HK1135622B - Single-use injector with at least one draw hook - Google Patents

Description

Disposable syringe with at least one draw hook

Technical Field

The invention relates to a needle-free disposable injector having a housing, on or in which at least one mechanical spring energy store, at least one syringe/piston unit which can be filled with an active substance at least temporarily, at least one piston actuating plunger and at least one triggering unit are arranged in each case at least in certain regions, wherein the spring energy store comprises at least one pretensioned spring element, and wherein at least a part of the piston actuating plunger is positioned between the spring energy store and the piston of the syringe/piston unit.

Background

A syringe of this type is known in particular from european patent EP0710130B 1. The injector is designed in such a way that the individual components, namely the spring energy store, the syringe/piston unit and the trigger unit cannot be handled separately or individually from one another. The trigger unit has a latching mechanism in which a slider moving transversely to the centre line of the syringe locks or releases the piston-operating plunger via a cutout or a threaded groove.

An autoinjector for automatically injecting active substances is known from DE102004060146a1, comprising a longitudinal housing; an injection needle axially displaceable within the housing, said injection needle being connectable to an active substance container; a piston which is movable in the active substance container for dispensing the active substance; and a needle protection tube movable relative to the housing. Wherein a locking element prevents the active substance container from moving relative to the housing in the locked position. Furthermore, the locking element is brought into an open position by moving the needle protection tube into the housing, in which open position the active substance container is allowed to move relative to the housing.

An injection device is known from WO03/092771, comprising:

a housing for containing a syringe having a bore extending from an end face, a needle communicating with the bore through the end face, and an output or dosing piston which moves in the bore towards the end face to inject the contents of the syringe through the needle, wherein the housing has an opening at the end through which the needle can extend;

a spring element to pre-tension the syringe and needle towards the inside with respect to the housing;

a drive element movable towards one of its ends to move the needle of the syringe out of the housing and to move the output or dosing piston of the syringe towards the end face;

a mechanism operable to release the syringe to move the needle inwardly relative to the housing;

a drive clutch to extend from the drive element to an output or dosing piston of the syringe for transmitting movement of the drive element to the output or dosing piston, wherein the drive clutch is compressible over its length;

after the drive element has moved the output or dosing piston towards the end face, the drive clutch gradually reduces its length and drives a sufficient force to hold the needle in its extended position and the output or dosing piston on the end face until the mechanism releases the syringe.

Another embodiment of an injection device is known from WO2007/002052a2, which has a needle and a plurality of associated springs.

Disclosure of Invention

The object of the present invention is therefore to develop a needleless disposable injector of modular design which, with a small overall size, comprises only a small number of components and, with simple handling, ensures safe storage and functionality.

This object is achieved by the features of the independent claims. The spring-loaded piston-operated plunger therefore has at least one tension rod which can be moved transversely at least in some regions and which, by means of a bearing section, bears a tensioned spring energy store on at least one bearing surface of the housing. The triggering unit is or has at least one triggering element which, when operated, causes and releases a movement of the support section away from the support surface.

The invention provides a needle-free disposable syringe, the piston-actuating plunger of which performs a movement oriented transversely to the longitudinal direction and/or transversely to the center line of the disposable syringe during the triggering process of the disposable syringe. For this purpose, one or more parts of the piston actuating plunger are pressed against the housing or against a component arranged on the housing by means of at least one circumferential engagement or hook for pretensioning and retaining the spring energy store. If necessary, only certain elements and regions of the piston-operating plunger can be designed to be movable relative to the housing of the needle-free disposable syringe. To trigger a needle-free disposable syringe, the housing-side bearing surface surrounding the snap-fit or hook moves it downward so that the piston-operating plunger can be moved at least approximately parallel to the center line of the disposable syringe under the action of the spring energy store.

