The invention relates to the suspension of vehicle wheel, especially of vehicle for rough terrain driving, comprising a helical spring arranged between two members of wheel suspension.
The wheels of wheeled vehicles are towards the vehicle chassis mounted on suspensions, whose task is to provide for the vehicle towards the driving surface a support, which enables a springy and simultaneously damped mounting of the spring loaded section of the vehicle towards the terrain, and as regards the driving wheel, it secures transmission of the driving force to the driving surface.
Each suspension is formed of a kinematic system of rigid bodies, which ensures a definite guidance of the wheel towards the vehicle chassis, and of springy and damping means, which ensure a dynamic transmission of force reaction being induced between the driving surface and the travelling wheel on the vehicle chassis. There exists a great number of kinematic schemes in suspension of wheels. The currently used suspensions, for example the parallelogram, trapezoidal, telescopic (McPherson), pendulous, crank, angle, are characterized by both positive and negative specific characteristics. The basic requirement is the minimum change in geometry of undercarriage at springing action, i.e. at deflection of suspension from the nominal position. These are mostly the changes in wheel gauge and in wheel base and the change in position of the side plane of the wheel with respect to the vertical longitudinal symmetry plane of vehicle.
At vehicles designated for driving on roads the change of these parameters is small, which is given by low values of expected springing action. Minor driving surface irregularity does not required application of springy and damping means featuring great travels, while the extreme positions of suspensions towards the vehicle chassis are then defined by means of bump stops.
Other situation is at vehicles destined for operation outside the roads in a free terrain, where a great travel in suspension is one of the basic required characteristics of the vehicle undercarriage. Geometry of kinematic arrangements of the known types of suspensions by itself enables the great travel without problems. The limiting elements in this section of undercarriage is the spring of suspension and shock absorber of suspension, quite frequently these means are being integrated into the springy and damping unit.
Extreme positions of the axle are illustrated on an example of the crank suspension of the rear rigid axle being suspended by means of a central springy and damping unit mounted in vertical longitudinal symmetry plane of a terrain vehicle (
In principle, the background art uses two solutions of this problem.
The first design at the same positioning of the lower end of the springy and damping unit on the crank of the suspension utilises a long spring with a greater number of coils. Having not changed diameter of the wire and the spring, its rigidity is reduced which at the same time enables a greater travel. Nevertheless the long spring is unstable in side direction, which complicates the stress of material and reduces the spring life. Simultaneously, mounting of an upper end of the long springy and damping unit causes the structural problems from the point of view of requirements as to space.
The second solution utilises a short spring. In this case it is necessary to transfer the connection of the lower end of the springy and damping unit to the crank of the suspension closer to axis of crank swinging. In this case the stress of the spring increases substantially, therefore the spring must be made of a thicker wire. High rigidity of the spring increases bending stress of the crank, which must be more dimensioned. Through this the unsprung mass of axle is increased with all negative consequences as to controlling comfort. None of these solution remedies the basic problem, which is the loss of adhesion and thus loss of the propulsive effect of the axle in area of maximum length of springy and damping unit, when the force produced by the spring is the smallest. On the contrary, in the area of minimum length of the springy and damping unit the forces transferred into the structure of vehicle are extremely great and require a huge dimensioning of the adjacent parts of vehicle.
The goal of the invention is to eliminate or at least reduce shortcomings of the background art, first of all through the structural arrangement to better use the possibilities, which are provided by the spring for springing of a vehicle.
The goal of the invention has been achieved by the suspension of vehicle wheel comprising the helical spring, whose principle consists in that, one end of the spring is coupled with moveable member of the wheel suspension, and the second end of the spring is coupled with the controlled member of rolling kinematic couple, whose rolling surface engages with convex rolling surface of the controlling member of the rolling kinematic couple, which is mounted on the basic member of the wheel suspension.
The moveable member is for example the crank of the crank suspension or the lower arm of parallelogram suspension, whereas the basic member, as a rule, is connected with the vehicle chassis. This arrangement simplifies the structure of the moveable member, at the same time mounting of the controlling member of the rolling kinematic couple on the basic member, which in this case is substantially immovable, is simple as well.
