Electromechanically drivable brake pressure generator

Abstract

The invention relates to an electromechanically drivable brake pressure generator for a hydraulic brake system of a vehicle. The electromechanically drivable brake pressure generator comprises an electric motor (18) for generating a drive speed; a planetary gear transmission (22) which is driven by the electric motor (18) on the input side for reducing the drive speed to a low speed; and a hydraulic module (30) which is connected to the planetary gear transmission (22) on the output side for generating brake pressure. The planetary gear transmission (22) has a multi-stage planetary gear (46) which is connected to a sun gear (38) of the planetary gear transmission (22) on the input side and to a driven component (58, 66) of the planetary gear transmission (22) on the output side.

Description

Technical Field

[0001] The invention relates to an electromechanically drivable brake pressure generator for a hydraulic brake system of a vehicle and to a vehicle comprising such an electromechanically drivable brake pressure generator. Background Art

[0002] In order to brake a motor vehicle, the driver's pedal force is usually insufficient, so the motor vehicle is usually equipped with a brake booster. Conventional brake boosters usually work with the negative pressure generated by the internal combustion engine. Here, the pressure difference between the engine pressure and the ambient pressure is used to apply boost as an addition to the driver's pedal force.

[0003] For future motor vehicle drive concepts, alternative brake pressure generating devices are required, since there is no longer a negative pressure to operate conventional vacuum boosters. For this purpose, electromechanical brake pressure generators of interest have been developed.

[0004] Here, the actuating force is generated by means of an electric motor, which controls the movement of a hydraulic piston via a transmission mechanism to generate brake pressure. This type of electromechanical brake pressure generator can be used not only to provide auxiliary force, but also in brake-by-wire systems to simply provide the actuating force. Electromechanical brake pressure generators are therefore particularly advantageous in automated driving.

[0005] An electromechanical brake booster is known from WO 2012 / 013314 A2, which amplifies the pedal force introduced by a ball screw. For this purpose, a recirculating ball nut is arranged on the ball screw, and the recirculating ball nut is driven by an electric motor via a planetary gear mechanism for amplifying the pedal force. Summary of the invention

[0006] The present invention provides an electromechanically drivable brake pressure generator for a hydraulic brake system of a vehicle. The electromechanically drivable brake pressure generator comprises: an electric motor for generating a driving speed; a planetary gear transmission mechanism, which is driven by the electric motor on the input side for reducing the driving speed to a low speed; and a hydraulic module, which is connected to the planetary gear transmission mechanism on the output side for generating brake pressure. Here, the planetary gear transmission mechanism has a multi-stage planetary gear, which is connected to the sun gear of the planetary gear transmission mechanism on the input side and to the driven component of the planetary gear transmission mechanism on the output side.

[0007] A hydraulic module in the sense of the invention is understood to be a module which converts the rotational movement of a planetary gear into a movement of a hydraulic piston in order to generate a brake pressure for an electromechanical brake pressure generator. This is preferably formed by a spindle-nut assembly, by which the rotational movement is converted into a translational movement of the hydraulic piston in the hydraulic cylinder.

[0008] In this case, planetary gears have the advantage that high transmission ratios can be achieved while reducing the installation space due to the high power density. In addition, planetary gears have a low noise profile. Due to the rotational freedom of the transmission elements, sun gear, planetary gear, planetary gear carrier and ring gear, planetary gears offer large clearances in terms of design and transmission ratios. In addition, the distance between the motor axis and the hydraulic axis of the hydraulic piston is reduced by the planetary gear.

[0009] A multi-stage planetary gear is a planetary gear with at least two different toothings, the pitch diameters of which are different from each other. Here, the toothing is arranged in a certain section of the multi-stage planetary gear. Here, the multi-stage planetary gear can be constructed in one piece or in multiple pieces. A planetary gear transmission with a multi-stage planetary gear also has the advantage that the number of components can be reduced. In addition, a multi-stage planetary gear offers the advantage that the volume of such a transmission is smaller than an alternative solution with a similar overall transmission ratio.

[0010] In a preferred embodiment of the present invention, the driven component is a planetary gear carrier that accommodates multi-stage planetary gears. In an alternative embodiment of the present invention, the driven component is a hollow wheel of a planetary gear transmission mechanism. In order to realize the rotational movement of the planetary gear carrier, the hollow wheel is fixed. Accordingly, in an alternative embodiment, the planetary gear carrier is fixed. Compared with the drive through the hollow wheel, a higher transmission ratio is achieved when the drive is through the planetary gear carrier. When the desired transmission ratio is smaller, it is more advantageous to drive through the hollow wheel. As a result, a planetary gear transmission mechanism can be realized with different transmission ratios by small changes.

[0011] Preferably, the multi-stage planetary gear has a bearing region, by means of which the multi-stage planetary gear is supported in a borehole of the planetary gear carrier. The bearing region is a region of the multi-stage planetary gear which is preferably arranged between the toothing regions. Particularly preferably, the material of the bearing region and / or the borehole is designed such that it has lubricating properties. As a result, rolling bearings can be omitted.

