The present invention relates to a hinge arrangement for passenger
car hoods, which arrangement intends to decrease the injuries on pedestrians which
are run into, whereby the hood is of the type, which is pivotable about two hinges
applied at the rear end of the hood, and whereby the hood is arranged to yieldingly
absorb impacts in the vertical direction.
A great number of the people who are injured or killed in traffic
are unprotected pedestrians, which are run into by passenger cars. In a collision
between the front of a passenger car and a pedestrian, a common consequence is that
the pedestrian falls over the hood, and the pedestrian's head collides with the
hood vertically from above with high kinetic energy. Investigations have indicated
that head of a grown person probably collides against the hood, principally in the
rear half, while children collide with their heads against the front half. It is
known to design hoods yieldingly to protect pedestrians, and to attempt to increase
the distance from the hood to underlying hard components over different parts of
the hood, i.e. so that a deformation length is obtained, which is sufficient to
completely brake the pedestrian's head before it hits any hard components.
An important problem in this context, which so far not has been solved in a satisfactory
manner, is the fixing of the two hood hinges in those type of hoods where the hinges
are arranged at the rear end of the hood. The risk is comparatively great that an
adult pedestrian being run into hits their head at or close to the rear hinge fixings,
which in conventional constructions are rigidly connected to the car body and therefore
would cause contusions to a head which falls heavily onto the hinge fixing.
One proposed solution is described in German Patent Application DE 19 712 961 A.
According to this proposal there are sensors which detect a collision with a pedestrian,
and thereby activate a compressed spring or release an explosive charge, whereby
said spring or explosive charge lifts the hood above the hinges to form a compliant
deformation length between the hood and the fixed parts in front of the hinges.
This construction, with sensor and compression spring or explosive charge, is particularly
Further the construction according to said German publication has several essential
drawbacks. There is a risk, for instance, that the compression spring or explosive
charge is released unintentionally, for instance in another type of collision. Upon
an unintentional release it is longwinded and time demanding to re-establish the
release device. A further drawback is that there is a risk that upon collision,
the rear elevated hood is displaced backwards by horizontal forces into the windshield,
with accompanying risk for driver and passengers.
In German publication 27 11 339 a device is described in which the
hood is lifted up above the rear fixings of the hood, in connection with a collision
at which the hood is displaced backwards. Apart from that this publication does
not describe a solution for hinges, the construction has a number of drawbacks associated
with the fact that the hood must be displaced backwards, in order to lift the hood
upwards in the rear. An obvious drawback is that a pedestrian which is run into,
may be thrown with his head into the hood at or close to the rear fixings without
the hood being previous displaced backwards, which leads to the person's head hitting
the hard fixings directly. A further drawback is that there is a major risk for
the hood to hit into the windshield if displaced backwards. Passenger car hoods
are compliantly shaped to collision impacts from above and are differently bent
and accuated at different places aiming to create sufficient deformation space between
the hood and the underlying hard components. If the hood is displaced in connection
with a collision, there is no control whatsoever whether the deformation spaces
under the hood are sufficient.
In European Patent 644 104 B1 a similar solution is described. Here
a lifting device is described, being arranged to lift the rear end of the hood when
the hood is displaced backwards during a collision.
Although the problem, such as evident from above, has been known for
a long time, until now no satisfactory solution has been disclosed.
A simple solution has been achieved through the present invention
which completely eliminates the above problem using an arrangement of the type mentioned
in the introductory part.
The arrangement according to the invention is characterised in that
each hinge is respectively fixed in two rods which are interconnected at the hinges,
that one of these rods is a draw rod, being arranged to absorb forces in the longitudinal
direction of the hood and essentially prevent its horizontal displacement in connection
with a collision between the front of the passenger car and another object, such
as a vehicle or a pedestrian, that the second of the rods is a vertical rod, which
is arranged to be deformed at a vertical collision impact during absorption of a
predetermined vertical load and which rod is shaped to be able to absorb said vertical
load through a predetermined deformation length.
It should be observed that the expression "vertical", which is used
here in the description and the patent claims, should be given an interpretation
that is wider than what is normally related to with this expression. The expression
is used to describe that an impact against the hood comes from above. The hoods
of different cars have different inclinations in relation to an absolute vertical
plane. At a collision between a pedestrian and the front of a passenger car the
head of the person will hit the hood in a direction, which relative to the horizontal
plane is less than 90° and usually in the region of 50 °.
The invention will be described in the following with reference to
an embodiment shown in the enclosed drawings, wherein figure 1 schematically shows
the front half of a passenger car from the side and upon a collision with a person.
Figure 2 shows schematically a plan view of the front half of the car according
to figure 1. Figure 3 schematically shows the principle of the solution according
to the present invention.
Figure 4 shows the principle of the absorption of horizontal load by the hinge
Figure 5 shows the hinge fixings according to figure 4 after deformation in connection
with a vertical load. Figure 6 shows a side view of an embodiment of a device according
to the invention.
Figure 1 shows how a pedestrian, who is run into by the front 1 of
a passenger car 2 falls over the hood 3. The forward bumper has, in the drawing,
been marked with 4, and the windshield of the vehicle with 5.
