The invention relates to a device for mounting a hollow needle on a phaco instrument handpiece and for demounting the hollow needle from the phaco instrument handpiece. This surgical instrument may be, for example, a phacoemulsification handpiece, a phaco irrigation handpiece, a phaco suction handpiece, or a combined phaco irrigation/suction handpiece.
In ophthalmology, a surgical instrument is used to treat the eye lens, said surgical instrument having a phacoemulsification handpiece with a hollow needle screwed thereto. It is known to screw the hollow needle onto the handpiece by using torque-limiting manually operable tools. As an example of this related art, reference is made to CN-A-108992744, WO-A-2011/149727, US-A-2009/157009 and US-A-2014/0100515. The torque-limiting tools described in these two documents are quite elaborate in design.
An object of the invention is to provide a device for mounting and demounting a hollow needle on and from a phaco instrument handpiece, the device having a simple design and no torque limitation for demounting the hollow needle from the phaco instrument handpiece.
To achieve this object the invention provides a device for mounting and demounting a hollow needle on and from a phaco instrument handpiece, the device being provided with
Thus, the invention provides a device having a manually operable housing which can be gripped by the fingers of a hand and in which a rotary shaft is rotatably mounted. Furthermore, a driver element is arranged inside the housing, wherein the driver element can be part of the housing or can be an element separate from the housing. The driver element rotates along with the housing when the housing is rotated by hand. Between the driver element and the rotary shaft there is a torque limiting and non-return coupling which has two coupling surfaces resiliently pressed against each other. One of said coupling surfaces is located on the rotary shaft, while the other coupling surface is located on the driver element. Typically, both coupling surfaces are configured as radial contact surfaces extending radially to the rotary shaft.
The rotary shaft also comprises a plug-on end which is led out from an opening of the housing and forms a receiving recess that is plugged on the hollow needle when the hollow needle is to be mounted or demounted. The hollow needle is typically provided with recesses on its outside into which engaging projections on the inside of the receiving recess of the plug-on end immerse. Alternatively, the hollow needle can have engaging projections on its outside to be received in recesses on the inside of the receiving recess of the plug-on end. In both cases, a kind of form-fit is created, whereby the hollow needle is also rotated when the housing is rotated manually.
The two coupling surfaces are provided with coupling release projections and coupling recesses that are complementary with respect to their form. The projections can all be arranged on the one coupling surface and the complementary coupling recesses can all be arranged on the other coupling surface. However, it is also possible that projections and recesses are formed on both coupling surfaces. According to the invention, at least one coupling release projection and at least one coupling recess are required. Due to the resilient pretensioning of the two coupling surfaces, said coupling surfaces rest against each other and the coupling release projections are immersed in their associated coupling recesses until the torque exceeds a limit value. The size of this value depends on design, for example, one the one hand, on the force with which the two coupling surfaces rest against each other, and, on the other hand, on the design (i.e. geometry) of the coupling release projections and coupling recesses. Typically, the coupling release projections and the coupling recesses are spherically formed (for example as a hemisphere or half shall).
To ensure that the torque limitation is only effective when the hollow needle is screwed onto the phaco instrument handpiece (hereafter referred to as a phacoemulsification handpiece, representative of such instruments), a non-return device is provided in the device according to the invention. Said non-return device comprises non-return projections and non-return recesses at the coupling surfaces, wherein it also applies here that all non-return projections are arranged on the one coupling surface and all non-return recesses are arranged on the other coupling surface, or that both coupling surfaces have non-return projections and non-return recesses. According to the invention, at least one non-return projections and at least one non-return recess are required.
The relative arrangement of the non-return projections and the non-return recessed is selected according to the invention such that each non-return projection can shift in its associated non-return recess in the one direction of rotation of the housing about the axis of the rotary shaft, this direction of rotation being the direction in which the torque limitation acts. In this direction of rotation, the coupling release projections then move out of their coupling recesses when the maximum permissible torque is reached, spacing both coupling surfaces by the height of the coupling release projections. In this condition, the non-return projections are also moved out of their non-return recesses. According to the invention, the non-return projections are now flatter than the coupling release projections, i.e. they have a lower height than the coupling release projections when viewed in the axial extension of the rotary shaft. Each non-return recess has two ends or end stops located in the direction of rotation of the housing and opposite thereto. Before a non-return projection, which is immersed in the non-return recess associated thereto, reaches the end located in the direction of rotation in which the torque limitation acts, the non-return projection is already lifted out of the non-return recess when the torque limitation is exceeded, since the coupling release projections are moved out of the coupling recesses. In contrast, each non-return projection in the non-return recess already rests against its other end when the coupling release projections are positioned in the coupling recesses. This means that the non-return projections in the opposite direction of rotation do not allow the coupling release projections to move out of the coupling recesses, which means that the torque limitation in this opposite direction of rotation is cancelled and therefore inactive.
The coupling release projections and the coupling recesses can be arranged on circular lines that are concentric to the axis of the rotary shaft and are aligned with each other, i.e. have the same radius. Similarly, the non-return projections and the non-return recesses may be arranged on circular lines that are aligned with each other. Typically, however, the circular lines of the coupling release projections and recesses are different from those of the non-return projections and recesses, but this does not necessarily be the case.
