Filter unit for filtering a fluid in a hydraulic system and coupling system with the filter unit

Abstract

Filter unit (5) for filtering a fluid in a hydraulic system, in particular for a coupling system (2), with a housing (10) for arrangement in the hydraulic system, wherein the housing has a flow section (15) for guiding the fluid along a defined flow path (S) through the filter unit (5), with a magnet (9) for separating ferromagnetic particles from the fluid, wherein the magnet is arranged inside the housing (10), wherein the magnet (9) is designed as a ring magnet (16), wherein the flow path (S) runs through a central opening (23) of the ring magnet (16), wherein a circumferential recess (17) is provided in an inner circumference of the housing (10), wherein the ring magnet (16) is recessed in the recess (17), characterized in that the recess (17) is designed as a stepped annular groove, wherein a receiving area (19) for receiving the magnet (16) is formed by a first step of the stepped annular groove, and a trapping area (18a) for forming a trap for the ferromagnetic particles is formed by a second step of the stepped annular groove, and in that a further trapping area (18b) is formed by a third step, wherein the receiving area (19) is axially located between the two Trap areas (18a,b) is arranged such that the ring magnet (16) is spaced apart from the housing (10) on both sides by means of an annular gap in sections.

Description

[0001] The invention relates to a filter unit for filtering a fluid in a hydraulic system, comprising the features of the preamble of claim 1. The invention further relates to a coupling system comprising the filter unit.

[0002] Filter units for hydraulic lines are known for filtering solid particles from hydraulic fluid flowing through the line. Such filter units are used, for example, in hydraulic actuation systems of clutches to prevent damage to dynamic elastomer seals caused by contaminants in the hydraulic fluid. Filters with a tightly woven polymer fabric are used, for instance, to address this problem. It is also known to filter ferromagnetic particles from the hydraulic fluid using a magnet.

[0003] German patent application DE 102015201713 A1, which likely represents the closest prior art, discloses a filter unit for a hydraulic system, in particular for a hydraulic coupling system, for filtering solid components from a hydraulic fluid, comprising a first filter stage which includes at least one of the following filter elements: a cake filter, a cross-flow filter, and a depth filter, and a second filter stage, wherein the second filter stage is configured downstream of the first filter stage in the flow direction and includes at least one magnet for separating magnetizable solid components. A filter unit according to the preamble of claim 1 is known from US patent application 2011 / 0253607 A1. Further prior art is disclosed in US patent application 3,890,232 A and DE patent application 102011 119464 A.

[0004] The object of the present invention is to propose a filter unit characterized by a high separation efficiency and simultaneously exhibiting low flow resistance. Furthermore, the invention aims to propose a coupling system for the filter unit.

[0005] This problem is solved by a filter unit having the features of claim 1 and a coupling system having the features of claim 7. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description, and the accompanying figures.

[0006] The invention relates to a filter unit designed and / or suitable for filtering a fluid in a hydraulic system. In particular, the filter unit is fluidically integrated into the hydraulic system so that the fluid flows through it. The filter unit is especially preferably designed and / or suitable for a hydraulic coupling system. Preferably, the fluid is a hydraulic fluid, more preferably a hydraulic oil.

[0007] The filter unit has a housing designed and / or suitable for installation in the hydraulic system. In particular, the housing has a first and a second fluid opening through which the fluid can flow into and out of the housing. Preferably, the filter unit is arranged and / or can be arranged in the hydraulic system independently of the flow direction, so that, depending on the installation position and / or flow direction, a fluid inlet is formed through one fluid opening and a fluid outlet through the other fluid opening.

[0008] The housing has a flow section which is designed and / or suitable for guiding the fluid along a defined flow path through the filter unit. In particular, the flow section connects the first fluid opening with the second fluid opening. Preferably, the flow section is formed by a through-opening, especially a through-bore.

