Modular electric power steering device

Abstract

A modular electric power steering system includes: a tubular neck (1) for guiding a universal joint (10), wherein the tubular neck (1) has a specific bending angle; a drive assembly (3) consisting of an electric motor controlled by a controller; a transmission assembly (2) consisting of a torque sensor and a transmission mechanism; a rack (4) consisting of a retractable tube; a transmission housing (7, 11) housing the transmission assembly (2); two retractable tubular rack housing halves (5) wherein the transmission housing (7, 11) is arranged between the two rack housing halves (5); and two feet (8) respectively arranged on the outer ends of the two rack housing halves (5), wherein the feet (8) are used to secure the power steering system to a vehicle, wherein the feet (8) include bushings for guiding the rack (4).

Description

Technical Field

[0001] This invention relates to a modular electric power steering system for motor vehicles. Furthermore, this invention relates to a method for manufacturing a modular electric power steering system. Background Technology

[0002] The electric servo steering system uses an electric motor to generate steering support, and the force of the motor is transmitted to the rack through a servo drive mechanism. A torque sensor records steering commands, measures the deflection of the torsion bar connected to the steering system, and transmits the data to the controller.

[0003] In the EPSp, the servo unit is located on the steering pinion. The supporting torque of the electric motor is transmitted via a worm gear transmission mechanism.

[0004] In EPSapa, the motor is parallel to the rack axis, and steering support is transmitted directly to the rack via a belt drive using a ball screw transmission mechanism.

[0005] All components of an electric servo steering system are housed within a steering housing. Developing and supplying steering housings according to customer requirements is extremely complex and expensive. The costly development of steering housings is not worthwhile for small-batch production. Furthermore, it takes several years to develop a new steering housing and bring it to market. However, the market demands that the production of electric servo steering systems must be flexible. Summary of the Invention

[0006] Therefore, the object of this invention is to provide a servo steering device that can be developed inexpensively and in the shortest possible time. It should also serve small customers and small-batch production.

[0007] This objective is achieved by the subject matter of the present invention and the method according to the present invention.

[0008] The idea behind this invention is to divide the servo steering mechanism into separate modules and use as many identical components as possible within them. While these identical components may be too large (e.g., designed for maximum rack force), corresponding component approvals have subsequently been obtained. This significantly reduces development time.

[0009] Flexibility is achieved through the ability to individually shorten and adjust different components. The rack and the two housing halves in which the rack is arranged can therefore be easily shortened to the required length.

[0010] Both rack housing halves are composed of high-strength standard tubing. The rack itself is also made of high-strength standard tubing. After shortening the rack, the toothed components are welded to the tubing for the EPSapa. Alternatively, in the EPSapa, a tubular structural element with a ball screw is inserted into and secured to the rack. Furthermore, the threads for the steering tie rod are cut.

[0011] Furthermore, the bending angle is adjusted within the tubular neck (which guides the universal joint to the intermediate shaft or steering spindle). The tubular neck is used to ensure that the two joints of the universal joint are aligned with each other at the correct angle, thereby reducing universal joint engagement errors.

[0012] The transmission housing is located between the two rack housing halves. The steering transmission mechanism and servo unit are housed within the transmission housing. A motor with a controller is connected to the steering transmission mechanism in the usual manner. All of the above components are identical parts and can be selected from standardized structural kits.

[0013] The so-called support feet are located on the outer ends of the two rack housing halves. Each support foot consists of a tubular section containing a bushing for guiding the rack. The support feet have external protrusions with drilled holes, allowing the steering system to be screwed into the vehicle. During assembly, the support feet are first rotated to the required mounting angle for the steering system. Proper adjustment of the mounting angle is important for reducing universal joint engagement errors at the universal joint. The support feet are then secured to the corresponding rack housing halves. This can be done by pressing, retracting, or welding. Attached Figure Description

[0014] An embodiment is described with reference to the accompanying drawings.

[0015] Figure 1 An exploded view of a modular steering system according to the present invention is shown.

