BACKGROUND ART In the past, ultrasonic cleaning devices have been widely utilized to remove stains from an object to be cleaned with a cleaning medium such as water or a solvent in the presence of ultrasonic vibrations.

For example, Japanese Patent Early Publication [kokai] No. 10-328472 discloses a batch-type ultrasonic cleaning device 1M, as shown in FIG. 10. In the use of this cleaning device, an object T to be cleaned is immersed in a vessel 10M filled with a cleaning medium 2M, and then an ultrasonic wave is applied to the cleaning medium by use of a vibrator 30M. Since the outer surface of the object immersed in the vessel 10M can be cleaned at a time, a high cleaning efficiency is achieved. However, it is needed that the vessel has a sufficient internal volume, in which the object can be put. This leads to an increase in size of the cleaning device. In addition, when the cleaning medium in the vessel 10M is contaminated, the removed stains may adhere to the object again. Therefore, there is an inconvenience that a contamination degree of the cleaning medium must be always checked.

On the other hand, as shown in FIGS. 11A and 11B, Japanese Patent Early Publication [kokai] No. 6-218337 discloses a nozzle shower-type ultrasonic cleaning device 1N having the capability of spraying a liquid 2N such as water on an object T to be cleaned, while irradiating an ultrasonic wave from a horn 30N to the object T. In this case, stains removed from the object by the ultrasonic wave can be washed away by the sprayed water. Therefore, this device is effective to remove stains from a large-scaled object such as walls of

buildings or lavatory bowls. In addition, when a pool of the liquid 2N is formed between a top end of the horn 30N and the object during the cleaning operation, the stains can be more effectively washed away from the object by an inflow of fresh water sprayed from the horn into the pool and an outflow of waste water including the removed stains from the pool. However, to stably obtain such a pool of the liquid 2N, it is needed that the tip of the horn has a unique shape, as shown in FIG. 11A. As a result, there is a fear that the pool of the liquid 2N can not be stably obtained, depending on shape of the object.

SUMMARY OF THE INVENTION Therefore, a primary concern of the present invention is to provide an ultrasonic cleaning device having the capability of safely and efficiently cleaning an object to be cleaned (preferably parts of a living body) with a liquid as a cleaning medium, to which an ultrasonic wave is being applied, while minimizing transmission loss of the ultrasonic wave.

That is, the ultrasonic cleaning device of the present invention comprises: a housing having a liquid outlet, and a chamber communicated with the liquid outlet; a supply unit for feeding a liquid as a cleaning medium to the chamber; an ultrasonic transmission member having an ultrasonic radiation surface at its one end; an ultrasonic transducer attached to an opposite end portion of the transmission member to apply an ultrasonic wave to the liquid in the chamber through the ultrasonic radiation surface of the transmission member; and a shield member for preventing a propagation of the ultrasonic wave from the transmission member to the housing, which is supported between an inner surface of the housing and the transmission member.

According to the present invention, since a pool of the liquid as the cleaning medium is always obtained in the chamber communicated with the liquid outlet of the housing during the cleaning operation, it is possible to stably provide a high cleaning effect, regardless of shape of the object, by

contact of the pool with the object through the liquid outlet. At this time, stains removed from the object can be efficiently washed away by the liquid successively supplied into the chamber by the supply unit. In addition, since the ultrasonic radiation surface of the ultrasonic transmission member (i. e., horn) do not contact the object during the cleaning operation, it is possible to safely clean parts of a living body as the object to be cleaned with the liquid, to which the ultrasonic wave is being applied.

By the way, in the case of accommodating the transmission member in the housing, when a side of the transmission member near the ultrasonic radiation surface is directly supported by the housing, there is a problem that a transmission loss is caused by a propagation of the ultrasonic wave from the transmission member to the housing. In particular, this problem becomes serious in the case of using the ultrasonic wave having a relatively low frequency of, e. g. , 20 to 60 kHz, which is better suited for removing tough stains. That is, when the transmission member is supported by the housing at a location corresponding to the position of an antinode (i. e. , maximum amplitude) of the ultrasonic vibration, heat is generated at a portion of the housing for supporting the transmission member by the ultrasonic vibration.

This means that a part of the ultrasonic wave energy to be applied to the liquid in the chamber is lost as heat. In the present invention, since the shield member is disposed between the housing and the transmission member, it is possible to efficiently apply the ultrasonic wave to the liquid in the chamber, while minimizing the transmission loss of the ultrasonic wave.

Specifically, as a preferred embodiment of the present invention, the shield member is an elastic member supported in a water tight manner between the inner surface of the housing and a side of the transmission member near the radiation surface, and the chamber is provided by a space surrounded by the inner surface of the housing, the ultrasonic radiation surface of the transmission member, and the elastic member. In addition, it is preferred that the transmission member has a penetration channel communicated with the

ultrasonic radiation surface, and the supply unit feeds the liquid into the chamber through the penetration channel. In this case, since it is not needed to separately form a liquid supply channel adjacent to the transmission member in the housing, it is effective to downsize the ultrasonic cleaning device.

