Self-advancing device

This application is a continuation of U.S. application Ser. No. 10/499,426 filed Sep. 13, 2004 (issued on Jan. 27, 2009 as U.S. Pat. No. 7,481,764), which is a National Stage application of PCT Application No. PCT/AU02/01733, filed on Dec. 20, 2002, which claims priority to Australian Patent Application Nos. PS 1610/02 (filed on Apr. 8, 2002), PS 0647/02 (filed on Feb. 21, 2002), and PR 9678/01 (filed on Dec. 20, 2001). Each of the above-referenced applications is incorporated by reference in its entirety.

1. Field

The invention relates to a self-advancing device particularly, but not exclusively, for use in the field of medical instrumentation.

2. Description of the Related Art

A number of self-advancing mechanisms are used in the medical industry to advance instruments, such as an endoscope, internally of a patient\'s body.

Self-advancing endoscopes are disclosed in, for example, U.S. Pat. No. 4,934,786, U.S. Pat. No. 5,345,925 and U.S. Pat. No. 5,562,601. The devices disclosed in these patents all rely on the outer surface of the endoscope having a relatively movable portion that grips the internal wall of a passage through which the endoscope is passing. In that manner, the endoscopes rely on external pushing as their source of forward motion and the resultant construction of the mechanisms to achieve that motion can be relatively complex.

Another endoscope is disclosed in International Application No. PCT/AU99/00005, which is propelled forwardly by a piston slidably mounted within a tubular member of the endoscope. The piston is caused to move toward and impact on a distal end wall of the endoscope to provide forward motion. A wire or other mechanism is used to retract the piston for subsequent acceleration and impact with the end wall, in order to further advance the endoscope. A disadvantage of such an arrangement is that the impact of the piston can produce an uncomfortable sensation within the patient and the use of a retracting wire may complicate construction of the endoscope and compromise operating efficiency, such as due to frictional resistance between the tubular member and the wire.

In accordance with embodiments of the invention, there is provided a device which includes an elongate body with a movable mass arranged for sliding movement within the body, the element being arranged to decelerate toward an end of the body in order to impart forward movement thereto, via momentum transfer, and being arranged to accelerate away from said end in order to further drive the body forward, again using momentum transfer.

In certain embodiments, the mass is a piston element.

In some embodiments, the element is driven under action of a fluid and the device includes control means to allow fluid flow between the element and the body to be controlled so as to effect deceleration and acceleration of the element toward and away from the end of the body.

The device may define a first flow path for applying pressurized fluid to a rear of the element and a second flow path for allowing the fluid to be discharged from between a front of the element and the end of the body, wherein fluid flow along the second flow path is reduced as the element approaches the end of the body, in order to provide a fluid cushion to dampen impact between the element and the body. A third flow path may also be provided to inject fluid between the element and the end of the body, in order to accelerate the element in a rearward direction relative to the end of the body, fluid flow along the third flow path being established when the element is adjacent the end of the body.

In certain embodiments, a sensor is provided to determine the proximity of the element relative to the end of the body.

In one arrangement, the second flow path is provided in a conduit, which extends axially through the element and the body, and the third flow path is also through the conduit, in a reverse direction to the second flow path.

In an alternative arrangement, the element slides in a channel, within the body, and a conduit extends axially through the channel and the element, for providing pressurized fluid to the device, wherein valves are arranged in the conduit to direct the pressurized fluid into a region between a rear of the body and a rear of the element, along the first flow path, and to direct fluid from the conduit along the third flow path, into a second region, in front of the element, for driving the element in a reverse direction, and wherein the second flow path passes through openings formed in the channel and into a return passage formed in the body fluid to exit the second region along the second flow path, as the element is moved forward.

The valves may include a main valve positioned in a forward end of the conduit and secondary valves arranged adjacent the first region, wherein a positive fluid pressure is maintained in the conduit and the valve is in a closed condition when the element travels in a forward direction, so that fluid is directed through the secondary valves, into the first region between the conduit and the body, to drive the element in the forward direction.

Additional valves may be provided to vent fluid captured between a rear end of the body and the element directly into the second flow path, when the element is moved rearward of the body.

In another aspect, there is provided a self-advancing probe, including a device, as described above.

The probe may be provided with a light source and camera. The probe may also include location means for securing the probe relative to adjoining structure.