Pilot control electromagnetic valve

Abstract

The utility model relates to a valve, in particular to a proportional valve, which is provided with a main piston for controlling the volume flow of a main body and a pilot control piston (12) for controlling the volume flow of pilot control, the main piston and the pilot control piston (12) can be guided in a valve shell (14) in a longitudinal movement manner, and the pilot control piston (12) can be controlled by means of a magnetic device. The position of the main piston can be adjusted by means of the pilot control piston (12) in such a way that a fluid pressure acting on the main piston is transmitted via a fluid connection (18) into a pilot control chamber (20) having the pilot control piston (12), the pilot control piston holds the main piston in its closed position which blocks the volume flow of the main body when the magnetic device is not actuated, and the pilot control piston (12) is moved into a position in which the volume flow of the main body is blocked when the magnetic device is actuated. In this position, the fluid pressure decreases in the pilot control chamber (20) in a decoupled manner from the pressure supply via the main piston until the main piston reaches an open position in which the volume flow of the main body is regulated.

Description

Technical Field

[0001] The utility model relates to a valve, in particular a proportional valve, which has a main piston for controlling a main volume flow and a pilot control piston for controlling a pilot control volume flow, wherein the main piston and the pilot control piston are guided in a longitudinally movable manner in a valve housing, and the pilot control piston can be actuated by means of a magnetic device. Background Art

[0002] DE10323595A1 discloses a valve, in particular a valve in the form of a proportional seat valve or a sliding valve, which has a valve housing and at least three fluid interfaces passing through the valve housing, as well as a main piston guided in the valve housing and a pilot control piston for pilot control, the pilot control piston being controllable by means of an energizable magnetic device, wherein, when the pilot control device is opened, the fluid passes from one of the two interfaces controllable by the main piston via a cross-sectional contraction in the main piston and the pilot control device to a third interface controllable by the pilot control piston, and, due to the resulting pressure drop, the main piston reaches a corresponding control position in which the two fluid interfaces can be controlled by the fluid quantity.

[0003] EP2880315B1 discloses a valve, in particular a pilot-controlled proportional directional seat valve, which comprises a valve housing having a fluid inlet and a fluid outlet, wherein a fluid flow between the inlet and the outlet can be adjusted by a main piston, a pilot-controlled valve chamber is arranged on the back side of the main piston, the pilot-controlled valve chamber has a pilot-controlled valve closure member movable by an operating device, by means of which the fluid flow between the pilot-controlled valve chamber and the fluid outlet can be adjusted, an inlet throttle plate is arranged between the fluid inlet and the pilot-controlled valve chamber, an opening cross section of the inlet throttle plate can be reduced by a control element, the inlet throttle plate has a plurality of throttle holes, an opening cross section of at least one of the throttle holes can be reduced by a control element, and dividing the inlet throttle plate into a plurality of throttle holes can realize switching the inlet throttle plate to a plurality of opening stages.

[0004] In this way, the pilot-controlled directional valve uses electrohydraulic actuation to control the start, stop and direction of the volume flow and the speed, acceleration and deceleration of the hydraulic consumer connected to the valve, for example in the form of a hydraulic working cylinder. The pilot-controlled directional valve is used in principle where a large volume flow is controlled under small flow losses. However, small flow losses in the case of high volume flow mean a large opening cross section and therefore a large stroke of the main piston. The disturbance that affects the valve function is the flow force and friction force that react on the switching movement, which depends on the volume flow and the pressure difference, that is, the valve power. In particular, in the case of mechanical actuation by a spring that is usually in the form of a return spring, the measured value of the spring force relative to the friction force may be too small for returning the piston slide valve. In order to meet the requirements of the magnetic system in terms of stroke and force, the magnetic system must either be dimensioned accordingly or hydraulically pilot-controlled valves. As shown above, the following valves are known in the prior art for such applications, and these valves must therefore have hydraulic pilot control devices. Utility Model Content

[0005] Starting from this prior art, the object of the present invention is to further improve the known valve with regard to its functional properties.

