Abstract:
A control for an electric motor is utilized to avoid operation in or near the resonance frequencies for the electric motor and its associated system components. The resonance frequencies can be identified experimentally at the design stage, or during operation of a component and electric motor. During start-up, shutdown or frequency adjustment, the control drives the speed through the resonance frequency zones more rapidly, and also avoids operation in or near those resonance frequencies during steady state operation. In disclosed embodiments, the electric motors are associated with fans, pumps and compressors in a refrigerant system.
Abstract:
A hermetic compressor for positive displacement is disclosed whose airtight housing is specially altered so that its natural frequencies of vibration are distributed at frequencies above 4200 Hz and whose “capacitance density” is greater than 160 W/L.
Abstract:
A piezoelectric microblower includes a vibrating plate including a piezoelectric element and arranged to be driven in a bending mode by applying a voltage of a predetermined frequency to the piezoelectric element, and a blower body arranged to fix both ends or a periphery of the vibrating plate and to define a blower chamber between the blower body and the vibrating plate, an opening being provided in a portion of the blower body facing a central portion of the vibrating plate. In a portion of the blower chamber corresponding to the central portion of the vibrating plate, a partition is provided around the opening and a resonance space is defined inside of the partition. A size of the resonance space is set such that a driving frequency of the vibrating plate and a Helmholtz resonance frequency of the resonance space correspond to each other.
Abstract:
A method and apparatus for minimizing the amplitude of mechanical vibrations of a mechanical apparatus including a linear, freely reciprocating, prime mover coupled to and driving a reciprocating mass of a driven machine in reciprocation at a driving frequency. The coupled prime mover and driven machine have a spring applying a force upon the reciprocating mass to form a resonant main system having a main system resonant frequency of reciprocation. A driving frequency range over which the driven machine operates at an acceptable efficiency of operation is determined and stored. A parameter of the operation of the mechanical apparatus, such as the amplitude of vibrations or an operating temperature, is sensed and the prime mover is driven in response to the sensed parameter at a driving frequency that is offset from the main system resonant frequency of reciprocation, is within the driving frequency range of acceptable efficiency of operation and reduces or minimizes the amplitude of mechanical vibration of the mechanical apparatus under existing operating conditions.
Abstract:
Apparatus and method for selectively determining the resonant frequency of a gas compressor including a compressor drive motor and a muffler in a generally spaced relationship, and an apparatus mechanically linking the compressor drive motor and the muffler. The apparatus as disclosed in one embodiment includes two conical frustums as wedge members, each having an axial bore accommodating a single non-resilient shaft for joining the conical frustums such that the shaft may be adjusted to force the wedge members closer together, biasing the muffler with respect to the compressor drive motor, and thereby adjusting the resonant frequency of the compressor structure to a determined resonant frequency.
Abstract:
The invention in question pertains to the technological field of refrigeration compressors. A hermetic compressor for positive displacement is disclosed whose airtight housing is specially altered so that its natural frequencies of vibration are distributed at frequencies above 4200 Hz and whose "capacitance density" is greater than 160 W/L.
Abstract:
A driving unit and control method for a reciprocating compressor for controlling a frequency of input power so that an operational frequency of the compressor follows a resonant frequency, which varies depending on a variation of the load applied to the compressor. The reciprocating compressor includes an inverter to adjust the frequency of the input power, so that the frequency of the input power is set at a value corresponding to the resonant frequency by the inverter. The resonant frequency is set in a range of 60% to 90% of the normal power frequency. The compressor further includes a controller to control the frequency of the input power so that the operational frequency of the compressor follows the resonant frequency, which varies depending on the operation of the compressor.
Abstract:
[Object] To provide a piezoelectric microblower that can be made compact while still attaining good blower characteristics. [Solution] In part of a blower chamber 4 corresponding to a central portion of a vibrating plate 50, a resonance space 34 is formed by providing a partition 33 around an opening 31 and the size of the resonance space 34 is set such that the driving frequency of the vibrating plate 50 and the Helmholtz resonant frequency of the resonance space 34 correspond to each other. A gap δ is formed between the partition 33 and the vibrating plate 50 so that there is no contact therebetween when the vibrating plate is displaced. An increase in the flow rate can be attained by utilizing resonance of air.
Abstract:
A driving unit and control method for a reciprocating compressor for controlling a frequency of input power so that an operational frequency of the compressor follows a resonant frequency, which varies depending on a variation of the load applied to the compressor. The reciprocating compressor includes an inverter to adjust the frequency of the input power, so that the frequency of the input power is set at a value corresponding to the resonant frequency by the inverter. The resonant frequency is set in a range of 60% to 90% of the normal power frequency. The compressor further includes a controller to control the frequency of the input power so that the operational frequency of the compressor follows the resonant frequency, which varies depending on the operation of the compressor.