1. Field of the Invention
The present invention relates to a rotary phase controller for varying rotary phase of a drive side and a follower side.
The present invention also relates to a valve timing controller for controlling timing of the internal combustion engine, by varying the rotary phase of the drive side and the follower side.
2. Description of the Related Art
A valve timing controller of an internal combustion engine varies a rotary phase between a drive rotor (which is connected to a crank shaft by way of a timing chain and the like) and a follower rotor (which is connected to a cam shaft side) through revolutionary operation relative to each other, to thereby control open-close timing of the internal combustion engine.
A rotary phase controller such as the valve timing controller described above generally uses fluid pressure. The rotary phase controller using the fluid pressure can assuredly control the rotary phase. The rotary phase controller using the fluid pressure, however, has complicated piping, which is responsible for its likeliness of becoming large in size. In addition, the rotary phase controller using the fluid pressure may have low responsiveness until sufficient fluid pressure is obtained.
Moreover, the following rotary phase controller is devised:
An electric motor gear incorporated between the drive rotor and the follower rotor is rotated so as to revolve the drive rotor relative to the follower rotor when so requested.
The above electric motor gear rotary phase controller can eliminate shortcomings which is caused when using the fluid pressure. The electric motor gear rotary phase gear, however, uses a slip ring and the like which constantly causes an impingement during rotation, and therefore, is low in durability.
Japanese Patent Unexamined Publication No. Heisei 3(1991)-050308 describes a rotary phase controller for varying rotary phase of the drive rotor and the follower rotor by means of a magnetic force (of an electromagnetic coil fixed to an irrotational member) and a spring member.
It is an object of the present invention to provide a rotary phase controller and a valve timing controller (for an internal combustion engine) featuring high durability as well as operation accuracy, by securing a drive rotor and a follower rotor at an arbitrary revolutionary position relative to each other.
According to a first aspect of the present invention, there is provided a rotary phase controller varying rotary phase of a drive rotor and a follower rotor through a relative rotary operation between the drive rotor which is rotatably driven and the follower rotor which receives a power from the drive rotor. The rotary phase controller comprises: a permanent magnet block), a yoke block, and an electromagnetic coil block. The permanent magnet block is disposed on one of the drive rotor""s side and the follower rotor""s side. The permanent magnet block has a constitution in which different magnetic pole surfaces of a permanent magnet are alternately arranged circumferentially. The yoke block is disposed as a whole on the other of the drive rotor""s side and the follower rotor""s side. The yoke block includes a plurality of yokes including a first yoke and a second yoke. Each of the plurality of the yokes includes: a first pole tooth ring formed with a plurality of first pole teeth which oppose the magnetic pole surfaces of the permanent magnet block, and a second pole tooth ring formed with a plurality of second pole teeth which oppose the magnetic pole surfaces of the permanent magnet block. The first pole teeth and the second pole teeth are alternately disposed circumferentially. The first yoke and the second yoke are assembled such that the first pole teeth of the first yoke are shifted by a predetermined pitch circumferentially from the second pole teeth of the second yoke. The electromagnetic coil block is fixed to an irrotational member. The electromagnetic coil block includes a plurality of electromagnetic coils including a first electromagnetic coil and a second electromagnetic coil corresponding respectively to the first yoke and the second yoke of the yoke block. Each of the first electromagnetic coil and the second electromagnetic coil has a magnetic input-output end opposing, by way of an air gap, the first pole tooth ring and the second pole tooth ring of the respective first yoke and second yoke. The yoke block and the permanent magnet block make a revolution relative to each other by varying at a predetermined pattern a magnetic field which is generated at the plurality of the electromagnetic coils.
According to a second aspect of the present invention, there is provided a valve timing controller of an internal combustion engine varying rotary phase of a crank shaft and a cam shaft through a relative rotary operation between a drive rotor which is driven by the crank shaft and a follower rotor which is one of the cam shaft and a member coupled to the cam shaft. The valve timing controller comprises: a permanent magnet block), a yoke block, and an electromagnetic coil block. The permanent magnet block is disposed on one of the drive rotor""s side and the follower rotor""s side. The permanent magnet block has a constitution in which different magnetic pole surfaces of a permanent magnet are alternately arranged circumferentially. The yoke block is disposed as a whole on the other of the drive rotor""s side and the follower rotor""s side. The yoke block includes a plurality of yokes including a first yoke and a second yoke. Each of the plurality of the yokes includes: a first pole tooth ring formed with a plurality of first pole teeth which oppose the magnetic pole surfaces of the permanent magnet block, and a second pole tooth ring formed with a plurality of second pole teeth which oppose the magnetic pole surfaces of the permanent magnet block. The first pole teeth and the second pole teeth are alternately disposed circumferentially. The first yoke and the second yoke are assembled such that the first pole teeth of the first yoke are shifted by a predetermined pitch circumferentially from the second pole teeth of the second yoke. The electromagnetic coil block is fixed to an irrotational member. The electromagnetic coil block includes a plurality of electromagnetic coils including a first electromagnetic coil and a second electromagnetic coil corresponding respectively to the first yoke and the second yoke of the yoke block. Each of the first electromagnetic coil and the second electromagnetic coil has a magnetic input-output end opposing, by way of an air gap, the first pole tooth ring and the second pole tooth ring of the respective first yoke and second yoke. The yoke block and the permanent magnet block make a revolution relative to each other by varying at a predetermined pattern a magnetic field which is generated at the plurality of the electromagnetic coils.