RU2801906C1 - Dual-mode suspension system of a vehicle with adjustable ground clearance - Google Patents

Abstract

FIELD: springs.

SUBSTANCE: invention relates to a spring structure comprising a cylindrical damper (5), a main coil spring (9) with a first predetermined spring stiffness K1 and an auxiliary coil spring (11) with a second predetermined spring stiffness K2, wherein the coil springs are sequentially arranged around the cylindrical damper (5) creating an overall stiffness KT of the springs, an actuator (20) configured to compress and decompress the coil springs (9, 11), a stop (12) configured to disable the auxiliary coil spring (11) at the stop location, so that when the system is in the first comfort mode, the total spring rate of the suspension is given by the sequence equation KT = K1.

EFFECT: selectively switching both low stiffness and high stiffness.

11 cl, 21 dwg

Description

Technical field

The invention relates to a suspension system for wheeled vehicles, in particular to a suspension system that can operate in two different modes. In order to compromise between optimum ride comfort and optimum road vehicle handling, the present invention provides a dual-mode suspension system in which the main suspension spring rate can be switched between optimum handling and optimum ride comfort.

State of the art

The main purpose of a vehicle suspension is to allow the wheels of the vehicle to move up and down independently over bumps in the road, such as bumps, rather than the entire vehicle with passengers. When the passengers are not directly affected by the bumps in the road, the comfort of the passengers during the journey is greatly improved. Driving only the wheels, rather than the entire vehicle, into bumps in the road saves a significant amount of energy. In addition, as the speed increases, the controllability of the vehicle is greatly improved, since the mass of the entire vehicle as a whole does not bounce when it encounters bumps in the road.

Vehicle suspension can be configured in a number of ways, but typically it is configured to isolate the vehicle's main body, referred to as the "sprung mass", from the wheel systems, referred to as the "unsprung mass", by means of an energy storage means, typically some or springs. The spring accumulates energy, while the wheel system, containing the hub, brake and movement control levers, can move relative to the main body of the vehicle when hitting bumps in the road. After passing the bump, the spring releases the stored energy to return the wheel system to its original position. To avoid uncontrolled vibration, some type of damping device is used as a reaction to the action of a simple spring-mass system. Typically, the hydraulic component creates a force proportional to the speed to produce a resistance force acting in both directions of spring travel and therefore reduces the spring displacement speed to zero at rest. Said damper is an auxiliary suspension component because it cannot support the mass of the vehicle.

When approaching the limits of the dynamic characteristics of the vehicle, the suspension system, containing the control levers of the movement, as well as energy storage and damping components, becomes a limiting factor preventing the achievement of an optimal level of comfort. If the springs and dampers move gently enough (providing a high level of passenger isolation from road irregularities), the sprung mass moves too much as a result of the lateral and longitudinal forces that arise when the driver turns the steering wheel, and also presses the gas and brake pedals. This response is generally referred to as "handling responsiveness" and the quality of the passenger's isolation from road bumps is referred to as "movement sensitivity".

By changing the spring rate and damping coefficients on each of the four wheels at the corners of the vehicle, the ride and handling characteristics of the vehicle can be optimized. In general, higher spring rate, measured in force per unit of displacement, provides a more stable ride and excellent vehicle handling, while softer suspension springs provide a "softer" ride but less handling. Damping coefficients are usually chosen depending on the stiffness. Unfortunately, optimal travel feel is achieved with lower spring rates, while optimum steering response is achieved with higher spring rates. Thus, vehicle designers were forced to find a compromise between the sensitivity of the movement and the responsiveness of the control.

A large number of dual-mode adaptive manual suspension systems have been described in the art. However, to date, none of them has been able to provide the required performance of high performance vehicles using metal energy storage devices such as coil springs, leaf springs, or torsion springs.

