DEVICE AND VALVE FOR FLOW FORCE COMPENSATION

Description

[0001] The invention relates to a proportional pressure control valve with the features in the preamble of claim 1.

[0002] Such a device is used in a valve for supplying pressure to a hydraulic consumer, for example, a vehicle clutch or brake, at a preset pressure. The hydraulic consumer to be supplied is connected to the service port. Control movements of the regulating piston, corresponding to the preset pressure, open the fluid connection between the pressure supply port and the service port, and fluid is directed from the pressure supply to the hydraulic consumer.

[0003] DE 10 2014 004 796 A1 discloses an exemplary proportional pressure control valve with a control piston longitudinally guided in a valve housing, which, by means of an actuating system, serves to selectively connect connection points located in the valve housing, such as a pressure supply connection, a consumer connection, and a tank or return connection. The actuating system is designed in the form of a magnetic system; however, actuation by means of a pneumatic or other fluidic actuator or by means of a mechanical actuating system is also possible.

[0004] The control process for supplying the hydraulic consumer is also influenced by so-called flow forces on the device's control piston, caused by the pressures and flow rates to be controlled at the connection points. These flow forces are typically caused by a pressure drop at the corresponding control edge in the housing, for example, in the area between the pressure supply connection and the operating connection. This pressure drop generates a force in the direction of the actuating system connected to the device, which attempts to move the control piston towards its closed position, thereby further reducing the set pressure.

[0005] A device for compensating undesirable flow forces on a control piston axially displaceable within a valve housing, caused by the opening and closing of control edges, is known from DE 10 2016 105 203 A1. In the known device, a control groove for compensating flow forces, which reduces or eliminates the disturbances, has a flow-force-compensated control edge geometry. Here, a step-like compensation element is formed in the region of the control edge on the control piston, with the step creating an annular flow-in surface for the fluid. The known solution still leaves something to be desired with regard to improving flow force compensation.

[0006] Further facilities are detailed in US 3 324 890, US 4 941 508 and US 2004 / 0000347 A1.

[0007] Starting from a device known from the prior art, the invention aims to make the flow force compensation on the control piston even more effective and to enable an individual design of the flow force compensation in the area of ​​the control edge.

[0008] This problem is solved by a device having all the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0009] Because the control piston is hollow at one free end, and because, in a device according to the invention, the shape change also follows a step function whose function graph has at least one more step than the number of steps required to form the control edge, the flow attack surface is divided into at least two sub-surfaces according to the shape of the step function. This results in optimized force transmission to the control piston by the fluid acting on the flow attack surface. Due to the control edge following a step function and the shape change also following a step function, a fluid space is created in the area where the control piston passes over the control edge according to the control positions. The fluid can flow into this space to act on the flow attack surface and flow past the control edge.According to the force formula F = P x A, a counterforce to the flow force is generated during operation of the device, which attempts to pull the control piston into an open position opposite to the closed position. The design of the function graph of the step function, in particular the number and dimensions of the individual steps, enables a demand-oriented compensation of the flow force at the change in shape specified by the function graph.

[0010] In a preferred embodiment of the device according to the invention, each step on the control piston forms an annular surface that is concentric with and perpendicular to the longitudinal axis of the control piston. The annular surfaces can be easily formed on the control piston and enable a uniform force application along the entire circumference of the control piston. The individual annular surfaces form the flow surface for the fluid. Preferably, the connecting surfaces of the annular surfaces run parallel to the longitudinal axis of the control piston. However, it is also conceivable that the stepped function has a profile with surfaces arranged at an angle to each other that deviates from 90°. For example, it is conceivable that the annular surfaces are inclined relative to a perpendicular orientation.

[0011] In a further preferred embodiment of the device according to the invention, the individual, adjacent annular surfaces of the steps on the control piston are spaced apart from one another by stepped surfaces that run concentrically to the longitudinal axis and parallel to it. The stepped function on the control piston thus consists of a sequence of annular surfaces and stepped surfaces. Stepped surfaces running parallel to the longitudinal axis of the control piston allow unimpeded flow to the annular surfaces that serve as the flow attack surface. However, it is also conceivable to design the stepped surfaces on the control piston in a manner deviating from a parallel orientation, preferably with a slight inclination relative to a parallel orientation.

