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Multi-piston pump and valve arrangementRelated Patent Categories: Pumps, Three Or More Cylinders Arranged In Parallel, Radial, Or Conical Relationship With Rotary Transmission Axis, Radial CylindersMulti-piston pump and valve arrangement description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070041850, Multi-piston pump and valve arrangement. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates in general to hydraulic pumps. [0003] 2. Description of Related Art [0004] A hydraulic brake system is one type of generally known brake system for vehicles. A vehicle hydraulic brake system typically has a master cylinder, a number of wheel brake cylinders, and a hydraulic pump with which brake fluid can be delivered from the master cylinder to the wheel brake cylinders. For example, the hydraulic pump may be used for hydraulic brake boosting. The hydraulic pump may also be used, in conjunction with a series of valves in a hydraulic control unit (HCU) for antilock braking system (ABS), traction control (TC), and vehicle stability control (VSC) functions. One known method for carrying out these functions is to program an electronic control unit (ECU) to reduce pressure in the wheel brake cylinders by way of controlling (solenoid) valves in the HCU. In one known system the intake side of the hydraulic pump is connected to the wheel brake cylinders and the pressure side of the hydraulic pump is connected to the master cylinder. A vehicle hydraulic brake system of this kind has been disclosed by DE 195 01 760 A1. [0005] It is generally known to use a dual piston pump for the hydraulic pump in such a system. The dual piston pump typically includes pistons disposed opposite each other in a boxer arrangement, which are driven by a common cam disposed between the two pistons. The two pistons operate in anti-phase, i.e. while one of the two pistons is executing a delivery stroke, the other piston is executing a return stroke. The delivery stroke is the stroke in which the piston decreases the volume of a displacement chamber in a cylinder of the piston pump and thus displaces fluid from the piston pump. In the return stroke, the volume of the displacement chamber is increased again; this stroke is also often called the intake stroke. Due to their oscillating operation, piston pumps have an oscillating intake volume flow and cause pressure pulsations on the intake side, which have repercussions on the master cylinder and produce an unpleasant sensation in a foot brake pedal and generate clearly audible noise. Both of these are undesirable, particularly if the hydraulic pump is used for hydraulic brake boosting, i.e. is operated with each braking maneuver. These are also undesirable during antilock braking, traction control, and vehicle stability control. Therefore, it is desirable to reduce the pressure pulsations. It is also known to embody the pistons of the piston pump as stepped pistons which have the advantage of aspirating brake fluid during both the delivery stroke and the return stroke. A stepped piston has the advantage over a simple piston of a more uniform intake volume flow with a reduced amplitude and a doubled frequency. U.S. Pat. No. 6,446,435 describes a motor driven pump using an even number of stepped pistons to reduce amplitudes of pressure pulsations in the inlet of the pump. [0006] In operation of the pump, it is desirable that the pump be reliable, relatively low cost to manufacture, operate with low noise and vibration, and minimize pressure pulsations in the brake system that are felt by the driver of the vehicle. BRIEF SUMMARY OF THE INVENTION [0007] This invention relates in general to hydraulic pumps and more specifically to a multi-piston hydraulic pump and a valve arrangement. [0008] A first aspect of the present invention includes a multi-piston pump includes a housing defining a first plurality of N bores therein, where N is the number of bores in the first plurality. The bores of the first plurality of N bores are offset from one another. The housing defines a second plurality of N bores therein. The bores of the second plurality of N bores are offset from one another. Each bore of the second plurality of N bores is also offset from a corresponding bore of the first plurality of N bores. A substantially straight cylindrical piston is disposed in each of said bores for reciprocal movement along a longitudinal axis therein. The pistons in the first plurality of N bores are operable to induce fluid flow in a first hydraulic circuit. The pistons in the second plurality of N bores are operable to induce fluid flow in a second hydraulic circuit. [0009] In another aspect of the present invention, a valve arrangement includes a main valve body having a plurality of bores formed therein. The valve arrangement is suitable to form a portion of a multi-piston pump and includes first and second pluralities of non-stepped pistons disposed in the bores. The valve arrangement is suitable for controlling fluid flow in a hydraulic circuit. [0010] Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0011] FIG. 1 is a schematic circuit diagram of a vehicular brake system. [0012] FIG. 2 is a schematic representation of a six-piston pump in accordance with the present invention suitable for use in the vehicular brake system shown in FIG. 1. [0013] FIG. 3 is a cross-sectional view of a portion of the pump of FIG. 2 taken along line 3-3. [0014] FIG. 4 is an enlarged view of a portion of FIG. 3. [0015] FIG. 5 is a top view of the sleeve of FIGS. 3 and 5. [0016] FIG. 6 is a cross-sectional view of the sleeve of FIG. 5 taken along line 6-6 [0017] FIG. 7 is an enlarged view of a portion of FIG. 6 as indicated at circle 7. DETAILED DESCRIPTION OF THE INVENTION [0018] A vehicular brake system is indicated generally at 10 in FIG. 1. The system 10 includes valves and other components described below suitable to provide anti-lock braking (ABS), traction control (TC), and vehicle stability control (VSC) functions. [0019] In the system 10, a brake pedal 12 is connected to a master cylinder 14 to provide pressurized brake fluid to wheel brakes 16. The master cylinder 14 is in fluid communication with a master cylinder brake fluid reservoir 15. The reservoir 15 is a source of bake fluid for the master cylinder 14. [0020] A hydraulic control unit (HCU) 18 includes a housing having bores for receiving control valves and other components described below. Fluid passageways or conduits are provided between the bores to provide fluid communication between the valves and other components. Continue reading about Multi-piston pump and valve arrangement... Full patent description for Multi-piston pump and valve arrangement Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Multi-piston pump and valve arrangement 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 Multi-piston pump and valve arrangement or other areas of interest. ### Previous Patent Application: Piston-reciprocating gas compressor Next Patent Application: Pump assembly Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Multi-piston pump and valve arrangement patent info. 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