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Abstract

In a directional control valve, comprising a valve housing (21) in which a slide receptacle (22) is formed, in which a valve slide (24) equipped with a slide body is arranged, which can be switched axially between two main switching positions, wherein the valve slide (24) can be switched from at least one of the two main switching positions by an energy-saving switching operation into an energy-saving switching position deviating from the main switching positions, wherein the valve slide (24) has two partial slides (38a, 38b) arranged axially one after the other in the slide receptacle (22), which are prestressed by spring means (40) in an axially separated relative position predetermined by stop means (50) of the valve slide (24) and which are axially movable both uniformly and relative to one another in the slide receptacle (22),a safety relief device (54) equipped with at least one relief member (55) is assigned to the valve slide (24), such that the relief member (55) can be moved in the energy-saving switching position into an open position allowing fluid flow from the separated working channel into the feed channel.

Description

[0001] The invention relates to a directional control valve with a valve housing in which a spool receptacle extending axially through between two end walls is formed, in which a valve spool equipped with a spool body is arranged, which is axially switchable between two main switching positions, in which it alternately connects one working channel to a feed channel opening into the spool receptacle and simultaneously the other working channel to a relief channel opening into the spool receptacle fluidically, wherein the valve spool has at least one drive section.which can be acted upon by a driving force that drives the valve spool to switch its position, and wherein the valve spool can be switched from at least one of the two main switching positions by an energy-saving switching operation into an energy-saving switching operation that differs from the main switching positions, in which it separates the other working channel from the feed channel while maintaining the fluid connection between one working channel and a relief channel that is open in the main switching operation existing before the energy-saving switching operation, wherein the valve spool has two partial spools arranged axially one after the other in the spool receptacle, which are pre-tensioned by spring means in an axially separated relative position defined by stop means of the valve spool and which are axially movable both uniformly and relative to each other in the spool receptacle,in the energy-saving position they assume axial relative positions that differ from those present in the main switching process.

[0002] A directional control valve in the form of a multi-way valve of the type mentioned above is known, for example, from DE 10 2016 205 722 B3. The multi-way valve described therein has two axially successive partial slides mounted in a slide holder, which are connected to each other via a coupling element, wherein both one partial slide and the other partial slide are movable relative to the coupling element, so that subordinate associated energy-saving switching positions can be switched from each of the two main switching positions, wherein the stop means between the partial slide and the coupling element are effective in order to assume the respective energy-saving switching position, so that an exact position of the partial slides in the respective energy-saving switching position is possible.

[0003] Furthermore, a multi-way valve of the aforementioned type is known from JP 2000-130616 A, which has a valve spool that can be switched between two main switching positions in which two working channels can be alternately connected to a feed channel and a relief channel. In addition, two energy-saving switching positions can also be specified in which one working channel is connected to a relief channel, while at the same time the other working channel is not connected to either a feed channel or a relief channel.

[0004] DE 10 2011 010 566 A1 discloses a multi-way valve having an axially split valve spool that can be positioned in different switching positions, in which the two valve spool parts can assume different relative positions. In this way, it is possible to connect the two working channels alternately to a feed channel and a relief channel, as well as to disconnect each working channel from both the relief channel and the feed channel while simultaneously connecting the other working channel to a relief channel.

[0005] The object of the invention is to create a directional control valve with which a connected actuator can be operated in an energy-saving, dynamic manner and with increased safety compared to conventional directional control valves.

[0006] This problem is solved by a directional control valve having the features of independent claim 1. Further developments of the invention are described in the dependent claims.

[0007] The directional control valve according to the invention is characterized in that a safety relief device equipped with at least one relief element is assigned to the valve spool, such that the relief element can be moved in the energy-saving switching position into an open position that allows fluid flow from the separated working channel into the feed channel.

[0008] The directional control valve according to the invention, which is expediently designed as a multi-way valve, offers the advantageous possibility of energy-saving operation of a fluid-actuated drive while ensuring high dynamic movement. The valve spool of the directional control valve can be alternately positioned in two energy-saving switching positions. In one energy-saving switching position, one working channel is connected to the supply channel and the other working channel to a relief channel, while in the other switching position, the channel connection is reversed. This allows the two working channels to be alternately supplied with compressed air or depressurized to operate a connected fluid-actuated drive, which has a piston that can be moved between two stroke end positions due to the pressure difference between the two working channels.The integrated energy-saving measures of the multi-way valve allow the valve spool to be switched to at least one energy-saving switching position using a switching process known as an energy-saving switching operation. In this position, the working channel, which was previously connected to a relief channel, remains connected to this relief channel and consequently to a pressure sink. However, the working channel, previously connected to the feed channel, is disconnected from the feed channel. From this switching state onward, the piston of a connected actuator is moved to its end position solely based on the fluid volume already supplied. This results in a relatively low pressure level in the working chamber at the end of the stroke, which is now separated from the feed channel and any relief channel. This leads to a correspondingly low filling level and therefore reduced air consumption.The operating time for moving the piston between the two stroke end positions is nevertheless relatively short, because at the beginning of the stroke the connected feed channel supplies full fluid pressure, thus accelerating the actuator piston significantly at first. Since the energy-saving function is integrated into the valve spool, the directional control valve has a relatively compact design and can be controlled relatively easily to trigger the energy-saving function.

