DE102024201888A1 - Slide valve, on whose valve slide low flow forces act - Google Patents

Abstract

The invention relates to a slide valve (10) with a housing (20) and a valve slide (30), wherein the housing (20) has a slide bore (24) which is substantially circular-cylindrical with respect to a longitudinal axis (11), wherein the valve slide (30) is accommodated in the slide bore (24) in a manner which is linearly movable along the longitudinal axis (11), wherein the valve slide (30) has a first and a second web (31; 32), which each run annularly around the longitudinal axis (13), wherein they are each sealingly adapted to the slide bore (24), wherein the first and the second web (31; 32) are delimited from one another by a first groove (41) on the valve slide (30), wherein a first, a second and a third channel (21; 22; 23) are provided in the housing (20), wherein the first channel (21) thus extends into the slide bore (24) opens out in such a way that it can be brought into fluid exchange connection with the first groove (41).According to the invention, the first groove (41) is designed to be so wide in the direction of the longitudinal axis (13) that the first channel (21) is arranged in the region of the first groove (41) in every possible position of the valve slide (30), so that it is not covered by the first and second webs (31; 32).

Description

The invention relates to a slide valve according to the preamble of claim 1, a method for producing this slide valve and a hydraulic machine in which this slide valve is used.

From the DE 10 2021 207 837 A1 A slide valve is known which is optimized for use in a digital control circuit, whereby a corresponding control can be obtained, for example, from the DE 10 2019 219 451 A1 is known. For this application, it is particularly important that the relationship between the current in the control solenoid and the position of the valve spool follows a predetermined monotonic characteristic curve almost instantaneously and as precisely as possible. This instantaneousness is achieved by directly actuating the valve spool with the control solenoid. This results in small actuating forces. They are certainly sufficient to bring about a force equilibrium with the actuating spring. However, the dynamic flow forces in the spool valve and the resulting frictional forces between the valve spool and the spool bore can become so large that they cause considerable deviations from the specified characteristic curve. These deviations also vary over time and are subject to a disturbing hysteresis. DE 10 2021 207 837 A1 concerns a possibility of taking flow forces into account.

At the DE 10 2021 207 837 A1 An increase in the current in the actuating magnet causes the actuating cylinder on the axial piston machine to be connected to the tank, so that the axial piston machine shown is adjusted to the maximum displacement volume. Within the scope of the present invention, a slide valve is initially to be provided which, with the same connection dimensions and the same external dimensions, exhibits a reverse behavior. Within the scope of the present invention, it was decided to achieve this goal by forming the two adjustable orifices of the slide valve by a first and a separate second web on the valve slide, wherein DE 10 2021 207 837 A1 a single web forms both orifices. As a result, many measures have been taken to minimize the flow forces that are important for the slide valve according to DE 10 2021 207 837 A1 were found are no longer applicable. For example, the DE 10 2020 208 933 A1 , the DE 10 2021 207 650 A1 and the DE 10 2022 201 755 A1 referred to.

The object of the invention is to provide a slide valve according to the design explained above, which enables particularly high volume flows with a small size, whereby only low flow forces act on the valve slide, whereby in particular the flow forces acting radially to the longitudinal axis are minimized, so that the slide valve has a low hysteresis.

According to claim 1, it is proposed that the first groove be designed so wide in the direction of the longitudinal axis that the first channel is arranged in the region of the first groove in every possible position of the valve slide, so that it is not covered by the first and second webs. Due to the associated advantages, particular reference is made to the statements regarding 2 referred to.

With regard to the circular cylindrical slide bore, it should be noted that this is preferably manufactured with high precision in a single operation, even though it is interrupted by several grooves. For the purposes of this application, the slide bore is understood to mean the entire surface of the housing that lies on the same circular cylinder, even if this surface is not continuous.

Advantageous further developments and improvements of the invention are specified in the dependent claims.

It can be provided that a second groove is arranged in the housing adjacent to the first web, wherein the second groove extends annularly around the longitudinal axis, forming a continuously adjustable first aperture with a first end face of the first web facing the first groove, wherein the second channel opens at least partially into the second groove. The second channel breaks the radial symmetry of the slide valve and can thus cause flow forces directed radially to the longitudinal axis. This effect, in particular, is minimized by the features mentioned above.