Alternatively, as another preferred embodiment of the present invention, the shield member is formed with a bottom wall connected to the ultrasonic radiation surface of the transmission member and a side wall projecting from the circumference of the bottom wall to provide an opening at its top, and the chamber is provided by an internal space of the shield member, and the opening works as the liquid outlet. In addition, it is preferred to dispose an elastic member between the side wall of the shield member and the inner surface of the housing.

Moreover, it is preferred that the transmission member has a penetration channel communicated with the ultrasonic radiation surface, and the supply unit feeds the liquid into the internal space of the shield member through the penetration channel and an aperture formed in the bottom wall of the shield member. In this case, since it is not needed to separately form a liquid supply channel adjacent to the transmission member in the housing, it is effective to downsize the ultrasonic cleaning device.

Further characteristics of the present invention and effects brought thereby will be clearly understood from the best mode for carrying out the invention described below.

BREIF EXPLANATION OF THE DRAWINGS FIG. 1A is a schematic cross-sectional view of an ultrasonic cleaning device according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view of the cleaning device taken along the line P-P of FIG. 1A ; FIG. 2 is a schematic diagram illustrating a shield member of the cleaning device; FIG. 3 is a schematic cross-sectional view of an ultrasonic cleaning device

according to a modification of the first embodiment; FIG. 4 is a partially cross-sectional view of an ultrasonic cleaning device according to a further modification of the first embodiment; FIG. 5 is a partially cross-sectional view of an ultrasonic cleaning device according to another modification of the first embodiment; FIG. 6A is a schematic cross-sectional view of an ultrasonic cleaning device according to a second embodiment of the present invention, and FIG. 6B is a perspective view of a shield member of the cleaning device ; FIG. 7 is a schematic cross-sectional view of an ultrasonic cleaning device according to a modification of the second embodiment; FIG. 8 is a partially cross-sectional view of an ultrasonic cleaning device according to a further modification of the second embodiment; FIG. 9 is a partially cross-sectional view of an ultrasonic cleaning device according to another modification of the second embodiment; FIG. 10 is a schematic cross-sectional view of a conventional ultrasonic cleaning device of batch-type; and FIGS. 11A and 11B are perspective and cross-sectional views of a conventional ultrasonic cleaning device of nozzle shower-type.

BEST MODE FOR CARRYING OUT THE INVENTION An ultrasonic cleaning device of the present invention is explained in detail according to preferred embodiments, referring to the attached drawings.

<First Embodiment As shown in FIG. 1, the ultrasonic cleaning device 1 of this embodiment comprises a housing 10 having a liquid outlet 12 and a chamber 11 communicated with the liquid outlet, liquid supply unit 20 for feeding a liquid 2 as a cleaning medium to the chamber 11, ultrasonic transmission member 30 having an ultrasonic incident surface 31 at its one end and an ultrasonic radiation surface 33 at the opposite end, ultrasonic transducer 40 connected attached to the ultrasonic incident surface of the transmission member to apply an ultrasonic wave to the liquid in the chamber through the ultrasonic

radiation surface, drive circuit 42 for driving the ultrasonic transducer, and an O-ring 50 supported between an inner surface of the housing 10 and the transmission member 30.

The housing 10 is made of an insulating material such as synthetic resins, and configured in a tapered nozzle shape such that a cross section perpendicular to an axial direction of the housing gradually decreases toward the liquid outlet 12. In addition, since the housing 10 has a handle portion 13 formed in an elongate shape that is east to grip, the user can carry the liquid outlet accurately to a desired portion of an object to be cleaned.

As the ultrasonic transducer 40, for example, a conventional piezoelectric vibrator can be used, which is composed of a ceramic material such as such as lead titanate or crystalline quartz, and activated in a thickness-vibration mode by the drive circuit 42. The drive circuit can be formed by mounting electronic parts for an oscillating circuit on a substrate. The drive circuit 42 is powered by use of a rechargeable battery (not shown) detachably attached to the housing or a commercial power source. In the cleaning device of the present invention, it is preferred to use the ultrasonic wave having a relatively low vibration frequency of several ten kHz, which is better suited for removing tough stains from the object to be cleaned. For example, when the frequency of the ultrasonic wave used is in a range of 20 to 60 kHz, there is an advantage that the cleaning effect is further improved by a cavitation pressure in the liquid. In addition, the vibration amplitude of the ultrasonic wave becomes maximum at the ultrasonic radiation surface 33 of the transmission member 30. For example, in the case of using the ultrasonic wave of 40 kHz, the maximum vibration amplitude is approximately 20 um.

