DE19909918A1 - Pilot-operated directional valve - Google Patents

Abstract

Pilot-operated directional valves (10, 58, 60) are proposed which, by their construction, allow the formation of valve units (50) which can also be piloted and which can be designed as seat-controlled pulse valves or as changeover valves in an external or internal design. DOLLAR A The directional valves (10, 58, 60) have seat bodies (18, 20, 68, 70) with valve openings of different sizes. Furthermore, the valve spools (26, 64) are equipped with control pistons (32, 34, 82, 84) with piston surfaces of different sizes, each of which is guided in separate control chambers (38, 40, 96, 100).

Description

State of the art

The invention is based on a pilot-controlled directional valve corresponding to the genus of the two independent claims 1 and 2. One equipped with two such directional valves Valve unit is, for example, from US 5,103,866 already known. In this valve unit are the Locking members independently in a common Housing guided and coaxial or parallel to each other arranged. Furthermore, the locking members are among themselves identically designed and with control pistons at their ends different dimensions. In active connection with the seat bodies on the housing side form the locking members two seat valves each.

In contrast to the object of the invention Poppet valves have valve openings of the same size and that Piston area of one of the control pistons corresponds in its Area of a valve opening. In the different Switch position lies on the control pistons of the closing elements permanent control pressure on, the reversal takes place through Change in the contacting of the different connections. In total, the entire directional valve has seven different ones Pressure chambers. Its casing is therefore elaborate to manufacture and takes up  large construction volume. An extension of this well-known Design for a valve concept that is pressure medium controlled resettable or mechanically resettable pulse valves and switching valves includes and in which the Locking elements can be arranged coaxially or multiaxially, is at most with this construction with considerable Additional effort possible.

Advantages of the invention

In contrast, the precontrollable according to the invention Directional control valve with the characterizing features of claims 1 or 2 the advantage that it is relatively small Construction effort, the formation of a complete valve concept in the above Scope allowed. Different valve variants can be done with simple structural changes realize. The has been particularly advantageous Construction variant of a bistable or pulse-controlled Double seat valve due to its short response and Switching times and its good internal tightness proven. This tightness decreases with increasing system pressure the pressure force acting on the closing element. The proposed directional valve is made up of several identical parts built and thus requires only small parts and Storage costs.

Further advantages or advantageous developments of Invention result from the dependent claims and the Description.

drawing

Embodiments of the invention are in the drawing shown and in the following description explained.  

Figs. 1 shows an inventive pilot-way valve in a so-called external sealing embodiment in longitudinal section; Figs. 2 to 6 show pilot-operated valve units, which are composed of several directional control valves according to Fig. 1, in different design variants.

FIG. 7 shows an example of the exemplary embodiment of a valve unit disclosed in FIG. 2 as a switching symbol.

Description of the embodiments

In Fig. 1 a first embodiment of a pilot-way valve 10 is shown. This has a housing 12 , shown only schematically, in which a continuous slide bore 14 is formed, the inner diameter of which is multiply offset. The latter is closed at its ends by plugs 16 , only one plug 16 being shown as an example in FIG. 1. In the slide bore 14 open transverse to the longitudinal axis thereof extending and designated by the letters P, A and R pressure medium channels a blind hole. The pressure medium channel P, which is assigned to the inlet and carries pressure medium under operating pressure, and the pressure medium channel R, which is assigned to the unpressurized return, lie opposite the pressure medium channel A. The latter is linked to a consumer, not shown.

When viewed in the longitudinal direction of the directional control valve 10 , the pressure medium channels P, A, R are spaced apart from one another, the pressure medium channel A on the consumer side being located between the pressure medium channels P and R serving to supply pressure medium. The opposite arrangement of the pressure medium channels P and R to A is not decisive for the function of the directional valve 10 .

A first seat body 18 is arranged in the wall area of the slide bore 14 lying between the pressure medium channels P and A, and a second seat body 20 is arranged in the section between the pressure medium channels A and R. Both seat bodies 18 and 20 are designed in a ring shape and have collars on their end faces facing away from one another, which bound valve openings 22 , 24 in the seat bodies 18 , 20 . These valve openings 22 and 24 are of different sizes, the larger valve opening 22 being assigned to the first seat body 18 and the smaller valve opening 24 being assigned to the second seat body 20 .

