Vehicle fenders – Buffer or bumper type – Bumper having lever and shock absorber mount
Reexamination Certificate
1998-03-23
2001-02-06
Pape, Joseph D. (Department: 3612)
Vehicle fenders
Buffer or bumper type
Bumper having lever and shock absorber mount
C293S002000, C293S005000
Reexamination Certificate
active
06183025
ABSTRACT:
This invention relates to a bumper assembly for a road vehicle such as a rigid or articulated lorry, a passenger coach, a bus or a van and, more particularly, to a sensing arrangement for use with the bumper assembly.
Because of accidents involving vehicles with high ground clearance, it has been recommended practice to fit a rigid bumper bar to such vehicles so as to prevent smaller vehicles such as passenger cars from being forced underneath the large vehicles in an accident. Legislation requires vehicles of a certain minimum weight to be fitted with such rigid bumper bars at a specified height beneath the rear of the vehicle.
One proposed road vehicle bumper assembly comprises a beam which is supported by a pair of arms from the vehicle in such a manner that the beam is displaceable from a rest position in a direction towards or beneath the vehicle in the event of contact with an obstacle. Springs are provided for biasing the beam towards its rest position. The bumper assembly includes sensors for detecting displacement of the beam and activating a warning device.
One disadvantage of this proposed bumper assembly is its susceptibility to damage when the vehicle moves over surfaces of changing incline. In particular, when a vehicle leaves a ferry, it travels down an inclined ramp and then up an inclined road surface. At the junction of the two inclined surfaces, the bumper assembly tends to hit the ground, and this can damage the bumper assembly.
The problem is addressed by a bumper assembly which is the subject of published British Patent No. 2122551.
The said patent specification describes a bumper assembly for a road vehicle which can prevent under-running of smaller vehicles, and which has a reduced chance of accidental damage during operation of the vehicle.
In particular, the invention of published British Patent No. 2122551 relates to a road vehicle having a bumper assembly fitted thereto, the bumper assembly comprising a beam which is pivotally supported by an arm from the vehicle so that the beam is displaceable from a rest position in a first direction towards or beneath the vehicle in the event of contact with an obstacle, spring means for biasing the beam towards its rest position, and means for holding the beam in its rest position, the holding means exerting a force on the beam so as to prevent the beam being displaced in a direction opposed to said first direction, unless the beam is subjected to a predetermined force, wherein a hollow rubber spring constitutes the spring means.
The same patent also relates to a road vehicle having a bumper assembly fitted thereto, the bumper assembly comprising a beam which is pivotally supported by an arm from the vehicle so that the beam is displaceable from a rest position in a first direction towards or beneath the vehicle in the event of contact with an obstacle, spring means for biasing the beam towards its rest position, and means for holding the beam in its rest position, the holding means being such as to prevent the beam being displaced in a direction opposed to said first direction, unless the beam is subjected to a predetermined force, wherein a hollow rubber spring constitutes said spring means. Preferably, either of the bumper assemblies further comprises sensing means for detecting displacement of the beam and activating a warning device.
Thus, when the vehicle is being manoeuvred in restricted conditions, the bumper assembly is likely to be the first part of the vehicle which touches an obstacle; and, after being displaced a short distance (which will not damage the obstacle or the vehicle), an audible or visual warning will be activated so that the driver will be immediately aware that his vehicle is in contact with an obstacle.
In general, the beam will be displaceable through a predetermined distance. Thus, in the event of collision with another vehicle, there will be a deceleration effect during which the spring means of the bumper assembly will absorb some of the energy of impact. Thereafter, the beam will meet a stop position on the vehicle, which will prevent a smaller vehicle from penetrating beneath the larger vehicle.
In a preferred embodiment of British Patent No. 2122551, the sensing means is a magnetic Reed switch which comprises a permanent magnet, a sensing device responsive to the magnetic field of the permanent magnet, and a shield which is positionable between the magnet and the sensing device to prevent the sensing device being influenced by the magnetic field of the magnet, wherein the magnet and the sensing device are fixed to a stationary part of the assembly, and the shield is fixed to a movable part of the assembly. Advantageously, the shield is arranged to pivot with the arm as the beam is displaced from its rest position.
The arm may be pivotally supported from the vehicle by a mounting channel fixed to the vehicle and a pivot pin which is fixed to the mounting channel, the arm being pivotally mounted on the pivot pin. In this case, the shield may be fixed to the arm for rotation therewith. Preferably, the shield is a sector-shaped member made of magnetic material.
Advantageously, a hollow rubber spring constitutes the spring means. The hollow rubber spring may be fixed to an internal flange of the arm, in which case the mounting channel may provide an abutment for the hollow rubber spring.
In a preferred embodiment of the above-mentioned Patent, the holding means is constituted by a second spring means, the second spring means being positioned so as to bias the beam towards its rest position in the opposite direction from that in which the first spring means biases the beam towards its rest position.
Advantageously, the second spring means is preloaded so that, when the beam is in its rest position, the first-mentioned spring means is subjected to a compressive load. The second spring means may be a hollow rubber spring which is positioned within the arm between a flange fixed within the arm and a retaining plate.
Preferably, a transmission element is detachably fixed to the pivot pin for rotation therewith, and the retaining plate is provided with a link which is pivoted to the transmission element.
Advantageously, the warning device is a bleeper unit. Preferably, the sector-shaped shield is such that the bleeper unit is activated when the beam is displaced from its rest position in said first direction through a first predetermined angle, and whenever the beam is displaced from its rest position in a second direction opposed to said first direction through a second predetermined angle. In a preferred embodiment, the sector-shaped shield is such that said first predetermined angle is substantially 2° mid said second predetermined angle is substantially 74°.
While the above-mentioned assembly has been found to perform its intended function well the reed switch of the sensing means needs to be located in the vicinity of the bumper assembly, often at a location proximate to a pivot arrangement which is provided for allowing the arms to move with respect to the stationary part of the assembly. Since the bumper assembly is subject to typically harsh operational environments, in particular when fitted to a commercial vehicle, the sensing means must also be capable of enduring such harsh environments. The sensing means is potentially vulnerable to damage through abuse, vibration or climatic conditions.
Some protection may be provided by housing the sensing means, in the above case the reed switch, within an enclosure, but this can lead to a more complicated replacement procedure and may extend repair times when working on the assembly which is undesirable for commercial vehicles.
Other types of sensors including mechanical, solid state, semi-conductor or optical devices may be considered as alternatives to the reed switch based sensing means. However, they also normally need to be located in the vicinity of the bumper assembly for operation, and the above-mentioned problems will not necessarily be obviated. Mechanical contact based switches may also be undesirable when used in environment
Hope Frederick John Charles
Hope Robert James
Burns Doane Swecker & Mathis L.L.P.
Hope Technical Developments Limited
Pape Joseph D.
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