Mechanical steering gear assembly with variable spring force and elastic force adjusting method

Abstract

The invention relates to a supporting structure of a variable spring force mechanical steering gear, and belongs to the technical field of automobile steering gears. The assembly comprises a shell, a rack, an input shaft, a supporting seat, an adjusting screw plug and a spring, a center adjusting screw rod is installed on the adjusting screw plug in a threaded mode, and the center adjusting screw rod is connected with the spring in an abutting mode. According to the assembly, the elastic force of the spring can be continuously and accurately adjusted through the center adjusting screw, then the restraining force is accurately adjusted, the abnormal sound of the assembly in the vehicle running process is effectively eliminated through the accurate adjustment of the restraining force, and therefore the comfort degree in the driving process can be effectively improved; the steering gear solves the problems that when an adjusting screw plug directly extrudes a supporting seat, abnormal sound is inevitably generated, and the driving experience is affected.

Description

TECHNICAL FIELD

[0001] The application relates to a support structure of a variable spring force mechanical steering gear and belongs to the technical field of automobile steering gears. BACKGROUND

[0002] The existing steering gear assembly comprises a shell, a rack, an input shaft, a support seat and an adjusting screw plug, the rack is inserted into the shell, the input shaft is movably installed on one side of the shell through a bearing, and the bottom end of the input shaft is engaged with the rack; the support seat is inserted into the shell on the other side of the rack, and the support seat is connected with the rack in abutment; the adjusting screw plug is screwed on the outer side of the shell of the support seat, and the spring is arranged between the adjusting screw plug and the support seat.

[0003] During the driving of the vehicle, the feedback force given by the road is transmitted to the input shaft through the wheel and the rack in sequence. Due to the helix angle of the input shaft gear, the rack will have a tendency to move away from the gear shaft under the action of the input shaft, and a part of the force will be decomposed to the support seat, so that the support seat is subjected to the radial force along the transverse hole of the shell, and the support seat is reciprocally moved radially at the transverse hole of the shell. The function of the spring between the adjusting screw plug and the support seat is mainly to inhibit the reciprocating movement of the support seat after being subjected to the force. When the vehicle is delivered, the gear and the rack are normally engaged during the driving of the vehicle, and the spring force of the spring is sufficient to inhibit the radial force of the support seat, but as the steering gear assembly works for a long time, wear will occur between the input shaft and the rack. As time goes by, as the gap between the input shaft and the rack increases, the rack is prone to collide with the input shaft, thereby causing abnormal noise and affecting the driving experience.

[0004] After the gap between the rack and the input shaft increases, the adjusting screw plug needs to be screwed to increase the spring force of the spring, and then the inhibiting force of the support seat on the rack is increased, so as to avoid the collision between the rack and the input shaft by increasing the inhibiting force, and thereby the abnormal noise is weakened or eliminated. Since the spring is fixed between the support seat and the adjusting screw plug, the stiffness of the spring is fixed, and the spring force can only be increased by increasing the compression amount of the spring. When the adjusting screw plug is screwed, the gap between the adjusting screw plug and the support seat gradually decreases, and when the adjusting screw plug directly presses the support seat, the spring cannot be further compressed, and the inhibiting force cannot be accurately adjusted. After the spring cannot be further compressed, the rack and the input shaft inevitably collide and produce abnormal noise.

[0005] Therefore, it is necessary to design a mechanical steering gear assembly with variable spring force and a spring force adjusting method to solve the above problems. SUMMARY

[0006] The application aims to provide a mechanical steering gear assembly with variable spring force and a spring force adjusting method, which can effectively adjust the spring force, eliminate abnormal noise and ensure the inhibiting force on the rack.

[0007] The technical scheme of the present application is: A variable spring force mechanical steering gear assembly, comprising a housing, a rack, an input shaft, a support seat, an adjusting screw plug and a spring, characterized in that: a central adjusting screw is threadedly installed on the adjusting screw plug, and the central adjusting screw is in abutting connection with the spring.

[0008] The central adjusting screw is provided with a communication hole.