A slide 26 penetrating both valve openings 22 and 24 is guided axially movably in the slide bore 14 . This slide 26 has pistons 27 which are thickened in diameter with first and second sealing disks 28 , 30 fixed thereon and a coupling section 29 with a reduced diameter and connecting the pistons 27 to one another. Control pistons 32 , 34 of different external dimensions are arranged at the ends of the slide 26 . For assembly reasons, the control piston 34 , which is adjacent to the second seat body 20 and has a larger diameter, is mounted on the slide 26 , while the smaller first control piston 32 can be formed in one piece with the slide 26 . Both control pistons 32 and 34 carry sealing rings 36 in circumferential grooves for sealing control chambers 38 , 40 in which the control pistons 32 , 34 are guided.

The smaller control piston 32 is designed to be larger than the valve opening 24 of the smaller seat body 20 , and the large control piston 34 also has a larger area than the valve opening 22 of the large seat body 18 . The area differences result from taking into account the function of the directional control valve 10 described below in connection with the friction and pressure conditions in the directional control valve 10 that prevail under operating conditions.

In the illustrated basic position of the directional control valve 10 , pressure medium under operating pressure flows from the pressure medium channel P through the valve opening 22 to the consumer connected to the pressure medium channel A. A pressure medium connection between the pressure medium channel A and the return R is closed by the sealing disk 30 resting on the second seat body 20 . The area difference between the second valve opening 24 and the first control piston 32 ensures that the slide 26 remains in this switching position without the control piston 34 being subjected to operating pressure.

The directional control valve 10 is reversed into the switching position (not shown) by a brief pressure pulse on the first control piston 32 . As a result, the first sealing disk 28 bears against the collar of the seat body 18 delimiting the first valve opening 22 and interrupts the connection between the pressure medium channel P and the pressure medium channel A. At the same time, the pressure medium channel A becomes through the valve opening 24 of the second seat body 20 with the pressure medium channel R coupled. The pressure force generated on the slide 26 due to the area difference between the first valve opening 22 and the control piston 32 presses the sealing disk 28 against the seat body 18 , this pressure force being dependent on the operating pressure and increasing with increasing operating pressure. In this switching position described, the control chambers 38 , 40 are depressurized.

The reversal into the basic position shown is also carried out by a brief pressure pulse on the control piston 34 . Its piston area is larger than the valve opening 22 of the first seat body 18 , as a result of which the resulting pressure force on the slide 26 enables a reset. Such a directional control valve 10 is referred to as a pulse valve or as a bistable valve.

The control chambers 38 and 40 are acted upon by pressure medium for reversing the directional control valve 10 via control channels arranged in the housing 12 and indicated only in FIG. 1 as dash-dotted lines. These are supplied with pressure medium by a pilot valve not recognizable in FIG. 1, the pilot valve itself being able to be controlled via supply channels branching off from the pressure medium channel P on the inlet side - not shown.

Fig. 2 shows an assembly 44 of a base plate 46, a pilot valve 48 and a valve unit 50. The latter has a block-shaped housing 52 , which is anchored together with the pilot valve 48 on the base plate 46 . This base plate 46 is traversed perpendicular to the plane of the drawing by channels 54 carrying pressure medium, via which the joint supply or disposal of possibly several units 44 arranged side by side can take place. In the exemplary embodiment, the base plate 46 is provided with branch channels 56 which produce pressure medium connections between the connections of the valve unit 50 and the channels 54 . Furthermore, the base plate 46 has a continuous cavity 47 in which an electronic control device 49 is accommodated. This controls the pilot valve 48 electronically.

The valve unit 50 has a 5/2-way function and, for this purpose, accommodates two separate directional valves 58 and 60 in its housing 52 . The directional control valve 58 is constructed identically to the directional control valve 10 according to FIG. 1. In contrast, the coaxial second directional valve 60 has a slide 64 , the piston 66 of which forms a so-called inner-sealing valve with the seat bodies 68 and 70 . In the case of internally sealing valves, the collars of the seat bodies 68 , 70 surrounding the valve openings 72 and 74 , in contrast to the exterior sealing systems according to FIG. 1, are arranged on the mutually facing inner sides of these seat bodies 68 , 70 . Accordingly, the pistons 66 with their sealing disks 78 , 80 are located between the two seat bodies 68 , 70 and not outside of them. In order to achieve a function comparable to the directional control valve 58 (FIG. 10 ) also for the directional control valve 60 , the area ratios of the control pistons 82 and 84 or the seat bodies 68 , 70 were maintained and the assignment of the control pistons 82 , 84 to the seat bodies 68 , 70 was changed. Accordingly, the control piston 82 with the smaller diameter is now adjacent to the seat body 68 with the small valve opening 72 , while correspondingly the control piston 84 with the large valve opening 74 is assigned to the seat body 70 . For manufacturing reasons, both control pistons 82 and 84 are made in several parts with the slide 64 . Different from the directional control valve 58 (FIG. 10 ) is also that the connection from the inlet-side pressure medium channel P to the second consumer-side pressure medium channel B is controlled by the seat body 68 with the smaller valve opening 72 , while in the pressure medium connection between the pressure medium channels B and R there are correspondingly reversed conditions .

