| 1. | Bumper system (1), comprising a plurality of bumpers (la, lb, lc, ld) for mounting onto a chassis (2) of a movable body, in which said bumpers (la, lb, lc, ld) are provided with one or more shock absorbers (3a, 3b, 3c, 3d), characterised in that said shock absorbers (3a, 3b, 3c, 3d) are compressible through collision forces of an impact of said body and restore slowly to their original state after said compression. |
| 2. | Bumper system according to claim 1, characterised in that said shock absorbers (3a, 3b, 3c, 3d) are made from a resilient foam. |
| 3. | Bumper system according to claim 2, characterised in that said shock absorbers are neopolene foam blocks (3a, 3b, 3c, 3d). |
| 4. | Bumper system according to any one of claims 1 to 3, characterised in that said bumpers (la, lb, lc, ld) are slidably mounted over the chassis (2). |
| 5. | Bumper system according to claim 4, characterised in that in the chassis one or more slots (4) are provided in which by means of bolts said bumpers (la, lb, lc, ld) are slidably mounted over the chassis (2). |
| 6. | Bumper system according to claim 5, characterised in that said bolts are countersunk bolts. |
| 7. | Bumper system according to any one of claims 1 to 6, characterised in that said bumpers (la, lb, lc, ld) have a box structure in which the shock absorbers (3a, 3b, 3c, 3d) are brought. |
| 8. | Bumper system according to any one of the preceding claims, characterised in that said bumpers (la, lb, lc, ld) are made of rotation moulded plastic. |
| 9. | Bumper system according to claim 8, characterised in that said plastic is polyethylene. |
| 10. | Bumper system according to any one of the preceding claims, characterised in that said bumpers (la, lb, lc, ld) are provided with a curving (10,11). |
| 11. | Kart provided with a chassis (2) onto which a bumper system (1) according to any of the preceding claims is mounted. |
A kart comprises a bumper system comprising front, rear and side bumpers which are mounted on the chassis of the kart. Until now, rotation moulded bumpers, for instance a plastic cover made of polyethylene (PE), are fixed to a chassis in the form of a steel frame by bolts with some small rubber rings.
The disadvantage of such a system is that, when there is an impact of the kart with other karts or for instance with a wall, the collision forces are completely transmitted to the chassis, and accordingly all the energy is absorbed by the steel frame, which effects in much higher rebound forces. In such a way, high loads and high accelerations are induced to the driver.
To transmit the impact at any one point throughout the bumper system, U. S 5,806, 901 describes a bumper system for a go-kart which has a plurality of bumper sections which have a sufficient rigidity that displacement to one bumper section transmits motion to other bumper sections, and which can effectively dampen the shock experienced during an impact by providing shock absorbers which may be any material or device which provides both a resilient spring effect and a dampening effect, to absorb the impact energy. These shock absorbers are for instance made of rubber.
For the rear bumper system, transverse motions guides are provided to support a rear bumper section, and to maintain various bumper sections about a horizontal plane relative to the frame, while permitting the necessary horizontal motions, both
longitudinally and laterally. The bumper sections may be connected together at their ends by pivots. Alternatively, the bumper sections may be continuous. The bumper sections may be formed from steel or a fibre reinforced composite material.
A first disadvantage of such a system is that when there is an impact of the kart, the kart will be subjected to big rebound forces and is bounced back because of the use of a type of shock absorbers such as rubber. If the kart bounces back directly, accelerations take longer and there is a bigger risk of head injuries.
Further disadvantages of such a system are that first of all, the system is a complex and expensive construction regarding to mounting, and second of all that it is a strongly moving unit because of the great freedom to move of the system. In this way, and in addition with vibrations because of motion, the system is more subjected to wear.
The purpose of the invention is to provide a bumper system, comprising a plurality of bumpers for mounting onto a chassis of a movable body, in which said bumpers are provided with one or more shock absorbers, and a kart provided with a chassis onto which such a bumper system is mounted, in which during an impact the accelerations of the driver are as low as possible, and in which furthermore the energy is absorbed and is not elastically returned by spring back.
