Valves and valve actuation – Permanent or constantly energized magnet actuator
Reexamination Certificate
2002-11-04
2004-03-09
Mar, Michael (Department: 3754)
Valves and valve actuation
Permanent or constantly energized magnet actuator
C251S230000, C137S530000, C604S009000
Reexamination Certificate
active
06702249
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure-variable valve device and, more specifically, to a pressure-variable valve device suitable for use as a shunt valve embedded in the human body to adjust the pressure of the spinal fluid or the like, and to a set-pressure adjusting device therefor.
2. Description of the Prior Art
Japanese Patent Application Laid-Open No. 60-40063 discloses a technique for treatment for hydrocephalus or the like in which the pressure of the spinal fluid or the like is adjusted by providing in the flow passage of the spinal fluid or the like a shunt valve (branch valve) device in which the forward ends of arm portions on both sides of a fork-like plate spring are locked, and the forward end of a central arm portion is held in contact with a ball serving as a valve, and in which the base end portion of the fork is engaged with a spiral cam surface formed on a rotating member rotatable around a central axis, and the engagement base portion of the spring is moved in the axial direction of the rotating member in accordance with the rotation of the cam surface as a result of the rotation of the rotating member to vary the deflection amount of the spring, thereby varying the pressure applied to the ball by the spring. In this shunt valve device, a ratchet having claws on the peripheral surface is formed integrally with the rotating member, and two engagement members are arranged opposite to the claws of the ratchet, each engagement member being rotatable around a fulcrum situated in the intermediate portion with respect to the longitudinal direction and having at both ends engagement pawls which can be engaged with the claws of the ratchet. Further, magnets are mounted to the engagement members such that the adjacent end portions of the two engagement members are of the same polarity. When a magnetic field is applied in one direction from outside, the two engagement members rotate in the same direction around their respective rotation axes to cause the ratchet to rotate in a direction corresponding to the direction of the above rotation. Next, a reverse magnetic field is applied to restore the two engagement members to the original rotating positions. By repeating these operations, the rotating position of the rotating member is adjusted (
FIGS. 10
a
through
10
d
and
FIG. 11
of the above-mentioned publication).
However, in this set-pressure-variable shunt valve or pressure-variable valve device, there is the danger that an undesired change in the set pressure occurs in an environment in which the direction of the external magnetic field applied to the entire shunt valve varies. That is, when a patient suffering from hydrocephalus or the like, under whose scalp the shunt valve is embedded, undergoes inspection and diagnosis of the head by an MRI (magnetic resonance imaging) apparatus, the patient, in a typical case, moves the head portion to be inspected and diagnosed in various directions in the MRI apparatus with respect to the strong and spatially uniform main magnetic field applied in the Z-direction of the apparatus, with the result that there is applied to the shunt valve portion a magnetic field whose direction varies in the same sequence as when the rotating position of the rotating member of the shunt valve is adjusted, thereby causing an undesired deviation in the set pressure.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problem in the prior art. It is accordingly an object of the present invention to provide a pressure-variable valve device in which there is little danger of the set pressure being deviated even in the main magnetic field of an MRI apparatus, and a set-pressure adjusting device for such a valve device.
To achieve the above object, there is provided, in accordance with the present invention, a pressure-variable valve device which is adapted to be embedded in the human body and which is capable of changing a difference in pressure between an inlet-side duct and an outlet-side duct, the valve device comprising a rotating member capable of rotating around a central axis inside a valve-device main body to vary a set pressure of a valve, and a rotation control mechanism for controlling the rotation of the rotating member, wherein the rotation control mechanism includes at least one permanent magnet structure supported by the valve-device main body so as to be capable of making a linear reciprocal translation in the valve-device main body, and a displacement transmission mechanism for rotating the rotating member in a direction corresponding to the direction of the translation of the permanent magnet structure.
In the pressure-variable valve device of the present invention, there are provided “at least one permanent magnet structure supported by the valve-device main body so as to be capable of making a linear reciprocal translation in the valve-device main body, and a displacement transmission mechanism for rotating the rotating member in a direction corresponding to the direction of the translation of the permanent magnet structure”, so that, by applying to a portion in the vicinity of the permanent magnet structure a magnetic field which causes the permanent magnet structure to make a translation movement in a direction corresponding to the direction of rotation of the rotating member by the displacement transmission mechanism (When there are a plurality of permanent magnet structures, the direction of translation of each permanent magnet structure is made the same as the direction of the torque applied to the rotating member), it is possible to rotate the rotating member in a desired direction. Further, in the pressure-variable valve device of the present invention, the rotating member is “capable of rotating around a central axis inside a valve-device main body to vary a set pressure of a valve”, so that, by rotating the rotating member, it is possible to change the set pressure of the valve device, that is, the difference in pressure between the inlet-side duct and the outlet-side duct.
Further, in the pressure-variable valve device of the present invention, the permanent magnet structure is “supported by the valve-device main body so as to be capable of making a linear reciprocal translation in the valve-device main body”, so that, when the pair of magnetic poles (N, S) of the permanent magnet structure are simultaneously exposed to a magnetic field of the same direction and of actually the same strength like the main magnetic field in the Z-direction of an MRI apparatus, the forces causing the permanent magnet structure to make a translation are balanced, the forces applied to the magnetic poles being of the same magnitude and opposite directions. Thus, the permanent magnet structure is not actually caused to make a translation movement, and no torque is imparted to the rotating member, so that there is no danger of the rotating member being caused to rotate. That is, even when a person in whose body a pressure-variable valve device of the present invention is embedded is placed in the strong main magnetic field of an MRI apparatus for inspection or diagnosis, there is little danger of the rotating member of the valve device making an unexpected rotation and little danger of the set pressure of the valve device being changed.
In the valve device of the present invention, as long as it is possible to change the difference in pressure between the inlet-side duct and the outlet-side duct, the valve of the valve device may be of the type which normally keeps the flow passage closed and allows the inlet-side duct to communicate with the outlet-side duct when the set pressure is reached (normally-closed type), or of the type which normally keeps the valve flow passage open and in which the size of the aperture of the valve flow passage determines the difference in pressure between the inlet-side duct and the outlet-side duct (normally-open type). In the case of the former type, the set pressure is changed or adjusted by changing or adjusting
Adams & Wilks
Keasel Eric
Mar Michael
Seiko Instruments Inc.
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