Valve assembly and electro-hydraulic valve

Abstract

The invention relates to a valve unit (1) having a valve core (2) and a valve housing (3) in which the valve core (2) is movably guided, the valve core (2) being displaceable along the valve housing (3) in order to set a fluid flow through the valve unit (1) differently, the valve core (2) and the valve housing (3) being each formed from a composite material having a base polymer and reinforcing fibers, wherein the base polymers of the valve core (2) and the valve sleeve (3) are similar, the valve core (2) has at least one contact surface (4) with which the valve core (2) rests against the valve sleeve (3), and the contact surface (4) is cut.

Description

[0001] The present invention relates to a valve unit. The present invention also relates to an electrohydraulic valve having the valve unit.

[0002] Valve units for hydraulic valves are known from the prior art. These valve units usually have a valve sleeve and a valve core guided therein. For example, DE 10 2014 012 306 A1, DE 10 2005 051 177 A1 or DE 101 50 030 A1 show different valves.

[0003] If the valve core moves as intended in the valve sleeve, sliding friction occurs. In order to minimize wear and achieve optimal valve behavior, different materials are usually used for the valve core and the valve sleeve. Therefore, DE 10 2018 115 914 A1 discloses an electrohydraulic valve having a valve core made of a composite material based on polyetheretherketone and a valve sleeve made of a composite material based on polyphenylene sulfide.

[0004] The object of the invention is to provide a valve assembly which can be manufactured easily and cost-effectively and functions reliably and durably. This object is achieved by the features of the independent claim. The contents of the dependent claims are preferred developments of the invention.

[0005] The solution is therefore achieved by a valve unit having a valve core and a valve sleeve, wherein the valve core is guided in a movable manner in the valve sleeve. The valve core can be displaced along the valve sleeve in order to set the fluid flow through the valve unit differently. Thus, in particular different fluid paths through the valve unit can be provided and blocked by different positions of the valve core in the valve sleeve. The valve unit is particularly preferably a multi-way valve and / or is designed to be used as a proportional valve.

[0006] The valve core and the valve sleeve are each formed from a composite material having a base polymer and reinforcing fibers. The base polymer is in particular an amorphous or partially crystalline and particularly preferably a water-repellent and / or medium-tight, high-temperature-resistant thermoplastic. The water-repellent property can be understood in particular as: at the highest operating temperature, a water absorption of at most 1% of the weight of the valve core and / or valve sleeve. In addition, the composite material advantageously has good shape accuracy after the initial shaping process and / or reshaping process.

[0007] If the valve core moves in the valve sleeve, sliding friction is generated. In particular, it is necessary to consider that the valve core is closely attached to the valve sleeve to achieve the sealing of the valve unit. This means that the cooperation between the valve core and the valve sleeve prevents the fluid from passing through the valve core and the valve sleeve unexpectedly, or such leakage is minimized. In order to minimize the wear caused by sliding friction, it is known from the prior art that different base polymers are used for sliding pairs. However, according to the present invention, compared with the established teaching content, the base polymers of the valve core and the valve sleeve are similar, especially the same. The term "similar" can be understood in particular as: the base polymer has the same, repeated groups. In addition, it is proposed that the valve core has at least one contact surface, and the valve core is attached to the valve sleeve with the contact surface, wherein the contact surface is cut. Thus, even if the base polymers are similar, especially the same, wear can still be minimized. Therefore, it is achieved that on the one hand, the fluid leakage between the valve core and the valve sleeve at the contact surface is minimized, and on the other hand, the friction between the valve core and the valve sleeve is minimized and thus the wear is minimized.

[0008] When the valve sleeve is manufactured from a composite material as described above, in particular, an edge layer is retained, in which no or only very few reinforcing fibers are present and thus mainly the base polymer (and any additives present) are present. Such an edge layer is removed by machining the contact surface of the valve core and the reinforcing fibers are opened at the surface (i.e. at the contact surface). The reinforcing fibers (particularly preferably in the case of carbon fibers) provide the best sliding friction properties. It has surprisingly been shown that even in the case of similar, especially identical base polymers of the sliding pairs, the best sliding friction properties can be achieved by means of the reinforcing fibers exposed by machining, thereby minimizing the wear of the valve unit. As a result, a durable valve unit can be manufactured easily and cost-effectively.