The goal of the invention has also been achieved by the suspension of vehicle wheel comprising the helical spring, whose principle consists in that, one end of the spring is coupled with the basic member of wheel suspension and the second end of the spring is coupled with the controlled member of the rolling kinematic couple, whose rolling surface engages with convex rolling surface of the controlling member of the rolling kinematic couple, which is mounted on the moveable member of the wheel suspension.
This solution reduces the unsprung mass of vehicle and simultaneously reduces the demand as to space. Preferably, the moveable member is the crank of the crank suspension.
The controlling member of the rolling kinematic couple is on the basic or moveable member of the wheel suspension mounted in a fixed manner, which is simple from the design point of view.
The controlling member of the rolling kinematic couple in an alternative embodiment on the basic or moveable member is mounted in a moving manner, through which a greater travel of wheel with respect to the vehicle chassis is achieved.
In case of moveable mounted controlling member of the rolling kinematic couple it is advantageous, if this controlling member is coupled with another member of the wheel suspension to derive its motion with respect to the member of the suspension, on which the controlling member is mounted. It is especially advantageous, if for this purpose it is coupled with individual propulsion. Through a controlled motion of the controlling member of the rolling kinematic couple there may be achieved an optimum course of spring compression, by means of which either the vehicle spring suspension for various types of driving surfaces may be adjusted, or continuously during driving the sprung parts of vehicle may be maintained in the desired stabilised position.
Preferably, in the sophisticated embodiment, the individual propulsion serving to derive motion of the controlling member of the rolling kinematic couple is controlled by a system of automatic control of stabilised position of the vehicle parts coupled with the basic member. This enables to maintain a stable, usually horizontal position of the vehicle chassis.
The controlled member of the rolling kinematic couple is a rack bar, whose rolling surface engages with convex rolling surface of the controlling member of the rolling kinematic couple, whereas the convex rolling surface is a toothed one. In this case the controlling member is the tooth wheel or at least its segment.
It is also preferred, if the controlled member of the rolling kinematic couple is a flexible member, whose rolling surface engages with convex rolling surface of the controlling member of the rolling kinematic couple, while the shape of surface respective to the convex rolling surface corresponds to the shape of surface of the corresponding rolling surface of the flexible member, and the flexible member is attached with its end to the convex rolling surface of the controlling member.
At motion of the moveable member of suspension with respect to the member on which it is mounted, the flexible member is being wound on the convex rolling surface of the controlling member, which reduces demand as to installation space of the suspension.
It is also preferred, when a mutual tangent position of the rolling surface of the controlled member of the rolling kinematic couple and the convex rolling surface of the controlling member of the rolling kinematic couple is ensured through a linear guidance. This, especially in some embodiments enables geometrically perfect engagement of the controlling and controlled member of the rolling kinematic couple.
The principle advantage of the solution according to the invention is increase in travel of the vehicle wheel while preserving the adhesion without increasing the structural length of the spring due to interaction of members of wheel suspension mechanism with the rolling kinematic couple. Through a suitable shaping and propulsion of the controlling member of the rolling kinematic couple the controlled compression of the spring may be secured, and thus also a controlled course in characteristics of great travel of the suspended wheel at driving over a rough terrain. In most embodiments the suspension is of a compact, technologically advantageous shape with minimum demand as to installation space and the forces through which the suspension acts towards the vehicle chassis are concentrated into sufficiently dimensioned parts of vehicle.
