LINEAR ACTUATOR

Abstract

Linear actuator comprising a housing (1) with an electric motor (6), which through a transmission (12) drives a spindle (10) with a spindle nut (13). To the spindle nut (13) is secured a tubular adjustment element (3), which is guided in a guide tube (2). A bushing (15) is secured at the rear end of the guide tube (2) by means of which the guide tube (2) is secured to the chassis (7) of the actuator. Expediently, the securing is done with stampings (16) from the outer side of the mounting bushing (15) and into the guide tube (2). These stampings (16) are appropriately done opposite channels, such as screw channels (17) in the guide tube (2), such that the stampings (16) are received in the channels and moreover do not in a disrupting manner protrude into the guide tube (2) and prevent the movement of the spindle nut (13) and the adjustment element (3), respectively.

Claims

1. A linear actuator comprising a housing, an electric motor a transmission, a spindle in connection with the transmission, a spindle nut on the spindle, a tubular adjustment element, which with a rear end is connected to the spindle nut, a guide tube for the tubular adjustment element, a chassis in which the guide tube with a rear end is secured, wherein it comprises a mounting bushing in which the rear end of the guide tube is secured and where the mounting bushing is secured to the chassis.

2. The linear actuator of claim 1 wherein stampings are done from the outer side of the mounting bushing and into the guide tube for retaining the guide tube.

3. The linear actuator of claim 2 wherein the stampings are made opposite of channels, such as screw channels in the guide tube, such that the stampings are received in the channels.

4. The linear actuator of claim 1 wherein the outer diameter of the guide tube and the inner diameter in the mounting bushing are adapted to each other, such that the guide tube with a forced fit protrudes into the mounting bushing.

5. The linear actuator of claim 1 wherein a rear end of the mounting bushing is designed with a radially protruding flange comprising screw holes with internal threads.

6. The linear actuator of claim 1 wherein the mounting bushing with guide tube is secured with the rear mounting around the chassis, in that screws are led from the rear mounting through the chassis to the screw holes in the mounting bushing, by which the rear mounting and the mounting bushing are tightened around the chassis.

7. The linear actuator of claim 1 wherein the mounting bushing is of steel and the guide tube is of light metal, such as aluminum.

8. The linear actuator of claim 1 wherein the chassis comprises at least one lock hole and where the front end of the electric motor comprises at least one flap prepared for engagement with the lock hole, by which the electric motor can be fixed to the chassis.

9. The linear actuator of claim 8 wherein the chassis comprises at least one depression and where the front end of the electric motor comprises at least one protrusion prepared for engagement with the depression.

10. The linear actuator of claim 1 wherein the chassis comprises at least one through-going hole and where the front end of the electric motor (6) comprises at least one hole prepared for engagement with fastening means (31,32), and where the fastening means are led through the through-going hole, by which the electric motor is secured to the chassis.

Description

[0010] A linear actuator according to the invention will be described more fully below with reference to the accompanying drawing. The drawing shows:

[0011] FIG. 1, a linear actuator,

[0012] FIG. 2, the same as FIG. 1, but without housing,

[0013] FIG. 3, the same as FIG. 2, but further without guide tube and chassis,

[0014] FIG. 4, the same as FIG. 3, seen from the other side and where the front mounting and bushing in the guide tube are shown,

[0015] FIG. 5, a perspective view of a rear most part of the guide tube with mounting bushing,

[0016] FIG. 6, guide tube with mounting bushing seen directly from the front,

[0017] FIG. 7, a longitudinal section through the guide tube and mounting bushing in FIG. 5,

[0018] FIG. 8, an exploded view of the linear actuator,

[0019] FIG. 9, an exploded view of the electric motor and the chassis shown in perspective,

[0020] FIG. 10, an exploded view of the electric motor and the chassis shown in a different perspective, and

[0021] FIG. 11, an exploded view shown in perspective where the electric motor and the chassis are assembled,

[0022] FIG. 12, an exploded view of a second embodiment of the electric motor and the chassis shown in perspective, and

[0023] FIG. 13, an exploded view of the second embodiment of the electric motor and the chassis shown in a different perspective.

[0024] The linear actuator outlined in the drawing comprises a housing 1 consisting of a first portion 1a and a second portion 1b. Further, the linear actuator comprises a guide tube 2 and a tubular adjustment element 3 guided in this. For mounting the actuator, a rear end of the housing 1 is equipped with a rear mounting 4 and in a front end of the tubular adjustment element 3 there is a front mounting 5. Both the rear mounting 4 as well as the front mounting 5 has an eye, a through-going hole 4a,5a for a bolt, rivet, axle pin or the like, by means of which the linear actuator can be secured. The linear actuator is thus able to rotate about a central axis through the eye both in the rear mounting 4 as well as in the front mounting 5, such that the linear actuator automatically adapts to the position of the two elements in the structure to which the linear actuator is secured, such that the forces ideally always run axially in the longitudinal direction of the tubular adjustment element 3. As it appears from FIG. 2, the linear actuator comprises an electric motor 6, typically a reversible electric motor, which can be either a DC or AC motor for low voltage or mains voltage. To a front end of the electric motor 6 a chassis 7 in the shape of a housing is mounted, which together with the electric motor 6 constitutes the main components of the linear actuator.