[0009] It is particularly advantageous if a working medium is present in the valve sleeve during operation of the valve unit. The working medium reduces wear further, since the fluid friction minimizes wear between the valve core and the valve sleeve.

[0010] It is preferably proposed that the valve core and / or the valve sleeve is an injection molded part. By manufacturing the valve core and / or the valve sleeve by means of injection molding, the valve core and / or the valve sleeve can be produced cost-effectively. At the same time, the required shape and contour can be easily and inexpensively manufactured, wherein in particular there is a high shape accuracy of the valve core and / or the valve sleeve. When injection molding is carried out, the reinforcing fibers are not present or are only present in small quantities in the outermost edge layer of the injection molded composite material. In particular, there is such an injection molded surface layer in which the reinforcing fibers are not present or are only minimally present. Preferably, in the valve sleeve, the reinforcing fibers are therefore not present on the surface. The valve core is preferably subjected to cutting processing after injection molding, wherein the cutting processing is particularly only carried out in multiple sub-areas of the valve core, so that the characteristics of the injection molded part are retained outside the processed sub-areas.

[0011] In an advantageous embodiment of the invention, the base polymer is polyphenylene sulfide. In particular, polyphenylene sulfide has the best media resistance and is therefore optimally suitable for the valve core and / or valve sleeve. In addition, when the valve core and / or valve sleeve are produced by injection molding, the best shape accuracy is achieved.

[0012] The reinforcing fibers are in particular carbon fibers and / or glass fibers. The reinforcing fibers have an optimal force transmission capability on the one hand and a low weight on the other hand. Therefore, the reinforcing fibers can be advantageously used to reinforce the connecting material. Therefore, the composite material has an optimized weight and an optimized strength.

[0013] It is particularly advantageous if the reinforcing fibers of the valve core are carbon fibers and / or the reinforcing fibers of the valve sleeve are glass fibers. As described above, the valve core is in particular machined. As a result, the reinforcing fibers (carbon fibers) are directly on the contact surface of the valve core. Carbon has ideal sliding friction properties. Therefore, even with the same base polymer, no increase in wear can be expected when the valve core slides on the valve sleeve. On the contrary, wear is minimized by the carbon reinforcing fibers. By using glass fibers, the joint strength is increased, which is particularly advantageous for the valve sleeve. The permissible elongation allowed for the base polymer reinforced with glass fibers is higher than the elongation in the case of the base polymer reinforced with carbon fibers, whereby in particular the joint strength is increased.

[0014] The composite material of the valve core and / or valve sleeve preferably comprises polytetrafluoroethylene in addition to the base polymer and the reinforcing fibers. Polytetrafluoroethylene is used in particular as a filler for the composite material. This improves the water repellency and / or media resistance and / or friction properties of the composite material.

[0015] The valve sleeve preferably has a counter-contact surface which bears against the contact surface of the valve core. Unlike the contact surface, the counter-contact surface is not machined. Therefore, the characteristic properties of injection molding are particularly advantageously present at the counter-contact surface. Due to the lack of machining, it is especially avoided that the reinforcing fibers of the valve sleeve reach the surface of the valve sleeve, especially the surface of the counter-contact surface. Therefore, the base polymer is always present on the surface of the valve sleeve, especially the counter-contact surface.

[0016] The diametrical clearance between the valve core and the valve sleeve is, in particular, less than 1.5% of the diameter of the valve core. The diametrical clearance is preferably less than 1.0% of the diameter of the valve core. Alternatively or additionally, the diametrical clearance is at least 0.1%, preferably at least 0.2%. The diametrical clearance is particularly present at the contact surface of the valve core against the valve sleeve. Therefore, the diameter of the valve core corresponds to the diameter at the contact surface. By means of such a diametrical clearance, on the one hand, sufficient sealing is provided between the valve core and the valve sleeve, and on the other hand, the optimal mobility of the valve core in the valve sleeve is ensured. The diametrical clearance as described above can be easily and cost-effectively realized, in particular by designing the valve core and / or the valve sleeve as an injection molded part and cutting the contact surface of the valve core.