[0009] The filter unit includes a magnet designed and / or suitable for separating ferromagnetic particles from the fluid, the magnet being arranged within the housing. In particular, the magnet has an effective zone, the flow path of which passes through this zone. The effective zone is defined as an area in which a magnetic field generated by the magnet is sufficiently strong to attract the ferromagnetic particles. Preferably, the fluid is in direct contact with the magnet, so that the fluid flows over it. In particular, the ferromagnetic particles are magnetizable and / or magnetized solid particles, especially metal particles or metal shavings, which are attracted by the magnet and held to it by magnetic interaction.

[0010] Within the scope of the invention, it is proposed that the magnet be designed as a ring magnet. In particular, the ring magnet is designed as a ring-shaped permanent magnet. Preferably, the ring magnet is magnetized axially or radially. Alternatively, however, the ring magnet can also be magnetized diametrically or multipolarly. For example, the ring magnet is made of ferrite or neodymium. Alternatively, however, it can also be provided that the ring magnet is designed as a ring-shaped electromagnet.

[0011] The ring magnet has a central opening, with the flow path passing through this opening. In particular, the effective zone extends over the entire cross-section of the central opening, ensuring that ferromagnetic particles are separated from the fluid at every point within the opening. Preferably, the ring magnet is arranged coaxially and / or concentrically to the housing, especially the flow section. The ring magnet can be held in the housing by a positive fit, a friction fit, and / or a material bond.

[0012] The advantage of the invention lies particularly in the fact that, by designing the magnet as a ring magnet, it can be arranged in a particularly space-saving manner within the housing, while simultaneously allowing the flow path to be guided through the central opening of the ring magnet without interruption. Thus, the fluid can pass through the ring magnet almost unimpeded, significantly reducing pressure differences between the fluid inlet and outlet. This results in a filter unit characterized by very low flow resistance. Furthermore, the ring-shaped design of the magnet allows the effective zone to be configured in such a way that it ensures the separation of ferromagnetic particles across the entire opening cross-section. This results in a filter unit characterized by a particularly high separation efficiency.

[0013] In a specific embodiment of the invention, a circumferential recess is provided in the inner circumference of the housing, with the ring magnet being recessed in the recess. Preferably, the ring magnet is positively locked in the recess in the axial and / or radial direction with respect to a central axis. In particular, the recess forms a negative of the ring magnet. It is especially preferred that the ring magnet is completely recessed relative to the inner circumference of the housing, so that the flow section preferably has a nearly constant cross-sectional profile over its entire length. Preferably, the opening diameter of the central opening of the ring magnet is greater than or equal to the inner diameter of the housing.

[0014] A filter unit is therefore proposed which is characterized by a particularly low flow resistance. By recessing the ring magnet into the housing wall, the fluid can flow unimpeded through the flow section.

[0015] According to the invention, the recess is designed as an annular groove with stepped diameters. In particular, the annular groove is formed by at least or exactly two circumferential ring sections inserted into the inner circumference, which are offset from each other in the axial direction with respect to the central axis.

[0016] Preferably, the annular groove is bounded in the axial direction with respect to the central axis by two opposing flanks.

[0017] According to this embodiment, the annular groove has a receiving area defined by a first stage for receiving the magnet and a trapping area defined by a second stage for forming a trap for the ferromagnetic particles. In particular, the receiving area is formed by one ring section and the trapping area by the other ring section. Preferably, the first stage has a first diameter and the second stage a second diameter, the first diameter being larger than the second diameter. Specifically, the first diameter corresponds to an outer diameter of the ring magnet.

[0018] Preferably, the trap area forms an annular gap circumferentially around the central axis. In particular, the annular gap is bounded in an axial direction with respect to the central axis by an annular surface of the ring magnet and in the opposite axial direction by a lateral flank of the annular groove opposite the annular surface. In an installation configuration, the ring magnet is arranged in the receiving area and held securely against loss, with the ring magnet being axially spaced from the housing section by the annular gap with respect to the central axis. In principle, the trap area can be arranged upstream or downstream of the receiving area or the ring magnet in the flow direction.

