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Dokumentenidentifikation EP0730710 26.10.2000
EP-Veröffentlichungsnummer 0730710
Titel INHALATOR MIT EINRICHTUNG FÜR DREHMOMENTÜBERTRAGUNG IN EINER DREHRICHTUNG
Anmelder AstraZeneca AB, Södertälje, SE
Erfinder HODSON, David, Peter, Saint Paul, US;
HOWGILL, John, Stephen, Saint Paul, US;
WASS, Charles, Anthony, Saint Paul, US
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 69425978
Vertragsstaaten AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LI, LU, MC, NL, PT, SE
Sprache des Dokument EN
EP-Anmeldetag 21.11.1994
EP-Aktenzeichen 959035825
WO-Anmeldetag 21.11.1994
PCT-Aktenzeichen US9413464
WO-Veröffentlichungsnummer 9514867
WO-Veröffentlichungsdatum 01.06.1995
EP-Offenlegungsdatum 11.09.1996
EP date of grant 20.09.2000
Veröffentlichungstag im Patentblatt 26.10.2000
IPC-Hauptklasse F16D 41/18

Beschreibung[en]
Field of the Invention

This invention relates to an inhaler comprising a device for the transmission of one-way torque and in particular to a device which may readily be moulded from plastics and can transmit high driving forces.

Background

Devices for transmission of one-way torque are well known, common examples include a socket wrench and the winding mechanism of a clockwork motor, watch, clock etc. Generally such devices comprise at least one metal part and a biasing spring to bias a pawl in engagement with the teeth of a ratchet wheel.

W090/13328 discloses a dry powder inhalation device comprising a housing defining a chamber in communication with a patient port in the form of a mouthpiece or nasal adaptor, and an elongate carrier bearing a powdered medicament, the device being constructed and arranged such that areas of predetermined size of the elongate carrier may sequentially be exposed within the chamber, the device comprising one or more air inlets such that when a patient inhales through the patient port an air flow is established from the air inlet(s) to the patient port through the chamber such that particles of the powdered medicament of respirable size from said exposed area of the elongate carrier are entrained within the air flow.

The elongate carrier is preferably in the form of a tape having a surface with grooves, pores, apertures or other embossed features which contain particles of medicament. The tape is conveniently wound on a supply spool and preferably contained within a cassette having a supply and take-up spool. The tape may contain many doses of the drug e.g. 200 doses.

In use, areas of the tape are sequentially advanced into the chamber to dispense the medicament contained within that area of tape. It is essential that the tape is advanced in well defined steps from the supply to the take-up spool to facilitate accurate, reproducible dosing and to prevent drug wastage. The advancement of the tape is conveniently facilitated by pivotal movement of a lever, either in a similar manner to the winder lever of a camera, or more preferably in the form of a mouthpiece cover, such that the tape is automatically advanced when the patient opens the cover. Such arrangements require an efficient one-way drive providing precisely controlled advancement and so that closure of the cover causes no movement of the tape.

The requirements of such a drive mechanism for use in an inhaler are manifold. It is desirable that the mechanism be cheap, preferably injection moulded in a minimum number of plastic parts. The device should be compact and lightweight, able to transmit large drive forces in relation to the torque needed to reverse the mechanism, capable of achieving low levels of variation in any lost motion, reliable, able to withstand temperatures of -20°C to +70°C for several hours without creeping or stress relaxing when "parked" in any configuration, able to resist wear and tear after prolonged usage (several thousand operations in each direction), reasonably immune to dirt or powder ingress, cheap to assemble, and quiet in operation.

The invention has been made with the above points in mind.

