Dog clutch mechanism

A dog clutch mechanism for switching drive power in a four-wheel-drive vehicle having front and rear wheels, comprising:

• a case;
• first and second rotatable shafts rotatably supported coaxially in said case for transmitting a relative torque between the front and rear wheels;
• dog clutch means comprising a dog piece having first dog teeth and fixedly mounted on said first rotatable shaft and a hub having second dog teeth capable of axially meshing with said first dog teeth and axially slidably mounted on said second rotatable shaft, said dog clutch means being selectively engageable for transmitting the relative torque between said first and second rotatable shafts;
• said first and second dog teeth having respective meshing tapered surfaces for producing thrust forces acting on said hub and tending to move said hub in a direction away from said dog piece when the vehicle is braked while a relative forward torque is being transmitted between said first and second rotatable shafts through said dog clutch means, the tapered surfaces of each dog tooth being of opposite inclination with different angles of taper, one of said tapered surfaces being engaged during transmission of driving torque through said dog clutch means while the other of the tapered surfaces is engaged during braking, said one tapered surface having a smaller taper than said other tapered surface so that greater thrust force will be applied during braking to disengage the dog clutch means,
• said hub comprising a tubular portion axially slidably mounted on said second rotatable shaft;
• shift means for moving said first and second dog teeth into and out of mesh with each other, said shift means comprising a tubular engaging member slidably disposed around said tubular portion of said hub, balls disposed in holes defined in said tubular portion and extending towards said second rotatable shaft, said balls being movable by said tubular engaging member into an annular groove defined in said second rotatable shaft when said first and second dog teeth mesh with each other.

A dog clutch mechanism for switching drive power in a four-wheel-drive vehicle having front and rear wheels, comprising:

• a case;
• first and second rotatable shafts rotatably supported coaxially in said case for transmitting a relative torque between the front and rear wheels;
• dog clutch means comprising a dog piece having first dog teeth and fixedly mounted on said first rotatable shaft and a hub having second dog teeth capable of axially meshing with said first dog teeth and axially slidably mounted on said second rotatable shaft, said dog clutch means being selectively engageable for transmitting the relative torque between said first and second rotatable shafts;
• said first and second dog teeth having respective meshing tapered surfaces for producing thrust forces acting on said hub and tending to move said hub in a direction away from said dog piece when the vehicle is braked while a relative forward torque is being transmitted between said first and second rotatable shafts through said dog clutch means, the tapered surfaces of each dog tooth being of opposite inclination with different angles of taper, one of said tapered surfaces being engaged during transmission of driving torque through said dog clutch means while the other of the tapered surfaces is engaged during braking, said one tapered surface having a smaller taper than said other tapered surface so that greater thrust force will be applied during braking to disengage the dog clutch means,
• an electromagnetic actuator having a movable member for actuating said dog clutch means, and a power transmitting mechanism disposed adjacent to said first rotatable shaft for receiving the transmitted torque;
• and
• said case having a first chamber housing said dog clutch means and defined by at least on oil seal member, a second chamber housing said electromagnetic actuator and defined and closed by at least a seal member, a third chamber housing said power transmitting mechanism and defined by at least an oil seal member, and an air passage means defined by at least said oil seal members and said seal member and communicating with said second chamber through a communication hole for venting said second chamber to atmosphere.