It can be provided that a third groove is arranged in the housing adjacent to the second web, wherein the third groove extends annularly around the longitudinal axis, forming a continuously adjustable second orifice with a second end face of the second web facing the first groove, wherein the third channel opens at least partially into the third groove. The third channel breaks the radial symmetry of the slide valve and can thus cause flow forces directed radially to the longitudinal axis. This effect, in particular, is minimized by the aforementioned features.

It can be provided that a control edge assigned to the first and/or the second orifice is formed on the first or second web over its entire circumference with a constant, essentially sharp-edged cross-sectional shape. Within the scope of the present invention, it is preferred if the first and/or the second web are narrow, while still having a good sealing effect. Although it would be conceivable to provide the chamfer explained further below on the valve slide, this would run counter to the above objective. It has also been shown that the chamfer explained further below on the housing influences the flow more strongly in the sense of the invention than a chamfer on the valve slide. In particular, the DE 10 2005 030 173 A1 Known fine control notches on the valve spool are essentially useless within the scope of the present invention. The valve spool would have to be secured against rotation for a variable chamfer on the valve spool to have the desired effect on the radial flow forces. This is not necessary with the preferred control edge, which is constant over the circumference.

It can be provided that a counter-control edge assigned to the first and/or the second orifice, which in each case forms a transition from the slide bore to the second or third groove, is in each case designed as a chamfer whose angle of inclination to the longitudinal axis is between 20° and 40°. The said angle of inclination is preferably measured in a measuring plane which contains the longitudinal axis. The chamfer preferably runs endlessly around the longitudinal axis, wherein the angle of inclination is most preferably constant over the entire circumference. The sectional image of the chamfer in every possible measuring plane is preferably a straight line. The said angle of inclination is preferably approximately 31°.

It can be provided that a length of the chamfer, which is measured in the direction of the longitudinal axis, changes along a circumference of the chamfer with respect to the longitudinal axis. It can be provided that a depth of the chamfer, which is measured radially to the longitudinal axis, changes along a circumference of the chamfer with respect to the longitudinal axis. If the angle of inclination of the chamfer is constant, as is preferably the case, the length and depth of the chamfer change proportionally to one another. It has been shown that precisely by varying these dimensions the flow forces acting radially to the longitudinal axis on the valve spool can be minimized. The effective direction of the said variation relative to the position of the first to third channels is constant because the relative position of the said features on the housing is fixed.

It can be provided that the first, second, and third channels are arranged substantially in a common reference plane, with the length and/or depth of the chamfer being greatest in the region of the reference plane. It can be provided that a reference side is arranged on the side of the longitudinal axis on which the first, second, and third channels are arranged, with the length and/or depth of the chamfer being greatest on the reference side. With this configuration of the chamfer, the radially acting flow forces can be minimized particularly effectively.

It can be provided that a separate fourth groove is assigned to each of the second and/or third grooves in the housing, wherein the fourth groove is arranged further away from the first channel than the respective second or third groove, so that the slide bore is present in sections between the fourth groove and the assigned second or third groove, wherein the second or third channel also opens into the respective fourth groove. The slide bore present in sections between the aforementioned grooves then forms a disruptive contour for the flow, which influences the flow forces in the sense of the invention.

Protection is also claimed for a method for producing a slide valve according to the invention, wherein a blank of the housing is provided in which a raw contour of the chamfer is rotationally symmetrical with respect to the longitudinal axis, wherein then by means of a milling or grinding tool which is inserted into the slide bore, further material is removed from the raw contour of the chamfer at two or more points which are spaced apart from one another in the circumferential direction with respect to the longitudinal axis in order to obtain a final contour of the chamfer. With this type of machining, the shape of the chamfer can be produced easily and with high precision. It should be noted here that even the smallest dimensional changes of the chamfer can significantly influence the flow. The axis of rotation of said milling or grinding tool is preferably arranged parallel to the longitudinal axis. The feed direction of the milling cutter preferably runs radially to its axis of rotation.

