EP2308063A1

EP2308063A1 - Electromagnetic actuating unit of a hydraulic directional valve

Info

Publication number: EP2308063A1
Application number: EP09780129A
Authority: EP
Inventors: Jens Hoppe; Markus Kinscher
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2008-07-23
Filing date: 2009-07-03
Publication date: 2011-04-13
Also published as: US8581683B2; WO2010009966A1; DE102008037076A1; US20110121218A1; CN102105952A

Abstract

The invention relates to an electromagnetic actuating unit (1) of a hydraulic directional valve, comprising an armature (13) and a first and a second magnet yoke (6, 9), wherein the first and the second magnet yokes (6, 9) at least partially bound an armature space (12), wherein the armature (13) is arranged in the armature space (12) so as to be axially displaceable, and wherein the first and the second magnet yokes (6, 9) face each other in the axial direction of the armature (13).

Description

Name of the invention

Electromagnetic actuator of a hydraulic directional control valve

description

Field of the invention

The invention relates to an electromagnetic actuator of a hydraulic directional control valve, comprising an armature, a first and a second yoke, wherein the first and the second yoke at least partially define an armature space, wherein the armature is arranged axially displaceable in the armature space and wherein the first and second magnetic yoke facing in the axial direction of the armature.

Such directional control valves are used, for example, in internal combustion engines, for example, to control switchable cam followers, for example switchable bucket tappets, roller tappets or drag levers, or of hydraulic camshaft adjusters. The directional control valves consist of an electromagnetic actuator and a valve section. The valve section represents the hydraulic section of the directional control valve, wherein at least one inlet connection, at least one working connection and a tank connection are formed on the latter. By means of the electromagnetic actuator unit, certain connections of the valve section can be hydraulically connected to one another and thus the pressure medium flows can be directed.

Such directional control valves may be integrally formed, wherein the electromagnetic actuator is fixedly connected to the valve portion. In these cases, the directional control valve is positioned in a receptacle formed, for example, on a cylinder head or a cylinder head cover, and connected via pressure medium lines to the pressure chambers of the camshaft adjuster.

In another embodiment, the electromagnetic actuator and the valve portion are designed as separate components. It is, for example, conceivable to arrange the valve portion within a receptacle which is formed on an inner rotor, a camshaft or an extension of the camshaft. The valve portion is arranged coaxially with the camshaft and the inner rotor in this case and rotates together with these about the common axis of rotation.

In the axial direction to the valve portion, the electromagnetic actuator is arranged, which is fixedly fixed, for example, to a chain case or the like. The electromagnetic actuator controls the axial position of a push rod, which in turn controls the axial position of a control piston of the valve portion.

For the use of a directional control valve for controlling a camshaft adjuster, this is normally designed as a 4/3 or 4/2 proportional directional control valve. Such a proportional valve is known for example from DE 10 2005 048 732 A1. The electromagnetic actuator in this case consists of a first and a second magnetic yoke, a coil, a housing, an armature and a connection element which receives an electrical plug connection, which serves to supply power to the coil.

The coil, the first and the second magnetic yoke are arranged coaxially within the housing of the electromagnetic actuator. The first and the second magnetic yoke form an armature space. Within the armature space an axially displaceable armature is arranged, on which a push rod is fixed, which engages through an opening of the second magnetic yoke and is supported in this opening in the radial direction. The armature, the housing, the first and the second magnetic yoke form a flux path for the magnetic flux lines, which are caused by energizing the coil.

The valve section consists of a valve housing and a control piston arranged axially displaceable therein. The valve housing is disposed within an inner rotor of a camshaft adjuster. On the interior Tor is arranged rotatably to this outer rotor mounted, which is in the illustrated embodiment by means of a chain drive in drive connection with a crankshaft.

On the outer lateral surface of the valve housing several Druckmittelan- conclusions are formed, which serve as inlet, outlet port and working connections. The working connections communicate with counteracting pressure chambers formed within the camshaft adjuster. In the interior of the valve housing, a control piston is arranged axially displaceable, wherein the outer diameter of the control piston is adapted to the inner diameter of the valve housing. On the outer circumferential surface of the control piston annular grooves are formed, via which adjacent pressure medium connections can be connected to each other.

By energizing the coil, the armature is urged in the direction of the valve portion, wherein this movement is transmitted by means of an anchor rod attached to the control piston. This is now moved in the axial direction against a spring supported on the valve housing, whereby the pressure medium flow is controlled from the inlet port to one of the working ports and from the other working port to the drain port. As a result, the pressure chambers of the camshaft adjuster pressure medium to be supplied or discharged therefrom, whereby the phase angle of the camshaft can be varied to form a crankshaft.