Exemplary embodiments of arrangement of the vehicle wheel suspension and its springing are schematically represented in the drawing where the figures “a” represent the suspension position before the wheel drives over the elevation of the driving surface, and the figures “b” position of suspension at the moment when the wheel is on elevation of the driving surface, whereas the travel of the driving wheel is marked in compliance with numbers of figures “H1” to “H7”. The
The
The spring-loaded crank suspension 1 comprises the moveable member 2 formed of body 21, which on one of its end carries the shaft of controlling wheel 3 and with its second end it is mounted on the basic member 4 in a swinging manner around axis 41. Inside the body 21 there is mounted the springy and damping unit formed of compression helical spring 11 and of fluid shock absorber 12 arranged axially with the spring 11, while the cylinder 13 of the fluid shock absorber 12 is connected with the body 21. The compression helical spring 11 with its end adjacent to the wheel 3 is resting against the fixed support 14 attached in the body 21 of the spring-loaded crank suspension 1. The second end of the spring 11 is in contact with the shifting support 15 in a fixed manner connected with the piston rod 16 of the fluid shock absorber 12, which is in a fixed manner connected with the rack 17 in a sliding manner mounted in the linear guidance 18 in the body 21 of the spring-loaded crank suspension 1. On the basic member 4 in a fixed manner is mounted the gear segment 42, whose axis is identical with the axis 41 of the swinging motion of the body 21 towards the basic member 4. The rack 17 engages with its gearing with gearing of the gear segment 42.
The gear segment 42 functioning as the controlling member 101 and the rack 17 functioning as the controlled member 102 form the rolling kinematic couple, whereas the gearing of the segment 42 represents its convex rolling surface 5.
In position of the wheel 3 before a protruding terrain unevenness the spring 11 is of maximum or nearly maximum length, and the shifting support 15 together with the piston rod 16 of fluid shock absorber 12 and the rack 17 in the body 21 is in vicinity of the extreme position on the side adjacent to the basic member 4. Upon driving of the wheel 3 up a bump having height H2, the wheel 3 due to generated reaction force is pressed in direction upwards and it performs a vertical travel H2 with respect to the basic member 4. At the same time the rack 17 rolls along the gear segment 42 and simultaneously inserts the piston rod 16 of the fluid shock absorber 12 into cylinder 13 of the fluid shock absorber 12 and by means of the shifting support 15 compresses the spring 11. The force of the spring 11 is being increased till the moment of balance in dynamic force of the body 21. The dependence of force of the spring 11 on an angle position of the body 21 of the spring-loaded crank suspension 1 forming the crank of the suspension is uniquely given by characteristic of the spring 11 and by kinematic dependence of axial position of the rack 17 on the angle position of the body 21. This dependence may be determined from transmission of the rolling kinematic couple, whose controlling member 101 is the gear segment 42 and the controlled member 102 is the rack 17.
In the not represented embodiment the gear segment 42 and the rack 17 may be superseded by a segment of chain wheel and two-way load carrying chain, whereas the linear guidance 18 is modified in appropriate manner. With its free end the chain is attached to the segment of a chain wheel, with its convex rolling surface it engages. Advantage of this alternative consists in that, the chain is partially wound on circumference of the chain segment and the solution does not require space in the basic member 4, into which in the represented embodiment extends the end of the rack 17.
At the same compression of springs of the springy and damping unit are achieved the travels H1, H2 of the wheel 3 initiated by various heights of unevenness of the driving surface. Comparison of embodiment according to the background art (travel H1,
Arrangement represented in the
Also in this embodiment the gear segment 42 exerts the function of controlling member 101 and the rack 17 the function of controlled member 102 of the rolling kinematic couple, while gearing of the segment 42 represents its convex rolling surface 5.
Applicability of this invention is not limited to cranked suspensions of the driving wheels only. The
Functioning of embodiment according to the
The
The segment 45 here fulfils function of the controlling member 101 of the rolling kinematic couple, and the rope 74 fulfils function of the controlled member 102 of the rolling kinematic couple, while the cylindrical surface of the segment 45 is the convex rolling surface 5.
The segment 45 is firmly connected with the basic member 4. Damping of suspension motion during springing in this embodiment is secured by means of the fluid shock absorber 75, which is an individual member of the suspension mechanism 7. In the given case the fluid shock absorber 75 must be relatively long, so as to cover the whole range H5 of axle travel, which enables the lower spring-loaded arm.