Drawings

Further details of the invention emerge from the dependent claims and the following description of several exemplary embodiments, in which:

FIG. 1: showing a single use syringe having a pull rod;

FIG. 2: as shown in fig. 1, but tripped and operated;

FIG. 3: as shown in fig. 2, but after ejection of the medicament;

FIG. 4: showing a single-use syringe having a plurality of pull rods;

FIG. 5: as shown in fig. 4, but tripped and operated;

FIG. 6: as shown in fig. 5, but after ejection of the medicament;

FIG. 7: a top view of the bottom of the disposable syringe according to fig. 4 is shown, but without the stepped trigger sleeve;

FIG. 8: showing a single-use syringe having a plurality of draw rods with inwardly directed draw hooks;

FIG. 9: as shown in fig. 8, but tripped and operated;

FIG. 10: as shown in fig. 9, but after ejection of the medicament;

FIG. 11: a top view of the fastening element of the disposable syringe according to fig. 8 is shown, but without the trigger element;

FIG. 12: showing a single-use syringe having a plurality of outwardly resiliently deformable pull rods;

FIG. 13: as shown in fig. 12, but tripped and operated;

FIG. 14: as shown in fig. 13, but after ejection of the medicament;

FIG. 15: a side view of the disposable syringe according to fig. 12 is shown, but before use;

FIG. 16: a side view of the disposable injector according to fig. 12 is shown, but without the syringe/piston unit and the support sleeve;

FIG. 17: showing a single-use syringe having a plurality of inwardly resiliently deformable pull rods;

FIG. 18: as shown in fig. 17, but tripped and operated;

FIG. 19: as shown in fig. 18, but after ejection of the medicament;

FIG. 20: the disposable syringe according to fig. 17 is shown in a side view, but before use.

Detailed Description

Fig. 1 to 3 show a simplified principle of a disposable syringe with a continuously pressurized spring energy store. The disposable syringe comprises: a housing 10; such as a filled syringe/plunger unit 100; a piston operating plunger 60 having a draw hook 62; and a helical compression spring 50 as a spring accumulator. Furthermore, a trigger unit 80 is arranged on a housing 10, in which a trigger element 82 and a fastening element 95 are arranged.

The housing 10 is a hollow body in the shape of a pot open at the bottom, having a base 32 at the top. The base 32 has, for example, an eccentric opening 34, through which opening 34 the pull hook 62 extends according to fig. 1. The holding portion 65 of the pull hook 62 rests on the holding surface 37 of the housing 10.

The piston operating plunger 60 is divided into three regions. The lower region is the piston slide 76. Which has a diameter slightly smaller than the inner diameter of the syringe 101 of the syringe/piston unit 100. The lower end face of the piston slide 76 acts directly on the piston 111.

The middle region is the plunger disc 73. The plunger disc 73 is a flat, at least partially cylindrical disc having an outer diameter which is a few tens of millimetres smaller than the inner diameter in the jacket region 31 of the housing 10. The upper region is the draw hook 62.

A syringe/piston unit 100 is fastened to the lower part of the housing 10. Here, the syringe/plunger unit 100 includes: a cartridge 101 is filled with an injection solution 1, in which a piston 111 is arranged in a rear position. Above the piston 111, a piston operating plunger 60 is provided in the housing 10, for example, such that: so that it, although not touching the piston, is guided laterally with its lower end in the upper region of the syringe 101.

The helical compression spring 50 is seated with pretension between the plunger disc 73 and the seat 32 at the top of the housing 10.

The trigger unit 80 is inserted on the housing 10. The triggering unit 80 has a sleeve 85 over the majority of its closed end wall, into which sleeve 85 a pin-shaped fastening element 95 is inserted. The fastening element 95 is positioned in combination with the housing 10 such that it holds the draw hook 62 on the edge 36 of the opening 34 adjacent the support surface 37. In the installed state, the fastening element 95 prevents an unintentional displacement of the draw hook 62 transversely to the longitudinal direction of the piston actuating ram 60.

