Actuator

[0002] The invention concerns an actuator.

[0003] In EP 344 183 B1 has been described an actuator in the form of a locking shaft coupling in which a quick engagement and disengagement of two shaft parts is made possible by the fact that at least one of the two coupling halves is equipped with drivers which mesh in recesses of the other clutch half or of a part connected therewith and the relative position of the drivers is changeable to two shift positions so that different angles of rotation can be set between the shaft parts to be coupled. The coupling halves have distributed on the periphery drivers in the form of drag bolts carrying rollers. The latter mesh in recesses designed as guide grooves of a coupling sleeve.

[0004] In the prior art such as described in EP 344 183 B1, the fact that because of the constructional principle with the drivers distributed on the periphery a large radial installation space is required has a disadvantageous effect which above all limits the ground clearance in off road vehicles and the multiplicity of small parts creates a high susceptibility to dirt capable of impairing the operation.

[0005] This invention is based on the problem of designing an actuator, which by virtue of its small radial extension, does not limit the ground clearance of vehicles.

[0006] As result of the compact design mainly in radial direction and the reduced number of parts susceptible to interference and dirt, the actuator according to the invention is particularly suited to installation in vehicles used in difficult terrains. By integrating drag and prestressed springs in a housing, installation space and multiplicity of parts are reduced.

[0007] Different embodiments of this invention are fundamentally described herebelow with the aid of drawings where:

[0008] FIG. 1 is a constructional embodiment of an actuator according to the invention; and

[0009] FIGS. 2 and 3 are examples of utilization of an actuator according to the invention.

[0010] In FIG. 1 is shown the constructional assembly of an actuator according to the invention. A housing 1 is firmly connected with a stabilizer 2. A cover is firmly connected with a stabilizer 2 and the housing 1 acts as first coupling part 4 which has a coupling spline 10. A second coupling part 5 is movably mounted in the housing 1 and provided with a seal 6 which encloses in one pressure chamber 8 for actuation pressure introduced by a connection 7. The coupling part 5 is biased by a spring 9 against the pressure acting in the pressure chamber 8, i.e. a disengagement operation occurs when the pressure force is increased. In case of a low pressure but elevated spring tension, an engagement takes place.

[0011] In FIG. 1 is shown a disengaged situation. The coupling splines 10 and 11 are here separated from each other to the extent that the coupling part 5, which is axially movable via a shaft spline 12, and radially fixed with a stabilizer 13, allows a rotation between the stabilizer 2 and the stabilizer 13 without torsional stress occurring at the same time. The stabilizer 13 is supported in the area of the shaft spline 12 and in a guide part 14, sealed, and axially fixed with fastening means 15, 16 and 17, such as snap rings or locking rings. The guide part 14 serves at the same time as sealing carrier for sealing relative to the housing 1 and, via a fastening means 16, for reinforcing the spring tension, relative to the housing 1. A connection 18 placed in the housing 1 serves to restore potential leakage of the sealing 6 and to fill a low-pressure chamber 19. In an operational variation, said low-pressure chamber 19 is also energized with back pressure for reinforcing the spring tension. The connections 7 and 18 communicate, via respective holes 20 and 21, in the housing 1 with the pressure chamber 8 and the low-pressure chamber 19. By reducing the diameter of the holes 20 and 21, a hydraulic damping can also be produced by the actuator 22 according to the invention. The coupling parts 4 and 5 axially overlap always in the disengaged state so that the stabilizers 2 and 13 are automatically engaged in case of a drop of pressure.

[0012] FIG. 2 shows a utilization of the actuators 22 and 23 according to the invention with an accessory energy-supply and control system.

[0013] The actuators 22 and 23, according to the invention, are supported in rocking bearings 24, 25, 26 and 27 on the vehicle bottom, not shown, of a multiple-axle vehicle. On the outer ends of the equally constructed stabilizers 2 and 13, additional rocking bearings 28, 29, 30 and 31 are placed which fix the stabilizers 2 and 13 also axially on respective vehicle axles 38 and 39.

[0014] The pressure required for the disengagement process of the actuators 22 and 23 is produced by an electromagnetically actuatable control valve 34 installed in a return pipe 32 of a hydraulic steering system 33. The control valve 34 is actuated in the low speed range for the cases when the vehicle would effect great wobbling movements in difficult terrain via rigid stabilizers. The disengagement can speed-dependently result automatically by an electronic control 36, via a speed signal, delivered by a tachometer 35 or can be manually activated via a switch, not shown. For reasons of safety, however, the engagement must automatically result when a high transverse acceleration appears and depending on a speed limit.

[0015] The control valve 34 is advantageously shifted so that the power coupling on the actuators 22 and 23, i.e. the engagement of both coupling parts 4 and 5, takes place automatically in case of breakdown of the electric system. This is required in order to limit the wobbling angle at elevated speeds and transverse accelerations. Since the driving in difficult terrain at low speeds with disengaged actuators 22 and 23 constitutes a very small time portion in the utilization of the vehicle, it is especially advantageous for energy supply to use the oil hydraulic system of the steering system 33.

[0016] Shown in FIG. 3, the example of utilization stands out by an alternative control of the actuators 22 and 23 according to the invention. At very strong actuator forces, the hydraulics of the steering system is used to reinforce the spring 9 during the engagement process.

[0017] 1 housing

[0018] 2 stabilizer

[0019] 3 cover

[0020] 4 coupling part

[0021] 5 coupling part

[0022] 6 sealing

[0023] 7 connection

[0024] 8 pressure chamber

[0025] 9 spring

[0026] 10 coupling profile

[0027] 11 coupling profile

[0028] 12 spline shaft

[0029] 13 stabilizer

[0030] 14 guide part

[0031] 15 fastening means

[0032] 16 fastening means

[0033] 17 fastening means

[0034] 18 connection

[0035] 19 low-pressure chamber

[0036] 20 hole

[0037] 21 hole

[0038] 22 actuator

[0039] 23 actuator

[0040] 24 rocking bearing

[0041] 25 rocking bearing

[0042] 26 rocking bearing

[0043] 27 rocking bearing

[0044] 28 rocking bearing

[0045] 29 rocking bearing

[0046] 30 rocking bearing

[0047] 31 rocking bearing

[0048] 32 return pipe

[0049] 33 steering system

[0050] 34 control valve

[0051] 35 tachometer

[0052] 36 electronic control

[0053] 37 control valve