The first and the second magnetic yoke are separated in the axial direction by an air gap. Within the first magnetic yoke, a pot-shaped armature guide sleeve is arranged, in which the armature is mounted. The armature guide sleeve abuts against an inner circumferential surface of the first magnetic yoke, wherein the second magnetic yoke is inserted into the armature guide sleeve. A disadvantage of this embodiment is that between the armature and the second magnetic yoke, due to the armature guide sleeve, a relatively large distance is present. Thus, the transfer of the magnetic field lines from the armature to the first magnetic yoke is disturbed, resulting in a reduction of the force on the armature. Consequently, the coil must be designed for higher currents in order to achieve the required performance of the actuator, resulting in higher leads to higher production costs. Furthermore, during operation, higher currents flow in the coil, which leads to a higher heat development.

DE 10 2006 027 349 A1 shows a further embodiment of an electromagnetic actuating unit. In this embodiment, the armature is mounted on a pin, which is attached on the one hand to the first magnetic yoke and engages in the axial direction in a bore of the armature. This leads to an increase in the number of components and the tolerance chain between the components.

Summary of the invention

The invention is therefore based on the object to avoid these disadvantages and thus to provide an electromagnetic actuator, the performance should be improved.

According to the invention the object is achieved in that on an outer circumferential surface of the armature or an inner circumferential surface of the first and the second magnetic yoke a voltage applied to the armature bearing for supporting the armature is arranged on the magnetic yoke, wherein the sliding bearing at each position of the armature relative to the Magnetic yoke is arranged outside the region in which opposite ends of the first magnetic yoke and the second magnetic yoke.

The electromagnetic actuating unit of a hydraulic directional valve has a magnetic circuit which comprises at least one armature, a first and a second magnetic yoke. The first magnetic yoke is arranged axially offset from the second magnetic yoke. In this case, an air gap between opposite ends of these two components can be provided. The first and the second magnetic yoke surround an armature space at least partially. In the armature space, the armature is displaceably arranged in the axial direction. The armature, the first and second yoke form a magnetic circuit, which is completed by additional components, such as a housing of the actuator. Usually, the actuator takes on a coil. By energizing the Coil acts on the armature by a force urging it into the region in which the ends of the first and second yoke face each other.

At the armature or the first or second magnetic yoke, a slide bearing is provided in order to store the armature in the armature space with low friction. The slide bearing may be attached to the anchor. In this case, the slide bearing is stationary on the anchor. Likewise conceivable are embodiments in which the sliding bearing is attached to the first or second magnetic yoke. In this case, the sliding bearing is arranged such that the sliding bearing rests in any position of the armature within the armature space on the armature. The friction bearing between the armature and the yoke is lowered by the sliding bearing and thus significantly reduces the hysteresis of the characteristic of the electromagnetic actuator. If the slide bearing is attached to the armature, then it is advantageously arranged such that this does not occur in any position of the armature in the armature space in the area in which the two ends of the first and second magnetic yoke facing each other, in particular that it is not the area of Air gap covered.

If this is the slide bearing attached to the magnetic yoke, it is advantageously arranged so that this takes over storage function at each position of the armature, but at the same time located at maximum distance to the area in which the ends of the first and the second Magnetic yoke face.

The advantage of this arrangement is that the force generated by the magnetic field of the coil is not weakened on the armature. The magnetic field occurs in the region in which the ends of the first and second magnetic yoke facing each other from the first magnetic yoke in the armature and on in the second magnetic yoke. By the invention, the radial distances between the armature and the first and second magnetic yoke can be reduced to a minimum. Moreover, no further component between armature and yoke is provided at the transfer points. The flow line passage can thus be made optimally, resulting in an optimal implementation of the magnetic field in a force on the armature. The maximum required current drops, with the same power development. In a further development of the invention, provision is made for a first recess to be provided on the outer circumferential surface of the armature or of the inner lateral surface of the first or the second magnetic yoke, in which the sliding bearing is arranged. In this case, the first recess may be formed as circumferential groove in the circumferential direction. For example, its outer circumferential surface may be provided with an annular groove on an axial end face of the armature. In this so-formed paragraph, the slide bearing can be postponed with minimal projection or otherwise attached. Thus, the radial distance between see anchor and yoke further reduced and thus the force acting on the armature can be increased.

Furthermore, it can be provided that on the component from the group armature or yoke, on which the sliding bearing is not attached, a second recess is provided, which faces the first recess in the radial direction. The sliding bearing arranged in the first recess also engages in the second recess. Thus, the radial distance between the armature and magnetic yoke can be further reduced and thus the force acting on the armature can be increased.

The plain bearing may be formed, for example, annular or segmented.

Furthermore, the plain bearing can be provided with a stop which the

Movement of the anchor limited in one direction. Thus, without additional components, a travel limitation of the armature can be realized. It can be provided that the stop only partially covers the surface of the armature perpendicular to its direction of movement. Thus, it is prevented that the anchor comes to rest flat against one end of the armature space. This prevents the anchor from adhering to the surface, which has a positive effect on the hysteresis of the characteristic and reduces the force required.