For example, transversely to the center line 5 of the housing 10, a triggering element 82 is mounted in the triggering unit 80 so as to be longitudinally displaceable. To operate the disposable syringe, the fastening element 95 is pulled, as shown in fig. 2, to position the disposable syringe relative to the patient, and then the trigger element 82 is pressed, for example, by a finger of the hand carrying the disposable syringe. In the event of a slight tilting of the entire piston operating plunger 60, the triggering element 82 pushes the bearing section 65 away from the bearing surface 37. The sliding movement is performed transversely to the longitudinal axis or centerline 5 of the disposable syringe. Thereafter, the bearing section 65 slides through the opening 34 into the interior 11 of the housing 10 under the action of the helical compression spring 50. Referring to fig. 3, the syringe/piston unit 100 is emptied therein.

In this principle, the piston slide 76 can also be designed as a separate component. For this purpose, it is then guided on the inner wall of the housing 10. It is also possible to form the piston slide 76 as a piston rod integrally on the piston 111 and to guide the piston rod here only by means of the piston 111 and/or by means of a bearing, for example, in a partial region on the inner wall of the syringe 101. Of course, the piston slider 76 and the piston rod may arbitrarily partition the space between the plunger disc 73 and the piston 111.

The type of trigger is not limited to the variations described herein. Instead of the laterally displaceable triggering element 82, for example, a centrifugal gear, a helical gear or a lever gear can be used.

Fig. 4 to 6 show an improvement of the principle according to fig. 1 to 3. The piston actuating ram 60 has, for example, two structurally identical hooks 62 above the ram disk 73. The two hooks 62 are mirror-symmetrically opposite each other. The draw hook 62 is made of, for example, an elastic material. The two hooks 62 are back to back, wherein they are intended to be pressed apart in the manner of a spring so that they rest against the edge 36 of the opening 34, for example under pretension. Its spring direction is indicated by an alternative helical compression spring 64 located transversely therebetween.

Of course, it is also possible to use such a helical compression spring 64 in practice if, for example, the draw hook 62 is articulated on the plunger disc 73 by means of a swivel hinge. The pivot axis of the swivel hinge is then transverse to the housing centre line 5 and perpendicular to the view plane according to fig. 4 to 6.

In this variant, the support section 65 has a wedge-shaped or truncated-cone-shaped outer contour 66, by means of which support section 65 the respective pull hook 62 rests, for example, on the flat outer surface 33 of the base 32. The cross section of the bearing section 65 tapers upward along the center line 5. In fig. 4 to 6, the outer contour 66 is the part of a pyramid surface with a theoretical pyramid tip on the center line 5 above the base 32, see fig. 4, 5 and 7.

A pin-shaped fastening element 95 is inserted between the ends of the draw hooks 62, see also fig. 7. Here, it has, for example, a rectangular cross section. For example, a fastening element 95 mounted on the housing 81 of the trigger unit 80 mechanically locks the draw hook 62 in its locking position.

The trigger housing 81 is pot-shaped and is arranged longitudinally displaceably on the rear of the housing 10. A rectangular tube 86, for example, is mounted on the base of the trigger housing 81, while the fastening element 95 is guided. At the transition from the base to the rectangular tube 86, the latter has a beveled region 88. The ramp region 88 forms a wedge-shaped surface on the trigger housing side.

After the securing element 95 is removed, the trigger housing 81, such as a button, may be moved downward. Here, a wedge surface 88 on the housing side of the trigger rests against the respective catch 62 and presses them together counter to the action of a symbolically indicated compression spring 64, so that the bearing section 65 passes through the opening 34. The bearing section 65 forms a sliding wedge drive with the wedge surface 88 on the trigger housing side. If desired, the wedge surface 88 and/or the surface of the wedge-shaped outer contour 66 of the bearing section 65 may be uniaxially or multiaxially curved, for example cylindrical or spherical, so that a curved surface slides along a flat surface or the surface of another curved portion.

As a component of the piston actuating ram 60, for example, the draw hooks 62 in the form of elastic deformation, which, once they have reached the interior 11 of the housing 10, are again elastically deformed, for example, apart from one another.

