ACTUATOR OF A STEER-BY-WIRE STEERING DEVICE OF A MOTOR VEHICLE AND METHOD FOR ASSEMBLING AN ACTUATOR OF A STEER-BY-WIRE STEERING DEVICE

Abstract

An actuator (10) of a steer-by-wire steering device of a motor vehicle comprises a housing (46, 146), a spindle (42, 142) and a positionally fixed spindle nut (43, 143) mounted so that it can rotate, which within the housing (46, 146) form a spindle drive (41, 141) for the axial displacement of the spindle (42, 142) relative to the spindle nut. An inertial mass (100, 300, 400, 400a, 500, 600) is at least indirectly coupled to the spindle (142), taking into account the oscillation behavior of at least one component of the actuator (10), in particular the spindle (142).

Claims

1. An actuator (10) of a steer-by-sire steering device of a motor vehicle, comprising: a housing (46); a spindle drive (41, 141) with a spindle (42, 142) and a positionally fixed spindle nut (43, 143) rotatably mounted within the housing (46, 146) for the axial displacement of the spindle (42, 142) relative to the spindle nut (43, 143); and an inertial mass (100) coupled to the spindle (142) at least indirectly, the inertial mass (100, 300, 400, 400a, 500, 600) being designed taking into account oscillation behavior of at least one component of the actuator (10).

2. The actuator according to claim 1, wherein the inertial mass (100, 300, 400, 400a, 500, 600) is configured to have a mass moment of inertia which is a function of the oscillation behavior of the spindle (142).

3. The actuator according to claim 1, wherein the inertial mass (100, 300, 400, 400a, 500, 600) consists of a single part or a plurality of parts.

4. The actuator according to claim 3, wherein the inertial mass (100, 300, 400, 400a, 500, 600) is coupled to the spindle (142) by friction and/or in a material-bonded manner and/or in an interlocking manner.

5. The actuator according to claim 1, wherein the inertial mass (100, 300, 400, 400a, 500, 600) has an outer wall (105) concentric with a longitudinal axis (a) of the spindle (142), the said outer wall being cylindrical in order to form a bearing surface which co-operates at least indirectly with the housing (146) and/or with a bearing bush (151).

6. The actuator according to claim 1, wherein when the spindle (142) is coupled to a bearing sleeve (150), and wherein the inertial mass (100, 300, 400, 400a, 500, 600) is at least partially surrounded by the bearing sleeve (150) or the bearing sleeve (150) is at least partially surrounded by the inertial mass (100).

7. The actuator according to claim 6, wherein an outer diameter (T) of the inertial mass (100, 300, 400, 400a, 500, 600) is smaller than or equal to an outer diameter (L) of the bearing sleeve (150).

8. The actuator according to claim 1, wherein the inertial mass (400a) is formed at least in part by a stud (160), which also serves to prevent the spindle (142) from rotating relative to the housing (146).

9. The actuator according to claim 1, wherein the inertial mass (600) is configured as a connecting component between the spindle (142) and the bearing sleeve (150).

10-11. (canceled)

12. A method for assembling the actuator (10) of claim 1, comprising coupling the inertial mass (100, 300, 400, 400a, 500, 600) to the spindle (142) in a plurality of steps.

13. The method of claim 12, wherein the plurality of steps includes a first step of coupling the inertial mass (100, 300, 400, 400a, 500, 600) to the spindle (142) using a screw connection.

14. The method of claim 12, wherein the plurality of steps includes a first step of coupling the inertial mass (100, 300, 400, 400a, 500, 600) to the spindle (142) using or a press-fit connection.

15. The method according to claim 12, comprising: making the inertial mass (100, 300) in at least two parts consisting of a supporting component (100t, 300t) and at least one mass component (100m, 300m); coupling the supporting component (100t, 300t) to the spindle (142); and fitting, subsequently, the mass component (100m, 300m) onto the supporting component (100t, 300t).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Below, the invention is described with reference to preferred embodiments illustrated in the drawing, which shows:

[0025] FIG. 1: An actuator according to the prior art, and

[0026] FIG. 2: A detailed view of the spindle drive of an actuator with an inertial mass

[0027] FIGS. 3 to 6: Further designs of spindle drives for an actuator with an inertial mass, shown in detail in each case.

