Injection device

An injection device has a housing and a metering member held rotatably in the housing and fixed in the direction of a longitudinal central axis. The metering member via a threaded connection is connected to a sleeve held rotationally fixed in relation to the housing and displaceable in the direction of the axis. When setting a dosage, the metering member rotates relative to the housing, and the sleeve moves distally. When dispensing a set dosage, the sleeve moves in the proximal direction, and the metering member by virtue of the threaded connection rotates in the opposite direction. To enable an automatic injection, the device has a spring supported in relation to the injection sleeve via a first end and in relation to the housing via a second end; the spring, when squeezing out liquid, moves the sleeve proximally and on account thereof causes the set dosage to be dispensed.

BACKGROUND OF THE INVENTION

An injection device of the generic type is known from WO 2013/117332 A1. The injection device has a metering member which, when setting a dosage of injection liquid to be squeezed out, is rotated in relation to the housing. An injection sleeve by way of a first threaded connection moves in the distal direction. The injection sleeve herein moves in the distal direction out of the housing. The operating button that is mounted on the injection sleeve moves conjointly with the injection sleeve in the distal direction. The operator, when squeezing out a set dosage of injection liquid, pushes the operating element in the proximal direction and, on account thereof, displaces the injection sleeve in the proximal direction. On account thereof, the metering member by virtue of the first threaded connection rotates in the opposite direction in relation to the housing, causing the injection liquid to be squeezed out from a container.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an injection device, in which the injection is performed automatically.

This object can, for example, be achieved by an injection device having: a housing defining a longitudinal central axis; a metering member held in the housing so as to be rotatable and fixed in the direction of the longitudinal central axis; an injection sleeve held so as to be rotationally fixed in relation to the housing and displaceable in the direction of the longitudinal central axis; the metering member being connected to the injection sleeve via a first threaded connection; the injection device defining a distal direction and a proximal direction; wherein the metering member, when setting a dosage of injection liquid to be squeezed out, rotates in relation to the housing and the injection sleeve by virtue of the first threaded connection moves in the distal direction; wherein the metering member, when squeezing out a set dosage of injection liquid, rotates in the opposite direction in relation to the housing and the injection sleeve by virtue of the first threaded connection moves in the proximal direction; a spring having a first end and a second end; the spring being supported via the first end in relation to the injection sleeve and via the second end in relation to the housing; and, wherein the spring, when squeezing out injection liquid, moves the injection sleeve in the proximal direction and on account thereof causes the set dosage of injection liquid to be squeezed out.

It is provided that the injection device has a spring which by way of a first end is supported in relation to the injection sleeve and by way of a second end is supported in relation to the housing. Accordingly, the spring acts between two components that, when setting a dosage of injection liquid to be squeezed out or pressed out, are moved in relation to one another in the direction of the longitudinal central axis. It is provided that the spring, when squeezing out injection liquid, moves the injection sleeve in the proximal direction, on account thereof causing the set dosage of injection liquid to be squeezed out from a container. The threaded connection of the injection sleeve can be conceived such that the injection sleeve has to travel a comparatively great axial distance, and a sufficiently large tensioning distance for tensioning the spring can be guaranteed.

The distance by which the injection sleeve moves in the axial direction is capable of being set by way of the conception of the first threaded connection such that an adaptation to the desired tensioning distance is enabled in a simple manner.

The spring is advantageously configured as a compression spring. The spring herein is in particular a compression coil spring. A configuration of the spring as a tension spring, in particular as a tension coil spring, can however also be advantageous. A simple construction results when the spring by way of the first end thereof is supported directly on the injection sleeve, and by way of the second end thereof is supported on the housing. The spring accordingly acts directly between the injection sleeve and the housing. However, it can also be advantageous for the spring to be supported on a component that is connected to the injection sleeve and/or to the housing.

A compact construction is achieved when the metering member is disposed radially within the injection sleeve. The spring is advantageously disposed on the external circumference of the metering member and at least partially in an annular space that is formed between the metering member and the injection sleeve.