According to the present invention there is provided an inhaler having an elongate carrier bearing powdered medicament and an advancement means for moving the carrier to position an area of the carrier in a predetermined place for dispensing medicament, characterised in that the advancement means comprises a device for the transmission of one-way torque comprising:

  • an outer annular member (2) having a plurality of radially inwardly projecting teeth (4), each tooth (4) comprising a driving surface (6) and a cam surface (8),
  • a shaft (10) concentrically mounted with respect to the outer annular member, the shaft comprising a plurality of drive elements (12, 14) each having a driving surface (18, 20) and a cam surface (22, 24) two of said drive elements being interconnected to form a slider (16) extending substantially diametrically across the shaft, said drive elements being mounted on the shaft in a manner allowing radial movement relative to the shaft, whereby:
  • rotation of the shaft or outer annular member in its driving direction causes engagement of a driving surface (18, 20) of at least one drive element (12, 14) with a driving surface (6) of at least one tooth (4) thereby resulting in joint rotation of the shaft and outer annular member, and
  • rotation of the shaft or outer annular member in its non-driving direction causes engagement of the cam surface (22, 24) of at least one drive element (12, 14) with the cam surface (8) of at least one tooth resulting in additional relative movement, substantially radially, between said drive element and said tooth thereby preventing rotational movement being transmitted between said shaft and said outer annular member,
  • said engagement of the driving surfaces and the cam surfaces not requiring the presence of spring biasing means.

The driving surfaces of the teeth and slider or pawl are preferably substantially radial and the length of the slider or pawl allows engagement of only one of the drive elements at a time.

Either the shaft or the outer annular member may be connected to a drive means e.g. lever, inhaler cover etc. Preferably the drive means is connected to the shaft. The outer annular member may be axially connected to a spool etc. or may comprise gear teeth moulded onto its radially outer surface which may be used to drive a spool etc. via a gear wheel.

The invention will now be described with reference to the accompanying drawings in which:

  • Figure 1 represents a cross-section through a device for transmission of one-way torque suitable for use in an inhaler in accordance with the invention.
  • Figure 2 represents a cross-section through a modified device of the type shown in Figure 1.

Figure 1 shows a cross-section through a transmission device for use in the invention comprising an outer annular member (2) having 16 inwardly projecting teeth (4) each comprising a driving surface (6) and a cam surface (8). The annular member (2) may be a gear wheel having gear teeth (not shown) projecting radially outwardly.

A shaft (10) is concentrically mounted within the outer annular member (2) and is associated with two drive elements (12,14) which are joined to form a slider (16). Each drive element (12,14) comprises a driving surface (18,20) and a cam surface (22,24). The slider (16) is located within channel (26) within the shaft (10) and is free to reciprocate in the radial direction. In order to minimise friction between the slider (16) and the walls of the channel the surface areas in contact are reduced by the presence of rounded projections (28) extending from the wall of the channel (26). It will be appreciated such projections may equally well be present on the slider (16). The shaft (10) may be attached to a lever (not shown) e.g. the pivoting cover of an inhaler, to cause rotional movement of the shaft (10).

When the shaft (10) is rotated clockwise the driving surface (18) of the drive element (12) will engage the driving surface (6) of a tooth (4) causing the outer annular member (2) to be rotated through the same angle. If the rotation of the shaft (10) is reversed the slider (16) will be caused to reciprocate as the cam surface (22) of the drive element (12) will engage the cam surface (8) of a tooth causing radial movement of the slider (16) in one direction and thereafter the cam surface (24) of the drive element (14) will engage the cam surface (8) of a different tooth (4) causing radial movement of the slider (16) in the opposite direction. Thus no driving force will be transmitted to the annular outer member (2) and the shaft is free to rotate. Thus, this embodiment of the invention is effectively a form of escapement with the slider (16) reciprocating to allow the teeth (4) to escape past it at alternate ends.

Due to the shallow tooth angle of the teeth (4) there is more force tending to cause reciprocation of the slider (16) than back rotation of the outer annular member (2). In practice, there is likely to be enough friction in any gear train etc. of which the outer annular member may form a part, and low enough friction of the slider in its channel, to ensure that back rotation of the outer annular member does not occur. One of the major advantages of inhaler drive mechanisms according to this embodiment has been found to be the complete lack of back rotation of the outer annular member (2).