[0012] In a further preferred embodiment of the device according to the invention, the respective annular surface is smaller when viewed in the direction of the outer circumference of the control piston than the annular surfaces adjoining it inwards. In this embodiment, the stepped function is not regularly formed, and the individual annular surfaces have different radial extents. The radial extent of the individual annular surfaces decreases from the inside to the outside along the control piston, thereby achieving improved flow force compensation such that the fluid first acts on the annular surface with the largest extent and then on annular surfaces with a smaller extent, and is guided past the change in shape and the opposite control edge by the stepped design.

[0013] Furthermore, it is advantageous that the respective step surface, viewed along the outer circumference of the control piston parallel to its longitudinal axis, has a smaller height than the innermost step surface. Due to the different heights of the step surfaces, the annular surfaces have different distances from each other in the axial direction. Depending on the design of the stepped function, the annular surfaces have the same or different extents in the radial direction, and the step surfaces have the same or different heights, or extents, in the axial direction, thus enabling the required design of the shape change in the fluid space and the associated flow force compensation at the control piston.

[0014] In a further preferred embodiment of the device according to the invention, if there are more than two stages of the function graph, the outermost step surface arranged on the control piston is followed by a step surface of the same height for each stage. This results in the advantage of a uniform arrangement and spacing of the annular surfaces used for fluid action to compensate for flow forces.

[0015] Preferably, the shoulder surface located on the innermost part of the control piston transitions into at least one fluid passage within the control piston. Upon reaching or passing over the control edge, the corresponding fluid connection between the connection points is opened or closed via this at least one fluid passage. The direct transition from the respective fluid passage to the shoulder surface, as part of the deformation, prevents further potentially disruptive fluid flows and directly initiates flow force compensation through the fluid reaching the deformation.

[0016] In a preferred embodiment of the device according to the invention, the step for forming the control edge at the pressure supply connection is formed by a transition point between at least one associated fluid passage in the housing and the inner wall of this housing, along which the control piston is movably guided. This offers the advantage that when actuating the fluid connection from the pressure source to the hydraulic consumer, or from the pressure supply connection to the service connection, a counterforce to the actuating force acting on the control piston is achieved as a flow force compensation.

[0017] In a further preferred embodiment of the invention, in the direction of travel of the control piston to close the respective passage with the control edge, the stepped sequence of control edge and control piston ascends from the outside inwards in one direction of travel and descends from the inside out in the opposite direction of travel. The stepped sequence of control edge and control piston, ascending or descending depending on the direction of travel, is always selected to be the same, thus defining a fluid chamber with substantially the same flow width. Particularly preferably, the stepped functions provided on the control edge and the control piston have the same function graph, apart from the at least one further step formed on the control piston.

[0018] Furthermore, it is advantageous that the steps on the control piston open into an inner recess on the outer circumference of the control piston, which opens into another step at the opposite end, interacting with a control edge of a tank connection. This achieves flow force compensation when actuating the fluid connection between the service port and the tank connection. Advantageously, a fluid passage is formed on the control piston in the area of ​​the inner recess, defining a fluid path via a central recess to the service port.

[0019] In a preferred embodiment of the device according to the invention, the control edge at the tank connection is formed by at least one associated through-hole in the valve housing. Preferably, the pressure supply connection and the tank connection are arranged radially on the outside of the valve housing, particularly preferably via annularly arranged through-holes, and the service connection is preferably formed at an axial end of the valve housing.

[0020] In a further preferred embodiment of the device according to the invention, the length of the inner recess, viewed parallel to the longitudinal axis of the control piston, corresponds to the direct distance between two adjacent control edges of the pressure supply connection and the tank connection. This offers the advantage of opening and closing the fluid connections with short control movements of the control piston. The inner recess formed on the control piston serves as part of the fluid connection between the tank and the service connection point, which is controlled via the control edge.

[0021] Advantageously, at least one additional fluid passage opens into the inner recess of the control piston, which is connected via a central recess in the control piston to the first fluid passage in the same piston. Depending on the control piston's position, the fluid reaches the pressure supply connection or the tank connection via the central recess.

[0022] Furthermore, it is advantageous that an orifice device is connected to each additional fluid passage point in the control piston. This orifice device connects the central recess of the control piston, which is permanently fluid-carrying and connected to the service port in the valve housing, to another central recess in the control piston, into which a control device for the control piston engages, at least partially. This results in the advantage of a compact design for the control piston with its integrated fluid connections and control device.

