Linear actuator

Abstract

A linear actuator for generating a linear actuating force, including a first drive unit having a first drive shaft designed as a hollow shaft, a first rotation-translation transmission driven by the first drive unit, having a first threaded spindle and a first threaded nut engaging with the threaded spindle, wherein the drive shaft of the first drive unit is designed as a first threaded spindle, a second drive unit arranged axially to the first drive unit and having a drive shaft, and a second rotation-translation transmission driven by the second drive unit, having a second threaded spindle and a threaded nut engaging with the second threaded spindle, wherein the drive shaft of the second drive unit is connected to the second threaded spindle; via the hollow shaft in a rotationally fixed manner.

Claims

1. A linear actuator for generating a linear actuating force, comprising: a first motorized drive unit having a first drive shaft formed as a hollow shaft, a first rotation-translation gear driven by the first motorized drive unit and having a first threaded spindle and a first threaded nut in engagement with the threaded spindle, wherein the drive shaft of the first motorized drive unit is configured as the first threaded spindle, a second motorized drive unit arranged axially to the first motorized drive unit and having a drive shaft, and a second rotation-translation gear driven by the second motorized drive unit and having a second threaded spindle and a threaded nut in engagement with the second threaded spindle, wherein the drive shaft of the second motorized drive unit is connected rotationally fixedly to the second threaded spindle via the hollow shaft, a first force transmission element disposed radially outward from the first threaded spindle and coupled thereto, and a second force transmission element disposed radially outward from the second threaded spindle and coupled thereto.

2. The linear actuator as claimed in claim 1, wherein the first threaded nut is connected to the force transmission element, and the second threaded nut is connected to the second force transmission element.

3. The linear actuator as claimed in claim 2, wherein the first and second force transmission elements are configured as hydraulic or pneumatic pistons which cooperate with cylindrical chambers arranged in the hydraulic or pneumatic block and adapted to the hydraulic or pneumatic pistons.

4. The linear actuator as claimed in claim 3, wherein the first and second rotation-translation gears are arranged on opposite sides of the hydraulic or pneumatic block.

5. The linear actuator as claimed in claim 1, wherein the first and second drive units are each configured as an electric motor.

6. The linear actuator as claimed in claim 1, wherein the first and second rotation-translation gears are each formed as a ball-screw drive.

7. The linear actuator as claimed in claim 1, wherein a control unit is assigned to each of the first and second drive units, wherein the control units are configured identically.

8. A linear actuator for generating a linear actuating force, comprising: a first motorized drive unit having a first drive shaft formed as a hollow shaft, a first rotation-translation gear driven by the first motorized drive unit and having a first threaded spindle and a first threaded nut in engagement with the threaded spindle, wherein the drive shaft of the first motorized drive unit is configured as the first threaded spindle, and the first threaded nut is connected to a first force transmission element, a second motorized drive unit arranged axially to the first motorized drive unit and having a drive shaft, and a second rotation-translation gear driven by the second motorized drive unit and having a second threaded spindle and a threaded nut in engagement with the second threaded spindle, wherein the drive shaft of the second motorized drive unit is connected rotationally fixedly to the second threaded spindle via the hollow shaft, and the second threaded nut is connected to a second force transmission element, wherein the first and second force transmission elements cooperate with a hydraulic or pneumatic block to generate a hydraulic or pneumatic pressure.

9. The linear actuator as claimed in claim 8, wherein the first and second rotation-translation gears are arranged on opposite sides of the hydraulic or pneumatic block.

10. The linear actuator as claimed in claim 8, wherein the first and second drive units together with the first rotation-translation gear are arranged in a first housing which is flanged to the hydraulic or pneumatic block.

11. The linear actuator as claimed in claim 8, wherein the second rotation-translation gear is arranged in a second housing which is flanged to the hydraulic or pneumatic block.

12. A linear actuator for generating a linear actuating force, comprising: a first motorized drive unit having a first drive shaft formed as a hollow shaft, a first rotation-translation gear driven by the first motorized drive unit and having a first threaded spindle and a first threaded nut in engagement with the threaded spindle, wherein the drive shaft of the first motorized drive unit is configured as the first threaded spindle, a second motorized drive unit arranged axially to the first motorized drive unit and having a drive shaft, and a second rotation-translation gear driven by the second motorized drive unit and having a second threaded spindle and a threaded nut in engagement with the second threaded spindle, wherein the drive shaft of the second motorized drive unit is connected rotationally fixedly to the second threaded spindle via the hollow shaft, wherein the first threaded nut is at least partially surrounded by the rotor of the first drive unit.

