Tension output type electric power steering gear suitable for commercial vehicle and working method of tension output type electric power steering gear

Abstract

The invention relates to a tension output type electric power steering gear suitable for a commercial vehicle and a working method thereof.The steering gear comprises a driving motor, a shell assembly, a turbine, a worm, a lead screw and a screw and nut assembly, and the steering gear judges the motion state of the vehicle according to a signal sent by a steering wheel torque sensor through a main controller; and the steering execution assembly is further controlled, so that the steering motor controls the steering wheels to rotate, and the steering intention of the driver is met. According to the steering gear, assistance is provided through the motor, a mechanical linkage device is omitted, a relatively more flexible arrangement mode can be adopted, meanwhile, large output torque can be borne and transmitted, the transmission efficiency is high, and meanwhile sufficient hardness and abrasion resistance are achieved.

Description

Technical Field

[0001] The invention relates to the field of motor vehicle power-driven steering gears, and in particular to a tension output type electric power steering gear suitable for commercial vehicles and a working method thereof. Background Art

[0002] The electric power steering system appeared in the late 1980s. With the rapid development of electronic technology, the electric power steering system, as a representative of mechatronics, combines motors with electronic devices. While satisfying the driver's need for easy operation and applicability, it also improves the sense of the road and has a positive improvement on the driving system of the car. The rack-and-pinion electric power steering gear conforms to the current trend of energy saving and environmental protection in the world, and now basically replaces the rack-and-pinion hydraulic power steering gear on passenger cars. The existing column-type electric power steering gear and the circulating ball screw-type electric power steering gear cannot withstand and transmit large output torque, so the electric circulating ball can only stop at the level of less than 2000Nm output torque. However, for commercial vehicles with large tonnage and large tonnage trucks, the existing electric power steering system with large torque output still has the problems of high power consumption and high steering requirements. Summary of the invention

[0003] In order to solve the technical problems existing in the prior art, the present invention provides a tension output type electric power steering device suitable for commercial vehicles and a working method thereof.

[0004] In the motion transformation and transmission of the commercial vehicle steering system, the steering gear rocker arm shaft outputs a swinging motion. When the rocker arm shaft outputs a torque of 8000Nm, the pulling force output by the rocker arm ball pin end is 32000N. If a recirculating ball screw structure is used (the middle diameter of the ball screw pair is 30mm, and the pitch is 15mm), the nut is axially fixed and only rotates, and the ball screw moves linearly. The ball screw generates a pulling force of 35000N, then less than 200Nm is needed to rotate the nut, the power of the power-assisting motor is not more than 1.5Kw, and the motor speed is not more than 1200rpm.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A tension output electric power steering device suitable for commercial vehicles comprises a drive motor, a housing assembly, a ball screw, a screw nut assembly and two sets of worm gears, wherein the drive motor is drivingly connected to one set of worm gears, the other set of worm gears is connected to the screw nut assembly, the screw nut assembly is connected to the ball screw, and the ball screw, the screw nut assembly and the two sets of worm gears are all arranged in the housing assembly.

[0007] As a preferred technical solution, the housing assembly includes a housing, a sub-housing, a sub-housing end cover, and a housing end cover. The housing and the sub-housing are respectively located at both ends of the steering gear. The housing is fixedly connected to the sub-housing through a nut, the housing end cover is fixed to the housing through screws, the housing end cover is fixedly connected to the housing, and the sub-housing end cover is fixedly connected to the sub-housing through an oil seal.

[0008] As a preferred technical solution, a torque sensor, an input shaft, a torsion bar and multiple deep groove ball bearings are installed in the shell. A group of turbine worm gears connected to the screw and nut assembly include a first turbine and a first worm gear that mesh with each other. The input shaft passes through the shell end cover and is coaxially arranged and fixedly connected to the torsion bar below. The torsion bar is connected to the first worm gear through two cylindrical pins. Both ends of the first worm gear are constrained by deep groove ball bearings. The outer ring of the deep groove ball bearing is fixedly connected to the shell. The torque sensor is connected to the torsion bar, and the outer shell of the torque sensor is fixed in the shell.

[0009] As a preferred technical solution, the first turbine and the first worm are in contact with the ball screw and also with the screw nut assembly.

[0010] As a preferred technical solution, the steering gear also includes an electronic control unit, the torque sensor is connected to the electronic control unit via a signal, and the electronic control unit is electrically connected to the drive motor.

