Method for controlling a pneumatic multi-cylinder motor and drive system with a pneumatic multi-cylinder motor

Abstract

Method for controlling a pneumatic multi-cylinder motor (2) comprising the steps of: detecting the rotational position of a rotor (5) rotatably mounted on a stator (4) with a sensor device (11), determining the actuator position of a linear actuator (6; 50) arranged between the stator (4) and the rotor (5) from a sensor signal of the sensor device (11) in a control device (16), controlling a venting valve (17; 18; 19) arranged between a fluid source (36) and the linear actuator (6; 50) with a venting signal dependent on the rotational position and determined by the control device (16), and / or controlling a venting valve (17; 18; 19) arranged between the linear actuator (6; 50) and a fluid outlet (37) with a venting signal dependent on the rotational position and determined by the control device (16) for initiating an acceleration force or a braking force between stator (4) and rotor (5).

Description

[0001] The invention relates to a method for controlling a pneumatic multi-cylinder motor and a drive system with a pneumatic multi-cylinder motor.

[0002] From EP 0 038 371 A1, a hydraulic radial piston motor is known which can be switched between four speeds, avoiding the need to shut off individual pistons. The change in speed is effected solely by changing the effective cross-section of the pistons, which are divided into two chambers and provided with separate hydraulic fluid supplies, and the speed switching is carried out by axially adjusting the central control pin between different operating positions.

[0003] EP 1 062 426 B1 discloses a radial piston engine with a stroke ring, a cylinder block rotatably arranged relative to the stroke ring about an axis of rotation, and a plurality of cylinders arranged radially in the direction of the cylinder block, each containing a movable piston which is supported on the stroke ring via a roller, wherein the roller is rotatably mounted on the piston about an axis of rotation parallel to the axis of rotation of the cylinder block and is axially supported on the inner wall of the cylinder with respect to its axis of rotation via roller guides arranged on its end faces, and wherein the roller guides are in a non-displaceable connection with the respective roller in the direction of the piston stroke.

[0004] From US Patent 2010 / 0281860A1, a hydraulic circuit for a vehicle with at least one selectively operated hydraulic auxiliary motor is known. The hydraulic circuit comprises a first circuit consisting, in series, of a first hydraulic pump, a first hydraulic line, at least one hydraulic motor, and a second hydraulic line. A second hydraulic pump and a third valve control the flow of low-pressure fluid from the second pump to the hydraulic motor housing. The low-pressure fluid flowing through the third valve keeps the motor pistons retracted when the motor is not in use. To operate the motor, the third valve is actuated to shut off the second pump and release the pressure from the motor housing. Subsequently, the first and second lines are pressurized to extend the motor pistons.Then the first and second valves are actuated to separate the first and second lines from each other, and the first pump is used to drive the motor.

[0005] US Patent 3,922,956 A discloses a hydraulic motor in which a rotatable piston and cylinder assembly incorporates several roller tappets that run in contact with an annular cam track. To limit contact stresses at high torques, the roller tappets are at least partially located within the cylinders and have an axial length approximately equal to their diameter. To limit guide wear, two fixed guide rings are in sliding contact with the roller end faces. The guide rings fix and hold the rollers axially and ensure that their axes remain parallel. The rollers are connected to the pistons so that they can rotate freely without contacting the track. The rollers are mounted on elastic, low-friction, semi-cylindrical plastic surfaces that transmit the drive to the drive lugs during the piston's working stroke.

[0006] The object of the invention is to provide a method for controlling a pneumatic multi-cylinder motor and a drive system with a pneumatic multi-cylinder motor, with which a wide range of applications can be covered.

[0007] This problem is solved according to a first aspect of the invention for a method for controlling a pneumatic multi-cylinder motor by the following steps: detecting a rotational position of a rotor rotatably mounted on a stator with a sensor device, determining an actuator position of a linear actuator arranged between the stator and the rotor from a sensor signal of the sensor device in a control device, controlling a venting valve arranged between a fluid source and the linear actuator with a venting signal dependent on the rotational position and determined by the control device, and / or controlling a venting valve arranged between the linear actuator and a fluid outlet with a venting signal dependent on the rotational position and determined by the control device to introduce an acceleration force or a braking force between the stator and rotor.