The combination of an outer-sealing directional valve 58 with an inner-sealing directional valve 60 arranged flush with it results in a particularly inexpensive design of the housing 52 with a single, continuous slide bore 53 . The arrangement of the control channels in this housing 52 is also relatively easy to implement. In this regard, reference is made to the description of FIG. 3.

According to FIG. 3, a plurality of control channels 90 are independent of the triggering a-e provided in the housing 52. The control channel 90 a establishes a pressure medium connection between the control chamber 96 , in which in the exemplary embodiment the two small actuating pistons 32 , 82 are arranged together and the control channel 90 b, which leads to the pilot valve 48 . The part of the pressure medium channel 90 a leading to the outside of the valve unit 50 is only present for production-related reasons and has no pressure medium-carrying function. For these reasons, it is closed to the outside, for example by a plug (not shown). Running parallel to the control channel 90 b, a further control channel 90 c connects the pilot valve 48 to a branch of the pressure medium channel P on the inlet side, which opens into the slide bore 53 of the directional control valve 58 , 60 . The pilot valve 48 is supplied with pressure medium via this control channel 90 c. For the return of pressure medium from the pilot valve 48 , a control channel 90 d is provided which, starting from the pilot valve 48, leads to the return-side pressure medium channel of the directional valve 60 denoted by R. The control channels 90 b-d run essentially parallel to the slide bore 53 .

Another control channel 90 e is located on the side of the slide bore 53 opposite the control channels 90 a-d and connects the two external control chambers 40 and 100 of the directional control valves 58 and 60 to one another. In addition, this control channel 90 e also leads to the pilot valve 48 .

The valve unit 50 shown in FIG. 3 acts against the pulse valve according to FIG. 2 as a changeover valve with pressure medium reset. For this purpose, the control chamber 96 common to the two directional control valves 58 and 60 is permanently pressurized with operating pressure via the control channels 90 a and 90 b. The pressure force thereby acting on the control pistons 32 and 82 brings the two directional control valves 58 , 60 into the basic position shown. For reversing the valve unit 50 , the external control chambers 40 and 100 of the two directional control valves 58 , 60 are also acted upon by operating pressure. This is done by the pilot valve 48 via the control channel 90 e. The pressure force caused by the control pistons 34 and 84 of the directional control valves 58 and 60 is greater than the counterforce exerted by the smaller diameter control pistons 32 , 82 due to the differently sized pressurized surfaces. In the design as a changeover valve, the sealing rings 36 provided on these actuating pistons 32 and 82 can be dispensed with without replacement. As a result, pressure can also build up in the control chamber 96 via the guide gaps of these actuating pistons 32 and 82 . The control channels 90 a or 90 b are not required in this case.

The resetting takes place under pressure medium control, in that the external control chambers 40 , 100 are relieved of pressure via the control channels 90 d and 90 e to the pressure medium channel R on the return side. As a result, the control chamber 96 , which is still under operating pressure, together with the small control pistons 32 , 82 can reset the directional control valves 58 and 60 into the basic position.

In contrast to the bistable pulse valve of the exemplary embodiment according to FIG. 2, the valve unit 50 acts as a pure changeover valve or monostable valve, in which operating pressure is permanently present in at least one of the control chambers 40 , 96 , 100 .

As shown in FIG. 4, the valve unit 50 can also be designed as a changeover valve with mechanical reset. In contrast to FIG. 3, the control chamber 96 , which is common to the two directional control valves 58 and 60 , is not pressurized with pressure medium. The control channels 90 a and 90 b are closed, for example by pressing in a sealing plug. In addition, the control chamber 96 is vented by means of a connection to the pressure medium channel R or to the environment. A compression spring 102 is clamped between the two control pistons 32 and 82 . This presses the two sliders 26 and 64 of the directional control valves 58 , 60 into the basic position shown and is dimensioned such that the pressure forces generated by the control pistons 34 , 84 when the control chambers 40 , 100 are pressurized are sufficient to overcome their pretension.