It can be provided that the milling or grinding tool is advanced exclusively radially to the longitudinal axis during the aforementioned removal of further material. This allows the chamfer shape according to the invention to be achieved in a particularly simple manner.

It may be provided that the milling or grinding tool during the mentioned To remove additional material, the feed is first advanced radially to the longitudinal axis, followed by a circumferential advance with respect to the longitudinal axis. The advance in the circumferential direction can be, for example, 20°, with 360° corresponding to the entire circumference of the chamfer. By varying the advance in the circumferential direction, the effect according to the invention can be optimized in a particularly simple manner.

Protection is further claimed for a hydraulic machine whose displacement volume is adjustable by means of an actuating cylinder, wherein the hydraulic machine comprises a slide valve according to the invention, wherein the first channel is connected to the actuating cylinder, wherein the second channel is connected to a pressurized fluid source, wherein the third channel is connected to a pressurized fluid sink, wherein the slide valve comprises a control magnet and a control spring, wherein a position of the valve slide is defined exclusively by the balance of forces between the force of the control magnet, the force of the control spring and the forces caused by the flow of the pressurized fluid between the first, the second and the third channel, wherein a controller is provided whose control variable is an electric current in the control magnet. Without the optimization of the flow forces according to the invention, such a hydraulic machine would not function satisfactorily.

The housing of the slide valve is preferably rigidly connected to another housing part of the hydraulic machine. The forces caused by the flow also include indirectly caused forces, such as the frictional forces between the slide bore and the valve slide, which increase due to the radially acting flow forces.

The controller is preferably implemented using a digital computer. Apart from the aforementioned flow forces, no further hydraulic actuating forces act on the valve spool that influence its position. In particular, no hydraulic pilot control is provided. The proposed direct control of the valve spool allows the best possible control quality to be achieved. However, this presupposes that the aforementioned flow forces, which are unavoidable in practice, are considerably smaller than the actuating forces of the actuating magnet and the actuating spring. This very goal can be achieved cost-effectively with the spool valve according to the invention. The actuating magnet is preferably designed as an electromagnet, which preferably comprises an electrical coil and a ferromagnetic armature, wherein the coil is traversed by the aforementioned electrical current, and the valve spool can be subjected to a force by the armature.

The hydraulic machine is preferably an axial piston machine, which is most preferably designed in a swash plate construction, wherein it comprises a pivoting cradle, the pivoting position of which can be adjusted with the actuating cylinder.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

• 1 einen Schaltplan eines Hydrauliksystems mit einer Hydromaschine, welche ein erfindungsgemäßes Schieberventil umfasst, welches wiederum im Längsschnitt dargestellt ist;
• 2 einen vergrößerten Ausschnitt von 1 im Bereich des ersten und des zweiten Stegs;
• 3 eine perspektivische Schnittansicht des Gehäuses des Schieberventils, in welcher eine Gegensteuerkante mit der Fase sichtbar ist; und
• 4 eine grobschematische Ansicht des Schleifwerkzeugs zur Herstellung der Fase und des umgebenden Gehäuses.

The invention is explained in more detail below with reference to the accompanying drawings. They show:

• 1 a circuit diagram of a hydraulic system with a hydraulic machine which comprises a slide valve according to the invention, which is again shown in longitudinal section;
• 2 an enlarged section of 1 in the area of the first and second bridge;
• 3 a perspective sectional view of the housing of the slide valve, in which a counter control edge with the chamfer is visible; and
• 4 a rough schematic view of the grinding tool used to produce the bevel and the surrounding housing.

1 shows a circuit diagram of a hydraulic system 50 with a hydraulic machine 51, which includes a slide valve 10 according to the invention. The slide valve 10 is shown in longitudinal section, wherein the section plane contains the longitudinal axis 13.

