Tension output type electric power steering gear suitable for commercial vehicle

Abstract

The utility model relates to the field of motor vehicle power driving steering gears, and provides a tension output type electric power steering gear suitable for commercial vehicles, which comprises a driving motor, a shell component, a ball screw, a screw nut assembly and two groups of worm gears and worms, the other set of worm and gear is connected with the screw nut assembly, the screw nut assembly is connected with the ball screw, the steering tie rod is directly driven through output of the motor, and large steering assisting power is generated. The equipment has the advantages of flexible arrangement and high transmission efficiency, the steering tie rod is directly driven by the output of the motor to generate large steering power, and meanwhile, the electric power steering gear is not sensitive to cold weather and can work even at minus 40 DEG C due to the fact that the electric power steering gear does not depend on an engine and is not provided with a hydraulic oil pipe, so that the equipment provides rapid cold start.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of motor vehicle power drive steering gear, specifically relates to a kind of suitable for commercial vehicle tension output type electric power steering gear. BACKGROUND

[0002] Electric power steering system appears in the late eighties of last century, with the rapid development of electronic technology, electric power steering system as the representative of mechatronics, motor and electronic device are combined, while meeting the driver's operation light and applicability, improve the grasp of road feeling, to the driving system of car has more positive promotion.Gear rack type electric power steering gear car steering gear it conforms to the trend of energy saving and environmental protection of the world today, now basically replaces the gear rack type hydraulic power steering car steering gear on passenger car.The existing pipe column type electric power steering gear car steering gear and circulating ball screw type electric power steering gear car steering gear cannot bear and transmit large output torque, so electric circulating ball can only stop at the step of output torque less than 2000Nm.However, for the commercial vehicle and large-tonnage truck with large tonnage, the existing high-torque output electric power steering system still has the problems of high power consumption and high steering requirement. SUMMARY

[0003] To solve the technical problems existing in the prior art, the utility model provides a kind of suitable for commercial vehicle tension output type electric power steering gear.

[0004] In the motion conversion and transmission of commercial vehicle steering system, the steering gear rocker arm shaft outputs swing motion, and the output torque of the rocker arm shaft is 8000Nm, the tension of the rocker arm ball pin end is 32000N, if circulating ball ball screw structure (ball screw pair diameter 30mm, pitch 15mm) is used, nut is axially fixed, only rotates, ball screw makes linear motion, ball screw generates 35000N tension, then rotating nut needs less than 200Nm, and the power of power-assisted motor is not greater than 1.5Kw, and the motor speed is not greater than 1200rpm.

[0005] To achieve the above purpose, the technical solution of the utility model is as follows:

[0006] A kind of suitable for commercial vehicle tension output type electric power steering gear, including drive motor, shell assembly, ball screw, screw nut assembly and two groups of worm gears, drive motor is connected with one group of worm gears, another group of worm gears is connected with screw nut assembly, screw nut assembly is connected with ball screw, ball screw, screw nut assembly and two groups of worm gears are all arranged in shell assembly.

[0007] As a preferred technical scheme, the shell assembly comprises a shell, a sub-shell, a sub-shell end cover, a shell end cover, the shell and the sub-shell are respectively located at two ends of the steering gear, the shell is fixedly connected with the sub-shell through a nut, the shell end cover is fixed on the shell through a screw, the shell end cover is fixedly connected with the shell, and the sub-shell end cover is fixedly connected with the sub-shell through an oil seal.

[0008] As a preferred technical scheme, the shell is internally provided with a torque sensor, an input shaft, a torsion bar and a plurality of deep groove ball bearings, a group of worm gears connected with the screw nut assembly comprises a first worm wheel and a first worm that are in mesh with each other, the input shaft is coaxially arranged and fixedly connected with the torsion bar below the shell end cover, the torsion bar is connected with the first worm through two cylindrical pins, the two ends of the first worm are constrained by the deep groove ball bearings, the outer rings of the deep groove ball bearings are fixedly connected with the shell, the torque sensor is connected with the torsion bar, and the shell of the torque sensor is fixed in the shell.

[0009] As a preferred technical scheme, the first worm wheel and the first worm are in contact with the ball screw and the screw nut assembly

[0010] As a preferred technical scheme, the steering gear further comprises an electronic control unit, the torque sensor is connected with the electronic control unit through a signal, and the electronic control unit is electrically connected with the driving motor.

[0011] As a preferred technical scheme, the screw nut assembly comprises a guide pipe, a guide pipe clamp, a steering screw, a steering nut, a steel ball group and two angular contact bearings, the steering nut is arranged on the steering screw, the steering nut is constrained by the two angular contact bearings at two positions, the outer rings of the angular contact bearings are fixedly connected with the shell, the guide pipe and the guide pipe clamp are connected with the steering nut, the steel ball group is arranged in the steering nut, the first worm wheel is fixedly connected with the steering nut, and the steering screw is arranged in the sub-shell through a guide sleeve.