Fig. 8 to 11 show a schematic variant in which the hooks 62 are arranged opposite one another, for example in pairs, i.e. the support sections 65 face one another. In this case, the hooks 62 are elastically deformed toward each other.

According to fig. 8, the housing 10 of this variant has two, for example rectangular, recesses 34 in the base 32, which are separated by a housing web 35. The housing web 35 is part of the base 32, on which housing web 35 the support section 65 of the draw hook 62 is supported in the locked position of the disposable syringe. In order to hold the hooks 62 firmly on the housing web 35, they engage partially around the housing base 32. For this purpose, a fastening element 95 is used, see also fig. 11. The fastening element 95 is essentially a fork-shaped component with three teeth and a grip guided in the trigger housing 81. The rear sides of the bearing segments 65 each bear against an outer toothing 93. The central teeth 94 are located between the mutually facing bearing segments 65.

A trigger element 82 in the form of a push button is also guided longitudinally in the trigger housing 81. An expansion rod 89 is integrally formed on the trigger element, for example centrally. According to fig. 8, the expansion rod is supported on a central prong 94 of a fastening element 95. For this purpose, the triggering element 82 is blocked until the fastening element 95 is removed.

To trigger the disposable syringe, the fastening element 95 is first pulled laterally completely away from the trigger housing 81. Next, referring to fig. 9, the button 82 is pressed until it bears against the housing web 35. The expansion lever 89 interacts with the wedge surface 66 in this case like a sliding wedge drive. Referring to fig. 10, the draw hooks 62 are spread apart so as to be able to slide unhindered through the recesses 34 into the housing interior 11 in order to act there as a component of the piston actuating ram 60 on the piston 111.

Fig. 12 to 16 show an embodiment of the principle illustrated in fig. 4 to 7. The supporting component is a housing 10. Which has a substantially tubular configuration and is divided into three functional areas 21, 31, 41. According to fig. 12, the upper area is the trigger area 21. Adjacent to which a jacket region 31 is located. An intermediate base 32 is arranged between the two regions, which slightly projects radially beyond the jacket region 31. The intermediate base 32 has a central recess 34, the diameter of which is slightly larger, for example towards the bottom.

In the trigger area 21 of the housing 10, a dimensionally rigid perforated disk 39, for example of metal, is located on the intermediate base 32. The orifice disk 39 is bonded thereto or injection molded thereto. If necessary, a ceramic shield is used instead of the orifice disk 39. The orifice disc 39 or ceramic shield protects the intermediate base 32 from pressure and/or other deformation. It also prevents bonding of the components 32 and 65 in contact therewith.

A fixing area 41 for accommodating a loadable syringe/piston unit 100 is provided below the jacket portion 31. Referring to fig. 16, the fixing region 41 is, for example, three longitudinal slits. The inner wall of this region is provided with a trapezoidal thread 46, for example. According to fig. 12 and 15, the fastening region 41 is surrounded by a support sleeve 49 which is locked to the housing 10.

A syringe/plunger unit 100 is threaded into the acme threads 46. The syringe/piston unit is composed of a syringe 101 and a piston 111. The barrel 101 is, for example, a thick-walled can, the cylindrical outer wall of which is also provided, at least in partial areas, with trapezoidal threads 104.

Rodless piston 111 is disposed in a cylindrical bore of, for example, syringe barrel 101. The piston 111 has an axial annular groove 112 on its at least approximately conically formed front face for receiving a sealing ring 114 or a permanently elastic sealing material. For example, a cylindrical metal plate 116 is put on the end surface of the rear side of the piston 111.

A short, cylindrical, nozzle-like bore 106 is located in the center of the bore of the syringe 101, the syringe base of which at least approximately matches the contour of the front face of the plunger. The diameter of the holes 106 is about 0.1 to 0.5 mm. The hole 106 is 1 to 5 times as long as its diameter. Which opens into a cylindrical recess 107 in the outer end face 103 of the bottom of the barrel 101.

