Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Patent
1998-07-16
1999-07-06
Hepperle, Stephen M.
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
251 50, 251 52, F16K 31122
Patent
active
059186275
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a safety valve that is adapted for use in a hydraulic circuit such as those for supplying a discharge pressure fluid from a hydraulic pump into a hydraulic motor.
BACKGROUND ART
There has been known in the art a hydraulic circuit for supplying a discharge pressure fluid of a hydraulic pump into a hydraulic motor, in which the discharge pressure fluid of the hydraulic pump is supplied via an operating valve into one of a pair of principal circuits, of which a first is connected to a first port of the hydraulic motor and a second is connected to a second port of the hydraulic motor.
In a hydraulic circuit of this type, it is customary to use a safety valve of modulation type that is designed to make a relief of a portion of fluid of pressure elevated in the first and second principal circuits to ensure that the elevated pressure may not exceed a pre-established pressure, so that when the hydraulic motor is either to start or to stop driving, fluid pressure in the first or second principal circuit which is active may slowly be elevated in order to diminish a shock that can then be disadvantageously brought about therein. Such a safety valve as known in the art, that is capable of performing a modulation operation in which fluid pressure may rapidly be elevated up to a modulation start pressure and after then slowly be elevated up to a preset pressure, is shown in FIG. 1 of the drawings attached hereto.
More specifically, the safety valve has a valve seat 2 slidably inserted in a sleeve 1 in which a poppet 3 is also slidably inserted so that a concave conical surface 5 of the poppet 3 may be thrusted by a spring 4 against a convex conical surface 6 of the valve seat 2 to provide a valve interface. A piston 7 is slidably inserted in the poppet 3 to form a chamber 8 which is in fluid communication via a small opening 9 and via an inner bore 10 of the valve seat 2 with a high pressure port 11 whereas a low pressure port 12 is formed in the sleeve 1.
And, the sleeve 1 is formed at an end thereof with a large diameter section 20 whose open end has a plug 21 securely fitted therewith. The valve seat 2 is shaped to provide a stepped peripheral configuration having a small diameter one end portion 22, a large diameter mid portion 23 and an intermediate diameter opposite end portion 24. The small diameter one end portion 22 is inserted in the plug 21 to fit with an inner surface 21a thereof and is then sealed with a sealing material 25, whereas the large diameter mid portion 23 is inserted in the sleeve 1 to fit with the large diameter section 20 thereof and is then sealed with a sealing material 26. And, the intermediate diameter opposite end portion 24 is inserted in the sleeve 1 to fit with its inner surface 1a. Thus, the valve seat 2 is allowed to axially be slid and be displaceable by a distance L. Besides, the large diameter mid portion 23 and the sleeve 1 are shaped to provide an annular space 27 between the large diameter mid portion 23 and a step portion 1b of the sleeve 1. The annular space 27 is opening to the low pressure port 12 via an interstice 28 between the sleeve inner surface 1a and the intermediate opposite end portion 24, which is here designed to form a damper chamber A.
Let it be assumed that the section in which the valve surface 5 and the seating surface 6 are to be in contact with each other has a diameter d1, the piston 7 has a diameter d2, and the small diameter one end portion 22 of the valve seat 2 has a diameter d3.
An explanation is now given below of an operation of the conventional safety valve whose construction has been described above.
Assuming that the high pressure port 11 has a pressure that ranges between P1 and 0, the spring 4 forces the poppet 3 which in turn pushes the valve seat 2 to cause it to move by the distance L1 leftwards in the Figure to contact with the plug 21. Here, it should be noted that the spring load F1 of the spring 4 is set at a value that is lower than a conventional value by L1.times.K where K is a spri
REFERENCES:
patent: 4682531 (1987-07-01), Mayer
patent: 5118076 (1992-06-01), Homes
patent: 5451030 (1995-09-01), Reglebrugge et al.
Bastianelli John
Hepperle Stephen M.
Komatsu Ltd.
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