In order for a set dosage to be read in a simple manner, it is provided that the housing has a viewing window, and that the injection sleeve has an opening which superposes the viewing window and through which a scale that is disposed on the external circumference of the metering member is visible. In order for an unequivocal display of the set dosage to be achieved even in the case of a large axial distance of the injection device and of a plurality of revolutions of the metering member up to the maximum dosage that can be set, it is provided that the injection sleeve has a portion which at the maximum dosage set covers the proximal region of the viewing window. In order to achieve a small construction length of the injection device, it is advantageously provided that the portion which covers the proximal region of the viewing window is configured on a web of the injection sleeve which protrudes in the proximal direction. The web herein advantageously extends only in the region of the viewing window, thus not across the entire circumference of the injection device. It is provided that the injection device comprises a container having an injection liquid. In the zero position of the injection device, thus when no quantity of injection liquid to be squeezed out or pressed out has been set, the web advantageously protrudes into the region of the container. A pocket into which the web in the zero position protrudes is advantageously formed in the radial direction between the container and an upper housing part of the injection device. On account of the web and the container mutually overlapping in the axial direction, a comparatively minor construction length of the injection device can be achieved.

The housing advantageously has a housing wall on which a pivot bearing for the metering member is configured. The housing wall advantageously runs so as to be approximately perpendicular to the longitudinal central axis. The web in the zero position advantageously protrudes through a passage opening in the housing wall onto the proximal side of the housing wall. The container is advantageously disposed, and the pocket for the web is advantageously configured, on the proximal side of the housing wall.

It is provided that the injection sleeve in each position of the injection device is disposed completely in the housing of the injection device. A movement of the injection sleeve in the distal direction out of the housing is advantageously not provided.

The injection device advantageously has an operating element which, when setting the dosage of injection liquid to be squeezed out, by way of a first coupling is connected in a rotationally fixed manner to the metering member and, when squeezing out a set dosage of injection liquid, by way of a second coupling is connected in a rotationally fixed manner to the housing and is rotatable in relation to the metering member. The operating element, when setting the dosage, is advantageously in a distal terminal position. The operating element, when setting the dosage, is accordingly not moved conjointly with the injection sleeve in the distal direction. In order for the first coupling to be released, the operating element is advantageously to be moved in the proximal direction. Releasing the first coupling herein corresponds to releasing the injection, since the metering member in the case of the released first coupling is rotatable in relation to the operating element and thus in relation to the housing, the spring being able to move the injection sleeve in the proximal direction and herein to rotate the metering member.

A metering piston which by way of a second threaded connection is connected to the metering member is advantageously provided for squeezing out injection liquid from the container. The metering piston, when setting the quantity of injection liquid to be squeezed out, is advantageously connected in a rotationally fixed manner to the metering member and rotates conjointly with the metering member. The metering piston, when squeezing out a quantity of injection liquid to be squeezed out, is advantageously connected in a rotationally fixed manner to the housing and by virtue of the second threaded connection moves in the proximal direction. A simple construction of the injection device is achieved on account thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1shows an injection device1as an embodiment of a mechanical injection device in which the squeezing out of a dosage of injection liquid is performed automatically. The injection device1has a housing2which comprises an upper housing part3and a holder4which is secured on an upper housing part3. The holder4is disposed on the proximal side of the upper housing part3. An injection needle8is secured on the proximal side of the holder4. An operating element6is disposed on the distal side of the injection device1. The operating element6by way of a coupling20is connectable in a rotationally fixed manner to the upper housing part3. The upper housing part3has a viewing window7which is advantageously composed of a transparent material such that an injection sleeve17that is disposed in the upper housing part3is visible through the viewing window7. The injection device1has a longitudinal central axis50which runs in the longitudinal direction of the housing2of the injection device1.

The distal end of the injection device1is that end that faces away from an injection needle8that is held on the injection device1. “Proximal” refers to that side of the injection device1which in an injection faces the pierced location, and “distal” refers to that side that faces away from the pierced location. The proximal direction describes the injection direction, thus the direction toward the injection needle8, or the direction in which the injection liquid is squeezed out from a container, respectively. The distal direction describes the opposite direction, thus away from the injection needle8.