[0019] In operation, the fluid flows along the flow path at a flow velocity where the flow velocity is lowest and the magnetic field strength is highest at the location of the annular groove. For this purpose, the ring magnet is preferably axially magnetized, with the magnetic poles arranged on the two opposing annular surfaces. Alternatively, the ring magnet can also be radially magnetized, with the magnetic poles arranged on the inner and outer circumferences. Preferably, the housing is made of a material that is either non-magnetizable or only weakly magnetizable and / or magnetic. For example, the housing is made of anodized aluminum or plastic.

[0020] One aspect of the invention is therefore to propose a filter unit characterized by a particularly high separation efficiency. The trap area allows the ferromagnetic particles to be captured and retained particularly easily. In particular, due to the minimal flow velocity in the trap area, the ferromagnetic particles can be held securely and permanently by the magnet.

[0021] In a further refinement, an additional trap area is formed by a third stage. Specifically, the annular groove is formed by exactly three circumferential ring sections inserted into the inner circumference, each axially offset from the central axis. The two trap areas and the receiving area are each formed by one of the ring sections. Preferably, the third stage has a third diameter, with the second and third diameters being of equal size. The receiving area is arranged axially between the two trap areas. In particular, the additional trap area forms a further annular gap circumferentially around the central axis, so that the ring magnet is sectionally spaced from the housing on both sides by an annular gap.

[0022] Thus, one trap section is positioned upstream and another downstream of the intake area or ring magnet in the direction of flow. This allows the filter unit to be used regardless of the flow direction in the hydraulic system, thereby preventing incorrect installation and increasing installation reliability.

[0023] In a further embodiment of the invention, the housing comprises a first and a second housing component, the two housing components being connected to each other. In particular, the housing is designed in two parts. The housing can be divided radially or axially. Specifically, each of the two housing components can be defined as a housing half. Preferably, the two housing components are connected to each other by a material bond, a force bond, and / or a positive fit. The ring magnet is securely held between the two housing components. Preferably, when mounted between the two housing components, the ring magnet is arranged such that it is held securely between the two housing components.

[0024] One aspect of the invention is therefore to propose a filter unit that is characterized by particularly simple assembly. Furthermore, the ring magnet can be secured very easily to prevent loss.

[0025] In a further development, it is provided that the two housing components are axially divided at the location of the recess. In principle, the two housing components can be mirror-symmetrical, with each housing section forming half of the recess. Preferably, however, one of the two housing sections has the recess, in particular at least the receiving area, with the other housing section limiting or closing the recess axially with respect to the central axis. The ring magnet is mounted and / or mountable in one of the two housing components, in particular in the receiving area, in an axial direction and is held in the opposite axial direction by the other housing component.

[0026] Thus, the ring magnet can be easily mounted between the two housing components without additional fasteners.

[0027] In a further specification, it is provided that one housing component has an end section and the other housing component has a receiving section that accommodates the end section. The ring magnet is inserted into the end section at its end and secured against loss by the receiving section. In particular, the recess is formed completely or at least partially into an inner circumference of the end section, so that the ring magnet can be pre-assembled in the end section. Preferably, the ring magnet can be inserted into the end section in the axial direction and removed from the end section in the opposite axial direction. The receiving section is preferably designed as a projection complementary to the end section, which serves at least for the positive locking of the end section.Preferably, the receiving section has at least one flank defining the recess and / or one of the trap areas, wherein the ring magnet is held in a mounted state by the flank or a step formed by the trap area in the end section or the receiving area.

[0028] Therefore, a housing design is proposed that is particularly compact. Furthermore, the placement of the ring magnet in the end section simplifies the assembly of the housing, as the ring magnet can already be inserted into the housing in the correct orientation.

[0029] In a further specification, it is provided that the end section is detachably connected to the receiving section via a threaded connection. Specifically, the end section has an external thread on its outer circumference, and the receiving section has an internal thread on its inner circumference. Optionally, a sealant, e.g., a sealing ring, is arranged between the end section and the receiving section. Alternatively, it is provided that the end section is permanently connected to the receiving section via a metallurgical bond. Specifically, the end section and the receiving section are metallurgically bonded to each other via a welded or brazed connection.

[0030] One aspect of the invention is therefore to propose a housing that can be assembled particularly easily and quickly, while at the same time enabling a fluid-tight connection between the two housing components.

