Motors: expansible chamber type – With motive fluid valve – Pilot valve
Patent
1995-05-22
1997-03-04
Ryznic, John E.
Motors: expansible chamber type
With motive fluid valve
Pilot valve
91464, 91467, 13759612, 13762569, F15B 1104, B66C 1320, E02F 922
Patent
active
056069014
DESCRIPTION:
BRIEF SUMMARY
This application is based upon international application No. PCT/JP93/01781 filed Dec. 8, 1993.
TECHNICAL FIELD
The present invention relates to a hydraulic circuit for turning purposes, that is adapted to supply a pressurized discharge oil of a hydraulic pump to a turning-purpose hydraulic motor for turning the upper vehicle body of a power shovel or the upper turning body off a crane.
BACKGROUND ART
Among the conventional hydraulic circuits for turning a crane, there is known a circuit which, as shown in FIG. 1, is designed to supply a pressurized discharge oil off a hydraulic pump 1 to a turning-purpose hydraulic motor 3 via a directional switching valve 2. The directional switching valve 2 may be a directional switching valve of center-bypassing type in which a spool 6 is fittedly inserted into a spool bore 5 of a valve body 4 as shown in FIG. 2.
In this hydraulic circuit, the spool 6, when lying at a neutral position as shown in FIG. 2, is adapted to unload the pressurized oil from the pump 1 via a center-bypassing passage 7 to a tank 8, while closing between a first and a second actuator port 9 and 10 connected to the turning-purpose hydraulic motor 3 on the one hand and a tank port 11 on the other hand to halt the turning movement of a turning body. When the spool 6 is slidably moved by the operator for switching the directional switching valve 2, the center-bypassing passage 7 is throttled to increase the pump pressure while opening between a turning pump port 12 and the first or second actuator port 9 or 10. If the pump pressure is raised above the drive pressure for turning, the pressurized oil is caused to thrust a check valve (a valve for preventing a reversed flow) 13 open to flow and the return oil from the turning-purpose hydraulic motor 3 flows to the tank 8 after passing between one of the second and the first actuator port 10 and 9, that are opening simultaneously, and the tank port 11. Accordingly, it follows that the turning-purpose hydraulic motor 3 is caused to rotate with a rate of the flow that results by deducing from the pump discharge quantity the flow quantity that is bled off into the tank 8 from the center-bypassing passage 7.
As a matter of course, if the spool 6 is further slidably moved to a full stroke end to completely close the center-bypassing passage 7, the turning-purpose hydraulic motor 3 is rotated by using a full quantity of the pump discharge.
Also, when the hydraulic motor 3 is to be stopped, it is braked by slidably moving the spool 6 in the opposite direction to throttle the opening between the afore-mentioned second or first actuator port 10 or 9 and the tank port 11. The motor 3 is reduced in speed by setting the pressurized oil supplied from the hydraulic pump 1 free into the center-bypassing passage 7. The turning-purpose hydraulic motor 3 is finally stopped by closing between the second or the first actuator port 10 or 9 and the tank port 11.
In this connection, it should be noted that the opening between the afore-mentioned second or first actuator port 10 or 9 and the tank port 11 and the opening of the directional switching valve for the center-bypassing passage 7 vary oppositely to each other.
As in the foregoing, the rate of flow controlled when the turning-purpose hydraulic motor 3 is accelerated is determined depending on how much the quantity of flow from the center-bypassing passage 7 is set free into the tank 8. In other words, when the opening of the center-bypassing passage is larger, the rate of flow into the turning-purpose hydraulic motor 3 is less. And, when the opening of the center-bypassing passage 7 is smaller, the rate of flow into the turning-purpose hydraulic motor 3 is increased.
However, the rate of flow into the turning-purpose hydraulic motor 3 if the pump discharge rate is small is made equal to that in which the quantity set free from the center-bypassing passage 7 is increased if the pump discharge rate is large. Accordingly, it is necessary to further throttle (lessen) the opening of the center-bypassing passage 7 in or
REFERENCES:
patent: 2971536 (1961-02-01), Junck et al.
patent: 3151455 (1964-10-01), Tennis
patent: 3747350 (1973-07-01), West et al.
patent: 3763746 (1973-10-01), Walters
patent: 4066239 (1978-01-01), Hall
patent: 4109561 (1978-08-01), Junck et al.
patent: 4667930 (1987-05-01), Latimer et al.
patent: 4776416 (1988-10-01), Chatterjea et al.
patent: 5212950 (1993-05-01), Shirai et al.
Kabushiki Kaisha Komatsu Seisakusho
Kananen Ronald P.
Ryznic John E.
LandOfFree
Hydraulic circuit for turning purposes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic circuit for turning purposes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic circuit for turning purposes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2138920