Steering system for a motor vehicle

Abstract

The invention relates to a steering system (1) of a motor vehicle, comprising: a steering gear (2) operated with a hydraulic medium; a first hydraulic pump (4) driven by the first electric motor (3) for providing main oil supply to the steering gear (2); and the second hydraulic pump (6) is driven by the second motor (5) and is used for providing emergency oil supply for the steering gear (2).

Description

Technical Field

[0001] The invention relates to a steering system of a motor vehicle and a method for operating such a steering system. Background Art

[0002] Patent document DE 10 2015 109 508 A1 discloses such a steering system for a motor vehicle.

[0003] It is common practice, and in some cases a legal requirement, to provide redundancy for the hydraulic pump unit in such electrohydraulic steering systems. According to the state of the art, this is usually achieved by driving the hydraulic pump with a dual winding electric motor so that if one winding fails, the motor can run with the other winding.

[0004] Another common implementation method is to use two motors of the same specifications.

[0005] The second winding increases the length and cross-section of the motor, which results in relatively large motor dimensions, exacerbating the already difficult installation situation in the vehicle. In addition, the complexity of existing solutions is quite high, with particular problems in using the same set of motors and hydraulic pumps in different vehicles and in achieving an ideal design for the application (magnetic circuit, dimensions, lightweight construction, etc.).

[0006] Another disadvantage of existing solutions is that protection mechanisms such as electromagnetic compatibility must be designed for two drivers (ie, two windings), which often leads to increased solution complexity. Summary of the invention

[0007] In view of the above, an object of the present invention is to provide a steering system for a motor vehicle, which can provide a high degree of safety and requires only a small installation space.

[0008] In order to achieve the above-mentioned objective, the present invention provides a brake disc according to the technical solution of the present application.

[0009] According to the invention, the steering system has a steering gear operated by a hydraulic medium, a first hydraulic pump driven by a first electric motor for providing a main oil supply to the steering gear, and a second hydraulic pump driven by a second electric motor for providing an emergency oil supply to the steering gear.

[0010] Compared with the existing solutions, the steering system of the present invention uses two electric motors and two hydraulic pumps, but each of the electric motors only needs to have one winding, and if the first electric motor fails, the second electric motor can be used. As a result, the size of the two electric motors is much smaller than that of the electric motors used in the existing solutions, which can also reduce the size of the electric hydraulic pump unit and the entire electric hydraulic steering system.

[0011] Specifically, the second electric motor as well as the first electric motor can have extremely small structural dimensions, thereby significantly increasing the flexibility of their installation positions. Advantageously, a technically and commercially very advantageous standard motor can be used as the second electric motor.

[0012] Another significant advantage of the technical solution of the present invention is that both electric motors and both hydraulic pumps can be optimized for their respective application purposes, thereby achieving increased efficiency throughout their entire life cycle. In addition, the technical solution of the present invention can also achieve the unification, standardization and coordination of the process chain, so that the process chain can be standardized according to a modular strategy and can be used for different vehicles.

[0013] A further advantage of the solution of the invention compared to the prior art is that if the first hydraulic pump fails, the second hydraulic pump can take over the function of the first hydraulic pump, at least in the sense of providing an emergency oil supply to the steering gear, which is not available in current solutions with only one hydraulic pump. The second electric motor and the second hydraulic pump therefore represent a redundant solution for the first electric motor and the first hydraulic pump.

[0014] A very advantageous improvement of the invention can provide that the power of the first electric motor is greater than the power of the second electric motor and the geometric delivery volume of the first hydraulic pump is greater than the geometric delivery volume of the second hydraulic pump. By adapting the electric motor and the hydraulic pump to their respective intended uses, the structural dimensions of the electric motor and the hydraulic pump can be further reduced.

[0015] In order to ensure that the second motor provides sufficient power, it is also provided that the second motor operates within a high voltage range.

[0016] In this regard, if the second motor is operated in the low voltage range, the second motor can be significantly smaller in size and can be powered by a different power source than the first motor. This also enables the use of an application-optimized motor that combines technical and commercial advantages.

