Electromechanical brake pressure generator with a transmission and method for producing a transmission for an electromechanical brake pressure generator

Abstract

The invention relates to an electromechanical brake pressure generator (14) for a hydraulic brake system (10) of a vehicle. The electromechanical brake pressure generator comprises at least one transmission device (38) for transmitting the torque of the electric motor in order to generate brake pressure. The transmission device (38) comprises: a planetary gear carrier (54) for supporting planetary gears; a planetary gear pin (58) connected to the planetary gear carrier (54) and on which the planetary gears are rotatably fixed; and a pinion (66) for transmitting a driving or output torque, the pinion being connected to the planetary gear carrier in a rotationally fixed manner on the side of the planetary gear carrier (54) opposite to the planetary gear pin (58). At least the part of the planetary gear carrier (54) having the planetary gear pin (58) is made of the same material as the planetary gear pin in a material-matching manner.

Description

Technical Field

[0001] The invention relates to an electromechanical brake pressure generator having a transmission according to the features of the preamble of claim 1, a method for producing a transmission of an electromechanical brake pressure generator according to the features of the preamble of claim 8, and a vehicle comprising an electromechanical brake pressure generator according to the features of claim 10. Background Art

[0002] Here, an electromechanical brake pressure generator can also be used as a brake booster, wherein an input brake force is amplified. An electromechanical brake pressure generator or brake booster comprises in particular a transmission for transmitting the torque of an electric motor to generate the brake pressure. For simplicity, only the brake pressure generator is involved below.

[0003] In order to brake a passenger car, the driver's foot force is usually not enough, so passenger cars are usually equipped with brake boosters. Usually, brake boosters work under 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 a boosting force to the piston rod of the piston / cylinder unit in addition to the driver's foot force.

[0004] For future drive concepts of motor vehicles, alternative brake pressure build-up devices are required, since negative pressure is no longer available for operating conventional vacuum brake boosters. For this purpose, electromechanical brake pressure generators of interest here have been developed.

[0005] Here, the actuating force is generated on the piston / cylinder unit by means of an electric motor. Such electromechanical brake pressure generators can be used not only to provide auxiliary forces but also in brake-by-wire systems for the sole provision of actuating forces. Electromechanical brake pressure generators are therefore particularly advantageous in autonomous driving.

[0006] A conventional electromechanical brake booster is known from WO 2017 / 045804 A1, which is shown in FIG. 1 . In contrast, the present invention also relates to an electromechanical brake pressure generator which can apply a braking force independently of the actuation of the brake pedal. The previously known brake booster 1 comprises a spindle nut 2 and an electric motor (not shown), by the operation of which the spindle nut 2 can be set in rotation via a spur gear 3. The spindle nut 2 is in operative engagement with a spindle 4, so that the spindle 4 can be set in a translational movement along its main axis 5 by means of the spindle nut 2 set in rotation. In order to prevent the spindle 4 from rotating due to the rotation of the spindle nut 2, the brake booster 1 has a bearing arrangement 6, to which the spindle 4 is firmly connected.

[0007] The bearing arrangement 6 comprises a support 6a, on the edge of which two sliding bearings 6b are arranged. The sliding bearings 6b run on a tie rod 7, which extends substantially parallel to the spindle axis 5. The spindle 4 can move in the axial direction via the bearing arrangement 6 and is secured against rotation.

[0008] WO 2017 / 089008 A1 discloses a hydraulic vehicle brake system with an electromechanical brake pressure generator, which generates a braking force as an external force generator, wherein a brake cylinder that can be actuated by muscle force serves only as a setpoint value generator for the electromechanical brake pressure generator. The electromechanical brake pressure generator can therefore also be controlled independently of the brake cylinder that can be actuated by muscle force, so that braking can also be performed in the state of automated driving. Summary of the invention

[0009] The invention proposes an electromechanical brake pressure generator for a hydraulic brake system of a vehicle. The electromechanical brake pressure generator comprises at least one transmission device, which is connected to an electric motor and is used to transmit the torque of the electric motor to generate brake pressure. The transmission device comprises: a planetary gear carrier for supporting planetary gears; planetary gear pins, which are connected to the planetary gear carrier and the planetary gears are rotatably fixed on these planetary gear pins; and a pinion for transmitting a driving or driven torque, which is connected to the planetary gear carrier in a rotationally fixed manner on the side of the planetary gear carrier opposite to the planetary gear pins, wherein at least the part of the planetary gear carrier having the planetary gear pins and the planetary gear pins are made of the same material in a material-matching manner.

