WO2016093733A1

WO2016093733A1 - Two-stage shock absorber

Info

Publication number: WO2016093733A1
Application number: PCT/RU2015/000512
Authority: WO
Inventors: Владимир Викторович РОМАНОВ; Софья Владимировна РОМАНОВА; Елена Анатольевна РОМАНОВА; Валерий Викторович РОМАНОВ; Сергей Викторович БАЗЮК
Original assignee: Владимир Викторович РОМАНОВ; Софья Владимировна РОМАНОВА; Елена Анатольевна РОМАНОВА; Валерий Викторович РОМАНОВ; Сергей Викторович БАЗЮК
Priority date: 2014-12-11
Filing date: 2015-08-14
Publication date: 2016-06-16
Also published as: RU2597061C2; RU2014150237A

Abstract

In order to insulate the body of a vehicle against dynamic loads on the vehicle resulting from motion along an uneven surface, spring-damping systems are used which consist of an elastic member and of a damper installed parallel to same. It should be noted that only the elastic member acts as an insulator. The damper, the aim of which is to dampen auto-oscillation, worsens the insulation characteristics of the spring-damping system because, being installed between an unsprung mass and a sprung mass, the damper transfers vertical momentum from a wheel to the body of the vehicle, and must thus dampen oscillations which it produces itself. In the claimed two-stage shock absorber (fig. 3), consisting of two spring-damping systems (7, 8) having unidirectional dampers, the damper of one stage (1) inhibits only compression, while the damper of the other stage (2) inhibits only elongation. In such a device, the transfer of vertical momentum from a wheel (6) to the body of a vehicle (5) via dampers is completely eliminated. Auto-oscillation is also dampened fairly effectively.

Description

TWO-STAGE SHOCK ABSORBER

Technical field

The invention relates to the field of transport engineering, namely, suspension devices of vehicles (hereinafter TS), can also be used as vibration isolation of machines and seismic isolation of buildings and structures.

State of the art

The vehicle suspension system is mainly provided for isolating the main structure, i.e. the vehicle body from road roughness. However, the suspension also plays an important role in reducing the amount of energy expended when the vehicle encounters bumps in its path. The vehicle rests on the road with a wheel (ski, tracked roller), which is connected to the vehicle body by a corresponding swivel joint. Different swivel joints provide a different trajectory of the free movement of the wheel relative to the vehicle body, but this trajectory is usually close to the vertical axis. To keep the vehicle body in a normal position relative to the wheel between the wheel axis and the vehicle body, a spring is installed, which is an energy storage device, that is, it is compressed (bent, stretched, twisted) under the influence of the vehicle body weight to the equilibrium position.

The wheels, hubs, wheel axle, brake device are generally called the unsprung mass, and the vehicle body, including the driver’s cab and passenger compartment, is called the sprung mass. The device of the most widely used types of car suspensions is described in detail in the book “Car Chassis” by Raimpel J. Mechanical Engineering, 1983.

Springs are known for sheet, screw (spiral), torsion, pneumatic, hydropneumatic, electromagnetic, using the elasticity of materials, working on compression, tension, bending, twisting.

Discomfort from road bumps means overloads in the form of jerks and failures that passengers and the driver experience when the vehicle encounters road bumps in its path. The magnitude of these overloads is determined by the magnitude of the acceleration of the sprung mass along the vertical axis. This acceleration is determined by the formula:

A - acceleration of the sprung mass along the vertical axis;

Fr - spring reaction force;

Fv is the part of the vehicle body weight force attributable to this spring;

m is the part of the sprung mass attributable to this spring;

G is the acceleration of gravity.

At the equilibrium point, the vehicle body weight force and the spring reaction force are equal, therefore, the acceleration along the vertical axis is also zero. When the wheel rises above a point when hitting an obstacle equilibrium, the spring is compressed, the reaction force increases and becomes greater than the weight force attributable to this spring. The difference between these forces is positive and the acceleration is directed upwards. When the wheel falls below the equilibrium point, the spring reaction force decreases, and the Fr – Fv difference becomes negative. The acceleration in this case is directed downward. The change in the reaction force of the spring when the wheel moves along the vertical axis is the smaller, the better the compression characteristic of the spring. That spring is an effective filter from any perturbations of the wheel along the vertical axis. But the system - the vehicle body, suspended on springs (elastic elements without permanent deformation) is not stable, since it is an oscillatory system. When moving, such a system sways and easily enters into resonance. Therefore, various methods are used to calm the vibrations. The most common method is the use of a damper, which, when compressing and uncleaning the spring, absorbs the energy of the vertical impulse of the wheel and stops unwanted vibrations of the vehicle body.