FIGS. 1 and 2show the injection device1in a zero position28at which no dosage of injection liquid is set. The operating element6is in the distal terminal position90thereof. As is shown inFIG. 2, a container5having an injection liquid is disposed in the holder4. A plug10is disposed in the container5, a piston disk13of a metering piston11bearing on the plug10. The metering piston11moreover comprises a piston rod12which supports an external thread72.

The external side of the injection sleeve17is visible through the viewing window7of the upper housing part3. The injection sleeve17has an opening26through which the external circumference of a metering member18that is disposed radially within the injection sleeve17is visible. The metering member18which can also be referred to as a graduated tube, on the external circumference thereof supports a scale59(shown inFIG. 30) which is visible to the operator through the viewing window7and through the opening26, and displays the set dosage of injection liquid to be squeezed out.

The injection sleeve17is held in the upper housing part3so as to be displaceable in the direction of the longitudinal central axis50and so as to be rotationally fixed in relation to the upper housing part3. The injection sleeve17herein is disposed completely within the housing2, specifically within the upper housing part3, in each position of the injection device1. The metering member18and the injection sleeve17are interconnected by way of a first threaded connection19. The metering member18is mounted on a pivot bearing21so as to be rotatable in the upper housing part3, and held so as to be axially non-displaceable in the upper housing part3. The metering member18by way of a second threaded connection22is connected to the external thread72of the piston rod12.

An entrainment element14is mounted in the upper housing part3. The entrainment element14is connected in a rotationally fixed manner to the metering member18by way of a rotationally fixed connection24. The rotationally fixed connection24can be a press-fit connection. However, it can also be provided that the rotationally fixed connection24is a form-fitting connection. The entrainment element14is rotatably mounted on a pivot bearing15that is configured in an upper housing part3. The pivot bearing15is formed by a periphery of the upper housing part3.

As is also shown inFIG. 2, a spring9which is configured as a compression spring, specifically as a compression coil spring, is disposed in the upper housing part3. The spring9by way of a first end70is supported on a bearing periphery27of the injection sleeve17, and by way of a second end71is supported on a bearing periphery25of the upper housing part3. The pivot bearing15for the entrainment element14is also configured on the bearing periphery25. The spring9is disposed so as to be radially outside the metering member18, and in the zero position28shown inFIG. 2, by way of the proximal region of the spring9, protrudes into an annular space64that is formed between the injection sleeve17and the metering member18.

The operating element6is connected in a rotationally fixed manner to the piston rod12by way of a connection element56which is configured as a sleeve. The operating element6is supported in relation to the upper housing part3by way of a spring23which is configured as a compression coil spring. The spring23, which pushes the operating element6in the distal direction, has no influence on the injection rate. The spring23is conceived merely such that the operator can activate the operating element6by way of a comfortable force. A shoulder32which, in the case of an operating element6that is pushed in the proximal direction, interacts with a periphery33of the upper housing part3is configured on the operating element6, the shoulder32conjointly with the periphery33forming a detent which delimits the proximal position of the operating element6. A further detent which can be configured on the entrainment element14, for example, is advantageously provided for establishing the distal terminal position90of the operating element6. A latching installation35which comprises a plurality of latching arms36, one of which being visible inFIG. 2, acts between the operating element6and the upper housing part3. The operating element6in the zero position28shown inFIGS. 1 and 2is coupled in a rotationally fixed manner to the entrainment element14by way of a coupling16. Moreover, a setting device41which comprises a multiplicity of latching depressions44in the entrainment element14is formed between the operating element6and the entrainment element14.

In the case of a non-activated operating element6, the spring23pushes the operating element6to the distal terminal position90thereof, in which the coupling20is opened and the operating element6is rotatable in relation to the housing2. In order to set a quantity of injection liquid to be squeezed out, the operator rotates the operating element6about the longitudinal central axis50. The entrainment element14that by way of the coupling16is connected in a rotationally fixed manner to the operating element6is conjointly rotated herein. The entrainment element14by way of the rotationally fixed connection24is connected to the metering member18which is likewise conjointly rotated. The piston rod12by way of the connection element56is connected in a rotationally fixed manner to the operating element6and is likewise conjointly rotated. The injection sleeve17, by virtue of the first threaded connection19and of the fixing of the injection sleeve17in a rotationally fixed manner in the upper housing part3, is moved in the distal direction30in the rotating movement of the metering member18. The injection sleeve17, by way of the bearing periphery27thereof, herein moves toward the bearing periphery25of the spring9, on account of which the spring9is tensioned. The bearing periphery25of the housing2herein can form a detent for the distal position of the injection sleeve17, thus also for the maximum dosage that can be set. The axial position of the operating element6is not changed when the dosage of injection liquid to be squeezed out is set. The length of the annular space64has been shortened by virtue of the movement of the injection sleeve17in the distal direction.