[0008] The control unit is designed to determine the venting signal and / or the venting signal in a predefinable relationship to the rotor's rotational position relative to the stator. It is not mandatory that a proportional relationship exist between the rotational position and the magnitude of the venting signal and / or the venting signal; rather, such a relationship can be defined by one or more mathematical functions forming a pressure regulator and / or an associated table of values.

[0009] Preferably, the ventilation valve and / or the venting valve are designed as proportional valves or as proportionally controllable switching valves.

[0010] When using proportional valves, the control device is designed to provide a time-varying, in particular continuous, control signal as a venting signal to the venting valve and as a purge signal to the purge valve. For example, the venting valve and the purge valve are each designed to be freely and independently controllable, so that the venting signal is provided to the venting valve and the purge signal to the purge valve.

[0011] Alternatively, the venting valve and the exhaust valve can be combined in a single valve, where a specific position of the venting valve is always coupled to a specific position of the exhaust valve. When using such a combination valve, which can be configured, for example, as a 3 / 3-way or 5 / 3-way valve, the venting signal and the exhaust signal are combined into a single fluid control signal. Preferably, the magnitude of the fluid control signal determines whether venting or exhausting occurs through the combination valve.

[0012] Accordingly, the following procedure can be provided for the use of a combination valve comprising a venting valve connected to a fluid source and a venting valve connected to a fluid outlet: A method for controlling a pneumatic multi-cylinder motor comprising the steps of: detecting the rotational position of a rotor rotatably mounted on a stator with a sensor device, determining the actuator position of a linear actuator arranged between the stator and the rotor from a sensor signal of the sensor device in a control unit, controlling a combination valve, which is arranged in particular between a fluid source and the linear actuator, with a fluid control signal dependent on the rotational position and determined by the control unit, in order to vent the linear actuator, and controlling the combination valve.which is additionally arranged between the linear actuator and a fluid outlet, with the fluid control signal dependent on the rotational position and determined by the control device, in order to effect at least partial venting of the linear actuator.

[0013] In the case of the use of proportionally controllable switching valves, it can be provided that the control device for proportional control of the respective switching valve provides the ventilation signal or the venting signal as a pulse width modulation control signal to the ventilation valve or venting valve.

[0014] By venting or de-venting the respective linear actuator, it can increase or decrease the driving force acting between the stator and the rotor, thereby inducing a force between the stator and the rotor. For example, the linear actuator is envisaged as being fixed in place on the stator or the rotor.

[0015] It is particularly preferred that the linear actuator is aligned in a radial direction with respect to a rotation axis for the rotor relative to the stator, and that a direction of movement for the drive piston and the associated piston rod is also aligned in a radial direction.

[0016] The control unit is accordingly designed to determine the ventilation signal or venting signal, which depends on the rotational position between the rotor and stator, based on a sensor signal from the sensor device, and to provide this signal to the ventilation valve or venting valve, respectively. The sensor device connected to the control unit can, for example, be designed as an incremental rotary sensor that provides an electrical sensor signal depending on the rotational position between the rotor and stator. This signal is evaluated in the control unit and used to determine the ventilation signal and the venting signal.

[0017] The control unit, along with the ventilation and venting valves, enables freely programmable commutation for the pneumatic multi-cylinder motor. The supply of energy in the form of compressed air to the linear actuator can be controlled by a slip between the current rotational position of the rotor relative to the stator and the corresponding ventilation or venting signal. This slip, or phase shift, can be varied depending on parameters such as the rotor speed relative to the stator, a speed change request, a torque request, and / or a torque change request.

[0018] It is particularly preferred to implement pressure control for both the ventilation and venting of the linear actuator, such that the discrete ventilation signal, the discrete venting signal, and the fluid control signal (a combination of ventilation and venting signals) are each provided as output signals by at least one pressure controller. To implement the pressure control, the current fluid pressure in the linear actuator is determined by a pressure sensor, which provides a sensor signal to the control unit.

