Drive-by-wire steering gear assembly and control method

Abstract

The invention relates to a drive-by-wire steering gear assembly control method, and belongs to the technical field of automobile steering gears. The assembly comprises a shell, a connecting rod, a ball nut screw pair, a steering motor, a connecting rod anti-rotation mechanism and a connecting rod displacement sensor, axial sliding grooves are evenly distributed in the end of the connecting rod, the connecting rod anti-rotation mechanism is arranged between the axial sliding grooves and the shell, and the connecting rod displacement sensor is arranged beside the connecting rod anti-rotation mechanism. According to the assembly, a gear, a connecting piece, a locking piece and oblique teeth on the rack are omitted, the production cost can be effectively reduced, the machining and assembling links can be effectively reduced, the production efficiency is improved, and the production cost is further reduced. Meanwhile, due to the fact that a gear, a connecting piece and a locking piece are omitted, occupation of the gear, the connecting piece and the locking piece on an engine cabin can be omitted, occupation of the steering gear assembly on the space of the engine cabin can be reduced, and therefore the steering gear assembly can be arranged more conveniently. The problem that an existing drive-by-wire steering gear is high in production cost is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of steer-by-wire steering gear assembly control method, belong to automobile steering gear technical field. BACKGROUND

[0002] Mechanical steering gear is driven rack movement by steering column, intermediate shaft, gear shaft, and is assisted by hydraulic or steering motor. The characteristic that steer-by-wire steering gear is different from mechanical steering gear is that: steer-by-wire steering gear cancels intermediate shaft, and directly controls steering motor rotation through electronic signal from steering wheel, and then drives rack movement through steering motor. Since the intermediate shaft is cancelled, it can effectively reduce the generation cost of steering system, and then reduce the overall vehicle cost. The patent application disclosed in patent No. CN119682836A, steering control method and vehicle, includes a housing, a steering assembly, a self-locking assembly and a controller, the self-locking assembly is connected to the housing and is arranged on the outer peripheral side of the steering assembly, and the self-locking assembly has a locking state and an unlocking state.

[0003] But the above-mentioned steer-by-wire steering gear still includes a gear meshed with the rack and a connecting piece (equivalent to the support seat of the mechanical steering gear), and a locking piece (equivalent to the adjusting nut of the mechanical steering gear), the production and assembly of the above-mentioned components still exist cost, resulting in high cost of the steer-by-wire steering gear. Therefore, it is necessary to design a steer-by-wire steering gear assembly and control method to solve the above problems. SUMMARY

[0004] The purpose of the present application is to provide a kind of steer-by-wire steering gear assembly and control method, which can further reduce production cost, to solve the problem of high production cost of existing steer-by-wire steering gear.

[0005] The technical scheme of the present application is: A kind of steer-by-wire steering gear assembly, it includes housing, connecting rod, ball nut screw pair, steering motor, connecting rod anti-rotation mechanism and connecting rod displacement sensor, connecting rod is inserted on the housing, one end of connecting rod is provided with ball nut screw pair for driving connecting rod movement, steering motor is provided on the outer side of ball nut screw pair, and controller is provided on steering motor;Characterized in that: the other end of connecting rod is circumferentially uniformly distributed with axial slide groove, connecting rod anti-rotation mechanism is arranged between axial slide groove and housing, connecting rod displacement sensor is arranged on the housing between connecting rod anti-rotation mechanism and ball nut screw pair, and connecting rod displacement sensor is electrically connected with controller.

[0006] The connecting rod anti-rotation mechanism is composed of a limiting sleeve, steel balls and a retainer, the inner wall of the limiting sleeve is provided with an axial raceway corresponding to the axial slide groove, the steel balls are uniformly distributed between the axial slide groove and the axial raceway, and the steel balls are connected to each other by the retainer;The limiting sleeve is threadedly connected with the housing.