[0010] As a transmission, a planetary transmission is particularly preferably used. With a planetary transmission in each transmission stage, the required installation space is reduced due to the high power density. Other advantages of a planetary transmission are the achievable transmission ratios and the noise characteristics.

[0011] In conventional planetary gear carrier-pinions, the planetary gear pins are inserted into corresponding recesses on the planetary gear carrier, which requires a large overlap area, while the planetary gear carrier with planetary gear pins is manufactured from one part. As a result, the planetary gear carrier can be designed to be thinner by eliminating the overlap area and, moreover, there are no large tolerances due to the manufacturing precision. The planetary gear carrier with planetary gear pins can thus be manufactured with high precision, for example, with respect to the planetary shafts. In addition, the number of parts and the installation time required for this are reduced.

[0012] The pinion preferably has helical teeth. This improves running smoothness and reduces noise generation, since each pair of teeth meshes and disengages with a continuous transition and the torque is thus transmitted more evenly.

[0013] In a preferred embodiment of the invention, the planet carrier has a shoulder between the planet pin and the pinion, which shoulder forms a bearing point for a component of the transmission. For example, a ball bearing can be placed on this shoulder, via which the component of the transmission is supported relative to the planet carrier. As a result, no further components are required to support the component of the transmission. Thus, a further function is integrated into the planet carrier-pinion, thereby reducing the number of parts and the assembly time for such a transmission.

[0014] In another preferred embodiment of the invention, the pinion is connected to the planet carrier in a materially bonded manner. The planet carrier and the pinion are preferably manufactured together, for example by sintering. This creates a strong connection between the pinion and the planet pin, so that high drive or output torques can be transmitted. Such a planet carrier-pinion has good durability.

[0015] The pinion is preferably designed as a plastic injection-molded part. In this case, a plastic with good tribological properties can be selected for the pinion, so that a self-lubricating plastic can be used, which can save an additional lubricant. In this case, the pinion can be made of PEEK (polyetheretherketone), for example. In addition, plastic is more suitable than many other materials and can be processed more easily by injection molding. In addition, plastic has a lower weight. Therefore, the pinion made of plastic can be designed simply and economically.

[0016] In an advantageous development, at least the part of the planet carrier that forms the planet pins is a sintered part made of metal. Sintering allows a high degree of dimensional accuracy to be achieved. Thus, even more complex components such as the planet carrier with the planet pins can be manufactured as one component in a materially bonded manner. Furthermore, the pinion is preferably manufactured together with the planet carrier and the planet pins as a sintered part. Thus, in particular for the pinion, due to the open surface produced by sintering, this surface can be used as a lubricant reservoir, thereby improving lubrication.

[0017] The planet carrier also advantageously has a component structure made of plastic. The planet carrier is thus made of at least two different materials. The two different materials lie against each other. The different materials are preferably arranged alternately in the planet carrier. Damping can be integrated into the planet carrier by means of a component structure made of plastic, which is more elastic than metal, for example, and has a higher damping. The plastic is preferably a two-component plastic. The plastic is preferably PEEK (polyetheretherketone) or POM (polyoxymethylene).

[0018] The component structures are preferably designed in such a way that the drive train stiffness to be achieved can be set by the damping and elasticity of these structures and the overloads caused by pressure peaks can be reduced. As a result, no additional components, such as mechanical (spring elements), hydraulic (overpressure valves) or software components are required. For this purpose, more suitable components, such as plastics with high damping properties, can be used. As a result, the costs for such an electromechanical brake pressure generator can be reduced.

[0019] In another advantageous embodiment, these component structures are arranged in the area between adjacent planet gear pins. The planet gear carrier thus has these component structures between the areas forming the planet gear pins. As a result, the planet gears rotatably arranged on the planet gear pins are damped, so that the planet gears can run more smoothly and thus with less noise.

[0020] The invention also proposes a method for producing a transmission of an electromechanical brake pressure generator, wherein at least the planetary gear carrier and the planetary gear pins are produced in a material-fitting manner by means of a forming manufacturing process. The planetary gear carrier and the planetary gear pins are thus produced together in one and the same processing step. As a result, the two parts no longer have to be connected to one another. The use of a forming manufacturing process also allows for a great deal of flexibility in terms of shape and surface.

[0021] According to an advantageous embodiment, sintering or injection molding is used as the forming production process. With these production processes, more complex objects can be formed simply and economically. In addition, sintering can improve lubrication through the porous surface. In contrast, in injection molding, plastics with self-lubricating properties can be selected.

