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Pump for brake systemRelated Patent Categories: Pumps, Expansible Chamber Type, Pumping Member Position Controlled PortPump for brake system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070116586, Pump for brake system. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of Korean Patent Application No. 2005-0112256, filed on Nov. 23, 2005 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a pump for a brake system, and, more particularly, to a pump for a brake system for achieving an improvement in oil pumping performance and pump assembling efficiency. [0004] 2. Description of the Related Art [0005] Generally, a brake system has the purpose of efficiently preventing a wheel slip caused upon braking, quick start, or sudden acceleration of a vehicle. The brake system includes a plurality of solenoid valves to control a braking hydraulic pressure to be transmitted to hydraulic brakes of vehicle wheels, a pair of low-pressure and high-pressure accumulators to temporarily store an oil discharged from the hydraulic brakes, a pair of pumps provided between the low-pressure and high-pressure accumulators, the pumps being operated by a motor, and an ECU to control operations of the solenoid valves and motor. All the above elements are received in a modulator block made of aluminum. [0006] In particular, the pumps of the brake system serve to forcibly pump the oil stored in the low-pressure accumulator or master cylinder to the high-pressure accumulator, so as to transfer the oil to the hydraulic brakes or master cylinder. [0007] Many patents, including Korean Patent Laid-open No. 10-2005-0050168 and Korean Patent Registration No. 10-0381592 filed by the applicant of the present invention, disclose conventional pumps for a conventional electronically controlled brake system. [0008] Explaining the conventional electronically controlled brake system in brief, it includes a booster and master cylinder associated with a brake pedal, a plurality of solenoid valves to control a braking hydraulic pressure to be transmitted to hydraulic brakes installed at front and rear vehicle wheels, a low-pressure accumulator to temporarily store oil discharged from the hydraulic brakes, a pair of pumps to pump the oil in the low-pressure accumulator or master cylinder, a motor to drive the pair of pumps simultaneously, and a high-pressure accumulator having an orifice disposed at an exit side thereof to reduce a pressure pulsation of the oil compressed and discharged by operation of the pumps. All the above elements are received in a modulator block made of aluminum. The pair of pumps are operated by the single motor to have a predetermined phase difference, thereby compressing the oil in the low-pressure accumulator or master cylinder and pumping the compressed oil to the high-pressure accumulator. Herein, further detailed description of the brake system will be omitted because it is fully disclosed in the above mentioned patent documents related to the prior art. [0009] FIG. 1 illustrates a conventional pump for a brake system. The conventional brake system comprises a motor 10, a spindle 11 to be rotated by the motor 10, an eccentric shaft 12 to be eccentrically rotated by the spindle 11, a bearing 13 installed around the eccentric shaft 12, a piston 30 installed in a bore 21 formed in a modulator block 20 to perform reciprocating motions under the assistance of the bearing 13, the piston 30 having an inner oil flow path 31, an inlet valve 40 to open and close an exit side of the oil flow path 31 based on a position of the piston 30, and an outlet valve 60 provided at an open end of the bore 21, operations of the inlet and outlet valves 40 and 60 being contrary to each other. [0010] The modulator block 20 is formed with a suction port 22 and a discharge port 23. The suction port 22 is used to connect an entrance side of the oil flow path 31 defined in the piston 30 to a low-pressure accumulator (not shown) or master cylinder (not shown), and the discharge port 23 is used to connect the an entrance side of a high-pressure accumulator (not shown) to an exit side of the outlet valve 60. The discharge port 23 communicates with the bore 21. [0011] The inlet valve 40 for opening and closing the oil flow path 31 includes a valve opening/closing member 42 installed at an exit-side end of the oil flow path 31, a valve spring 43 to elastically push the valve opening/closing member 42 toward the exit side of the oil flow path 31, and a holder 44 configured to receive the valve opening/closing member 42 and valve spring 43. Also, a conical valve seat 41 is formed at an end of the piston 30 in the exit side of the oil flow path 31. The valve seat 41 is adapted to come into contact with or be spaced apart from the valve opening/closing member 42. [0012] A valve cover 50 is also installed in the bore 21. The piston 