[0016] Figure 2 A perspective view of a modular steering system according to the present invention is shown. Detailed Implementation

[0017] The embodiment is explained using EPSp, in which the servo unit is located on the steering pinion.

[0018] Figure 1 An exploded view of the modular steering system according to the present invention can be seen. The rack 4 is composed of a high-strength standard tube with toothed elements fixed to it. The transmission housing consists of a lower transmission housing 7 and an upper transmission housing 11. A pinion that meshes with the rack 4 is housed in the lower transmission housing 7. Furthermore, a pressure block for pressing the rack onto the pinion is typically provided in the lower transmission housing 7. A helical gear transmission mechanism is housed in the upper transmission housing 11. A drive assembly 3, consisting of an electric motor and a controller, is screwed onto the upper transmission housing 11. The upper transmission housing 11 is closed by a cover 9.

[0019] The transmission mechanism assembly 2 extends through the upper and lower transmission mechanism housings 7 and 11 and consists of a torque sensor, a helical gear, and a pinion.

[0020] The support legs 8 consist of tubular sections with protrusions, each having drilled holes for securing the steering system to the vehicle. They contain bushings for guiding the rack 4 and are fixed to the outer end of the rack housing half 5.

[0021] The tubular neck 1 includes a cross universal joint 10 configured as a synchronous universal joint. The tubular neck 1 is bent and, in addition, rotates along its longitudinal axis during assembly, so that the angle of connection to the intermediate shaft is precisely adjusted.

[0022] Figure 2 The modular steering system according to the invention can be seen in its assembled state through a mid-perspective view. After the components (rack 4, rack housing half 5) are shortened to the required length, these components are first arranged relative to each other. Here, the components (legs 8, tubular neck 1) are rotated to adjust the required crossing and mounting angles. The structural components are then securely connected, for example by pressing or welding.

Claims

1. A modular electric power steering system, comprising: A tubular neck (1) that guides the universal joint (10), wherein the tubular neck (1) has a specific bending angle; A drive assembly (3) consisting of an electric motor, which is controlled by a controller; A transmission mechanism assembly (2) consisting of a torque sensor and a transmission mechanism; The rack (4) is composed of a shortenable tube; The transmission mechanism housing (7, 11) contains the transmission mechanism assembly (2); Two shortenable tubular rack housing halves (5), wherein the transmission mechanism housing (7, 11) is arranged between the two rack housing halves (5); Two feet (8) are respectively arranged on the outer ends of two rack housing halves (5), wherein the feet (8) are used to fix the power steering device to the vehicle, and wherein the feet (8) include bushings for guiding the rack (4).

2. The modular electric power steering device according to claim 1, Its features are, The transmission mechanism of the transmission mechanism assembly (2) is a helical gear transmission mechanism; The rack (4) is composed of a tube, and the toothed components are fixed on the tube; The transmission mechanism housing consists of an upper transmission mechanism housing (11) and a lower transmission mechanism housing (7). A helical gear transmission mechanism is installed in the upper transmission mechanism housing, and a pinion meshes with a rack (4) in the lower transmission mechanism housing.

3. The modular electric power steering device according to claim 1, Its features are, The transmission mechanism of the transmission mechanism assembly (2) consists of a belt transmission mechanism and a ball nut transmission mechanism; The rack (4) is the main spindle of the ball screw.

4. A method for assembling a modular electric power steering device according to claim 1, the method comprising the following steps: Select the transmission mechanism assembly (2), drive assembly (3), transmission mechanism housing (7, 11) and support leg (8) from the standardized structural kit; Adjust the rack (4) to the desired length; Adjust the tubular neck (1) to the desired angle; Adjust the two tubular rack housing halves (5) to the desired length; The modules are arranged and aligned with each other, wherein the legs (8) rotate relative to the rack housing half (5) to adjust the desired installation angle, and wherein the tubular neck (1) rotates along its longitudinal axis to adjust the desired bending angle of the universal joint. The modules are securely assembled by pressing, shrinking and / or welding.

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