Motors: expansible chamber type – With motive fluid valve – Relatively movable serial valves
Patent
1996-09-27
1998-05-19
Michalsky, Gerald A.
Motors: expansible chamber type
With motive fluid valve
Relatively movable serial valves
91451, 91529, 13759618, 1375962, 13762566, 251151, F15B 13042, F15B 1308
Patent
active
057524262
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a pilot pressure operated directional control valve for switching the flows of a pressure fluid by slidably displacing a spool under a pilot pressure, and to an apparatus for controlling an operating cylinder by using such a directional control valve in which a boom cylinder, an arm cylinder or a bucket cylinder of a power shovel or the like operating cylinder is supplied with a pressure fluid so as to control an operating extension and an operating retraction thereof.
BACKGROUND ART
A certain pilot pressure operated directional control valve has hitherto been known as disclosed in Japanese Unexamined Patent Publication No. Hei 3-172602.
Thus, it is known that in such a directional control valve, as shown in FIG. 1 of the accompanying drawings hereof, a housing 1 is formed therein with a spool bore 2 to which a pump port 7, a first and a second actuator port 8 and 9, and a first and a second tank port 10 and 11 are opened. The spool bore 2 has a spool 3 fittingly inserted therein whereas the housing 1 has a pair of spring boxes 4 disposed at its left hand side and right hand side, respectively. The spool 3 is adapted to assume a neutral position when it is energized by a spring 5 provided in one of the spring boxes 4 and is adapted to be slidably displaced either against, or in a cooperation with, a resilient force by the spring 5 to take a first position or a second position by supplying a pilot pressure fluid into one of pressure receiving chambers 6 formed in the left hand side and right hand side spring boxes 4, respectively, to establish and block communication between the pump port 7 and the first or second actuator ports 8 or 9, and communication between the first or second actuator ports 8 or 9 and the first or second tank ports 10 or 11.
This notwithstanding, however, such a pilot pressure operated directional control valve is constructed in such a way that the spring 5, the one pressure receiving chamber 6 and a pilot pressure fluid inlet 12 are formed successively on an axis that is coaxial with the spool 3. Since in addition the pilot pressure fluid inlet 12 must be made to have such a length that a piping joint such as an elbow can be in threaded engagement therewith, the corresponding spring box 4 needs to be proportionally lengthened. As a consequence, a problem arises in that the length of the entire directional control valve is necessarily increased and the area of the site on which it is mounted (i. e. a site area) is so enlarged.
Here, whilst if the pilot pressure fluid inlet is formed on a plane that is orthogonal to the spool longitudinal direction of the spring box 4, the length of the spring box 4 can be shortened, then if a plurality of such housings 1 are stacked one upon another and connected together, a problem is brought about in that a piping joint as mentioned above cannot be connected to the pilot pressure fluid inlet since the interstice between the adjacent spring boxes 4 is necessarily small in size.
Furthermore, in such a pilot pressure operated directional control valve, it may be noted that in order for a pilot pressure fluid to be supplied into the pressure receiving chambers 6, a piping joint assembly such as including an elbow must be threaded into and thereby attached to the pilot pressure fluid inlet 12 of the spring box 4.
For example, as shown in FIG. 2 of the accompanying drawings thereof, the pilot pressure fluid inlet 12 can be a threaded bore into which the threaded portion 14 of a piping joint 13 may be inserted for a mating engagement therewith.
With such a construction adopted, in order for the piping joint 13 to be firmly attached to the said spring box 4 and for a fluid leakage from their threaded engagement connection to be prevented, the threaded connection length between the piping joint 13 and the pilot pressure fluid inlet 12 of the spring box 4 needs to be increased. Thus, the threaded portion of the pilot pressure fluid inlet 12 of the spring box 4 engaged with the piping joint 13 being lengthened, the
REFERENCES:
patent: 4417502 (1983-11-01), Shore
patent: 4570672 (1986-02-01), Wilke
Ikei Kazunori
Taka Keisuke
Komatsu Ltd.
Michalsky Gerald A.
LandOfFree
Pilot pressure operated directional control valve and an operati does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pilot pressure operated directional control valve and an operati, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pilot pressure operated directional control valve and an operati will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1844788