The hydraulic machine 10 is designed, for example, as an axial piston machine with a swash plate design. Typically, the hydraulic machine 10 draws pressurized fluid from a pressurized fluid sink 54, in particular from a tank 55, at a low-pressure port 58 and delivers it to a high-pressure port 59. Depending on the operating state of the hydraulic system 50, the hydraulic machine 51 may be motor-driven, with the pressurized fluid flowing from the high-pressure port 59 to the low-pressure port 58. The pressurized fluid is preferably a liquid, most preferably hydraulic oil. From the high-pressure port 59, the pressurized fluid flows to a consumer 63 and from there back to the tank 55. The consumer 63, which is roughly schematically depicted as a throttle, may comprise one or more hydraulic cylinders and/or one or more hydraulic motors, the speed of movement of which can each be controlled by an associated valve.

The displacement volume of the hydraulic machine 10 is adjustable in this case using an actuating cylinder 52 and an optional auxiliary actuating cylinder 64, each of which is designed as a single-acting cylinder. The actuating cylinder 52 has a larger piston area than the auxiliary actuating cylinder 64. Pressurizing the actuating cylinder 52 reduces the displacement volume. Pressurizing the auxiliary actuating cylinder 64 increases the displacement volume. The different piston areas result in a reduction in the displacement volume when both the actuating cylinder 52 and the auxiliary actuating cylinder 64 are subjected to pressure at the high-pressure connection 59. It is understood that the effect of the auxiliary actuating cylinder 64 can also be achieved in other ways, for example, by arranging the pivot axis of the pivoting cradle away from the rotational axis of the drive shaft of the hydraulic machine.

In the present case, the pressure fluid source 53 for adjusting the displacement volume is formed by the high-pressure connection 59 of the hydraulic machine 51, although it can also be formed by a separate control oil pump. The pressure there is measured by a pressure sensor 57, which is connected to a controller 56. The controller 56 is preferably implemented digitally, using a programmable digital computer. An actual variable of the controller 56 is the pressure measured by the pressure sensor 57, although other actual variables can also be used, for example, the pivot angle of the hydraulic machine. The manipulated variable of the controller 56 is the electrical current flowing in the actuating magnet 15 of the slide valve 10 according to the invention. The control loop is thus closed via a digitally operating element, so that the advantages of a purely hydraulic control loop, namely the high achievable forces within the control loop, are lost. As a result, special attention must be paid to the design of the slide valve, especially with regard to the flow forces occurring there.

The pressurized fluid source 53 is permanently connected to the auxiliary actuating cylinder 64. When de-energized, the slide valve 10 establishes a connection between the pressurized fluid sink 54 and the actuating cylinder 52, resulting in a reduction in the displacement volume, preferably adjusted toward zero. However, it is also conceivable for the adjustment to occur beyond zero, so that the delivery direction of the hydraulic machine 51 is reversed while the rotation direction of the drive motor 65 remains constant.

The pressure in the actuating cylinder 64 is provided by a spool valve 10. The spool valve 10 is designed as a continuously adjustable 3/2-way valve, which is directly adjusted by means of a control solenoid 15. The spool valve 30 is thus designed in the simplest possible manner, in particular, without hydraulic pressure control, in which the pressure in the actuating cylinder 52 acts on the valve spool 30 in the direction of the longitudinal axis 13.

The slide valve 10 comprises a valve slide 30, which is accommodated in a circular cylindrical slide bore 24 so as to be movable in the direction of a longitudinal axis 13. The valve slide 30 has a first and a second web 31; 32, which are sealingly adapted to the slide bore 24. The first and the second web 31; 32 run around the longitudinal axis 13, being spaced from each other by a first groove 41. In the housing 20 of the slide valve 10, a second, a first and a third channel 22; 21; 23 are arranged, which are arranged next to each other in the specified order along the longitudinal axis 13, opening at least indirectly into the slide bore 24 transversely to the longitudinal axis 41. The middle, first channel 21 is permanently connected to the actuating cylinder 52. The 1 left, second channel 22 is permanently connected to the pressure fluid source 53, whereby the 1 right, third channel 23 is permanently connected to the pressure fluid sink 54. By moving the valve slide 30, a fluid connection can be established between the first and the second channel 21; 22 or a fluid connection between the first and the third channel 21; 23. In a middle position of the valve slide 30, which in 1 As shown, all channels 21; 22; 23 can optionally be connected to one another via a small throttle cross-section or completely closed off from one another.

