RU2238534C2 - Method of testing vehicles - Google Patents

Abstract

FIELD: testing of vehicles.

SUBSTANCE: method comprises standard procedure of measuring the divergence of the control wheels of a vehicle without the preliminary elimination of gaps in rotation axles, pivots of the tierod, levers, and bearings of the front wheels, by applying artificial forces to the wheel control equivalent to the actual ones in magnitude and direction.

EFFECT: enhanced reliability.

2 cl, 4 dwg

Description

The invention relates to methods for technical diagnostics of steering vehicles and may find application in their operation.

The current method for diagnosing the steering consists mainly in determining the angular value of the free wheeling (total play) of the steering wheel, which is used to judge the admissibility of further work or the need for a laborious operation to identify nodes that require repair. At the same time, the convergence parameter remains unexplored, which has a significant effect on the stabilization of the front wheels, road stability and vehicle handling (Rodichev V.A. Passenger car. M: Profizdat, 2001, p. 63). If the convergence parameter deviates from the optimum value, its effect on accelerated wear of steering parts is enhanced, in which a vicious circle of a mutually accelerating process is formed - wear and convergence changes, and with it deterioration of stability and controllability. And if, with an optimal positive value recommended by the manufacturer, caused by their collapse and convergence, they are counter-compensated and mutually compensated, then with a negative adjustment or incorrect adjustment, these forces are directed according to and summed, with each of the front wheels experiencing force lateral displacement. The resultant of these forces when driving with reliable grip is close to zero and causes only increased wear of the tread of the tires, but when contact is lost (slush, ice, etc.), especially with one wheel, this balance of forces is violated, leading to poor stability and manageability, and in especially adverse cases, to their loss. These negative phenomena can be prevented by maintaining convergence at the optimal level by timely correction or expensive repairs with subsequent adjustment.

Existing diagnostic methods exclude the possibility of diagnosing and correcting convergence, as require preliminary elimination of backlash in the axes of rotation, hinges of steering rods and levers (Yakovenko EG. Stationary stand “Optoflex”, ed. “Organization of maintenance and repair of automobiles“ Zhiguli ”. M .: Transport, 1976, p. 88). Similar requirements are set out in clause 6.1.4. instructions for using the PSK-LG portable device for measuring the convergence of steered wheels of cars and trucks (TU 2. 034.00221071.060-93), and consisting of a sliding metal ruler with a metric scale. The value of convergence with its help is defined as the difference in the length of the ruler at the beginning and end of the measurement. The PSK-LG device is adopted as a prototype of the proposed method for controlling the convergence and total play of the steering trapezoid and the nodes of the rotary racks, which functionally repeats the technology of using the PSK-LG device with the exception of the preliminary elimination of backlash forcedly selected during the measurement by artificial forces equivalent in magnitude and direction to the forces resistance to real movement. Moreover, in one cycle with the toe control, the total backlash of the conjugated joints of the steering trapezoid (hinges of the side rods) and the nodes of the rotary racks (bearings of the front wheels, levers and ball bearings) is additionally determined. For the mentioned artificial efforts, their minimum value is critical, which should be sufficient for a reliable selection of gaps (equivalent to moving on a smooth road with a moderate speed). When it is significantly exceeded, the elastic deformation of the loaded nodes caused by it is small and does not introduce a noticeable error in the measurements. These efforts can be both continuous and concentrated.

The functioning of the method of controlling the toe and the total play of the steering trapezoid and the nodes of the rotary racks is as follows:

the vehicle is installed in accordance with the typical conditions of such tests on a flat horizontal platform after driving forward and braking.

On the front steered wheels, a sliding measuring rod is installed with a reversing linear displacement sensor controlling the change in its length at points located at the same distance from the axes of rotation of the wheels and at the same height from the road surface. In this case, the most rational installation of the rod on the radius of the average trapezoid traction, because the length of the rod at the lower point of its trajectory in the measurement cycles is minimal due to the collapse of the front wheels and the expansion of the tires under the influence of the weight of the vehicle, therefore, the directions of sampling of the sensor’s own play at the moments of registration of the measured values and during its installation (with the rod) coincide, and this automatically excludes the influence of play on the measurement error, which is not always true when installing the rod on the wheel rims.