Another advantage is the consistency of the lost motion in the device of Figure 1. Consider a back rotation (free wheeling) action of the shaft followed by a reversal i.e. driving action. If the reversal occurs at a random position, then the next driving point will be reached after between about 0° and 360°/32 of lost motion, i.e. there will be a random amount of lost or wasted motion of up to approximately 11°. Obviously more teeth (4) on the outer annular member (2) would reduce the maximum possible lost motion, but at the expense of requiring smaller teeth with less strength. Consider reciprocation of the shaft between two given positions, as would happen if the shaft were fixed to an inhaler mouthpiece cover which was being repeatedly opened and closed by a patient, for example. Although there would still be lost motion, it would be constant, as each driven tooth would be contacted, and subsequently left, at consistent positions. The approximately 11° angle between adjacent drive positions provides an estimation of the tolerance of the system to variations in shaft freewheeling angle. If the shaft is rotated by 5° less than usual in the freewheeling direction e.g. the inhaler mouthpiece cover is not completely closed, then the next shaft drive cycle, linked to the mouthpiece cover opening, will be 5° shorter than usual, but the 5° will be subtracted from the lost motion, so that the driven rotation of the outer annular member, causing advance of drug coated tape, will be the usual full amount.

A further advantage of the device is the lack of potential creep of such a plastic ratchet mechanism. Most known ratchets require springs of some nature for them to operate correctly. The choice is usually either a metal spring, which can be expensive, hard to produce accurately to small tolerances, and may cause substantial wear of other fine plastics parts, or a plastics spring which will suffer from creep or stress relaxation if parked under any significant loading force at elevated temperatures. Most simple fine scale plastics ratchet mechanisms are unable to ensure that parking cannot occur with a spring in a loaded configuration and leaving most such mechanisms in a hot car in bright sunshine, a few hours at 50°C, for example, would be sufficient for enough creep to occur to prevent the ratchet functioning properly again. The device of Figure 1 has no spring function, however, so is not susceptible to such a creep problem.

In an alternative embodiment (not shown) of the device of Figure 1, eight teeth inside the outer annular member were present, each deeper. This arrangement thus provides larger teeth of higher strength and greater tolerances. Although the device has fewer drive positions, eight teeth and two slider ends giving sixteen drive positions, it is possible to be more certain which will engage if the shaft is rotated by an angle which varies slightly, i.e. there is a large tolerance on the freewheeling angle. For example, consider a lever attached to the shaft being reciprocated by around 165° each time. Each stopping point corresponds to 360°/16=22.5°, so that 165° is equivalent to seven times the angle between drive positions plus 7.5° slack. In other words, there will be approximately 7.5° of wasted motion of the shaft each time, but exactly 7 x 22.5°=157.5° of outer annular member rotation, i.e. the drive should theoretically provide a consistent 157.5° one-way rotation of the outer annular member as the shaft is reciprocated repeatedly by approximately 165°. Tests of this device showed the expected mean rotation of the outer ring, with a standard deviation of the rotation angle of less than one and a half degrees.

Whilst the device of Figure 1 does not require a spring biasing means for operation since the slider is free to move entirely under the influence of the teeth (4) it is possible to provide a bistable biasing action which causes a snap action during radial movement. Figure 2 shows the slider (16) provided with two plastic spring wings (30), the ends of which are retained within recesses (32). The wings (30) may be formed integrally with the slider (16). The wings (30) have a bistable action tending to move the slider (16) towards one of its ends or the other with a snap action. Full engagement of a drive element at the end of the slider with a tooth (4) will thus tend to be more assured, reducing the possibility of tip wear of the slider due to large torques being transmitted via too small a tip/tooth overlap. Even if the slider (16) is left with the plastic spring wings (30) strained i.e. cammed towards but not beyond the centre position by a tooth (4), any stress relaxation of the spring wings occurring with time, although reducing the snap of the over-centre action of the slider in one direction, will not prevent the slider operating as in Figure 1 since the operation is dependent upon the teeth (4) and not the spring bias.