[0019] For example, the linear actuators of the multi-cylinder motor can be designed as pneumatic cylinders, so that for the execution of the method a determination of a piston position of a drive piston arranged linearly movable between the stator and the rotor in a drive cylinder and equipped with a piston rod for force transmission between rotor and stator is carried out on the basis of the sensor signal of the sensor device.

[0020] In an alternative design of the multi-cylinder engine, the linear actuators can be designed as bellows actuators, whose individual length expansion can also be determined by the control unit depending on the sensor signal of the sensor device.

[0021] Advantageous further developments of the invention are the subject of the dependent claims.

[0022] It is advantageous to determine the rotational speed of the rotor relative to the stator from the sensor signal of the sensor device and to adjust the ventilation and / or venting signal to this determined speed. By taking the rotational speed of the rotor relative to the stator into account, the ventilation and / or venting valve can be controlled advantageously, for example, by considering inertial effects during the control of the ventilation and / or venting valve. These inertial effects can result from the mechanical design of the ventilation and / or venting valve or be related to the inertia of the fluid flows that are supplied to or discharged from the linear actuator by the respective ventilation or venting valve.By taking into account the rotational speed between rotor and stator, a more efficient control of the pneumatic multi-cylinder motor can be ensured, which can also be described as variable commentary.

[0023] In a further development of the invention, the control unit provides that it makes a correction to the ventilation signal and / or the venting signal determined as a function of the rotational position, based on at least one physical quantity from the group consisting of: current rotational speed, rotational speed request, current torque, and torque request. The underlying principle is that the ventilation signal and / or the venting signal must not only be changed with the rotational position between the rotor and stator, but rather that, for advantageous control of the respective linear actuator, it is also necessary to consider the actual motion situation of the pneumatic multi-cylinder motor.This applies particularly when a change to an existing state of motion is to be initiated or planned, as is the case, for example, with an externally imposed torque request to increase or decrease the torque. In the case of a speed request, it is assumed that a previously existing, quasi-stationary state is to be changed such that the pneumatic multi-cylinder motor, starting from a current speed, is to increase or decrease the torque output.

[0024] In an advantageous further development of the method, the venting signal follows a venting pressure profile stored in the control unit, which is formed by assigning an individual venting pressure to each rotational position, and / or the venting signal follows a venting pressure profile stored in the control unit, which is formed by assigning an individual venting pressure to each rotational position. It is assumed that, due to the rotation of the rotor relative to the stator, the linear actuator must ensure a cyclically recurring sequence of movements and a resulting force supply in order to maintain the desired rotation of the rotor relative to the stator.The venting pressure profile depends, among other things, on the design of the linear actuator and the design of the rotor's inner surface, where the linear actuator's forces are intended to cause the rotor to rotate relative to the stator. In a pneumatic multi-cylinder motor, for example, the rotor's inner surface may be designed as a sequence of convex and concave curvature sections, and the venting pressure profile, as well as the exhaust pressure profile, may be optimized so that pressure changes for the linear actuator coincide with changes in the slope at a contact point between the linear actuator and the inner surface.

[0025] In a further embodiment of the invention, it is provided that the linear actuator is supplied with a time-varying working pressure during a working cycle, which comprises an expansion phase and a subsequent contraction phase, wherein the working pressure is first increased to a maximum value by venting the linear actuator to initiate the expansion phase, then reduced to an intermediate value by partially venting the linear actuator in a second step, then increased again to the maximum value by further venting of the linear actuator in a third step, and finally reduced to initiate the contraction phase by, in particular, completely venting the linear actuator in a fourth step.This approach reduces the ripple in the torque delivered by the pneumatic multi-cylinder motor, because the provision of maximum force by the respective linear actuator, which is typically associated with a particularly favorable lever ratio between the rotor and stator of the multi-cylinder motor, is avoided due to the temporary partial venting of the respective linear actuator.Rather, in the phase where the force provided by the linear actuator between the stator and rotor would result in maximum torque due to the particularly favorable lever ratio, a reduction in the force provided by the linear actuator is accepted in order to achieve at least a substantial compensation for the deteriorating lever arm in the subsequent movement phase through renewed ventilation of the linear actuator. This, in turn, largely levels out the torque of the pneumatic multi-cylinder motor, which results from the interaction of several linear actuators. For example, it is intended that the linear actuator is subjected to maximum pressure within an initial period of time that corresponds to approximately 25 percent of the cycle duration of the operating cycle (i.e., the sequence of expansion and contraction phases for the linear actuator).In a second period, following the first and also lasting approximately 25 percent of the operating cycle, the linear actuator is vented to the intermediate pressure. In a subsequent third period, also approximately 25 percent of the operating cycle, the linear actuator is vented again to the maximum pressure. Finally, in a fourth period, also approximately 25 percent of the operating cycle, the linear actuator is vented completely. It should be understood that in this context, "venting" and "venting" of the linear actuator refer to the fluidic supply of a working chamber formed within the linear actuator.