Further, the distance between the points of installation of the rod is fixed and conditionally taken equal to zero, as in the measurements with the PSK-LG device. In order to obtain the value of the convergence taking into account the existing gaps in the elements of the steering trapezoid and the nodes of the rotary racks and determine their total value, the vehicle is moved to the positions where these parameters are recorded, with artificial resistance to the movement of the front wheels, the force of which is transmitted to the mating parts steering trapezoid and nodes of the rotary racks, while maintaining and maintaining the direction of selection of backlash of the initial position. The vehicle is rolled forward to a distance at which the measuring rod with the sensor reaches the same height as in the initial position and measure the change in the distance between the control points, taking into account its sign, which is used to judge the convergence. Then the vehicle is returned to its original position, also with resistance to movement, in which the backlash of the conjugate joints of the steering trapezoid and the nodes of the rotary struts are displaced in the opposite direction, and again measure the change in the distance between the control points (from the original, taken equal to zero), which is judged the value of the total play of the steering trapezoid and the nodes of the rotary racks. The obtained numerical values of the convergence and total play parameters are reduced to the line (radius) of the installation of the measuring rod.

To perform a comprehensive diagnosis of the steering according to paragraph 1 of the “Method” formula, the total backlash of the hinges of the left and right steering rods, in total, making up the linear play of the steering trapezoid, as well as the corner play of the steering along the left and right front wheels with their linear dimensions, are additionally measured to the average thrust of the steering trapeze. The obtained numerical values are entered into the system of three algebraic equations, the solution of which allows us to determine the total backlash reduced to the average thrust:

1) steering gear with steering link trapezoid

ΔР = (Σ Rights + Σ Leo-Σ Tp) / 2,

where ΣPrav - free wheel steering on the right wheel, given in linear dimensions to the average thrust of the steering trapezoid;

ΣLev - the same on the left wheel;

ΣTp is the total play of the steering trapezoid with the nodes of the left and right swivel racks, measured in one cycle with the convergence control (naturally, bringing it to the line of the average trapezoid traction if the measuring rod is not installed on its radius).

2) the node of the left rotary rack

ΔLst = ΔР-Σ Rights + ΣTp-ΔShlev,

where ΔShlev is the total play of two hinges of the left tie rod of the steering drive.

3) knot of the right rotary rack

ΔPr = ΔP-Σ Leo + Σ Tr-ΔShpr,

where Δ Shpr is the total play of two hinges of the steering rod’s right-hand rod.

Figure 2 shows a simplified calculated kinematic steering scheme, where:

9 - steering gear

10 - the leading hinge of the steering trapezoid,

11 - node of the left rotary rack with levers, ball bearings and bearings 12 of the left wheel,

13 - the same right swivel rack with bearings 14 of the right wheel,

15 - left tie rod with two joints,

16 - the same, right thrust.

The above formulas are the result of a mathematical transformation of three algebraic dependencies (Σ Tr, Σ Lev, Σ Rights), which describe the natural connection of the nodes of the kinematic steering scheme.

From figure 2

The technical result of the method consists in obtaining a volume of diagnostic information sufficient to assess the condition of not only the steering system as a whole, but also the most difficult and time-consuming to diagnose nodes of the left and right steering racks and the steering mechanism when using a comparatively small amount of instrumental measurements, which simplifies the diagnostic process while increasing its information content. This eliminates the error that is possible with other control methods, when the steering wheel clearance is measured only on one front wheel from the side of the steering mechanism, while the same play on the other front wheel can be significantly larger, for example, in right-hand traffic, when due to the transverse slope of the roadway, the nodes of the right swing pillars are more loaded and wear out more intensively. According to the proposed method, these measurements are required on both front wheels. Diagnosis and maintenance of optimal toe-in of the steered wheels with parallel control of the steering wheel angle increases the level of safety and controllability of the vehicle while reducing the abrasive wear of the tread of rear-wheel drive cars. For front-wheel drive vehicles in acceleration and braking modes, the resulting forces acting on the front wheels (and accordingly their moments relative to the axes of the rotary racks) reverse direction, shifting the wheels in the entire range of the total clearance of the steering trapezoid and the nodes of the rotary racks. Therefore, the optimum adjustment of the convergence in this case is effective only in a narrow range of these backlashes, and control of their magnitude is more relevant than for rear-wheel drive.