A node is a spring, the elastic deformation of which is damped by a damping device, called springs, a no-damper system. In most cases, the damping device is installed parallel to the spring, except for the hydropneumatic suspension. There, the damper, which is a valve with a calibrated bore, is installed in series with a hydropneumatic spring. Dampers are known hydraulic, gas, friction, electromagnetic, dynamic, working on internal friction. Dampers in their action are divided into two groups - these are single-acting dampers and double-acting dampers. In a single-acting damper, when its elements move relative to each other or the working fluid moves relative to its body in one direction, significant resistance is created, and in the other, insignificant resistance. The double-acting damper provides resistance in both forward and reverse travel. It should be noted that it is impossible to completely get rid of resistance with the free-wheeling of a one-way damper without additional efforts from the outside, so there is no exact border between the dampers of unilateral and bilateral action.

A vehicle suspension having one spring-damper system with one single-acting damper with a single-acting damper, which slows down the suspension stroke, works as follows: When hitting a threshold-like protrusion (Fig. 1), the wheel moves around the vertical axis around the obstacle . The spring is compressed, absorbing the main part of the vertical impulse of the wheel. The vehicle body, having a large mass, moves slightly along the vertical axis, taking an insignificant part of the impulse of the wheel. The damper in this phase does not interfere with spring compression and does not transmit a significant impulse to the vehicle body. Having risen on a flat surface, the spring tends to expand to the equilibrium position, but the damper, resisting stretching, inhibits the expansion, absorbing the energy of the compressed spring, and stops the vehicle body moving up close to the equilibrium point. Such an obstacle (figure 1) suspension with single-acting damper overcomes well. When hitting an unevenness, protruding above the road surface (bump) (figure 2), the spring is compressed on the rise, and at the exit is unclenched. The damper in the phase of exit from the roughness actively resists the release, thereby counteracting the spring reaction force, which in turn holds the weight of the vehicle body. The force with which the damper holds the spring, in direct proportion to the vertical component of the wheel speed, that is, the speed of the spring unclenching and in its maximum value reaches the spring reaction force. The acceleration of the vehicle body along the vertical axis in this phase is determined by the formula:

Fr-fd-fv

A = x G, where

m

Fd is the resistance force of the damper during expansion.

During the time until the wheel reaches the lowest point in its trajectory, the vehicle body receives acceleration down the vertical axis, which can reach the value of the gravitational acceleration. In this phase, passengers and the driver experience congestion failures. In addition, the pressure of the wheel on the road surface decreases, up to the separation of the wheel from the road surface, which inevitably leads to poor handling and even loss of control for some time. When the wheel reaches the lowest point in its trajectory, the impulse that the vehicle body received during the exit from the bumps absorbs the spring. The damper in this phase does not interfere with compression and does not create braking forces. In this phase, the acceleration of the vehicle body, directed upwards, is determined by the formula:

Fr— Fv

A = x G

m

The difference between the reaction force and the weight force is small and appears only when the spring is compressed beyond the equilibrium point and reaches its maximum value with maximum spring compression. In this phase, passengers and the driver do not experience noticeable overloads, but there is a risk of breakdown of the suspension to the extreme position. If the bumps on the road are one after another, then the breakdown comes even faster. This phenomenon is the main disadvantage of spring-damper systems using single-acting dampers, therefore they are rarely used: on multi-axis vehicles, or when multi-leaf springs with a tightly compressed package are used, since such springs already have a double-sided damping effect due to friction between the sheets.

In modern vehicles, this problem is solved by the use of double-acting dampers. Typically, these dampers have different compressive and tensile strengths. Compression less resistance, greater tensile. In view of this, the vertical impulse of the wheel is transmitted to the vehicle body through the damper both during forward and reverse travel.

