Valve assembly and electro-hydraulic valve

Abstract

The invention relates to a valve unit (1) comprising a valve slider (2) and a valve sleeve (3) in which the valve slider (2) is moveably guided, wherein the valve slider (2) can be moved along the valve sleeve (3) in order to variably adjust a fluid flow through the valve unit (1), wherein the valve slider (2) and valve sleeve (3) are each formed from a composite material including a base polymer and reinforcing fibres, wherein the base polymers of the valve slider (2) and the valve sleeve (3) are the same, wherein the valve slider (2) has at least one contact surface (4) with which the valve slider (2) is in contact with the valve sleeve (3), and wherein the contact surface (4) is machined.

Description

[0001] Valve arrangement and electro-hydraulic valve

[0002] Description

[0003] The invention relates to a valve unit. Furthermore, the invention relates to an electrohydraulic valve with a valve unit.

[0004] Valve units for hydraulic valves are known from the prior art. These typically comprise a valve sleeve and a valve spool guided within it. For example, DE 10 2014 012 306 A1, DE 10 2005 051 177 A1, and DE 101 50 030 A1 show various valves.

[0005] When the valve spool is moved within the valve sleeve as intended, sliding friction occurs. To minimize wear and achieve optimal valve performance, different materials are typically used for the valve spool and valve sleeve. For example, DE 10 2018 115 914 A1 discloses an electrohydraulic valve comprising a valve spool made of a polyetheretherketone-based composite material and a valve sleeve made of a polyphenylene sulfide-based composite material.

[0006] The object of the invention is to provide a valve assembly that is simple and cost-effective to manufacture and functions reliably and durably. This object is achieved by the features of the independent claim. The subclaims contain preferred developments of the invention.

[0007] The solution is thus provided by a valve unit with a valve spool and a valve sleeve in which the valve spool is movably guided. The valve spool can be moved along the valve sleeve to adjust the fluid flow through the valve unit. This makes it possible, in particular, to provide and block different fluid paths through the valve unit by varying the positions of the valve spool within the valve sleeve. The valve unit is particularly preferably a multi-way valve and / or designed for use as a proportional valve.

[0008] The valve spool and the valve sleeve are each formed from a composite material comprising a base polymer and reinforcing fibers. The base polymer is, in particular, an amorphous or semi-crystalline and particularly preferably water-repellent and / or media-tight, high-temperature-resistant thermoplastic. A water-repellent property is understood, in particular, to mean that, at the highest operating temperature, water absorption amounts to a maximum of 1% of the weight of the valve spool and / or the valve sleeve. Furthermore, the composite material advantageously exhibits good dimensional accuracy after primary forming and / or forming processing.

[0009] If the valve spool is moved within the valve sleeve, sliding friction occurs. In this case, it is particularly important that the valve spool fits tightly against the valve sleeve in order to ensure that the valve unit is leak-tight. This means that the fit between the valve spool and valve sleeve prevents fluid from accidentally passing between the valve spool and valve sleeve or that such leakage is minimized. In order to minimize wear resulting from sliding friction, it is known from the prior art to use different base polymers for the sliding partners. However, the invention provides that, in contrast to this established teaching, the base polymers of the valve spool and the valve sleeve are of the same type, in particular identical. By "similar" is meant in particular that the base polymers have the same repeating groups.Additionally, the valve spool is provided with at least one contact surface with which the valve spool rests against the valve sleeve, with the contact surface being machined. This minimizes wear despite the similar, particularly identical, base polymers. This minimizes fluid leakage between the valve spool and the valve sleeve at the contact surface, and also minimizes friction between the valve spool and the valve sleeve, thus reducing wear.

[0010] When manufacturing a valve sleeve from a composite material as described above, an edge layer remains in particular in which no or only a few reinforcing fibers are present and thus predominantly the base polymer, with any additives present. By machining the contact surface of the valve spool, however, such edge layers are removed and the reinforcing fibers are exposed on the surface, i.e. at the contact surface. The reinforcing fibers, particularly preferably in the case of carbon fibers, offer optimal sliding friction properties. It has surprisingly been shown that even with a similar, in particular identical, base polymer of the sliding partners, optimal sliding friction properties can be achieved by the reinforcing fibers exposed by machining, so that wear on the valve unit is minimized. This means that a long-lasting valve unit can be manufactured simply and cost-effectively.

[0011] It is particularly advantageous to have an operating medium inside the valve sleeve during operation of the valve unit. This operating medium further reduces wear, as the fluid friction minimizes the abrasion between the valve spool and the valve sleeve.