The plain bearing can be attached, for example, force, shape or cohesively to the armature or the magnetic yoke. The sliding bearing may be fixed to the armature or the magnetic yoke by means of a press fit, an adhesive or solder joint. Likewise conceivable are embodiments in which the sliding bearing is caulked with the armature or the yoke or is sprayed onto the armature or the magnetic yoke. The plain bearing can be made as a separate component and subsequently connected to the respective component, or be sprayed directly onto this.

Brief description of the drawings

Further features of the invention will become apparent from the following description and from the drawings, in which embodiments of the invention are shown in simplified form. Show it

1 shows a first embodiment of an electromagnetic actuator in longitudinal section,

FIG. 2 is an enlarged view of the electromagnetic actuator of FIG. 1;

FIG. 3 shows a representation of a second embodiment of an electromagnetic setting unit analogous to FIG. 2,

FIG. 4 shows an armature of a third embodiment of an actuating unit according to the invention in longitudinal section,

Figure 5, the anchor of Figure 4 in a perspective view.

Detailed description of the drawing

Figures 1 and 2 show a first embodiment according to the invention an electromagnetic actuator 1 in longitudinal section. The electromagnetic actuator 1 has a bobbin 2 and an integrally formed with this Detes connection element 3. The bobbin 2 carries a coil 4 consisting of several turns of a suitable wire and is at least partially surrounded by a reversion 5 of non-magnetizable material. Within the encapsulation 5, a first magnetic yoke 6 is arranged, which in the illustrated embodiment has a disk-like and a sleeve-like portion 6a, 6b. The sleeve-like portion 6b engages in a cavity radially within the encapsulation 5 of the coil 4, wherein the outer diameter of the inner diameter of the encapsulation 5 is adjusted. The disk-like section 6a abuts the encapsulation 5 in the axial direction and thus determines the axial position of the first magnetic yoke 6.

The bobbin 2 is further arranged in a cup-shaped housing 7, in the bottom of a receiving opening 8 is provided. In the receiving opening 8, a second magnetic yoke 9 is received, which projects into the extrusion coating 5 in the axial direction. In this case, the open ends 10 of the first and second magnetic yoke 6, 9 are axially opposite one another via an air gap 11.

The first and second magnetic yokes 6, 9 delimit an armature space 12, in which an axially displaceable armature 13 is arranged. An associated with the armature 13 push rod 14 extends through an opening formed on the second yoke 9 opening 15, wherein one end of the push rod 14 in the assembled state of the actuating unit 1 rests against a control piston of the directional control valve, not shown. Within the opening 15, a sliding sleeve 16 may be provided to minimize friction losses at this point.

During operation, the energization of the control unit 1 is regulated, whereby a magnetic field within the control unit 1 is generated. The first magnetic yoke 6, the housing 7, the second magnetic yoke 9 and the armature 13 serve as a flow path, which is completed by the air gap 11 between the armature 13 and the first and second magnetic yoke 6, 9. In this case, a force acts in the direction of the second magnetic yoke 9 on the armature 13, which is dependent on the amount of current supplied to the coil 4. By balancing the magnetic force acting on the armature 13 and a spring force acting on the armature 13 Control piston acts, the armature 13 and thus the control piston can be positioned in any position between two extreme positions.

On the outer circumferential surface 17 of the armature 13, an annular sliding bearing 18 is provided. For this purpose, the armature 13 has a first recess 19 in the form of an annular groove in which the sliding bearing 18 is arranged. The sliding bearing 18 has only a slight projection with respect to the outer circumferential surface 17 of the armature 13 and abuts against an inner circumferential surface 20 of the first magnetic yoke 6. In this case, the sliding bearing 18 is arranged in such a way that, in the case of no position of the armature 13, the latter is immersed in the region of the air gap 11 which separates the opposing ends 10 of the first and second magnetic yokes 6, 9. Thus, the flux lines of the magnetic field in the region of the air gap 11 can optimally pass between the armature 13 and the magnetic yoke 6, 9, since no component is arranged between them and the radial distances are small. Thus, the force acting on the armature 13 is optimized. The arrangement of the sliding bearing 18 on the armature 13, no recess on the thin-walled first magnetic yoke 6 is required, which would lead to a reduction of the force due to the disturbance of the magnetic flux by the narrowing of the flow path. The first mating 19 on the armature 13 hardly disturbs the magnetic flux, since this component is solid.

Also conceivable are embodiments in which the inner circumferential surface 20 of the first magnetic yoke 6 has a recess 19 in which a sliding bearing 18 is arranged or that the sliding bearing 18 as a thin layer on the outer circumferential surface 17 of the armature 13 or the inner circumferential surface 20 of the first magnetic yoke. 6 is formed, wherein the layer is arranged such that it dips into any position of the armature 13 in the air gap 11, but always rests against the armature 13.