The ultrasonic transmission member 30 is made of a metal material, for example, a light alloy such as aluminum alloys or a light metal such as aluminum, and has a circular truncated cone shape composed of a base used as the ultrasonic incident surface 31, cap having a smaller area than the base and used as the ultrasonic radiation surface 33, a flat side surface 32 projected

from the circumference of the base, and a curved side surface 34 extending between the flat side surface 32 and the ultrasonic radiation surface 33. The flat side surface 32 of the transmission member 30 is supported by a projection 15 formed on the inner surface of the housing 10. A position of the projection 15 is determined to substantially correspond to an node (i. e., minimum amplitude) of the ultrasonic vibration propagated in the axial direction of the transmission member. Therefore, the transmission loss of the ultrasonic wave through the projection 15 is extremely small.

On the other hand, at the curved side surface 34 near the ultrasonic radiation surface 33, the transmission member 30 is supported in a watertight manner by the O-ring 50 disposed on the inner surface of the housing 10.

This O-ring works as a shield member for preventing a propagation of the ultrasonic wave from the transmission member 30 to the housing 10. In this embodiment, the chamber 11 is provided by a space surrounded by the inner surface of the housing 10, the ultrasonic radiation surface 33 of the transmission member 30 and the O-ring 50 of the shield member. By the presence of the O-ring 50, it is possible to minimize the transmission loss of the ultrasonic wave, and simultaneously prevent leakage of the liquid 2 from the chamber 11 into the interior space of the housing 10 for accommodating the ultrasonic transducer 40 and the drive circuit 42. In addition, it is preferred that the inner surface of the housing 10 facing the chamber 11 is coated with an ultrasonic reflection material, or an ultrasonic reflector is disposed on the inner surface of the housing.

The O-ring 50 of the shield member can be made of a rubber material.

Shape and size of the shield member are not specifically restricted. For example, as shown in FIG. 2, it is preferred that a difference between an outer <BR> <BR> diameter LI of the O-ring 50 and a diameter L2 of the cap (i. e. , the ultrasonic radiation surface 33) of the transmission member 30 is 2 mm or less.

The liquid supply unit 20 comprises a tank 22 for storing the liquid therein, a pump 24 activated by the drive circuit 42, and a pipe 26 used as a

flow channel for the liquid 2 extending from the pump to the chamber 11. The liquid 2 supplied into the chamber 11 can be flow outside through the liquid outlet 12. In FIG. 1B, the numeral 17 designates a communication port formed in the housing 10 to feed the liquid 2 from the pipe 26 into the chamber 11. If necessary, the liquid supply unit 20 may have a switch valve for connecting the pipe 26 to a faucet of water or an outside tank for the cleaning medium.

In this cleaning device, the liquid 2 such as water or a mixture of water and a cleaning agent is successively supplied into the chamber 11 by the liquid supply unit 20, to thereby obtain a pool of the liquid as the cleaning medium in the chamber. On the other hand, the ultrasonic wave provided from the ultrasonic transducer 40 is applied to the liquid 2 in the chamber through the ultrasonic radiation surface 33 of the transmission member 30. Therefore, it is possible to effectively clean the object by allowing the liquid 2, to which the ultrasonic wave is being applied, to contact the object through the liquid outlet 12. In addition, as described before, since the housing 10 has the tapered nozzle shape, it is possible to provide a focused liquid flow of the ultrasonic-applied cleaning medium from the liquid outlet, as shown by the arrows S in FIG. 1A.

Additionally, in the case of cleaning parts of a living body as the object to be cleaned, when the ultrasonic transmission member contacts the parts of the living body during the cleaning operation, there is a fear that heat generation or pain occurs at the cleaned parts. In the present invention, since the ultrasonic radiation surface 33 of the transmission member 30 is positioned in the housing 10, it is possible to safely perform the cleaning operation by the liquid, to which the ultrasonic wave is being applied, by preventing that the ultrasonic radiation surface accidentally contacts the parts of the living body.

As a modification of this embodiment, a liquid supply unit 20 shown in FIG. 3 may be used, which is characterized by using a penetration channel 36 formed in the transmission member 30 to extend in the axial direction between

the ultrasonic incident surface 31 and the ultrasonic radiation surface 33 in place of the pipe 26. Therefore, the liquid 2 can be supplied into the chamber 11 through the penetration channel 36 by the pump 24, as shown by the arrows in FIG. 3. In this modification, since no space for accommodating the pipe 26 in the housing 10 is needed, it is suitable to downsize the ultrasonic cleaning device. In addition, to further facilitate downsizing of the ultrasonic cleaning device, it is preferred to use a Langevin-type transducer as the ultrasonic transducer 40.