[0031] In a further embodiment of the invention, the housing has a connection port at each end, which is designed and / or suitable for connecting the hydraulic line. In particular, the first and the second housing components each have the connection port at their end.

[0032] Preferably, both connection fittings are designed as pipe fittings, which serve for a positive-locking and / or force-locking and / or material-locking connection of the hydraulic line. The hydraulic line can be designed as a pipe, a corrugated pipe, or a hose. Specifically, connection fittings serve to form a push-fit connection with the hydraulic line, so that the hydraulic line can be pushed onto and / or pushed onto the connection fitting. Particularly preferably, each of the two pipe fittings has an additional sealing element, e.g., an O-ring, which seals the connection fitting against the hydraulic line.

[0033] This results in a proposed filter unit that can be easily installed or retrofitted into a hydraulic line. The two connection ports also make installation particularly simple.

[0034] Another aspect of the invention relates to a clutch system with the filter unit as previously described. Preferably, the clutch system is arranged and / or can be arranged for interrupting a drive torque in a vehicle's drivetrain. For this purpose, the clutch system comprises a master cylinder and a slave cylinder, which are connected to each other by a hydraulic line. The master cylinder can be connected to a clutch pedal or a clutch actuator. The slave cylinder can be connected to a release bearing, which serves to transmit a release movement to a clutch device, in particular a friction clutch. When the master cylinder is actuated, a column of fluid is preferably moved via the hydraulic line towards the slave cylinder, so that the release movement is transmitted to the release bearing.Subsequently, the release cylinder and the slave cylinder are automatically returned to their starting position, with the fluid column being pushed back towards the master cylinder.

[0035] According to this design, the filter unit is positioned between the master cylinder and the slave cylinder in the hydraulic line. Due to operational wear, the hydraulic fluid can become contaminated with ferromagnetic particles over time due to wear of the master and / or slave cylinder. These particles are attracted by the ring magnet as the fluid flows through the filter unit and are retained within the filter unit, particularly in the trap areas.

[0036] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments of the invention. These include: Fig. 1 a highly schematic representation of a coupling system as an embodiment of the invention, Fig. 2 a schematic sectional view of a filter unit of the coupling system made of Fig. 1 as a further embodiment of the invention.

[0037] Corresponding or identical parts are each provided with the same reference symbols in the figures.

[0038] The Fig. Figure 1 shows a highly schematic representation of a clutch system 1, which is designed and / or suitable, for example, for a vehicle's manual transmission. The clutch system 1 comprises an actuating device 2, a master cylinder 3, a hydraulic line 4, a filter unit 5, a slave cylinder 6, a transmission device 7, and a clutch assembly 8.

[0039] For example, the actuating device 2 is designed as an actuating actuator or clutch pedal operatively connected to the master cylinder 3. The master cylinder 3 is fluidly connected to the slave cylinder 6 via the hydraulic line 4 to form a hydraulic circuit, with the filter unit 5 being arranged in the hydraulic line 4 between the master cylinder 3 and the slave cylinder 6. The slave cylinder 6 is also operatively connected to the transmission device 7 to transmit a disengagement movement to the clutch device 8. For example, the transmission device 7 is designed as a disengagement system that transmits the disengagement movement to the clutch device 8 as a mechanical movement.

[0040] During a disengagement process, the actuating device 2 is actuated, whereby the master cylinder 3 performs a stroke movement. A column of fluid is thereby displaced from the master cylinder 3 via the hydraulic line 4 and the filter unit 5 towards the slave cylinder 6. The slave cylinder 6 thus performs a further stroke movement, which is transmitted to the transmission device 7 and thus transferred as the disengagement movement to the clutch device 8. For example, the clutch device 8 is designed as a friction clutch, whereby the disengagement movement releases the frictional engagement of the clutch device 8 and the clutch device 8 is disengaged.