At the push rod 14 facing away from the end face of the armature 13, a stop sleeve 23 is provided, which is arranged in an axial bore of the armature 13. The stop sleeve 23 is in the axial direction of the end face of the armature 13, not completely covering them. Thus, the stop sleeve 23 limits a displacement of the armature 13 in one of the two directions of movement. At the same time, the stop sleeve 23 prevents the front face of the armature 13 from coming into contact flat against the first magnetic yoke 6. Thus, it is avoided that due to adhesion, a higher force is needed to move the armature 13 out of this position.

FIG. 3 shows a second embodiment of an electromagnetic setting unit 1. In contrast to the first embodiment, here the first magnetic yoke 6 in the region of the sliding bearing 18 has a second recess 21, also in the form of an annular groove. The sliding bearing 18 is arranged in the first recess 19 and secured to the armature 13. At the same time, it engages in the second recess 21. In this case, the axial length of the second recess 21 is designed such that it does not hinder the movement of the armature 13. By forming the two recesses 19, 21, the radial distance between the armature 13 and the first and second magnetic yoke 6, 9 can be further reduced. Likewise conceivable are embodiments in which the slide bearing 18 is attached to the first magnetic yoke 6 and the second recess 21 is formed on the armature 13.

Figures 4 and 5 show the armature 13 of a third embodiment of an electromagnetic actuator according to the invention 1. In contrast to the second embodiment, the sliding bearing 18 is not annular, but formed segmented. This allows communication of the spaces axially in front of and behind the armature 13. Thus, upon movement of the armature 13 air or lubricant can be transported between the rooms and thus a pressure build-up can be avoided. In addition, lubricant is easier to get to the bearings. In addition, in this embodiment, a stop 22 is integrally formed on the slide bearing 18, which assumes the function of the stop sleeve 23. Thus, the number of components of the actuator 1 and thus their costs and installation costs decreases. reference numeral

1 actuator

2 bobbins

3 connection element

4 coil

5 reversion

6 first magnetic yoke

6a disc-like section

6b sleeve-like section

7 housing

8 receiving opening

9 second yoke

10 end

11 air gap

12 anchor room

13 anchors

14 pushrod

15 opening

16 sliding sleeve

17 outer lateral surface

18 plain bearings

19 first recess

20 inner lateral surface

21 second recess

22 stop

23 stop sleeve

Claims

claims

1. Electromagnetic actuator (1) of a hydraulic directional control valve, with

an armature (13), a first and a second magnetic yoke (6, 9), wherein the first and the second magnetic yoke (6, 9) at least partially delimit an armature space (12),

- Wherein the armature (13) is arranged axially displaceable in the armature space (12) and

- Wherein the first and second magnetic yoke (6, 9) in the axial direction of the armature (13) facing, characterized in that

- On an outer circumferential surface (17) of the armature (13) or an inner circumferential surface (20) of the first and the second yoke (6, 9) on the armature (13) fitting slide bearing (18) for supporting the armature (13) the magnetic yoke (6, 9) is arranged, - wherein the sliding bearing (18) is arranged at each position of the armature (13) relative to the magnetic yoke (6, 9) outside the range in which ends (10) of the first magnetic yoke (6) and the second magnetic yoke (9) face.

2. Electromagnetic actuator unit (1) according to claim 1, characterized in that on the outer lateral surface (17) of the armature (13) or the inner lateral surface (20) of the first and the second magnetic yoke (6, 9) has a first recess (19). is provided, in which the sliding bearing (18) is arranged.

3. Electromagnetic actuator (1) according to claim 2, characterized in that the first recess (19) is designed as a peripheral circumferential groove.

4. Electromagnetic actuator (1) according to claim 2, characterized in that on the component from the group armature (13) or yoke (6, 9) on which the sliding bearing (18) is not attached, a second output Savings (21) is provided, which faces the first recess (19) in the radial direction.

5. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) with a stop (22) is provided which limits the displacement of the armature (13) in one direction.

6. Electromagnetic actuator (1) according to claim 5, characterized in that the stop (22) only partially covers the surface of the armature (13) perpendicular to its direction of movement.

7. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) is annular.

8. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) is formed segmented.

9. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) is positively, positively or materially secured to the armature (13) or the yoke (6, 9).

10. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) by means of press fit to the armature (13) or the yoke (6, 9) is attached.

11. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) with the armature (13) or the yoke (6, 9) is caulked.

12. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) on the armature (13) or the magnetic yoke (6, 9) is sprayed.

13. Electromagnetic actuator (1) according to claim 1, characterized in that the sliding bearing (18) by means of an adhesive or solder joint to the armature (13) or the yoke (6, 9) is fixed.