A double-acting damper installed parallel to the spring to absorb unwanted vibrations increases the stiffness of the suspension. Suspension using double-acting dampers has a number of significant disadvantages:

1. Such a suspension can only cope with small and smooth bumps;

2. The use of soft springs with a gentle compression characteristic does not relieve jerks and failures, since they are transmitted from the wheel to the vehicle body for the most part through a damper;

3. The softer the spring, that is, its compression characteristic, the lower the resonant frequency of the oscillatory system — the vehicle body suspended on the spring, therefore, the lower the instantaneous compression and extension speed of the damper, which forces the use of stiffer dampers.

In fact, the damper has to calm the vibrations that he himself excites.

To reduce the harmful effects of dampers in some suspension structures, various electronic-mechanical systems are used, which use information obtained from the vertical acceleration sensors of unsprung masses and the vehicle body, tire deformation sensors, road surface locators and introduce corrective forces into the suspension when help of electromechanical and electro-hydraulic systems. A similar system is described in patent RU 2395407. These systems are very complex and expensive and are used only in the most expensive models.

Disclosure of invention

A two-stage shock absorber installed between the sprung (5) and unsprung mass (6) consists of two spring-damper systems (7.8) with single-acting dampers, moreover, in one spring-damper system, a direct-acting damper (1), in the other reverse (2), spring-damper systems can be installed sequentially, one above the other (FIG. 3) or in parallel (FIG. 4, FIG. 5). In this case, the use of a balancing lever (9) is necessary. In the hydropneumatic suspension of a wheel or group of wheels (Fig. B), two hydropneumatic spring-damper systems with single-acting dampers are installed. In one damper direct action, in the other reverse.

A two-stage shock absorber operates as follows:

When the vehicle meets irregularities in its path, the wheel, repeating the relief of the road surface, moves along the vertical axis. When moving upward, the spring-damper system (7) with a direct-acting damper (Fig. 3, Fig. 4, Fig. 5, Fig. B) does not compress, and the spring-damper system (8) with a reverse damper is compressed, since its damper (2) does not interfere with compression and does not transmit the momentum of the wheel to the sprung mass (5). When the wheel moves down the vertical axis, the reverse damper (2) slows down the compression of the corresponding spring-damper system (8), but the spring-damper system (7) with the direct damper prevents the sprung mass from falling through, since the direct damper (1) does not resist unclenching. The acceleration of the sprung mass along the vertical axis when the wheel moves up is determined by the formula:

, Fra-Fv „

A = x G, where

m

Fra - reaction force of the spring (4) of the spring damper system (8) with a reverse damper (2). The acceleration of the sprung mass along the vertical axis when the wheel moves down is determined by the formula:

. Frb-fv_

A = x G, where

m

Frb is the reaction force of the spring (3) of the spring-damper system (7) with a direct-acting damper (1). Thus, the weight of the vehicle body is held by the reaction force of the springs (3.4), and the impact on the wheel

the vertical axis, as well as a sharp failure, the spring can not transmit the chassis of the vehicle. The force with which the damper inhibits elastic deformation does not exceed the difference in the reaction forces of the springs of one two-stage shock-absorbing device. However, the self-oscillations in such a damper device are extinguished quite effectively.

A two-stage shock absorber has the following advantages:

1. The reaction force of a two-stage shock-absorbing device during suspension operation varies slightly, which reduces the acceleration of the sprung mass along the vertical axis, and hence overloads that cause discomfort, to insignificant values.

2. A suspension with a two-stage shock-absorbing device presses the wheel to the road surface while driving continuously with little changing effort, even on rough roads, which is necessary for good handling.

3. The absence of jumps in the reaction force in a two-stage shock-absorbing device allows you to avoid damage to tires during collisions with bumps.

4. The reduction of the forces arising in the dampers of the two-stage shock-absorbing device allows to reduce the amount of energy expended when the vehicle overcomes irregularities in its path.

5. The reduction of the forces arising in the dampers of a two-stage shock-absorbing device allows them to be made more compact and cheaper.

Brief Description of the Drawings

Figure 1 shows the suspension with a single-acting damper of a vehicle overcoming a threshold-like obstacle. Between the sprung mass (5) and the unsprung mass (6), a spring (4) is installed and a reverse damper (2) parallel to it.