[0009] The valve slide is divided and holds two sub-slides arranged axially sequentially in the slide housing. These sub-slides are axially movable both uniformly and relative to each other within the housing. Due to their relative axial mobility, these two sub-slides assume a different axial relative position to each other in the energy-saving switching position than in any main switching position. The multi-part valve slide also incorporates spring elements that constantly bias the two sub-slides towards an axially separated relative position. This axially separated relative position is defined by integrated stop elements of the valve slide. The stop elements thus limit the axial movement of the two sub-slides.

[0010] The directional control valve also features a safety function with a safety relief device. For the safety of a system equipped with a directional control valve, particularly a multi-way valve, which also includes a fluid consumer, it is sometimes necessary to completely relieve the system, especially by venting it. In this case, the feed channel is disconnected from the pressure source and, like the relief channels, connected to the atmosphere. This can be done, for example, by means of an upstream relief valve. In the invention, however, the safety relief device with the relief element is assigned to the valve spool, i.e., integrated into the directional control valve, and therefore does not constitute an additional component in the sense of an attached relief valve.The directional control valve according to the invention thus combines energy-saving measures with safety measures, which means that this valve can be used in an energy-saving and therefore cost-effective manner even in systems with high safety requirements.

[0011] In a further development of the invention, the safety relief device has at least one check valve which has a check valve element that is movable depending on the pressure difference between the working channel and the feed channel relative to the slide body of the valve slide.

[0012] In a particularly preferred manner, the two partial slides each have a check valve, each of which has a check valve element movable relative to the associated partial slide body.

[0013] In a particularly preferred manner, the check valve element is designed as a component of a sealing ring or sealing ring which is part of a sealing structure that participates in the switching movement of the valve slide.

[0014] In a particularly preferred embodiment, the sealing ring sits in an annular sealing ring receptacle of a control section of the associated valve body and, in the energy-saving switching position, is movable between a basic position that seals the passage between the working channel and the feed channel, and a release position in which at least part of the sealing ring rests against a contact surface of the valve body equipped with a control edge. The control edge assists the restart, i.e., the transfer of the sealing ring from the release position to the sealing basic position. This ensures a defined restart.

[0015] In a particularly preferred manner, the sealing ring consists at least partially of rubber-elastic material, wherein the movement between the shut-off position and the release position takes place by material deformation of the sealing ring.

[0016] In a further development of the invention, the valve spool can be switched from either of its two main switching positions to an energy-saving switching position that differs from the main switching position by means of an energy-saving switching process, with the two energy-saving switching positions being distinct from each other. This allows a piston of a connected fluid-actuated actuator to be moved in an energy-saving manner in both directions of movement. If, due to special circumstances, an energy-saving function is desired or advantageous only in one direction of movement of the piston of the fluid-actuated actuator, the directional control valve can alternatively be designed such that an energy-saving switching position can be predefined from only one of the two main switching positions.

[0017] The valve element is equipped with one or two actuator sections that can be actuated with a drive force to change the switching positions of the valve element. At least one such actuator section preferably includes a drive surface that delimits a longitudinal section of the spool receptacle, referred to as the drive chamber. This drive chamber can be controlled and actuated with a drive pressure medium to generate the drive force. The drive pressure medium is preferably compressed air. The controlled application of compressed air is preferably achieved by means of an electrically actuated pilot valve of the directional control valve. The actuator section comprising the drive surface is preferably formed by a section of the directional control valve designed as a drive piston.

[0018] Switching between a main switching position and an energy-saving switching position can be achieved in particular by one of the partial slides maintaining its relative position with respect to the valve housing, while only the other partial slide shifts with respect to the stationary partial slide and the valve housing.

[0019] Preferably, each partial slide is able to control the fluid connection between the feed channel and one of the two working channels, as well as one of the two relief channels, depending on the switching position of the valve slide. It is therefore possible that each partial slide is functionally assigned to one of the two working channels, which, depending on its relative position with respect to the valve body, it fluidically connects to either the feed channel or one of the relief channels, while simultaneously isolating it from the other channel.

[0020] In a further development of the invention, the spring elements are formed by at least one air spring and / or at least one mechanical spring. Advantageously, a mechanical spring is provided which ensures that, when the pressure is removed to implement an energy-saving switching position from the main switching position, this energy-saving switching position is reached, defined by the spring force of the mechanical spring. In a particularly preferred embodiment, it is only necessary to deactivate the pilot stage, which serves to pressurize the valve spool for its movement from one main switching position to the other. This pressure release already triggers the restoring effect by the spring force of the mechanical spring.