[0011] As a preferred technical solution, the screw-nut assembly includes a guide tube, a guide tube clamp, a steering screw, a steering nut, a steel ball group and two angular contact bearings. The steering nut is installed on the steering screw. The two sides of the steering nut are constrained by two angular contact bearings. The outer ring of the angular contact bearing is fixedly connected to the housing. The guide tube and the guide tube clamp are connected to the steering nut. The steel ball group is arranged in the steering nut. The first turbine is fixedly connected to the steering nut. The steering screw is installed in the sub-housing through a guide sleeve.

[0012] As a preferred technical solution, a group of worm gears connected to the drive motor includes a second worm gear and a second worm gear that mesh with each other, the second worm gear is vertically arranged, the drive motor is transmission-connected to the bottom end of the second worm gear, the first worm gear, the steering screw gear and the second worm gear are coaxially arranged, and the first worm gear and the second worm gear are both fixed on the steering screw gear.

[0013] As a preferred technical solution, a working method suitable for a tension output electric power steering device for commercial vehicles includes the following steps: the steering gear simultaneously inputs torque through the steering wheel and the drive motor, the steering wheel transmits the torque signal to the torque sensor, the sensor receives and sends the signal to the electronic control unit, the electronic control unit processes the signal and controls the start of the drive motor, the drive motor receives the signal from the on-board computer and provides power assistance, the steering nut is driven to rotate through two sets of worm gears, and the steering nut drives the ball screw to provide tension.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The electric power steering device of the present invention, which is suitable for commercial vehicles, has the advantages of flexible layout and high transmission efficiency. The steering tie rod is directly driven by the output of the motor to generate a large steering assist. At the same time, since the electric power steering device does not rely on the engine and has no hydraulic oil pipe, it is not sensitive to cold weather and can work even at minus 40 degrees, so it provides a fast cold start. Because the steering device does not need to be preheated at startup, energy can be saved. In the case of not using a hydraulic oil pump, the parasitic energy loss of the engine is avoided, the fuel economy is improved, and various needs of the steering device of a large vehicle can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the internal structure of a tension output type electric power steering device suitable for commercial vehicles of the present invention;

[0017] Figure 2 It is a front view of the electric power steering device with pulling force output suitable for commercial vehicles of the present invention;

[0018] Figure 3 It is a front view of the electric power steering device with pulling force output suitable for commercial vehicles of the present invention without the housing, the auxiliary housing and the guide sleeve;

[0019] Figure 4 This is a front view of a screw and nut assembly of a tension output type electric power steering device for commercial vehicles according to the present invention;

[0020] Figure 5 AA sectional view of the electric power steering device with pulling force output suitable for commercial vehicles of the present invention;

[0021] Figure 6 It is a BB-direction cross-sectional view of the electric power steering device with pulling force output suitable for commercial vehicles of the present invention;

[0022] Figure 7 It is a partial cross-sectional view of the front view of the electric power steering device of the tension output type applicable to commercial vehicles of the present invention.

[0023] In the figure: 1. housing; 2. auxiliary housing; 3. auxiliary housing end cover; 4. guide sleeve; 5. housing end cover; 6. drive motor; 7. locking nut; 8. angular contact bearing; 9. deep groove ball bearing; 10. oil seal; 11. input shaft; 12. torque sensor; 13. torsion bar; 14. cylindrical pin; 15. screw-nut assembly; 16. first worm; 17. first turbine; 18. second worm; 19. second turbine; 20. screw; 21. steering nut; 22. ball screw; 23. steering screw. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below in conjunction with specific implementation methods:

[0025] like Figure 1 As shown, a tension output electric power steering device suitable for commercial vehicles includes a drive motor 6, a housing assembly, a ball screw 22, a screw nut assembly 15 and two sets of worm gears. The drive motor 6 is connected to one set of worm gears by transmission, the other set of worm gears is connected to the screw nut assembly 15, the screw nut assembly 15 is connected to the ball screw 22, and the ball screw 22, the screw nut assembly 15 and the two sets of worm gears are all arranged in the housing assembly.