[0023] Furthermore, it is advantageous that the control piston, outside the inner recess and the irregular shape with the stepped function, has the same outer diameter, which is preferably interrupted by integrated sealing and / or guide bands. The cylindrical control piston is guided longitudinally in a cylindrical bore in the housing and actuates the connection points formed in the housing.

[0024] Preferably, a pressure supply connection and a tank connection are radially integrated into the valve housing, and a service connection is formed at the axial end of the valve housing. The flow force compensation device ensures that the pressure required to supply the hydraulic consumer is maintained without disruptive flow forces that would pull the control piston into its closed position.

[0025] Further advantages and features of the invention will become apparent from the figures and the following description of the drawing. The features mentioned above and those listed below can each be implemented individually or in any combination in a device and a valve according to the invention. The features shown in the figures are purely schematic and not to scale. They show: Fig. 1a a longitudinal section through an exemplary valve designed according to the invention; Fig. 1b the design of the shape modification used for flow force compensation in an enlarged view; Fig. 2a a part of a housing of the valve according to the Fig. 1a with the device according to the invention for flow force compensation in a longitudinal section; Fig. 2b the embodiment of a shape change used for flow force compensation in an enlarged view; Fig. 2c an alternative embodiment of the shape change used for flow force compensation in an enlarged view similar to the solution according to the Fig. 1b ; Fig. 3a a further embodiment of a device according to the invention for flow force compensation in a partially perspective view, shown on a control piston as it is used in the valve according to the Fig. 1a is used; Fig. 3b the design of the shape change used for flow force compensation according to the Fig. 3a in enlarged view; and Fig. 3 shows an alternative embodiment of the shape change used for flow force compensation in enlarged view, as it is used in a control piston according to the Fig. 3a is used.

[0026] Fig. 1a The longitudinal section shows a valve designed as a 3-way proportional pressure regulating valve with a control piston 12 guided longitudinally within a valve housing 10. The control piston 12, which includes a valve pilot control 14, serves to selectively connect connection points formed in the valve housing 10: a pressure supply connection point P, a service connection point A, and a tank connection point T. The service connection point A is located in the direction of view towards Fig. 1a Viewed from the left end, the control piston 12 is inserted axially into the valve housing 10. The pressure supply connection P and the tank connection T are each radially integrated into the valve housing 10 as individual, annularly arranged bores. The control piston 12 is supported against a first compression spring 16, which acts as an energy storage device. The first compression spring 16 is supported at one free end against the control piston 12, which is hollow at this end. At its other end, the first compression spring 16 is supported in the recess of an orifice seat body 18. The orifice seat body 18, which is stationary in the valve housing 10, has a longitudinal bore 20 that forms a valve seat for a seat cone 22 at one end, while a damping orifice 24 is provided at the opposite end.The seat cone 22 is clamped between a second compression spring 26 and a third compression spring 28 with different spring stiffnesses, the spring tension of the third compression spring 28 being adjustable via a spindle drive 30. When the seat cone 22 lifts from the orifice seat body 18 against the force of the third compression spring 28, due to the pressure conditions in the valve and supported by the second compression spring 26, a fluid-carrying connection is opened from the damping orifice 24 via the pilot seat into transverse channels 32 in the orifice seat body 18. The transverse channels 32 transition into at least one longitudinal channel 34, which leads to the tank connection point T. To form the respective longitudinal channel 34, the valve housing 10 is enclosed by a cartridge-like additional housing part 36.Depending on the pressure setting via the mechanical valve pilot control 14, the pressure relief valve opens towards the tank connection point T as soon as a predefinable pressure threshold is exceeded, in order to protect the hydraulic circuit with the connected work machines and equipment from damaging pressure spikes or a corresponding damaging pressure increase.

[0027] The control piston 12, which is supported on the first compression spring 16, provides access to the service port A as shown in the illustration. Fig. 1a The control piston 12 is connected to the pressure supply connection point P in a fluid-carrying manner, or, when the control piston 12 moves longitudinally into at least one further control position where it moves towards a stop 38 in the valve housing 10, it is connected to the tank connection point T. For this purpose, the control piston 12 has a central recess 40, which extends from the end of the control piston 12 associated with the service connection point A to the fluid passages 42 arranged annularly on the control piston 12. In each further control position of the control piston 12, the fluid passages 42 serve as a fluid connection from the service connection point A to the tank connection point T. Offset from the fluid passages 42 towards the service connection point A, further fluid passages 44 are formed on the control piston 12, which are located in the Fig. 1a The control piston 12 in the shown position serves to connect the fluid from the service connection point A to the pressure supply connection point P. A connecting part 46 and a further central recess 48, into which the first compression spring 16 engages, adjoin the central recess 40 of the control piston 12. A further longitudinal bore 50 is provided in the connecting part 46 of the control piston 12. An orifice device 52 is inserted into the further longitudinal bore 50, so that in every position of travel of the control piston 12 a fluid-carrying connection is ensured between the central recess 40, which adjoins the service connection point A, and the further central recess 48, which adjoins an interior space 54 between the control piston 12 and the orifice seat body 18.