The purpose of the invention is achieved by providing a bumper system, comprising a plurality of bumpers for mounting onto a chassis of a movable body, in which said bumpers are provided with one or more shock absorbers, in which said shock absorbers are compressible through collision forces of an impact of said body and restore slowly to their original state after said compression.
By using such shock absorbers, the movable body won't be subjected to big rebound forces and isn't bounced back because of the fact that the shock absorbers first compress through the collision forces of an impact and afterwards restore slowly to
their original state. In this way, the accelerations on the driver of the movable body are very low and the energy is dissipated.
In a preferred embodiment of a bumper system according to the invention, said shock absorbers are made from a resilient foam.
Said shock absorbers are preferably neopolene foam blocks.
In order to achieve a compression of the shock absorbers, in a bumper system according to the invention said bumpers are slidably mounted over the chassis.
Therefore in the chassis one or more slots are provided in which by means of bolts said bumpers are slidably mounted over the chassis.
In this way, a play is created so that the bumpers can move over the chassis when there is an impact of the movable body.
Preferably, said bolts are countersunk bolts.
In this way, the driver of the movable body can't be wounded, and at the underside of the chassis, the movable body can't hook on protrusions in the surface onto which it moves.
In a preferred embodiment of a bumper system according to the invention, said bumpers have a box structure in which the shock absorbers are brought.
Preferably, the bumpers of a bumper system according to the invention are made of rotation moulded plastic.
Said plastic is preferably polyethylene.
In order to protect the movable body from being lifted up when there is an impact, and thus preventing that parts of the body of the driver would be wounded, the bumper system according to the invention is provided with a curving.
Furthermore, the purpose of the invention is achieved by providing a kart provided with a chassis onto which such a bumper system is mounted.
A bumper system for a kart in which this invention is embodied and its manufacture is described now by way of example only with reference to the accompanying drawings, of which: - figure 1 is a view from above of a chassis of a kart over which a bumper system according to the invention is mounted; - figure 2 is a perspective view of a chassis as shown is figure 1 and neopolene foam blocks which are provided in the bumpers of the bumper system as shown in figure 1; - figure 3 is a section according to line A-A as indicated in figure 2; - figure 4 is a side view of a part of a front bumper with a curving from one kart and a rear bumper with a curving from another kart when there is a rear-end collision of the two karts ; - figure 5 is a view from above of a chassis from a kart as shown in figure 1, and further provided with protection for a front and a rear wheel; - figure 6 is a perspective view of a protection of a front wheel as shown in figure 5; - figure 7 is a perspective view of a protection of a rear wheel as shown in figure 5.
As shown in figure 1, a bumper system (1) according to the invention exists out of a front bumper (la), a rear bumper (lb), and two side bumpers, i. e. a left (lc) and a right side bumper (in). The bumpers (la, lb, Ic and ld) are mounted over a chassis (2). The chassis (2) is preferably made out of a composite material manufactured by
RTM-process, although this doesn't exclude any other type of chassis onto which such a bumper system (1) can be mounted.
The bumpers (la, lb, lc and ld) have a box structure in which the shock absorbers are brought.
The box structure of the bumpers (la, lb, lc and ld) is obtained by making the bumpers (la, lb, lc and ld) out of rotation moulded plastic. Rotation moulding is a technique in which in a hollow mould a plastic powder is deposited and afterwards heated while the mould circles around. In this way, the plastic powder melts and becomes liquid, and accordingly goes to the outside of the mould. The plastic is then cured and a bumper (1 a, 1 b, 1 c or 1 d) having a box structure is obtained. The plastic which preferably is used is polyethylene (PE).