[0017] It is furthermore preferred that the composite material of the valve sleeve has a volume ratio of reinforcing fibers of between 30% and 50%. In particular, the volume ratio is between 35% and 45%, particularly preferably between 38% and 42%. Alternatively or additionally, it is preferred that the composite material of the valve core has a volume ratio of reinforcing fibers of between 20% and 40%. In particular, the volume ratio is between 25% and 35%, particularly preferably between 28% and 32%. Such an amount of reinforcing fibers allows an ideal possibility to absorb tensile forces and thus achieve a long service life of the valve unit.

[0018] The invention also relates to an electrohydraulic valve. The valve comprises an electromagnet and a valve unit as described above. The armature of the electromagnet is coupled to a valve core of the valve unit so that the valve core is displaced in at least one direction within a valve sleeve. Preferably, an elastic return spring is provided, which acts on the valve core and / or the armature, whereby the valve core can be returned to an initial position. The electrohydraulic valve is particularly useful for switching a hydraulic oil flow, wherein the hydraulic oil additionally achieves a friction-reducing effect between the valve core and the valve sleeve.

[0019] Further details, advantages and features of the invention will be apparent from the following description of exemplary embodiments with the aid of the accompanying drawings. In the drawings:

[0020] Figure 1 A schematic diagram showing an electrohydraulic valve according to an embodiment of the present invention, and

[0021] Figure 2 A schematic view of a valve unit according to an embodiment of the present invention is shown.

[0022] Figure 1 An electrohydraulic valve 6 according to an exemplary embodiment of the present invention is schematically shown. The electrohydraulic valve 6 is, in particular, a hydraulic valve and has an electromagnet 7 with an armature 8 as a drive for the valve 6 .

[0023] Furthermore, the electrohydraulic valve 6 has a valve unit 1. Figure 2 2 shows a valve unit 1 according to another embodiment. The valve unit 1 comprises a valve core 2 and a valve sleeve 3. Figure 1 and Figure 2 The valve unit 1 in the embodiment can only realize other valve circuits, but the basic structure and the components used are the same, so they are described together below. Figure 1 and Figure 2 The valve core 2 is guided in the valve housing 3 and can be displaced along the longitudinal axis 100 of the valve housing 3 in order to set different fluid flows.

[0024] The outer side of the valve sleeve 3 can be against the wall 10, whereby the valve sleeve 3 defines different inlets and / or outlets for the fluid. By correspondingly arranging the valve core 2 in the valve sleeve 3, different fluid paths through the valve unit 1 can be released or blocked.

[0025] The valve core 2 is coupled to an armature 8, whereby the armature 8 can displace the valve core 2 in at least one direction along the longitudinal axis 100. The coupling is carried out, for example, via the armature rod 8a. Thus, the electromagnet 7 serves as a drive for the valve core 2 and thus for setting the fluid flow. The valve core 2 is preferably also loaded by a return spring 9, whereby a return force acts on the valve core 2 and the armature 8 when displaced by the armature 8. Thus, the valve core 2 is always in the same resting state when the electromagnet 7 is de-energized and only the return force of the return spring 9 acts on the valve core 2.

[0026] In normal operation of the valve 6 and the valve unit 1, the valve core 2 slides along the valve sleeve 3. The valve core 2 has a plurality of contact surfaces 4, with which the valve core 2 abuts against the valve sleeve 3. In particular, the contact surfaces 4 of the valve core 2 abut against the matching contact surfaces 5 of the valve sleeve 3, wherein the matching contact surfaces 5 correspond in particular to the inner surface of the valve sleeve 3. Leakage of fluid between the contact surfaces 4 and the matching contact surfaces 5 is minimized, so that the valve unit 1 can be reliably switched by displacing the valve core 2.

[0027] The minimization of leakage and the possibility of displacement of the valve core 2 are achieved in particular by a diametrical gap between the valve core 2 and the valve sleeve 3 at the contact surface 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 core 2 at the contact surface 4. In order to achieve such a diametrical gap and to manufacture the valve unit 1 easily and cost-effectively, the valve core 2 and the valve sleeve 3 are injection molded parts made of composite materials. The valve core 2 is made of a composite material having a base polymer and carbon fibers as reinforcing fibers. The valve sleeve 3 is made of a composite material having a base polymer and glass fibers as reinforcing fibers. In both the valve core 2 and the valve sleeve 3, the base polymer is polyphenylene sulfide.

