Flap device for controlling a fluid flow of an internal combustion engine, - with a flap housing which surrounds in a circumferential direction at least one channel section through which the fluid flow can flow in an axial direction, - with at least one flap which, for controlling a cross-section which can be flowed through of the channel section, is disposed pivotably in the flap housing around a pivoting axis extending perpendicularly to the axial direction, - with an actuating device for driving the flap, which has a linearly adjustable drive shaft, - with a coupling device which couples a flap shaft, which is non-rotatably connected with the flap and extends coaxially to the pivoting axis, with the drive shaft positioned coaxially to the pivoting axis, such that it transforms linear movements of the drive shaft into rotatory movements of the flap shaft, - wherein the actuating device is formed as a hydraulically or pneumatically controllable pressurised container, - wherein the pressurised container has in a pressurised container housing a control room which is restricted by an elastic membrane, which is rigidly connected with the drive shaft, wherein the pressurised container housing has a control connection which is fluidically connected with the control room, through which control connection an overpressure or an under pressure can be applied to the control room in order to adjust the membrane, - wherein the pressurised container housing has a basic body and a lid which closes an assembly opening, facing towards the flap, of the basic body, - wherein the lid is integrally formed with the flap housing, - wherein the coupling device disposed externally to the pressurised container housing, - wherein the drive shaft is drawn out of the pressurised container housing through a wall section of the pressurised container housing, wherein between the drive shaft and the wall section is formed a linear drive which supports the torque, characterised in that the coupling device disposed axially between a housing of the actuating device and the flap housing. - with a flap housing which surrounds in a circumferential direction at least one channel section through which the fluid flow can flow in an axial direction, - with at least one flap which, for controlling a cross-section which can be flowed through of the channel section, is disposed pivotably in the flap housing around a pivoting axis extending perpendicularly to the axial direction, - with an actuating device for driving the flap, which has a linearly adjustable drive shaft, - with a coupling device which couples a flap shaft, which is non-rotatably connected with the flap and extends coaxially to the pivoting axis, with the drive shaft positioned coaxially to the pivoting axis, such that it transforms linear movements of the drive shaft into rotatory movements of the flap shaft, - wherein the actuating device is formed as a hydraulically or pneumatically controllable pressurised container, - wherein the pressurised container has in a pressurised container housing a control room which is restricted by an elastic membrane, which is rigidly connected with the drive shaft, wherein the pressurised container housing has a control connection which is fluidically connected with the control room, through which control connection an overpressure or an under pressure can be applied to the control room in order to adjust the membrane, - wherein the pressurised container housing has a basic body and a lid which closes an assembly opening, facing towards the flap, of the basic body, - wherein the lid is integrally formed with the flap housing, - wherein the coupling device disposed externally to the pressurised container housing, - wherein the drive shaft is drawn out of the pressurised container housing through a wall section of the pressurised container housing, wherein between the drive shaft and the wall section is formed a linear drive which supports the torque,