It is very important that the shock absorbers are compressible through collision forces of an impact of the kart (which is provided with a chassis (2) onto which a bumper system (1) is mounted) and restore slowly to their original state after said compression. Therefore, a resilient foam is used such as neopolene foam. As is shown in figure 2, in each bumper (la, lb, lc and ld) one or more blocks of neopolene foam with a suitable form are provided. In the front bumper (la) and the two side bumpers (lc, ld), one block (3a, 3c, 3d) of neopolene foam is provided. In the rear bumper (lb), three blocks (3b) of neopolene foam are provided.
As can be seen in figure 3, which is a section of the left bumper (lc) as shown in figure 1, the bumper (Ic) has a box structure in which a neopolene foam block (3c) is provided. The bumper (lc) is slidably mounted over the chassis (2). Therefore, the chassis (2) is provided with one or more slots (4) (as also can be seen in figure 2) in which by means of bolts (not shown on the figure) the bumper (lc) is slidably mounted over the chassis (2). By providing a slot (4), a play is created so that the bumper (lc) can move over the chassis (2) when there is an impact of the kart. The play depends on the kind of bumper (la, lb, Ic or ld) (for instance for front and rear bumpers (la, lb) a slot of 4 cm is provided, while for side bumpers (lc and ld) a slot of 2,5 cm is provided). The bolts that are used are preferably countersunk bolts. In
figure 3, the cavities (5) to bring the countersunk bolts in are shown. By using countersunk bolts, the driver of the kart can't be wounded. Furthermore, at the underside of the chassis, the chassis can't hook on protrusions in the driving surface.
All further bumper (la, lb and ld) are produced and mounted in the same way as this left bumper (lc).
Accordingly, when there is an impact of the kart with an other kart, or for instance a wall or any other obstacle, the neopolene foam block (s) (3a, 3b, 3c or 3d) will quickly compress due to the collision forces which are exerted during the impact, and will then restore slowly to its (their) original state after said compression. In this way, the kart won't be bounced back, and the accelerations of the driver of the kart will be kept low during the collision, through which the risk of for instance head injuries or other injuries will seriously be decreased.
Furthermore, by providing a bumper system (1) according to the invention, the mounting of the bumper system (1) on the chassis (2) happens very quickly, which results in saving a lot of time, and is furthermore easy to execute.
Each bumper (1 a, 1 b, 1 c and Id) is provided with a certain curving, this in order to protect the kart from being lifted up when there is for instance an impact with an other kart. In this way, parts of the body of the driver are protected from being wounded. In figure 4, the curving of a rear (lb) and a front bumper (la) is shown when there is a rear-end collision of two karts. The front of the front bumper (la) has an outwardly curving (10), while the back of the rear bumper (lb) has an inwardly curving (11). The bumpers (la, Ib) have a curving (10,11) in such a way that the bumpers (l a, lb) fit into each other, as can be seen in figure 4. Also the side bumpers have an inwardly curving (not shown on the figures).
In order to protect the wheels of a kart provided with a chassis (2) onto which a bumper system (1) according to the invention is mounted, a protection for the front wheels and a protection for the rear wheels are attached to the bumper system (1), as
is shown in figure 5. The protection (6) for the right front wheel (7) (said protection (6) also shown in figure 6) is attached to the front bumper (la) and a the right side bumper (in). Also the left front wheel is protected with such a protection (is not shown on figure 5). The protection (8) for the right rear wheel (9) (said protection (8) also shown in figure 7) is attached to the right side bumper (ld) and the rear bumper (lb). Also the left rear wheel is protected with such a protection (is not shown on figure 5). These protection (6, 8) are made of HDPE (high density polyethylene), which is a flexible product through which the protections (6,8) adapt the right shape between the bumpers (la, lb, lc, ld). When there is an impact of the kart, the bumpers (la, lb, Ic, ld) slide over the chassis (2) through which one or more of the wheel protections (6, 8) bend outwardly.
An other possibility is to produce the wheel protections (6,8) by means of injection moulding, through which the wheel protections (6, 8) immediately have the correct shape and curving.