[0025] The rear mounting 4 is mounted on a rear end of the chassis 7 while the guide tube 2 with a rear end is mounted to a front end of the chassis 7. In connection with the electric motor 6 there is a printed circuit board 8 with a plug 9 for connecting the linear actuator to a power supply and possibly also to an electric controller.

[0026] The linear actuator further comprises a spindle 10, where a bearing 11 is mounted on a rearmost part thereof, by which the spindle is embedded and mounted in the chassis 7. The spindle 10 is driven by the electric motor 6 through a transmission 12, here a worm gear, where an extension of the shaft of the electric motor 6 is designed as a worm 12a in engagement with a worm wheel 12b, mounted on the spindle 10.

[0027] The spindle 10 has external threads, where a spindle nut 13, which is secured against rotation having internal threads, is in engagement with the threads of the spindle 10. A rear most part of the spindle nut 13 is equipped with fins 13a, which extends into axially running tracks internally in the guide tube and thus both secures the spindle nut 13 against rotation and guides the spindle nut 13 in the guide tube 2.

[0028] A front most part of the spindle nut 13b is provided with external threads for mounting of the tubular activation element 3, which in a rearmost end is provided with corresponding internal threads, such that the activation element can be screwed onto the spindle nut 13. In the front end of the guide tube 2 there is a guide bushing 14 as guide for the tubular adjustment element 3, just as the guide bushing 14 can be designed with a seal to prevent ingress of dust and moisture between the guide bushing 4 and the tubular adjustment element 3. The seal can be an O-ring, lip seal or the like.

[0029] For mounting of the guide tube 2 to the front end of the chassis 7 a tubular mounting bushing 15 is secured to the rear end of the guide tube. The outer diameter of the guide tube 2 and the inner diameter of the mounting bushing 15 is adapted to each other such that the guide tube 2 with a fixed fit protrudes into the mounting bushing 15, such that possible transversal forces on the guide tube 2 is transferred to the mounting bushing 15. For retaining the guide tube 2 in the axial direction stampings 16 are done from the outer side of the mounting bushing 15 and into the guide tube 2. These stampings 16 are done opposite screw channels 17 in the guide tube 2, such that the deformations are received in the screw channels 14 and thus do not protrude into the rest of the hollow of the guide tube, such that they do not prevent or somehow affect the movement of the spindle nut and the tubular adjustment element 3.

[0030] The rear end of the mounting bushing 15 is designed with a radially protruding flange 18 containing screw holes 19 with internal threads. The mounting bushing 15 with mounted tubular adjustment element 3 is secured with the rear mounting 4 around the chassis 7 in that screws 20 are led from the rear mounting 4 through the chassis 7 to the screw holes 19 in the mounting bushing 15 for the guide tube 2, by which the rear mounting 4 and the mounting bushing 15 are tightened around the chassis 7. For increasing the stability between the flange 18 and the rear of the mounting bushing 15 deep drawn slanting support sections 21 can be provided.

[0031] FIG. 9-11 show how the electric motor 6 is mounted in the chassis 7. Thus, the chassis 7 comprises a mounting surface 22 with two through-going holes 23,24 and a lock hole 25. The front end of the electric motor 6 comprises a flange 26 with two screw holes 27,28 having internal threads and a flap 29, which in this shown embodiment is hinge-shaped. The flap 29 is prepared for engagement with a side of the lock hole 25 in the mounting surface 22 of the chassis 7. For mounting the electric motor 6 in the chassis 7 the worm 12a of the electric motor is led into a shaft hole 30 in the chassis 7. Simultaneously, the hinge-shaped flap 29 is led into the lock hole 25 in the mounting surface 22.

[0032] Subsequently, the electric motor 6 is rotated such that the flap 29 is brought into engagement with a side of the lock hole 25. Thus, the electric motor 6 is fixed to the chassis such that the holes 23,24 in the mounting surface 22 are aligned with the screw holes 27,28. Subsequently, fastening means in the shape of the screws 31,32 are led through the holes 23,24 and are brought into engagement with the threads of the screw holes 27,28 in the flange 26 of the electric motor, by which the electric motor 6 is secured to the chassis 7.

[0033] FIGS. 12 and 13 show an embodiment where the flange 26 on the electric motor 6 further comprises a protrusion 34 in the shape of a collar, pin or the like. The mounting surface 22 on the chassis 7 has a corresponding depression 35 prepared for engagement with the protrusion 34 of the flange. The depression 35 can be of a circular shape or be designed as a groove. The rim area of the depression 35 can with advantage be raised a little compared to the mounting surface and can e.g. be designed as a wedge.

[0034] In this embodiment the electric motor 6 is mounted in the manner described above. When the electric motor 6 is rotated the flap 29 is also here brought into engagement with a side of the lock hole 25. Further, the protrusion 34 on the flange 26 is brought into engagement with the depression 35 on the mounting surface 22. Due to the raised rim area of the depression 35 the assembler will register an auditory or tactile signal when the protrusion 34 passes the rim area of the depression 35. Thus, the protrusion 34 and the depression 35 function as a snap lock. Subsequently, the protrusion 34 enters into engagement with the depression 35 thus contributing to an easier mounting and an improved fixation of the electric motor 6 in the chassis 7 before these are secured to each other by means of the screws 31,32.

[0035] From FIGS. 9-13 it appears that the electric motor 6 comprises a gasket 33 in the shape of a rubber ring for dampening of the vibrations from the electric motor 6.