In the direction of the longitudinal axis 13, the valve spool 30 is acted upon by the force of a control magnet 15. Opposite the control magnet 15, the valve spool 30 is acted upon by the force of a control spring 16. The control spring 16 is supported by a screw plug 29, which is screwed into the housing 20.

The pressure relief channels 67; 66 in the valve spool 20 and in the housing 30 are permanently connected to the third channel 23 and the pressure fluid sink 54, respectively. The two opposite end faces of the valve spool 30 are accordingly subjected to the same, low pressure at the pressure fluid sink 54, so that in total no force acts on the valve spool 30. The two auxiliary webs 36 at the opposite ends of the valve spool 30 seal this low pressure against the second or third channel 32; 33.

The actuating magnet 15 comprises a fluid-tight pole tube 60 made of a ferromagnetic material such as steel. A substantially circular-cylindrical armature 62 is accommodated within the pole tube, movable along the longitudinal axis 13. Inside the pole tube 60, the pressure prevails at the pressure relief channel 66. The armature 62 is also made of a ferromagnetic material such as steel. An electrical coil 61 is arranged around the pole tube 60, which is preferably provided with a connection socket, to which the controller 56 is connected.

The adjusting spring 16 pushes the valve slide into its 1 right end position, in which a fluid exchange connection exists between the first and the third channel 21; 23. The armature 62 is also pressed into its right end position via the separate push rod 68. When the electrical coil 61 is supplied with an electrical current, a force acts on the valve spool 30 via the push rod 68 in the direction of the longitudinal axis 13. If this force is large enough, the valve spool 30 hits the locking screw 29, whereby the connection from the first to the second channel 21; 22 is maximally open. It is understood that the present slide valve 30 enables continuous adjustment, so that the relevant opening cross-sections are continuously adjustable, being approximately proportional to the current in the electrical coil. At least the corresponding relationship is monotonic.

In addition to the forces explained above, flow forces also act on the valve spool 30. The spool valve 40 should be designed so that, in total, no flow force acts on the valve spool 30, because then the control behavior of the entire hydraulic system is optimal.

2 shows an enlarged section of 1 in the area of the first and second webs 31; 32. The cutting plane of the 2 , which contains the longitudinal axis 13, forms a reference plane, which is characterized in that the first, second and third channels 21; 22; 23 are intersected by the reference plane. The reference side 14 is the side of the reference plane on which the first, second and third channels 21; 22; 23 are arranged, wherein said channels are arranged on the same side of the longitudinal axis 13. The first channel 21 can be continued in alignment on the side of the longitudinal axis 13 opposite the reference side 14, although this is preferably not the case for the second and third channels 22; 23.

A first measure for minimizing flow forces consists in making the first groove 41, which is arranged on the valve spool 30 between the first and second webs, wide enough that the first and second webs 31; 32 do not overlap the central first channel 21 in any position of the valve spool 30. The central channel 21 preferably opens directly into the spool bore 24.

It should first be noted that the flow forces acting radially to the longitudinal axis 13 are particularly problematic, as they press the valve spool 30 against the spool bore 24. The resulting frictional forces disrupt the adjustment of the valve spool 30 significantly more than the flow forces acting in the direction of the longitudinal axis 13, because the aforementioned friction causes hysteresis in the adjustment of the valve spool 30, which is particularly disruptive in the context of digital control.

The aforementioned radial flow forces are primarily determined by the pressure difference in the region of the first channel between the reference side 14 and the opposite side with respect to the longitudinal axis 13. These can be minimized by a wide first groove 41. Furthermore, the claimed width ensures that the flow in the region of the first and second orifices 11; 12 is minimally disturbed by the first channel 21 in all positions of the valve spool 30, so that it is largely rotationally symmetrical with respect to the longitudinal axis 13.

The second and third grooves 42; 43, which run annularly around the longitudinal axis 13 in the housing 20, ensure that the second and third channels 22; 23 also minimally disrupt the flow in the region of the first and second orifices 11; 12, respectively. The second and third channels 22; 23 do not open directly into the slide bore 24, but rather in sections into the second and third grooves 42; 43, respectively. The corresponding orifice opening is accordingly arranged at a distance from the first and second orifices 11; 12, respectively.