[0009] A spring force adjusting method for a variable spring force mechanical steering gear assembly, characterized in that it comprises the following steps: 1) obtaining the abnormal sound performance of the steering gear under different inhibiting forces and different rack and input shaft clearances through experiments, and forming a spring force adjusting table; 2) after the abnormal sound of the steering gear appears, the adjusting screw plug of the variable spring force mechanical steering gear assembly is turned clockwise (turning 45° can compensate 0.15 mm), so that the adjusting screw plug extrudes the support seat; 3) estimating the rack and input shaft clearance of the steering gear according to the driving mileage of the automobile, finding the inhibiting force corresponding to the spring force adjusting table, and calculating the spring compression amount according to the inhibiting force and the spring stiffness; 4) converting the spring compression amount into the rotation angle of the central adjusting screw, rotating the central adjusting screw, compressing the spring through the central adjusting screw, increasing the spring force, and then increasing the inhibiting force of the support seat on the rack, so as to ensure that the rack and the input shaft are not prone to abnormal sound.

[0010] The experimental step in step 1) is: a. Install the steering gear on the circulating test bench, load 50% of the front axle load on the ends of the rack, rotate the input shaft, and make the rack reciprocate for 100,000 times to wear the rack and the input shaft; b. Detect the clearance of the rack and the input shaft after wear and record it; c. Install the worn steering gear on the whole vehicle, drive on the experimental road at a speed of 15 km / h, and detect the abnormal sound of the steering gear during vehicle driving; d. If there is abnormal sound of the steering gear, rotate the adjusting screw plug and the central adjusting screw, gradually increase the spring force, and repeat step c after increasing the spring force; e. Repeat step d several times until the abnormal sound of the steering gear is eliminated, and record the spring force value (i.e. the initial inhibiting force value) when the abnormal sound is eliminated. After the abnormal sound is eliminated, the steering gear is removed from the whole vehicle; f. Repeat steps a-e, and record the meshing clearance value of the rack and the input shaft after wear and the initial inhibiting force value in the case of increasing the wear of the rack and the input shaft. Based on the original initial inhibiting force value, continue to experiment to obtain the inhibiting force value that can stably prevent abnormal sound after increasing the vehicle speed, and form a spring force adjusting table.

[0011] The elastic force adjusting table has a restraint force that increases with the increase of the gap between the rack and the input shaft.

[0012] The calculation formula of the rotation angle of the center adjusting screw is:

[0013] In the formula, θ is the rotation angle of the center adjusting screw; F is the restraint force value in the elastic force adjusting table after the wear of the gap between the rack and the input shaft; L0 is the gap value between the rack and the input shaft when leaving the factory or the gap value between the rack and the input shaft after the last wear; L1 is the gap value between the rack and the input shaft after the wear or the gap value between the rack and the input shaft after the re-wear; F0 is the spring elastic force value when leaving the factory or the restraint force value after the last wear adjustment; k is the spring stiffness; and P is the pitch of the center adjusting screw.

[0014] The beneficial effects of the present application are as follows: The variable spring force mechanical steering gear assembly and the elastic force adjusting method can continuously and accurately adjust the spring elastic force through the center adjusting screw, thereby accurately adjusting the restraint force, effectively eliminating the abnormal sound of the assembly during the driving process of the vehicle, and effectively improving the comfort during the driving process. The problem of unavoidable abnormal sound when the adjusting plug directly presses the support seat in the existing steering gear is solved, and the driving experience is affected. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structural schematic diagram of the present application; Figure 2 is Figure 1 is an enlarged schematic diagram of A in Figure 3 is Figure 1 is a structural schematic diagram of B-B in

[0016] In the figure: 1, housing, 2, rack, 3, input shaft, 4, support seat, 5, adjusting plug, 6, spring, 7, center adjusting screw, 8, communication hole. DETAILED DESCRIPTION

[0017] The mechanical steering gear assembly with variable spring force comprises a housing 1, a rack 2, an input shaft 3, a support seat 4, an adjusting screw plug 5, and a spring 6. A central adjusting screw 7 is threadedly mounted on the adjusting screw plug 5 and abuts against the spring 6. The central adjusting screw 7 abuts against the support seat 4 and the adjusting screw plug 5 to further compress the spring 6 and increase the spring force of the spring 6, thereby increasing the restraining force on the rack 2, so as to prevent the steering gear from wearing and the rack 2 from making noise with the input shaft 3 after the gap between the rack 2 and the input shaft 3 is increased.

[0018] A communication hole 8 is arranged on the central adjusting screw 7 to communicate the support seat 4 with the outside, thereby preventing air resistance when the central adjusting screw 7 and the adjusting screw plug 5 are adjusted and accurately adjusting the central adjusting screw 7 and the adjusting screw plug 5.