[0021] In a particularly preferred manner, the two partial sliders assume the axially separated relative position in every energy-saving switching position of the valve slide.

[0022] Advantageously, the valve spool can be moved into one of its main switching positions by applying force to at least one of its drive sections, whereby the two sub-spools can simultaneously be moved into the axially separated relative position mentioned above, overcoming the restoring force of the spring elements. The subsequent switch from the main switching position to an energy-saving switching position can then be achieved very simply by removing the drive force. After the drive force is removed, the valve spool switches into the energy-saving switching position, so that the two sub-spools are moved into the axially separated relative position due to the restoring force of the spring elements.

[0023] In a further development of the invention, the two partial sliders assume the axially relative position to each other in every main switching position.

[0024] In a further development of the invention, at least one of the partial slides, preferably only one of the two partial slides, has a spring receiving space formed in its partial slide body, extending in the axial direction of the partial slide body, in which spring means in the form of a mechanical spring, in particular a compression spring, are received.

[0025] In a further development of the invention, the two partial slides are coupled to each other via a coupling element, in particular a pin-like coupling element, such that the coupling element is attached on the one hand to the body of one of the partial slides and on the other hand is coupled to the other partial slide in a relatively movable manner, allowing the partial slides to move apart and towards each other in a relative position.

[0026] In a particularly preferred embodiment, the coupling element comprises a coupling head forming the stop means, which is received in a cavity, in particular a spring receptacle, of the partial slide body of the other partial slide, wherein the coupling head is movable into a stop position that defines the separated relative position of the two partial slides. The coupling element can, for example, be designed as a type of coupling pin or coupling bolt, with a bolt head having a larger diameter than the rest of the bolt, which is expediently received in the spring receptacle of one partial slide, and a bolt shank that is attached to the other partial slide body, for example by means of a screw connection, and is screwed into a threaded receptacle formed on the other partial slide body.

[0027] In a particularly preferred configuration, the mechanical spring is supported on one side by a support member and on the other side by the coupling head. The support member is advantageously located at the end face of the spring receiving chamber, while the coupling head of the coupling element is positioned at the other end of the spring receiving chamber, so that the spring is clamped between the coupling head and the support member.

[0028] A preferred embodiment of the invention is shown in the drawing and is explained in more detail below. The drawing shows: Fig. 1 a perspective view of a preferred embodiment of the directional control valve according to the invention, Fig. 2 a front view of the directional control valve of Fig. 1 without control stages, Fig. 3 a longitudinal section through the directional control valve of Fig. 2, where the valve slide is shown when it assumes a first main switching position, Fig. 4. Turn off the multi-way valve Fig. 3 in longitudinal section, showing the valve slide when it assumes a first energy-saving switching position following the first main switching position, Fig. 5 the multi-way valve off Fig. 2 in longitudinal section, showing the valve slide in a second main position, Fig. 6. Turn off the multi-way valve Fig. 2 in longitudinal section, showing the valve slide when it assumes a second energy switching position following the second main switching position, Fig. 7 a front view of a modified version of the valve made of Fig. 2, Fig. 8 the directional control valve off Fig. 7 in longitudinal section, showing the valve slide in the first main switching position in inactivated safety relief device and Fig. 9 the directional control valve off Fig. 7 and Fig. 8 in longitudinal section, with the safety relief device activated.

[0029] The Fig. Figures 1 to 9 show a preferred embodiment of a directional control valve 12 designed as part of a fluid power device 11. As shown in particular in the Fig. 3 and Fig. As shown in Figure 5, the fluid power device 11 comprises a fluid-operated actuator 13 connected to the directional control valve 12, which in the example shown is designed as a multi-way valve.

[0030] If the description refers to a fluid or pressure medium, this primarily means compressed air, although other pressure fluids, such as hydraulic pressure media, are also possible.

[0031] The fluid-actuated drive, which is, for example, a linear drive or a rotary drive, has a drive housing 14 and a drive unit 15 movable relative to the drive housing 14. The drive unit 15 has a piston 16 that separates two working chambers 17, 18 from each other within the drive housing 14. By coordinating the fluid action on the two working chambers 17, 18, the piston 16, and thus the entire drive unit 15, can be moved relative to the drive housing 14 between a first stroke end position and a second stroke end position. This allows, for example, a machine part coupled to the drive unit 15 to be displaced by pressure. The stroke movement from the first stroke end position to the second stroke end position is referred to as the first stroke movement 19, and the opposite stroke movement as the second stroke movement 20.