Document PCT/US2017/012588, Holt et al., describes a selectively switchable dual mode suspension system. Driven by the pusher, the internal spring mechanism contains a torsion bar and a spiral spring arranged in series, having their own rigidity. A blocking actuator is located parallel to the spiral spring. In the first mode, the coil spring is free to move, so that the total stiffness consists of the stiffness of the torsion bar and the stiffness of the coil spring. In the second locking mode, the coil spring cannot move, thereby changing the overall stiffness to that of the torsion bar. This selectively provides both a comfortable adjustment for optimum ride height with low stiffness and an optimum handling adjustment for low ride height. Although this selectively switchable two-mode suspension system is very efficient, the use of a pushrod mechanism limits its use mainly to vehicles with very high dynamic performance. Thus, there is a need for a selectively switchable dual-mode suspension system that can be used in a wider range of vehicles.

A number of attempts have been made to design more generally applicable dual-mode suspension systems. However, none of them is an active selective shifting system that provides a reduced ground clearance in an optimal driving mode with a high spring rate. For example, US 2009/0302559, Doerfel, describes a non-manually adjustable design with two coil springs arranged around a strut. The spring assembly comprises a main spring, a guide, an abutment and at least one auxiliary spring connected in series with the main spring. During compression of the spring assembly, when the auxiliary spring is compressed to a certain point, the stop contacts the guide to prevent further compression of the auxiliary spring. A description is also given of another design with springs connected in parallel. US 9,162,548, Wakeman, and US 9,821,621, Mason, describe similar designs. Neither of the two designs provides complete blocking of one spring. Mason, in general, suggests maintaining the ride height, while Wakeman suggests the possibility of increasing the ride height from idle or neutral without reducing it. Neither of the two designs contains a means of lowering the ride height in the optimal control mode with high spring rates.

Disclosure of invention

According to the main aspect of the invention, a selectively switchable dual-mode vehicle suspension system comprises a spring structure oriented between the unsprung mass and the sprung mass of one corner of the vehicle and comprising a cylindrical damper, a main coil spring with a first predetermined spring stiffness K1 and an auxiliary coil spring with a second predetermined stiffness K2 springs, wherein the coil springs are arranged in series around the cylindrical damper, creating a common spring constant KT, an actuator configured to compress and decompress the coil springs, a stop configured to disable the auxiliary coil spring at the place where the stop is installed, so that, when the system is in the first comfort mode, the total spring rate of the vehicle suspension is given by the sequence equation 1/KT = 1/K1 + 1/K2 and when the system is in the second control mode, the total spring rate of the vehicle suspension is given by the sequence equation KT = K1 , thereby providing selectively switchable both low stiffness, providing optimal ride comfort settings, and high stiffness, providing optimal handling settings and lower ride height.

According to another aspect of the invention, the main coil spring and the secondary coil spring are connected to an intermediate spring seat.

According to another aspect of the invention, the actuator actuates the secondary coil spring via the lower spring seat.

According to another aspect of the invention, the actuator comprises a hydraulic cylinder and a hydraulic piston.

According to another aspect of the invention, the auxiliary coil spring is rendered inactive when released.

According to another aspect of the invention, the intermediate spring seat comprises a hydraulic cylinder with a hydraulic piston.

According to another aspect of the invention, the auxiliary coil spring is rendered inoperative when compressed.

According to another aspect of the invention, the hydraulic cylinder moves along the outer wall of the cylindrical damper.

According to another aspect of the invention, the abutment comprises a thrust portion of the outer wall of the cylindrical damper against which the contact portion of the hydraulic cylinder abuts.

According to another aspect of the invention, the suspension system further comprises a blocking means configured to hold the auxiliary coil spring in place of the stop.

According to another aspect of the invention, the suspension system further has a third maneuvering mode in which the secondary coil spring is decompressed and the main coil spring is raised to increase ground clearance beyond the optimum vehicle ride comfort setting.

According to another aspect of the invention, the cylindrical damper provides adjustable damping to match changes in spring rate for optimum comfort and vehicle control.

