Shock absorber for water jet ski

Disclosed is a shock absorber for a water jet ski which comprises a cylinder-and-piston assembly, the cylinder and piston of which are pivotably attached to a water jet ski body and to the handlebar of the water jet ski respectively. The fluid filled in the cylinder is allowed to pass through the orifices of the piston body while the piston moves back and forward in the cylinder in response to the rise and descent of the handlebar. With this arrangement the rider can move up and down the handlebar so freely as to permit him to keep his balance on the water jet ski while running on water. The orifice size is selected to be appropriate for the purpose of preventing uncontrollable quick move of the handlebar which otherwise would be caused by sudden application of strong force to the water jet ski body, thereby preventing the rider from losing his balance on the water jet ski.

FIELD OF THE INVENTION 
The present invention relates to a shock absorber which is suitable for 
absorbing the force which is applied to the handlebar of a water jet ski 
while running on water. 
DESCRIPTION OF THE PRIOR ART 
As is well known, a coiled spring is placed between the body and the 
handlebar of a water jet ski to raise and keep the handlebar in its 
initial raised position, thereby permitting a rider to hold his riding 
posture easily on the water jet ski while running on water. 
The water jet ski runs on water at such a high speed that a relatively 
strong force is liable to be applied to the water ski body. Particularly 
when the water jet ski lands on water after jumping high, a strong force 
will be applied to the water ski body to make the handlebar to descend 
downwards. It is, therefore, necessary to provide means to prevent the 
handlebar from lowering on such occasion. As described above, a coiled 
spring is placed between the body and handlebar of the water jet ski. The 
resilient strength of the coiled spring, however, can be strong enough to 
raise and keep the handlebar in its initial raised position in normal 
condition, but cannot be enough to hold the handlebar in its raised 
position against the strong force which tends to push the handlebar 
downwards. 
The resilient strength of the coiled spring can be increased in the hope of 
raising and holding the handlebar in its raised position at all times. 
This, however, can be no remedy because use of a strong resilient spring 
prevents a rider from moving the handlebar freely up and down for steering 
the water jet ski. Therefore, use cannot be made of a coiled spring whose 
resilient strength is strong enough to resist to the lowering of the 
handlebar when a strong force is applied to the water jet ski. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a water jet ski whose 
handlebar can be moved freely up and down, still guaranteed free of 
uncontrollable lowering of the handlebar due to sudden application of 
strong force to the water ski body. 
To attain this object a shock absorber for a water jet ski, the base end of 
which shock absorber is pivotably attached to the front of said water jet 
ski body, and the other end of which shock absorber is adapted to act on 
the handlebar of said water jet ski, is improved according to the present 
invention in that it comprises a hollow cylinder and a piston rod having a 
piston body which tightly fits in said cylinder to divide the inner space 
of said hollow cylinder in two variable pressure chambers, both of which 
are filled with a fluid, said piston body having orifices, said hollow 
cylinder extending between and being fixed to the vicinity of the pivot 
end of said handlebar and said water jet ski body. 
Two variable pressure chambers communicate with each other through the 
orifices of the piston body. The rider can freely move the handlebar while 
the water jet ski is running on water at normal speed. The speed at which 
the rider can move the handlebar vertically can be determined by the flow 
rate at which the fluid can pass through the orifices per unit time. The 
handlebar can be prevented from descending upon sudden application of 
strong force to the water ski body by appropriately selecting the orifice 
size, and hence the flow rate of the fluid through the orifices of the 
piston body.