[0032] The directional control valve 12 has a valve housing 21 in which an elongated space is formed, which can be referred to as the spool receptacle 22. The spool receptacle 22 has a longitudinal axis 23 and accommodates an elongated valve spool 24, which is axially displaceable within the spool receptacle 22 relative to the valve housing 21, i.e., in the axial direction of the longitudinal axis 23. In this way, the valve spool 24 can be positioned in different switching positions, which are a Fig. 3 illustrated first main switching positions, one in Fig. 4 shown first energy-saving switch position, one in Fig. 5 shown second main switching position and one in Fig. The second energy-saving switch position shown in section 6 is being discussed.

[0033] The valve spool 24 has two axially oppositely oriented first and second drive surfaces 25a, 25b, each of which can be actuated with a drive pressure medium in order to position the valve spool 24 in the different switching positions. Each of the two drive surfaces 25a, 25b is exemplified on one of two drive sections 26a, 26b of the valve spool 24, which is preferably designed as a drive piston.

[0034] For controlled fluid supply to the two drive surfaces 25a, 25b, the directional control valve 12 preferably has an electrically actuated pilot valve assembly 27, which is expediently designed in the form of two pilot valve units 28a, 28b, each of which is provided for controlled pressure supply to one of the two drive surfaces 25a, 25b. The pilot valve assembly 27 is, for example, a solenoid valve assembly or a piezoelectric valve assembly.

[0035] The slide valve receptacle 22 is bounded at its opposite end faces by a first end wall 29a and an end wall 29b. The slide valve receptacle 22 extends continuously between the two end walls 29a, 29b, which are, in particular, components of the valve housing 21.

[0036] The two actuator sections 26a, 26b are preferably located at the two axially opposite end regions of the valve spool 24. There, each actuator section 26a, 26b, together with the opposite end wall 29a, 29b, defines a first and second actuator chamber 30a, 30b, respectively, into which a pilot channel (not shown) opens. This pilot channel is connected to one of the two pilot valve units and allows the respective actuator chamber 30a, 30b to be pressurized with an actuator pressure medium or, alternatively, pressure-relieved. Each pilot valve unit 28a, 28b is expediently designed as a 3 / 2-way valve capable of connecting the associated actuator chamber 30a, 30b either to a pressure source supplying the actuator pressure medium or to a pressure sink, in particular the atmosphere.The pressure source is in particular the same pressure source P that supplies the pressure medium, which is controlled by the valve slide 24 and supplied to the fluid-actuated drive 13.

[0037] The valve housing 21 is permeated by several valve channels 31 that communicate with the valve receptacle 22. Each of these valve channels 31 has an outer channel opening located on the outer surface of the valve housing 21 and an inner channel opening that opens peripherally into the valve receptacle 22. The inner channel openings of the valve channels 31 are arranged axially apart from one another. In this way, the individual valve channels 31 communicate with valve receptacle longitudinal sections 32 that are arranged axially successively in the valve receptacle 22.

[0038] The valve spool 24 has an elongated control section 33 extending between the two drive sections 26a, 26b. This control section is stepped along its length and consequently has alternating longitudinal sections of larger and smaller cross-sections. The valve spool 24 also carries a sealing structure 34 comprising several sealing rings 35. The sealing rings 35 are arranged on the control section, specifically on the longitudinal sections with the larger cross-section, and are inserted into an annular groove 36 that receives the respective sealing ring 35.Depending on the position of the valve spool 34, the longitudinal sections of the control section equipped with the sealing rings 35 then seal against assigned sections of the wall surrounding the spool receptacle 22, thereby blocking fluid connections, or alternatively, these longitudinal sections of the control section are assigned to areas of the spool receptacle with a larger diameter, thereby opening fluid connections.

[0039] One of the valve channels 31 is a feed channel 31a, which, during operation of the directional control valve 12, is connected via its outer channel opening to a pressure source P supplying the pressure medium to be controlled. In addition to the feed channel 31a, a first and a second working channel 31b, 31c are provided, which expediently open on the same side of the valve housing 21 where the feed channel 31a opens. However, it would also be conceivable for the two working channels 31b, 31c to open on a second housing side opposite the first housing side. The outer channel openings of the two working channels 31b, 31c define a first working port A1, connected to the first working chamber 17 for operating the fluid power unit 11, and a second working port A2, connected to the second working chamber 18 of the actuator 13.

[0040] Furthermore, two relief channels 26d, 26e are provided, which are expediently formed to the left and right of the two working channels 26b, 26c. During operation, the relief channels are constantly connected to a pressure sink R, in particular the atmosphere.

[0041] The control section 33 of the valve spool 24 is such that, in the first main switching position of the valve spool 24, the feed channel 31a communicates with the first working channel 31b and simultaneously the second working channel 31c communicates with the second relief channel 31e. This causes the pressure medium in the fluid-actuated actuator 13 to be fed into the first working chamber 17 and simultaneously the pressure medium in the second working chamber 18 to be pushed out to the pressure sink, resulting in the first stroke 19 of the piston 16.