FIGS. 3 and 4show the injection device1in a maximum position29at which the maximum dosage is set. The length of the spring9has been shortened from the non-tensioned length a, shown inFIG. 2, to the tensioned length b, shown inFIG. 4. It can also be provided that the spring9is pretensioned also in the zero position28. The injection sleeve17can bear on the bearing periphery25. The spring9in the maximum position29in the embodiment is disposed completely in the annular space64. As is shown inFIG. 3, the maximum dosage is visible through the viewing window7in the maximum position29. The injection sleeve17has a web34which protrudes in the proximal direction and covers the region of the metering member18that is visible through the viewing window7and that does not display the set dosage. A pocket92into which the web34in the zero position28protrudes is formed in the radial direction between the container5and the upper housing part3. The web34herein protrudes through a housing wall87of the upper housing part3onto the proximal side of the housing wall87. The pivot bearing21for the metering member18is configured on the housing wall87. The threaded connection22between the piston rod12and the metering member18is also disposed in the region of the housing wall87.

In order for a set quantity of injection liquid to be squeezed out, the operator pushes the operating element6in the proximal direction31. On account thereof, webs38of the coupling20(FIG. 1) come to engage with latching elements85of the latching installation35(FIG. 38). On account thereof, the operating element6in relation to the upper housing part3is fixed in a rotationally fixed manner. At the same time, the coupling16by virtue of the axial relative movement of the operating element6in relation to the entrainment element14is at least partially released such that the entrainment element14, conjointly with the metering member18, can rotate about the longitudinal central axis50. The rotating movement is performed by virtue of the axial force that is exerted by the tensioned spring9on the injection sleeve17, the force causing a rotation of the metering member18. The rotation is performed by virtue of the threaded connection19and of the injection sleeve17being guided in a rotationally fixed manner in the housing part3. The piston rod12is connected in a rotationally fixed manner to the upper housing part3by way of the connection element56and of the operating element6. Therefore, the second threaded connection22in the rotation of the metering member18causes a movement of the piston rod12in the proximal direction31. On account thereof, the set quantity of injection liquid is squeezed out from the container5.

By virtue of the force stored in the spring9, the injection is performed automatically upon releasing the coupling16. The spring9is conceived such that the force stored in the spring9is sufficient in order for the resistance of the plug10to be overcome and for injection liquid to be squeezed out from the container5. The injection device1has the setting device41in order for the injection rate to be set. The setting device41influences the torque that is required for rotating the entrainment element14in relation to the operating element6. The torque required herein depends on the axial position of the operating element6in relation to the upper housing part3and to the entrainment element14. This will be explained in yet more detail hereunder.

FIGS. 5 to 11show the construction of the operating element6in detail. The operating element6has an operating portion55which protrudes from the upper housing part3, the operator being able to rotate the operating element6or to displace the latter in the proximal direction31at the operating portion55. The operating element6has a sleeve portion49(shown inFIGS. 5 and 6) which in the zero position28and the maximum position29protrudes partially from the upper housing part3, the webs38of the coupling20being fixed to the sleeve portion49. The sleeve portion49on the proximal end thereof supports a total of three latching arms36which at the free end thereof have in each case one latching element47.

This is also shown inFIG. 8. The outwardly protruding latching elements47by way of the latching arms36are mounted so as to be movable in a radially inward manner.