[0026] The names and quantities of the parts of the electric power steering system with pull output for commercial vehicles of the present invention are shown in Table 1 below:

[0027] Table 1

[0028]

[0029]

[0030] like Figure 2 As shown, the housing assembly includes a housing 1, a sub-housing 2, a sub-housing end cover 3, and a housing end cover 5. The housing 1 and the sub-housing 2 are respectively located at both ends of the steering gear. The housing 1 is fixedly connected to the sub-housing 2 through a locking nut 7. The housing end cover 5 is fixed to the housing 1 through a screw 20. The housing end cover 5 is fixedly connected to the housing 1, as shown in FIG. Figure 7 As shown, the auxiliary housing end cover 3 is fixedly connected to the auxiliary housing 2 via an oil seal 10 .

[0031] like Figure 6 As shown, a torque sensor 12, an input shaft 11, a torsion bar 13 and a plurality of deep groove ball bearings 9 are installed in the housing 1. A group of turbine worms connected to the screw-nut assembly 15 include a first turbine 17 and a first worm 16 meshing with each other. The input shaft 11 passes through the housing end cover 5 and is coaxially arranged and fixedly connected to the torsion bar 13 below. The torsion bar 13 is connected to the first worm 16 through two cylindrical pins 14. Both ends of the first worm 16 are constrained by deep groove ball bearings 9. The outer ring of the deep groove ball bearings 9 is fixed in the housing 1. The torque sensor 12 is connected to the torsion bar 13, and the outer shell of the torque sensor 12 is fixed in the housing 1.

[0032] like Figure 3 As shown, the first turbine 17 and the first worm 16 are in contact with the ball screw 22 and the screw nut assembly 15 to better adapt to the steering and return use when the output torque is large.

[0033] The steering gear also includes an electronic control unit. The torque sensor 12 is connected to the electronic control unit via a signal, and the electronic control unit is electrically connected to the drive motor.

[0034] like Figure 4 As shown, the screw-nut assembly 15 includes a conduit, a conduit clamp, a steering screw 23, a steering nut 21, a steel ball group and two angular contact bearings 8. The steering nut 21 is installed on the steering screw 23. The two sides of the steering nut 21 are constrained by two angular contact bearings 8. The outer ring of the angular contact bearing 8 is fixedly connected to the housing 1. The conduit and the conduit clamp are connected to the steering nut 21. The steel ball group is arranged in the steering nut 21. The first turbine 17 is fixedly connected to the steering nut 21. The steering screw 23 is installed in the auxiliary housing 2 through a guide sleeve 4.

[0035] like Figure 5 As shown, a group of worm gears connected to the drive motor includes a second worm gear 19 and a second worm gear 18 that mesh with each other. The second worm gear 18 is vertically arranged, and the drive motor is transmission-connected to the bottom end of the second worm gear 18. The first worm gear 17, the steering screw 23 and the second worm gear 19 are coaxially arranged, and the first worm gear 17 and the second worm gear 19 are both fixed on the steering screw 23.

[0036] A working method for a tension output type electric power steering device for commercial vehicles, comprising the following steps: the steering device simultaneously inputs torque through a steering wheel and a drive motor, the steering wheel transmits a torque signal to a torque sensor 12, the torque sensor 12 receives and processes the signal and sends it to an electronic control unit, and then the electronic control unit controls the drive motor to receive a vehicle-mounted computer signal and provide assistance, and drives a steering nut 21 to rotate through two sets of worm gears, and the steering nut 21 drives a ball screw 22 to provide tension.

[0037] The steering gear is based on a circulating ball screw 22 and a worm gear, and eliminates the mechanical linkage device, thereby obtaining a more flexible arrangement, which has the possibility and practical need of being applied to commercial vehicles and large-tonnage heavy trucks.

[0038] The steering of the rotator does not rely on the engine, the hydraulic oil pipe is eliminated, and it is not sensitive to extremely cold weather. Therefore, there is no need for system startup preheating. While saving energy, it also avoids parasitic energy loss generated by the engine without using a hydraulic oil pump and improves fuel economy.