[0028] The valve core 2 is machined at the contact surface 4. This leaves the carbon fibers of the composite material of the valve core 2 open at the contact surface 4. The mating contact surface 5 is not machined. Therefore, the injection molded surface is retained, i.e., the base polymer is mainly or exclusively present on the mating contact surface 5. By exposing the carbon fibers on the contact surface 4, even if the base polymers of the sliding pair "valve core 2 and valve sleeve 3" are similar, especially the same, there is still an optimal sliding friction, which is optimized by the carbon of the reinforcing fibers, especially the carbon fibers. As a result, the valve core 2 and the valve sleeve 3 can be easily and cost-effectively manufactured, wherein the wear of the valve unit 1 due to sliding friction is minimized. The wear is further minimized by the working medium (especially hydraulic oil) in the valve unit 1. The working medium causes liquid friction, which further reduces the wear.

[0029] The valve sleeve 3 preferably has glass fibers as reinforcing fibers, which makes the joint stronger. This can be achieved in the following way: the permissible elongation allowed by the glass fiber reinforced composite material is greater than the elongation that can be achieved when using other fibers as reinforcement.

[0030] It is preferably provided that the composite material of the valve sleeve 3 has a volume ratio of reinforcing fibers of between 30% and 50%, preferably between 35% and 45%, particularly preferably between 38% and 42%, and the composite material of the valve core 2 has a volume ratio of reinforcing fibers of between 20% and 40%, preferably between 25% and 35%, particularly preferably between 28% and 32%. Thus, the force absorption is optimized by the reinforcing fibers in the composite material. In this way, the composite material is optimally suitable for the valve unit 1.

[0031] The composite material of the valve core 2 and / or the valve sleeve 3 also preferably has polytetrafluoroethylene as a filler. Thus, the composite material achieves optimal media tightness, a friction-optimized surface and water-repellent properties.

[0032] In addition to the above written description of the invention, reference is hereby made expressly to Figure 1 and Figure 2 The illustrations of the present invention are used to supplement the disclosure.

[0033] List of Reference Numerals

[0034] 1 Valve unit

[0035] 2 Valve core

[0036] 3 Valve sleeve

[0037] 4 Contact surface

[0038] 5 pairs of contact surfaces

[0039] 6 Electrohydraulic valve

[0040] 7 Electromagnet

[0041] 8 Armature

[0042] 8a Armature rod

[0043] 9 Return spring

[0044] 10 walls

[0045] 100 Longitudinal axis

Claims

1. A valve unit (1), comprising: Valve core (2), and a valve sleeve (3), in which the valve core (2) is movably guided, wherein the valve core (2) is displaceable along the valve sleeve (3) in order to differently set the fluid flow through the valve unit (1), The valve core (2) and the valve sleeve (3) are each formed of a composite material having a base polymer and reinforcing fibers, wherein the base polymers of the valve core (2) and the valve sleeve (3) are similar, The valve core (2) has at least one contact surface (4), the valve core (2) abuts against the valve sleeve (3) with the at least one contact surface, and The contact surface (4) is machined.

2. The valve unit (1) according to claim 1, characterized in that The valve core (2) and / or the valve sleeve (3) are injection-molded parts.

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

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

5. The valve unit (1) according to one of the preceding claims, characterized in that The reinforcing fibers of the valve core (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 core (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 mating contact surface (5) which abuts against a contact surface (4) of the valve core (2), wherein the mating contact surface (5) is not machined.

8. Valve unit (1) according to one of the preceding claims, characterized in that The diameter gap between the valve core (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 core (2).

9. Valve unit (1) according to one of the preceding claims, characterized in that The composite material of the valve sleeve (3) has a volume ratio of reinforcing fibers between 30% and 50%, preferably between 35% and 45%, particularly preferably between 38% and 42%, and / or the composite material of the valve core (2) has a volume ratio of reinforcing fibers between 20% and 40%, preferably between 25% and 35%, particularly preferably between 28% and 32%.

10. An 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 a valve core (2) of the valve unit (1) so as to displace the valve core (2) in at least one direction within the valve sleeve (3).

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