[0012] Preferably, the valve spool and / or the valve sleeve is an injection-molded part. By producing the valve spool and / or valve sleeve by injection molding, the valve spool and / or valve sleeve can be manufactured cost-effectively. At the same time, the required shapes and contours can be produced easily and with little effort, whereby a high degree of dimensional accuracy of the valve spool and / or valve sleeve is achieved. In injection-molded production, the reinforcing fibers are not present or are present only in small quantities in the outermost edge layers of the injection-molded composite material. In particular, an injection-molded skin is created in which the reinforcing fibers are not present or are present only in minimal quantities. Preferably, in the valve sleeve, the reinforcing fibers are therefore not present on the surface.The valve spool is preferably machined after injection molding, with the machining being carried out in particular only in partial areas of the valve spool so that the character of the injection molded part is retained outside the machined partial areas.

[0013] In an advantageous embodiment of the invention, the base polymer is polyphenylene sulfide. In particular, polyphenylene sulfide exhibits optimal media resistance and is therefore ideally suited for use in the valve spool and / or the valve sleeve. Furthermore, optimal dimensional accuracy is achieved when the valve spool and / or the valve sleeve are manufactured by injection molding.

[0014] The reinforcing fibers are primarily carbon fibers and / or glass fibers. These offer optimal force transferability while also being lightweight. Thus, the reinforcing fibers can be advantageously used to reinforce the composite material. The composite material therefore exhibits optimized weight and strength.

[0015] It is particularly advantageous that the reinforcing fibers of the valve spool be carbon fibers and / or the reinforcing fibers of the valve sleeve be glass fibers. The valve spool is, as previously described, machined, in particular. As a result, the reinforcing fibers, which are carbon fibers, lie directly on the contact surface of the valve spool. Carbon has ideal sliding friction properties. Thus, despite the same base polymer, no increased wear is to be expected when the valve spool slides against the valve sleeve. Rather, wear is minimized by the carbon in the reinforcing fibers. The use of glass fibers increases the weld line strength, which is particularly advantageous for the valve sleeve. The glass fiber-reinforced base polymer allows for a higher permissible elongation than with a carbon fiber-reinforced base polymer, which in particular increases the weld line strength.

[0016] The composite material of the valve spool and / or the valve sleeve preferably comprises, in addition to the base polymer and the reinforcing fibers, polytetrafluoroethylene. The polytetrafluoroethylene serves, in particular, as a filler in the composite material. This improves the water-repellency and / or media resistance and / or friction properties of the composite material.

[0017] The valve sleeve preferably has a mating contact surface that rests against the contact surface of the valve spool. Unlike the contact surface, the mating contact surface is not machined. Thus, a characteristic property of injection molding is particularly advantageously present at the mating contact surfaces. The absence of machining prevents the reinforcing fibers of the valve sleeve from coming into contact with a surface of the valve sleeve, in particular a surface of the mating contact surface. Thus, the base polymer is always present on the surface of the valve sleeve, in particular the mating contact surface.

[0018] A diametrical clearance between the valve spool and the valve sleeve is in particular less than 1.5% of the diameter of the valve spool. The diametrical clearance is preferably less than 1.0% of the diameter of the valve spool. Alternatively or additionally, the diametrical clearance is at least 0.1%, preferably at least 0.2%. This diametrical clearance is present in particular at the contact surface where the valve spool rests against the valve sleeve. The diameter of the valve spool therefore corresponds to the diameter at the contact surface. Such diametrical clearances ensure, on the one hand, sufficient tightness between the valve spool and the valve sleeve, and, on the other hand, optimal mobility of the valve spool in the valve sleeve.Diameter clearances as described above can be achieved easily and with little effort, in particular by designing the valve spool and / or valve sleeve as an injection-molded part and machining the contact surface of the valve spool.

[0019] Furthermore, it is preferably provided that the composite material of the valve sleeve has a volume fraction of between 30% and 50% reinforcing fibers. In particular, said volume fraction is between 35% and 45%, particularly preferably between 38% and 42%. Alternatively or additionally, it is preferably provided that the composite material of the valve spool has a volume fraction of between 20% and 40% reinforcing fibers. In particular, said volume fraction is between 25% and 35%, particularly preferably between 28% and 32%. Such a quantity of reinforcing fibers allows for an ideal possibility of absorbing tensile forces and thus achieving a long service life of the valve unit.