[0028] To actuate the pressure supply connection point P, the control piston 12 passes over a control edge 56 formed on the valve housing 10. To actuate the tank connection point T, the control piston 12 passes over another control edge 58, which is also formed on the valve housing 10. In the area of ​​the control edge 56 of the valve housing 10, the control piston 12 has a change in shape 60 from its otherwise external, cylindrical basic shape in the illustrated embodiment. The detailed design of the change in shape 60 is shown in the Fig. 1b to deduce which the in Fig. 1a The area marked X is shown at 10x magnification. The shape change 60 follows a step function whose graph has three steps, two more than the single-step control edge 56. On the control piston 12, the steps form a first annular surface 62, a second annular surface 64, and a third annular surface 66, each concentric to the longitudinal axis R (see figure). Fig. 2a ) of the control piston 12 and perpendicular to it. The individual, adjacent ring surfaces 62, 64, 66 are spaced apart from each other by a first shoulder surface 68 and a second shoulder surface 70, which are concentric to the longitudinal axis R (cf. Fig. 2a The contours of the control piston 12 extend along the outer circumference and parallel to it. The first annular surface 62 and the second annular surface 64, measured from the outer circumference of the control piston 12, have approximately the same radial extent, whereas the third annular surface 66 has a larger radial extent. The two shoulder surfaces 68 and 70 have approximately the same height when viewed along the outer circumference of the control piston 12. In this particular configuration of the contour change 60, the fluid acts on annular surfaces 62 to 66 with different radial extents to compensate for flow forces, thereby ensuring optimized force transmission to the control piston 12 and good fluid flow through the fluid space defined by the contour change 60, past the control edge 56.Particularly preferred is the radial extent of the individual ring surfaces 62 to 66 chosen such that the ring surfaces 62 to 66, which have different diameters, each have the same area.

[0029] Fig. 2a shows a longitudinal section through a valve housing 10 of a device designed according to the invention, as a component of the valve according to the Fig. 1a The valve housing 10 is equipped with a control piston 12 that is longitudinally movable within the housing 10. The valve housing 10 has a total of three fluid connection points: the service connection A, which is axially integrated into the valve housing 10, and the pressure supply connection P and the tank connection T, which are radially formed on the valve housing 10. The control edges 56, 58 of the pressure supply connection P and the tank connection T are each formed by several radially integrated passages 72, 74 in the valve housing 10. The passages 72 associated with the tank connection T are arranged along a circular ring on the valve housing 10, as are the additional passages 74 associated with the pressure supply connection P.The respective step for forming the control edge 56 at the pressure supply connection point P is formed by a transition point between the further passage points 74 in the valve housing 10 and the inner wall 76 of the valve housing 10, along which the control piston 12 is guided to move.

[0030] As the enlarged view of the Fig. 2b As shown, the control edge 56 is single-stage and the shape change 60 on the control piston 12 is two-stage. The radially outer first annular surface 62 has a smaller radial extent than the adjacent second annular surface 64. The annular surfaces 62 and 64, which are concentric to and perpendicular to the longitudinal axis R of the control piston 12, are spaced apart from each other by a first shoulder surface 68, which is concentric to and parallel to the longitudinal axis R. The second shoulder surface 70 adjoins the second annular surface 64 and transitions into the further fluid passage 44 in the control piston 12. When the control piston 12 passes over the control edge 56, the fluid connection from the pressure supply connection point P via the inner recess 78 of the control piston 12 to the service connection point A is opened through the further fluid passages 44.Accordingly, when the control piston 12 passes over the further control edge 58, the fluid connection from the service connection point A via the central recess 40 and fluid passage points 42, 44 to the tank connection point T is released.

[0031] The stages of the shape change 60 on the control piston 12 open into an inner recess 78 of the control piston 12, which is arranged radially opposite the inner wall 76 of the valve housing 10 and which opens at the axially opposite end into a further stage 80, which interacts with the further control edge 58 of the tank connection T.