[0041] During an engagement process, the actuating device 2 is relieved of pressure, whereby the transmission device 7 and the slave cylinder 6 are automatically returned to a starting position and the clutch device 8 is re-engaged. The fluid column is thereby moved from the slave cylinder 6 via the hydraulic line 4 and the filter unit 5 back towards the master cylinder 3, so that the master cylinder 3 is returned to a starting position.

[0042] Due to operational factors, hard particles can enter the fluid over the service life of the clutch system 1 as a result of wear. These particles can, for example, lead to increased wear of the dynamic seals (not shown) of the master and slave cylinders 3 and 6, thus shortening their service life. Typically, a large proportion of the hard particles exhibit ferromagnetic properties, allowing them to be filtered by magnetic forces. For this purpose, the filter unit 5 is designed as a magnetic filter, which separates the ferromagnetic particles from the hydraulic fluid flowing through the hydraulic line by means of a magnet 9. The magnet 9 can preferably be a permanent magnet or, alternatively, an electromagnet.

[0043] This significantly reduces the number of hard particles that reach the dynamic seals.

[0044] Fig.Figure 2 shows the filter unit 5 in a schematic sectional view as a further embodiment of the invention. The filter unit 5 has a substantially cylindrical housing 10, which is formed by a first and a second housing component 11, 12. The two housing components 11, 12 are arranged coaxially with respect to a central axis M, wherein the first housing component 11 has a first fluid opening 13 and the second housing component 12 has a second fluid opening 14. The two fluid openings 13, 14 are fluidically connected to each other via a flow section 15, wherein the fluid is guided through the housing 10 along a flow path S via the flow section 15. For example, the flow section 15 is formed by a through-bore extending coaxially to the central axis M.

[0045] The magnet 9 is designed as a ring magnet 16 and is arranged within the housing 10 between the two housing components 11, 12. For this purpose, the housing 10 has a recess 17, which is formed in an inner circumference of the housing 10. The recess 17 is designed as a stepped annular groove, with the recess 17 having three annular sections 17a, b, c, which are offset from each other in the axial direction with respect to the central axis M. The two outer annular sections 17a, b each define a trap area 18a, b, with a central annular section 17c arranged between the two outer annular sections 17a, b defining a receiving area 19 for receiving the ring magnet 16. The central annular section 17c is recessed relative to the two outer annular sections 17a, b, so that the ring magnet 16 is positively locked in the annular groove in the axial direction with respect to the central axis M.

[0046] The two trap regions 18a, b are formed on both sides of the ring magnet 16 as an annular gap circumferencing the central axis M, such that the ring magnet 16 is spaced section by section from the two housing sections 11, 12 in an axial direction AR and an axial opposite direction GR. The two trap regions 18a, b form a trap for the ferromagnetic particles, with the fluid flow velocity being lowest and the field strength of the electric magnetic field generated by the ring magnet 16 being strongest in each trap region 18a, b. As the fluid flows through the filter unit 5, it flows along the flow path S, whereby the ferromagnetic particles are selectively trapped in one of the two trap regions 18a, b, depending on the flow direction, and held by the ring magnet 16. The ring magnet 16 is, for example, magnetized axially or radially.

[0047] To connect the two housing components 11, 12, the first housing section 11 has an end section 20 and the second housing section 12 has a receiving section 21, which serves to receive the end section 20. The recess 19 is defined by the two housing components 11, 12, with the end section 20 having one of the trap areas 17a and the receiving area 17c on its inner circumference, and the receiving section 21 having the other trap area 17b on its inner circumference. During assembly, the ring magnet 16 is first inserted axially AR into the receiving area 19 of the end section 20 and then secured against loss in the opposite axial direction GR by the receiving section 21.

[0048] The receiving section 21 is, for example, designed as a hollow cylindrical nozzle, with the end section 20 being inserted or screwed into the receiving section 21 in the axial opposite direction GR. The end section 20 and the receiving section 21 are connected to each other in a connection area 22 either by a material bond, for example by means of a soldered or welded connection, or by a form-fit connection, for example via a threaded connection.