[0020] The invention also relates to an electrohydraulic valve. The valve comprises an electromagnet and a valve unit as described above. An armature of the electromagnet is coupled to the valve spool of the valve unit in order to displace the valve spool within the valve sleeve in at least one direction. Preferably, an elastic return spring is provided, which acts on the valve spool and / or the armature, whereby the valve spool can be returned to an initial position. The electrohydraulic valve is particularly advantageously used for switching hydraulic oil flows, whereby the hydraulic oil additionally exerts a friction-reducing effect between the valve spool and the valve sleeve.

[0021] Further details, advantages, and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows:

[0022] Fig. 1 is a schematic view of an electro-hydraulic valve according to an embodiment of the invention, and

[0023] Fig. 2 is a schematic view of a valve unit according to an embodiment of the invention.

[0024] Figure 1 schematically shows an electrohydraulic valve 6 according to an embodiment of the invention. The electrohydraulic valve 6 is, in particular, a hydraulic valve and has an electromagnet 7 with an armature 8 as the drive for the valve 6.

[0025] Furthermore, the electrohydraulic valve 6 has a valve unit 1. A valve unit 1 according to a further embodiment is also shown in Figure 2. The valve unit 1 has a valve spool 2 and a valve sleeve 3. The valve units 1 in Figures 1 and 2 merely enable different valve circuits; however, the basic structure and the components used are identical, which is why Figures 1 and 2 are described together below. The valve spool 2 is guided in the valve sleeve 3 and can be moved along a longitudinal axis 100 of the valve sleeve 3 to adjust different fluid flows.

[0026] An outer side of the valve sleeve 3 can be placed against a wall 10, whereby the valve sleeve 3 defines various inlets and / or outlets for fluid. By appropriately arranging the valve spool 2 in the valve sleeve 3, different fluid paths through the valve unit 1 can be opened or blocked. The valve spool 2 is coupled to the armature 8, whereby the armature 8 can displace the valve spool 2 in at least one direction along the longitudinal axis 100. The coupling is achieved, for example, by an armature rod 8a. The electromagnet 7 thus serves to drive the valve spool 2 and thereby to adjust the fluid flow. The valve spool 2 is preferably also loaded by a return spring 9, whereby a restoring force acts on the valve spool 2 and the armature 8 when a displacement has occurred by the armature 8.Thus, the valve spool 2 is always in the same rest state when the electromagnet 7 is de-energized and only the restoring force of the return spring 9 acts on the valve spool 2.

[0027] During normal operation of the valve 6 and the valve unit 1, the valve spool 2 slides along the valve sleeve 3. The valve spool 2 has a plurality of contact surfaces 4 with which the valve spool 2 rests against the valve sleeve 3. In particular, the contact surfaces 4 of the valve spool 2 rest against a mating contact surface 5 of the valve sleeve 3, wherein the mating contact surface 5 corresponds in particular to an inner surface of the valve sleeve 3. Fluid leakage between the contact surfaces 4 and the mating contact surface 5 is minimized, thus enabling reliable switching of the valve unit 1 by moving the valve spool 2.

[0028] The minimization of leakage and the possibility of displacement of the valve spool 2 is achieved in particular by a diametrical clearance between the valve spool 2 and the valve sleeve 3 at the contact surfaces 4, which is less than 1.5%, preferably less than 1.0%, and / or at least 0.1%, preferably at least 0.2% of the diameter of the valve spool 2 at the contact surfaces 4. In order to achieve such diametrical clearances and to manufacture the valve unit 1 simply and cost-effectively, the valve spool 2 and the valve sleeve 3 are injection-molded parts made from a composite material. The valve spool 2 is made from a composite material with a base polymer and carbon fibers as reinforcing fibers. The valve sleeve 3 is made from a composite material with a base polymer and glass fibers as reinforcing fibers. The base polymer for both the valve spool 2 and the valve sleeve 3 is polyphenylene sulfide.

[0029] The valve spool 2 is machined at the contact surfaces 4. This results in the carbon fibers of the composite material of the valve spool 2 being exposed at the contact surface 4. The mating contact surface 5, on the other hand, is not machined. This leaves an injection-molded skin, i.e. the base polymer is predominantly or exclusively present at the mating contact surface 5. Due to the exposed carbon fibers at the contact surface 4, optimal sliding friction is present despite the sliding partners, valve spool 2 and valve sleeve 3, being of the same type, in particular identical, base polymer. This friction is optimized by the reinforcing fibers, in particular the carbon of the carbon fibers. This allows the valve spool 2 and valve sleeve 3 to be manufactured simply and cost-effectively, while wear on the valve unit 1 caused by sliding friction is minimized.Wear is further minimized by the operating medium within the valve unit 1, which is primarily hydraulic oil. This operating medium creates fluid friction, which further reduces wear.

