US Patent 8162635 Low vibration pump

A liquid pump is provided in which pulsations can be properly absorbed even if the pump is driven at a high frequency. A pulsation absorbing unit for absorbing pulsation includes a pulsation absorbing housing disposed on a pump housing member, a second diaphragm attached to the pulsation absorbing housing member and defining a pulsation absorbing chamber communicating with a liquid outlet passage of a liquid pump unit, and a disc spring for biasing the second diaphragm toward the pulsation absorbing chamber.