Valves and valve actuation – Electrically actuated valve – Rotary electric actuator
Reexamination Certificate
1999-12-10
2001-10-09
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Rotary electric actuator
C251S065000, C251S129090
Reexamination Certificate
active
06299129
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an actuator device with a valve for use in a device for controlling a flow rate of a fluid in a pipe wherein a toroidal core type actuator is used to directly open or close a valve based on an angle command value and, more particularly, to an actuator device with an engine throttle valve to be mounted on a vehicle.
2. Description of Related Art
Recently, a drive by wire system is widely used to improve automobile drivability and to accomplish counter-measures for exhaust gas. The drive by wire system, which does not use an accelerator cable, electrically detects by a sensor a depression amount of an accelerator pedal stepped by a driver and drives an engine throttle valve by a motor, thus operating the engine throttle valve completely independently of the operation of the accelerator pedal performed by the driver. As a result, the drive by wire system makes it possible to control engine output while always securing an appropriate air-fuel ratio for each situation, and therefore has been attracting attention and spreading as one of solutions to environmental problems.
In currently available drive by wire systems, however, throttle valves are usually driven by a combination of DC motors and decelerators as described in Japanese Laid-open Patent Application No. 5-240070 and U.S. Pat. No. 5,777,412. This is because driving a throttle valve requires a large torque ranging from about 30 to about 60 Ncm (230 Ncm in a freeze condition), so that the required torque cannot be provided by a motor alone unless torque is increased by the intermediary of a decelerator. Using the decelerator, however, adds to cost of a system and deteriorates reliability. Above all, the conventional drive by wire systems have a shortcoming in that highly accurate flow rate control cannot be achieved due to backlash of gears or the like.
There has been also known a direct drive system that uses a toroidal core type actuator having a rotary shaft that repetitively rotates. If an operating angle range of the rotary shaft is limited to about 0 degree to about 90 degrees, then the torque characteristic depends solely on an input current value and not depends on the angle. This characteristic is ideally suited for controlling rotational angles (the details will be described hereinafter). Making use of this characteristic, it is possible to control a flow rate with high accuracy by providing a pipe through which a fluid passes with a shaft orthogonalized with respect to an axis of the pipe, attaching a butterfly valve to the shaft, and by controlling the angle of the valve. This technology has been applied to a variety of attempts to directly drive an engine throttle valve. However, required torque is large for a size (e.g. a diameter of about 70 mm and a length of about 70 mm). Thus, no actuators that are adequate for practical use have been available.
However, high-performance magnet made of a rare earth element has been developed, leading to prospects of accomplishing rotor magnets in appropriate sizes that are capable of producing the required torque of about 30 to about 60 Ncm for driving throttle valves. Stators have been presenting shortcomings in that workability of toroidal winding process itself is poor, handling after the winding process is difficult, and accomplishing dimensional accuracy is difficult, either. Therefore, the stators have been disadvantageous in that it is difficult to install onto apparatuses with high accuracy, which has been a cause of higher cost.
SUMMARY OF THE INVENTION
The present invention has been made with a view toward solving the problem described above. It is an object thereof to provide an actuator device with a valve that overcomes shortcomings of an actuator for opening/closing a valve, which is comprised of a combination of a decelerator and a DC motor, and that is capable of adjusting a flow rate at low cost and with high accuracy. Preferably it is an object of the present invention to provide an on-vehicle actuator device with an engine throttle valve.
To this end, according to the present invention, there is provided a toroidal core type actuator comprising: a rotor composed of a permanent magnet rotatably supported on a rotary shaft thereof and has at least two magnetic poles of different polarity and a stator composed of a winding wrapped around a cylindrical core formed of a soft magnetic member disposed outside of said rotor via a minute air gap, wherein at least two phase separating members composed of a nonmagnetic material are arranged on said core equidistantly to each other, and coils are wound on winding regions provided between two adjacent phase separating members on said core at a substantially uniform density.
In a preferred form of the present invention, there is provided a toroidal core type actuator device with a valve for adjusting a flow rate in a pipe wherein a pipe through which a fluid is passed in provided with a rotary shaft to which a valve for adjusting a flow rate is fixed, an actuator and an angle sensor are arranged on an extended portion of said rotary shaft, and said valve is rotated with a torque corresponding to an output current value of an actuator driving circuit on the basis of an angle command value supplied to a control circuit so as to adjust a flow rate in the pipe; said actuator device with a valve comprising: a rotor composed of a permanent magnet rotatably supported on a rotary shaft thereof and has at least two magnetic poles of different polarity and a stator composed of a winding wrapped around a cylindrical core formed of a soft magnetic member disposed outside of said rotor via a minute air gap, wherein at least two phase separating members composed of a nonmagnetic material are arranged on said core equidistantly to each other, and coils are wound on winding regions provided between two adjacent phase separating members on said core at a substantially uniform density.
In a preferred form of the present invention, the fluid is air, and the actuator and the angle sensor are integrally installed in an engine throttle body.
In another preferred form of the present invention, the phase separating members are made of an insulative resin.
In a further preferred form, the phase separating members are at 10 degrees or less as central angle thereof the core circumference.
In yet another preferred form, an external diameter of a cylindrical core of an actuator is 70 mm or less, a length Y
1
(mm) of an air gap formed by a spacing between an inside diameter of the core and an outside diameter of a rotor magnet is set to be 1.5 mm≦Y
1
≦5 mm, a length Y
2
(mm) of an air gap formed by a spacing between an innermost diameter of the phase separating member and the outside diameter of the rotor magnet is set to be Y
1
−Y
2
≦0.5 mm, and the two sets of coils wrapped around the core is formed of three to four layers.
In still another preferred form, the phase separating members are integrally provided with insulating portions for electrically insulating the core and the winding.
In a further preferred form, at least one of the phase separating members is provided with a coil hooking terminal.
In a further preferred form, the cylindrical core (preferably, a surface thereof has been provided with insulation treatment) is made by forming a soft and thin magnetic strip of a uniform width into a roll shape.
In a further preferred form, the roll-shaped soft and thin magnetic strip has a tapered portion that gradually and continuously spreads wider from an innermost circumferential end of a rolling start portion.
In a further preferred form, the cylindrical core is formed by wrapping a pipe-shaped soft magnetic core member with a soft and thin magnetic strip having a uniform width into a roll shape, a surface thereof being provided with insulation treatment.
REFERENCES:
patent: 4976237 (1990-12-01), Bollinger
patent: 5785296 (1998-07-01), Peube et al.
patent: 6026343 (2001-03-01), Kato et al.
patent: 6206342 (2001-03-01), Beck
patent: 622403
Fujitani Sakae
Harada Naoyuki
Suzuki Yuzuru
Bonderer D. Austin
Howell & Haferkamp LC
Minebea Co. Ltd.
Shaver Kevin
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