[0026] In an advantageous further development of the method, the ventilation valve and the venting valve are used for the synchronous fluid supply of several linear actuators arranged on the stator in the direction of rotation of the rotor. These actuators form a fluidically coupled actuator group, and the control device performs a phase-shifted control of the actuator groups. This phase shift depends on the distribution of the linear actuators and on the profiling of an inner surface of the rotor on which the linear actuators are supported. Furthermore, the linear actuators belonging to each actuator group are vented and vented synchronously in the same manner, except for any delays caused by different line lengths.This enables the linear actuators of each actuator group to synchronously apply a force to different sections of the rotor's inner surface, as required for the desired rotational movement of the rotor relative to the stator. Preferably, the linear actuators belonging to an actuator group are arranged at a fixed angular interval relative to each other. For example, a fluidic multi-cylinder engine can be equipped with three groups of three linear actuators each, with the linear actuators of each actuator group being offset from each other by 120 degrees and the respective actuator groups being offset from each other by 40 degrees.Thus, the linear actuators of the three actuator groups form a radial motor in which, due to a preferably radially outward-directed, group-wise linear movement of the linear actuators, the desired provision of driving forces and a resulting torque of the rotor relative to the stator can be generated.

[0027] In a further embodiment of the invention, the control device performs a phase-shifted control of several valve groups, each comprising a ventilation valve and a venting valve, and each of which is assigned to one of several actuator groups. Preferably, the phase shift with which the control device controls the different valve groups corresponds to the angular offset that two adjacent actuator groups have.

[0028] In an advantageous further development of the method, the control unit utilizes a sensor signal from the sensor device for torque control and / or position control of the rotor's rotational movement relative to the stator. By way of example, it is provided that the rotational position of the rotor relative to the stator and an associated ventilation or venting signal allow for the inference of force being applied from the stator to the rotor via the linear actuator. By taking into account the geometry of the rotor's inner surface, a resulting force in the direction of rotation, transmitted from the linear actuator to the rotor, can then be calculated. Knowing this force and the geometry of the rotor's inner surface, appropriate ventilation or venting can be controlled to ensure at least a substantially, preferably completely, constant torque provided by the rotor.Venting of the linear actuator or the plurality of linear actuators, in particular a plurality of actuator groups, must be carried out.

[0029] In an alternative operating mode, the control unit can use the sensor signal from the sensor device to control the position of the rotor's rotation relative to the stator. In this case, it can also be provided, for example, that the rotor can be fixed in a predetermined rotational position by appropriately venting or de-venting the linear actuators, as can be done, for instance, when using a pneumatic multi-cylinder motor as an actuator in a machine tool or at the joint of a robot.

[0030] According to a second aspect, the object of the invention is achieved by a drive system with a pneumatic multi-cylinder motor. The pneumatic multi-cylinder motor comprises a stator and a ring-shaped rotor with a profiled inner surface, which is rotatably mounted on the stator about an axis of rotation. Several pneumatic linear actuators are arranged between an outer surface of the stator and the inner surface of the rotor, each of which is designed to introduce a radial force component between the stator and the rotor.Furthermore, the drive system includes a pneumatic supply unit comprising a control unit and several ventilation and venting valves connected to the control unit, as well as a sensor unit attached to the pneumatic multi-cylinder motor and connected to the control unit, which is designed to detect a rotational position of the rotor relative to the stator and to provide a sensor signal to the control unit that depends on the rotational position.The control device serves to control the ventilation valve, which is arranged between a fluid source and the respective linear actuator, with a ventilation signal dependent on the rotational position and determined by the control device, and / or to control the venting valve, which is arranged between the respective linear actuator and a fluid outlet, with a ventilation signal dependent on the rotational position and determined by the control device, to initiate an acceleration force or with a venting signal to initiate a braking force between rotor and stator.