As another modification of this embodiment, as shown in FIG. 4, it is preferred that a groove 37 is formed in a side surface of the transmission member 30 such that the O-ring 50 can fit in the groove. Alternatively, as shown in FIG. 5, it is preferred that grooves (37, 16) are respectively formed in both of the side surface of the transmission member 30 and the inner surface of the housing 10 such that the O-ring 50 can fit in those grooves In these cases, it is possible to stably support the transmission member 30 in the housing 10, and further improve the sealing reliability. Depth (dl, d2) of the respective groove is not specifically restricted. For example, the depth is 1 mm or less. In addition, the O-ring 50 may be supported in a clearance between a pair of walls projecting on the inner surface of the housing.

<Second Embodiment An ultrasonic cleaning device 1 of this embodiment is substantially the same as the first embodiment except for the following features. Therefore, the same components in the ultrasonic cleaning device shown in FIG. 6A are assigned the same numerals used in the first embodiment, and duplicate explanations are omitted.

In place of the O-ring 50 used as the shield member in the first embodiment, the shield member 5 of the ultrasonic cleaning device 1 of this embodiment is configured in a hollow, circular truncated cone shape shown in FIG. 6B, which comprises a bottom wall 52 connected to the ultrasonic radiation surface 33 of the transmission member 30 and a tapered side wall 54

projected from the circumference of the bottom wall to provide an opening 56 at its top. For example, the shield member 5 can be made of a rubber material.

An angle between the side wall 54 and the bottom wall 52 of the shield member is determined such that the side wall contacts the inner surface of the housing 10 in a face-to-face manner. Therefore, an internal space of the shield member 5 provides the chamber 11. The liquid 2 is supplied as the cleaning medium into the chamber 11 by the liquid supply unit 20 through a communication port 53 formed in the bottom wall 52 of the shield member.

The liquid 2 in the chamber 11 flows out from the opening 56 of the shield member 5, which is positioned in the vicinity of the liquid outlet 12 of the housing 10.

In this case, since the ultrasonic wave provided from the ultrasonic radiation surface 33 of the transmission member 30 mainly propagates in the liquid 2 in the chamber 11, a proportion of the ultrasonic wave propagated to the housing 10 through the side wall 54 of the shield member 5 is extremely small. Therefore, a reduction in transmission loss of the ultrasonic wave can be achieved by use of the shield member 5 of this embodiment. From the viewpoint of further reducing the transmission loss, it is preferred that an inner surface of the side wall 54 of the shield member 5 is coated by an ultrasonic reflecting material, or an ultrasonic reflector is disposed on thereon. Moreover, as described before, since the shield member 5 has the tapered shape, it is possible to efficiently provide a focused liquid flow of the ultrasonic-applied cleaning medium from the opening 56 of the shield member.

As a modification of this embodiment, a liquid supply unit 20 shown in FIG. 7 may be used, which is characterized in that the transmission member 30 has a penetration channel 36 extending from the ultrasonic incident surface 31 to the ultrasonic radiation surface 33 thereof, and the liquid 2 is supplied into the chamber 11 (i. e. , the internal space of the shield member 5) through the penetration channel 36 and an aperture 57 formed in the bottom wall 52 of the shield member, as shown by the arrows in FIG. 7. In this case, since no

space for accommodating the pipe 26 in the housing 10 is needed, it is effective to downsize the ultrasonic cleaning device. In addition, to facilitate downsizing of the ultrasonic cleaning device, it is preferred to use a Langevin-type transducer as the ultrasonic transducer 40.

As another modification of this embodiment, as shown in FIG. 8, it is preferred that an elastic member 60 is put between the side wall 54 of the shield member 5 and the inner surface of said housing 10. In this case, even if minute vibrations of the shield member 5 occur, they can be absorbed by the elastic member 60 to stably hold the shield member in the housing 10. In addition, as shown in FIG. 9, it is preferred that the bottom wall 52 of the shield member 5 is tightly fixed to the ultrasonic radiation surface 33 of the transmission member 30 by use of a bolt 70. In this case, since the shield member 5 is excellent in resistance to vibration stress, it is useful to further reduce the transmission loss of the ultrasonic wave.

INDUSTRIAL APPLICABILITY As described above, according to the ultrasonic cleaning device of the present invention, even when using an ultrasonic wave having a relatively low <BR> <BR> frequency of, e. g. , several ten kHz, which is better suited for removing tough stains from an object to be cleaned, it is possible to provide a high cleaning effect, while minimizing transmission loss of the ultrasonic wave. In addition, since the ultrasonic radiation surface of the ultrasonic transmission member (i. e. , horn) do not contact the object during the cleaning operation, it is possible to safely clean parts of a living body with a liquid as the cleaning medium, to which the ultrasonic wave is being applied. From these advantages, it is expected that the ultrasonic cleaning device of the present invention will be widely used in various fields.