[0019] The spring force adjusting method of the mechanical steering gear assembly with variable spring force comprises the following steps. The experiment obtains the noise performance of the steering gear under different restraining forces and different gaps between the rack and the input shaft, and forms a spring force adjustment table. The specific steps of the experiment are as follows. a. The steering gear is installed on a circulating test bench, 50% of the front axle load is loaded on the ends of the rack, the input shaft is rotated, the rack reciprocates, and the rack and the input shaft are worn for 100,000 cycles; b. The gap of the rack and the input shaft after wearing is detected and recorded; c. The worn steering gear is installed on a vehicle, the vehicle is driven at a speed of 15 km / h on an experimental road, and the noise of the steering gear during driving is detected; d. If the steering gear makes noise, the adjusting screw plug and the central adjusting screw are rotated to gradually increase the spring force, and after the spring force is increased, step c is repeated; e. Step d is repeated multiple times until the noise of the steering gear is eliminated, and the spring force value (i.e. the initial restraining force value) when the noise is eliminated is recorded. After the noise is eliminated, the steering gear is removed from the vehicle; f. Steps a-e are repeated, the meshing gap value of the rack and the input shaft after wearing and the initial restraining force value are recorded under the condition that the rack and the input shaft are worn, the restraining force value that can stably prevent noise after the vehicle speed is increased is obtained based on the original initial restraining force value, and a spring force adjustment table is formed (see the table below).

[0020]

[0021] The noise during the experiment is scored according to the standard in the table below.

[0022]

[0023] The greater the inhibiting force, the tighter the rack and the input shaft engage, and the less likely the abnormal noise. However, the greater the inhibiting force, the greater the force between the rack and the input shaft, and the greater the wear of the rack and the input shaft (see the table below). Thus, the value of the inhibiting force cannot be increased indefinitely, and the value of the inhibiting force is reduced as much as possible while preventing abnormal noise.

[0024]

[0025] After the steering gear produces abnormal noise, the adjusting screw plug of the variable spring force mechanical steering gear assembly is turned clockwise (turning 45° can compensate 0.15 mm), so that the adjusting screw plug presses the support seat. The number of turns of the adjusting screw plug is a fixed value, which is determined according to the model of the steering gear. The larger the steering gear, the more turns of the adjusting screw plug.

[0026] As the mileage of the automobile increases, the number of cycles of the steering gear increases, and the reverse impact of the road on the steering gear increases, so the wear of the steering gear, i.e., the wear of the rack and the input shaft, increases. Thus, the clearance between the rack and the input shaft can be estimated according to the mileage of the automobile. For example, when the automobile travels 50,000 km, the clearance between the rack and the input shaft is 0.12 mm; when the automobile travels 80,000 km, the clearance between the rack and the input shaft is 0.20 mm; and when the automobile travels 100,000 km, the clearance between the rack and the input shaft is 0.22 mm.

[0027] The inhibiting force is found by referring to the spring force adjustment table corresponding to the clearance between the rack and the input shaft, and the spring compression amount is calculated according to the inhibiting force and the spring stiffness.

[0028] The calculation formula of the spring compression amount is: In the formula, △F is the spring force increase amount, and k is the spring stiffness.

[0029] After the rack and the input shaft wear, the spring will relax, and the spring force increase amount is:

[0030] In the formula, F is the inhibiting force value in the spring force adjustment table corresponding to the clearance between the rack and the input shaft after wear, F1 is the spring force value after relaxation, L0 is the clearance value between the rack and the input shaft at the factory or the clearance value between the rack and the input shaft after the last wear, L1 is the clearance value between the rack and the input shaft after wear or the clearance value between the rack and the input shaft after further wear, F0 is the spring force value at the factory or the inhibiting force value after the last wear adjustment, and k is the spring stiffness.

[0031] The spring compression amount is converted into the rotation angle of the center adjusting screw, the center adjusting screw is rotated, the spring is compressed through the center adjusting screw, the spring force is increased, the restraining force of the support seat on the rack is increased, and the abnormal noise between the rack and the input shaft is prevented.

[0032] The restraining force in the spring force adjustment table increases with the increase of the gap between the rack and the input shaft.

[0033] The calculation formula of the rotation angle of the center adjusting screw is:

[0034] In the formula, P is the pitch of the center adjusting screw.