[0022] The invention also proposes a vehicle with an electromechanical brake pressure generator for a hydraulic brake system. With such a vehicle, the advantages mentioned for the electromechanical brake pressure generator can be achieved. In a preferred design, the vehicle can be an automated or fully autonomous vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0024] FIG. 1 shows an electromechanical brake booster known from the prior art;

[0025] 2 is a simplified schematic diagram of a hydraulic brake system for a vehicle having an electromechanical brake pressure generator known from the prior art;

[0026] Figure 3 is a perspective view of a first embodiment of a planetary gear carrier-pinion gear,

[0027] Figure 4 is a perspective view of a second embodiment of a planetary gear carrier-pinion, and,

[0028] Figure 5 It is a perspective view of a third embodiment of a planetary gear carrier-pinion. DETAILED DESCRIPTION

[0029] 2 shows a simplified schematic diagram of a hydraulic brake system 10 known from the prior art for a vehicle having an electromechanical brake pressure generator 14. The hydraulic brake system 10 comprises the electromechanical brake pressure generator 14 and a piston / cylinder unit 18. Both the piston / cylinder unit 18 and the electromechanical brake pressure generator 14 are hydraulically connected to a brake hydraulic system 22, which is shown here only as a block.

[0030] The brake hydraulic system 22 is formed by various valves and other components for forming, for example, an electronic stability program (ESP). In order to brake the vehicle, the brake hydraulic system 22 is additionally connected to at least one wheel brake mechanism 26, so that a braking force can be applied to the wheel brake mechanism 26 by corresponding switching of the valves.

[0031] The piston / cylinder unit 18 is actuated by muscle force via a brake pedal 30. In contrast, the braking force of the electromechanical brake pressure generator 14 is generated by an electric motor 34. For this purpose, the electric motor 34 is connected to a transmission 38, for example a planetary transmission, via which a screw transmission 42 is driven. The screw transmission 42 is connected to a hydraulic piston 46 arranged in a hydraulic cylinder 44, so that a brake pressure can be generated.

[0032] Figure 3 2 shows a perspective view of a first embodiment of a planetary gear carrier-pinion 50. The planetary gear carrier-pinion 50 according to the invention can be used in the planetary transmission 38 shown in FIG. 2. The planetary gear carrier-pinion 50 comprises a substantially circular and disk-shaped planetary gear carrier 54. In this embodiment, the planetary gear carrier 54 is composed of sintered metal.

[0033] Planetary gear pins 58 extending in the axial direction are arranged on the planetary gear carrier 54, and these planetary gear pins are constructed in a material-fitting manner with the planetary gear carrier 54. In this embodiment, three planetary gear pins 58 are arranged on the planetary gear carrier 54. A planetary gear (not shown) is rotatably fixed on each of these planetary gear pins 58. The planetary gear carrier 54 also forms a shoulder 62, which is arranged on the side opposite to the planetary gear pins 58. The shoulder 62 is arranged coaxially and has a smaller diameter than the remaining planetary gear carrier 54. The shoulder 62 forms a bearing position for another component of the transmission 38, so that, for example, a ball bearing can be arranged on the shoulder 62.

[0034] Arranged on the shoulder 62 is a pinion 66 oriented in the axial direction and positioned coaxially, which is connected to the planet carrier 54 in a rotationally fixed manner and can be used to transmit a driving or output torque. The shoulder 62 is thus arranged between the pinion 66 and the remaining planet carrier 54. In this embodiment, the pinion 66 is constructed in a materially compatible manner with the shoulder 62 and thus with the planet carrier 54 and has helical teeth 70. In order to be able to place the bearing on the shoulder 62, the outer diameter of the pinion 66 is smaller than the diameter of the shoulder 62. In this embodiment, the entire planet carrier-pinion 50 is therefore designed as a single component, which is produced in the form of a forming manufacturing process, for example by means of sintering.

[0035] Figure 4 A perspective view of a second embodiment of a planetary gear carrier-pinion 50 is shown. Figure 3 The difference of the first embodiment shown in is that the pinion 66 is injected onto the planetary gear carrier 54 by means of an injection molding process. As a result, the planetary gear carrier 54 and the pinion 66 are made of different materials. In order to be able to transmit the driving or output torque, the planetary gear carrier 54 forms a pinion pin 74, on which the pinion 66 is connected to the planetary gear carrier 54 in a form-fitting manner.