[0017] In another advantageous improvement of the present invention, the first motor and the second motor are provided with a common controller, so that the operation of the two motors can be controlled in a less complicated and simplified manner.

[0018] In another advantageous technical solution of the present invention, the second hydraulic pump can be used as a backup support for the first hydraulic pump. In this way, in the special case where the steering gear requires extra high hydraulic support, two hydraulic pumps can be used to provide this support, wherein the second hydraulic pump is responsible for providing the boost.

[0019] In another advantageous technical solution of the present invention, it can be provided that the second hydraulic pump can be used to cool the battery of the motor vehicle. This represents an alternative use of the second hydraulic pump, which not only brings added value to the motor vehicle, but also allows the second hydraulic pump to be used rationally without the second hydraulic pump supplying oil to the steering gear.

[0020] Additionally or alternatively, the second hydraulic pump can be used to supply oil to the motor vehicle transmission, which is also the case.

[0021] In another advantageous technical solution of the present invention, in order to be able to use the second hydraulic pump very simply to achieve its corresponding intended purpose, a valve can be provided for switching the oil supply to the steering gear, battery and / or hydraulic system through the second hydraulic pump.

[0022] The technical solution of the present invention also proposes an operating method of the above-mentioned steering device.

[0023] The steering gear is supplied with hydraulic medium mainly by the first hydraulic pump in normal operation, and by the second hydraulic pump in emergency operation.

[0024] In this way, the steering system according to the invention can be operated particularly advantageously. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following is a description of the principles of the embodiments of the present invention in conjunction with the accompanying drawings.

[0026] Figure 1 A simplified schematic diagram of the steering system of the present invention is shown. DETAILED DESCRIPTION

[0027] Figure 1 A steering system 1 of a motor vehicle (not shown) is shown. The motor vehicle is in particular a commercial vehicle, such as a truck, a construction site vehicle, a bus, etc. The steering system 1 has a steering gear 2 which is configured as an electrohydraulic steering gear and can be operated in a known manner. The individual components and functions of the steering gear 2 are in principle known and therefore will not be described in detail here.

[0028] The steering system 1 also has a first hydraulic pump 4 driven by the first electric motor 3 and a second hydraulic pump 6 driven by the second electric motor 5. The first hydraulic pump 4 is used to provide a main oil supply for the steering gear 2. For this purpose, a hydraulic line 4a leads from the first hydraulic pump 4 to the steering gear 2. On the other hand, the second hydraulic pump 6 is used to provide an emergency oil supply for the steering gear 2. The term "main supply" refers to the normal operation of the steering gear 2, such as the normal situation when the motor vehicle is running. The term "emergency supply" refers to the situation where the steering gear 2 still needs to operate when, for example, the first electric motor 3 and / or the first hydraulic pump 4 fails. During the emergency operation of the steering gear 2, for example, it may occur that the steering force increases, the steering angle decreases, etc. Therefore, the second electric motor 5 and the second hydraulic pump 6 represent a redundant solution for the first electric motor 3 and the first hydraulic pump 4. In addition to the emergency supply, the second hydraulic pump 6 can also be used as a backup support for the first hydraulic pump 4, for example, when the motor vehicle requires an extra-high level of steering support.

[0029] from Figure 1 It can be seen that the first motor 3 and the first hydraulic pump 4 are both larger than the second motor 5 and the second hydraulic pump 6. In addition, the power of the first motor 3 is greater than the power of the second motor 5, and the geometric delivery volume of the first hydraulic pump 4 is greater than the geometric delivery volume of the second hydraulic pump 6. Therefore, the two motors 3 and 5 and the two hydraulic pumps 4 and 6 are suitable for their respective application purposes. In addition, the first motor 3 can be operated in a high voltage range (for example, from 350 volts to 1000 volts), and the second motor 5 can be operated in a low voltage range (for example, from 12 volts to 48 volts). For example, the first motor 3 can be powered by the traction battery of an electric vehicle, and the second motor 5 can be powered by the starting battery. However, voltages other than the above voltages may also work, and the two motors 3 and 5 can also be operated at the same voltage. For example, the second motor 5 is also suitable for a high voltage solution.

