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US-12618425-B2 - Pneumatic drive device for translational and/or rotational movement

US12618425B2US 12618425 B2US12618425 B2US 12618425B2US-12618425-B2

Abstract

A pneumatic drive device includes a housing, a piston, and a first membrane. The first membrane and the piston are coupled to each other in such a way that an axial movement of the first membrane, caused by pressurizing a first pressure chamber, is converted into a translational movement of the piston. The pneumatic drive device also includes an output element, and a membrane. The membrane and the output element are coupled to each other in such a way that a circumferentially section-wise oscillating axial movement of the membrane, caused by circumferentially successive pressurization and depressurization of respective pressure chambers, is converted into a rotational movement of the output element.

Inventors

  • Marcus Braun

Assignees

  • TUEBINGEN SCIENTIFIC MEDICAL GMBH

Dates

Publication Date
20260505
Application Date
20230327
Priority Date
20220401

Claims (10)

  1. 1 . A pneumatic drive device for translational movement of an actuator shaft of a medical instrument, said pneumatic drive device comprising: a housing being substantially cylindrical; a piston mounted in the housing so as to be slidable along a longitudinal axis of the piston, a movement of the piston being configured to be coupled to a movement of the actuator shaft; a first membrane being elastically stretchable or expandable, the first membrane fixedly mounted in the housing, the first membrane defining a first pressure chamber, the first membrane being configured to be axially deflected by pressurizing the first pressure chamber, and the first membrane having a substantially ring-shaped cross-section such that a through-hole axially extends through the first membrane; and a piston rod coupled to the piston and axially extending through the through-hole of the first membrane, the first membrane and the piston coupled to each other in such a way that an axial movement of the first membrane, caused by pressurizing the first pressure chamber, is converted into a translational movement of the piston along the longitudinal axis of the piston, wherein the first membrane abuts the piston and expansion of the first membrane causes the piston to move along the longitudinal axis of the piston by pushing the piston; and a first plate fixed to the housing and a first sleeve fixed to the first plate, the first membrane being disposed between the first plate and the first sleeve.
  2. 2 . The pneumatic drive device according to claim 1 , wherein the through-hole is coaxial with the longitudinal axis of the piston.
  3. 3 . The pneumatic drive device according to claim 1 , wherein the first membrane and the piston are disconnected, and when the first membrane is deflected, the first membrane contacts the piston to push the piston in a longitudinal direction of the piston and towards a first side of the housing.
  4. 4 . The pneumatic drive device according to claim 1 , wherein the pneumatic drive device further comprises a second membrane, the second membrane being elastically stretchable or expandable, the second membrane fixedly mounted in the housing, the second membrane defining a second pressure chamber, and the second membrane being enabled to be axially deflected by pressurizing the second pressure chamber, wherein the second membrane and the piston are coupled to each other in such a way that an axial movement of the second membrane, caused by pressurizing the second pressure chamber, is converted into a translational movement of the piston along the longitudinal axis of the piston.
  5. 5 . The pneumatic drive device according to claim 4 , wherein the second membrane is arranged on a side of the piston opposite the first membrane.
  6. 6 . The pneumatic drive device according to claim 4 , wherein the second membrane and the piston are disconnected, and when the second membrane is deflected, the second membrane contacts the piston to push the piston in a longitudinal direction of the piston and towards the first membrane.
  7. 7 . The pneumatic drive device according to claim 4 , further comprising a second plate fixed to the housing and a second sleeve fixed to the second plate, the second membrane being disposed between the second plate and the second sleeve.
  8. 8 . A pneumatic drive device for rotational movement of an actuator shaft of a medical instrument, said pneumatic drive device comprising: (i) a housing being substantially cylindrical; (ii) an output element mounted in the housing so as to be rotatable about a longitudinal axis of the output element, a movement of the output element being configured to be coupled to a movement of the actuator shaft; (iii) a membrane being elastically stretchable or expandable, the membrane fixedly mounted in the housing, the membrane defining at least three pressure chambers arranged so as to be distributed in a circumferential direction, and the membrane being configured to be axially deflected in a circumferential region of the corresponding pressure chamber by pressurizing the respective pressure chamber, wherein the membrane and the output element are coupled to each other in such a way that a circumferentially section-wise oscillating axial movement of the membrane, caused by circumferentially successive pressurization and depressurization of the respective pressure chambers, is converted into a rotational movement of the output element about the longitudinal axis of the output element; (iv) a wobble plate being arranged axially between the membrane and the output element, a wobbling movement of the wobble plate converting the circumferentially section-wise oscillating axial movement of the membrane into the rotational movement of the output element; and (v) axial pistons arranged to transmit the circumferentially section-wise oscillating axial movement of the membrane onto the wobble plate; wherein the membrane has a substantially ring-shaped cross-section such that a through-hole axially extends through the membrane; and the pneumatic drive device further comprises an output element rod coupled to the output element, wherein the output element rod axially extends through the through-hole of the membrane.
  9. 9 . The pneumatic drive device according to claim 8 , wherein the through-hole is coaxial with the longitudinal axis of the output element.