As is also shown inFIG. 5, the operating element6has a connector66which on the external circumference thereof supports two bevels67for connecting in a rotationally fixed manner to the connection element56. As is shown inFIGS. 17 and 18, the connection element56, which is configured so as to be sleeve-shaped, on the internal side thereof has corresponding bevels58which interact with the bevels67of the connector66and, on account thereof, interconnect in a rotationally fixed manner the operating element6and the connection element56. As is shown inFIGS. 19 and 20, the piston rod12on a distal end portion73supports corresponding bevels74in order for the piston rod12and the connection element56to be connected in a rotationally fixed manner. The external thread72of the piston rod12is also shown inFIGS. 19 and 21.

As is shown inFIGS. 5 and 8, the operating element6in the embodiment has six latching webs43which in relation to the longitudinal central axis50protrude in a radially outward manner and which conjointly with the latching depressions44of the entrainment element14form a latching installation42(FIG. 25). As is schematically shown inFIG. 9, each latching web43has a radially outward latching edge45. The latching edges45in the embodiment are inclined in relation to the longitudinal central axis50by an angle α. The angle α is adapted to the desired activation distance between the slowest and the fastest injection rate that can be set, and to the desired difference between the slowest and the fastest injection rate. As is schematically shown inFIG. 9, the latching webs43are disposed on a pin portion48of the operating element6, the pin portion48running within the sleeve portion49at a radial spacing from the sleeve portion49. The connector66adjoins the pin portion48at the proximal end. The latching webs43in the embodiment are configured so as to be integral to the operating element6and are composed of the same material as the operating element6. However, it can also be advantageous for the latching webs43to be configured from another material, for example from an elastomer or a rubber, in order for a desired latching characteristic to be set.

As is shown inFIGS. 10 and 11, the operating element6is constructed from a first individual part39and from a second individual part40, in order for the production and the assembly to be simplified. The operating element6can also be formed from a larger number of individual parts. The individual parts39and40in the embodiment are fixedly interconnected at a latching periphery37of the first individual part39.

FIGS. 12 to 16show the configuration of the entrainment element14in detail. The entrainment element14has a bearing portion57having a reduced diameter, by way of which the entrainment element14is rotatably mounted in the upper housing part3. As is shown inFIG. 13, the entrainment element14in the interior thereof has a conical portion61which is disposed in a proximal region, a cylindrical portion62adjoining the conical portion61on the distal side of the latter. The conical portion61and the cylindrical portion62are formed by a multiplicity of webs63(shown inFIGS. 14 to 16) which protrude in a radially inward manner from a cylindrical external wall68of the entrainment element14. The latching depressions44are formed in the circumferential direction between the webs63. The webs63have radially inward counter latching edges46which are inclined in relation to the longitudinal central axis50by an angle β. The angle β herein is open toward the proximal direction. In particular, the angle β is the same size as the angle α of the latching edges45of the latching webs43.

The webs63in the cylindrical portion62delimit an interior space60, the interior diameter h of the latter (shown inFIG. 14) being only slightly larger than the external diameter of the pin portion48. The webs63in the cylindrical portion62have a radially measured height f1that corresponds to approximately the radial extent of the latching webs43.

FIG. 15shows a section through the conical portion61. The radially inward latching edges46of the webs63in the section plane shown inFIG. 15have a spacing g1from the longitudinal central axis50. The radially measured height f2of the webs63in the section plane through the conical portion61shown inFIG. 15is significantly smaller than the height f1in the cylindrical portion62.

FIG. 16shows a section through the conical portion61, adjacent to the proximal end of the interior space60. The latching edges46in this section plane have a spacing g2from the longitudinal central axis50which is significantly larger than the spacing g1. The radially measured height f3of the webs63in the section plane through the conical portion61shown inFIG. 15is significantly smaller than the height f2in the distal section plane shown inFIG. 15.

FIGS. 22 to 29show the operating element6and the entrainment element14in different axial relative positions.FIGS. 22 and 23show the operating element6and the entrainment element14in a coupling position51. In this position, the operating element6and the entrainment element14are interconnected in a rotationally fixed manner by way of the coupling16. The coupling16is formed by the webs63in the cylindrical portion62. The webs63protrude up close to the pin portion48and overlap the latching webs43on the distal side thereof in the circumferential direction by an engagement depth o. The engagement depth o is chosen such that the entrainment element14and the operating element6are interconnected in a rotationally fixed manner.FIGS. 23, 25, 27, and29herein show sections through the operating element6on the distal side of the latching webs43. The sleeve portion49has a proximal end side65. The proximal end side65in the coupling position51has a first spacing n1, measured from a lower edge86of the entrainment element14in the direction of the longitudinal central axis50. The lower edge86herein is that edge of the entrainment element14that bears on the inwardly protruding periphery of the upper housing part3.