[0006] To this end, the utility model proposes a valve, which has a main piston for controlling a main volume flow and a pilot control piston for controlling a pilot control volume flow, the main piston and the pilot control piston are guided in a longitudinally movable manner in a valve housing, and the pilot control piston can be operated by means of a magnetic device, wherein the position of the main piston can be adjusted by means of the pilot control piston, in which the fluid pressure acting on the main piston is transmitted to a pilot control chamber having the pilot control piston via a fluid connection structure, the pilot control piston holds the main piston in its closed position that blocks the main volume flow when the magnetic device is not operated, and when the magnetic device is operated, the pilot control piston moves to the following position, in which the fluid pressure in the pilot control chamber continues to decrease in a manner decoupled from the pressure supply via the main piston until the main piston reaches an open position that adjusts the main volume flow.

[0007] Due to the characteristic part of the valve according to the utility model, the position of the main piston can be adjusted by means of a pilot control piston, in which the fluid pressure acting on the main piston is transmitted to a pilot control chamber having a pilot control piston via a fluid connection structure, and the pilot control piston holds the main piston in its closed position blocking the main volume flow when the magnetic device is not operated, and moves the pilot control piston to the following position when the magnetic device is operated, in which the fluid pressure in the pilot control chamber continues to decrease in a manner decoupled from the pressure supply via the main piston until the main piston reaches an open position for adjusting the main volume flow, generally providing improved regulation quality with low pressure loss and avoiding leakage when the valve according to the utility model is operated.

[0008] The valve solution according to the invention, in particular the magnetic force of the magnetic device, enables a linear adjustment of the position of the main piston while compensating for the flow forces and sealing friction occurring on the main piston. In this case, it is advantageously possible that the pilot control piston can overcome the force of the accumulator. The force of the magnetic device Manipulation, where friction is taken into account The pilot control piston is essentially pressure-compensated in the case of: Since the pilot control piston is thus in a force balance during the opening movement of the main piston for controlling the main volume flow between two possible fluid connection points in the valve housing, the stroke of the main piston can be adjusted by the pilot control device. This has no corresponding situation in the prior art.

[0009] It is particularly advantageous if the main piston is coupled to a displacement measuring device for detecting its position. Due to the advantageous actuation of the main piston by the pilot control piston, the valve according to the invention with a correspondingly small-sized magnetic device is sufficient in the range of the volume flow to be controlled with a reduced opening cross section, for which only a small stroke of the main piston is required. This results in a highly dynamic proportional throttle valve.

[0010] In a specific embodiment, the pilot control piston is configured as a hollow piston, which has a first recess on its outer circumference, which establishes a connection with the guide fluid of the main piston when the magnetic device is not operated and forms a channel for the guide fluid with its inner circumference, the channel opens with one free end into the pilot control chamber and opens through a channel section of the channel into a second recess on the outer circumference of the hollow piston, and when the magnetic device is operated, the hollow piston moves into the tank interface in the valve housing so that the first recess is separated from the connection to the guide fluid of the main piston.

[0011] In a specific embodiment, a switching valve is connected to the fluid-conducting connection between the main piston and the pilot control chamber, which switches the correspondingly higher pressure of the two fluid interfaces in the valve housing as a transmission pressure into the pilot control chamber, through which the main volume flow is guided.

[0012] In a specific embodiment, a fluid chamber is provided in the main piston as part of the fluid connection structure, and the fluid chamber communicates with a further fluid chamber between the valve housing and the main piston via at least one connecting channel in the main piston, and the further fluid chamber communicates with a first recess in the pilot control piston via at least one further connecting channel in the valve housing with at least partial overlap.

[0013] In one specific embodiment, at least one further connecting channel is arranged in the pilot control piston and in the valve housing, by means of which the second recess on the pilot control piston can be connected to the tank.

