| Low ripple gear pump/motor -> Monitor Keywords |
|
|
  Low ripple gear pump/motorUSPTO Application #: 20070201989Title: Low ripple gear pump/motor Abstract: A gear pump system comprises a gear pump having an inlet, an outlet, and at least one rotating gear for pumping fluid from the inlet to the outlet and producing an output flow characterized by pressure pulses arising from the geometry of the teeth of the gear; and at least one valve operative to vary the output flow in timed relation to the rotation of the gear for counteracting the pressure pulses, thereby to reduce the amplitude of the pressure pulses. (end of abstract) Agent: Don W. Bulson (parker Hannifin) Renner, Otto, Boisselle & Sklar, LLP - Cleveland, OH, US Inventors: Jonathan Zhu, Lisa Furches, Marty Hudak, Frank Iannizzaro USPTO Applicaton #: 20070201989 - Class: 417310000 (USPTO) Related Patent Categories: Pumps, With Condition Responsive Pumped Fluid Control, Pressure Responsive Relief Or Bypass Valve, Rotary Expansible Chamber Pump The Patent Description & Claims data below is from USPTO Patent Application 20070201989. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60/726,568 filed Oct. 14, 2005, which is hereby incorporated herein by reference. FIELD OF THE INVENTION [0002] The invention herein described relates to a low ripple gear pump/motor system and method, and more generally to an apparatus and method for reducing if not eliminating ripple from a fluid circuit. BACKGROUND [0003] Many gear pumps (and motors), because of the geometry of the gear teeth, inherently produce a small flow pulse for each gear tooth as the gears rotate, and this in turn produces pressure pulses. Such flow/pressure pulses are commonly referred to as ripple. The ripple can produce undesirable noise and vibration. The noise and/or vibration can become excessive if the ripple excites hydraulic resonance in the hydraulic system. [0004] Increasing the number of gear teeth decreases flow ripple amplitude, but this technique has limitations. Three alternative technologies that are used today for low noise hydraulic gear pumps are known as Dual Flank Contact, Split Gear, and Helical Gear. [0005] The Dual Flank Contact (DFC) design achieves low flow ripple by removing the backlash found in normal spur gears that provide single line contact. Zero backlash allows two-line contact thus increasing the frequency of pulsations while lowering the amplitude of the pulse. [0006] The Split Gear design achieves the same result as DFC, but this is achieved by timing a sliding set of gears onto an integral set of gears that are phased by one half tooth pitch. The two gear sets are separated by a wear plate, which allows them to function as two pumping elements. [0007] The Helical Gear Pump design is similar to a spur gear pump, except that the gears are made with an indexing angle such that each tooth is phased one full tooth pitch from one face to the other. The flow pulsation is drastically reduced as the teeth mesh. A drawback is that compensation must be made for the axial separating forces that are generated. Consequently, helical gears are rarely used for high pressure applications. SUMMARY OF THE INVENTION [0008] The present invention addresses the problem of ripple in a fundamentally different manner. Instead of modifying the source of the ripple as was done in the past, the ripple is removed by acting on the output flow of the pump in timed relation to the source of the ripple. More particularly, the ripple arising from the variable volume output/input of the gears of a gear pump/motor is counteracted by at least one valve that operates in timed sequence with the rotation of the gears. Preferably, a fast acting valve is employed and digitally pulse width modulated to vary the pump output flow in timed relation to rotation of gear teeth. The valve timing may be effected by any suitable means, such as by using position, speed, and/or pressure sensors. For example, a position sensor (i.e. proximity sensor) can be coupled to a rotating component of the pump to provide an output indicative of the position of the gears and, in particular, the position of at least one tooth of at least one gear. A respective fast acting valve can be controlled or timed to introduce a secondary pulse of flow "phased" with a ripple pulse. The valve may be controlled by a sensor, i.e. to "signal" a pressure peak and also a speed, to control the continued response of the fast acting valve. The speed of the fast acting valve versus the rotational speed of the pump will determine the "smoothness" of any remaining ripple. [0009] As will be appreciated, principles of the invention can be applied to virtually any pulsating flow source and thus has potential for retrofitting known pump designs that exhibit the ripple phenomena. Moreover, this can be effected in a relatively inexpensive and simple manner. In addition, principles of the invention can be applied to hydraulic gear motors to reduce torque ripple at the output of the motor. [0010] Accordingly, the invention provides a gear pump system comprises a gear pump having an inlet, an outlet, and at least one rotating gear for pumping fluid from the inlet to the outlet and producing an output flow characterized by pressure pulses arising from the geometry of the teeth of the gear; and at least one valve operative to vary the output flow in timed relation to the rotation of the gear for counteracting the pressure pulses, thereby to reduce the amplitude of the pressure pulses. [0011] More particularly, the valve may be operative to introduce secondary pulses of flow in timed relation to the pressure pulses to counteract the pressure pulses. The valve, for example, may be a pulse width modulated valve. A sensor may be provided for producing an output synchronous with the pressure pulses, and a controller may control the at least one valve to introduce into the flow passage secondary pulses of flow "phased" with the pressure pulses. [0012] The sensor may include a position sensor operatively coupled to the gears to provide a position output signal representative of the position of the gears, and/or a pressure sensor for sensing the pressure at the outlet of the pump. [0013] According to a more general aspect of the invention, a system for counteracting pressure pulses in a fluid circuit comprises a fluid circuit characterized by pressure pulses, and a flow control device for varying the flow in the fluid circuit in a manner that counteracts the pressure pulses, thereby to reduce the amplitude of the pressure pulses. The flow control device may include at least one valve operative to open and close in timed relation to the pressure pulses for controlling flow of fluid to or from the fluid circuit. The valve may be operative under the control of the controller to introduce into the fluid circuit secondary pulses of flow "phased" with the pressure pulses. [0014] According to still another aspect of the invention, a method for counteracting pressure pulses in a fluid circuit comprises the steps of using a sensor to provide an output synchronous with the pressure pulses, and operating a valve to vary the flow in the fluid circuit a function of the output of the sensor so as to vary the flow in fluid circuit in a manner that counteracts the pressure pulses, thereby to reduce the amplitude of the pressure pulses. [0015] According to a further aspect of the invention, a motor system and method are characterized by a hydraulic gear motor having an inlet for receiving an input flow of pressurized fluid, an outlet, and at least one rotating gear rotated by flow of fluid from the inlet to the outlet and producing an output torque characterized by torque pulses arising from the geometry of the teeth of the gear; and at least one valve operative to vary the input flow pressure in timed relation to the rotation of the gear for counteracting the torque pulses, thereby to reduce the amplitude of the torque pulses. [0016] Further features of the invention will become apparent from the following detailed description when considered in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0017] In the annexed drawings, [0018] FIG. 1 is a diagrammatic illustration of an exemplary pump system according to the invention; [0019] FIG. 2 is a diagrammatic illustration of another exemplary embodiment of a pump system according to the invention; and Continue reading... Full patent description for Low ripple gear pump/motor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Low ripple gear pump/motor 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 Low ripple gear pump/motor or other areas of interest. ### Previous Patent Application: Vacuum pump Next Patent Application: Discharge system for compressors Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Low ripple gear pump/motor patent info. IP-related news and info Results in 0.69859 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , |
||
