Attenuation of fluid borne noise from hydraulic piston pumps

Abstract

In many hydraulic systems, fluid borne noise is generated during operation due to the effects of the hydraulic piston pump. This fluid borne noise is transmitted to various structures of the hydraulic system which emit vibrations that create the largest portion of the system air borne noise. In the subject invention, an apparatus is provided for the attenuation of fluid borne noise. The apparatus includes a sensor arrangement operative to sense operating system parameters and deliver signals representative thereof to a microprocessor, a porting arrangement within the hydraulic piston pump that includes a secondary port, a fluid chamber, and first and second passageways interconnecting the secondary port, the fluid chamber, and a discharge passage. The microprocessor receives the signals from the sensor arrangement and directs electrical command signals to an electrically controlled valve mechanism disposed in the first and second passageways. The microprocessor and the valve mechanism operate to control fluid flow between the discharge passage, the fluid chamber, and the secondary port. By pressurizing fluid in the fluid chamber which in turn pre-pressurizes the piston port through the secondary port prior to the piston port entering the discharge passage, the flow required to pressurize the piston port prior to the piston port entering the discharge passage is spread over a larger range of piston port rotation.