  10. 10 . A drive system, comprising: (a) a first pneumatic drive device for translational movement of an actuator shaft of a medical instrument, said first pneumatic drive device comprising: (i) a first housing being substantially cylindrical; (ii) a piston mounted in the first housing so as to be slidable along a longitudinal axis of the piston, a movement of the piston being configured to be coupled to a movement of the actuator shaft; (iii) a first membrane being elastically stretchable or expandable, the first membrane fixedly mounted in the first housing, the first membrane defining a first pressure chamber, the first membrane being configured to be axially deflected by pressurizing the first pressure chamber, and the first membrane having a substantially ring-shaped cross-section such that a through-hole axially extends through the first membrane; (iv) a piston rod coupled to the piston and axially extending through the through-hole of the first membrane; and (v) a first plate fixed to the first housing and a first sleeve fixed to the first plate, the first membrane being disposed between the first plate and the first sleeve, the first membrane and the piston coupled to each other in such a way that an axial movement of the first membrane, caused by pressurizing the first pressure chamber, is converted into a translational movement of the piston along the longitudinal axis of the piston, wherein the first membrane abuts the piston and expansion of the first membrane causes the piston to move along the longitudinal axis of the piston by pushing the piston, (b) a second pneumatic drive device for rotational movement of the actuator shaft, said second pneumatic drive device comprising: (i) a second housing being substantially cylindrical; (ii) an output element mounted in the second housing so as to be rotatable about a longitudinal axis of the output element, a movement of the output element being configured to be coupled to a movement of the actuator shaft, the output element having an output element rod associated therewith; (iii) a second membrane being elastically stretchable or expandable and fixedly mounted in the second housing, the second membrane defining at least three pressure chambers arranged so as to be distributed in a circumferential direction, and being configured to be axially deflected in a circumferential region of the corresponding pressure chamber by pressurizing the respective pressure chamber, wherein the second membrane and the output element are coupled to each other in such a way that a circumferentially section-wise oscillating axial movement of the second membrane, caused by circumferentially successive pressurization and depressurization of the respective pressure chambers, is converted into a rotational movement of the output element about the longitudinal axis of the output element; (iv) a wobble plate being arranged axially between the second membrane and the output element, a wobbling movement of the wobble plate converting the circumferentially section-wise oscillating axial movement of the second membrane into the rotational movement of the output element; and (v) axial pistons arranged to transmit the circumferentially section-wise oscillating axial movement of the second membrane onto the wobble plate, wherein the first and second pneumatic drive devices share a common longitudinal axis, and wherein the piston rod and the output element rod are arranged radially nested with each other.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This U.S. Patent Application is a National Stage Patent Application in the United States claiming priority to PCT Patent Application No.: PCT/EP2023/057843 filed Mar. 27, 2023, which claims priority to German Patent Application Serial No.: 10 2022 107 857.4, filed Apr. 1, 2022, the contents of such applications being incorporated by reference herein in their entirety. FIELD OF THE INVENTION The present disclosure is directed to a pneumatic drive device for translational movement and/or for rotational movement of an actuator shaft of a medical instrument, in particular a minimally invasive instrument. BACKGROUND OF THE INVENTION For precisely moving the medical instrument and, in particular, for precisely actuation of the instrument as a result of the movement it is necessary to provide a drive device that can be precisely controlled. Motor-driven drive devices are already known from the state of the art. These devices drive the instrument by means of an electric motor, either directly or via a suitable gearbox. However, the disadvantage of this is that sufficient space must be available for the electric motor, which is a problem especially in the field of minimally invasive surgery. For a direct drive, it must be possible to couple the electric motor directly to the instrument, which in turn requires spatial proximity. However, this creates further problems with regard to supplying the electric motor with power and, above all, sterility of the electric motor, as the electric motor is usually designed as a multi-use component for cost reasons. In the case of a drive in which the movement is transmitted to the instrument via a suitable gearbox, there is the additional problem that the force generated by the electric motor does not act proportionally to the movement of the instrument due to losses in the gearbox, which in turn affects the controllability of the drive device. Further, pneumatic drive devices are already known form the state of the art. These devices drive the instrument by means of pressurizing a pressure chamber. The pressure chamber is formed by a piston sliding inside a cylinder. However, due to the necessary seal between the cylinder and the piston, friction occurs between them, resulting in the so-called “stick-slip effect”, in which the piston starts moving abruptly (due to static friction) and in which the applied force does not act proportionally to the movement of the instrument. In addition, leakage can occur between the piston and the cylinder, which could cause compressed air to escape from the drive device in the immediate vicinity of the patient, which must be avoided for reasons of patient safety. SUMMARY OF THE INVENTION The gist of the present disclosure is that a piston to be moved does not define/limit the pressure chamber, for which the piston would have to be mounted in a (as far as possible) gas-tight manner to an inner wall of a housing/cylinder, but at the same time in a movable manner relative to the inner wall of the housing. In this case, the gas-tight mounting of the piston would necessarily cause a certain amount of friction between the piston and the housing, which in turn would affect the displaceability, i.e. the force required for the displacement, and in particular cause the stick-slip effect mentioned above. Thus, by providing an additional membrane for surrounding the pressure chamber in a gas-tight manner, on the one hand, the tightness of the pressure chamber as such can be better guaranteed (and thus, improving patient safety, in particular, ensuring sterility) and on the other hand, the piston can be accommodated in the housing almost frictionless, which means that the applied pressure is almost proportional to the generated movement, so that the drive device can be controlled extremely precisely. Further, a limitation of maximum forces is possible. For avoiding the stick-slip effect during expansion/deflection of the membrane as far as possible, friction between the membrane and surfaces contacted by the membrane, such as the inner wall of the housing, must be prevented or reduced to avoid losses and thus, to ensure proportionality between pressure and movement, for example by selecting suitable materials for the membrane. In particular, the membrane may be made from a thermoplastic elastomer. Further, the membrane may preferably have good sliding properties on its outer side by choosing an adequate material or providing the membrane with an adequate coating. At the same time, the membrane should be designed in such a way that the reversible expansion/deflection of the membrane is possible, which can be achieved, for example, by a suitable choice of material, in particular with a high elasticity, i.e. an elasticity greater than 200%, preferably greater than 400%, or a corresponding geometrical design, in particular as a bellows/accordion, with axial zigzag folding, or the like. According to a first aspect of the di