Brief description of the drawings

In FIG. 1A shows a front single acting cylinder assembly mounted in a conventional double wishbone suspension system for use in one corner of a vehicle, typically the front corner, in perspective view;

in fig. 1B, 1C, and 1D are perspective views of the single-acting cylinder front assembly from various angles;

in fig. 2A - part of the mechanism of the single-acting cylinder, a view in vertical section;

in fig. 2B is a perspective view of part of the single acting cylinder mechanism and certain damper components;

in fig. 3A, 3B, and 3C are single-acting front mechanism cylinder assemblies in multiple heights mounted in a conventional double wishbone suspension system, respectively, in lowered, balanced, and raised vehicle height configurations;

in fig. 4A and 4B are front single acting cylinder assembly in low vehicle height configuration, vertical sectional and top view;

in fig. 4C and 4D are front single acting cylinder assembly in vehicle height balanced configuration, vertical sectional view and top view;

in fig. 4E and 4F are front single acting cylinder assembly in raised vehicle height configuration, vertical sectional view and main view;

in fig. 5A is another perspective view of a double-acting cylinder front mechanism assembly;

in fig. 5B is the front mechanism of the double-acting cylinder assembly of FIG. 5A is an enlarged perspective view;

in fig. 5B shows the assembly of the double-acting cylinder of FIG. 5A, another angle, enlarged view;

in fig. 6 - part of the double-acting cylinder mechanism, vertical section view;

in fig. 7A is another version of the front mechanism of the double-acting cylinder assembly installed in a conventional double wishbone suspension system, vertical sectional view;

in fig. 7B is another perspective view of a double-acting cylinder front mechanism assembly.

Implementation of the invention

Embodiments, examples, and options from the preceding paragraphs, the claims, or the writings below, including various aspects thereof or respective individual features, may be used alone or in combination. Features described with reference to an embodiment may be used in all embodiments as long as such features are not incompatible.

In the first embodiment, the suspension system 1 comprises a front mechanism 3 of a single-acting cylinder assembly. In a conventional system of independent double wishbone suspension 7, shock absorption is provided by a cylindrical damper 5 or a strut. In contrast to the conventional strut mechanism with a single coil spring mounted coaxially around the strut, in the embodiment under consideration, two coil springs having different stiffnesses are sequentially coaxially mounted around the cylindrical damper 5 or strut. These springs are a main coil spring 9 with a stiffness of K1 and an auxiliary coil spring 11 with a stiffness of K2. To connect two helical springs 9, 11 is a common support 13 of the spring. At the free end 16 of the column 5, the main coil spring 9 is connected to the upper support 15 or abuts against it. The lower support 17 of the spring is connected to the auxiliary coil spring 11 or abuts against it at a distance from the common support 13 of the spring.

In a spring system containing two springs connected in series, the overall stiffness factor KT is determined from the equation 1/KT = 1/K1+ 1/K2.

Between the lower support 17 of the spring and the non-free end 21 of the cylindrical damper 5, an actuator 20 with a hydraulic cylinder is installed around the said cylindrical damper 5. While a preferred hydraulic ram actuator has been described, the actuator may be any suitable mechanism, including electric, pneumatic, or other mechanism.

When the sub-coil spring 11 is fully extended so that the lower spring seat 17 rests on the suspension components 23 below and the actuator 20 is retracted, the sub-spring 11 has no effect on the overall stiffness coefficient KT. Under these conditions, the coefficient of constant K2 of the auxiliary spring drops out of the equation, so that the spring constant is given by 1/KT = 1/K1. This corresponds to a stiffer suspension, since the combined spring constant of the two springs in series is always lower than that of a single spring taken from the two said springs. It also corresponds to a lower ground clearance for optimal handling in road conditions such as a flat motorway or race track. This reduced ground clearance option is shown in FIG. 3A, 4A and 4B.

When the actuator 20 extends under the action of hydraulic pressure, it compresses the auxiliary coil spring 11 until, at a certain moment, the spring seat 13 breaks away from the spring stop 12, and the auxiliary coil spring 11 again begins to influence the total spring constant according to formula 1/KT = 1/K1 + 1/K2. This corresponds to a less stiff suspension for optimum ride comfort, most suited to rougher road conditions. This mode also increases the vehicle's ground clearance in rougher road conditions. Said comfort ride height or balanced mode is shown in FIG. 3B, 4C and 4D.

