Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a shock absorber
adapted to provide predetermined shock absorbing characteristics,
even when the piston ls operated at short intervals.
The present invention will be lllustrated by reference
to the accompanying drawings, in which:-
Fig. 1 is a sectional view illustratlny a prior art
shock absorber, in which reference numeral 1 designates a casing
lU containing oil, reference numeral 2 designates a cylinder formed
in the casing 1, reference numeral 3 designates a piston which
reciprocates within the cylinder 2, referencP numeral 4 desig-
nates a small orifice having a predetermined diameter formed in
the piston 3, reference numeral 5 designates a spring causing the
piston 3 to return, reference numeral 6 designates hydraulic oil,
reference numeral 7 designates a cover, reference numerals 8 and
9 designate seal members, reference numeral 10 designates a high
pressure chamber in which a high pressure is produced by the pis-
ton 3 during operation, reference numeral 11 designates a low
pressure chamber and reference numeral 12 designates an air
layer.
Next, the operation of the prior art shock absorber
will be described. Referring to Fig. 1, when the piston 3 is
pushed by an external force toward the left in Fig. 1, the pres-
sure of the hydraulic oil rises within the high pressure chamber
10 and a shock absorbing force is generated against the externalforce. Then, the oil 6 within the high pressure chamber 10 is
forced to flow out at a high flow speed into the low pressure
chamber 11 through the small orifice ~ and the oil 6 within the
low pressure chamber 11 is churned up and mixed wlth air within
the air layer I2. The oil is subsequently stabilized as shown in
Fig. 2. When the external force is removed, the piston 3 is
moved by the spring 5 toward the right in Fig. 1. The oil 6
`: within thé low pressure chamber }1 is forced to flow into the
high~pressure chamber 10 through the small oriflce 4. If the
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piston 3 is returned within a short tlme after the shock absorb-
ing operation, the air mixed in with the oll 6 flows into the
high pressure chamber 10.
Therefore, the prior art shock absorber has problems in
that regular shock absorbing char~ckeristics cannot be obtained
during short interval operatlon because of the air mixing in with
the oil 6.
The present invention has been made to eliminate the
aforesaid problems and provides a shock absorber adapted to pro-
vide regular shock absorbing characteristics.
According to the present invention there is provided a
shock a~sorber comprising a piston disposed in a cyli~der con-
taining liquid, the piston having a common axis with said cylin-
der and dividing the cylinder into a high pressure chamber and alow pressure chamber, the low pressure chamber having an air
layer with a free interface between said air layer and said liq-
uid, said interface lying generally parallel to the axis of said
cylinder, said piston comprising an orifice connecting at a first
end with the high pressure chamber and connecting at a second end
with the low pressure chamber and with an axis at said second end
normal to said interface so that the liquid is forced to flow
from the high pressure chamber into the low pressure chamber
~5 through the orifice with the piston is moved toward the high
pressure chamber, the shock absorber ~urther comprising a shield-
in~ member dlsposed within the low pressure chamber, said shield-
ing member fixed in set apart relation to sald second end and
lying between said second end and said interface, said member
comprising a solid surface normal to the axis of said second end
and spaced apart from said second end so as to oppase the flow
arPa of the orifice, thereby reducing the speed o~ liquid flow
fram the second end of the oriflce. Suitably said plston has a
cylindrical portion extending into the low pressure chamber and
said shielding member is toroidal ln form and coaxial with said
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cylindrical extension.
The shock absorber according to the prPsenk invention
thus includes a shielding member disposed between the orifice
formed in the piston and the air layer ~ormed in the low pressure
chamber.
The shock absorber according to the present invention
is adapted such that the oil flowing out at high speed through
the orifice is reduced in flow speed by means of the shielding
member during the operation of the piston, thereby preventlng the
oil ~rom mixing with the air in the air layer within the low
pressure chamber.
- The present invention will be further illustrated by
way of the accompanying drawings, in which:-
Fig. 1 is a sectional view of the prior art shockabsorber with the piston outward of the cylinder;
Fig. 2 is a s~milar sectional view of the shock
absorber of Fig. 1 with the piston in an inwardly of the cylin-
der; and
Fig. 3 is a sectional view of the shock absorber of one
embodiment according to the present invention.
In the Figùres, the same reference denote the same and
corresponding parts.
The present invention will be readily clear from the
following description in which the preferred embodiment has baen
set forth in detail in con~unction with Fig. 3, wherein reference
numeral 13 designates a shielding member disposed between the
orifice 4 formed~ln the piston 3 and the air layer 12, the other-
parts l and 12 being the same as those set forth ln regard to the
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prior art shock absorber.
In the shock absorber constructed as stated above, the
flow speed of the oil 6 flowiny out of the high pressure chamber
11 at high speed through the orifice ~, is reduced b~ striking
against the shielding member 13, when the piston is operated, so
that the oil 6 flows into the low pressure chamber 11 at low
speed through a gap formed between the piston 3 and khe shielding
member 13. Therefore, the oil 6 within the low pressure chamber
11 is not churned up and mixed with the air in the air layer 12,
even when the plston is returned within a short tlme after the
operation, thereby preventing the air from flowing into the high
pressure chamber 10.
` Thus, accordlng to the present invention, a shielding
member is provided which reduces the flow speed of the oil flow-
ing into the law pressure chamber through the orifice due to the
movement of the piston, thereby resulting in stable performance
even when the piston is operated at short intervals.
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