FIG. 5 shows a construction variant of a valve unit 50 , in which the two directional valves 58 and 60 are not arranged coaxially, but in parallel to one another in the housing 52 . The longitudinal axes of the directional control valves 58 , 60 run perpendicular to the contact surface of the valve unit 50 on the base plate 46 . The two directional valves 58 , 60 are, apart from a two-part design of the slide bore 53 a and 53 b in the housing 52 , identical to those of the previous embodiments. The slide bores 53 a and 53 b are continuous transverse bores in the housing 52 , which are closed at one end by the base plate 46 and at the opposite second end by plugs 104 .

The pressure medium channels P and R run at right angles to the slide bores 53 a, b in the direction of the pilot valve 48 . They connect the slide bores 53 a and 53 b with each other and end in the manner of a blind hole in the slide bore 53 a. The same applies to the control channels 90 a and 90 e leading to the control chambers 96 a, b, 40 and 100. The pressure medium channels A and B are also aligned perpendicular to the slide bores 53 a, b, but, in contrast to the pressure medium channels P and R, are not coupled to one another, but instead run to opposite outer sides of the housing 52 , where they are closed in a pressure-tight manner by pressed-in balls 106 . Longitudinal channels 108 aligned parallel to the slide bores 53 a, b establish a connection of the pressure medium channels A, B to circumferential connections 110 . These connections 110 can alternatively be provided on the base plate 46 or on the housing 52 .

With this construction variant, a particularly compact construction of a valve unit 50 can be realized, the housing 52 of which is also relatively easy to manufacture due to the rectangular ducting.

In addition, FIG. 6 shows a valve unit 50 coupled to a pilot valve 48, likewise with a parallel arrangement of the slide bores 53 a, b in two parts. In contrast to the exemplary embodiment according to FIG. 5, both slide bores 53 a, b here run in the longitudinal and not in the transverse direction to the housing 52 . The pressure medium connections A and B can thereby advantageously be arranged on the end face of the valve unit 50 facing away from the pilot valve 48 . The different control channels, which are only indicated schematically in FIG. 6 by means of dashed lines, are also guided in the longitudinal or transverse direction to the housing 52 in this variant. In order to avoid repetitions with regard to their function, reference is made to the previous explanations.

The illustrated exemplary embodiments according to FIGS. 2 to 6 disclose a wide range of different design variants for valve units 50 with a 5/2-way valve function, which are essentially constructed from two types of directional valves 58 , 60 on which the invention is based. All disclosed valve units 50 have a large number of identical parts and can be at least partially converted into one another by simple structural interventions. The construction principle of directional control valves 10 , 58 , 60 on which the invention is based can accordingly be expanded to a modular valve system with which a wide variety of customer requirements can be implemented without any significant technical outlay.

Fig. 7 shows the circuit symbol for a valve unit 50, in the embodiment of Embodiment 2. According to this circuit symbol of the change-over of the valve unit 50 into its two switching positions by means of electro-pneumatically operated pilot valves 48th The valve unit 50 has a total of five connections designated P, R, A and B, which are numbered from 1 to 5 for the sake of simplicity. Port 1 or P is connected to a pressure generator (not shown ) , port 2 to consumer A, ports 3 and 5 with a return R and port 4 to second consumer B. In the first switching position, ports 1 and 2 or 4 and 5 connected to each other, in the second switching position, connection 1 is connected to connection 4 and connection 2 to connection 3 . Port 3 is locked in switch position 1 and port 5 in switch position 2 .

Of course, changes or additions to the described embodiment possible without Deviate basic ideas of the invention.