[0031] For example, such a drive system can be used as a drive for a stirring device or as a drive for a robot.

[0032] It is particularly preferred that the control device is designed for carrying out the method according to the invention and / or that the ventilation valves and the venting valves are each designed as electrically or pneumatically controlled proportional valves.

[0033] An advantageous embodiment of the invention is shown in the drawing. Here, the drawing shows: Fig. 1 a strictly schematic representation of a drive system with a pneumatic multi-cylinder motor having a plurality of linear actuators and to which a control device is assigned, comprising several proportional valves each designed as combined ventilation and venting valves, Fig. 2 a schematic representation of a second embodiment of a linear actuator, Fig. 3 a diagram with a schematic representation of pressure profiles for three linear actuators arranged 120 degrees out of phase and a resulting torque of the pneumatic multi-cylinder motor without implementing pressure control for the respective pressure profile, and Fig. 4 a diagram with a schematic representation of pressure profiles for three linear actuators arranged 120 degrees apart in phase and a resulting torque of the pneumatic multi-cylinder motor with implementation of a pressure control for the respective pressure profile.

[0034] One in the Fig. 1 The schematically represented drive system 1 comprises a pneumatic multi-cylinder motor 2 and a pneumatic supply device 3 and serves to provide a rotational movement about a rotational axis 10.

[0035] The multi-cylinder motor 2 comprises a stator 4 arranged centrally around the axis of rotation 10, a rotor 5 rotatably mounted on the stator 4 around the axis of rotation 10 (not shown in detail), and a plurality of linear actuators 6. For illustrative purposes, the linear actuators 6 are each fixedly mounted to the stator 4 by means of an actuator housing 20. As described in more detail below, several of the linear actuators 6 are pneumatically grouped together to form a first actuator group 7. Further linear actuators 6 form a second actuator group 8 and a third actuator group 9, respectively. It is provided that the linear actuators 6 of each actuator group 7 to 9 are controlled fluidically in a synchronized manner, i.e., they are synchronously pressurized and vented.

[0036] In the region of the axis of rotation 10, a sensor device 11 is arranged, comprising a sensor wheel 28 non-rotatably connected to the rotor 5 and a sensor 29 non-rotatably connected to the stator 4. For example, the sensor wheel 28 is provided on its outer circumference with a plurality of permanent magnets, which can be scanned by the sensor 29, which can be, for example, a Hall sensor, in order to detect the rotational position of the motor 5 relative to the stator 4 without contact. For this purpose, the sensor 29 is electrically connected via a sensor line 12 to a control unit 16, in which the sensor signals from the sensor 29 can be evaluated.

[0037] The first actuator group 7 is connected to a first proportional valve 17 via a first pneumatic line 13. The second actuator group 8 is connected to a second proportional valve 18 via a second pneumatic line 14. The third actuator group 9 is connected to a third proportional valve 19 via a third pneumatic line 15. Each of the proportional valves 17, 18, and 19 is electrically connected to the control unit 16 via an associated control line 30, 31, 32, which is designed to provide electrical control signals to the respective proportional valve 17, 18, 19.

[0038] By way of example, proportional valves 17, 18, and 19 are each designed as 5 / 3-way valves and thus serve as both a venting and a purge valve for the respective actuator group 7, 8, and 9, with a fixed coupling between the venting and purge functions. Alternatively, the pneumatic circuit can also be implemented using 3 / 3-way valves.

[0039] As an example, the proportional valves 17, 18 and 19 are connected via supply lines 33, 34, 35 to a compressed air source 36, which is designed to supply compressed air to the respective actuator groups 7, 8 and 9. Furthermore, the proportional valves 17, 18 and 19 are each coupled to an outlet line 37 and an associated silencer 38, thereby enabling a sound-dampened discharge of compressed air from the respective actuator group 7, 8, 9.