[0014] In a specific embodiment, the main piston is held in the direction of its closed position by means of a further energy accumulator.

[0015] In one specific embodiment, the respective energy accumulator is formed by a compression spring, and the compression spring for the main piston surrounds the compression spring for the pilot control piston with a higher spring rate than the compression spring for the pilot control piston.

[0016] In one embodiment, the main piston has a radius at least partially of convex spherical design on its free end side in order to establish a linear relationship between the stroke of the main piston and the opening area resulting therefrom at one of the fluid connections in the valve housing.

[0017] In a specific embodiment, the pilot control piston is penetrated by a measuring rod, which is a part of a displacement measuring device for the main piston connected to the main piston. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The valve according to the present invention is explained in detail below with the aid of an embodiment according to the drawings. Here, a longitudinal section is shown in principle and not to scale:

[0019] Figure 1 The main components of the valve are shown;

[0020] Figure 2 In the closed valve position, the Figure 1 a front portion of the valve; and

[0021] Figure 3 The valve is open when the Figure 2 . DETAILED DESCRIPTION

[0022] The valve shown in the drawing is a so-called proportional valve and has a main piston 10 for controlling the main volume flow. In addition, there is a pilot control piston 12 for controlling the pilot control volume flow, wherein the main piston 10 and the pilot control piston 12 are guided together in a longitudinally movable manner in a valve housing 14. Figure 1 It turns out that the pilot control piston 12 is arranged displaceably in the valve housing 14 by means of the magnetic device 16 .

[0023] The position of the main piston 10 can be adjusted by means of the pilot control piston 12 by transmitting the fluid pressure acting on the main piston 10 via the fluid connection 18 to a pilot control chamber 20 with the pilot control piston 12, which, when the magnetic device 16 is not actuated, holds the main piston 10 in its closed position that blocks the main volume flow, as in the case of Figure 2 , wherein, when the magnetic device 16 is actuated, the pilot control piston 12 moves into a position in which the fluid pressure in the pilot control chamber 20 decreases decoupled from the pressure supply via the main piston 10 until the main piston 10 reaches the open position for regulating the main volume flow, as shown in FIG. Figure 1 and 3 As shown by way of example for one of the possible open positions.

[0024] The pilot control piston 12 can be driven against the force of an energy accumulator in the form of a compression spring 22. The opposing force of the magnetic device 16 operation, where the friction force for the valve is taken into account In the case of , the pilot control piston 12 is essentially pressure-compensated, in which case:

[0025] or

[0026]

[0027] Opposing forces and exist Figure 3 This is indicated by force arrows 26 or 28.

[0028] As can also be seen from the figures, the pilot control piston 12 is designed as a hollow piston, which has a first recess 30 in the form of an annular groove on its outer circumference, which first recess is formed according to the attached diagram when the magnetic device 16 is not actuated. Figure 2The pilot control piston 12 designed as a hollow piston has a fluid-conducting channel 32 along its inner circumference, which opens with one free end 34 into the pilot control chamber 20 and opens via a radially extending channel section 36 of the axially extending channel 32 into a second recess 38 in the form of an annular groove on the outer circumference of the hollow or pilot control piston 12, which, when the magnetic device 16 is actuated, opens according to the second recess 38 in the form of an annular groove. Figure 1 and 3 36 is moved into the tank connection 40 in the valve housing 14 in such a way that a fluid-carrying connection to the tank connection 40 is established, but the first recess 30 is separated from the fluid-carrying connection to the primary piston 10. Both the channel section 36 and the tank connection 40 can be present in multiples as shown. In any case, a switching valve 42 is connected to the fluid-carrying connection between the primary piston 10 and the pilot control chamber 20, so that the respectively higher pressure in the two fluid connections 44, 46 in the valve housing 14, through which the main volume flow to be regulated is conveyed to the pilot control chamber 20 as a transmission pressure.