[0012] By supporting the multi-stage planetary gears in the bores of the planetary gear carrier, no other components are required, so that the overall height of the planetary gear mechanism can be reduced. In addition, by supporting between the toothed areas, an advantageous central load dissipation is achieved, so that the bending moments acting on the planetary gear carrier can be reduced.

[0013] In an advantageous development, the multi-stage planetary gear is supported on the electric motor or the housing part via a planetary gear shaft. For this purpose, the planetary gear shaft is fixedly connected to the electric motor or the housing part. Due to this support, no additional planetary gear carrier is required for support. As a result, the multi-stage planetary gear can be supported simply and economically. By eliminating the additional planetary gear carrier and the bearing area, installation space can be saved, so that the electromechanical brake pressure generator is more compact.

[0014] Advantageously, the driven component is supported by a bearing arranged between the housing part and the driven component. Here, the bearing is preferably a rolling bearing. Thus, no additional components for support are required, thereby reducing the number of components and reducing the required structural space.

[0015] In a further advantageous embodiment, the driven component is designed as a spur gear. The spur gear can be connected to the driven component in a rotationally fixed manner or can be designed integrally with the driven component. As a result, no further components that may have to be supported are required between the planetary gear mechanism and the hydraulic module. As a result, the distance between the planetary gear mechanism and the hydraulic module can be reduced in a space-saving manner. In addition, the transmission ratio is increased by such a spur gear.

[0016] According to an expedient embodiment, the multi-step planetary gear and / or the sun gear is made of a sintered metal material. The sintered metal material has the advantage that the lubricant can be better provided through the porous surface, thereby minimizing the wear of the components.

[0017] According to another advantageous embodiment, the multi-stage planetary gear and / or the planetary gear carrier and / or the ring gear are made of plastic injection molding material. Plastic injection molding material has the advantage that it is light and can be easily manufactured in a variety of shapes. In addition, the cost of plastic is low, so that the brake pressure generator can be manufactured economically as a whole. In the case of a corresponding selection of plastic, a plastic with good friction properties can also be selected.

[0018] In order to improve the load-bearing capacity and the distribution of the bearing loads, metal inserts are preferably introduced into the plastic material. As a result, the load-bearing capacity of the corresponding components can be improved economically. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Exemplary embodiments of the invention are shown in the drawings and are explained in detail in the following description.

[0020] Figure 1 A schematic diagram showing an exemplary embodiment of a drive train of an electromechanical brake pressure generator according to the invention is shown.

[0021] Figure 2 A first exemplary embodiment of a planetary gear mechanism of an electromechanical brake pressure generator according to the invention is shown, and

[0022] Figure 3 A second exemplary embodiment of a planetary gear mechanism of an electromechanical brake pressure generator according to the invention is shown. DETAILED DESCRIPTION

[0023] exist Figure 1 1 shows a schematic diagram of an exemplary embodiment of a drive train 14 of an electromechanical brake pressure generator according to the invention. The drive train 14 comprises an electric motor 18, by means of which a drive speed can be generated. The electric motor 18 is mechanically connected to the input side of a planetary gear mechanism 22. In this exemplary embodiment, the planetary gear mechanism 22 is positioned coaxially with respect to the motor axis 26. The planetary gear mechanism 22 is additionally arranged on a housing part 28 of the brake pressure generator, which can be, for example, a valve housing.

[0024] The drive speed of the electric motor 18 is reduced to a slower speed by the planetary gear mechanism 22. The planetary gear mechanism 22 is mechanically connected to a hydraulic module 30 at the output side. The hydraulic module 30 can have a brake pressure piston, which can be moved in the axial direction via the spindle-nut assembly to generate brake pressure. The drive train 14 shown in this embodiment is arranged as a two-axis, which means that the hydraulic module 30 is arranged parallel to the motor axis 26.

[0025] Figure 2 A first embodiment of a planetary gear 22 of an electromechanical brake pressure generator according to the invention is shown. The planetary gear 22 is connected to the electric motor 18 via a motor shaft 34. A sun gear 38 is arranged on one end of the motor shaft 34 in a rotationally fixed manner and can rotate together with the motor shaft 34. The sun gear 38 is in direct mechanical meshing with the first toothing regions 42 of a plurality of multi-stage planetary gears 46.

[0026] In this embodiment, the multi-step planetary gear 46 has a bearing region 50, which directly adjoins the first toothing region 46 and by which the multi-step planetary gear 46 is rotatably supported in a corresponding bore 54 of a planetary gear carrier 58. As a result, no additional shaft is required for supporting the multi-step planetary gear 46. In this embodiment, the bearing region 50 and / or the bore 54 are made of a material having a lubricating effect. As a result, no additional rolling or sliding bearing is required for supporting the multi-step planetary gear 46.

[0027] The second toothing region 62 is arranged directly adjacent to the bearing region 50 and has a smaller diameter than the first toothing region 42. Furthermore, the second toothing region 62 has a smaller diameter than the bearing region 50. This ensures that the multi-step planetary gear 46 is assembled in the bore 54. It is also ensured that the inner wall of the bore 54 does not rest against the second toothing region 62.