[0040] In an embodiment of a supply device not shown, the actuator groups 7, 8 and 9 are each assigned discretely designed ventilation valves and discretely designed venting valves, which are each designed as proportional valves or as pulse-controlled switching valves and can each be individually controlled by the control device 16 in order to ensure the ventilation and venting of the respective actuator group 7, 8, 9.

[0041] As the depiction of the Fig. As can be seen from Figure 1, the multi-cylinder motor 2 comprises a total of nine linear actuators 6, which extend radially outwards at equal angular intervals relative to the axis of rotation 10. Each linear actuator 6 includes an actuator housing 20, which is fixed to the stator 4 at one end and is shown to be sleeve-shaped. A circular-cylindrical drive piston 22 is linearly movable along an axis of movement 40 in the recess in the actuator housing 20, also referred to as the drive cylinder 21, and thus defines a variable-sized working chamber 42 within the drive cylinder 21. The working chamber 42 is fluidically connected to the respective proportional valve 17, 18, 19 in a manner not shown in detail.

[0042] The drive piston 22 is connected to a piston rod 23, which projects radially outwards along the axis of movement 40 beyond the actuator housing 20. A coupling roller 24 is rotatably mounted at an end region of the piston rod 23 facing away from the actuator housing 20 and is designed to bear against an inner surface 25 of the rotor 5. The piston rod 23 is partially surrounded by a return spring 42, which is supported against opposing surfaces of the drive piston 22 and the actuator housing 20. The return spring 42 is installed with an internal preload between the drive piston 22 and the actuator housing 20 and thus ensures that the drive piston 22 and the associated piston rod 23 return to a radially inward rest position, provided that no pressurization is provided in the working chamber 41 which leads to pressure forces with which the spring force of the return spring 42 can be overcome.

[0043] Each of the actuator groups 7, 8, 9 comprises, by way of example, three linear actuators 6, which are connected via an associated ring line 43, 44, and 45, respectively, to the associated pneumatic line 13, 14, and 15. The linear actuators 6 of each actuator group 7, 8, 9 are arranged offset from each other by 120 degrees. Linear actuators 6 of adjacent actuator groups 7, 8, 9 are connected in the Fig. In the embodiment shown in 1, the two are arranged offset from each other by 40 degrees.

[0044] The inner surface 25 of the rotor 5 is designed as a sequence of concave regions 26 and convex regions 27, the terms "concave" and "convex" being used in relation to the axis of rotation 10. The concave regions 26 and the convex regions 27 transition smoothly into one another, with six concave regions 26 and six convex regions 27 being provided as examples, arranged at uniform angular intervals with respect to the axis of rotation 10.

[0045] Alternatively to those in the Fig. The multi-cylinder engine 2 can also be equipped with linear actuators 50 of the type shown in Figure 1, as described in the Fig. Figure 2 shows the linear actuator 50, a bellows actuator in which the linear relative movement along a motion axis 58 is effected by a change in the shape of a bellows 53. The bellows 53 is rotationally symmetrical to the motion axis 58, has a double-S-shaped profile, and is made of a rubber-elastic material. The bellows 53 can also be described as a circular cylindrical sleeve with a central constriction.

[0046] The bellows 53 is provided at each end with a base plate 51 and a cover plate 52, respectively, both made of a dimensionally stable material, in particular plastic or metal. The bellows 53, the base plate 51, and the cover plate 52 are designed such that a sealing connection is established between the bellows 53 and the base plate 51, and between the bellows 53 and the cover plate 52. Accordingly, an inner surface 59 of the bellows 53, an inner surface 60 of the base plate 51, and an inner surface 61 of the cover plate 52 define a working space 62, which can be supplied with compressed air via a working connection 56 formed in the base plate 51 in order to cause elastic expansion of the linear actuator 50 by deformation of the bellows 53, as described in the Fig. 2 is symbolized by the expansion arrow 64. When the pressure level in the working space 62 decreases, the internal stresses of the elastically deformed bellows 53 cause the linear actuator 50 to return to the neutral position, as described in the Fig. Figure 2 shows that to prevent the base plate 51 from tilting relative to the top plate 52, a stabilizing rod 55 is fixed to the top plate 52. This rod is preferably arranged coaxially with the axis of movement 58 and passes through a recess 63 in the base plate 51. To prevent the escape of compressed air between the stabilizing rod 55 and the recess 63, sealing materials (not shown in detail) are provided there.