[0029] If the fluid pressure at the fluid connection 44 is greater than the fluid pressure at the fluid connection 46, the fluid with the higher pressure reaches the switching valve 42 with its closing ball 48 via the fluid connection 44 and the longitudinal channel 50 in the front region of the primary piston 10. Such a closing ball 48 moves to the right in the viewing direction of the drawing and closes the radial channel 52 introduced in the primary piston 10, which opens into the fluid connection 46 in the valve housing 14. A further longitudinal channel 56 is connected to the valve chamber 54 of the switching valve 42 in the primary piston 10, which opens with its free end end into a fluid chamber 58 in the primary piston 10. The fluid chamber 58 is connected to a further fluid chamber 62, which is designed as an annular chamber and is arranged between the valve housing 14 and the primary piston 10, via two connecting channels 60 arranged in the primary piston 10 at an inclined angle of 45° to the longitudinal axis of the valve. Next, the further fluid chamber 62 transitions fluidically into an annular chamber 64 arranged in the valve housing 14 and from there a longitudinal channel section 66 is guided into a further annular chamber 67 and then into a transverse channel section 68 in the valve housing 14 which widens in cross section at its inner end towards the pilot control piston 12 and which is arranged in accordance with the invention. Figure 2 The diagram can be placed in superposition with the flow of the annular first recess 30 at the outer circumference of the pilot control piston 12, wherein according to Figure 1 and 3Such a fluid-conducting connection can be cut off by the movement of the pilot control piston 12 from right to left under the action of the magnetic device 16. It is easy to understand that the corresponding channels and other connections can be arranged on the valve body in multiples as required as shown. In any case, the components 50, 52, 54, 56, 58, 60, 62, 64, 66, 67, 68 and 30 form a fluid connection structure 18 between the fluid interface 44 on the end side of the main piston 10 and the pilot control chamber 20 between the main control piston 10 and the pilot control piston 12. In this regard, the pressure on the fluid interface 44 in the closed valve position of the main piston 10 is further guided or further transmitted to the pilot control chamber 20.

[0030] If the pressure at the radial connection 46 as the further fluid connection in the valve housing 14 is greater than the pressure at the fluid connection 44, the switching valve 42 is switched in the viewing direction of the drawing in such a way that the closing ball 48 now occupies its left closed position, which closes the channel 50. The fluid with a predeterminable pressure thus reaches the further longitudinal channel 56 via the fluid connection 46 and the radial channel 52 and the valve chamber 54, so that the rest of the fluid connection 18 to the pilot control chamber 20 is now released via such a path. Usually, the fluid pressure of a pressure supply device, such as a hydraulic pump, should be present at the fluid connection 44, and a hydraulic consumer, such as a hydraulic cylinder, should be connected to the fluid connection. Other assignments of the fluid connections 44, 46 are conceivable.

[0031] As can be further seen from the accompanying drawings, the main piston 10 consists of two parts 70, 72, wherein such parts, with their free ends facing each other, define a fluid chamber 58 as seen in the axial displacement direction of the valve pistons 10, 12. A second pressure spring 74 acts as a further energy accumulator on the free end side of the second part 72 facing the magnetic device 16, and the second pressure spring is supported with its other free end on a stationary part of the valve housing 14. A pressure spring 22 extends on the inner circumference of the second pressure spring 74 and is arranged coaxially therewith, and the pressure spring is supported with one free end on a shoulder in the shape of a shoulder in the interior of the second part 72 and with its other free end on an annular projection 76 on the pilot control piston 12. In this way, both the main piston 10 and the pilot control piston 12 are prestressed by the two pressure springs 22, 74, the spring forces of which together produce the quantity in the above formula: .

[0032] How to control the movement of the main piston 10 will now be described. Figure 2 From the observation direction, the main piston 10 moves to the right as shown in FIG. Figure 1 and Figure 3In the state predetermined in the embodiment, the following is done here. The pressure in front of the main piston 10 at the corresponding fluid connection 44 or 46 (which is transmitted to the pilot control piston 12 via the switching valve 42 and the fluid connection structure 18) is controlled by the magnetic device 16 when it is not energized. Figure 2 The pressure in the pilot control chamber 20 of the diagram maintains the primary piston 10 by the area difference formed by the opposite end sides of the primary piston 10 .