Referring to FIG. 1, there is shown, partly broken, a water jet ski 
equipped with a shock absorber according to the present invention. As seen 
from the drawing, handlebar 2 is pivotably attached about its pivot 3 to 
water jet ski body 1. Coiled spring 4 is wound around pivot 3 to apply its 
resilient force against handlebar 2, thereby causing handlebar 2 to be 
spring-biased upwards. 
Pin hole 6 is made in water jet ski body 1 and handlebar 2, and when 
handlebar 2 is pushed down in inoperative position as shown in FIG. 1, pin 
5 is inserted in pin hole 6, thereby keeping handlebar 2 in inoperative 
position. In use pin 5 is removed from pin hole 6, and then handlebar 2 
will be automatically raised by resilient force of coiled spring 4 to 
operative position. 
As seen from the drawing, shock absorber 10 is installed between water jet 
ski body 1 and handlebar 2 according to the present invention. 
As shown in FIG. 2, shock absorber 10 comprises hollow cylinder 11 and 
piston rod 12 having piston body 15 which tightly fits in cylinder 11 to 
divide the inner space of hollow cylinder 11 in two variable pressure 
chambers 13 and 14. Both chambers are filled with fluid. 
Piston body 15 has orifices 16. The fluid may be high-pressure gas, oil or 
oil-contained gas. 
Shock absorber 10 is fixed to handlebar 2 by hinge 18 of piston rod 12, and 
to water jet ski body 1 by hinge 19 of hollow cylinder 11. 
When the water jet ski is in running position as shown in FIG. 3, shock 
absorber 10 has its piston body 15 at an intermediate position in hollow 
cylinder 11 as seen from FIG. 4. As described earlier, piston body 15 has 
through orifices 16 to permit the fluid to be displaced from one of 
pressure chambers 13 and 14 to the other when piston body 15 moves in 
cylinder 11. When the rider moves handle 7 up and down, handlebar 2 will 
be able to move accordingly without resistance. 
Handlebar 2 can be moved smoothly. However, it should be noted that the 
orifice size which controls the flow rate of the fluid to be displaced 
from one to the other pressure chamber, is determined so as to prevent 
piston rod 12 from moving quickly. Assume that water jet ski body 1 is 
raised on water, causing a pull-down force to be applied to handlebar 2 as 
counter action. If the orifice size is determined appropriately, piston 
rod 12 will make a resistance against such pull-down force, thereby 
preventing handlebar 2 from descending. Therefore, rider 20 need not give 
a pull-up to handlebar in an attempt to counter the pull-down force when 
water jet ski body is suddenly raised on water. This favors the steering 
of water jet ski, allowing the rider to keep his posture with ease. 
Contrary to the above, assume that water jet ski body 1 is lowered on 
water, causing a push-up force to be applied to handlebar 2. Then, piston 
rod 12 will make a resistance against such push-up, thereby preventing 
handlebar 2 from rising. 
Referring to FIG. 5, there is shown a water jet ski equipped with a shock 
absorber according to a second embodiment of the present invention. 
In this particular embodiment coiled spring 4 is removed, and only shock 
absorber 10 is used to hold handlebar 2 at a controlled position. Thus, 
the number of parts to make up a water jet ski is reduced, and the weight 
and manufacturing cost are reduced accordingly. 
Referring to FIGS. 6 and 7, there is shown a water jet ski equipped with a 
shock absorber according to a third embodiment of the present invention. 
Shock absorber 10 is fixed to handlebar 2 and jet ski body 1 so as to 
extend to its full length in normal running position as shown in FIG. 6. 
Therefore, shock can be absorbed only when a force is applied to push down 
handlebar 2. This one-way shock absorption makes it easy to determine 
orifice size in piston body 15, and therefore shock absorbers can be 
produced with less difficulty. 
As may be understood from the above, a shock absorber according to the 
present invention uses a cylinder-and-piston assembly the cylinder and 
piston of which are pivotably attached to a water jet ski body and to the 
handlebar of the water jet ski respectively, allowing the fluid to pass 
through orifices of the piston body while the piston moves back and 
forward in the cylinder in response to the rise and descent of the 
handlebar. With this arrangement the rider can move up and down the 
handlebar so freely as to permit him to keep his balance on the water jet 
ski while running on water. The orifice size is selected to be appropriate 
for the purpose of preventing uncontrollable quick move of handlebar, 
which otherwise, would be caused by sudden application of strong force to 
the water jet ski body, thereby preventing the rider from losing his 
balance on the water jet ski.