JPH04300177A - Actuator - Google Patents

Abstract

PURPOSE:To provide a fluid-driven actuator adapted to be used in a micromachine. CONSTITUTION:A hydraulic fluid feed passage 13 is defined by an annular space between outer and inner pipes 2, 3 which are coaxially arranged. Meanwhile, a return passage 14 is defined in the inner pipe 3 in which an output shaft 9 coupled to a turbine 10 is rotatably supported. A plurality of nozzles 12, 12... facing turbine blades 11 of the turbine 10 are formed in the inner pipe 3. Hydraulic fluid fed through a feed passage 13 is jetted from these nozzles 12 so as to rotate the turbine 10 for rotating the output shaft 9, and the hydraulic fluid having passed through the turbine 10 is recovered by the return passage 14. With this arrangement, the turbine 10 having a very small diameter may be efficiently rotated. Further, the hydraulic fluid may be recovered by way of the return passage 14 within an actuator 1.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an actuator,
In particular, it relates to formed actuators of fluid-driven turbines used in micromachines.

0002

[Prior Art] In recent years, as an example of using micromachines in the medical field, plans have been advanced to incorporate minute driving parts and mechanical parts into part of catheters inserted into the human body to diagnose and treat patients. It's coming. This type of micromachine is inserted into the human blood vessel and guided to the diagnostic site, so its dimensions are generally diameter φ =
It is set to be 2 mm or less, and furthermore, minute drive parts and mechanical parts are incorporated inside it. FIG. 3 shows an example of the actuator portion of this micromachine. In FIG. 3, reference numeral 20 indicates an actuator made of an elastic tube, and a working fluid flowing through the actuator 20 rotates an axial flow turbine 21 housed therein. This axial flow turbine 21 is fixed to a rotating shaft 22 and rotatably supported by bearings 23 and 24. In addition, this axial flow turbine 21
A plurality of turbine blades 25, 25, . . . are formed on the surface of the turbine. The turbine blades 25 are provided with a helix angle of a predetermined angle in the axial direction, and when the working fluid flows in the direction of arrow A, the working fluid passes between the turbine blades 25 and the circumferential direction that occurs at that time. The force drives the turbine blades 25 to rotate. Furthermore, the working fluid that has passed through the turbine blade 25 is discharged to the outside of the actuator via the outflow holes 26, 26, . . . . In addition to gases such as air, physiological saline and blood may be used as the working fluid in consideration of their compatibility with the human body.

0003

However, in the above-mentioned actuator, an axial thrust force is generated as an axial component of the working fluid acting on the turbine blade. There is a problem in that this thrust force causes frictional force in the bearing, reducing the rotational driving force. Furthermore, since the flow direction of the working fluid is defined in one direction, the working fluid is discharged to the output side outside the actuator after the actuation. Therefore, when this actuator is used inside a human body, the working fluid is discharged into the human body. This is undesirable from a medical standpoint. Furthermore, if a recovery device is added separately, the actuator will inevitably become larger. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an actuator that can eliminate the problems of the above-mentioned conventional techniques and can circulate a working fluid within the actuator to rotate a turbine blade and recover the working fluid.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention arranges an outer tube and an inner tube coaxially, and operates an annular portion formed between the outer tube and the inner tube. The inner pipe is used as a fluid sending flow path, while the inner pipe is used as a return flow path, a turbine is fixed to an output shaft rotatably supported in the inner pipe, and a plurality of nozzles are bored in the inner pipe, and these nozzles The working fluid supplied through the feed passage is injected from the turbine to rotate the turbine to rotationally drive the output shaft, and the working fluid is recovered from the return passage. It is something.

[0005]