[0030] The valve sleeve 3 preferably comprises glass fibers as reinforcing fibers, which results in higher weld line strength. This is made possible by the fact that the glass fiber-reinforced composite materials allow a higher permissible elongation than is achievable with other fibers as reinforcement.

[0031] Preferably, the composite material of the valve sleeve 3 has a volume fraction of between 30% and 50%, preferably between 35% and 45%, particularly preferably between 38% and 42%, of reinforcing fibers, and the composite material of the valve spool 2 has a volume fraction of between 20% and 40%, preferably between 25% and 35%, particularly preferably between 28% and 32%, of reinforcing fibers. Thus, force absorption by the reinforcing fibers within the composite material is optimized. The composite material is thus ideally suited for use in valve units 1.

[0032] The composite material of the valve spool 2 and / or the valve sleeve 3 preferably also contains polytetrafluoroethylene as a filler. The composite material therefore achieves optimal media tightness, a friction-optimized surface, and water-repellent properties.

[0033] In addition to the above written description of the invention, reference is hereby explicitly made to the drawings of the invention in Figs. 1 and 2 for its supplementary disclosure. List of reference symbols

[0034] 1 valve unit

[0035] 2 valve slides

[0036] 3 Valve sleeve 4 Contact surface

[0037] 5 Counter contact surface

[0038] 6 electro-hydraulic valve

[0039] 7 Electromagnet

[0040] 8 anchor 8a anchor rod

[0041] 9 Return spring

[0042] 10 Wall

[0043] 100 Longitudinal axis

Claims

Claims 1. Valve unit (1) comprising . a valve slide (2), and . a valve sleeve (3) in which the valve slide (2) is movably guided, wherein the valve slide (2) is displaceable along the valve sleeve (3) in order to differently adjust a fluid flow through the valve unit (1), wherein the valve slide (2) and valve sleeve (3) are each formed from a composite material comprising a base polymer and reinforcing fibers, wherein the base polymers of the valve slide (2) and the valve sleeve (3) are of the same type, wherein the valve slide (2) has at least one contact surface (4) with which the valve slide (2) rests against the valve sleeve (3), and wherein the contact surface (4) is machined.

2. Valve unit (1) according to claim 1, characterized in that the valve slide (2) and / or the valve sleeve (3) is an injection-molded part.

3. Valve unit (1) according to one of the preceding claims, characterized in that the base polymer is polyphenylene sulfide.

4. Valve unit (1) according to one of the preceding claims, characterized in that the reinforcing fibers are carbon fibers and / or glass fibers.

5. Valve unit (1) according to one of the preceding claims, characterized in that the reinforcing fibers of the valve slide (2) are carbon fibers and / or the reinforcing fibers of the valve sleeve (3) are glass fibers.

6. Valve unit (1) according to one of the preceding claims, characterized in that the composite material of the valve slide (2) and / or the valve sleeve (3) comprises polytetrafluoroethylene.

7. Valve unit (1) according to one of the preceding claims, characterized in that the valve sleeve (3) has a counter-contact surface (5) which bears against the contact surface (4) of the valve slide (2), wherein the counter-contact surface (5) is not machined.

8. Valve unit (1) according to one of the preceding claims, characterized in that a diameter clearance between the valve slide (2) and the valve sleeve (3) is less than 1.5%, preferably less than 1.0%, and / or at least 0.1%, preferably at least 0.2%, of the diameter of the valve slide (2). Valve unit (1) according to one of the preceding claims, characterized in that the composite material of the valve sleeve (3) has a volume fraction of between 30% and 50%, preferably between 35% and 45%, particularly preferably between 38% and 42%, and / or that the composite material of the valve slide (2) has a volume fraction of between 20% and 40%, preferably between 25% and 35%, particularly preferably between 28% and 32%, of reinforcing fibers. Electrohydraulic valve (6) comprising an electromagnet (7) and a valve unit (1) according to one of the preceding claims, wherein an armature (8) of the electromagnet (7) is coupled to the valve spool (2) of the valve unit (1) in order to displace the valve spool (2) within the valve sleeve (3) in at least one direction.

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