In a further expedient embodiment of the invention, it may be provided that the one coupling surface has several coupling release projections and the other coupling surface has a number of coupling recesses equal to the number of coupling release projections, or has a number of coupling recesses which is larger by a factor of 2 or 3 or more than the number of coupling release projections, wherein the relative arrangement of a number of coupling recesses equal to the number of coupling release projections is equal to the relative arrangement of the coupling release projections.
In a further expedient embodiment of the invention, it may be provided that the one coupling surface has a larger number of non-return recesses than there are non-return projections on the other coupling surface.
It may also be expedient if the number of non-return recesses is equal to or larger than the number of non-return projections by a factor of 2 or 3 or more.
It may also be advantageous if the one coupling surface has three coupling release projections each offset by 1200 relative to one another and the other coupling surface has six coupling recesses each offset by 60° relative to one another, and if the one coupling surface has three non-return projections each offset by 1200 relative to one another and the other coupling surface has six non-return recesses each offset by 600 relative to one another, wherein the non-return recesses are each arranged in alignment with the center between two coupling recesses.
In a further expedient embodiment of the invention, it may be provided that the at least one or each coupling release projection and the at least one or each coupling release recess are arranged on a first circular line being concentric to the rotary shaft, and that the at least one or each non-return projection and the at least one or each non-return recess are arranged on a second circular line being concentric to the rotary shaft and different from the first circular line. However, it is also possible that coupling release recesses and coupling release projections are distributed along several first circular lines and that correspondingly non-return projections and non-return recesses are distributed along several second circular lines.
In a further expedient embodiment of the invention, it is provided that the rotary shaft in the housing is rotatably mounted by means of bearing bushes, and/or that the rotary shaft extends through the driver element, and/or that a helical compression spring is arranged concentrically on the rotary shaft, the helical compression spring extending and being supported between a support surface in the hosing and a support surface on the rotary shaft, and/or that the driver element is pressed by a helical compression spring against the rotary shaft.
Finally, it is also conceivable that the at least one or each engaging projection and/or the at least one or each coupling release projection is spherically formed, and/or that the at least one or each non-return projection and the at least one or each non-return recess comprise contact surfaces extending at right angles or substantially at right angles to the coupling surfaces and resting against each other when the at least one coupling release projection is immersed in the at least one coupling recess.
The device according to the invention is expediently made entirely or quite predominantly of plastic material (for example in the form of plastic injection-molded parts), which applies in particular to the coupling. The more non-return projections are provided, the more shear-resistant the coupling surfaces rest against each other when it comes to unscrewing the hollow needle.
In the following, the invention is described in more detail by means of an exemplary embodiment and with reference to the drawing, in which
The rotary shaft 18, together with a driver element 32, forms a torque limiting and non-return coupling 34 (hereinafter referred to as a coupling for convenience only) having a first coupling surface 36 and a second coupling surface 38. The first coupling surface 36 is formed in this embodiment as a radial contact surface 40 on the rotary shaft 18, while the second coupling surface 38 is formed as a radial contact surface 42 of the driver element 32. Both coupling surfaces 36, 38 are resiliently tensioned against each other by means of a spring 44, which in this exemplary embodiment is designed as a spiral compression spring. The rotary shaft 18 is rotatably mounted within the housing 16 via bearing sleeves 46, 48, 50. Meanwhile, the rotary shaft 18 penetrates the driver element 32. The spring 44, which is seated coaxially on the rotary shaft 18, is located on the side of the driver element 32 facing away from the first coupling surface 36. A closing cover 52 is located at the end of the housing 16 facing away from the opening 20 for the plug-on end 22 of the rotary shaft 18. The spring 44 is supported, on the one hand, on a support surface in the housing 16 (not shown) and, on the other hand, on a support surface 45 arranged on the driver element 32, facing away from the second coupling surface 38 of the driver element 32.
The driver element 32 is arranged in the housing 16 in a form-fit manner. For this purpose, the driver element 32 has two circumferential recesses 54 which engage with internal driver lugs (not shown) in the housing 16. Thus, when the housing 16 is rotated, the driver element 32 is rotated therein as well, wherein it can shift axially on the rotary shaft 18 without that the driver lugs of the housing 16 become disengaged from the circumferential recesses 54.
The essential element of the device 10 is the coupling 34, which is shown again in perspective view in
The coupling 34 according to the invention serves to provide a torque limitation in the one of two opposite rotational movements of the housing 16. This rotational movement is the rotational movement by which the housing must be rotated in order to screw on the hollow needle 12. The further function of the coupling 34 is to exclude torque limitation in the opposite direction of rotation of the housing 16. In the following, this non-given torque limitation is also called “non-return”, which means that the torque limitation is blocked, i.e. cancelled.
In the condition of the coupling engagement (see, e.g.
In the reverse case, i.e. when the housing 16 is twisted to unscrew the hollow needle 12, the initial situation is again as shown in
Number | Date | Country | Kind |
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19171418.7 | Apr 2019 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/054376 | 2/19/2020 | WO | 00 |