At the transition between the slide bore 24 and the second groove 42, a counter-control edge 25 is formed, which is provided with a chamfer 26. This, together with the sharp-edged control edge 35 on the first web 31, forms the adjustable first orifice 11. The second orifice 12 is formed in an analogous manner by a counter-control edge 25 between the slide bore 24 and the third groove 43 and a control edge 35 on the second web 32. The control edges 35 are formed by a first and a second end face 33; 34 on the first and second webs 31; 32, respectively, which point towards the first groove 41. Both the control can th 35 and the counter-control edges 25 run endlessly and preferably without interruption around the longitudinal axis 13

The aforementioned chamfers 26 are primarily due to the continuous adjustability of the first and second orifices 11; 12, so that their opening cross-section changes slowly when the valve slide 30 is displaced. For this purpose, chamfers that encircle the longitudinal axis 13 with a constant cross-sectional shape would be entirely sufficient. However, the applicant's investigations have shown that it is advantageous to slightly vary the shape of the chamfer 26, namely its length 27 and its depth 28, over the circumference of the longitudinal axis 13. The angle of inclination of the chamfer 26, in contrast, is preferably constant over the circumference of the longitudinal axis 13. By appropriately selecting the aforementioned variation, the radially acting flow forces can be noticeably reduced. The aforementioned variation is preferably determined experimentally by computer-aided simulation of the flow conditions, simulating various design cases. In the context of such simulations, it has been shown that it is advantageous if the depth 28 or the length 27 of the chamfer 26 is greatest in the region of the reference plane on the reference side 14. The course of the aforementioned dimensions 28; 27 over the circumference of the longitudinal axis 13 is preferably periodic, with two, three, or four periods over the entire circumference being preferred.

It is understood that the variation mentioned also influences the opening behavior of the first and second apertures 11; 12, respectively, whereby the fine control range is particularly influenced. In contrast to known fine control notches or grooves, such as those known from DE 10 2005 030 173 A1 However, unlike the known fine control notches or grooves, a chamfer 26 is present over the entire circumference of the valve spool 30, the size of which varies slightly. In the known fine control notches or grooves, a generally sharp-edged control edge is provided with recesses that influence the fine control range. The fine control notches are arranged on the valve spool because they are easier to manufacture there.

Also noteworthy are the two fourth grooves 44 in the housing 20, which extend adjacent to a second and a third groove 42; 43 in the housing 20 and extend around the longitudinal axis 13. It would be conceivable to combine the second groove 42 with the associated fourth groove 44, so that the second channel opens exclusively into this wider groove. However, the applicant's computer simulations have shown that the interfering contour formed by the second and associated fourth grooves 42; 44 in conjunction with the slide bore 24 therebetween influences the flow in such a way that the flow-induced radial forces on the valve slide 30 are minimized.

3 shows a perspective sectional view of the housing 20 of the slide valve, in which a counter control edge 25 with the chamfer 26 is visible. The sectional plane is perpendicular to the longitudinal axis (No. 13 in 1 ) aligned according to the section marking in 2 is arranged in the region of the third groove 43.

The chamfer has two first regions 73, in which the rough contour of the chamfer 26 is maintained and which are arranged diametrically opposite each other by 180°. Two second regions 74 are arranged offset by 90°, in which the rough contour of the chamfer is maintained according to the explanation of 4 was reworked. The chamfer 26 is longer and deeper there than in the first areas 73.

At the transition between the first and second regions 73; 74, a slight bend or edge is provided, as this simplifies the production of the chamfer 26. It is also conceivable to use a bend-free transition.

4 shows a rough schematic view of the grinding tool 70 for producing the chamfer 26 and the surrounding housing 20. Instead of the grinding tool 70, a similarly shaped milling tool can of course be used, whereby the high precision of grinding is advantageous. The grinding tool 70 is shown in its machining position relative to the longitudinal axis 13. Radially to the longitudinal axis 13, it is shown shortly before the start of material removal. 4 Accordingly, the rough contour 72 of the chamfer 26 is visible. This is arranged parallel to a circular cone-shaped machining contour 75 on the grinding tool 70. The machining contour 75 is longer in the direction of the longitudinal axis 13 than the finished chamfer.