[0039] The torque sensor 12 connected to the steering shaft continuously measures the torque signal on the steering shaft as the steering wheel is manipulated, so that the signal and the vehicle speed signal are simultaneously input to the electronic control unit. The electronic control unit determines the magnitude and direction of the power-assist torque according to the input signal, that is, determines the magnitude and direction of the electric motor current, and adjusts the magnitude of the steering auxiliary power. The electric motor is equipped with an electromagnetic clutch, and the power output by the motor is loaded on the steering tie rod mechanism of the car, so that a steering force adapted to the working conditions of the car is obtained. That is, the electronic control unit determines the rotation direction and the optimal power-assist torque of the motor according to the signal output by the sensor 12, sends a control signal to the motor and the clutch, connects the circuit to control the rotation of the drive motor, adopts a worm gear to reduce the input torque, and adopts a ball screw 22 structure to increase the transmission efficiency of the system. Since it eliminates the mechanical linkage device, a more flexible layout is obtained, which has the possibility and practical demand of being applied to large special vehicles.

[0040] This embodiment is only a further explanation of the invention rather than a limitation of the invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as they are within the scope of the claims of the invention, they are protected by the patent law.

Claims

1. A tension output electric power steering device suitable for commercial vehicles, characterized in that: It includes a driving motor, a housing assembly, a ball screw, a screw-nut assembly and two sets of worm gears. The driving motor is connected to one set of worm gears by transmission, the other set of worm gears is connected to the screw-nut assembly, the screw-nut assembly is connected to the ball screw, and the ball screw, the screw-nut assembly and the two sets of worm gears are all arranged in the housing assembly.

2. The electric power steering device for pulling force output suitable for commercial vehicles according to claim 1, characterized in that: The housing assembly includes a housing, a sub-housing, a sub-housing end cover, and a housing end cover. The housing and the sub-housing are respectively located at two ends of the steering gear. The housing is fixedly connected to the sub-housing through a nut, the housing end cover is fixed to the housing through screws, the housing end cover is fixedly connected to the housing, and the sub-housing end cover is fixedly connected to the sub-housing through an oil seal.

3. The electric power steering device with pull output for commercial vehicles according to claim 2, characterized in that: A torque sensor, an input shaft, a torsion bar and a plurality of deep groove ball bearings are installed in the housing. A group of turbine worm gears connected to the screw-nut assembly includes a first turbine and a first worm gear that mesh with each other. The input shaft passes through the housing end cover and is coaxially arranged and fixedly connected to the torsion bar below. The torsion bar is connected to the first worm gear through two cylindrical pins. Both ends of the first worm gear are constrained by deep groove ball bearings. The outer ring of the deep groove ball bearing is fixedly connected to the housing. The torque sensor is connected to the torsion bar. The outer shell of the torque sensor is fixed in the housing.

4. The electric power steering device for pulling force output suitable for commercial vehicles according to claim 3, characterized in that: The first turbine and the first worm are in contact with the ball screw and also in contact with the screw nut assembly.

5. The electric power steering device with pulling force output suitable for commercial vehicles according to claim 3, characterized in that: The steering gear further comprises an electronic control unit, the torque sensor is connected to the electronic control unit via a signal, and the electronic control unit is electrically connected to the drive motor.

6. The electric power steering device with pulling force output suitable for commercial vehicles according to claim 3, characterized in that: The screw-nut assembly includes a conduit, a conduit clamp, a steering screw, a steering nut, a steel ball group and two angular contact bearings. The steering nut is installed on the steering screw. The two sides of the steering nut are constrained by two angular contact bearings. The outer ring of the angular contact bearing is fixedly connected to the housing. The conduit and the conduit clamp are connected to the steering nut. The steel ball group is arranged in the steering nut. The first turbine is fixedly connected to the steering nut. The steering screw is installed in the auxiliary housing through a guide sleeve.

7. The electric power steering device with pulling force output suitable for commercial vehicles according to claim 6, characterized in that: A group of worm gears connected to the drive motor includes a second worm gear and a second worm gear that mesh with each other. The second worm gear is vertically arranged, and the drive motor is transmission-connected to the bottom end of the second worm gear. The first worm gear, the steering screw gear and the second worm gear are coaxially arranged, and the first worm gear and the second worm gear are both fixed on the steering screw gear.

8. A working method for a tension output type electric power steering device for commercial vehicles according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: the steering gear simultaneously inputs torque through the steering wheel and the drive motor, the steering wheel transmits the torque signal to the torque sensor, the sensor receives and sends the signal to the electronic control unit, the electronic control unit processes the signal and controls the drive motor to start, the drive motor receives the on-board computer signal and provides power assistance, drives the steering nut to rotate through two sets of worm gears, and the steering nut drives the ball screw to provide pulling force.

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