[Operation] According to the present invention, the outer tube and the inner tube are disposed coaxially, and the annular portion formed between the outer tube and the inner tube is used as a flow path for feeding the working fluid. The inside of the pipe is used as a return flow path,
A turbine is fixed to an output shaft that is rotatably supported in the inner tube, and a plurality of nozzles facing the turbine blades of the turbine are bored in the inner tube, and a plurality of nozzles are supplied from these nozzles through the feed flow path. Since the working fluid is injected to rotate the turbine and rotate the output shaft, and the working fluid is recovered from the return flow path, it is possible to efficiently rotate a turbine with a small diameter. At the same time, the working fluid discharged from the turbine can be recovered via a return flow path within the actuator.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the actuator according to the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows the distal end portion of an intravascular catheter, etc., which is in the form of a long and narrow tube with cylindrical flexibility. An actuator 1 that generates a rotational driving force for performing treatment within the body is provided at this distal end. The actuator 1 is covered with an outer tube 2, and the outer tube 2 constitutes an elastic tube made of flexible silicone rubber or the like. Furthermore, an inner tube is coaxially arranged inside the outer tube 2 with a predetermined gap therebetween. This inner tube 3 is also made of the same material as the outer tube 2 and can be curved integrally with the outer tube 2. Further, a stainless steel inner casing 4 is connected to the tip of the inner tube 3, and a plug 5 is fitted to the tip of the inner casing 4, and the plug 5 seals the tip of the inner casing 4. It has been stopped. Further, a spacer ring 6 is interposed at the tip between the inner casing 4 and the outer tube 2, and the spacer ring 6 maintains a gap between the outer tube 2 and the inner casing 4. Further, the end face of the actuator 1 has a flange 5 formed integrally with the plug 5.
The entire surface is covered by a. on the other hand,
A bearing 7 is fitted inside the inner casing 4, and a plurality of through holes 7a are bored in the bearing 7 in the axial direction. Further, an output shaft 9 is rotatably supported by this bearing 7 and a bearing 8 formed on the plug 5. Furthermore, a turbine 10 having a diameter slightly smaller than the inner diameter of the inner casing 4 is fitted onto the output shaft 9. This turbine 10 has eight turbine blades 1 as shown in FIG.
1, 11... are formed by electric discharge machining, and four nozzles 12, 12... are formed so as to face this turbine blade 11.
is bored in the inner tube 3. The direction of this nozzle 12 is set to face the center of the blade surface of the turbine blade 11,
The turbine 10 can be rotated most efficiently.

[0007] Here, the operation of the actuator 1 for rotating the turbine 11 having the above-mentioned configuration will be explained. An annular flow path 13 is provided in the annular portion sandwiched between the outer tube 2 and the inner tube 3.
is formed. Working fluid supplied from an external pressure source (not shown) flows in the annular flow path 13 in the direction of arrow A, and the pressurized working fluid flows through the annular flow path 13.
The liquid is continuously injected from the nozzle 12 at the tip of the tube 3 toward the turbine blade 11 inside the inner tube 3 . This causes the turbine 10 to rotate. This turbine 10
The rotation speed can be controlled to some extent by the pressure of the working fluid supplied. The working fluid that rotates this turbine 10 is supplied to the through holes 7a, 7a, . . . formed in the bearing 7.
Arrow B indicates the inside of the return flow path 14 formed in the inner tube 3 through
It flows toward the direction and can be collected at the mouth of the actuator 1.

When the actuator 1 is used on the human body, it is preferable to use a material that does not cause any harm even if the working fluid flows out of the actuator. For example, physiological saline or the like can be used. Further, as a structural improvement of this actuator 1, it is also possible to provide a cantilever-supported rotating shaft structure with only a bearing 8, without using the bearing 7 of the above embodiment. This allows the return flow path within the inner tube 3 to be made larger, and it also becomes possible to supply higher pressure working fluid to the turbine. At this time, it is preferable to consider the structure and shape of each part so that cavitation does not occur inside the pipe due to the working fluid flowing at high speed. Further, the inclination angle, position, arrangement, number of turbine blades, and shape of the nozzle bored in the inner tube 3 can be determined according to the required output of the actuator.

[0009]

As is clear from the above description, according to the present invention, the outer tube and the inner tube are arranged coaxially, and the annular feeding flow path formed between the outer tube and the inner tube is The working fluid supplied through the inner pipe is injected through a nozzle formed in the inner pipe to rotate the turbine and rotationally drive the output shaft, and the working fluid is circulated and recovered through a return passage formed in the inner pipe. As a result, it is possible to efficiently rotate a turbine having a small diameter, and the working fluid can be reliably recovered from the actuator.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an actuator according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1;

FIG. 3 is a perspective exploded view showing an example of a conventional actuator of this type.

[Explanation of symbols]

2 Outer tube 3 Inner pipe 7, 8 Bearing 9 Output shaft 10 Turbine 11 Turbine blade 12 Nozzle 13 Annular feeding channel 14 Return flow path

Claims (1)

[Claims] Claim 1: An outer tube and an inner tube are disposed coaxially, and an annular portion formed between the outer tube and the inner tube is used as a flow passage for a working fluid, while a return flow is provided in the inner tube. A turbine is fixed to an output shaft that is rotatably supported in the inner tube, and a plurality of nozzles are bored in the inner tube, and the working fluid is supplied from these nozzles through the feed channel. An actuator characterized in that the working fluid is injected to rotate the turbine and rotationally drive the output shaft, and the working fluid is recovered from the return flow path.