Variable Displacement Pump Control for Noise Suppression

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Solution Overview

Problem

Variable displacement pumps in vehicles generate untoward noises when started after a period of inactivity, particularly at low temperatures, due to the flow of hydraulic oil through a strainer with negative pressure and potential foreign matter, leading to noise issues.

Innovation Solution

A control system for the variable displacement pump that switches to a partial capacity operation based on drive source rotational speed and hydraulic oil temperature after starting, and transitions to full capacity when hydraulic pressure reaches a predetermined level, minimizing negative pressure and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the variable displacement pump operates at full capacity immediately after engine start, then the hydraulic pressure builds up quickly, but untoward noises are generated due to high flow rate through the strainer at low temperatures

Engineering Contradiction:

Improvehydraulic pressure build-up speedVSAvoiduntoward noises

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The pump operates in two dynamic modes: full capacity mode for rapid hydraulic pressure build-up, and half capacity mode for noise suppression. The system dynamically switches between these modes based on operating conditions (engine speed, oil temperature, hydraulic pressure), resolving the contradiction between quick pressure build-up and noise generation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The discharge flow rate parameter is changed from full capacity to half capacity based on temperature and pressure conditions. By adjusting this parameter, the system reduces flow rate through the strainer at low temperatures to suppress noises, while maintaining full flow when temperatures are adequate

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If the variable displacement pump operates at partial capacity to suppress noises, then the hydraulic pressure build-up is delayed, but the untoward noises are effectively suppressed

Engineering Contradiction:

Improveuntoward noisesVSAvoidhydraulic pressure build-up time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The pump operates periodically in half capacity mode during the critical initial period after engine start when noises are most problematic. Once hydraulic pressure reaches the threshold or oil temperature increases, the system transitions to full capacity mode, creating a periodic operation pattern that suppresses noises during vulnerable periods while minimizing delay

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system performs preliminary noise suppression operation at half capacity before the hydraulic system becomes fully pressurized and before oil temperature rises. This preliminary action prevents noise generation during the most critical period, and the transition to full capacity afterward minimizes the overall time loss

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If the pump maintains full capacity operation, then the discharge flow rate is maximized for timely hydraulic pressure build-up, but the negative pressure downstream of the strainer increases causing noise

Engineering Contradiction:

Improvedischarge flow rateVSAvoidnegative pressure downstream of strainer

Core Design Contradiction:

Quantity of substanceVSStress or pressure

Solution Approach 1:

The pump operates at partial capacity (half capacity) during low-temperature conditions, providing just enough discharge flow rate to build hydraulic pressure without excessively increasing the flow through the strainer. This partial action reduces negative pressure downstream of the strainer and suppresses noise, while still achieving necessary hydraulic pressure build-up

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9477231B2Control system for variable displacement pump

Publication Date: 2016.10.25 HONDA MOTOR CO LTD

AI summary

A control system for a variable displacement pump driven by a drive source for driving a vehicle is provided. The variable displacement pump pressurizes hydraulic oil, and is switchable between a full capacity operation in which a discharge flow rate is maximized and a partial capacity operation in which the discharge flow rate is lower than that in the full capacity operation. It is determined whether an operation for starting the drive source has been performed. A rotational speed of the drive source and a temperature of the hydraulic oil are detected. When the rotational speed of the drive source is equal to or higher than a predetermined rotational speed and the hydraulic oil temperature is equal to or lower than a predetermined temperature, immediately after the operation for starting the drive source is performed, the partial capacity operation of the variable displacement pump is performed. This control suppresses generation of untoward noises caused by the operation of the variable displacement pump when starting to drive the vehicle.