[0047] For fixing the linear actuator 50 to the stator 4, fastening means designed as threaded bores 65 are provided in the base plate 51. A support roller 54 is rotatably mounted on an axle 66 on the top plate 52. The axle is fixed to cantilevers 67, which are, for example, integrally formed with the top plate 52.

[0048] The diagram according to the Fig. Figure 3 shows, strictly schematically and not to scale, pressure profiles p1, p2 and p3 for three linear actuators 6 arranged each 120 degrees out of phase, each of which corresponds to one of the actuator groups 7, 8, 9 according to the Fig. The pressure profiles p1, p2, and p3 assume that the respective proportional valves 17, 18, and 19 are used as switching valves without pressure regulation. The maximum supply pressure is established almost instantaneously after the respective proportional valve 17, 18, and 19 are actuated into the venting position, resulting in a maximum pressure px in the working chamber 41 of the respective linear actuator 6. This allows the respective linear actuator 6 to provide its maximum force almost instantaneously. Due to the geometry of the inner surface 25 of the rotor 5, against which the respective linear actuator applies its force, a torque profile M1 is established for the torque generated by the respective linear actuator. This torque can be assumed to be a half-wave of a sine curve and is shown. At the end of each operating cycle, the working chamber 43 is vented back to the ambient pressure pa.The successive activation of the actuator groups 7, 8, 9 results in a total torque 85, shown separately for the sake of improved illustration, which exhibits considerable ripple.

[0049] The diagram according to the Fig. Figure 4 shows, strictly schematically and not to scale, pressure profiles p4, p5 and p6 for three linear actuators 6 arranged each 120 degrees out of phase, each of which corresponds to one of the actuator groups 7, 8, 9 according to the Fig.The pressure profiles p4, p5, and p6 assume that the respective proportional valves 17, 18, and 19 are controlled by output signals from a pressure regulator. A purely exemplary operating cycle extends between time t0 and time t4. In a first step, extending from t0 to t1, a slightly slower pressure build-up is provided for the working chamber 41 of the respective linear actuator 6 compared to unregulated valve control. At the end of this first step, the maximum pressure px, which can correspond in particular to the supply pressure for the pneumatic multi-cylinder motor 2, is reached. In a second step, extending from t1 to t2, the working chamber 41 of the respective linear actuator 6 is vented from the maximum pressure px to an intermediate pressure pz.In a third step, extending from t2 to t3, the working chamber 41 of the respective linear actuator 6 is vented again from the intermediate pressure pz to the maximum pressure px. In a fourth step, extending from t3 to t4, the working chamber 41 of the respective linear actuator 6 is vented from the maximum pressure px to an ambient pressure pa.

[0050] In each of steps 1 to 4, pressure control is provided for the pressure in the working chamber 43, resulting in a torque curve M2 for the respective linear actuator 6 of the pneumatic multi-cylinder motor 2, which can be assumed to be an almost rounded rectangle and is shown. The sequential control of the actuator groups 7, 8, 9 results in a total torque 86, shown separately for clarity, which exhibits a slight ripple.