[0007] The assembly ring slot is arranged on the limiting sleeve at the end of the cage, and the snap spring for limiting the position of the cage is clamped in the assembly ring slot.

[0008] The lock pin is screwed on the shell at one side of the limiting sleeve and is connected with the limiting sleeve in abutment.

[0009] The ball screw nut screw rod pair comprises a screw rod arranged at the end of the connecting rod, a nut sleeved on the screw rod, and balls between the nut and the screw rod.

[0010] A control method of a steer-by-wire steering gear assembly, characterized in that it comprises the following steps: 1) the vehicle-mounted computer obtains the steering signal of the steering wheel and transmits it to the controller of the steer-by-wire steering gear assembly, and the controller calculates the rotation angle and rotation speed of the steering motor according to the steering signal of the steering wheel; 2) the controller controls the rotation of the steering motor according to the calculated rotation angle and rotation speed of the steering motor, the steering motor drives the connecting rod to move a length L1 through the ball screw nut screw rod pair, and then pulls the wheels to deflect through the moving connecting rod; 3) when the connecting rod moves, the moving distance of the connecting rod is detected through the connecting rod displacement sensor; the connecting rod displacement sensor transmits the displacement distance L2 of the connecting rod to the vehicle-mounted computer and the controller, and the vehicle-mounted computer and the controller compare L2 and L1, and when the difference between L1 and L2 is within the set threshold, the steering is completed; 4) when the difference between L1 and L2 exceeds the set threshold, the controller repeats steps 1)-3) for feedback adjustment according to the difference between L1 and L2, until the difference between L1 and L2 is within the set threshold, and the steering is completed.

[0011] When the connecting rod moves, the connecting rod anti-rotation mechanism prevents the connecting rod from rotating.

[0012] The beneficial effects of the present application are: The steer-by-wire steering gear assembly cancels the gear, connecting piece, locking piece and helical teeth on the rack, although the connecting rod anti-rotation mechanism is added, the number of added components is significantly less than the number of canceled components, which can effectively reduce the production cost of the steering gear assembly, and due to the reduction in the number of components, the machining and assembly links of the components in the production process of the steering gear assembly can be effectively reduced, the production efficiency of the steering gear assembly is improved and the production cost is further reduced. At the same time, due to the cancellation of the gear, connecting piece and locking piece, the occupation of the gear, connecting piece and locking piece to the engine compartment can be cancelled, the occupation of the steering gear assembly to the engine compartment space can be reduced, so that the steering gear assembly can be arranged more conveniently. The problem of high production cost of the existing steer-by-wire steering gear is solved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a schematic view of the axis of the present application; Figure 2 is a schematic view of the cross-section of the present application; Figure 3 is a schematic view of the cross-section of the present application; Figure 4 is a schematic view of the longitudinal section of the present application; Figure 5 is a schematic view of the cross-section of the present application; Figure 3 is a schematic view of the cross-section of the present application; Figure 6 is a schematic view of the cross-section of the present application; Figure 7 is a schematic view of the longitudinal section of the present application; Figure 8 is a schematic view of the left side of the present application.

[0014] In the figure: 1, housing, 2, connecting rod, 3, steering motor, 4, connecting rod displacement sensor, 5, controller, 6, axial sliding slot, 7, limiting sleeve, 8, steel ball, 9, retainer, 10, axial raceway, 11, assembly ring groove, 12, circlip, 13, check pin, 14, screw rod, 15, nut, 16, ball bearing. DETAILED DESCRIPTION

