A power transmission device includes an armature that is shaped into a circular ring form. The armature is configured to be coupled with a rotor by an electromagnetic attractive force of an electromagnet at a time of energizing the electromagnet and is configured to be decoupled from the rotor at a time of deenergizing the electromagnet. The armature has an armature-side friction surface that is configured to contact a rotor-side friction surface of the rotor at the time of energizing the electromagnet. The armature-side friction surface has a plurality of grooves, each of which extends from a radially inner end portion of the armature-side friction surface to a location that is on a radially inner side of a radially outer end portion of the armature-side friction surface.

This Application pertains to an electromagnetic dog clutch, including a movable gear sleeve and a fixed toothed sleeve that are engaged to transmit power. The movable gear sleeve is provided with contrate transmission teeth or tooth spaces, and the fixed toothed sleeve is correspondingly provided with contrate tooth spaces or transmission teeth. The transmission teeth have a uniform thickness in a direction of tooth length, tooth spaces that engage with the transmission teeth have a sector-shape in a direction of tooth space length, and the width of two sides of the tooth spaces gradually increases outwardly along the radial direction of the fixed toothed sleeve and gradually decreases inwardly along the radial direction of the fixed toothed sleeve. By employing the engagement of transmission teeth of uniform thickness and sector-shaped tooth spaces, the transmission teeth can more easily engage with the tooth spaces, and more easily realize surface contact.

The present invention discloses a spring clutch comprising a coil assembly, a rotor assembly and a pulley assembly. The coil assembly comprises a coil housing, an encapsulated coil and a shell, the encapsulated coil is in the coil housing. The rotor assembly comprises a shaft, a rotor and a sleeve, the sleeve is on the shaft, the shaft is in the rotor, the shaft is in the coil housing. The pulley assembly comprises an armature, leaf springs, a brake plate and a pulley, one side of the leaf spring is pressed with armature and the another side is pressed with pulley, the brake plate is outside of the armature and covered some area of the armature, the pulley is on the sleeve. The brake plate has magnet pieces inside. A spring clutch in accordance with the present invention the brake plate has magnet pieces inside to make the armature has magnetic force to catch up with the brake plate to enable the clutch has strong friction force to reduce the stop time.

An improved electromagnetic clutch for use in a riding lawnmower or similar vehicle is provided. The clutch comprises a coil assembly, a rotor assembly and a pulley assembly. The coil assembly comprises a shell, an encapsulated coil and a coil ring, the coil ring is pressed in the encapsulated coil, the encapsulated coil is inside of the shell, the extended piece of the shell has magnets and brake pieces. The rotor assembly comprises a rotor and a shaft, the shaft pressed in the rotor and is on the coil ring. The pulley assembly comprises a pulley, an armature and leaf springs, one side of the leaf spring is pressed on armature and the another side is pressed on pulley, the pulley is on the shaft, the location of the armature is between brake pieces and rotor. The encapsulated coil has thermal fuse inside and the thermal fuse electrical connected with coil wires, the electricity will be cut off when the temperature of encapsulated coil higher than the melting point of the thermal fuse caused by fitting incorrect or slipping happened during clutch working to protect lawnmower parts or avoid fire accident.

An electromagnetic clutch mechanism includes: a driving-side rotatable body; a driven-side rotatable body; an electromagnet; a flat spring; and an elastic member that alleviates a collision impact generated between the driven-side rotatable body and the driving-side rotatable body. The driven-side rotatable body includes a recess recessed in an A direction, which is opposite to a direction that is directed from the driven-side rotatable body toward the elastic member in an axial direction. The recess functions as an urging portion that exerts an urging force to the elastic member through contact of the recess against the elastic member at the time of energizing the electromagnet. The elastic member includes an urging-force receiving portion, and the urging-force receiving portion receives the urging force from the recess through contact of the urging-force receiving portion to the recess at the time of energizing the electromagnet.

An electromagnetic clutch includes an armature to be attracted to a rotor, an armature hub formed on one end portion of a rotating shaft, and a leaf spring which connects the armature to the armature hub and biases the armature away from the rotor. The leaf spring includes a base fixed to the armature hub, a stopper connected to the base, and a connecting piece surrounding the stopper by projecting outside from the base, and fixed to the armature. A through hole into which a rivet for fixing the base to the armature hub is inserted is formed in the base. A low-strength portion having strength lower than that in the periphery of the through hole is formed in a boundary portion between the base and a connecting portion.

An electromagnetic clutch includes a field core including a coil storage groove, and a rotor including a core storage groove. The coil storage groove is formed by an inner cylindrical portion, an outer cylindrical portion, and a bottom portion. The bottom portion of the field core wholly projects to the outside of the core storage groove. The outer peripheral surface of the inner cylindrical portion and the inner peripheral surface of the outer cylindrical portion include a first transition surface and a second transition surface, respectively, on the bottom portion side. Each of the first transition surface and the second transition surface includes a tilting surface that gradually narrows the groove width of the coil storage groove along with an increase in a distance from the side of the opening of the coil storage groove.

The present disclosure relates to an electromagnetic clutch including a shifting sleeve which has a first toothing, is arranged in a rotationally fixed manner on a first shaft and can be displaced linearly along the first shaft between an engaged and a disengaged state, a first clutch body, which has a second toothing and which is aligned coaxially to the first shaft, the first and/or the second toothing having undercuts in the direction of the engaged state, which are configured such that a torque transmission between the first shaft and the first clutch body generates a force on the shifting sleeve in the direction of the engaged state. The present disclosure also relates to a method of closing and opening an electromagnetic clutch.

An electromagnetic clutch includes: a driving-side rotatable body that is rotated about an axis of a rotatable shaft of a drive-subject device; and a driven-side rotatable body that is placed on one side of the driving-side rotatable body in an axial direction. The electromagnetic clutch includes a flat spring that is formed to be rotatable integrally with the rotatable shaft of the drive-subject device and is joined to the driven-side rotatable body. The electromagnetic clutch includes a blocking member that is installed to the flat spring. A primary through-hole is formed in the driven-side rotatable body. A secondary through-hole is formed in the flat spring. Switching between coupling and decoupling between driving-side rotatable body and the driven-side rotatable body is made through elastic deformation of the flat spring. The blocking member closes the secondary through-hole.

This application pertains to an electromagnetic dog clutch, including a movable gear sleeve and a fixed toothed sleeve that are engaged to transmit power. The movable gear sleeve is provided with contrate transmission teeth or tooth spaces, and the fixed toothed sleeve is correspondingly provided with contrate tooth spaces or transmission teeth. The transmission teeth have a uniform thickness in a direction of tooth length, tooth spaces that engage with the transmission teeth have a sector-shape in a direction of tooth space length, and the width of two sides of the tooth spaces gradually increases outwardly along the radial direction of the fixed toothed sleeve and gradually decreases inwardly along the radial direction of the fixed toothed sleeve. By employing the engagement of transmission teeth of uniform thickness and sector-shaped tooth spaces, the transmission teeth can more easily engage with the tooth spaces, and more easily realize surface contact.