[0032] In the direction of the longitudinal axis R, the aperture device 52 in the control piston 12 is connected to the respective fluid passage point 42, which in Fig. 1a depicted and, for the sake of simplicity, in Fig. 2a not shown, and which connects the permanently fluid-carrying central recess 40 of the control piston 12 to the further central recess 48 in the control piston 12. A Fig. 2a The control device for the control piston 12 is not shown in detail. The control device is preferably part of a magnetic system (not shown), but actuation by means of a pneumatic or other fluidic actuating drive as well as a mechanical actuation system is also possible.

[0033] An alternative design for a design change 60 with three stages is in Fig. 2c As shown, a first annular surface 62, a second annular surface 64, and a third annular surface 66 are spaced apart from each other by a first shoulder surface 68 and a second shoulder surface 70, with a third shoulder surface 82 transitioning into the further fluid passage 44. The radially inner, third annular surface 66 has the greatest radial extent.

[0034] Fig. 3a Figure 1 shows a perspective side view of the control piston 12, which is rotationally symmetrical to the longitudinal axis R, with the fluid passages 42, 44 formed therein in the area of ​​the inner recess 78. Fig. 3a It is clearly evident that the control piston 12, outside the inner recess 78 and the shape change 60 adjacent to the other fluid passage points 44, has the same outer diameter with the stepped function, which is interrupted by radially circumferential constrictions 84 that represent pressure relief grooves. At the connection point A associated with the service connection, in Fig. 3a The control piston 12 tapers at the end shown below. The constrictions 84 are formed at regular axial intervals on the outer circumference of the control piston 12.

[0035] In Fig. 3b The detailed design of the shape change 60 following a step function is shown. In the 3-stage shape change 60, the first annular surface 62, the first step surface 68, the second annular surface 64, and the second step surface 70 each have the same extent in the radial and axial directions, respectively. The third annular surface 66 is larger, viewed in the direction of the outer circumference of the control piston 12, than the annular surfaces 62 and 64 that adjoin it to the outside. The illustration of the Fig. 3b In addition to the constriction 84 in the control piston 12, it is also clearly evident that the control piston 12 has a slight indentation in the area of ​​the inner recess 78 in the drawing, which results from the graphic representation when a bore is introduced at the place of a shoulder.

[0036] The in Fig. 3c The alternative design of the shape change 60 shown differs from the one in Fig. 3b The embodiment shown is characterized by the fact that one step, and thus one less annular surface and one less shoulder surface, is provided, so that from the outer circumference of the control piston 12 a first annular surface 62, a first shoulder surface 68 and a second annular surface 64 with a larger radial extent compared to the first annular surface 62 are formed.

[0037] Different requirements for flow force compensation are due to the different viscosity of the fluid used, the operating temperature and pressures, as well as the design of the control piston 12, which is movably arranged in the valve housing 10. The in the Fig. 1b , 2b , 2c , 3b und 3cThe different configurations of the shape change 60 on the control piston 12 shown enable optimized flow force compensation adapted to the respective control situation via the annular surfaces 62 to 66, which together form the flow attack surface for the fluid. When the associated control edge 56 is traversed, a flow passage for the fluid is formed according to the step function defined by the shape change 60. In the illustrated embodiments, the control edge 56 is designed as a single step; however, step functions with more than one step on the control edge 56 are also conceivable.Due to different radial and axial extensions of the ring surfaces 62 to 66 and the shoulder surfaces 68, 70, 82, different function graphs of the step function are specified and, in addition to a different attack of the flowing fluid, a different flow behavior is achieved past the shape change 60 and the control edge 56.

Claims

1. Proportional pressure control valve which supplies a consumer with a predefinable consumer pressure and which preferably can be connected to a hydraulic drive system, comprising a valve housing (10) having at least two fluid ports (A, P, T), a control device for moving a control piston (12) between the individual control positions, and a device consisting of the control piston (12), which is guided so as to be longitudinally displaceable in the housing (10) having the at least two connection points (A, P, T) for fluid, and which interacts with a control edge (56), which follows a step function, of the housing (10) at a pressure supply connection point (P), which supplies a different connection point (A), serving as a work port, with fluid at a predefinable pressure via a fluid connection in control positions of the control piston (12) and, in the process, owing to flow forces that arise, attempts to pull it towards a closed position that shuts off said fluid connection, wherein, for the purpose of flow force compensation, the control piston (12) has such a shape change (60) in the region of the control edge (56) of the housing (10) compared with its otherwise external basic shape that a flow impact surface for fluid is created, which flow impact surface causes force to be applied to the control piston (12) in a compensatory manner counter to the flow force, and this application of force attempts to pull the control piston (12) into an open position in the opposite direction to the shut-off position, wherein a first compression spring (16) is supported, by a free end, on the control piston (12), characterised in that the control piston (12) has a hollow bore at said end, and in that the shape change (60) likewise follows a step function, the function graph of which has at least one more step than the number of steps required for forming the control edge (56).