[0012] As a preferred technical scheme, a group of worm gears connected with the driving motor comprises a second worm wheel and a second worm that are in mesh with each other, the second worm is vertically arranged, the driving motor is in transmission connection with the bottom end of the second worm, the first worm wheel, the steering screw and the second worm wheel are coaxially arranged, and the first worm wheel and the second worm wheel are fixedly connected with the steering screw.

[0013] Compared with the prior art, the steering gear has the advantages that:

[0014] The utility model discloses a be applicable to commercial vehicle tensile force output formula electric power steering gear, with flexible arrangement, transmission efficiency high advantage, through the output of motor direct drive steering tie rod, produce big steering assist, simultaneously because electric power steering gear does not rely on engine, does not have hydraulic oil pipe, so to cold weather is not sensitive, even in minus 40 degrees can work, so it provides quick cold start. Because the steering gear does not need to start preheating, can save energy. Without using hydraulic oil pump, avoid the parasitic energy loss of engine, improve fuel economy, can satisfy the need of each aspect of large -scale car steering gear. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the internal structure schematic view of the electric power steering gear of the utility model for commercial vehicle tensile force output formula,

[0016] Figure 2 It is the front view of the electric power steering gear of the utility model for commercial vehicle tensile force output formula,

[0017] Figure 3 It is the front view of the electric power steering gear of the utility model for commercial vehicle tensile force output formula removes the casing and the auxiliary casing and the guide sleeve,

[0018] Figure 4 It is the front view of the screw nut assembly of the electric power steering gear of the utility model for commercial vehicle tensile force output formula,

[0019] Figure 5 It is the A-A cross section view of the electric power steering gear of the utility model for commercial vehicle tensile force output formula,

[0020] Figure 6 It is the B-B cross section view of the electric power steering gear of the utility model for commercial vehicle tensile force output formula,

[0021] Figure 7 It is the partial cross section view of the front view of the electric power steering gear of the utility model for commercial vehicle tensile force output formula.

[0022] In the drawing: 1. casing, 2. auxiliary casing, 3. auxiliary casing end cover, 4. guide sleeve, 5. casing 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 worm wheel, 18. second worm, 19. second worm wheel, 20. screw, 21. steering nut, 22. ball screw, 23. steering screw. DETAILED DESCRIPTION

[0023] The technical solution of this utility model will be further described below with reference to specific embodiments:

[0024] like Figure 1 As shown, an electric power steering system for commercial vehicles with pull output capability includes a drive motor 6, a housing assembly, a ball screw 22, a screw and nut assembly 15, and two sets of worm gears. The drive motor 6 is connected to one set of worm gears, and the other set of worm gears is connected to the screw and nut assembly 15. The screw and nut assembly 15 is connected to the ball screw 22. The ball screw 22, the screw and nut assembly 15, and the two sets of worm gears are all housed within the housing assembly.

[0025] The names and quantities of the parts for the pull-output type electric power steering system of this utility model applicable to commercial vehicles are shown in Table 1 below:

[0026] Table 1

[0027]

[0028] like Figure 2 As shown, the housing assembly includes a housing 1, a secondary housing 2, a secondary housing end cap 3, and a housing end cap 5. Housing 1 and secondary housing 2 are located at opposite ends of the steering gear. Housing 1 is fixedly connected to secondary housing 2 by a lock nut 7. Housing end cap 5 is fixed to housing 1 by screws 20. Housing end cap 5 is fixedly connected to housing 1, as shown in the diagram. Figure 7 As shown, the end cap 3 of the secondary housing is fixedly connected to the secondary housing 2 via an oil seal 10.

[0029] like Figure 6 As shown, a torque sensor 12, an input shaft 11, a torsion bar 13, and multiple deep groove ball bearings 9 are installed inside the housing 1. A set of worm gears connected to the screw and nut assembly 15 includes a first worm gear 17 and a first worm 16 that mesh with each other. The input shaft 11 passes through the housing end cover 5 and is coaxially 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. The two ends of the first worm 16 are constrained by the deep groove ball bearings 9. The outer ring of the deep groove ball bearings 9 is fixed inside 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 inside the housing 1.

[0030] like Figure 3 As shown, the first worm gear 17 and the first worm 16 are in contact with the ball screw 22 and also with the screw and nut assembly 15, in order to better adapt to steering and return to center when the output torque is large.

[0031] The steering system 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.

[0032] like Figure 4As shown, the screw and nut assembly 15 includes a guide tube, a guide tube clamp, a steering screw 23, a steering nut 21, a steel ball assembly, and two angular contact bearings 8. The steering nut 21 is mounted on the steering screw 23. The two sides of the steering nut 21 are constrained by the two angular contact bearings 8. The outer ring of the angular contact bearing 8 is fixedly connected to the housing 1. The guide tube and the guide tube clamp are connected to the steering nut 21. The steel ball assembly is disposed inside the steering nut 21. The first worm gear 17 is fixedly connected to the steering nut 21. The steering screw 23 is mounted in the secondary housing 2 through a guide sleeve 4.

[0033] like Figure 5 As shown, a set of worm gears connected to the drive motor includes a second worm gear 19 and a second worm 18 that mesh with each other. The second worm 18 is arranged vertically, and the drive motor is connected to the bottom end of the second worm 18. The first worm gear 17, the steering screw 23, and the second worm gear 19 are arranged coaxially, and both the first worm gear 17 and the second worm gear 19 are fixed on the steering screw 23.