[0049] The ring magnet 16 has a central opening 23, through which the flow path S is guided. The ring magnet 16 is arranged coaxially and / or concentrically with respect to the central axis M of the two housing components 11, 12, with the opening 23 having an inner diameter that is greater than or equal to the inner diameter of the flow section 15. This allows the ring magnet 16 to be radially recessed in the housing 10. This ensures that the filter unit 5 in the area of ​​the ring magnet 16 exhibits little or no flow resistance, thereby reducing or eliminating pressure drop in the overall system, particularly the coupling system 1, and thus preventing any negative impact on the actuation speed of the master and slave cylinders 3, 6.

[0050] The first and second housing components 11, 12 each have a connection port 24a, b at their end, which serves to connect the hydraulic line 4. For example, the hydraulic line 4 is formed by a tube on each side, which can be fluid-tightly pushed onto one of the connection ports 24a, b at its end. For this purpose, the two connection ports 24a, b each have a sealing element 25a, b, e.g., an O-ring. Reference symbol list 1 coupling system 2 Actuating device 3 master cylinders 4 Hydraulic lines 5 filter units 6 slave cylinders 7 Transmission device 8 Coupling device 9 Magnet 10 cases 11 first housing component 12 second housing component 13 first fluid opening 14 second fluid opening 15 Flow section 16 Ring magnet 17 Further Study 18a, b Trap areas 19 Recording area 20 Final section 21 Recording section 22 Connection area 23 Opening 24a, b Connection spigot 25a, b Sealant AR axial direction GR axial opposite direction M Central axis S Flow path

Claims

[1] Filter unit (5) for filtering a fluid of a hydraulic system, in particular for a coupling system (2), with a housing (10) for arrangement in the hydraulic system, wherein the housing has a flow section (15) for guiding the fluid along a defined flow path (S) through the filter unit (5), with a magnet (9) for separating ferromagnetic particles from the fluid, wherein the magnet is arranged inside the housing (10), wherein the magnet (9) is designed as a ring magnet (16), wherein the flow path (S) runs through a central opening (23) of the ring magnet (16), wherein a circumferential recess (17) is provided in an inner circumference of the housing (10), wherein the ring magnet (16) is arranged recessed in the recess (17), characterized by, that the recess (17) is designed as a stepped annular groove, wherein a receiving area (19) for receiving the magnet (16) is formed by a first step of the stepped annular groove and a trapping area (18a) for forming a trap for the ferromagnetic particles is formed by a second step of the stepped annular groove and that a further trapping area (18b) is formed by a third step, wherein the receiving area (19) is arranged axially between the two trapping areas (18a, b) so that the ring magnet (16) is spaced section by section on both sides from the housing (10) by means of an annular gap. [2] Filter unit (5) according to claim 1, characterized by , that the housing (10) has a first and a second housing component (11, 12), wherein the two housing components (11, 12) are connected to each other and wherein the ring magnet (16) is securely held between the two housing components (11, 12). [3] Filter unit (5) according to claim 2, characterized by , that the two housing components (11, 12) are axially divided at the location of the recess (17), wherein the ring magnet (16) is mounted and / or mountable in one of the two housing components (11, 12) in an axial direction (AR) and is held in an axial opposite direction (GR) by the other housing component (11, 12). [4] Filter unit (5) according to claim 2 or 3, characterized by , that one of the two housing components (11, 12) has an end section (20) and the other housing component (11, 12) has a receiving section (21) receiving the end section (20), wherein the ring magnet (16) is inserted end-side into the end section (20) and is secured against loss by the receiving section (21). [5] Filter unit (5) according to claim 4, characterized bythat the end section (20) is detachably connected to the receiving section (21) via a threaded connection or that the end section (20) is indetachably connected to the receiving section (21) via a material bond. [6] Filter unit (5) according to any one of the preceding claims, characterized by , that the housing (10) has at each end a connection port (24a, b) for connecting a hydraulic line (4). [7] Coupling system (1) with the filter unit (5) according to one of the preceding claims, characterized by a master cylinder (3) and a slave cylinder (6) which are connected to each other by a hydraulic line (4), wherein the filter unit (5) is arranged between the master cylinder (3) and the slave cylinder (6) in the hydraulic line (4).

Images