Claims

[1] Method for controlling a pneumatic multi-cylinder engine (2) with the steps: detecting a rotational position of a rotor (5) rotatably mounted on a stator (4) with a sensor device (11), determining an actuator position of a linear actuator (6; 50) arranged between the stator (4) and the rotor (5) from a sensor signal of the sensor device (11) in a control device (16), controlling a ventilation valve (17; 18; 19) arranged between a fluid source (36) and the linear actuator (6; 50) with a ventilation signal that is dependent on the rotational position and determined by the control device (16), and / or controlling a vent valve (17; 18; 19) arranged between the linear actuator (6; 50) and a fluid outlet (37) with a ventilation signal that is dependent on the rotational position and determined by the control device (16). Bleeding signal for introducing an acceleration force or a braking force between the stator (4) and the rotor (5). [2] Method according to claim 1, characterized by that a speed for a rotation of the rotor (5) relative to the stator (4) is determined from the sensor signal of the sensor device (11) and that the ventilation signal and / or the ventilation signal are adapted to the determined speed. [3] Method according to claim 2, characterized by that the control device (16) carries out a correction for the ventilation signal determined as a function of the rotational position and / or for the ventilation signal determined as a function of the rotational position as a function of at least one physical variable from the group: current speed, speed requirement, current torque, torque requirement. [4] Method according to claim 3, characterized bythat the ventilation signal follows a ventilation pressure profile stored in the control device (16), which is formed by assigning an individual ventilation pressure to each rotational position and / or that the ventilation signal follows a ventilation pressure profile stored in the control device (16), which is formed by assigning an individual ventilation pressure to each rotational position. [5] Method according to one of claims 1 to 3, characterized byin that the linear actuator (6; 50) is supplied with a time-variable working pressure during a working cycle which comprises an expansion phase and a subsequent contraction phase, wherein the working pressure is raised to a maximum value in a first step by venting the linear actuator (6; 50) to initiate the expansion phase, is reduced to an intermediate value in a second step by partially venting the linear actuator (6; 50), is raised again to the maximum value in a third step by further venting the linear actuator (6; 50) and is reduced in a fourth step by venting, in particular completely, the linear actuator (6; 50) to initiate the contraction phase. [6] Method according to one of the preceding claims, characterized bythat the ventilation valve (17, 18, 19) and the vent valve (17, 18, 19) are used for a synchronous fluid supply to a plurality of linear actuators (6; 50) arranged on the stator (4) in a manner distributed in the direction of rotation of the rotor (5), which linear actuators form a fluidically coupled actuator group (7, 8, 9), and that the control device (16) carries out a phase-shifted control of the actuator groups (7, 8, 9), which depends on a distribution of the linear actuators (6; 50) and on a profiling of an inner surface (25) of the rotor (5) on which the linear actuators (6; 50) are supported. [7] Method according to claim 6, characterized by that the control device (16) carries out a phase-shifted control of a plurality of valve groups (17, 18, 19), each of which comprises a ventilation valve and a venting valve and is each assigned to one of a plurality of actuator groups (7, 8, 9). [8] Method according to one of the preceding claims, characterized by that the control device (16) uses a sensor signal of the sensor device (11) for torque control and / or for position control for the rotational movement of the rotor (5) relative to the stator (4). [9] Drive system (1) with a pneumatic multi-cylinder motor (2) which comprises a stator (4) and a rotor (5) which is mounted on the stator (4) so as to be rotatable about a rotation axis (10) and is ring-shaped and has a profiled inner surface (25), wherein a plurality of pneumatic linear actuators (6;25) are arranged, each of which is designed to introduce a radial force component between the stator (4) and the rotor (5), and with a pneumatic supply device (3) which comprises a control device (16) and a plurality of ventilation valves (17, 18, 19) and vent valves (17, 18, 19) connected to the control device (16), and with a sensor device (11) which is attached to the pneumatic multi-cylinder engine (2) and connected to the control device (16), and which is designed to detect a rotational position of the rotor (5) relative to the stator (4) and to provide a sensor signal which is dependent on the rotational position to the control device (16), wherein the control device (16) is designed to control a ventilation valve (17, 18, 19) which is connected between a fluid source (36) and the respective linear actuator (6;50) is arranged, with a ventilation signal which is dependent on the rotational position and determined by the control device (16), and / or for controlling a venting valve (17, 18, 19) which is arranged between the respective linear actuator (6; 50) and a fluid outlet (37), with a venting signal which is dependent on the rotational position and determined by the control device (16) for introducing an acceleration force or a braking force between the stator (4) and the rotor (5).; [10] Drive system (1) according to claim 9, characterized by that the control device (16) is designed to carry out the method according to one of claims 1 to 8 and / or that the ventilation valves (17, 18, 19) and the venting valves (17, 18, 19) are each designed as electrically or pneumatically controlled proportional valves.

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