Anspruch[de]
  1. Inhaliergerät mit einem länglichen Träger, der ein pulverförmiges Medikament aufnimmt, und einem Fortbewegungsmittel zum Bewegen des Trägers, um einen Bereich des Trägers an einem vorbestimmten Ort zur Ausgabe des Medikamentes zu positionieren, dadurch gekennzeichnet, dass das Fortbewegungsmittel eine Vorrichtung zur Übertragung eines Drehmomentes in einer Richtung aufweist, die folgendes umfasst:
    • ein äußeres Ringelement (2) mit einer Mehrzahl von radial nach innen vorstehenden Zähnen (4), wobei jeder Zahn (4) eine Mitnahmefläche (6) und eine Nockenfläche (8) aufweist,
    • eine Welle (10), die konzentrisch in Bezug auf das äußere Ringelement montiert ist, wobei die Welle eine Mehrzahl von Antriebselementen (12, 14) umfasst, die jeweils eine Mitnahmefläche (18, 20) und eine Nockenfläche (22, 24) aufweisen, wobei zwei der genannten Antriebselemente miteinander verbunden sind und einen Schieber (16) bilden, der im wesentlichen diametral über die Welle verläuft, wobei die genannten Antriebselemente so auf der Welle montiert sind, dass eine radiale Bewegung relativ zur Welle möglich ist, sodass:
    • eine Rotation der Welle oder des äußeren Ringelementes in seiner Mitnahmerichtung ein Eingreifen einer Mitnahmefläche (18, 20) von wenigstens einem Antriebselement (12, 14) in eine Mitnahmefläche (6) von wenigstens einem Zahn (4) bewirkt, wodurch sich eine gemeinsame Rotation der Welle und des äußeren Ringelementes ergibt, und
    • eine Rotation der Welle oder des äußeren Ringelementes in der der Mitnahmerichtung entgegengesetzten Richtung einen Eingriff der Nockenfläche (22, 24) von wenigstens einem Antriebselement (12, 14) in die Nockenfläche (8) von wenigstens einem Zahn bewirkt, was eine zusätzliche relative, im wesentlichen radiale, Bewegung zwischen dem genannten Antriebselement und dem genannten Zahn ergibt, wodurch verhindert wird, dass eine Drehbewegung zwischen der genannten Welle und dem genannten äußeren Ringelement übertragen wird,

