DE1817822C3 - Main flow control valve, in particular to lower the load for the lifting cylinder, separated from 1813500 - Google Patents

Description

2. Main flow control valve according to claim 1, that 25 increases with lower load or during idle stroke,
characterized in that a further environment is The solution according to the invention consists in that hungsleitung is provided. on the valve piston on the bypass line

3. Main flow control valve according to claim 2, on the related side grooves are arranged through which are marked by - \ et that the load or the load-dependent controlled partial flow of the depending controlled partial flows narh the passage 30 main line from the lifting cylinder ren when lowering the load of the valve piston (37) again with which the flowing pressure medium flow flows off.
Throttle point (34) passing pressure medium flow As a result, on the one hand, the safety requirements are combined. met at high loads, and on the other hand a

4. main flow control valve according to claims 2 rapid lowering with idle strokes and low Laund3, characterized in that the load ab- 35 sten allows. A particular advantage of this Lö-dependent control of the partial flow (s) through solution is the fact that an adaptation to a wide variety of depressions or characteristics changing over the length can be achieved practically without additional axially extending slots or grooves (40) at the same cost.
Cross-section on the surface of the valve piston. A further bens (37) can expediently also take place, whereby it is provided with chambers in the bypass line.

the valve piston receiving bore together - An advantageous embodiment of the main

work. flow control valve is that the load or

5. main flow control valve according to claims 3 dependent controlled partial flows after Passieund4, characterized in that the valves of the valve piston again with that of the throttle piston (37) the opening and closing of the pressure medium flow passing through the area combines the heating lines for the partial flows. the. The load-dependent one takes place with advantage

Control of the partial flow or flows through axially extending slots or grooves are the same or overlap

the length changing cross-section on the upper

50 area of the valve piston, cooperating with chambers in the bore receiving the valve piston. The valve piston is expediently

The invention relates to a main flow control valve, ben the opening and closing of the bypass line

in particular for lowering the load for lifting cylinders, bringing about conditions for the partial flows,

with a valve piston with a variable 55

Flow cross-section, the one of a pump to play with reference to the drawings in more detail

a lifting cylinder or a lifting cylinder to be explained. In the drawings shows

a main line F i g leading to a pressure medium tank. 1 the control valve according to the invention,

controls, which is provided with a throttle point and F i g. 2 a graphic representation of the lowering

on the page 60 opposite the reciprocating piston characteristic.

the throttle point on the one effective area of the valve In F i g. 1 is the process of lowering the load dark piston of the control valve acts while the. The load P acts on the piston 32, and the The effective area of the valve piston via an oil lowering flow Q shown with arrows passes through the hungsleitung with the piston facing throttle point 34, whereby in that of the throttle side the throttle point is in communication. 65 put 34 following line section 35 a ver-for Load lowering processes are set for two reasons reduced pressure, which is based on the in F i g. 1 Frequently a flow control device acts on the effective surface 31 of the valve piston 37 on the right-hand side of the load cylinder, switched on. On the one hand it is desired that the higher pressure from section 33 of the main

cine high lowering speed in the case of a ^L ti « ^P ÄSeiglei.un _gi nFo ™ de _r N", e "

also another

Delivery line, which is located on the side of the throttle cell 34 facing the reciprocating piston 32, acts via the bypass line 38 to the other active surface 36 of the valve piston 37.

Due to the pressure difference on the two active surfaces 31 and 36 of the valve piston 37, a force arises which, with the force of the spring 39, creates a state of equilibrium. The lowering characteristic of such a device known per se is shown by the dashed curve 24 in FIG. 2. At the lowest loads P1 there is initially the influence of the throttle point 34, which is decisive for the lowering speed. During the control process, the characteristic curve of the spring J> 9 leads to a slight increase in the lowering speed as the load F 2 increases. The curve 25 in FIG. Figure 2 illustrates the lowering characteristic achieved according to the invention. Due to the arrangement of the grooves 40 on the valve piston 37, at low loads P1 an additional current flows via the bypass line 38 ao and the branch line formed by the grooves 40. After passing through the valve piston, this additional oil flow is combined with the main pressure medium flow which has passed the throttle point 34. There-

through is, as well as the curve 25 in F i g. 2 shows 35 can be achieved

small _{40 can}

Way what too

is enough.

1 sheet of drawings

Claims (1)

ι 2 Control of the load cylinder via a directional control valve υ, ■ ·. that the oil displaced by the load cannot flow back directly in the claims: 1. Main flow control valve, in particular for the load control process, a predetermined maximum lowering lowering for lifting cylinders, with a valve speed is not exceeded. Besides that Pistons with a variable flow cross-flow control devices become the load cylinder cut, one downstream from a pump to a lifting device as a safety device cylinder or from a lifting cylinder to a pipe break to ensure that even-pressure medium tank leading main line io if a specified maximum lowering speed is controlled, which is provided with a throttle point, speed is not exceeded even at high loads and on the one opposite to the reciprocating piston. Side of the throttle point on the one effective area The use of a flow control valve, which is The valve piston of the control valve acts, depending on the load pressure, an approximately constant trend the other effective surface of the valve piston 15 produces lowering speed is known per se. at However, post-pistons occur via a bypass line with the devices known to the lifting device facing side of the throttle point in parts to the extent that even with the lowest loads The connection is thereby marked or the lowering speed if the loading area is empty e t that on the valve piston (37) is on the other hand very low. leading to undesirable Zeitverluhungsleitung (38) associated side grooves (40) 20 most leads to the empty lifts. are arranged, by means of which a load-dependent ge. In contrast to the present invention controlled partial flow of the task based on the main line, in a simple manner for load (33, 35) from the lifting cylinder (32) when the load is lowered, a lowering characteristic is available. ken flowing pressure medium flow flows off. to make bar at the lowering speed