Fluid handling – Line condition change responsive valves – Bi-directional flow valves
Patent
1990-09-18
1991-12-24
Michalsky, Gerald A.
Fluid handling
Line condition change responsive valves
Bi-directional flow valves
1374936, F16K 1718
Patent
active
050743309
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an anti abnormal-pressure/vacuum valve installed in a control valve provided in a hydraulic circuit for driving an actuator employed in construction machines and the like.
DESCRIPTION OF THE PRIOR ART
A conventional control valve installed in a hydraulic circuit for driving an actuator employed in machine has a construction, for example such as that shown in FIG. 1, in which: a spool valve 4 is movably mounted in a valve body 1 of the control valve so as to permit/prevent communication between a pump-side port 2 and an actuator-side port 3 in the valve body 1, whereby pressure oil supplied from a hydraulic pump (not shown) to the pump-side port 2 of the valve body 1 is controlled so as to be appropriately supplied to the actuator (not shown) of the machine through the actuator-side port 3 of the valve body.
In the conventional control valve having the above construction, in order to prevent excessive oil pressures or abnormal pressures from being produced in the hydraulic circuit when the actuator is overloaded, and also in order to prevent a possible vacuum from developing in the actuator due to a deficiency of pressure oil therein when the actuator is moved by an external force, there is provided an anti abnormal-pressure/vacuum valve "A" for permitting/preventing the communication between the actuator-side port 3 and a reservoir-side port 5 in the valve body 1 of the control valve, as shown in FIG. 1.
The anti abnormal-pressure/vacuum valve "A" provided in the conventional control valve has a construction, for example, such as that shown in FIG. 2.
In the construction of the conventional anti abnormal-pressure/vacuum valve "A", as shown in FIG. 2, a sleeve-like valve 11 is slidably mounted in a sleeve-like case 10 in an insertion manner. In a front end portion of the valve 11 are formed: a first port 12; and a second port 13. A spool valve 14 is slidably mounted in the sleeve-like valve 11 in an insertion manner so as to permit/prevent communication between the first port 12 and the second port 13 of the sleeve-like valve 11, while pressed against a valve seat formed in a peripheral portion of the first port 12 of the sleeve-like valve 11 under the influence of a resilient force exerted by a compression spring 15 to prevent the communication between the first port 12 and the second port 13. A pressure-introducing tube 16 is slidably mounted in the spool valve 14 in an insertion manner to permit communication between the actuator-side port 3 of the valve body 1 and a valve pressing chamber 17, so that the sleeve-like valve 11 is pressed against a valve seat 1a under the influence of a pressure of the pressure oil supplied to the valve pressing chamber 17 from the actuator-side port 3 through a central port of the pressure-introducing tube 16. The valve seat 1a is formed in a peripheral portion of the actuator-side port 13 of the valve body 1.
In the conventional anti abnormal-pressure/vacuum valve "A" having the above construction, when the valve "A" is subjected to excessive pressure or abnormal pressure at the actuator-side port 13, the spool valve 14 is moved rightward as viewed in FIG. 2 against the resilient force exerted by the compression spring 15 under the influence of such excessive pressure or abnormal pressure to permit the communication between the first port 12 and the second port 13, so that the pressure oil supplied to the actuator-side port 3 at such excessive pressure of abnormal pressure flows out of the port 3 to the reservoir-side port 5, whereby the abnormal pressure is removed from the valve body 1 of the control valve.
On the other hand, in the conventional anti abnormal-pressure/vacuum valve "A" having the above construction, when the valve "A" is subjected to a possible vacuum at the actuator-side port 13, a pressure in the valve pressing chamber 17 reduces so that the sleeve-like valve 11 is moved rightward as viewed in FIG. 2 under the influence of a rightward force acting on the sleeve-like valve 11. Such rightward f
REFERENCES:
patent: 3112763 (1963-12-01), Tennis et al.
patent: 4016903 (1977-04-01), Akashi et al.
Kabushiki Kaisha Komatsu Seisakusho
Michalsky Gerald A.
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