2. Proportional pressure control valve according to claim 1, characterised in that each step on the control piston (12) forms an annular surface (62, 64, 66) that runs concentrically with the longitudinal axis (R) of the control piston (12) and perpendicularly thereto.

3. Proportional pressure control valve according to claim 1 or claim 2, characterised in that the individual adjacent annular surfaces (62, 64, 66) of the steps on the control piston (12) are spaced apart from one another by means of shoulder surfaces (68, 70) that run concentrically with the longitudinal axis (R) and in parallel therewith.

4. Proportional pressure control valve according to any of the preceding claims, characterised in that, when viewed in the direction of the external circumference of the control piston (12), each annular surface (62, 64, 66) is smaller than or the same as the respective inwardly adjoining annular surfaces (62, 64, 66).

5. Proportional pressure control valve according to any of the preceding claims, characterised in that, when viewed in parallel with the longitudinal axis (R) of the control piston (12), each shoulder surface (68, 70) has, in the direction of the external circumference of said control piston, a smaller height than or the same height as the innermost shoulder surface (82).

6. Proportional pressure control valve according to any of the preceding claims, characterised in that, when the function graph of the shoulder surface (68) arranged outermost on the control piston (12) has more than two steps, a shoulder surface (70) of the same height comes thereafter for one step.

7. Proportional pressure control valve according to any of the preceding claims, characterised in that the shoulder surface (82) arranged innermost on the control piston (12) merges into at least one fluid passage point (44) in the control piston (12).

8. Proportional pressure control valve according to any of the preceding claims, characterised in that the step for forming the control edge (56) at the pressure supply port (P) is formed by a transition point between at least one associated passage point (74) in the housing (10) and the internal wall (76), along which the control piston (12) is displaceably guided, of that housing (10).

9. Proportional pressure control valve according to claim 8, characterised in that, in the direction in which the control piston (12) travels in order to close the relevant passage point (74) together with the control edge (56) in one displacement direction of the control piston, the sequence of steps of the control edge (56) and shape change (60) on the control piston (12) rises in said direction when viewed from the outside in and falls in the opposite displacement direction when viewed from the inside out.

10. Proportional pressure control valve according to any of the preceding claims, characterised in that the steps of the shape change (60) on the control piston (12) open into an internal recess (78) on the external circumference of the control piston (12), said internal recess opening out at the opposite end in a further step (80) that interacts with a control edge (58) of a tank port (T).

11. Proportional pressure control valve according to claim 10, characterised in that the control edge (58) on the tank port (T) is formed by at least one associated passage point (72) in the valve housing (10).

12. Proportional pressure control valve according to claim 10 or claim 11, characterised in that, when viewed in parallel with the longitudinal axis (R) of the control piston (12), the length of the internal recess (78) is equal to the direct distance between two adjacent control edges (56, 58) of the pressure supply port (P) and the tank port (T).

13. Proportional pressure control valve according to any of claims 10 to 12, characterised in that at least one further fluid passage point (42) opens into the internal recess (78) on the control piston (12) and is in fluid communication with the at least one fluid passage point (44) in the control piston (12) by means of a central recess (40) in said control piston.

14. Proportional pressure control valve according to claim 13, characterised in that an orifice device (52) in the control piston (12) is connected to each further fluid passage point (42) and brings the central recess (40) of the control piston (12), which central recess is in permanent fluid communication with the work port (A) in the valve housing (10), into fluid communication with a further central recess (48) in the control piston (12), in which further central recess a control device for the control piston (12) engages at least in part.

15. Proportional pressure control valve according to any of claims 10 to 14, characterised in that, outside the internal recess (78) and the shape change (60) having the step function, the control piston (12) has the same external diameter, which is preferably broken up by sealing strips and / or guide strips installed therein.