In the not represented embodiment instead of the compression helical spring 71 the draw helical spring is used, which with the end adjacent to the wheel 3 is attached to the body 70 of lower spring-loaded arm and with the second end directly to the rope 74 of the controlled member 102, which is being wound on the continual convex rolling surface of the segment 45 of the controlling member 101.
In alternative embodiments of the rolling kinematic couple as a flexible controlled member 102 the roller chain, or flat belt, vee-belt or toothed belt is used. Segment 45 of the controlling member 101 is then provided with respective convex rolling surface 5 formed of rolling surface of the chain wheel, or of rolling surface of the flat, v-belt or toothed pulley. Segment 45 may be mounted on the basic member 4 rotatably with forced rotation motion, similarly as at the embodiments represented in the
The parallelogram suspension 8 of the wheel 3 represented in the
Here, the controlling member 101 of the rolling kinematic couple is represented by the gear segment 42, and the controlled member 102 of the rolling kinematic couple is represented by the rack 88, while the convex rolling surface 5 is formed of the rolling surface of gearing of the segment 42.
Alternatively, the blind end of the cylinder 83 of the fluid shock absorber 82 instead of with the lower arm 84 of the suspension 8 may be connected, in the not represented manner, for example with the pitman 89 of parallelogram suspension 8 of the wheel 3.
The
In the not represented embodiments the rounded body 98 is of another suitable shape of the convex rolling surface 5 and it is on the crank 99 mounted in a not moveable manner and in another suitable position or rotatably with axis either in the swinging axis 41 of the crank 99, or even outside of it.
In alternative embodiments of the rolling kinematic couple is used as a controlled member 102 the roller chain, or flat belt, vee-belt or toothed belt. The controlling member 101 is after then provided with a respective convex rolling surface 5 formed of a rolling surface of the chain wheel, or of a rolling surface of the flat, vee-belt or toothed pulley.
The rounded body 98 forming the controlling member 101 of the rolling kinematic couple may in another not represented embodiment be realised by means of a gear segment, and the controlled member 102 by the rack, while the linear guidance of the rack similar to the embodiment represented in the
The rounded body 98 as a controlling member 101 and the rope 97 as a controlled member 102 are forming a rolling kinematic couple, whereas the circumferential surface of the rounded body 98 is its convex rolling surface 5.
Similarly as the moveable segments of previous embodiments the rotatably mounted rounded body 98 may as a controlling member 101 of the suspension 9 with respect to the moveable member 2 exercise a relative motion, which is derived e.g. from a relative motion of the moveable member 2 with respect to the basic member 4 by means of the not represented coupling, or it is mediated by the individual propulsion itself.
Non-circular, in exemplary embodiment an elliptic, convex rolling surface 5 enables to reach a variable gear ration between an angle travel of the moveable member 2 and compression of the spring 91. Through this the course of travel characteristics of the crank suspension 9 of the wheel 3 may be affected in a suitable manner.
The advantage of wheel suspensions 3 of a vehicle for driving in a rough terrain in embodiments 1, 6, 7, 8, 9 according to the invention consists in that it enables a great vertical travel of driving wheels of a vehicle at its driving in terrain, while relatively short springs of spring suspension of vehicle may be used. This reduces the demand as to the space at installation of suspension, while the forces transferred from the suspension into the basic member 4 are acting in places which are sufficiently dimensioned.
Through a suitable shaping of the convex rolling surface 5 on the controlling member 101 of rolling kinematic couple, the travel characteristics of vehicle spring suspension may be affected positively in a broad range.
If the controlling member 101 of the kinematic couple provided with a convex rolling surface 5 is equipped with own propulsion, it may be with advantage used as an active member of automatic stability controlling system of the basic member 4 of vehicle and the connected super-structures.
The technological point of view is important as well. The suspensions of vehicle wheels, in embodiment according to the invention mostly create compact installation assemblies, which are installed into a vehicle at simultaneous saving of installation time.
Number | Date | Country | Kind |
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PV 2009-440 | Jul 2009 | CZ | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CZ10/00076 | 7/9/2010 | WO | 00 | 1/6/2012 |