Claims (10)

1. Pilot-operated directional valve ( 10 , 58 , 60 ) with a housing ( 12 , 52 ) in which to control pressure medium connections between a pressure medium channel (P) assigned to the inlet, at least one pressure medium channel (R) assigned to the return and at least one , The pressure medium channel (A, B) assigned to the consumer is displaceably guided with a closing element ( 26 , 64 ) which cooperates with seat bodies ( 18 , 20 , 68 , 70 ) and which is used to reverse the directional control valve ( 10 , 58 , 60 ) from the basic position the switching position is equipped with two opposing control pistons ( 32 , 34 , 82 , 84 ) of differently sized piston surfaces, characterized in that a control chamber ( 38 , 40 , 96 , 100 ) is assigned to each control piston ( 32 , 34 , 82 , 84 ) that the seat body ( 18 , 20 and 68 , 70 ) have differently sized valve openings ( 22 , 24 , 72 , 74 ) and that to form an external sealing system in which the facing away from each other l End faces of the seat body ( 18 , 20 ) cooperate with the closing member ( 26 ), the seat body ( 18 , 20 ), which controls a pressure medium connection between the pressure medium channels (P) and (A), has the larger valve opening ( 22 ) and is adjacent to the Control piston ( 32 ) with the smaller piston area. 2. Pilot-operated directional valve ( 10 , 58 , 60 ) with a housing ( 12 , 52 ) in which to control pressure medium connections between a pressure medium channel (P) assigned to the inlet, at least one pressure medium channel (R) assigned to the return and at least one to the consumer Associated pressure medium channel (A, B) a closing member ( 26 , 64 ) cooperating with seat bodies ( 18 , 20 , 68 , 70 ) is displaceably guided, which for reversing the directional control valve ( 10 , 58 , 60 ) from its basic position to the switching position or conversely, it is equipped with two opposing control pistons ( 32 , 34 , 82 , 84 ) of differently sized piston surfaces, characterized in that a control chamber ( 38 , 40 , 96 , 100 ) is assigned to each control piston ( 32 , 34 , 82 , 84 ) that the two seat bodies ( 18 , 20 and 68 , 70 ) have differently sized valve openings ( 22 , 24 , 72 , 74 ) and that to form an internal sealing system in which the one other facing end faces of the seat body ( 68 , 70 ) cooperate with the closing member ( 64 ), the seat body ( 68 ), which controls a pressure medium connection between the pressure medium channels (P) and (B), controls the smaller valve opening ( 72 ) and is adjacent to the control piston ( 82 ) with the smaller piston area. 3. Pilot-controllable valve unit ( 50 ) with a housing ( 52 ) in which at least two pilot-controllable directional valves ( 10 , 58 , 60 ) according to one of claims 1 and / or 2 with the aid of their closing members ( 26 , 64 ) pressure medium connections between pressure medium channels (P, R, A, B) control. 4. Pre-controllable valve unit according to claim 3, characterized in that the closing members ( 26 , 64 ) are arranged in alignment in a common slide bore ( 53 ). 5. Pilot-controllable valve unit according to claim 3, characterized in that the closing members ( 26 , 64 ) are arranged parallel to one another in two slide bores ( 53 a, 53 b). 6. Pilot-controllable valve unit according to one of claims 3 to 5, characterized in that in the common housing ( 52 ) control channels ( 90 a, 90 b) are provided which have a pressure medium connection between the pilot valve ( 48 ) and the smaller control piston ( 32 , 82 ) receiving control chamber ( 96 ) create that further control channels ( 90 c) connect the inlet pressure medium channel (P) to the pilot valve ( 48 ) and that control channels ( 90 e) the pilot valve ( 48 ) to the control chambers ( 40 , 100 ) Couple the larger control piston ( 32 , 34 ). 7. Pilot controllable valve unit according to claim 6, characterized in that the valve unit ( 50 ) is designed as a pulse valve by the pilot valve ( 48 ), the control chamber ( 96 ) or the control chambers ( 40 , 100 ) via the control channels ( 90 b or 90 e) alternately acted upon by pressure pulses. 8. Pilot-controllable valve unit according to claim 6, characterized in that the valve unit ( 50 ) is designed as a switchable valve resettable by the pressure medium by the pilot valve ( 48 ) the control chamber ( 96 ) permanently and in the case of switchover the control chambers ( 40 , 100 ) at times charged with control pressure. 9. Pre-controllable valve unit according to claim 6, characterized in that the valve unit ( 50 ) is designed as a mechanically resettable changeover valve in that the control chamber ( 96 ) is relieved of pressure and receives a compression spring ( 102 ) which is located on the two smaller control pistons ( 32 , 82 ) is supported and its pressure force counteracts the pressure forces generated by the control chambers ( 40 , 100 ). 10. Pre-controllable valve unit according to one of claims 3 to 9, characterized in that the valve unit ( 50 ) controls a double-acting, pneumatic consumer.