Under normal distribution road conditions, optimal ride comfort and height settings, or a balanced mode, can be selected by locking the actuator 20 in a certain position relative to the cylindrical damper 5. In the hydraulic actuator 20 shown, this is achieved by closing the valve 25 to stop the flow 27 hydraulic fluid into and out of the actuator 20.

The actuator 20 may include a hydraulic cylinder 19, hermetically connected to the hydraulic piston 29 with the possibility of sliding, which, in turn, is tightly connected to the outer wall of the cylindrical damper 5 with the possibility of sliding. The position of the hydraulic piston 29 is determined by the volume of hydraulic fluid in the hydraulic chamber 33 bounded by the inner wall 35 of the hydraulic cylinder 19, the outer wall 31 of the hydraulic damper 5 and the piston 29. The piston 29 can contact the lower spring seat 17 so that the hydraulic piston 29 and the lower spring seat 17 reciprocate relative to the cylindrical damper 5. As stated above, the seals 39 prevent hydraulic fluid from flowing out between said components while allowing reciprocation with relatively little friction. The valve 25 may be closed to fix the volume of hydraulic fluid in the hydraulic chamber 33 to lock the actuator 20 in position in the balanced mode of the suspension system.

For certain purposes of maneuvering the vehicle, the ground clearance of the vehicle should be further increased as an advantage. For example, if the vehicle must descend a steep access road to enter a highway, the additional vehicle ground clearance may be useful in preventing vehicle components from contacting the access road or road surface. In this situation, the actuator 20 may further extend to raise the front of the vehicle. In said additional raised position, the system may be referred to as the maneuvering mode shown in FIG. 3C, 4E and 4 F. This does not mean that the vehicle must move at a significant speed, but in certain conditions this option is a useful solution.

In the second embodiment shown in FIG. 5A - 5C, 6 and 7A - 7B, the system contains the front mechanism of the double-acting cylinder assembly. As in the first embodiment with the single-acting cylinder mechanism, the suspension system of the second embodiment comprises a cylindrical damper 5 with main and auxiliary coil springs 9, 11 connected in series and mounted coaxially around the cylindrical damper 5. However, in this embodiment, the spring support 13, connecting the coil springs 9, 11 also includes a reciprocating cylinder 41 that moves along the cylindrical damper 5. In addition, the auxiliary coil spring 11 is attached at the distal end of the spring support 13 relative to the suspension components 23 to which the cylindrical damper 5 is attached. Thus, the compression or expansion of the springs 9, 11 from the place between the springs is provided by the hydraulic cylinder 41.

The hydraulic cylinder 41 is installed so that it reciprocates along the section of the outer wall 37 of the cylindrical damper 5. Hydraulic chambers are located on each side of the piston between the hydraulic cylinder 41 and the outer wall 37 of the cylindrical damper 5. Due to the supply of hydraulic fluid to one of the hydraulic chambers 43, 45, the hydraulic cylinder 41 is forcibly moved in one direction along the cylindrical damper 5. In the embodiment shown, the increase in hydraulic fluid pressure in the first hydraulic chamber 43 forces the hydraulic cylinder 41 to compress the main coil spring 9 and increases the ground clearance vehicle. Conversely, an increase in the pressure of the hydraulic fluid in the second hydraulic chamber 45 forces the hydraulic cylinder 41 to compress the auxiliary coil spring 11 and reduces the ground clearance of the vehicle. When the vehicle's ground clearance becomes low enough, the valve 25 can be closed to stop further flow of hydraulic fluid into the hydraulic chambers 43, 45. This locks the hydraulic cylinder 41 against the cylindrical damper 5, and as it is kept from moving, the auxiliary coil spring 11 is also blocked. so that it cannot influence the total spring stiffness KT. In this optimal control mode, the total stiffness KT of the springs is equal to the stiffness K1 of the main coil spring, and the stiffness of the springs is given by 1/KT = 1/K1.

When the valve 25 is open and the auxiliary coil spring 11 can again influence the total spring rate according to the formula 1/KT = 1/K1 + 1/K2. In this balanced mode, which is the optimal comfort mode, the hydraulic cylinder 41 moves freely in the longitudinal direction due to the compression of the main and auxiliary coil springs 9, 11, the hydraulic fluid flows freely between the first and second hydraulic chambers 43, 45, and the ground clearance remains greater than the clearance in optimal control mode.