[0033] If a force is now generated by the magnetic device 16, when the magnetic force is greater than the friction force plus the spring force, the pilot control piston 12 moves to the left in the viewing direction of the drawing and the lateral pressure supply of the main piston 10 is closed by such a leftward movement of the pilot control piston 12, which is in accordance with Figure 1 and 3 The closed outer circumference of the pilot control piston 12 in the illustration closes the transverse channel section 68 in the valve housing 14. In such a closed position, however, the pilot control chamber 20 is connected to the tank via the second recess 38 of the fluid-conducting channel 32 in the pilot control piston 12 via the two tank connection openings 40 extending radially in the valve housing 14, which open at their respective free ends into a deepening annular channel 78 on the outer circumference of the pilot control piston 12 in each of its displacement positions. The annular channel 78 transitions into a pressure relief chamber 80, the volume of which increases as soon as the pilot control piston 12 is displaced to the left, which establishes a fluid-conducting connection of the pilot control chamber 20 to the respective tank connection 40 via the fluid-conducting components 32, 36, 80, 78. By such a connection of the pilot control volume to the tank, the pressure in the pilot control chamber 20 drops and a new equilibrium occurs at the valve until the valve is completely closed.

[0034] In particular, the following overall situation results. The magnetic force decreases, so that the pilot control piston 12 opens the connection for the pressure supply of the main piston 10. In this case, the pilot control pressure increases and thus the pressure in the pilot control chamber 20 also increases. This causes the main piston 10 to move from right to left again, which causes the spring force of the compression springs 22 and 74 to decrease, so that a new equilibrium occurs according to the following formula:

[0035] .

[0036] The magnetic device 16 is used to control the pilot control piston 12. The magnetic device has a coil 81 that can be energized in a usual manner. The coil moves the magnetic armature 82 from right to left when energized, wherein the magnetic armature drives the pilot control piston 12 in a corresponding forced-guided manner via a hollow operating rod 84 and a clutch 86. In order to ensure the unimpeded movement of the pilot control piston 12, it is particularly provided that the clutch 86 that is freely movably guided in the clutch chamber 88 of the valve housing 14 is connected to the fluid-conducting channel 32 via a radial transverse hole 90, so that the pressure in the pilot control chamber 20 is connected via the channel 32 and the transverse hole 90 ( Figure 3 ) is also present in the clutch chamber 88, which in this respect is transferred to a magnetic system in the form of an actuating magnet in the form of a magnetic device 16 via a hollow actuating rod 84 on the outer and inner circumference in a pressure-balanced manner. Figure 2 The left side, when viewed in the observation direction, is a dead space 89 .

[0037] The space 89 is filled or emptied via at least one bore 91 in the component 86 , so that the dynamics or the damping of the valve can be adjusted via the corresponding bore 91 in the component 86 .

[0038] In addition, a measuring rod 92 is fixedly arranged on the second part 72 of the main piston 10, which passes through the pilot control piston 12 and the operating magnetic system so as to pass with its other free end area into a displacement measuring device represented as a whole by 94, which is provided with two measuring coils 96, which can detect the displacement movement of the main piston 10 in two directions in terms of measurement technology.

[0039] Such a displacement measuring system is known, for example, from DE 10 2012 014 250 A1 for a pressure balance.

[0040] In addition, if this is especially based on Figure 2 As shown in the illustration of , the primary piston 10 has a convex spherical end face 98 on its free end side, which is formed by a predeterminable radius, which is used to establish a linear relationship between the stroke of the primary piston 10 and the opening area formed by it at the fluid connection 44 or 46. Otherwise, the primary piston 10 is guided movably on the inner circumference of the valve housing 14 via a stepped annular surface in a longitudinally displaceable manner, and individual sealing ring systems, usually in the form of O-rings, ensure the fluid-tight delimitation of the individual fluid chambers and fluid paths as previously specified.