      wobei der genannte Eingriff der Mitnahmeflächen in die Nockenflächen keine Federvorspannmittel erfordert.
  2. Inhaliergerät nach Anspruch 1, bei dem der Schieber in einem Kanal (26) in der Welle gehalten wird.
  3. Inhaliergerät nach Anspruch 1 oder Anspruch 2, bei dem das äußere Ringelement wenigstens acht feste, radial nach innen vorstehende Zähne umfasst.
  4. Inhaliergerät nach einem der vorherigen Ansprüche, bei dem der Schieber bis zu seinen äußersten Radialpositionen bistabil ist.
  5. Inhaliergerät nach einem der vorherigen Ansprüche, bei dem das Fortbewegungsmittel vollkommen aus Kunststoff hergestellt ist.
  6. Inhaliergerät nach Anspruch 5, bei dem der Kunststoff Polyacetal ist.
Anspruch[en]
  1. An inhaler having an elongate carrier bearing powdered medicament and an advancement means for moving the carrier to position an area of the carrier in a predetermined place for dispensing medicament, characterised in that the advancement means comprises a device for the transmission of one-way torque comprising:
    • an outer annular member (2) having a plurality of radially inwardly projecting teeth (4), each tooth (4) comprising a driving surface (6) and a cam surface (8),
    • a shaft (10) concentrically mounted with respect to the outer annular member, the shaft comprising a plurality of drive elements (12, 14) each having a driving surface (18, 20) and a cam surface (22, 24) two of said drive elements being interconnected to form a slider (16) extending substantially diametrically across the shaft, said drive elements being mounted on the shaft in a manner allowing radial movement relative to the shaft, whereby:
    • rotation of the shaft or outer annular member in its driving direction causes engagement of a driving surface (18, 20) of at least one drive element (12, 14) with a driving surface (6) of at least one tooth (4) thereby resulting in joint rotation of the shaft and outer annular member, and
    • rotation of the shaft or outer annular member in its non-driving direction causes engagement of the cam surface (22, 24) of at least one drive element (12, 14) with the cam surface (8) of at least one tooth resulting in additional relative movement, substantially radially, between said drive element and said tooth thereby preventing rotational movement being transmitted between said shaft and said outer annular member,
    • said engagement of the driving surfaces and the cam surfaces not requiring the presence of spring biasing means.
  2. An inhaler as claimed in Claim 1 in which the slider is retained within a channel (26) in the shaft.
  3. An inhaler as claimed in Claim 1 or Claim 2 in which the outer annular member comprises at least 8 fixed, radially inwardly projecting teeth.
  4. An inhaler as claimed in any preceding claim in which the slider is bistable to its extreme radial positions.
  5. An inhaler as claimed in any preceding claim in which the advancement means is completely constructed of plastics material.
  6. An inhaler as claimed in Claim 5 in which the plastics material is polyacetal.
Anspruch[fr]
  1. Un inhalateur ayant un support allongé qui supporte un médicament en poudre et des moyens d'avancement pour positionner une zone du support en un endroit prédéterminé pour la distribution du médicament, caractérisé en ce que les moyens d'avancement englobent un dispositif de transmission d'un couple unidirectionnel comportant :
    • un élément annulaire extérieur (2) ayant une pluralité de dents (4) qui font saillie radialement vers l'intérieur, chaque dent (4) englobant une surface d'attaque (6) et une surface de came (8),
    • un axe (10) monté concentriquement relativement à l'élément annulaire extérieur, l'axe englobant une pluralité d'éléments d'entraînement (12, 14) ayant chacun une surface d'attaque (18, 20) et une surface de came (22, 24), deux desdits éléments d'attaque étant interconnectés pour former une coulisse (16) qui s'étend sensiblement diamétralement en travers de l'axe, lesdits éléments d'entraînement étant montés sur l'axe d'une manière qui rend possible le mouvement radial relativement à l'axe, de façon telle que :
    • la rotation de l'axe ou de l'élément annulaire extérieur dans sa direction d'attaque fait mettre en prise une surface d'attaque (18, 20) d'au moins un élément d'attaque (12, 14) avec une surface d'attaque (6) d'au moins une dent (4), ce qui produit la rotation conjointe de l'axe et de l'élément annulaire extérieur, et
    • rotation de l'arbre ou de l'élément annulaire extérieur dans sa direction non d'attaque qui provoque la mise en prise de la surface de came (22, 24) d'au moins un élément d'attaque (12, 14) avec la surface de came (8) d'au moins une dent, ce qui produit un mouvement relatif supplémentaire, en sens sensiblement radial, entre ledit élément d'attaque et ladite dent, empêchant ainsi la transmission du mouvement de rotation entre ledit axe et ledit élément annulaire extérieur,
    • ladite mise en prise des surfaces d'attaque et des surfaces de came n'exigeant pas la présence de moyens de rappel par ressort.
  2. Un inhalateur selon la Revendication 1, dans lequel la coulisse est retenue à l'intérieur d'une rainure (26) dans l'axe.
  3. Un inhalateur selon la Revendication 1 ou la Revendication 2, dans lequel l'élément annulaire extérieur englobe au moins 8 dents fixes, qui font saillie radialement vers l'intérieur.
  4. Un inhalateur selon l'une quelconque des revendications précédentes, dans lequel la coulisse est bistable jusqu'à ses positions radiales extrêmes.
  5. Un inhalateur selon l'une quelconque des revendications précédentes, dans lequel les moyens d'avancement sont entièrement réalisés en une matière plastique.
  6. Un inhalateur selon la Revendication 5, dans lequel la matière plastique est le polyacétal.






IPC
A Täglicher Lebensbedarf
B Arbeitsverfahren; Transportieren
C Chemie; Hüttenwesen
D Textilien; Papier
E Bauwesen; Erdbohren; Bergbau
F Maschinenbau; Beleuchtung; Heizung; Waffen; Sprengen
G Physik
H Elektrotechnik

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