[0034] The electric power steering system uses a relatively large transmission ratio. Its input torque is input simultaneously through the steering wheel and the motor. The steering wheel transmits the torque signal to the torque sensor 12. The torque sensor 12 receives and processes the signal and sends it to the electronic control unit. The electronic control unit then controls the drive motor to receive the signal from the on-board computer and provide assistance. The steering nut 21 is rotated through two sets of worm gears, and the steering nut 21 drives the ball screw 22 to provide tension.

[0035] The steering gear is based on a circulating ball screw 22 and a worm gear, eliminating the mechanical linkage device, thus achieving a more flexible layout and making it applicable to commercial vehicles and heavy-duty trucks.

[0036] The steering mechanism does not depend on the engine, eliminates hydraulic lines, and is not sensitive to extremely cold weather. Therefore, it does not require system start-up preheating, saving energy and avoiding parasitic energy loss from the engine without using a hydraulic pump, thus improving fuel economy.

[0037] Torque sensor 12, connected to the steering shaft, continuously measures the torque signal on the steering shaft as the steering wheel is operated, and this signal, along with the vehicle speed signal, is simultaneously input to the electronic control unit (ECU). Based on the input signal, the ECU determines the magnitude and direction of the assist torque, i.e., the magnitude and direction of the motor current, and adjusts the steering assist power accordingly. An electromagnetic clutch is mounted on the motor, and the power output from the motor is applied to the vehicle's steering tie rod mechanism, providing a steering force adapted to the vehicle's operating conditions. In other words, the ECU determines the motor's rotation direction and optimal assist torque based on the signal output from sensor 12, sends control signals to the motor and clutch, and activates the circuit to control the drive motor's rotation. A worm gear mechanism is used to reduce the large input torque, while a ball screw structure 22 increases the system's transmission efficiency. Because it eliminates the mechanical linkage, it allows for more flexible layout options, making it suitable for large special vehicles and meeting practical needs.

[0038] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-creative modifications to this embodiment as needed after reading this specification, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A pull-output type electric power steering system suitable for commercial vehicles, characterized in that, It includes a drive motor, a housing assembly, a ball screw, a screw and nut assembly, and two sets of worm gears. The drive motor is connected to one set of worm gears, and the other set of worm gears is connected to the screw and nut assembly. The screw and nut assembly is connected to the ball screw. The ball screw, the screw and nut assembly, and the two sets of worm gears are all housed within the housing assembly. The housing assembly includes a housing, a sub-housing, a sub-housing end cap, and a housing end cap. The housing and the sub-housing are located at both ends of the steering gear. The housing is fixedly connected to the sub-housing by nuts. The housing end cap is fixed to the housing by screws and is fixedly connected to the housing. The sub-housing end cap is fixedly connected to the sub-housing by an oil seal. The housing contains a torque sensor, an input shaft, a torsion bar, and multiple deep groove ball bearings. A set of worm gears connected to the screw and nut assembly includes a first worm gear and a first worm that mesh with each other. The input shaft passes through the housing end cover and is coaxially and fixedly connected to the torsion bar below. The torsion bar is connected to the first worm through two cylindrical pins. The two ends of the first worm 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, and the housing of the torque sensor is fixed inside the housing. The steering system 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; A torque sensor connected to the steering shaft continuously measures the torque signal on the steering shaft as the steering wheel is operated. This signal, along with the vehicle speed signal, is simultaneously input to the electronic control unit. Based on the input signal, the electronic control unit determines the magnitude and direction of the assist torque, that is, the magnitude and direction of the motor current, and adjusts the magnitude of the steering assist power. The motor is equipped with an electromagnetic clutch, and the power output of the motor is applied to the steering tie rod mechanism of the car, so that it obtains a steering force adapted to the car's operating conditions.

2. The electric power steering system for commercial vehicles with pull-output capability as described in claim 1, characterized in that, The first worm gear and the first worm are in contact with the ball screw and also with the screw and nut assembly.

3. The electric power steering system for commercial vehicles with pull-output capability as described in claim 1, characterized in that, The screw and nut assembly includes a guide tube, a guide tube clamp, a steering screw, a steering nut, a steel ball assembly, and two angular contact bearings. The steering nut is mounted on the steering screw, and its two sides are constrained by the two angular contact bearings. The outer rings of the angular contact bearings are fixedly connected to the housing. The guide tube and the guide tube clamp are connected to the steering nut. The steel ball assembly is disposed inside the steering nut. The first worm gear is fixedly connected to the steering nut. The steering screw is mounted in the secondary housing through a guide sleeve.

4. The electric power steering system for commercial vehicles with pull-output capability as described in claim 1, characterized in that, A set of worm gears connected to the drive motor includes a second worm gear and a second worm that mesh with each other. The second worm is arranged vertically. The drive motor is connected to the bottom end of the second worm. The first worm gear, the steering screw, and the second worm gear are arranged coaxially. The first worm gear and the second worm gear are both fixed on the steering screw.

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