DETAILED DESCRIPTION

[0028] FIG. 1 shows an actuator 10 for a steer-by-wire steering device, according to the known prior art. The actuator 10 is also called a servomotor and comprises a spindle drive 41, which consists of a spindle 42 having a spindle thread 42a and a spindle nut 43 having a nut thread 43a. The spindle nut 43 is mounted to rotate by virtue of roller bearings 44, 45 in a housing 46 and is axially fixed—in other words its location is fixed. The housing 46 is divided into housing components, namely a housing component 46a on the right, a housing component 46b on the left and a housing component 46c in the middle. A belt wheel 47 is arranged rotationally fixed on the spindle 42, which wheel can be driven via a belt drive 48 by an electric motor 49 by way of a belt 55. At one end the spindle 42 is connected to a bearing sleeve 50 in the form of a push-on or screw-on socket, which is guided on the housing side in a bearing bush in the form of a slide bearing or a thrust bearing 51. The bearing sleeve 50, part of which projects out of the housing component 46b, is connected to a joint sleeve 52 by which a steering linkage (not shown) is articulated to a wheel carrier. The housing component 46a on the right is supported by a joint 53 on the vehicle side or to the structure of the vehicle body.

[0029] The above arrangement can be used as a steer-by-wire steering device on a vehicle axle, preferably a rear-axle steering of a motor vehicle. The actuator 10 illustrated is designed as an individual actuator, i.e. it is for example arranged close to a wheel and supported on the vehicle body on one side in order to change a wheel steering angle of one wheel. At the other end the actuator is connected by way of the joint sleeve 52, via a steering linkage or directly, to a wheel carrier on which a wheel is fitted and able to rotate. The actuator 10 acts, for example, on a rear wheel and changes its wheel steering angle when the spindle 42 is displaced. Correspondingly, a further individual actuator is provided for the second rear wheel. The wheel steering angle is changed by means of the spindle 42, which can be displaced axially when the spindle nut 43 is driven, and the linear movement is transmitted to the joint sleeve 52 via the bearing sleeve 50. The spindle drive described can also be used with a dual or central actuator, i.e. an actuator that has a steering action upon both wheels of an axle.

[0030] In the rest of the figure descriptions the same components with the same functions are given the same indexes.

[0031] FIG. 2 shows a perspective view of a spindle drive of an actuator according to the invention, here depicted so as to show its parts. The spindle 142, together with the spindle nut 143, forms a movement thread. The spindle nut 143 is surrounded by the belt wheel 147, so that when the belt 155 is actuated the spindle nut 143 rotates. As indicated by the double arrow, the spindle 142 can thereby be moved axially in one direction or the other. At its left-hand end the spindle 142 is screwed onto a bearing sleeve 150. The bearing sleeve 150 extends as far as the inertial mass 100 and for that reason is shown partially by broken lines as transparent. The inertial mass 100 is made of two parts and consists of a supporting component 100t and a mass component 100m. The supporting component 100t is in the form of a screw ring and is held by friction onto the thread of the spindle 142. The mass component 100m is made of two half-rings clamped onto the supporting component 100t by screws 104. It can be seen that the outer diameter T of the mass component 100m is larger than the outer diameter L of the bearing sleeve 150. However, the outer diameter of the supporting component 100t is equal to the outer diameter L of the bearing sleeve 150. Thus, during the fitting of the spindle to the bearing sleeve 150 and the housing (not shown here) assembly is easy without the large outer diameter T of the mass component 100m being able to impede the process. The inertial mass can be designed in accordance with the application case, i.e. depending on the amount of damping or oscillation reduction desired. In a simple manner a mass component loom with a larger diameter or a larger axial length can be used. In such cases the same supporting component 100t can be used for various configurations. This provides an inexpensive possibility for improving the oscillation behavior of the spindle or actuator in such manner that acoustically perceptible effects due to the spindle drive or the actuator as a whole are avoided.

[0032] FIG. 3 shows a partially sectioned detailed view of a spindle drive as in FIG. 2. This shows a further variant of an inertial mass 300, which also consists of a supporting component 300t in contact with the spindle 142 and a mass component 300m surrounding the supporting component 300t. The spindle 142 is coupled to the bearing sleeve 150 by screwing. It can be seen that the spindle 142 is first fitted to the supporting component 300t. In the next step the bearing sleeve 150 is screwed onto the end of the spindle 142. Further assembly steps can now follow in order to assemble the spindle drive or actuator. In a further assembly step, the mass component 300m can finally be joined to the supporting component 300t. In the variant shown in FIG. 3 the supporting component 300t and the mass component 300m have shoulders, steps or cut-outs or recesses 115 which enable simple, interlocking assembly. For example, the components can be joined to one another in a cohesive manner by adhesive bonding.

