DE2725917A1 - FIVE-CHAMBER DIRECTIONAL VALVE WITH DIRECT ELECTROMAGNETIC ACTUATION FOR SOFT SWITCHING - Google Patents

Abstract

In order to damp the hydraulic shocks which arise upon reversing the five-chamber directional control valve, the control plunger (7) has milled recesses (6, 19) with control edges (15, 20) on its end collars (23, 24). As a result, spring spaces (9, 18) are always filled with control oil from the return chambers (8, 21) in the end positions of the plunger, and, during a subsequent switching operation, the control plunger (7) must necessarily displace a volume of control oil via restrictions (16, 17). This brings about a reduction of its switching speed and a damping of the reversal shocks. The valve is of simple construction and can therefore be manufactured at a favourable cost. <IMAGE>

Description

Five-chamber directional control valve with direct electromagnetic actuation

for soft reversal The invention relates to a five-chamber directional control valve with direct electromagnetic actuation for soft reversal, whereby the control piston is moved from one switching position to the other by means of magnetic or spring force and at the same time a volume of oil from its front side via one or more fixed or displaced adjustable throttling points on its rear side.

Directional control valves are known under the term control slide and are used to control hydraulic cylinders or hydraulic motors, or

on or off or change the working direction.

The direct operated slide valves available to date have the disadvantage that the control processes run relatively quickly and thus in the unpleasant switching shocks can occur in hydraulic systems. Annoying noise development, Overstressing of the mechanical parts (especially when there are large masses must be moved here), premature wear and tear, irresponsible pressure peaks in the system and lower quality of the products to be produced on the relevant Production machines are side effects of this unfavorable, undamped Reversals.

All these disadvantages have so far been countered with e.g. hydraulics pilot operated slide valves (with switching time setting and beveled control edges) or you built in shock protection plates. Depending on the application, even proportional or servo valves are used to get the start-up characteristics under control. However, these solutions were relatively expensive. You wanted to build cheaper, one contented oneself with the mere chamfering of the control edges. This method was however To a large extent, it is not very effective because of the switching speed of the spool could not or only poorly be controlled.

The invention is based on the task of simplifying the control sequence Means to control and adjustable to delay.

According to the invention, this is achieved in that the control piston has millings with control edges on its end collars, so in the piston end positions the spring chambers are always refilled with oil and the control piston with a subsequent one Circuit must necessarily displace an oil volume via a throttle point.

An exemplary embodiment is described below with reference to the accompanying drawing and its function is described in more detail. The figure shows a four-way two-position control slide 1 in working position, e.g. "forward". Pressure connection 2 is with consumer connection 3, the consumer return 4 is also connected to the tank connection 5. Above the milling 6 on the control piston 7, oil flows from the return chamber 8 into the spring chamber 9. When the control piston 7 is a force through the armature 10 of a pressure-tight If the solenoid acts, the control piston moves to the right. Before the consumer through the control piston 7 and its control edges 11, 12, 13 and 14 is switched from "forwards" to "backwards", the control edge 15 closes the connection between the return chamber 8 and the spring chamber 9. That is in the pen room 9 now has to enter the spring chamber 18 via the throttle points 16 and 17 be displaced. Depending on the throttle cross-section, the control piston 7 is now more or less braked and thus a smooth switchover of the consumer is achieved.

Shortly before the control piston reaches its right end position (working position "Backwards") is reached via the milling 19 and the control edge 20, spring space 18 connected to the return chamber 21 and this is safely filled with oil.

If the force on the armature 10 drops, the working spring 22 switches the Control piston 7 to the left again in the "forward" working position, this is now oil displaced from the spring chamber 18 into the spring chamber 9.

Of course, the subject of the invention can apply to all customary directly operated control spool can be used. Especially on four-way three-position valves with two working positions and neutral position. Likewise, the invention applies to everyone Piston symbols applicable. Also, the invention does not apply to electrically operated ones Valves are limited, but can also be mechanical, pneumatic or hydraulic actuated valves are used.

Claims (2)

patent claims. 7 Five-chamber directional control valve with direct electromagnetic actuation for soft reversal, with the control piston using magnetic or spring force is moved from one switching position to the other and at the same time an oil volume from its front side via one or more fixed or adjustable throttle points displaced onto its rear side, characterized in that the control piston (7) on its two end collars (23, 24) milled portions (6, 19) with control edges (15, 20) has so that the spring chambers (9, 18) always with oil in the piston end positions be refilled and the control piston (7) forcibly with a subsequent shift a volume of oil must displace via a throttle point. 2. Five-chamber directional valve according to claim 1, characterized in that that the spring chambers (9, 18) by means of non-return valves from the return chambers (8, 21) can be refilled from.