Abstract: In order to protect a brushless motor, heat generated at a switching device, in response to an abnormality, activates a protection device. The protection device includes a connecting line communicating between a source supply line and the switching device. The protection device is provided near the switching device such that it can sense heat at the switching device with a high degree of sensitivity. Thus, when excessive heat is generated at the switching device, the protection device reaches a specific temperature, whereby the source supply line becomes cut off from the switching device, thereby immediately stopping the operation of the brushless motor.

Abstract: A brushless motor which includes an arrangement to prevent dielectric breakdown of electronic parts mounted on a control board. The breakdown is caused by a heat sink which becomes electrostatically charged. The potential at the heat sink, which contacts switching devices (for instance, FETS) of the brushless motor, is equalized with the potential at one side of a source line for a drive circuit formed on the control board that includes the switching device. As a result, when the heat sink becomes electrostatically charged, the charge at the heat sink can be discharged to the source line, thereby eliminating the above problem.

Abstract: A pulse width of a drive pulse of a brushless motor is modulated in correspondence to a setting signal for setting the rotation rate. Switching control for the current supplied to exciting coils is implemented by using an output signal from Hall elements for detecting the position of the rotor and the drive pulse. Correction of the pulse width of the drive pulse is implemented to ensure that the average voltage is maintained at a constant level even when the source voltage fluctuates so that stable rotation can be maintained over the entire rotation rate range even when the source voltage supplied to the brushless motor fluctuates and so that the fuse can be prevented from melting and the motor can be prevented from becoming damaged, which may otherwise be caused by a fluctuating source voltage.

Abstract: An object of preventing a reduction in the output efficiency of a motor in the high speed rotation range and reducing the noise of the motor in the low speed rotation range is to be achieved. Since, if a signal that corresponds to the rotation rate has a value equal to or smaller than a specific value, the timing with which a switch performs switching is retarded relative to the timing used when the signal corresponding to the rotation rate has a value larger than the specific value, once the operation shifts to the low speed rotation range, the switching timing is retarded to shift from the setting that gives priority to efficiency, to the setting for achieving noise reduction as long as the switching timing is set in advance so that an optimal output efficiency is achieved in the high speed rotation range.

Abstract: In order to prevent the performance of a motor from deteriorating due to a change in which the rotation rate of its rotor is to be increased suddenly, in a brushless motor in which a drive pulse whose pulse width is modulated in correspondence to a rotation rate setting signal input from the outside is formed and switching control is performed on the current supplied to the exciting coils by using output signals from the Hall elements that detect the position of the rotor and the drive pulse, the pulse width of the drive pulse is changed gradually and greatly until it reaches the pulse width that corresponds to the rotation rate setting signal when the upward change in the rotation rate of the rotor is to be large.

Abstract: The present invention offers a simple structure that facilitates the mounting of bearings, that maintains lubricating oil at a sufficient level in the bearing portions and that maintains an optimal distance between a rotor and a case housing for preventing freezing, for preventing reduction of the capacity and for preventing noise. Bearing stoppers provided between the bearings of the brushless motor and the bearing holders, which hold the upper end edge of each bearing, are secured at a projection formed at the internal circumferential surface of each bearing holder. A felt, which comes in contact with the lower portion of each bearing stopper and also comes in contact with the bearing at one side is provided, with holes communicating with the felt formed at the lower surface of the bearing stopper. In addition, the lower limit of the distance h between the lower end of the rotor and the upper end surface of the case housing is set at 1.5 mm.

Abstract: A brushless motor includes features that prevent jolting or shaking of a rotating shaft by urging the rotating shaft in one direction and have a simple construction and can heighten the mechanical strength of a portion holding the rotating shaft in order to lower noise. The brushless motor having a rotor having magnets and a rotating shaft, a stator for generating a rotating magnetic field with respect to the rotor, an exciting coil wound on the stator for receiving electrical power and for generating the magnetic field, and a holding plate including a magnetic member mounted in a position facing permanent magnets of the rotor. Accordingly, jolting or shaking of the rotating shaft can be prevented by urging the rotor and the rotating shaft toward the holding plate in order to attract the holding plate by the magnetic power of the magnets due to mounting the holding plate in a position facing the magnets of the rotor.

Abstract: A stepping motor control device for an automobile air-conditioning system has a key-off home-position setting unit of a stepping motor for driving an air-conditioning door in response to switching of a key switch of the automobile off. The key-off home-position setting unit, responsive to switch of the key switch off, drives the stepping motor so that the air-conditioning door comes to a full-close position or a full-open position, stores data indicative of the full-close or full-open positions, as a current position of the air-conditioning door in a memory, and thereby finishes a home-position setting of the stepping motor. The key-off home-position setting unit is supplied with power from a power source under control of a timer for a prescribed time within which a home-position setting can be finished.

Abstract: A control apparatus for controlling a rotational speed of a brushless direct current motor in accordance with a duty cycle of a pulse signal for controlling by the use of switching transistors exciting current flowing pulsewise through exciting coils of the motor. The apparatus has a detector for detecting the temperature of the transistors and the frequency of the pulse signal is determined in response to the detector so as not to overheat the transistors. Thus, smooth rotation can be obtained in a way that ensures that the transistors will not heat excessively.

Abstract: A rotor magnet of the type including a plurality of circumferentially arranged magnets of alternately opposite polarities, wherein each of the magnets has a magnetizing pattern such that the magnetic force is minimum at predetermined portions near opposite ends of the magnet and gradually increases from the predetermined portions toward the center of the magnet and also from the predetermined portions toward the opposite ends of the magnet. With this magnetizing pattern, the rotor magnet has a substantially sinusoidal waveform-like magnetic flux density distribution pattern when the motor is rotating. As a consequence, the magnetic polarity changes smoothly and the motor can, therefore, operate at a low operation noise.