[0015] The line control steering gear assembly, it includes the shell 1, connecting rod 2, ball nut screw pair, steering motor 3, connecting rod anti-rotation mechanism and connecting rod displacement sensor 4, the shell 1 is inserted with connecting rod 2, to connect the wheel through the pull rod of the end head of connecting rod 2, and then pull the pull rod in the movement process of connecting rod 2, thereby pulling the wheel deflection, steering.The end head of connecting rod 2 is provided with the ball nut screw pair of driving connecting rod 2 movement, the shell 1 outside the ball nut screw pair is provided with steering motor 3, steering motor 3 is provided with controller 5, and the controller 5 is ECU (Chu Guanjie brand, model RI04X).The function of controller 5 is to control the rotation of steering motor 3 through controller 5, and then control the movement of connecting rod 2 in the movement process of connecting rod 2 driven by steering motor 3 through ball nut screw pair, thereby controlling steering.The other end head of connecting rod 2 is circumferentially distributed with axial slide groove 6, and the axial slide groove 6 is provided with connecting rod anti-rotation mechanism between the shell 1, to prevent the rotation of connecting rod 4 through the cooperation of connecting rod anti-rotation mechanism and axial slide groove 6, and then prevent the rotation of connecting rod 4 with ball nut screw pair, thereby accurately controlling the axial movement of connecting rod 4, thus accurately controlling the deflection of the wheel, and ensuring the steering accuracy.The shell 1 between connecting rod anti-rotation mechanism and ball nut screw pair is provided with connecting rod displacement sensor 4 (model DE30), and the connecting rod displacement sensor 4 is electrically connected with controller 5.The function of connecting rod displacement sensor 4 is to detect the displacement of connecting rod 4 through connecting rod displacement sensor 4 and feedback to controller 5, and then compare the expected value of connecting rod 2 movement (the displacement value of connecting rod 2 when connecting rod 2 movement is only driven by steering motor 3, which is the ideal value) and the actual value of connecting rod 2 movement (the displacement value of connecting rod 2 under the combined action of connecting rod 2 movement driven by steering motor 3 and the reaction force of road surface transmitted to connecting rod through the wheel), thereby feedback adjusting the displacement of connecting rod 2, so that connecting rod 2 reaches the expected value of connecting rod 2 movement, thereby making the movement of connecting rod 2 accurate.

[0016] The anti-rotation mechanism of the connecting rod is composed of a limiting sleeve 7, steel balls 8 and a retainer 9. The inner wall of the limiting sleeve 7 is provided with an axial raceway 10 corresponding to the axial sliding groove 6. The steel balls 8 are evenly distributed between the axial sliding groove 6 and the axial raceway 10, and the steel balls 8 are connected to each other by the retainer 9. The limiting sleeve 7 is threadedly connected with the shell 1. The steel balls 8 prevent the axial sliding groove 6 from rotating relative to the axial raceway 10, and further prevent the connecting rod 4 from rotating relative to the limiting sleeve 7, by the steel balls 8 between the axial sliding groove 6 and the axial raceway 10. Since the limiting sleeve 7 is fixedly connected with the shell 1, the connecting rod 4 can only move axially, and the frictional resistance of the connecting rod 4 is reduced by the rolling of the steel balls 8 and the connecting rod 4, thereby reducing wear. In consideration of light weight, the shell 1 is generally made of aluminum, but the aluminum material is relatively soft, which leads to poor impact resistance of the shell 1. The limiting sleeve 7 is supported by steel or other impact-resistant metals or alloys, so as to withstand the circumferential impact transmitted to the limiting sleeve 7 through the ball nut screw pair, the connecting rod 2 and the steel balls 8, and ensure the durability of the steer-by-wire assembly. The retainer 9 maintains the relative positions between the steel balls 8, the steel balls 8 and the axial sliding groove 6, and the steel balls 8 and the axial raceway 10, so that the steel balls 8, the axial sliding groove 6 and the axial raceway 10 are uniformly stressed.

[0017] The limiting sleeve 7 at both ends of the retainer 9 is respectively provided with an assembly ring groove 11, and the assembly ring groove 11 is clamped with a circlip 12 for limiting the position of the retainer 9, so as to limit the position of the retainer 9 and further limit the position of the steel balls 8, so that the steel balls 8 are not easy to fall out of the axial sliding groove 6 and the axial raceway 10, and the connection between the steel balls 8, the axial sliding groove 6 and the axial raceway 10 is maintained.