30 assembled, at one end thereof, with the inlet valve 40 is inserted in the valve cover 50. The outlet valve 60 is also inserted in the valve cover 50. The valve cover 50 defines a compression chamber 51 with the end of the piston 30 in accordance with the reciprocating motions of the piston 30. [0013] In the conventional pump having the above described configuration, if the motor 10 operates, the spindle 11 is rotated and thus, the eccentric shaft 12 is eccentrically rotated, causing rectilinear reciprocating motions of the piston 30. Thereby, as the inlet and outlet valves 40 and 60 perform opening and closing operations contrary to each other by a pressure variation in the bore 21, oil is compressed and pumped to the high-pressure accumulator (not-shown). [0014] Specifically, if the piston 30 moves toward the outlet valve 60, a pressure of the oil between the piston 30 and the outlet valve 60 rises, causing the inlet valve 40 to be closed and the outlet valve 60 to be opened. Thereby, the oil is pumped to the high-pressure accumulator (not shown) through the discharge port 23. [0015] On the other hand, if the piston 30 moves toward the bearing 13, the pressure of the oil between the end of the piston 30 and the outlet valve 60 falls, causing the inlet valve 40 to be opened and the outlet valve 60 to be closed. Thereby, the oil stored in the low-pressure accumulator (not shown) or master cylinder (not shown) is suctioned into a space between the piston 30 and the outlet valve 60, i.e. compression chamber 51, through the suction port 22 and oil flow path 31. [0016] In addition to the above described configuration, seal members 32 are provided to prevent any possible leakage of the oil from a gap between the piston 30 and the bore 21 during operation of the piston 30. [0017] However, the above described conventional brake system has many problems as follows. Firstly, since the bore 21 guides the reciprocating motions of the piston 30 and the seal members 32 move together with the piston 30, there is a problem in that the piston and bore may cause a gap therebetween due to their friction contact, and the gap may result in serious deterioration in sealing performance by the seal members. Secondly, the seal members have a limit in sealing effect because they are secured to the piston and adapted to move together with the piston. Thirdly, the conventional brake system suffers from low durability thereof due to wear of an inner portion of the bore, an outer portion of the piston, seal members, etc. Fourthly, the piston may be easily separated from the bore in a state wherein the motor, spindle, eccentric shaft, bearing, etc. are removed from the modulator block for the assembling or disassembling of the pump, and reassembling the piston into the bore is a very difficult and troublesome work. SUMMARY OF THE INVENTION [0018] The present invention has been made in order to solve the above problems. It is an aspect of the invention to provide a pump for a brake system which can achieve an increase in sealing performance between a piston and a bore as well as motion performance and durability of the piston, and can guarantee easy assembling of the piston into the bore. [0019] Consistent with one aspect, an exemplary embodiment of the present invention provides a pump for a brake system comprising: a bore formed in a modulator block and connected to a suction port and discharge port; a piston installed in the bore to perform rectilinear reciprocating motions, the piston comprising an oil flow path to move an oil suctioned through the suction port toward the discharge port; an inlet valve to open and close the oil flow path in accordance with the motions of the piston and an outlet valve to selectively allow the discharge of the compressed oil; and a fixing unit comprising a guide member provided around the piston to be coupled to the bore and adapted to guide the motions of the piston and a sealing member provided around the piston to be coupled to the bore and adapted to keep between the bore and the piston in an air-tightness state. [0020] The guide member and sealing member may be integrally formed with each other to constitute the fixing unit. [0021] The piston may have a protruding portion to be caught by the fixing unit, so as to prevent the piston from extending out of the bore beyond a predetermined length. Continue reading about Pump for brake system... Full patent description for Pump for brake system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Pump for brake system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Pump for brake system or other areas of interest. ### Previous Patent Application: Cam driven piston compressor apparatus Next Patent Application: Volume-metering pump device Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Pump for brake system patent info. 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