[0042] In the second main switching position according to Fig. In section 5, the second working channel 31c is connected to the feed channel 31a, and the first working channel 31b is simultaneously connected to the first relief channel 31b. This drives the piston 16 to the second stroke 20, since pressure medium is fed from the feed channel 31a into the second working chamber 18, and at the same time the first working chamber 17 is relieved of pressure via the first relief channel 31d.

[0043] In this embodiment, the pressure medium used to actuate the valve spool 24 is branched off from the feed channel 31a within the valve housing 21. Branch channels (not shown) provide a continuous fluid connection between the feed channel 31a and each of the two pilot valve units 28a, 28b for this purpose.

[0044] In order to implement the desired energy-saving function simply and cost-effectively, the valve slide 24 is divided into several axially successive length sections according to the illustrated embodiment, which are displaceable relative to each other and relative to the valve housing 21 in the axial direction of the longitudinal axis 23.

[0045] The valve spool 24 is subdivided into two separate spool components, referred to as sub-spools, which, for clarity, will be called the first sub-spool 38a and the second sub-spool 38b. Depending on its relative position with respect to the valve body 21, the first sub-spool 38a controls the fluid flow between the first working channel 31b, the feed channel 31a, and the first relief channel 31d. Similarly, the second sub-spool 38b controls the fluid flow between the second working channel 31c, the feed channel 31a, and the second relief channel 31e, depending on its relative position with respect to the valve body 21.

[0046] Advantageously, the valve slide 24 is designed with spring means 39 which ensure that the two partial slides 38a, 38b are constantly biased in the direction of an axially separated relative position. The two partial slides 38a, 38b assume this axially separated relative position according to Fig. 3 and Fig. 5 then activates when the valve spool 24 is positioned in one of its two energy-saving switching positions. Stopping means 40 belonging to the valve spool 24 limit the movement of the two sub-spools 38a, 38b apart and, through mutual interaction, define the axially separated relative position. The two sub-spools 38a, 38b cannot move further apart axially than the axially separated relative position defined by the stopping means 40.

[0047] For example, in Fig. As shown in Figure 3, the spring means 40, according to a preferred embodiment, comprise a mechanical spring, which is expediently designed as a compression spring. The mechanical spring is received in a spring receiving chamber 41 formed in one of the two partial slides 38a, 38b, preferably in the first partial slide 38a.

[0048] For example, how Fig. As shown in Figure 3, the two partial slides 38a, 38b are coupled to each other via a coupling element 42. In the illustrated embodiment, the coupling element 42 is pin- or bolt-shaped and has a coupling head 43 to which a coupling shaft 44 with a smaller diameter extends longitudinally along the longitudinal axis 23 of the slide receptacle 22. The coupling head 43 is a multifunctional component, as it is relatively movably mounted in the spring receptacle 41 of the first partial slide body 39a and forms a support surface 45 for the mechanical spring at its free end. At the other end of the coupling head 43, which faces the coupling shaft 44, an annular stop surface 46 is formed, which is part of the stop means 50.

[0049] In the example shown, the coupling element 42 is connected to the second partial slide 38b, specifically attached to the second partial slide body 39b, for example by an external thread 47 formed on the coupling shaft 44, which is screwed into a threaded receptacle 48 formed in the second partial slide body 39b. The threaded receptacle 48 extends from an end face 49 of the second partial slide body 39b into the interior of the partial slide body 39b in a blind-hole manner. The coupling element 42 thus protrudes from the end face 49 of the second partial slide body 39b and projects towards the first partial slide body 39a. In addition, a particularly cylindrical opening 52 is formed on the first partial slide body 39a of the first partial slide, which also opens from an end face 51 into the spring receiving space 41 and is penetrated by the coupling shaft 44 of the coupling element 42.The diameter of the coupling head 43 is larger than the diameter of the opening 52, so that the coupling head located in the spring receiving chamber 41 is "trapped" even during the relative movement of the coupling element in the spring receiving chamber. Thus, the aforementioned annular stop surface 46 on the coupling head, together with a frontal wall section surrounding the opening 42 into the spring receiving chamber 41, forms a stop that defines the maximum open position of the two partial slides 38a, 38b.

[0050] For example, how Fig. As shown in Figure 4, a support member 53 is located at the other end of the spring receiving chamber 41, which closes the spring receiving chamber at its end. The mechanical spring can be supported on the support member 53, which is shown by way of example in the form of a spherical body. The spring is then supported on one side by the support surface 45 of the coupling head 43 and on the other side by the support member 53, and consequently, when the two partial slides 38a, 38b move towards each other, it is tensioned in the form of a compression spring.

[0051] A key aspect of the invention is a safety relief device 54 associated with the valve spool 17, which is equipped with at least one relief element. In the energy-saving position, the relief element 55 can be moved into an open position allowing fluid flow from the separated working channel 31b, 31c into the feed channel 31a.