[0036] Figure 5 A perspective view of a third embodiment of a planetary gear carrier-pinion 50 is shown in FIG. Figure 3 The difference from the first exemplary embodiment shown in FIG. 1 is that only the part of the planet carrier 54 forming the planet gear pins 58 is made of a common material, so that the planet gear pins 58 are connected to the planet carrier 54 in a materially bonded manner. In this exemplary embodiment, the planet carrier 54 forms a sector 76 in the region of each planet gear pin 58. In order to be able to transmit sufficient loads, this material is a sintered metal here.

[0037] In the region between the sectors 76, the planet carrier 54 is formed of another material. In this exemplary embodiment, the planet carrier 54 has a component structure 78 made of plastic. The plastic is introduced here, for example, by means of injection molding. By means of these elastic component structures 78 with corresponding damping properties, a certain elasticity and damping of the planet carrier-pinion 50 is set, so that the rigidity of the drive train can be adjusted. Overloads caused by pressure peaks can be reduced in this way.

[0038] In this exemplary embodiment, the planet carrier 54 is additionally connected in a materially bonded manner to the shoulder 62 and the pinion 66. The shoulder 62 and the pinion 66 consist of the same material as the planet gear pins 58 and are thus materially connected to them via the corresponding sectors 76. As a result, sufficient drive or output torque can be transmitted to the planet gears arranged on the planet gear pins 58 via the pinion 66 and the corresponding sectors 76.

Claims

1. An electromechanical brake pressure generator (14) for a hydraulic brake system (10) of a vehicle, comprising at least one transmission device (38) connected to an electric motor (34) for transmitting a torque of the electric motor (34) in order to generate brake pressure, in, The transmission device (38) comprises: - a planetary gear carrier (54) for supporting the planetary gears; - a planet gear pin (58), which is connected to the planet gear carrier (54) and on which the planet gear is rotatably fixed; and a pinion (66) for transmitting a driving or output torque, which is connected to the planetary carrier (54) in a rotationally fixed manner on the side of the planetary carrier (54) opposite the planetary gear pin (58), It is characterized in that At least the part of the planetary gear carrier (54) having the planetary gear pin (58) is made of the same material as the planetary gear pin in a material-fitting manner, the planetary gear carrier (54) has a shoulder (62) between the planetary gear pin (58) and the pinion (66), the shoulder forming a bearing point for a component of the transmission (38), the planetary gear carrier (54) is made of sintered metal, the pinion (66) is designed as a plastic injection-molded part, the pinion (66) is injected onto the planetary gear carrier (54) by means of an injection molding process, and the planetary gear carrier (54) forms a pinion pin (74) on which the pinion (66) is connected to the planetary gear carrier (54) in a form-fitting manner.

2. An electromechanical brake pressure generator (14) for a hydraulic brake system (10) of a vehicle, comprising at least one transmission device (38) connected to an electric motor (34) for transmitting the torque of the electric motor (34) in order to generate brake pressure, in, The transmission device (38) comprises: - a planetary gear carrier (54) for supporting the planetary gears; - a planet gear pin (58), which is connected to the planet gear carrier (54) and on which the planet gear is rotatably fixed; and a pinion (66) for transmitting a driving or output torque, which is connected to the planetary carrier (54) in a rotationally fixed manner on the side of the planetary carrier (54) opposite the planetary gear pin (58), It is characterized in that At least the part of the planetary gear carrier (54) having the planetary gear pins (58) is made of the same material as the planetary gear pins, only the part of the planetary gear carrier (54) forming the planetary gear pins (58) is a sintered part made of metal, and the planetary gear carrier (54) additionally has a component structure (78) made of plastic, which is arranged in the area between adjacent planetary gear pins (58).

3. The electromechanical brake pressure generator (14) according to claim 2, It is characterized in that The pinion (66) is connected to the planetary carrier (54) in a materially bonded manner.

4. The electromechanical brake pressure generator (14) according to claim 2, It is characterized in that The pinion (66) is designed as a plastic injection-molded part.

5. The electromechanical brake pressure generator (14) according to claim 1, It is characterized in that The planet carrier (54) additionally has a component structure (78) made of plastic.

6. Electromechanical brake pressure generator (14) according to claim 5, It is characterized in that The component structure (78) is arranged in the region between adjacent planetary gear pins (58).

7. A method for producing a transmission (38) of an electromechanical brake pressure generator (14) according to any of the preceding claims, It is characterized in that At least the planetary gear carrier (54) and the planetary gear pins (58) are produced in a material-locking manner by means of a forming manufacturing process.

8. The method according to claim 7, It is characterized in that As the forming manufacturing process, sintering or injection molding is used.

9. A vehicle comprising an electromechanical brake pressure generator (14) for a hydraulic brake system (10) according to any one of claims 1 to 6.

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