FIGS. 24 and 25show the operating element6and the entrainment element14in a first relative position52, at which the setting device41acts between the operating element6and the entrainment element14. The proximal end side65of the sleeve portion49has a spacing n2from the lower edge86of the entrainment element14which is smaller than the spacing n1. As is shown inFIG. 25, the latching webs43are in the conical portion61in which the spacing of the latching edges46of the webs63from the pin portion48and from the longitudinal central axis50is reduced. In this relative position, the latching webs43, on the distal side of the latching webs43, overlap the webs63in the radial direction by a latching depth m1. The latching depth m1is significantly smaller than the engagement depth o in the coupling position51. The latching depth m1is chosen such that the entrainment element14can rotate in relation to the operating element6while deforming the latching webs43.

In order to reach the first relative position52from the coupling position51, the operator has to move the operating element6in the proximal direction31, as is indicated inFIG. 24. On account thereof, the operating element6is displaced relative to the upper housing part3, and the webs38on the operating element6come to engage with a latching mechanism84(shown inFIGS. 36 and 38) on the internal side of the upper housing part3. The latching mechanism84has a multiplicity of latching elements85which secure the operating element6in a rotationally fixed manner in relation to the external housing part3. The webs38, conjointly with the latching mechanism84, form the coupling20.

In the case of the first relative position52, shown inFIGS. 24 and 25, the entrainment element14can rotate relative to the upper housing part3and relative to the operating element6when the energy stored in the spring9is sufficient in order for the latching webs43to be deformed and for the plug10to slide in the proximal direction such that the injection liquid is squeezed out from the container5. However, by virtue of the high torque that is required for rotating the entrainment element14in relation to the operating element6, the squeezing out of injection liquid is performed very slowly.

In the second relative position53, shown inFIGS. 26 and 27, of the operating element6and of the entrainment element14, the operator has pushed the operating element6in the proximal direction31further into the upper housing part3. The proximal end side65in this position has a third spacing m3from the lower edge86of the entrainment element14. The third spacing m3is significantly smaller than the second spacing m2. In the movement of the operating element6in the proximal direction31the latching webs43in the conical portion61have moved further in the proximal direction, thus in the direction toward an enlarged internal diameter of the conical portion61. The distal side of the latching webs43in the radial direction toward the longitudinal central axis50has a minor overlap in relation to the webs63, such that only a minor latching depth m2results. In this position of the setting device41, the torque required for rotating the entrainment element14in relation to the operating element6is significantly smaller than in the case of the first relative position52shown inFIGS. 24 and 25. The latching webs43have to be only slightly deformed in order for the webs63to be overcome and for the next latching position to be reached. On account thereof, an injection at the second relative position shown inFIGS. 26 and 27is performed at a higher rate than in the case of the first relative position shown inFIGS. 24 and 25.

FIGS. 28 and 29show the operating element6and the entrainment element14in a third relative position54in which the lower edge86has only a very minor fourth spacing n, from the proximal end side65. The operating element6is in the proximal terminal position thereof in the third relative position54, in which the shoulder32(shown inFIG. 2) bears on the periphery33of the upper housing part3. As is shown inFIG. 29, the latching webs43in the third relative position54in the radial direction have an extremely minor overlap in relation to the webs63. The latching depth m3is minimal. It can also be provided that the latching depth m3is zero, such that the latching webs43can freely rotate in relation to the webs63, and the setting device41in the third relative position54does not slow down the rotation of the entrainment element14in relation to the operating element6. Therefore, the highest possible injection rate results in the third relative position54. The energy which is required for rotating the entrainment element14in relation to the operating element6is minor. The injection rate is determined by the force stored in the spring9and by the friction forces which act between the mutually moving components.