The spring energy store 50 or drive unit of the disposable syringe is arranged between the piston 111 and the trigger area 21. The spring accumulator 50 is a helical compression spring which is disposed on a piston-operated plunger 60 having four draw hooks 62. The spring energy store 50 is mounted in a tensioned manner in the housing 10 by means of the bearing sections 65 of the draw hooks 62. The housing is supported between the inside of the intermediate base 32 and an upper end face of the piston operating plunger 60.

The piston operating plunger 60 is here divided into three regions. Referring also to the description of fig. 1 to 3, the lower region is the plunger slide 76, the middle region is the plunger disc 73 supporting the spring element 50, and the upper region is a bundle consisting of, for example, four draw hooks 62.

In the jacket region 31 of the housing 10, the hooks 62 have at least approximately a cylindrical envelope 63, i.e. their outer wall has the curvature of a sleeve jacket region. The support section 65 has a truncated cone jacket as a envelope. The envelope is also referred to as a wedge profile 66.

The inner wall of each hook 62 is part of a frustoconical envelope 68. This envelope 68 encloses a hollow space 67 in the form of a truncated cone sheath between the draw hooks 62. The larger the cross-section of the hollow space 67, the further it waits for the plunger disc 73. According to fig. 12, the radial slits 69 between adjacent hooks 62 increase in width to approximately 2 times toward the top.

In contrast to fig. 1, the plunger disk 73 according to fig. 12 has, for example, two grooves 74 which face one another.

The hook 62 is inserted with its support section 65 into the trigger region 21. The bearing section 65 is placed securely on the orifice disk 39.

A trigger unit 80 is disposed in the trigger region 21 as an integral trigger element 82 at its upper location. The trigger member 82 is a pot-shaped body, inside which a trigger tube 82 is integrally formed. At the lower end of the outer contour, the triggering element 82 has a circumferential, slightly protruding edge 83. Which latches behind a surrounding flange 22 on the inner wall of the triggering area 21.

The base of the trigger element 82 has a circular recess 84 into which a fastening element 95 is inserted. The trigger tube 87 has a frustoconical wedge-shaped contour 88 at the lower end in the region of the inner wall. In the illustrated embodiment, the taper angle is between 20 and 45 degrees. In the inoperative and fastened state of the disposable syringe, the wedge-shaped contour 88 lies in the upper region of the wedge-shaped contour 66 of the draw hook 62.

The fastening element 95 is a rotationally symmetrical component like the triggering element 82. Which includes a plate 96 and a locking pin 97. The locking pin 97 has a locking region 99 and a bearing region 98. The two regions 98, 99 are frustoconical. Both having for example the same cone angle. At least the cone angle of the locking region 99 corresponds to the cone angle of the hollow space 67. The annular end face of the support region 98 bears against the upper end face of the pull hook 62.

Fig. 13 shows the disposable syringe with the fastening element 95 removed and the trigger element 82 operated, i.e. pressed down. After the fastening element 95 has been pulled out vertically, the wedge-shaped contour 88 of the trigger tube 87 is slid along the wedge-shaped contour 66 of the pull hook 62 by pressing the trigger element 82 downward. The hooks 62 are thereby elastically and/or plastically bent in the radial direction toward the center line 5. The gaps between the individual hooks 62 are used as far as possible at least in the region of the support section 65. The maximum outer diameter of the bearing section 65 is now smaller than the diameter of the bore disk 39. Referring to fig. 14, each draw hook 62 is movable downwardly by the spring element 50 and moves the plunger 111 by means of the plunger slide 76.

Fig. 15 shows a disposable syringe in a commercially common form which has not yet been operated. The fastening element 95 is inserted and the lower end face of the syringe/piston unit 100 is closed off in a sterile manner by means of a peelable adhesive encapsulation 120.

