Abstract: Once it is determined in Step S2 that a corner has been detected, a control unit causes a body to perform a reciprocating motion and initiate corner cleaning in Step S3. Then, once it is determined in Step S4 that a rubbish detection sensor detects no rubbish, the corner cleaning is terminated in Step S6. Once it is determined in Step S4 that the rubbish detection sensor detects rubbish, the corner cleaning continues to be executed by the body being caused to perform the reciprocating motion in Step S5. In other words, an autonomous travel-type cleaner is realized that can remove a large amount of the rubbish accumulating at the corner by causing the body to perform the reciprocating motion.

Abstract: Once it is determined in Step S2 that a corner has been detected, a control unit causes a body to perform a reciprocating motion and initiate corner cleaning in Step S3. Then, once it is determined in Step S4 that a rubbish detection sensor detects no rubbish, the corner cleaning is terminated in Step S6. Once it is determined in Step S4 that the rubbish detection sensor detects rubbish, the corner cleaning continues to be executed by the body being caused to perform the reciprocating motion in Step S5. In other words, an autonomous travel-type cleaner is realized that can remove a large amount of the rubbish accumulating at the corner by causing the body to perform the reciprocating motion.

Abstract: An inverter control device of the present invention operates by synchronous commutation in which a commutation signal waveform is output with an electric angle of less than 180 degrees at a predetermined frequency according to a target rotation speed of a brushless DC motor. In order to maintain an induced voltage phase of a brushless DC motor at a predetermined phase with respect to an output voltage of an inverter circuit unit, even in an operation by the synchronous commutation, the output voltage of the inverter circuit unit is changed according to a change in state of the induced voltage phase of the brushless DC motor to continue a running state of the motor. Therefore, a more stable motor operation can be performed during synchronous running by the forced commutation.

Abstract: An inverter controller for driving a brushless DC motor, of which rotor is provided with permanent magnets, includes an inverter circuit, a position sensing circuit, a DC voltage sensor, and a conduction angle controller. The inverter circuit is connected to the brushless DC motor for driving this motor. The position sensing circuit senses a rotor position with respect to a stator from an induction voltage of the brushless DC motor. The DC voltage sensor senses a voltage value of a DC power voltage supplied to the inverter circuit. The conduction angle controller changes a conduction angle of the inverter circuit within a range less than 180 degrees in electric angles in response to a rate of change in the DC power voltage.

Abstract: An inverter controller reduces a conduction angle of inverter circuit (204) within a range greater than 120 degree in electric angles when a time difference between intervals between each of position sensing and a total time of a time from an occurrence of a position sensing signal until the start of a commutation work to be done by inverter circuit (204) plus a time duration of a spike voltage becomes shorter than a predetermined reference time. This reduction of the conduction angle allows increasing a position sensible range, so that a position of magnetic poles of a rotor cannot be missed. The inverter controller thus can prevent a motor from falling into out-of-sync caused by a change in load or in voltage.

Abstract: An inverter controller for driving a brushless DC motor, of which rotor is provided with permanent magnets, includes an inverter circuit, a position sensing circuit, a DC voltage sensor, and a conduction angle controller. The inverter circuit is connected to the brushless DC motor for driving this motor. The position sensing circuit senses a rotor position with respect to a stator from an induction voltage of the brushless DC motor. The DC voltage sensor senses a voltage value of a DC power voltage supplied to the inverter circuit. The conduction angle controller changes a conduction angle of the inverter circuit within a range less than 180 degrees in electric angles in response to a rate of change in the DC power voltage.

Abstract: An inverter circuit includes a temperature measuring section for measuring a temperature of switching elements forming a powering section, a motor speed detector for detecting a speed of a motor, a carrier frequency determiner for determining a carrier frequency based on a temperature of the switching elements and a speed of the motor, and an output waveform determining circuit for determining a duty in response to a load applied to the motor and for switching a carrier frequency.

Abstract: An inverter circuit includes a temperature measuring section for measuring a temperature of switching elements forming a powering section, a motor speed detector for detecting a speed of a motor, a carrier frequency determiner for determining a carrier frequency based on a temperature of the switching elements and a speed of the motor, and an output waveform determining circuit for determining a duty in response to a load applied to the motor and for switching a carrier frequency.

Abstract: When a lock detector detects a locked state of a DC motor in a starting stage, a torque increasing circuit immediately selects a starting sequence pattern of an output torque that is greater in magnitude by one preselected step, and outputs the selected output torque to a starting sequence controller, so that a compressor can be restarted speedily without repeating starting failures. A compressor, driven by a DC motor, has a shell of an internal pressure approximately equal to the pressure of an inhalation gas. An inverter is provided to make the speed of the DC motor variable. A rotational frequency setting circuit sets the rotational frequency of the DC motor to a frequency that is not greater than the frequency of a commercial power source when the internal temperature of a refrigerator is stabilized. By this construction, the power consumption can be remarkably reduced.

Abstract: When a lock detector detects a locked state of a DC motor in a starting stage, a torque increasing circuit immediately selects a starting sequence pattern of an output torque that is greater in magnitude by one preselected step, and outputs the selected output torque to a starting sequence controller, so that a compressor can be restarted speedily without repeating starting failures. A compressor, driven by a DC motor, has a shell of an internal pressure approximately equal to the pressure of an inhalation gas. An inverter is provided to make the speed of the DC motor variable. A rotational frequency setting circuit sets the rotational frequency of the DC motor to a frequency that is not greater than the frequency of a commercial power source when the internal temperature of a refrigerator is stabilized. By this construction, the power consumption can be remarkably reduced.

Abstract: When a lock detector detects a locked state of a DC motor in a starting stage, a torque increasing circuit immediately selects a starting sequence pattern of an output torque that is greater in magnitude by one preselected step, and outputs the selected output torque to a starting sequence controller, so that a compressor can be restarted speedily without repeating starting failures. A compressor, driven by a DC motor, has a shell of an internal pressure approximately equal to the pressure of an inhalation gas. An inverter is provided to make the speed of the DC motor variable. A rotational frequency setting circuit sets the rotational frequency of the DC motor to a frequency that is not greater than the frequency of a commercial power source when the internal temperature of a refrigerator is stabilized. By this construction, the power consumption can be remarkably reduced.

Abstract: The same number of grooves 20 through 27 are provided in end surfaces 19a and 19b of a roller 19. The grooves 20 through 27 have communicating portions 20a through 27a which communicate with an inner peripheral side of the roller 19 and sealed portions 20b, 20c, 20d, 20e, 20f through 27b, 27c, 27d, 27e and 27f each of whose cross-sectional area decreases. Accordingly, the cross-sectional area is decreased in direction in which a lubricating oil flows, and a plurality of oil pressures can thus be obtained. This results in a fixed clearance of roller 19.