[0052] This makes it possible to completely vent the fluid power device 11 if the pressure source on the feed channel 31a is no longer available, meaning that the working chamber 17, 18 of the drive 13, which is filled with "energy-saving pressure", can also be relieved via the feed channel, i.e., in particular vented.

[0053] As especially in the Fig. As shown in Figures 7 to 9, the relief element 55 of the safety relief device 54 is designed as a check valve, which has a check valve element 56 that is movable depending on the pressure difference between the working channel 31b, 31c and the feed channel 31a relative to the slide body of the valve slide 24.

[0054] Since, according to the illustrated embodiment, an energy-saving switching position can be switched after the respective main switching position, i.e., there are a total of two energy-saving switching positions, both partial slides 38a, 38b have a relief element 55 in the form of the check valve, each of which has a check valve element 56a, 56b movable relative to the associated partial slide body 39a, 39b.

[0055] In the example shown, the check valve element 56 is part of a sealing ring 35 of the sealing structure 34 or is designed as a sealing ring 35 itself. Like the other sealing rings 35, the sealing ring 35 designed as a check valve element is also received in an annular groove 36, whereby this check valve annular groove has a significantly larger axial dimension than the other annular grooves, meaning that the received sealing ring is movable in the associated annular groove 36 in the axial direction. The sealing ring 35, which forms the check valve element 56, is thus movable in the energy-saving position between a basic position sealing the passage between the working channel 31b, 31c and in the feed channel 31a and a release position in which at least part of the sealing ring 35 rests against a contact surface 60 of the partial slide body 39a, 39b equipped with a control edge 57.

[0056] Advantageously, the sealing ring is made of rubber-elastic material, whereby the movement between the shut-off position and the release position takes place through material deformation of the sealing ring.

[0057] A special feature of the illustrated directional control valve 12 is that the valve spool 24 can be switched from either of the two main switching positions to an energy-saving switching position that differs from the two main switching positions. This energy-saving switching process can be triggered by changing the force applied to at least one actuator section 26a, 26b. The in Fig. The first energy-saving switching position shown in Figure 4 can be reached from the first main switching position and is characterized by the fact that the first working channel 31b is completely closed off by the valve slide and has no fluid connection to either the feed channel 31a or to any of the relief channels 31d or 31e. The second working channel 31c, however, remains, as in the first main switching position, separated from the feed channel 31a and connected to the second relief channel 31e.

[0058] For the second energy-saving switching position, which can be set from the second main switching position, the same conditions apply with a reversed diagram. Here, the first working channel 31b remains unchanged, connected to the first relief channel 31d and disconnected from the supply channel 31a, while the second working channel 31c is disconnected not only from all relief channels 31d and 31e, but also from the supply channel 31a.

[0059] With regard to the connected fluid-actuated drive 13, this means that in each energy-saving switching position, the working chamber 17 or 18, which was still connected to the pressure source P in the preceding main switching position, is disconnected from the pressure source P, and the remaining stroke of the piston 16 is caused solely by the already supplied and confined pressure medium. This is sufficient to ensure a sufficiently high stroke speed, with the advantage that the degree of occupancy of the working chamber 17, 18 responsible for the stroke movement is limited, and consequently, compressed air consumption is reduced.

[0060] The operating mode of the directional control valve can be described as follows: The starting point for an operating cycle to generate a back-and-forth movement of the piston 16 between the two stroke end positions is the one from Fig. 3. The first main switching position of the valve slide 24 is evident. This first main switching position is characterized by the fact that the first partial slide 38a is acted upon by the drive force and rests against the second partial slide 38b, for example, by the fact that the two opposing end faces 49, 51 of the first and second partial slide bodies 39a, 39b are in contact with each other, or alternatively, that the drive piston rests against a support surface on the first partial slide 38a. This means that the two partial slides 38a, 38b assume the axially moved relative position, overcoming the opposing restoring force of the spring means 40.

[0061] In this first main switching position, the first working chamber 17 is supplied with pressure medium from the first working channel 31b, while at the same time the second working chamber 18 is depressurized via the second working channel 31c, so that the piston 16 and thus the entire drive unit 15 executes the first stroke movement 19 from the first stroke end position, with the full final pressure supplied by the pressure source P.

[0062] During the first stroke 19, before the piston 16 reaches the second stroke end position, the valve spool 24 is switched from the first main switching position to the first energy-saving switching position. The timing of this can be controlled, for example, by a timer or by a sensor responding to the drive unit 15.

[0063] Switching to the first energy-saving position is achieved by removing the drive force from the first partial slide 38a. This is done, for example, by venting the first drive chamber 30a. At this point, no corresponding drive force acts on the second partial slide 38b, just as in the first main switching position. As a result, the second partial slide 38b remains in its current position, while the first partial slide, now no longer subjected to the drive force, is moved relative to the second partial slide 38a and the valve housing 21 by the restoring force of the spring elements 40.In this position, the two partial sliders 38a, 38b assume the axially separated relative position, which is specified by the stop means 50, that is, the annular stop surface 46 on the rear of the coupling head 43 abuts the wall of the spring receiving chamber 41.