13. The linear actuator as claimed in claim 12, wherein the first and second drive units are each configured as an electric motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below in detail with reference to an exemplary embodiment depicted in the only FIG. 1. This FIG. 1 shows a diagrammatic cross-section view of a linear actuator according to an aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) FIG. 1 shows diagrammatically a hydraulic block 50 of a hydraulic braking system of a vehicle, which comprises cylindrical chambers 51.1, 51.2, 52.1 and 52.2 which, together with the force transmission elements 23.1, 23.2, 43.1 and 43.2 configured as pistons of the linear actuator 1, form a hydraulic piston-cylinder arrangement. Thus FIG. 1 shows a hydraulic linear actuator 1.

(3) This linear actuator 1 comprises, in a first pot-like housing 2, two motorized drive units 10 and 30 configured as brushless electric motors, namely a first electric motor 10 and a second electric motor 30. These two electric motors 10 and 30 are arranged axially directly adjacent, wherein the second electric motor 30 is arranged on the base side of the pot with regard to the first housing 2, and the first hydraulic motor 10 connects thereto in the direction of the hydraulic block 50.

(4) Each of these two electric motors 10 or 30 is constructed from a stator 13 or 33 with associated motor winding 14 or 34, and a rotor 12 or 32. The two rotors 12 and 32 consist of a pot-like sleeve, and on their outer casing surface carry permanent magnets 12.1 and 32.1 arranged at regular angular intervals. To determine the angular positions of the two rotors 12 and 32 required for phase-correct powering of the two stators 13 and 33, a contactless position sensor is provided in each case (not shown in FIG. 1), the signals from which are supplied to a control unit 4 of the first electric motor 10 and to a control unit 5 of the second electric motor 30. Finally, an operating voltage source (not shown) supplies the motor windings 14 and 34 and the control units 4 and 5 with the necessary operating voltage.

(5) The pot-like rotor 32 of the second electric motor 30 points with its opening in the direction of the base part 2.1 of the first housing 2, which has a central bulge which firstly is partly surrounded by the rotor 32 and secondly receives a bearing 31.1 for receiving the drive shaft 31 of the second electric motor 30. This is arranged rotationally fixedly on the drive shaft 31 via a flange of the rotor 32.

(6) This drive shaft 31 is guided through a drive shaft 11, configured as a hollow shaft, of the first electric motor 10. This drive shaft 11 is connected at the end to the rotor 12 of the first electric motor 10, wherein the opening of the pot-like rotor 12 points in the direction of the hydraulic block 50.

(7) A first rotation-translation gear 20, configured as a ball-screw drive, is assigned to the first electric motor 10 and is driven thereby. For this, the drive shaft 11 is configured simultaneously as the first threaded spindle 21 of this rotation-translation gear 20, and guides an axially movable first threaded nut 22 of this rotation-translation gear 20. The end of this first threaded spindle 21 ends in a cylindrical cavity 53 of the hydraulic block 50 where it is guided by means of a bearing 11.1. A further bearing point 11.2 is provided on the opposite end of the hollow shaft 21 and is connected to the rotor 12.

(8) The first threaded nut 22 is configured as a sleeve so that it is surrounded at least partially by the pot-like rotor 12 of the first electric motor 10 when in this region. Furthermore, this threaded nut 22 on the end face has a peripheral flange 22.1 which carries on the edge first force transmission elements 23.1 and 23.2 running in the axial direction and evenly distributed over the periphery.

(9) These first force transmission elements 23.1 and 23.2 are configured as hydraulic pistons and, together with the chambers 51.1 and 51.2, form a piston-cylinder arrangement of the hydraulic block 50. These hydraulic pistons 23.1 and 23.2 are mounted movably in the chambers 51.1 and 51.2, so that the first threaded nut 22 can only move axially on the first threaded spindle 21. If, on corresponding powering of the first electric motor 10, the first threaded nut 22 moves on the first threaded spindle 21 in the direction toward the hydraulic block 50, a hydraulic pressure is built up in the chambers 51.1 and 51.2 of the hydraulic block 50. The seals of the hydraulic pistons 23.1 and 23.2 are designated 23.11 and 23.21.