[0028] The second toothing region 62 meshes directly with an internal gear 66 on which the internal gearing is formed. Here, the internal gear 66 is connected in a rotationally fixed manner to a housing part 28, which can be, for example, a valve housing of a brake pressure generator.

[0029] The planet carrier 58 is mounted relative to the housing part 28. A bearing 74 is arranged between the planet carrier 58 and the housing part 28, by means of which the planet carrier 58 can rotate relative to the housing part 28. In order to mount the planet carrier 58 directly relative to the housing part 28, the planet carrier 58 in this exemplary embodiment has a planet carrier component 78, which is partially embedded in the planet carrier 58. The bearing loads can be absorbed and distributed by the planet carrier component 78.

[0030] In this embodiment, the planetary carrier 58 is configured as a driven component. For this purpose, the planetary carrier 58 has a spur gear 82 , via which the planetary carrier is mechanically connected to the hydraulic module 30 .

[0031] exist Figure 3 In FIG. 2 , a second embodiment of a planetary gear mechanism 22 of an electromechanical brake pressure generator according to the invention is shown. Figure 2 In contrast to the first exemplary embodiment shown in , the multi-stage planetary gear 46 is rotatably supported via a planetary gear shaft 86. The planetary gear shaft 86 is fixedly connected to the housing part 28. In addition, the multi-stage planetary gear 46 does not have a bearing area 50. In this exemplary embodiment, the second toothing area 62 directly adjoins the larger first toothing area 46.

[0032] The internal gear 66 has an internal toothing which meshes with the second toothing region 62 of the multi-stage planetary gear 46. In this exemplary embodiment, the internal gear 66 is rotatably supported relative to the housing part 28 via a bearing 74. In order to directly support the internal gear 66 relative to the housing part 28, the internal gear 66 in this exemplary embodiment has an internal gear component 90 which is partially embedded in the internal gear 66. The bearing loads can be absorbed and distributed by the internal gear component 90.

[0033] In contrast to the first embodiment, in this embodiment, the internal gear 66 is configured as a driven component. For this purpose, the internal gear 66 has a spur gear 82, via which the internal gear is mechanically connected to the hydraulic module 30.

Claims

1. An electromechanically drivable brake pressure generator for a hydraulic brake system of a vehicle, comprising: - an electric motor (18) for generating a driving speed; a planetary gear mechanism (22) which is driven on the input side by the electric motor (18) for reducing the drive speed to a lower speed; and a hydraulic module (30), to which the planetary gear mechanism (22) is connected on the output side for generating a brake pressure, characterized in that: The planetary gear mechanism (22) has a multi-stage planetary gear (46), which is connected to the sun gear (38) of the planetary gear mechanism (22) on the input side and to the driven component (58, 66) of the planetary gear mechanism (22) on the output side, wherein the multi-stage planetary gear (46) has a bearing area (50) through which the multi-stage planetary gear is supported in a bore (54) of a planetary gear carrier (58).

2. The electromechanically drivable brake pressure generator according to claim 1, characterized in that The driven component is a planetary gear carrier (58) that accommodates a plurality of planetary gears (46).

3. The electromechanically drivable brake pressure generator according to claim 1, characterized in that The multi-stage planetary gear (46) is supported on the electric motor (18) or the housing part (28) via a planetary gear shaft (86).

4. The electromechanically drivable brake pressure generator according to claim 1, characterized in that The driven assembly (58, 66) is supported by a bearing (74) disposed between the housing member (28) and the driven assembly (58, 66).

5. The electromechanically drivable brake pressure generator according to claim 1, characterized in that The driven assembly (58, 66) is configured as a spur gear (82).

6. The electromechanically drivable brake pressure generator according to claim 1, characterized in that The multi-stage planetary gear (46) and / or the sun gear (38) are made of sintered metal material.

7. The electromechanically drivable brake pressure generator according to claim 1, characterized in that The multi-stage planetary gear (46) and / or the planetary gear carrier (58) are made of plastic injection molding material.

8. An electromechanically drivable brake pressure generator for a hydraulic brake system of a vehicle, comprising: - an electric motor (18) for generating a driving speed; a planetary gear mechanism (22) which is driven on the input side by the electric motor (18) for reducing the drive speed to a lower speed; and a hydraulic module (30), to which the planetary gear mechanism (22) is connected on the output side for generating a brake pressure, characterized in that: The planetary gear mechanism (22) comprises a multi-stage planetary gear (46), which is connected to the sun gear (38) of the planetary gear mechanism (22) on the input side and to a driven component (58, 66) of the planetary gear mechanism (22) on the output side, wherein the driven component is an internal gear (66) of the planetary gear mechanism (22), wherein the internal gear (66) comprises an internal gear toothing which meshes with a toothing area of ​​the multi-stage planetary gear (46), wherein, in order to directly support the internal gear (66) relative to a housing part (28), the internal gear (66) comprises an internal gear component (90) which is partially embedded in the internal gear (66).

9. The electromechanically drivable brake pressure generator according to claim 8, characterized in that The multi-step planetary gear (46) and / or the ring gear (66) are made of plastic injection molding material. 10 . A vehicle comprising an electromechanically drivable brake pressure generator according to claim 1 .

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