The grinding tool is rotationally symmetrical with respect to its rotational axis 71. When inserting the grinding tool 70 into the slide bore 24, the rotational axis 71 coincides at least approximately with the longitudinal axis 13 so that the grinding tool does not damage the slide bore 24. The largest diameter of the grinding tool 70 is smaller than the diameter of the slide bore. The corresponding diameter difference is preferably small so that the grinding tool 70 is as rigid as possible.

After the 4 shown position of the grinding tool 70 in the direction of the longitudinal axis 13 is reached, the grinding tool 70 moved radially to the longitudinal axis 13 while rotating rapidly. The radial infeed depth is selected so that the desired material removal is achieved. It is conceivable to design the grinding tool so that the desired material removal is achieved with a purely radial infeed. However, it has proven advantageous to carry out an infeed in the circumferential direction with respect to the longitudinal axis 13 after the radial infeed. The contour of the chamfer 26 achieved in this way is more aerodynamic. The infeed in the circumferential direction can, for example, be 20°, with 360° corresponding to the entire circumference of the chamfer 26. By varying the infeed in the circumferential direction, the radially acting flow forces can be easily minimized without any changes to the grinding tool 70 being necessary.

Reference symbol

10

slide valve

11

first aperture

12

second aperture

13

Longitudinal axis

14

Reference page

15

Actuating magnet

16

Adjusting spring

20

Housing

21

first channel

22

second channel

23

third channel

24

Slide bore

25

Counter-control edge

26

chamfer

27

Length of the bevel

28

Depth of the chamfer

29

Locking screw

30

valve spool

31

first bridge

32

second bridge

33

first frontal surface

34

second frontal surface

35

Control edge

36

Auxiliary bridge

41

first groove

42

second groove

43

third groove

44

fourth groove

50

hydraulic system

51

Hydromachine

52

Actuating cylinder

53

Pressure fluid source

54

Pressure fluid sink

55

tank

56

Controller

57

pressure sensor

58

Low pressure connection

59

High-pressure connection

60

Pole tube

61

electric coil

62

anchor

63

consumer

64

Auxiliary actuating cylinder

65

drive motor

66

Pressure relief channel in the housing

67

Pressure relief channel in the valve spool

68

push rod

70

Grinding tool

71

axis of rotation

72

Raw contour of the bevel

73

first area in which the raw contour of the bevel is preserved

74

second area in which the chamfer is reworked starting from the raw contour

75

Machining contour on the grinding tool

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2021 207 837 A1 [0002, 0003]
• DE 10 2019 219 451 A1 [0002]
• DE 10 2020 208 933 A1 [0003]
• DE 10 2021 207 650 A1 [0003]
• DE 10 2022 201 755 A1 [0003]
• DE 10 2005 030 173 A1 [0010, 0043]

Claims (14)