Claims

1. A valve having a main piston (10) for controlling a main volume flow and a pilot control piston (12) for controlling a pilot control volume flow, the main piston (10) and the pilot control piston (12) being guided in a longitudinally displaceable manner in a valve housing (14), and the pilot control piston (12) being actuable by means of a magnetic device (16), characterized in that: The position of the main piston (10) can be adjusted by means of the pilot control piston (12) in that the fluid pressure acting on the main piston (10) is transmitted via a fluid connection structure (18) to a pilot control chamber (20) having the pilot control piston (12), the pilot control piston holding the main piston (10) in its closed position blocking a main volume flow when the magnetic device (16) is not actuated, and when the magnetic device (16) is actuated, the pilot control piston (12) moves to a position in which the fluid pressure in the pilot control chamber (20) decreases in a manner decoupled from the pressure supply via the main piston (10) until the main piston (10) reaches an open position for regulating the main volume flow.

2. The valve according to claim 1, characterized in that The pilot control piston (12) can overcome the force of the accumulator The force of the magnetic device (16) Manipulation, where friction is taken into account In the case of .

3. The valve according to claim 1 or 2, characterized in that: The pilot control piston (12) is designed as a hollow piston, which has a first recess (30) on its outer circumference, which establishes a connection with the guide fluid of the main piston (10) when the magnetic device (16) is not actuated and forms a channel (32) for guiding the fluid with its inner circumference, the channel opening with its one free end (34) into the pilot control chamber (20) and opening through a channel section (36) of the channel (32) into a second recess (38) on the outer circumference of the hollow piston, and when the magnetic device (16) is actuated, the hollow piston moves into a tank connection (40) in the valve housing (14), so that the first recess (30) is disconnected from the connection with the guide fluid to the main piston (10).

4. The valve according to claim 1 or 2, characterized in that: A switching valve (42) is connected to the fluid-conducting connection between the main piston (10) and the pilot control chamber (20), which valve conveys the respectively higher pressure of two fluid connections (44, 46) in the valve housing (14) as a transmission pressure into the pilot control chamber (20), through which the main volume flow is conducted.

5. The valve according to claim 1 or 2, characterized in that: A fluid chamber (58) is provided in the main piston (10) as part of the fluid connection structure (18), the fluid chamber leading to a further fluid chamber (62) between the valve housing (14) and the main piston (10) via at least one connecting channel (60) in the main piston (10), the further fluid chamber leading to a first recess (30) in the pilot control piston (12) via at least one further connecting channel in the valve housing (14) with at least partial overlap.

6. The valve according to claim 1 or 2, characterized in that: At least one further connecting channel is arranged in the pilot control piston (12) and in the valve housing (14), by means of which a second recess (38) on the pilot control piston (12) can be connected to a tank.

7. The valve according to claim 1 or 2, characterized in that: The main piston (10) is held in the direction of its closed position by means of a further energy accumulator.

8. The valve according to claim 1 or 2, characterized in that: The respective energy storage device is formed by a compression spring, and the compression spring (74) for the main piston (10) surrounds the compression spring for the pilot control piston (12) with a higher spring rate than the compression spring (22) for the pilot control piston (12).

9. The valve according to claim 1 or 2, characterized in that: The main piston (10) has a radius at least partially in a convex spherical configuration on its free end side (98) in order to establish a linear relationship between the stroke of the main piston (10) and the opening area generated thereby at one of the fluid connections (44, 46) in the valve housing (14).

10. The valve according to claim 1 or 2, characterized in that: A measuring rod (92) passes through the pilot control piston (12), which is a part of a displacement measuring device (94) for the main piston (10) that is connected to the main piston (10).

11. The valve according to claim 1, characterized in that The valve is a proportional valve.

Images