Figure 2 shows the suspension with a single-acting damper of a vehicle overcoming an obstacle of the form of a bump, that is, protruding above the surface of the road. Fig. 3 shows a diagram of a two-stage shock-absorbing device with spring-damper systems (7.8) connected in series, with the damper (1) of the spring-damper system (7) of direct action, and the damper (2) of the spring-damper system (8) of the reverse actions. Figure 4 shows a diagram of a two-stage shock-absorbing device with parallel connected spring-damper systems. In a parallel circuit, a balancing lever (9) is required.

Figure 5 shows a diagram of a two-stage shock absorbing device for tandem wheels. In Fig. B shows a diagram of a two-stage shock absorbing device for hydropneumatic suspension. In such a suspension, the spring-damper systems are connected in parallel with each other, however, the damper and the elastic element are connected in series.

Figure 7 shows one of the options for a two-stage shock-absorbing device, combined in one suspension strut.

On Fig depicts one of the options for a two-stage shock absorber arranged in a rack for use in the suspension "MacPherson".

Figure 9 shows one of the options for a two-stage shock absorbing device for tandem wheels using a leaf spring

Figure 10 shows one of the options for a two-stage shock absorbing device for suspension with a longitudinal leaf spring.

Figure 11 shows a variant of a two-stage shock-absorbing device in which a spring-damper system is added to the MacPherson strut with a reverse damper (2), supported by a lever (10) on top of the pillar support bearing (11). The elastic element (13) is torsion. Damper (12) reverse action, but inhibits elastic deformation corresponding to an increase in load.

The implementation of the invention

The use of a two-stage shock-absorbing device does not require major changes in the suspension design of the vehicle. For many models of modern cars, the suspension can be literally refitted, that is, the standard elastic element and damper are replaced by a two-stage shock absorber arranged in one rack (Fig. 7). In the MacPherson strut, the strut experiences a bending force, the magnitude of which is greater than the bottom of the strut, where the wheel axle is attached to it, so it’s best to place the retractable strut elements in its upper part. One of the options for such a layout is shown in Fig. 8.

It should be noted that the parameters of the elastic elements in the two-stage shock-absorbing device (Fig. 7, Fig. 8) are selected so that in the equilibrium position the elastic element (3), working together with the direct-acting damper (1), is in the most compressed position or close to the maximum compressed position, and the elastic element (4), working together with the reverse action damper (2), it is in the maximum open position or close to the maximum open position. This is necessary because in the operation of a two-stage shock-absorbing device, a spring-damper system with a direct-acting damper never compresses closer to the equilibrium point, and a spring-damper system with a direct-action damper never expands beyond the equilibrium point.

In a hydropneumatic suspension, conversion to a two-stage scheme is carried out by replacing a standard elastic element with two elastic elements with damping devices corresponding to a two-stage scheme.

Claims

Claim

1. A two-stage shock-absorbing device consisting of two spring-damper systems interconnected in such a way that when the sprung mass remains unchanged relative to the unsprung mass, forced elastic deformation of one spring-damper system, corresponding to an increase in load, causes elastic deformation of another spring-damper a system corresponding to a reduction in load, characterized in that in one spring-damper system a single-acting damper is installed, which Ormoz elastic deformation corresponding to the increase of the load, while the other spring-damper system has a damper single direction, which inhibits the elastic deformation corresponding to the stress reduction.

2. The two-stage shock-absorbing device according to claim 1, characterized in that a damper is installed in one spring-damper system, which mainly slows down the elastic deformation corresponding to an increase in load and with much lower efficiency slows down an elastic deformation corresponding to a decrease in load, and in the other spring - a damper is installed in the damper system, which mainly slows down the elastic

deformation corresponding to a decrease in load and with much lower efficiency inhibits elastic deformation corresponding to an increase in load.

3. The two-stage shock-absorbing device according to claim 1, characterized in that a damper is installed in one spring-damper system, which mainly slows down the elastic deformation corresponding to an increase in load and slows down the elastic deformation with a much lower efficiency, corresponding to a decrease in load, and in the other spring - a single-acting damper is installed in the damper system, which inhibits the elastic deformation corresponding to the reduction of the load.

4. The two-stage shock-absorbing device according to claim 1, characterized in that in one spring-damper system a single-acting damper is installed that inhibits the elastic deformation corresponding to an increase in load, and in another spring-damper system there is a damper which mainly inhibits the elastic deformation, corresponding to a decrease in load and with much lower efficiency inhibits elastic deformation corresponding to an increase in load.