[0064] Thus, the second working channel 31c remains pressure-relieved via the second relief channel 31e, allowing the piston 16 to continue its first stroke 12. The first working channel 31b, however, is now disconnected from the pressure source P – and, incidentally, still from the first relief channel 31d – so that no further pressure medium flows into the first working chamber 17. Consequently, the piston 16 completes its first stroke 12 solely through the volume of pressure medium supplied to the first working chamber 17 during the first main switching position. While this leads to a drop in fluid pressure in the first working chamber 17, it does not significantly affect the movement of the piston 16, as it was strongly accelerated by the full nominal pressure during the first main switching position, resulting in high dynamics.Due to the lack of a further flow of pressure medium, the consumer pressure medium in the first working chamber 17 remains at a low level.

[0065] In the first energy-saving switching position, a safety venting of the pressure medium remaining in the first working chamber is possible, namely when the pressure source is removed from the feed channel 31a via the return from the working chamber 17 via the first working channel 31b into the feed channel 31a.

[0066] The safety relief device used for this purpose has the aforementioned sealing ring 35, which is movable relative to the associated first partial slide body 39b due to the pressure difference between the sealing shut-off position and the release position, and thereby folds down to the support surface 49 on the partial slide body 39b in the sense of a check valve element and thus opens a fluid passage between the first working channel 31b and the feed channel 31e.

[0067] To then reverse the stroke movement of the piston 16, the directional control valve 12 is moved into the Fig. The second main switching position is shown in Figure 5. This occurs because, while no driving force is applied to the first partial slide 38a, the drive section 26d of the second partial slide 28b is now actuated by the corresponding activation of the pilot valve assembly 27, so that it is subjected to the driving force. This driving force moves the valve 24 into the second main switching position, whereby the first partial slide 38a is moved a short distance from the position it occupied in the first energy-saving switching position until the movement of the second partial slide is stopped by the stop means 50. During the movement of the second partial slide, the spring means, i.e., the mechanical spring, are also tensioned, whereby in the second main switching position the two partial slides 38a and 38b are again moved into a relative position.In this now set second main switching position, the fluid-actuated drive 13 is off compared to the first main switching position. Fig. 3 is fluidically controlled with reversed signs. The second working chamber 18, connected to the second working channel 31c, is connected to the pressure source P and supplied with a pressure medium at nominal pressure. Simultaneously, the first working chamber 17, connected to the first working channel 31b, is pressure-relieved via the first relief channel 31c. Thus, the second stroke movement 20 takes place with maximum dynamics.

[0068] Before the end of the second stroke, i.e., before the piston 16 returns to the first stroke end position, the valve slide 17 is moved from the second main switching position to the position shown above. Fig.The second energy-saving switching position is activated. This occurs similarly to the above description by removing the drive force acting on the second partial slide 38b – for example, by venting the second drive chamber 30b – so that the second partial slide 38b is moved into the extended relative position due to the spring force of the spring elements.

[0069] In the second energy-saving switching position, a safety venting of the pressure medium located in the second working chamber of the drive is also possible via the second working channel and the feed channel 31a, whereby the sealing ring assigned to the second partial slide body 39b is moved from the shut-off position to the release position. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 205 722 B3

[0002] JP 2000-130616 A

[0003] DE 10 2011 010 566 A1

[0004]