(10) A second rotation-translation gear 40, also configured as a ball-screw drive, is assigned to the second electric motor 30 and is driven thereby. For this, the drive shaft 31, guided through the hollow shaft 11 configured as the first threaded spindle 21, is connected to a second threaded spindle 41 of the second rotation-translation gear 40, wherein a second threaded nut 42 is arranged axially movably on this second threaded spindle 41.

(11) This second rotation-translation gear 40 is received by a second pot-like housing 3 flanged to the hydraulic block 50 opposite the first housing 2.

(12) The second threaded spindle 41 is configured as a hollow shaft and is mounted rotatably, firstly with one end via a bearing 41.1 arranged on the end face of the second housing 3, and secondly with the other end inside the cylindrical cavity 53 of the hydraulic block 50 by means of a further bearing 41.2. The second threaded spindle 41 is connected at this end rotationally fixedly to the drive shaft 31 of the second electric motor 30 by means of a connecting bearing 31.2.

(13) The second threaded nut 42 is configured as a sleeve, corresponding to the first threaded nut 22, and also has a radially protruding flange 42.1 which carries on its periphery second force transmission elements 43.1 and 43.2 running in the axial direction and evenly distributed over the periphery, and which as hydraulic pistons also cooperate with chambers 52.1 and 52.2 arranged in the hydraulic block 50 as a piston-cylinder arrangement, so that in this way only an axial movement on the second threaded spindle 41 is possible for the second threaded nut 42. If, on corresponding powering of the second electric motor 30, the second threaded nut 42 moves on the first threaded spindle 41 in the direction toward the hydraulic block 50, a hydraulic pressure is built up in the chambers 52.1 and 52.2 of the hydraulic block 50.

(14) In order to ensure an independent functioning firstly of the first hydraulic pistons 23.1 and 23.2 of the first threaded nut 22, cooperating with the chambers 51.1 and 51.2, and secondly of the second hydraulic pistons 43.1 and 43.2 of the second threaded nut 42, cooperating with the chambers 52.1 and 52.2, the hydraulic pistons 23.1 and 23.2 of the first threaded nut 22 arranged in a circle, opposite the hydraulic pistons 43.1 and 43.2 of the second threaded nut 42, are offset to each other and hence also the associated chambers 51.1 and 51.2 or 52.1 and 52.2 in the hydraulic block 50.

(15) The hydraulic block 50 may also be configured as a pneumatic block.

LIST OF REFERENCE NUMERALS

(16) 1 Linear actuator 2 First housing of linear actuator 1 2.1 Base part of first housing 2 3 Second housing of linear actuator 1 4 Control unit of first drive unit 10 5 Control unit of second drive unit 30 10 First motorized drive unit, electric motor 11 Drive shaft of first drive unit 10 12 Rotor of first drive unit 10 12.1 Permanent magnet 13 Stator of first drive unit 10 14 Motor winding of first drive unit 10 20 First rotation-translation gear 21 First threaded spindle of the first rotation-translation gear 20 22 First threaded nut of the first rotation-translation gear 20 22.1 Flange of first threaded nut 22 23.1 First power transmission element, hydraulic piston 23.11 Seal of hydraulic piston 23.1 23.2 First power transmission element, hydraulic piston 23.21 Seal of hydraulic piston 23.2 30 Second motorized drive unit, electric motor 31 Drive shaft of second drive unit 30 31.1 Bearing of drive shaft 31 31.2 Connecting bearing of drive shaft 31 32 Rotor of second drive unit 30 32.1 Permanent magnet 33 Stator of second drive unit 30 34 Motor winding of second drive unit 30 40 Second rotation-translation gear 41 Second threaded spindle of second rotation-translation gear 40 41.1 Bearing of second threaded spindle 41 41.2 Bearing of second threaded spindle 41 42 Second threaded nut of second rotation-translation gear 40 42.1 Flange of second threaded nut 42 43.1 Second power transmission element, hydraulic piston 43.2 Second power transmission element, hydraulic piston 50 Hydraulic or pneumatic block 51.1 Cylindrical chamber of hydraulic or pneumatic block 50 51.2 Cylindrical chamber of hydraulic or pneumatic block 50 52.1 Cylindrical chamber of hydraulic or pneumatic block 50 52.2 Cylindrical chamber of hydraulic or pneumatic block 50 53 Cavity of hydraulic or pneumatic block 50