Fig. 17 to 20 show a variant of the disposable syringe in which the hooks 62 are elastically deformed towards the centre line 5 of the disposable syringe. The housing 10 is essentially a smooth tube with a flat base 32 at the top. A central bore 34 is formed in the base 32 for the passage of the piston actuating plunger 60.

A fastening area 41 for receiving an insertable syringe/plunger unit 100 is located in the lower region of the housing 10. The fastening region 41 comprises, for example, six elastic hooks 42 which each end in an inwardly directed hook tip 43. The hook end 43 has a bevel 44 extending over the entire thickness of the hook towards the lower end face 12 of the housing. The length and spring rate of the elastic hooks 42 are designed to allow the installation of the inserts 50, 100 required for the functioning of the disposable syringe, without plastic deformation of the elastic hooks 42.

Referring to fig. 6, one of the inserts is a syringe/plunger unit 100. Referring also to fig. 12, it includes a syringe 101 and a plunger 111. The syringe 101 is, for example, a thick-walled can whose optionally cylindrical outer wall has, for example, 5 circumferential locking ribs 102. The sum of the locking ribs 102 has, for example, a sawtooth shape in cross section, wherein the spacing between the locking ribs 102 is equidistant. The maximum diameter of the locking rib 102 is slightly smaller than the inner diameter of the housing 10 of the fixing area 41. The diameter of the region between adjacent locking ribs 102 corresponds to the smallest diameter of the housing 10 in the region of the hook end 43.

Within the housing 10, a piston operating plunger 60 is disposed between the base 32 and the syringe/piston unit 100. Fig. 12 shows two areas 73, 76 of the lower end of the piston actuating ram 60. The upper region forms, for example, four hooks 62, which hooks 62 do not extend, for example, to the plunger disk 73. Between plunger disk 73 and hook 62 there is a cylindrical section, which also serves to guide spring element 50 according to fig. 16. For this purpose, it has, for example, four short radially projecting ribs which fix the number of turns of the lower part of the spring element 50.

Each hook 62 has a support section 65. Referring to fig. 18 and 19, in the case of a triggered single use syringe, each pull hook bundle has a cylindrical envelope 63. In the region of the bearing section 65, the envelope 63 can also be cylindrical.

In the upper region of the hooks 62, a portion of an annular groove 71 is provided in each hook 62, the center line of which coincides with the center line 5 of the disposable syringe. According to fig. 18 and 19, an expansion disk 91, for example cylindrical, of a triggering element 82 is seated in the annular groove 71. The bottom of the respective annular groove bears resiliently against the radial outer shape of the expansion disc 91. In the unloaded state, the draw hooks 62 are biased in the direction of the center line 5. For example, when the trigger elements 82 are released, they contact on their upper ends.

The trigger element 82 shown in fig. 17 has a mushroom shape as a rotationally symmetrical component. A narrow web is provided on the expansion disc 91, which is integrally formed with its upper end on the trigger disc 92.

To protect the triggering element 82, a fastening element 95 in the form of a cap is fitted over the base 32 of the housing 10.

Fig. 20 shows a side view of the disposable syringe with the cover 95 cut on half side. The syringe/plunger unit 100 is closed with a removable protective membrane 120. According to fig. 16, the trigger element 82 is in the upper position when the disposable syringe is locked. An expansion disc 91 is positioned above the annular groove 71. The draw hook 62 assumes an expanded position, with the support section 65 resting on the top side 33 of the base 32.

If the trigger element 82 is pressed into the piston operating plunger 60 after removal of the cover 95 and tearing off of the protective film 120, the expansion disc 91 of the trigger element 82 snaps into the annular groove 71. The draw hook 62 springs back so that the largest outer diameter of the envelope 66 of the support section 65 is smaller than the diameter of the hole 34, see fig. 18. The spring element 50 now pushes the piston operating plunger 60 downwards, see fig. 19. The injection process is completed by outputting the medicament through the syringe/plunger unit 100.