The most dangerous injuries for a pedestrian being run into by a passenger car
are head injuries, which may arise when the head of the person collides with the
hood, at an oblique angle from above, down towards the hood. Where on the hood the
person's head hits, depends of course on where at the front part of the vehicle
the collision occurs, the construction of the car at the front, as well as the height
of the person. Investigations of accidents occurred have shown that the head of
a child normally ends up in the schematically marked area 6 shown with dotted lines
in figure 2, while the head of a grown ends up more rearwardly, and usually in the
schematically marked area 7 shown with dotted lines. The hood itself is constructed
so that it is vertically deformed under absorption of a predetermined vertical load,
being chosen less than a value at which serious head injuries may be inflicted on
a person. Then it is of course necessary that there is enough deformation space
under the hood at the areas where there is a high risk that the head of the person
being run into ends up. In most passenger cars with hinges applied at the rear part
of the hood the hinges of the hood are located in the risk zone where the head of
a grown pedestrian may collide.
In figure 3 the different parts of the schematically shown forward
half of the car have been provided with the same reference denotations corresponding
to details in figures 1 and 2.
The hood 3 is at each side suspended by hinges 8. These are fixed
in two rods connected to the hinges, a draw rod 9 and a vertical rod 10. The opposed
ends of the rods 9, 10 in relation to the hinges are fixedly mounted to hard supporting
body beams, which have been denoted with 11 in figure 3. The draw rods 9 are arranged
to receive high horizontal forces A at the hood without the draw rods 9 being deformed.
It is important that the draw rod 9 stops the hood from being displaced through
the windshield 5. Further the hood is shaped to have sufficient deformation space
to underlying hard components and this can be difficult to achieve if a hood, which
is normally bent and arcuated, differently in different places, is not fixed in
the longitudinal direction. This is true for the hinge fixings, which support the
hood at the rear. As evident from the drawing, the hinges are supported in the vertical
direction by the vertical rods 10, and if the hood is permitted to be displaced
in the horizontal direction there is no control whatsoever of the vertical load
at which the vertical rod 10 will be deformed and of the length of the deformation
distance between the hinge and underlying hard body components.
The object of the present invention is as mentioned above, to decrease the risk
of serious head injuries on pedestrians being run into if the head of the person
should end up on or near to the hinge fixings.
The principle of the solution is illustrated in figures 4 and 5. The draw rod 9
and the vertical rod are fixedly connected to a body beam 11. The draw rods 9 should
prevent horizontal displacement of the hood and thereby the hinge 8. The vertical
rod 10 is arranged to become permanently deformed in its longitudinal direction
at absorption of a vertical load of a predetermined size, as shown in figure 5.
Permanent deformation means that the vertical rod is plastically deformed. This
type of deformation occurs during essentially constant load, which is preferred
for reducing the risk of said head injuries. Deformation of the vertical rod shall
occur at a low vertical load so that the force against a head falling down towards
the hinge fixing does not become so high that there is a risk that the person becomes
seriously injured. The size of the predetermined vertical load depends on the available
deformation space, i.e. the length of the vertical rod 10 according to the embodiment
in figures 4 and 5. The larger available length between the hinge fixing before
deformation and the underlying hard body beam, the lesser the value can be chosen
of the predetermined vertical load, at which the vertical rod is deformed. The intention
is to completely brake the deformation movement and absorb the kinetic energy before
the hinge and thereby the person's head hits the hard body beam. Optimal effect
is achieved when the vertical rod is arranged to be uniformly deformed and to absorb
the predetermined vertical load during the whole deformation length, i.e., the softer
and the longer brake length, the less injury will occur to the head of the run-into-pedestrian
when it collides into the hood at or near to the hinges. The predetermined vertical
load must of course also be adapted to other strength requirements, for instance
there should not be any risk for the vertical rod to deform when a person jumps
up and sits on the hood in front of a hinge joint.
With a construction according to the present invention it is realistic
to decrease the risk for serious head injuries of pedestrians being run into at
velocities up to 40 km/h, who after collision bump the head into the hood near or
at the hinge fixings. The available deformation length of the vertical rod should
be in the order of magnitude of at least 50-100 mm, preferably exceeding 70 mm,
and the predetermined vertical load in the order of magnitude 1-5 kN, preferably
about 2 kN.
The vertical rod shall be uniformly deformed and absorb the predetermined
force evenly along its length. This even load absorption may be achieved in a number
of different ways. For example the vertical rod can be provided with embossings
along its length, which embossings are shaped to give the vertical rod a plane deformation
at a certain predetermined force. This can also be achieved by the vertical rod,
having a varying thickness along its length, and/or being provided with cavities
in the inside of the vertical rod or the edges thereof.
An embodiment of a hinge fixing is shown in figure 6. The vertical
rod 10 is straight and elongated, and provided with a longitudinal cavity 12 and
two waist cavities 13. Upon deformation, the vertical rod folds outwards at the
In figure 6 the hood has been marked with 3, a hinted windshield with 5 and the
draw rod with 9. Further the head impact area has been marked with 14, which gives
rise to deformation of the vertical rod. Any determined extension of this area is
of course not available, but depends on the actual case of load at different collisions.
An embodiment of a vertical rod has been described above in the drawing.
This may, however, be shaped in many different ways, curved or angled. As has been
described above, the essential thing is, that the vertical rod absorbs the same
load over of all its deformation length.
For instance, a spring is unsuitable as vertical rod.
The invention is not limited to the embodiment described above, rather,
a number of modifications are possible within the scope of the accompanying claims.