Claims

[1] Directional control valve, comprising a valve housing (21) in which a spool receptacle (22) extending axially through between two end-face end walls (29a, 29b) is formed, in which a valve spool (24) equipped with a spool body is arranged, which is axially switchable between two main switching positions, in which it alternately connects one working channel (31b, 31c) to a feed channel (31a) opening into the spool receptacle (22) and simultaneously the other working channel (31b, 31c) to a relief channel (31d, 31e) opening into the spool receptacle (22), wherein the valve spool (24) has at least one actuation section (26a, 26b),which can be acted upon by a driving force that drives the valve slide (24) to switch its position, and wherein the valve slide (24) can be switched from at least one of the two main switching positions by an energy-saving switching operation into an energy-saving switching position that differs from the main switching positions, in which it separates the other working channel (31b, 31c) from the feed channel (31a) while maintaining the fluid connection between one working channel (31b, 31c) and a relief channel (31d, 31e) that is open in the main switching position before the energy-saving switching operation, wherein the valve slide (24) has two partial slides (38a, 38b) arranged axially successively in the slide receptacle (22), which are held in a position predetermined by stopper means (50) of the valve slide (24) by spring means (40).are pre-tensioned in an axially separated relative position and are axially movable both uniformly and relative to each other in the slide receptacle (22), whereby in the energy-saving switching position they assume an axial relative position that differs from their axial relative positions present in the main switching position, characterized by , that the valve slide (24) is associated with a safety relief device (54) equipped with at least one relief element (55), such that the relief element (55) can be moved in the energy-saving switching position into an open position allowing fluid flow from the separated working channel (31b, 31c) into the feed channel (31a). [2] Directional control valve according to claim 1, characterized by, that the safety relief device (54) has at least one relief element (55) in the form of a check valve which has a check valve element (56) which is movable depending on the pressure difference between the working channel (31b, 31c) and the feed channel (31a) relative to the slide body of the valve slide (24). [3] Directional control valve according to claim 1 or 2, characterized by , that the two partial slides (38a, 38b) each have a check valve element, each of which has a check valve element (56) movable relative to the associated partial slide body (39a, 39b). [4] Directional control valve according to claim 2 or 3, characterized by , that the check valve element (56) is designed as part of a sealing ring (55) or as a sealing ring (55) which is part of a sealing structure (34) which participates in the switching movement of the valve slide (24). [5] Directional control valve according to claim 4, characterized by, that the sealing ring (35) is seated in an annular sealing ring receptacle of a control section (33) of the associated partial slide body (39a, 39b) and is movable in the energy-saving switching position between a basic position sealing the passage between the working channel (31b, 31c) and the feed channel (31a) and a release position in which at least a part of the sealing ring (35) rests against a contact surface (60) of the partial slide body (39a, 39b) equipped with a control edge. [6] Directional control valve according to claim 5, characterized by , that the sealing ring (35) consists at least partially of rubber-elastic material and that the movement between the shut-off position and the release position takes place through material deformation of the sealing ring (35). [7] Directional control valve according to one of the preceding claims, characterized by, that the valve slide (24) can be switched from both main switching positions to an energy-saving switching position that differs from the main switching position by means of an energy-saving switching operation, wherein the two energy-saving switching positions differ from each other. [8] Directional control valve according to one of the preceding claims, characterized by , that the at least one drive section (26a, 26b) has a drive surface (25a, 25b) defining a drive chamber (30a, 30b) of the slide receptacle (22), which can be actuated with a drive pressure medium in a controlled manner to drive the valve slide (24), wherein the drive section (26a, 26b) is expediently a drive piston of the valve slide. [9] Directional control valve according to any one of the preceding claims, characterized by, that the fluid connection between the feed channel (31a) and one of the two working channels (31b, 31c) and one of the two relief channels (31d, 31e) can be controlled by each of the two partial slides (38a, 38b) depending on the switching position of the valve slide (24). [10] Directional control valve according to any one of the preceding claims, characterized by that the spring means are formed by at least one air spring and / or at least one mechanical spring. [11] Directional control valve according to one of the preceding claims, characterized by , that the two partial sliders (38a, 38b) assume the axially separated relative position in every energy-saving switching position of the valve slider (24). [12] Directional control valve according to one of the preceding claims, characterized by, that at least one of the two partial slides (38a, 38b) has a drive section (26a, 26b) that can be acted upon by a drive force, wherein the valve slide (24) can be moved into one of the main switching positions by the actuation of this drive section (26a, 26b), wherein at the same time the two partial slides (38a, 38b) can be moved into an axially relative position by overcoming the restoring force of the spring means. [13] Directional control valve according to claim 12, characterized by , that the two partial sliders (38a, 38b) assume the axially relative position to each other in every main switching position. [14] Directional control valve according to one of the preceding claims, characterized by, that at least one of the partial slides (38a, 38b), preferably only one of the two partial slides (38a, 38b), has a spring receiving space (41) formed in its partial slide body (39a, 39b) extending in the axial direction of the partial slide body (39a, 39b), in which spring means (40) in the form of a mechanical spring, in particular a compression spring, are received. [15] Directional control valve according to one of the preceding claims, characterized by , that the two partial slides (38a, 38b) are coupled to each other via a coupling element (42) in particular a pin-like form, such that the coupling element (42) is attached on the one hand to one of the partial slides (38a, 38b) to its partial slide body (39a, 39b) and on the other hand is coupled to the other partial slide (38a, 38b) in a relatively movable manner, allowing the partial slides (38a, 38b) to move apart and towards each other in a relative position. [16] Directional control valve according to claim 15, characterized by, that the coupling element (42) has a coupling head (43) forming a component of the stop means (50) which is received in a cavity, in particular spring receiving space (41), of the partial slide body (39a, 39b) of the other partial slide (38a, 38b), wherein the coupling head (43) is movable into a stop position, defining the separated relative position of the two partial slides (38a, 38b). [17] Directional control valve according to claim 16, characterized by , that the mechanical spring is supported on one side by a support member (53) and on the other side by the coupling head (43).

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