[0033] FIGS. 4 and 4a show a further spindle drive with an inertial mass 400, which in this case is joined to the spindle 142 by a press-fit connection 110. The inertial mass 400, 400a is made in one piece in FIG. 4 and in two pieces in FIG. 4a. In both versions the inertial mass 400, 400a has a cylindrical outer wall 105. In the variant (inertial mass 400a) according to FIG. 4a, a stud 160 is screwed into the outer wall 105 transversely to the longitudinal axis. The stud 160 is on the one hand an anti-rotation feature which is supported against the inside wall of the housing 146 and prevents the spindle 142 from co-rotating when the spindle nut (not shown here) is rotated. On the other hand, the stud is part of the inertial mass 105. At its end the spindle 142 is screwed to the bearing sleeve 150 and is mounted in and guided relative to the housing 146 by the bearing bush 151.

[0034] In both of the versions of FIGS. 4 and 4a the outer diameter T of the outer wall 105 of the inertial mass 400, 400a is slightly smaller compared with the outer diameter L of the bearing sleeve 150, so the outer wall 105 cannot serve as a bearing surface for the bearing bush 151. Furthermore, the inertial mass 400, 400a has a recess 115 at its end on the left. With this recess 115 the inertial mass 400, 400a surrounds the step 152 on the right-hand side of the bearing sleeve 150. It can be seen that by virtue of this nested variant, a configuration of the bearing sleeve 150 and the inertial mass 400 or 400a which is compact as regards the axial and radial extensions is obtained. In contrast to the variants according to FIG. 2 or 3, the desired mass of the inertial mass 400 or 400a can again be varied by a corresponding axial extension. Thus, the inertial mass can even be made with a relatively small diameter.

[0035] FIG. 5 shows a variant similar to FIG. 4 which has been adapted further to give a still more compact structure. The nesting of the one-piece inertial mass 500 and the bearing sleeve 150 is designed as in the variant according to FIG. 4. However, the outer diameters L and T are made equal. The outer wall 105 of the inertial mass 500 is a smooth cylinder, so that it at the same time forms a sliding surface in addition to the sliding surface on the outer wall of the bearing sleeve 150. Thus, the bearing sleeve can be made shorter and the slide-bearing surface required is still present, or indeed the slide-bearing surface can be made larger thanks to this arrangement.

[0036] FIG. 6 shows a further example embodiment of a spindle 142 with an inertial mass 600, which again has a damping action on the spindle. The spindle 142 has a longitudinal axis a and is in part surrounded by an inertial mass 600 to which it is connected in a rotationally fixed manner. The spindle 142 is coupled directly to the bearing sleeve 150 by the inertial mass 600. The inertial mass 600 forms a connecting piece to the bearing sleeve 150. The bearing sleeve 150 holds the end of the spindle 142 and the inertial mass 600 is held in a blind hole or recess 155. The inertial mass 600 has an outer diameter Ti which is smaller than the inside diameter D of the bearing sleeve 150. Between the outer wall 105 of the inertial mass 600 and the inside wall 153 of the bearing sleeve 150 there is an all-round sleeve-like gap 102. Over part of the length of the inertial mass 600 an elastomer 110 with a damping action is provided, which connects the inertial mass 60 elastically with the bearing sleeve 150.

INDEXES

[0037] 10 Actuator [0038] 41 Spindle drive, movement thread [0039] 42, 142 Spindle [0040] 42a Internal thread of the spindle nut [0041] 43, 143 Spindle nut [0042] 43a External thread of the spindle [0043] 44 Bearing [0044] 45 Bearing [0045] 46, 146 Housing [0046] 47, 147 Belt wheel [0047] 48 Belt drive [0048] 49 Electric motor [0049] 50, 150 Bearing sleeve [0050] 51, 151 Bearing bush [0051] 52 Joint sleeve [0052] 53 Bearing eye [0053] 55, 155 Belt [0054] 100 Inertial mass [0055] 100t, 300t Supporting component [0056] 100m, 300m Mass component [0057] 102 Gap [0058] 104 Screw [0059] 105 Outer wall [0060] 110 Press-fit connection [0061] 115 Recess [0062] 120 Ring [0063] 152 Step [0064] 153 Inside wall [0065] 160 Stud [0066] 300 Inertial mass [0067] 400 Inertial mass [0068] 400a Inertial mass [0069] 500 Inertial mass [0070] 600 Inertial mass [0071] a Longitudinal axis [0072] T Outer diameter [0073] L Outer diameter [0074] Ti Outer diameter [0075] D Inside diameter