[0030] The first hydraulic pump 4 is directly connected to the first electric motor 3, for example, in such a way that the output shaft of the electric motor 3 also serves as the drive shaft of the first hydraulic pump 4, which is configured as a vane pump, for example. In a similar manner, the second hydraulic pump 6 is also directly connected to the second electric motor 5. The various connections described above can be made in a known manner. In this case, the second electric motor 5 is also attached to the housing of the first electric motor 3. However, for reasons of installation space, for example, the second electric motor 5 connected to the second hydraulic pump 6 can also be attached to a different position on the motor vehicle than the first electric motor 3 connected to the first hydraulic pump 4.

[0031] Figure 1 A controller 7 is also shown to jointly control the first motor 3 and the second motor 5. The second motor 5 and the second hydraulic pump 6 it operates can be used completely independently of the first motor 3 and the first hydraulic pump 4 it operates. The controller 7 can also be physically connected to the first motor 3 and / or the second motor 5.

[0032] The delivery volumes generated by the two hydraulic pumps 4 and 6 depend on their geometric delivery volumes and speeds, so that controlling the respective electric motor 3 or 5 simultaneously includes controlling the respective hydraulic pump 4 or 6 .

[0033] Figure 1 A valve 8 is also shown, to which a hydraulic line 6a leads from the second hydraulic pump 6. The valve 8 is used to switch the oil supply to the steering gear 2, the battery 9 of the motor vehicle and / or the gearbox 10 of the motor vehicle via the second hydraulic pump 6. For this purpose, corresponding hydraulic lines lead from the valve 8 to the steering gear 2, the battery 9 and the gearbox 10. The second hydraulic pump 6 can thus be used to cool the battery 9 and / or the gearbox 10 of the motor vehicle. In principle, it is also conceivable to use the second hydraulic pump 6 for other non-steering applications.

Claims

1. A steering system (1) for a motor vehicle, characterized in that: A steering gear (2) operated by a hydraulic medium; a first hydraulic pump (4) driven by a first electric motor (3) for providing a main oil supply to the steering gear (2); A second hydraulic pump (6) driven by a second electric motor (5) is used to provide emergency oil supply to the steering gear (2).

2. The steering system according to claim 1, characterized in that: The power of the first electric motor (3) is greater than the power of the second electric motor (5); the geometric delivery volume of the first hydraulic pump (4) is greater than the geometric delivery volume of the second hydraulic pump (6).

3. The steering system according to claim 1 or 2, characterized in that: The first electric motor (3) operates in a high voltage range.

4. The steering system according to claim 1, 2 or 3, characterized in that: The second electric motor (5) operates in a low voltage range.

5. The steering system according to any one of claims 1 to 4, characterized in that: The first motor (3) and the second motor (5) are provided with a common controller (7).

6. The steering system according to any one of claims 1 to 5, characterized in that: The second hydraulic pump (6) serves as a backup for the first hydraulic pump (4).

7. The steering system according to any one of claims 1 to 6, characterized in that: The second hydraulic pump (6) is used to cool a battery (9) of the motor vehicle.

8. The steering system according to any one of claims 1 to 7, characterized in that: The second hydraulic pump (6) is used to supply oil to a gearbox (10) of the motor vehicle.

9. The steering system according to claim 7 or 8, characterized in that: The valve (8) is configured to switch the oil supply to the steering gear (2), the battery (9) and / or the gearbox (10) through the second hydraulic pump (6).

10. An operating method of a steering system according to any one of claims 1 to 9, characterized in that: During normal operation, the first hydraulic pump (4) mainly supplies hydraulic medium to the steering gear (2), while during emergency operation, the second hydraulic pump (6) supplies hydraulic medium to the steering gear (2).

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