Slide valve (10) with a housing (20) and a valve slide (30), wherein the housing (20) has a slide bore (24) which is substantially circular-cylindrical with respect to a longitudinal axis (11), wherein the valve slide (30) is received in the slide bore (24) so as to be linearly movable along the longitudinal axis (11), wherein the valve slide (30) has a first and a second web (31; 32), which each run annularly around the longitudinal axis (13), wherein they are each sealingly adapted to the slide bore (24), wherein the first and the second web (31; 32) are delimited from one another by a first groove (41) on the valve slide (30), wherein a first, a second and a third channel (21; 22; 23) are provided in the housing (20), wherein the first channel (21) opens into the slide bore (24) such that it Fluid exchange connection with the first groove (41), characterized in that the first groove (41) is designed so wide in the direction of the longitudinal axis (13) that the first channel (21) is arranged in the region of the first groove (41) in every possible position of the valve slide (30), so that it is not covered by the first and second webs (31; 32). Slide valve (10) after Claim 1 , wherein a second groove (52) is arranged in the housing (20) adjacent to the first web (31), wherein the second groove (52) runs annularly around the longitudinal axis (13), wherein it forms a continuously adjustable first aperture (11) with a first end face (33) of the first web (31) facing the first groove (41), wherein the second channel (22) opens into the second groove (42) at least in sections. Slide valve (10) according to one of the preceding claims, wherein a third groove (43) is arranged in the housing (20) adjacent to the second web (32), wherein the third groove (43) runs annularly around the longitudinal axis (11), wherein it forms a continuously adjustable second aperture (12) with a second end face (34) of the second web (32) facing the first groove (41), wherein the third channel (23) opens into the third groove (43) at least in sections. Slide valve (10) after Claim 2 or 3 , wherein a control edge (35) assigned to the first and/or the second diaphragm (11; 12) on the first or second web (31; 32) is formed over its entire circumference with a constant, substantially sharp-edged cross-sectional shape. Slide valve (10) according to one of the Claims 2 until 4 , wherein a counter-control edge (25) assigned to the first and/or the second orifice (12), which in each case forms a transition from the slide bore (24) to the second or the third groove (42; 43), is in each case designed as a chamfer (26) whose angle of inclination to the longitudinal axis (13) is between 20° and 40°. Slide valve (10) after Claim 5 , wherein a length (27) of the chamfer (26), which is measured in the direction of the longitudinal axis (13), changes along a circumference of the chamfer (26) with respect to the longitudinal axis (13). Slide valve (10) after Claim 5 or 6 , wherein a depth (28) of the chamfer (26), which is measured radially to the longitudinal axis (13), changes along a circumference of the chamfer (26) with respect to the longitudinal axis (13). Slide valve (10) after Claim 6 or 7 , wherein the first, the second and the third channel (21; 22; 23) are arranged substantially in a common reference plane, the length (27) and/or the depth (28) of the chamfer (26) being greatest in the region of the reference plane. Slide valve (10) after Claim 8 , wherein a reference side (14) is arranged on the side of the longitudinal axis (11) on which the first, second and third channels (21; 22; 23) are arranged, wherein the length (27) and/or the depth (28) of the chamfer (26) is greatest on the reference side (14). Slide valve (10) according to one of the Claims 2 until 9 , wherein the second and/or the third groove (42; 43) is each assigned a separate fourth groove (44) in the housing (20), wherein the fourth groove (44) is arranged further away from the first channel (21) than the respective second or third groove (42; 43), so that the slide bore (24) is present in sections between the fourth groove (44) and the associated second or third groove (42; 43), wherein the second or third channel (22; 23) also opens into the respective fourth groove (44). Method for producing a slide valve (10) according to one of the Claims 6 until 10 , as far as these are based on Claim 6 or 7 are referred back, wherein a blank of the housing (20) is provided, in which a raw contour (72) of the chamfer (26) is formed rotationally symmetrically with respect to the longitudinal axis (13), wherein subsequently, by means of a milling or grinding tool which is introduced into the slide bore (24), further material is removed from the raw contour (72) of the chamfer (26) at two or more locations which are spaced apart from one another in the circumferential direction with respect to the longitudinal axis (13), in order to obtain a final contour of the chamfer (26). Procedure according to Claim 11 , wherein the milling or grinding tool (70) is fed exclusively radially to the longitudinal axis (13) during the said removal of further material. Procedure according to Claim 11 , wherein the milling or grinding tool (70) is first fed radially to the longitudinal axis (13) during the said removal of further material, and is then fed in the circumferential direction with respect to the longitudinal axis (13). A hydraulic machine (51) whose displacement volume is adjustable by means of an actuating cylinder (52), the hydraulic machine (51) comprising a slide valve (10) according to one of the preceding claims, the first channel (21) being connected to the actuating cylinder (52), the second channel (22) being connected to a pressurized fluid source (53), and the third channel (23) being connected to a pressurized fluid sink (54), the slide valve (10) comprising an actuating magnet (15) and an actuating spring (16), a position of the valve slide (30) being defined exclusively by the force equilibrium between the force of the actuating magnet (15), the force of the actuating spring (16), and the forces caused by the flow of the pressurized fluid between the first, second, and third channels (21; 22; 23), a controller (56) being provided, the actuating variable of which is an electric current in the actuating magnet (15).