The list of graphic materials: figure 1 shows a variant of the device for implementing the method of measuring the convergence and total play ΣТр, consisting of:

- from power spring-loaded stops 1, which serve to create concentrated artificial forces acting on the front wheels and issue an electrical signal for registering parameters when an adjustable setting of these forces is achieved, combined with raising the reference position of the measuring rod 5 to a reference height by moving these stops;

- measuring sliding rod 5, technologically repeating the design of the prototype PSK-LG with replacing its metric scale with a reversing sensor 4 with its mount;

- control unit 3, which serves to visually control the change in the length of the rod 5 from its original (conditionally zero) value and its fixation. For this, simple schemes for reversing the counting of discrete information in the form of a unitary code are suitable, for example, a scheme is known (see Bystrov Yu.A. et al. One hundred schemes with indicators. M: Radio and Communication, 1990, p. 63 Fig. 3.14). For monitoring linear displacements, sensors with a discrete representation of information are applicable, for example, “A device for measuring linear and angular displacements” VA Grishin, SV Nicheporuk, application per. No. 93002768/28 of 01/14/1993 or developed by the authors “Device for measuring linear and angular displacements in the diagnosis of vehicles” (patent No. 220068 of 06.06. 2002). Figure 2 presents a simplified calculated kinematic scheme of the steering. Figure 3 shows in more detail the measuring rod 5 with the mounting unit of the sensor 4, and figure 4 - power spring stop 1, consisting of a swivel joint “a”, a removable spring strut “b” with a microswitch moving along the arrow “d” b ”for setting the value of the actuating force F ₂ . In this case, the force F ₁ from the vehicle’s own force acting on the sole of the power stop prevents its displacement under the action of the force F ₂ . When creating continuous artificial forces, for example, by moving the front wheels on an elastic rubber tape 30-40 mm thick or braking with the on-board brake system, the indicated convergence and total play ΣTp measurements are possible using the prototype PSK-LG or similar devices.

Functional testing of the “Method” was carried out on Moskvich M412 and VAZ-2109 passenger cars using an experimental combined device that combines methods of convergence measurement and total play Σ Tr with determination of steering angle play, giving stable and reliable diagnostic results, confirmed by long-term practice.

Claims (2)

1. The method of technical diagnostics of the steering control of a vehicle, which consists in measuring linear backlash of the right and left steering rods of the steering drive, measuring the free wheeling of the steering wheel along the left and right steered wheels, leading the measured free wheeling of the steering wheel in linear dimensions to medium thrust steering trapezoid ΣLev and ΣRights, characterized in that they measure the amount of convergence and the total play of the steering trapezoid and the nodes of the rotary racks ΣТр, divide the kinematic chain, creating steering backlash Aviation, into four groups: backlash of the steering trapezoid ΔТр, backlash of the steering mechanism with a leading hinge of the steering trapezoid ΔР, backlash of the knot of the right rotary pillar ΔPst, backlash of the knot of the left rotary pillar ΔLst and determine them by the formulas: ΔР = (ΣLev + ΣRights - ΣТр) / 2 ΔLst = ΔР-ΣRight + ΣТр - Δ Shlev ΔPst = ΔР - ΣLev + ΣТр - Δ Shpv, where ΔShlev is the total play of two hinges of the left tie rod of the steering drive, ΔShprav - the total backlash of the two hinges of the right-hand drive rod, which is measured instrumentally. 2. A method of measuring the convergence of the steered wheels of the vehicle and the total play of the steering trapezoid and the nodes of the rotary racks, which consists in the fact that on the steered wheels a measuring sliding rod with a reversing linear displacement sensor is installed at points that are at the same distance from the axes of rotation of the wheels and one height from the road surface, the distance between which is fixed and conditionally taken as zero, characterized in that they create conditions under which the steering elements forces are acting that are equivalent in magnitude and direction to the real forces arising from the movement of the vehicle, which is rolled to a distance at which the measuring sliding rod reaches the same height as in the initial position, measure the change in the distance between the control points, which judge about the amount of convergence of the steered wheels, taking into account its sign, then return the vehicle to its original position, at which the change in the distance between the control points is again measured the second one is judged on the value of the total backlash of the steering trapezoid and the nodes of the rotary racks ΣТр.

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