All parts of the disposable syringe, except for the spring elements 50, 64, are made of plastic or a material similar to plastic or rubber.

List of reference numerals

1: injection solution, medicament

5: center line of disposable syringe

10: the integrated outer casing is provided with a plurality of integrated outer casings,

11: inside the housing

12: lower end surface of the shell

21: trigger area

22: flange

31: sheathing zone

32: base, middle base

33: outer surface, upper end surface

34: openings, holes, recesses

35: web, shell web

36: edge of the housing

37: bearing surface

39: hole plate

41: fastening region for a syringe/piston unit

42: elastic hook

43: hook end

44: inclined plane

46: trapezoidal thread

49: support sleeve

50: spring element, helical compression spring, spring energy store

60: piston-operated plunger

61: pull rod

62: drag hook

63: lower part of the bread

64: helical compression springs, symbolically

65: support section

66: a wedge-shaped outer profile; a wedge-shaped surface; a wedge-shaped profile; upper part of bread

67: hollow space between the draw hooks

68: hollow space bread

69: slits between the draw hooks

71: annular groove

73: plunger disc

74: groove

76: piston slide block

80: trigger unit

81: trigger case, button

82: trigger element

83: edge of a container

84: recess for a fastening element

85: sleeve barrel

86: rectangular tube

87: trigger tube

88: a wedge-shaped surface; a sloped region; wedge profile

89: expansion rod

91: expansion disc

92: trigger disc

93: 95 outer tine

94: 95 center tine

95: fastening element, cover, fork

96: dish

97: locking pin

98: bearing area

99: locking area

100: syringe/piston unit

101: injection tube

102: outer locking rib

103: end face

104: trapezoidal thread

106: holes, nozzles

107: recess in end face

111: piston

112: annular groove

114: sealing ring, seal

116: metal plate

120: protective film, adhesive package

Claims (6)

1. A needle-free disposable injector having a housing (10), in or on which at least one mechanical spring energy store, at least one syringe/piston unit (100) which can be filled with an active substance at least temporarily, at least one piston actuating plunger (60) and at least one triggering unit (80) are arranged in each case at least in regions, wherein the spring energy store (50) comprises at least one pretensioned spring element, and wherein at least a part of the piston actuating plunger (60) is positioned between the spring energy store (50) and a piston (111) of the syringe/piston unit (100),

wherein the spring-loaded piston-operated plunger (60) has at least one tension rod (61) which can be moved transversely at least in some regions and which supports the tensioned spring energy store (50) on at least one bearing surface (37) of the housing (10) by means of a bearing section (65);

wherein the triggering unit (80) is or has at least one triggering element (82) which, when operated, causes or releases a movement of the bearing section (65) away from the bearing surface (37);

wherein two or more draw hooks (62) are provided on the piston operating plunger (60);

wherein a draw hook (62) is formed by the draw rod (61) together with the support section (65), which draw hook (62) in the locked position supportingly overlaps the housing edge (36);

wherein the two or more draw hooks (62) are fixed separately from each other on a plunger disc (73) of the piston operating plunger (60).

2. Disposable syringe according to claim 1, characterized in that a fastening element (95) is provided on the housing (10) or the trigger unit (80), which fastening element fixes the pull hook (62) in the locking position.

3. Disposable syringe according to claim 1, characterized in that the trigger unit (80) is mechanically connected to the piston-operated plunger (60) via a slide wedge transmission (66, 68).

4. Disposable syringe according to claim 1, characterised in that at least one bundle comprising two or more draw hooks (62) is provided on the piston operating plunger (60).

5. The disposable syringe according to claim 1, characterized in that the length of the single draw hook (62) is greater than half the length of the piston operating plunger (60).

6. Disposable syringe according to claim 1, characterised in that in the piston actuating plunger (60) with at least two hooks (62), the centers of gravity of the bearing sections (65) of the hooks (62) are farther apart from one another in the undeformed state than when the piston actuating plunger (60) is inserted into the disposable syringe and is not activated.