• 한국정밀공학회지
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• 제14권8호
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• pp.146-154
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• 1997

Solenoid-folw control type ABS is used with a 'dump and reapply' pressure control arrangement instead of using 2/2 (normal open/close) solenoid valves in convensional systems(sol. -sol. control type), a flow control valve is used which replaces the (no) inlet valve. The flow control valve controls fluid flow providing a nearly constant reapply rate( .theta. ) after the dump plase of ABS operation. In this study, to investigate a characteristics of brake pressure by PWM control, test rig was consisted of ABS hydraulic modulator, digital controller, pneumatic power supply and brake master cylinder. For comparison with experi- mental results, system modelling and computer simulation were performed. As a result, experiment results showed fairly agreement with the simulation. Also, it is shown that the pressure gradient (tan .theta. ) is affected by pressure, frequency, duty ratio and expressed with an exponential funtion.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.569-572
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• 1995

In this study, a hydraulic modulator of solenoid-flow type ABS, the master sylinder, and the wheel cylinder are modeled and simulated for increasing pressure characteristics of the brake. Response can be predicted by external force of the the master sylinder and pulses to the solenoid valve as input. For a demonstration of simulation result, experiment is done under the same condition as simulation condition after experimental apparatus of 1/4 car model is constructed. When factors of flow control valve are changed, the effect of each factor to response, how to improve response, and the most critical factors are considered from simulated result of time constant.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.676-681
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• 2001

ABS is a safety device, which adds hydraulic system to the existing brake system to prevent wheel from locking, so we can obtain maximum braking force on driving. The hydraulic system to control braking pressure consists of sol-flow type using solenoid valve, flow control valve or consists of sol-sol type using two solenoid valve. In this paper, the hydraulic system in ABS is composed of sol type using a 3port-2position solenoid valve, and vehicle system is composed of 1/4 vehicle model. And slip ratio is controlled using PWM (Pulse-Width-Modulation) control algorithm. Braking friction coefficient and tracking friction coefficient which are described by slip ratio's function have maximum value when slip ratio has its value from 0.1 to 0.3. And slip ratio is controlled constantly in this boundary value even in the variation of road's condition in some boundary.