[0035] For example, after the first wear, the spring force F0 at the factory is 500 N, the gap L0 between the rack and the input shaft at the factory is 0.05 mm, the gap L1 between the rack and the input shaft after wear is 0.2 mm, the restraining force F is 750 N, the spring stiffness k is 300 N / mm, and the center rod adjusting pitch P is 1.2 mm. Substituting into the above formula, the center screw rotation angle θ is calculated to be 295 degrees; after the second wear, the restraining force F0 after the last adjustment is 750 N, the gap L0 between the rack and the input shaft after the last adjustment is 0.2 mm, the gap L1 between the rack and the input shaft after the second wear is 0.45 mm, the restraining force F is 1000 N, the spring stiffness k is 300 N / mm, and the center rod adjusting pitch P is 1.2 mm. Substituting into the above formula, the center screw rotation angle θ is calculated to be 325 degrees; and the same is true for the subsequent adjustment.

[0036] The variable spring force mechanical steering gear assembly and the spring force adjustment method can accurately adjust the spring force through the center adjusting screw, and then accurately adjust the restraining force. Through the accurate adjustment of the restraining force, the abnormal noise of the assembly during vehicle driving is effectively eliminated, thereby effectively improving the comfort during driving. The problem of unavoidable abnormal noise when adjusting the screw plug directly pressing the support seat in the existing steering gear is solved.

Claims

1. A method for adjusting the spring force of a variable spring force mechanical steering gear assembly, characterized in that: It includes the following steps: 1) The experiment obtained the abnormal noise performance of the steering gear under different damping forces and different clearances between the rack and the input shaft, and formed a spring force adjustment table; 2) After abnormal noise occurs in the steering gear, turn the adjusting screw of the variable spring force mechanical steering gear assembly clockwise to press the adjusting screw against the support seat; 3) Estimate the clearance between the steering rack and the input shaft based on the vehicle's mileage, find the damping force in the corresponding spring adjustment table, and calculate the increase in spring compression based on the damping force and spring stiffness; 4) Convert the increased compression of the spring into the rotation angle of the center adjusting screw. Rotate the center adjusting screw to compress the spring, increase the spring force, and thus increase the restraining force of the support on the rack, ensuring that there is less abnormal noise between the rack and the input shaft.

2. The spring force adjustment method for a variable spring force mechanical steering gear assembly according to claim 1, characterized in that: The experimental steps in step 1) are as follows: a. Install the steering gear on the cyclic test bench, apply 50% front axle load to both ends of the rack, rotate the input shaft to make the rack reciprocate for 100,000 cycles to wear down the rack and input shaft. b. Inspect and record the clearance between the rack and input shaft after wear; c. Install the worn steering gear on the vehicle and drive it at a speed of 15 km / h on the test road to detect abnormal noise from the steering gear during vehicle operation; d. If there is abnormal noise from the steering gear, rotate the adjusting screw and the center adjusting screw to gradually increase the spring force. After increasing the spring force, repeat step c. e. Repeat step d multiple times until the abnormal noise from the steering gear is eliminated, and record the spring force value when the abnormal noise is eliminated. After the abnormal noise is eliminated, remove the steering gear from the vehicle. f. Repeat step ae. Under the condition of increasing the wear of the rack and input shaft, record the meshing clearance value and the initial damping force value after the wear of the rack and input shaft. On the basis of the original initial damping force value, continue the experiment to obtain the damping force value that can stably prevent abnormal noise even after the vehicle speed increases, and form the spring force adjustment table.

3. The spring force adjustment method for a variable spring force mechanical steering gear assembly according to claim 1, characterized in that: The damping force in the elasticity adjustment table increases as the gap between the rack and the input shaft increases.

4. The spring force adjustment method for a variable spring force mechanical steering gear assembly according to claim 1, characterized in that: The formula for calculating the rotation angle of the center adjusting screw is: ； In the formula, θ is the rotation angle of the central adjusting screw; F is the damping force value in the spring force adjustment table for the clearance between the rack and input shaft after wear; L0 is the clearance value between the rack and input shaft at the factory or after the last wear; L1 is the clearance value between the rack and input shaft after wear or after further wear; F0 is the spring force value at the factory or the damping force value after the last wear adjustment; k is the spring stiffness; P is the pitch of the center adjusting screw.

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