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Pulsation pressure decreased type pump for vehicle slip control system

Pulsation pressure decreased type pump for vehicle slip control system description/claims

The present application is based on, and claims priority from, Korean Application Serial Number 10-2007-0059757, filed on Jun. 19, 2007, the disclosure of which is hereby incorporated by reference herein in its entirety.

The present invention relates to a pump for a vehicle slip control system, and more particularly, to a pulsation pressure decreased type pump.

In general, a brake of a vehicle is used to stop a vehicle or reduce the speed of a vehicle by transmitting a braking pressure, which is a hydraulic pressure, to a wheel brake on the basis of the operation of a brake pedal. Since a running vehicle is forcibly stopped by the brake, the vehicle occasionally is slipped due to the braking pressure or road conditions during braking.

A brake, which electronically controls the braking pressure of the wheel brake, has been widely used to prevent the slip from occurring. That is, there have been widely used an ABS (Anti Lock Brake System), a TCS (Traction Control System) that prevents large slip from occurring on driving wheels during quick starting and accelerating, or an ESP (Electronic Stability Program) system that minimizes a difference between an intended direction and an actual direction of a vehicle in order to safely maintain a vehicle in the intended direction under any driving conditions.

An oil pump is driven by a motor and pumps oil in the above-mentioned electronically controlled brake systems. As the pump operates, a hydraulic circuit formed between a master cylinder and a wheel cylinder controls the flow of oil in a direction toward a wheel cylinder or in a reverse direction thereof.

However, when operating, the oil pump forming the entire brake hydraulic circuit sucks or discharges the oil by a piston that is reciprocated by the motor. In particular, when the pump discharges oil, pulsation is generated at an outlet of the pump. As the piston of a valve in the pump reciprocates, a plurality of pulsation is superposed and is increased to about 20 bar, which undesirably affects related components.

Embodiments of the present invention help overcome the drawbacks of the brake system and provide a pulsation pressure decreased type pump for a vehicle slip control system that includes an orifice provided on a discharge channel of a pump that discharges a working fluid using a piston reciprocated by a cam during operation. When the pump discharges the working fluid, the orifice related with an outlet check valve controls the amount of the working fluid, so that a pulsating pressure caused by pulsation superposition is decreased from 20 bar to 5 bar or less.

Further, embodiments of the present invention provide a pulsation pressure decreased type pump including an orifice, which is formed by pressing, so as to minimize manufacturing cost and time required to manufacture and machine the orifice. The orifice decreases a pulsating pressure, which is generated at an outlet when a pump discharges a working fluid, to 5 bar or less.

Furthermore, embodiments of the present invention provide a pulsation pressure decreased type pump including an orifice, which has a discharge channel directly formed therein and is directly fixed to a sleeve. Accordingly, a discharge channel does not need to be formed in a sleeve fixed to a cap, and the sleeve does not need to be machined for the assembling of the orifice.

In addition, embodiments of the present invention provide a pulsation pressure decreased type pump including an orifice, which is provided at an outlet in a pump and directly fixed to an end of a sleeve. Accordingly, since centering between the orifice and the sleeve does not need to be performed, it is possible to easily perform assembly.

A pulsation pressure decreased type pump according to an embodiment of the present invention includes a hollow sleeve. The sleeve is fixed to a pump housing, receives a working fluid through an inflow channel formed in a radial direction, and includes a channel formed inside an end thereof opposite to the inflow channel. A piston is elastically supported in the sleeve by an inner spring. The piston is reciprocated by the drive of the pump so as to allow the working fluid to flow into an inflow channel communicating with the inflow channel of the sleeve. An inlet check valve includes a ball, a check valve spring, and a cover. The ball blocks an outlet through which the working fluid flowing into the piston passes. The check valve spring is fixed to an outlet of the piston and elastically supports the ball. The cover receives the check valve spring, is fixed to the piston, and has a radial channel serving as an outlet for the working fluid. An outlet check valve includes a ball and a check valve spring. The ball is received in a cap fixed to an end of the sleeve, and opens or closes a passage of the working fluid discharged from the sleeve. The check valve spring is inserted into the cap so as to elastically support the ball. An orifice is provided between the sleeve and the cap fixed to the end of the sleeve, and changes the flow of the working fluid discharged from the sleeve so as to decrease a pulsating pressure of the working fluid caused by the reciprocation of the piston. An outflow channel is integrally formed with the orifice so that the working fluid discharged from the sleeve through the outlet check valve is guided to an outlet of the pump housing.

In addition, the orifice may include an annular body, fixation ends, and an outflow channel. The annular body has a central hole, with which the ball of outlet check valve 8 comes in close contact, at the center thereof. The fixation ends protrude from the annular body and are fitted to a stepped orifice fixing end formed at the end of the sleeve. An outflow channel guides the working fluid which is discharged from the sleeve through the annular body, to the outlet of the pump housing.

Further, the fixation ends may be composed of an upper fixation end and a pair of left and right lower fixation ends. The upper fixation end is bent to protrude toward one side of the annular body. The pair of left and right lower fixation ends is bent to protrude toward one side of the annular body at positions corresponding to an angle of about 120° from the upper fixation end.

Furthermore, left and right divided fixation ends, which are separated from each other and face each other, may be formed by cutting a central portion of the upper fixation end so that an outflow channel for guiding the working fluid discharged from the sleeve to the outlet of the pump housing is formed in the upper fixation end.

The outflow channel may include an inlet, a narrow portion, an extension portion, and a wide portion. The inlet is formed by cutting the annular body so as to allow the working fluid to flow. The narrow portion communicates with the inlet and decreases a flow width of the working fluid to increase the flow speed of the working fluid. The extension portion forms an end of the narrow portion and has a narrow width. The wide portion expands at the end of the extension portion.

The orifice may be integrally formed by pressing.

• Provisional Patent
• Utility Patent

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