Abstract: An apparatus for controlling a blower motor composed of a brushless motor is operative to control the blower motor, in the pulse width modulation (PWM) mode, with a number of pulses which are inversely proportional to a setting speed so as to reduce the motor operation noise and power consumption. An appropriate selection of the waveform to be supplied to the blower motor or the disturbance of the exciting timing of an exciting coil of the blower motor is effective to prevent the occurrence of a resonance phenomenon caused by vibrations produced by the blower motor.

Abstract: An aspirator fan is disclosed, which comprises a rotating shaft press-fitted in an impeller, a support member having an urging means and receiving one end of the rotating shaft for supporting the rotating shaft as a cantilever, and a shaft abutment member disposed in a casing and having a shaft abutment portion against which the opposite end of the rotating shaft is urged by the force of the resilient means. The aspirator fan is free of an alignment adjustment between the rotating shaft and bearings which is required in the casing of conventional aspirator fans. The shaft abutment member is structurally separated from the casing, so that even when the casing is deformed, a deformation of the casing has no effect on the rotation of the rotating shaft. The aspirator fan can, therefore, be operable with an improved reliability.

Abstract: A noise prevention apparatus for a blower unit using a brushless motor is disclosed in which, when a setting speed of rotation set by a rotational speed setting unit is judged as being equal to a speed of rotation corresponding to a natural frequency of the blower unit, a drive pulse which is to be provided to a switching unit for controlling the rotation of the blower is corrected by a drive pulse correction unit such that the setting speed of rotation is deviate from the speed of rotation corresponding to the natural frequency of the blower unit. With this arrangement, the brushless motor is driven at speeds other than the speed corresponding to the natural frequency of the blower. Consequently, a higher harmonic of the vibration of the motor is always kept out of coincidence with the natural frequency of the blower unit, so that a operation noise caused by resonance does not take place any more.

Abstract: An apparatus for controlling a brushless type blower motor of an automobile air conditioner includes a rotational speed setting unit for setting a rotational speed of the brushless motor, a drive unit for driving the brushless motor according to the speed of rotation set by the rotational speed setting unit, and a switching control unit for controlling the excitation timing of the brushless motor achieved by the drive unit. The driving unit includes a waveform storage unit for changing the waveform of a voltage to be impressed to the brushless motor. The waveform storage unit outputs a sine waveforms, a trapezoidal waveform or a square waveform according to the rotational speed set by the rotational speed setting unit.

Abstract: A blower control resistor device includes a plurality of resistors leading to resistor terminals, and a plurality of connecting terminals joined with the resistor terminals by thermal fuses. The joint portions between the resistor terminals and the connector terminals are concealed by a cover or the like so as to prevent an authorized modification of the resistor device. Preferably, one of the thermal fuses which is connected with a connector terminal near a power supply has a lower-melting point than other thermal fuses.

Abstract: A motor actuator for use in an automobile air-conditioner for actuating air-mix door, includes an electric circuit for controlling the rotational speed of a motor depending on various conditions such, for example, as a vehicle compartment temperature, and a mechanical limit switch for limiting or restricting the extent of angular movement of the air-mix door, or an electric circuit for the limitation of the angular movement of the air-mix door. According to a preferred embodiment, a built-in switching unit having a mechanical switch disposed in a first housing for producing control signals for various components for the air-conditioner, and a motor actuator having a motor and an electric circuit disposed in a second housing are detachably assembled together by a locking lug and a mating retainer recess.

Abstract: A motor actuator for an air conditioning system comprising a driving motor and an output shaft rotated by a driving force from the driving motor. At least one moveable contact is mounted on a contact mounting member rotatable together with the output shaft. Fixed contacts are mounted on a fixed circuit board. The movable contact is in sliding contact with the fixed contacts. A hysteresis imparting device is provided for imparting a hysteresis to the rotation of the contact mounting member with respect to the rotation of the output shaft. Further, the circuit board is interposed between an output gear on the output shaft and a switch disc rotatable together with the output gear. A switch device comprised of the movable contact and the fixed contacts is mounted between the circuit board and the output gear and/or between the circuit board and the switch disc.

Abstract: An intake air control device in an automotive air-conditioning apparatus includes an intake damper angularly movable selectively into a first position for circulating air in the passenger compartment of an automobile, a second position for introducing only ambient air into the passenger compartment, and a third position for introducing a smaller amount of ambient air into the passenger compartment than the amount of ambient air introduced by the intake damper in the second position. When air-conditioning control is commanded while only ambient air is being introduced, the intake damper is controlled to move to the third position for introducing a smaller amount of ambient air than the amount of ambient air introduced by the intake damper in the second position.

Abstract: A thermoswitch in which two fixed terminals are provided to a base disposed in a bottomed housing and a movable contact mechanism is provided between the two fixed terminals so that the movable contact is connected or disconnected by the displacement of a thermosensitive member such as bimetal, wherein the basal portions of the fixed terminals projecting from the base after solidifed with a first resin and a recess formed by the housing and base is filled and solidified with a second resin such that lead wires connected to the fixed terminals are embedded in the resin. According to this device, penetration of water coming down along the lead wires is positively prevented by the two resin layers.

Abstract: In a vane compressor, a rotational speed sensor for sensing the rotational speed of the rotor comprises a permanent magnet embedded in an end face of the rotor, a pin formed of a ferromagnetic material, rigidly fitted in a pump housing accommodating the rotor, with its one end disposed to encounter the permanent magnet, and a magnetically sensing element disposed opposite the other end face of the pin.