[0018] A check pin 13 is threadedly installed on the shell 1 at one side of the limiting sleeve 7, and the check pin 13 is abuttingly connected with the limiting sleeve 7. The check pin 13 strengthens the connection between the limiting sleeve 7 and the shell 1 by auxiliary threads, prevents the limiting sleeve 7 from loosening, further prevents the limiting sleeve 7 from moving, ensures the limiting of the connecting rod 4 by the limiting sleeve 7, and thus ensures the accurate displacement of the connecting rod 4 under the driving of the steering motor 3.

[0019] The ball nut screw pair includes a lead screw 14 provided at the end of the connecting rod 2, a nut 15 sleeved on the lead screw 14, and balls 16 between the nut 15 and the lead screw 14. The nut 15 is connected with the output shaft of the steering motor 3 through a synchronous belt and a synchronous wheel or through a gear. Preferably, the nut 15 is connected with the output shaft of the steering motor 3 through a synchronous belt and a synchronous wheel.

[0020] The control method of the steer-by-wire assembly includes the following steps: The steering signal of the steering wheel is obtained by the vehicle computer, and is transmitted to the controller 5 of the steer-by-wire assembly. The controller 5 calculates the rotation angle and rotation speed of the steering motor 3 according to the steering signal of the steering wheel, which includes the rotation speed and rotation angle of the steering wheel. The rotation speed of the steering motor 3 is controlled by the rotation speed of the steering motor 3, so as to control the deflection speed of the wheels and the steering speed of the vehicle. The rotation angle of the steering motor 3 is controlled by the rotation angle of the steering wheel, so as to control the deflection angle of the wheels and the steering amplitude of the vehicle. The rotation speed of the steering motor 3 is calculated by the rotation speed of the steering wheel, and the rotation angle of the steering motor 3 is calculated by the rotation angle of the steering wheel.

[0021] The controller 5 controls the rotation of the steering motor 3 according to the calculated rotation angle and rotation speed of the steering motor 3. The steering motor 3 drives the linkage 2 to move the length L1, and then the linkage 2 pulls the wheels to deflect.

[0022] When the linkage 2 moves, the anti-rotation mechanism of the linkage prevents the linkage 2 from rotating. At the same time, the displacement sensor 4 detects the movement distance of the linkage 2. The displacement sensor 4 transmits the displacement distance L2 of the linkage 2 to the vehicle computer and the controller 5. The vehicle computer and the controller 5 compare L2 and L1. When the difference between L1 and L2 is within the set threshold, the steering is completed.

[0023] When the difference between L1 and L2 exceeds the set threshold, the controller 5 repeats the above steps according to the difference between L1 and L2 for feedback adjustment, until the difference between L1 and L2 is within the set threshold, and the steering is completed.

[0024] The specific process of feedback adjustment is as follows: The controller 5 recalculates the rotation angle and rotation speed of the steering motor 3 according to the difference between L1 and L2. The controller 5 controls the rotation of the steering motor 3 according to the calculated rotation angle and rotation speed of the steering motor 3. The steering motor 3 drives the linkage 2 to move, and then the linkage 2 pulls the wheels to deflect. The displacement sensor 4 detects the movement distance of the linkage 2 and feeds back to the vehicle computer and the controller 5. The displacement of the linkage 4 is compared. The cycle is repeated until the difference between L1 and L2 is within the set threshold.

[0025] The steering gear assembly cancels the gear, the connecting piece, the locking piece and the helical teeth on the rack, although the connecting rod anti-rotation mechanism is added, the number of added components is obviously less than the number of canceled components, the production cost of the steering gear assembly can be effectively reduced, and because the number of components is reduced, the machining and assembly links of components in the production process of the steering gear assembly can be effectively reduced, the production efficiency of the steering gear assembly is improved, and the production cost is further reduced. At the same time, because the gear, the connecting piece and the locking piece are canceled, the gear, the connecting piece and the locking piece can be canceled to occupy the engine compartment, the steering gear assembly can reduce the occupation of the engine compartment space, so that the steering gear assembly can be more conveniently arranged. The problem of high production cost of the existing steer-by-wire steering gear is solved.

