning the suction port opening portions to communicate with the cylinder bore at specific rotational positions. The residual pressure is taken out at the optimal point (after bottom dead point passage) rather than immediately, preserving rotation assistance during the critical transition phase.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The residual pressure inside the cylinder bore, which traditionally causes harmful pressure equalization that reduces rotation assistance, is converted into a beneficial force. By timing the suction port communication to occur after the piston passes the bottom dead point, the residual pressure continues to assist rotation during the early suction phase, transforming the harmful pressure equalization into useful rotation assistance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design effectively suppresses the reduction in suction capacity while maintaining increased rotation assistance capability by optimizing port shapes and adding a residual pressure release port, ensuring efficient energy transfer and reduced pressure differences during the suction process.

Implementation Method 1

causes the high-pressure working oil inside the cylinders to return to the suction port when shifting from the discharging process to the suction process

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

each of the pistons reciprocates in the corresponding cylinder of the cylinder block, and sucks/discharges a working oil by moving axially

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentUS10018174B2Hydraulic pump/motor

Publication Date: 2018.07.10 KOMATSU LTD

AI summary

An axial-type hydraulic pump/motor in which a cylinder block with a plurality of cylinder bores formed around a rotation axis slides with respect to a valve plate that has a valve plate discharge port and a valve plate suction port, and controls the amount of reciprocation of a piston in each cylinder bore depending on the inclination of a swash plate. Based on the rotational direction of the cylinder block, an opening shape of an end portion on the front side in the rotational direction of a cylinder port and an opening shape of an end portion on the rear side in the rotational direction of the valve plate suction port PB1 have the same shape or partially have the same shape.