An abutment 47 may be provided on the outer wall 37 of the cylindrical damper 5 to abut the contact portion 49 of the hydraulic cylinder 41. The contact portion 49 abuts against the abutment 47 of the wall when a sufficient amount of hydraulic fluid is forced into the first hydraulic chamber 43, which increases the ground clearance of the vehicle. The mode of maneuvering at said increased ride height can be maintained by closing the valve 25 to again stop the flow of hydraulic fluid between the first and second hydraulic chambers. 43, 45.

It should be noted that an adjustable damping system is very useful when used in conjunction with the described suspension system to compensate for changes in spring rate and ride height.

It should also be understood that while a particular arrangement of components is described in the illustrated embodiment, other arrangements may be envisaged. While specific sequences of steps have been described and claimed, it should be understood that the steps may be performed in any order, individually or in combination, unless otherwise indicated, while still providing the benefits of the present invention.

While the various examples contain specific components shown in the drawings, embodiments of the present invention are not limited to these particular combinations. It is possible to use some components or features from one of the examples in combination with features or components from another of the examples.

Despite the exemplary embodiment described, one of ordinary skill in the art will appreciate that certain modifications may be made within the scope of the appended claims. For this reason, the following claims should be examined to determine their true scope and content.

Claims (17)

1. Selectively switchable two-mode vehicle suspension system, configured to orient between the unsprung mass and the sprung mass of one corner of the vehicle, and comprising: cylindrical damper; a main coil spring with a first predetermined spring rate K1 and an auxiliary coil spring with a second predetermined spring rate K2, the coil springs being connected to a common spring seat and arranged in series around the cylindrical damper to provide a common spring rate KT; an actuator mounted on the damper and configured to compress and decompress the coil springs, thrust means configured to disable the auxiliary coil spring in at least one stop installation location, so that when the system is in the first mode, the total spring rate of the suspension is given by the sequence equation 1/KT = 1/K1 + 1/K2 and when the system is in the second mode, the total spring rate of the vehicle suspension is given by the sequence equation 1/KT = 1/K1, thereby providing selectively with the possibility of switching both low stiffness, providing optimal settings for comfortable movement in the first mode, and high stiffness, providing optimal handling settings and lower ground clearance. 2. Suspension system according to claim 1, wherein the actuator comprises a hydraulic cylinder and a hydraulic piston. 3. Suspension system according to claim. 2, in which the hydraulic cylinder moves along the outer wall of the cylindrical damper. 4. Suspension system according to claim 3, in which the thrust means comprises a thrust section of the outer wall of the cylindrical damper against which the contact section of the hydraulic cylinder abuts. 5. Suspension system according to any one of paragraphs. 1-4, wherein the actuator is capable of acting on the secondary coil spring via the lower spring seat. 6. Suspension system according to any one of paragraphs. 1-5, in which the auxiliary coil spring, when released, is rendered inoperative. 7. Suspension system according to any one of paragraphs. 1-6, further comprising a third maneuvering mode in which the secondary coil spring and the main coil spring are compressed outside the first mode to increase the vehicle's ride height above the ride height at the optimum ride comfort setting in the first mode. 8. Suspension system according to any one of paragraphs. 1-3, in which the actuator comprises a common spring seat. 9. The suspension system of claim. 8, wherein the stop means comprises a blocking means configured to hold the secondary coil spring at a plurality of selected stop locations. 10. The suspension system of claim 9, wherein the blocking means comprises valve means for preventing hydraulic fluid from flowing into the hydraulic cylinder. 11. Suspension system according to any one of paragraphs. 8-10, further comprising a third maneuvering mode in which the secondary coil spring is decompressed and the main coil spring is raised to increase the vehicle's ride height beyond the first mode's optimum ride comfort setting. 12. Suspension system according to any one of paragraphs. 1-11, in which the cylindrical damper provides adjustable damping to match changes in spring rate for optimum comfort and vehicle control.