Claims

1. A steer-by-wire assembly, comprising a housing (1), a connecting rod (2), a ball screw and nut assembly, a steering motor (3), a connecting rod anti-rotation mechanism, and a connecting rod displacement sensor (4), wherein the connecting rod (2) is inserted into the housing (1), and a ball screw and nut assembly for driving the connecting rod (2) is provided at one end of the connecting rod (2), and a steering motor (3) is provided on the housing (1) outside the ball screw and nut assembly, and a controller (5) is provided on the steering motor (3); characterized in that: Axial grooves (6) are evenly distributed around the circumference of the other end of the connecting rod (2). A connecting rod anti-rotation mechanism is provided between the axial grooves (6) and the housing (1). A connecting rod displacement sensor (4) is provided on the housing (1) between the connecting rod anti-rotation mechanism and the ball nut screw pair. The connecting rod displacement sensor (4) is electrically connected to the controller (5).

2. The steer-by-wire assembly according to claim 1, characterized in that: The connecting rod anti-rotation mechanism consists of a limiting sleeve (7), steel balls (8) and a retainer (9). An axial raceway (10) is provided on the inner wall of the limiting sleeve (7) corresponding to the axial slide groove (6). Steel balls (8) are evenly distributed between the axial slide groove (6) and the axial raceway (10). The steel balls (8) are connected to each other through the retainer (9). The limiting sleeve (7) is threadedly connected to the housing (1).

3. A steer-by-wire assembly according to claim 2, characterized in that: The retainer (9) has assembly ring grooves (11) on the limiting sleeves (7) at both ends, and snap rings (12) that limit the position of the retainer (9) are engaged in the assembly ring grooves (11).

4. A steer-by-wire assembly according to claim 2, characterized in that: An anti-loosening pin (13) is threaded on the housing (1) on one side of the limiting sleeve (7), and the anti-loosening pin (13) abuts against the limiting sleeve (7).

5. A steer-by-wire assembly according to claim 1, characterized in that: The ball screw and nut assembly includes a screw (14) at the end of the connecting rod (2), a nut (15) fitted on the screw (14), and balls (16) between the nut (15) and the screw (14). The nut (15) is connected to the output shaft of the steering motor (3) via a timing belt and timing pulley or via gears.

6. A control method for a steer-by-wire assembly, characterized in that: Includes the following steps: 1) The vehicle computer obtains the steering signal from the steering wheel and transmits it to the controller (5) of the steer-by-wire assembly. The controller (5) calculates the rotation angle and rotation speed of the steering motor (3) based on the steering signal from the steering wheel. 2) The controller (5) controls the rotation of the steering motor (3) according to the calculated rotation angle and rotation speed. The steering motor (3) drives the connecting rod (2) to move by the length L1 through the ball nut screw pair, and then pulls the wheel to deflect through the moving connecting rod (2). 3) When the link (2) moves, the movement distance of the link (2) is detected by the link displacement sensor (4); the link displacement sensor (4) uploads the displacement distance L2 of the link (2) to the vehicle computer and controller (5). The vehicle computer and controller (5) compare L2 and L1. When the difference between L1 and L2 is within the set threshold, the steering is completed. 4) When the difference between L1 and L2 exceeds the set threshold, the controller (5) repeats steps 1)-3) to make feedback adjustments based on the difference between L1 and L2 until the difference between L1 and L2 is within the set threshold, and the turn is completed.

7. The control method for a steer-by-wire assembly according to claim 6, characterized in that: When the connecting rod (2) moves, the connecting rod (2) is prevented from rotating by the connecting rod anti-rotation mechanism.

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