The angle α of the latching edge45of the latching web43and the angle β of the latching edge46of the web63are identical in the embodiment. On account thereof, the latching depths m1, m2, m3are the same across the entire height c of the latching webs43. In the case of dissimilar angles α, β, dissimilar latching depths m result in different portions of the latching web43. The force exerted by the setting device41can be influenced by a suitable choice in terms of the configuration and the number of the latching webs43.

FIGS. 30 and 31show the metering member18in detail. The metering member18has an external thread75which, conjointly with an internal thread80of the injection sleeve17(shown inFIG. 34), forms the first threaded connection19. The metering member18has a bearing connector69by way of which the metering member18is rotatably mounted in a bearing opening82in the upper housing part3(FIGS. 36 and 37). The metering member18has bearing webs76which bear on that distal side of the housing wall87that has the bearing opening82. The friction between the metering member18and the upper housing part3in the rotating movement of the metering member18is reduced. As is shown inFIG. 31, an internal thread77which, conjointly with the external thread72of the piston rod12, forms the second threaded connection22is configured in the bearing connector69(FIG. 2).

As is shown inFIG. 32, the injection sleeve17has clearances78which serve for reducing the weight. The opening26behind which the scale59of the metering member18(FIG. 30) is visible to the operator is also shown inFIGS. 32 to 34.

The injection sleeve17on the external circumference thereof has two guide grooves79which are disposed so as to be mutually opposite. Corresponding guide webs81, one of which being visible inFIG. 36, are configured in the upper housing part3. The guide webs81protrude into the guide grooves79and, on account thereof, guide in a rotationally fixed manner the injection sleeve17in the upper housing part3so as to be movable in the direction of the longitudinal axis50.

As is shown inFIG. 37, the housing wall87beside the bearing opening82has a passage opening83, the web34of the injection sleeve17protruding through the latter. The web34does not extend across the entire circumference of the injection sleeve17but only across the circumferential region in which the viewing window7is disposed. On account of the web34, a small construction length of the injection device1is achieved at a sufficiently large adjustment range of the metering member18. The metering member18rotates and the injection sleeve17is displaced in the axial direction when the dosage is being set. On account thereof, the set dosage is in each case visible through the opening26.

As is shown inFIG. 38, the latching elements85of the latching mechanism84in the embodiment are configured so as to be non-symmetrical. The latching elements85interact with the latching elements47on the operating element6(FIG. 5). A dosage once set cannot be reduced by virtue of the non-symmetrical configuration of the latching elements. However, a reverse rotation of the operating element6for reducing a set dosage can also be possible by way of a corresponding configuration of the latching elements85and of the latching elements47.

Clicking noises on account of the latching elements47and85are audible when setting a quantity of injection liquid to be squeezed out. As the operating element6and the upper housing part3are interconnected in a rotationally fixed manner when a quantity of injection liquid is being squeezed out, the clicking noises of the latching installation35are not audible when squeezing out injection liquid. Instead, clicking noises of the latching installation42of the setting device41are audible to the operator when squeezing out injection liquid. The latching installation42in the first latching position52herein generates louder clicking noises at a larger temporal interval. The further the operating element6is pushed in the proximal direction31, the quieter the clicking noises and the more rapid the succession of the clicking noises. On account thereof, the injection rate is audible to the operator. The latching elements85, conjointly with the latching elements47, form the latching installation35when setting the dosage of injection liquid to be squeezed out. In the squeezing out of injection liquid, the latching elements85interact with the webs38and, conjointly with the latter, form the coupling20and connect the operating element6in a rotationally fixed manner to the upper housing part3.

FIGS. 39 to 54show an embodiment of an injection device101, the construction of the latter corresponding substantially to that of the injection device1from the preceding figures. Equivalent components are identified by the same reference signs in all figures. The injection device101has a housing2having a viewing window7through which the injection sleeve17is visible. The injection device101has an operating element106that in the zero position28shown inFIGS. 39 and 40is in a distal terminal position90. The operating element6in this position can be held, for example, by a detent (not shown) that is configured on an entrainment element114.

