As an example of this type of the fluid jetting device, a local cleansing device for cleansing parts (anus for example) of the human body is well known. With this kind of the local cleansing device, upon jetting the cleansing water from a single fluid jetting spout toward a part of the human body, ordinarily, it is desirable that the water contact area of the jetted cleansing water is in some measure made to be a broad area.
In order to fulfill this sort of demand, a method of rotating a nozzle arm having a nozzle built therein in a circular path (nozzle arm rotation method) or a method of driving the nozzle itself within a nozzle arm having such nozzle built therein (nozzle rotation method) may be adopted. Incidentally, with the former method, since it is necessary to simultaneously control the nozzle arm in two axes on orthogonal coordinates, a drive motor or the like is required for the respective axes, and this resulted in the enlargement of the device. Meanwhile, with the latter method, since the drive target is only the nozzle, this is preferable in that the device can be miniaturized for such portion. This kind of nozzle rotation method has been variously proposed, for example, in JP 2000-8453 A, and may be classified broadly into a type that drives the nozzle with electrical power and a type that drives the nozzle with cleansing water pressure. The latter is superior to the former in terms of energy conservation.
FIG. 1 is an explanatory diagram for explaining the structure conventionally adopted so as to rotatably drive the nozzle with cleansing water pressure, wherein FIG. 1(a) is an explanatory diagram illustrating a schematic cross section of the nozzle arm, and FIG. 1(b) is an explanatory diagram illustrating the schematic cross section of line A—A thereof.
As shown in FIG. 1, a truncated cone-shaped nozzle is rotatably built in the chamber of the nozzle arm, and a plurality of curved grooves is formed around the peripheral wall of the nozzle. This nozzle, at the tip side thereof, is sealed to the inner face of the chamber with a seal member. When cleansing water is supplied to this kind of nozzle, the nozzle rotates with the pressure of the cleansing water upon such cleansing water passing through the grooves between the inner face of the chamber and the peripheral wall of the nozzle. Thus, the nozzle jets cleansing water from the jetting spout at the nozzle tip so as to broaden the water contact area.
Nevertheless, with the foregoing conventional structure, since a seal member lies between the nozzle tip and inner face of the chamber, the nozzle is subject to a relatively large rotational resistance from the seal member during the rotation thereof.
Rotational speed of the nozzle affects the broadening of the cleansing water from the jetting spout, and a certain degree of rotational speed is required in order to broaden the water contact area. As a result, the water pressure upon supplying cleansing water must be increased in order to elicit and maintain the rotation of the nozzle, and problems such as the enlargement of the actuator of pumps or the like and increased operating costs would arise.
These problems are not typical to a cleansing water jetting device as represented with a local cleansing device, and, even with a fluid jetting device employed for other purposes, similar problems occur as a result of the structure of rotating the nozzle with fluid pressure.
The present invention was devised in view of the foregoing problems, and an object thereof is to seek, upon adopting the structure of rotating the nozzle with fluid pressure, the miniaturization of the actuator of a pump or the like for supplying fluid to the chamber, and the reduction of operating costs.