As is shown inFIG. 40, the injection device101differs from the injection device1substantially in terms of the configuration of the operating element106and of the entrainment element114. The operating element106is pretensioned in the distal terminal position90thereof by a spring23. A detent which is formed by a shoulder32of the operating element106and by a periphery33of the upper housing part3is formed between the operating element106and the upper housing part3. A latching installation35acts between the operating element106and the upper housing part3. The entrainment element114is mounted in the upper housing part3by way of a pivot bearing15. A coupling116which in the distal terminal position90shown of the operating element106connects the operating element106in a rotationally fixed manner to the entrainment element114is formed between the entrainment element114and the operating element106.

FIGS. 41 to 43show the configuration of the operating element106and of the entrainment element114in detail. As is shown inFIG. 42, the upper housing part3in the distal end region thereof has a latching mechanism84which is formed by a multiplicity of latching elements85. When setting a quantity of injection liquid to be squeezed out, the operating element106is to be rotated in a first rotation direction88in relation to the upper housing part3. The latching elements47herein latch into the latching elements85of the upper housing part3. Clicking noises that are audible to the operator are created herein. The entrainment element114has receptacles117which are configured as radially aligned slots, coupling webs104of the operating element106protruding into the receptacles117. The coupling webs104can be configured so as to correspond to the latching webs43of the injection device1. The coupling webs104, conjointly with the receptacles117, form the coupling116.

As is shown inFIGS. 41 and 43, an interior space110is formed on that proximal side of the portion of the entrainment element114that has the receptacles117, only the connector66of the operating element106protruding through the interior space110in the distal terminal position90shown of the operating element106.

The injection device101is shown in a terminal position102inFIGS. 44 and 45. Upon setting a quantity of injection liquid to be squeezed out by rotating the operating element106in the first rotation direction88, the operating element106was moved in the proximal direction31until the operating element106came to be in the proximal terminal position91thereof shown inFIGS. 44 and 45. The coupling116was released in the proximal movement of the operating element106, and the entrainment element114was released and was able to rotate conjointly with the metering member18about the longitudinal central axis50. The rotating movement was initiated by the energy which was stored in the spring9and which moved the injection sleeve17in the proximal direction31. The shoulder32of the operating element106in the proximal terminal position91of the operating element106bears on the periphery33of the upper housing part3and forms the detent for the proximal terminal position91. The coupling webs104of the operating element106are disposed in the interior space110of the entrainment element114. As is shown inFIGS. 46 and 48, the coupling webs104can freely rotate in the interior space110. Upon release of the coupling116, the entrainment element114, conjointly with the metering member18, was able to rotate in the second rotation direction89, and on account thereof was able to squeeze out the set dosage of injection liquid from the container5.

As is shown inFIG. 47, the webs38of the operating element106in the proximal terminal position91of the operating element106lie between the latching elements85, and on account thereof connect the operating element106in a rotationally fixed manner to the upper housing part3. The coupling webs104are not in the receptacles117but are completely in the interior space110such that a free rotation is possible. The webs38, conjointly with the latching elements85of the latching mechanism84, form the coupling20.

FIGS. 49 to 54show the configuration of the entrainment element114in detail. As is shown inFIG. 49, the receptacles117are configured as radially running slots. The entrainment element114has a bearing portion115by way of which the former is rotatably mounted in the housing wall87(FIG. 46). As is shown inFIGS. 49 and 50, the entrainment element114in a proximal end region has securing webs118which serve for the rotationally fixed connection to the metering member18. The entrainment element114is connected in a form-fitting manner to the metering member18by way of the securing webs118. The entrainment element114centrally has an opening120through which the connector66of the operating element106protrudes. As is shown inFIGS. 52 and 53, the entrainment element114has a coupling portion119in which the receptacles117of the coupling116are configured. In the interior space110that adjoins the coupling portion119on the proximal side, the available internal diameter is chosen to be so large that the coupling webs104(FIG. 46) can freely rotate in the interior space110.

In the case of the embodiment of an injection device101shown inFIGS. 39 to 54the injection rate is not selectable by the operator but is determined by the energy stored in the spring9, by the viscosity of the injection liquid, by the diameter of the injection needle, and by the friction of the plug10in relation to the container5. In contrast, in the case of the injection device1the injection rate can be selected by the operator by way of a respective positioning of the operating element6.