EP1179121B1 - Electromagnetic multiple actuator - Google Patents

Description

The invention relates to an electromagnetic multiple actuator, especially for two gas exchange valves one Internal combustion engine.

Actuators for gas exchange valves of internal combustion engines are known. In contrast to camshaft operated valves are electromagnetically driven valves for opening and Closing depending on the rotational position of the crankshaft driven. The actuator must be capable of high Apply forces, especially when opening an exhaust valve, and the respective end position of the gas exchange valve when opening and closing must be reached with certainty become.

An electromagnetic actuator is off, for example known from DE 197 35 375 C2. It has an anchor that of two springs in a middle position between two electromagnets is held. By energizing one of the electromagnets can the anchor in the respective, the electromagnet assigned end position tightened and held there become. To the actuator and thus the one driven by it To transfer the gas exchange valve from one end position to the other, the current supply to the holding coil is ended and the other coil is energized, causing the armature under the force the springs and the electromagnet switched on in the other end position is moved.

To control the actuator movement, for example Control of the valve movement in an internal combustion engine must the stroke movement of the actuator can be measured continuously. In an internal combustion engine, the valve lift of a gas exchange valve is usually 8 mm.

This stroke must be measured to around 1/100 mm to enable effective valve control.

To this end, it is known to measure the inductance of the winding To measure electromagnets (EP 0 500 389) or an eddy current sensor or an optical position transmitter (EP 0 493 634) use to detect the position of the anchor.

The electromagnetic drive of the actuator must be considerable Apply forces, which is why the surface of the anchor and the electromagnet should be chosen as large as possible should and on the other hand a strong thermal load the electromagnet results. However, that is available Installation space for an actuator, for example a Drives gas exchange valve of an internal combustion engine, limited.

One way to address the thermal problems with such To solve the actuator would be a connection to a cooling circuit, for example, the cooling circuit of an internal combustion engine. However, this would require an intolerably great effort.

In addition, the actuators mentioned above are relative difficult to assemble because it is made up of many individual parts are.

The invention is therefore based on the object of an electromagnetic To specify actuator that is compact in is able to apply high forces and without connection a cooling circuit needs.

This object is achieved by the invention defined in claim 1 solved.

In the concept according to the invention, at least two individual actuators are used combined into a multiple actuator. On such multiple actuator has a housing through which at least two anchor shafts run, each with an anchor is attached, which lies between two electromagnets and from two springs is held in a rest position.

With this concept, the multiple actuator on the bottom, i.e. the side, for example the gas exchange valves is facing in an internal combustion engine, large area on a cooled surface, for example the cylinder head an internal combustion engine. Here is the Available area of this cooled part optimally from Multiple actuator covered, since the normally between Individual actuators remaining gap is eliminated. Through the Combination of several single actuators in one housing can maximize the area of the armature and its electromagnet become. Finally, through the large side wall of the multiple actuators a good heat connection of the Top of the actuator to the contact on the cooled part Given bottom.

The springs are preferably outside the housing. Then the coil cores are easier to attach.

The housing also takes over the longitudinal guidance of the anchors the axis of the anchor shaft, so that one at the state of Technology necessary separate anti-rotation lock can be omitted, because due to the longitudinal guidance, the anchor is no longer that of the Springs caused rotation can follow.

The structure according to the invention further reduces the parts of the Actuator, which considerably simplifies assembly becomes. The housing is preferably first manufactured in one piece and then broken at predetermined breaking points, so that after the Assemble the housing parts by bolts that pass through run at least one side wall, are held together, an optimal fit is achieved.

Measuring the position of the armature of each actuator part is preferably carried out by contactless measurement using a magnetic field sensitive Sensor attached to the housing of the multiple actuator are attached, and assigned permanent magnets, each firmly attached to the anchor are. Each permanent magnet creates a stray magnetic field. The associated magnetic field sensitive sensor, whose Signal preferably only from the direction of the magnetic Depends on the field, detects the position of the permanent magnet and thus the position of the anchor. The multiple actuator drives Gas exchange valves on an internal combustion engine is the Position of the armature assigned to that of the respective gas exchange valve.

The principle according to the invention applies to entire actuator strips applicable, for example, all actuators of the Inlet or outlet side of an internal combustion engine in one Actuator strip are united. Then to take the lead The anchor can be secured using vertical partition walls be provided in the housing.

Preferred embodiments of the invention are in the subclaims characterized.

Fig. 1

eine Schnittdarstellung durch einen Mehrfachstellantrieb,

Fig. 2

eine Explosionsdarstellung eines Gehäuseunterteils eines Mehrfachstellantriebes mit unterem Spulenkern und Laufbuchsen,

Fig. 3

eine Explosionsdarstellung eines Gehäuseunterteils eines Mehrfachstellantriebes mit eingebautem Spulenkern sowie mit zwei unteren Wicklungen und

Fig. 4

eine perspektivische Darstellung eines Mehrfachstellantriebes.

The invention is explained in more detail below with reference to the drawing in an exemplary embodiment. The drawing shows:

Fig. 1

2 shows a sectional view through a multiple actuator,

Fig. 2

an exploded view of a lower housing part of a multiple actuator with lower coil core and liners,

Fig. 3

an exploded view of a lower housing part of a multiple actuator with built-in coil core and with two lower windings and

Fig. 4

a perspective view of a multiple actuator.

In Fig. 1 is a section through an electromagnetic Multiple actuator shown, the at least two poppet valves drives the gas exchange valves of an internal combustion engine are. For example, the multiple actuator drives two intake valves of a cylinder. The section of Fig. 1st however shows only one of these valves with the associated Actuator part.

The electromagnetic multiple actuator of Fig. 1 is on Cylinder head 60 attached and drives an internal combustion engine a gas exchange valve. To do this, the multiple actuator in one housing for each gas exchange valve to be driven plate-shaped anchor 10 on an anchor shaft 9 sits, which in turn rests on a valve stem 64. The armature shaft 9 projects into a recess 63 of the cylinder head 60, in which the gas exchange valve sits, one Has valve plate 62 with valve seat 61.

The valve plate 62 is supported by a spring 68, which is between a Washer 69 in the recess 63 on the cylinder head 60 rests, and one attached to the valve stem 64 Valve spring plate 67 is clamped, up to an end position pressed down in the valve seat 61, the gas exchange valve closes.

The spring 68 also acts on the armature shaft 9 and Anchor 10. Your counteracting is between one at anchor attached anchor spring plate 13 and one on the housing a spring 12 clamped on the washer 11, which pushes the anchor shaft 9 down.

The armature 10 is located in the housing, which consists of a lower Housing part 3, an upper housing part 1 and a middle housing part 2 is built between two electromagnets. The lower electromagnet consists of a lower coil core 6 and a lower winding 8, the upper electromagnet an upper coil core 5 and an upper winding 7. Die Housing parts are screwed together.

The windings 7, 8 are made by suitable driver circuits energized, which are controlled by a control circuit (not shown).

The end faces of the coil cores are stops for the armature 10 and define its end positions. The springs 12, 68 keep the armature 10 in a de-energized windings 7, 8 in one Resting position between these end positions, from which he the electromagnet can be deflected.

The three-part housing is made of die-cast aluminum. The housing parts 1, 2, 3 are made of four stud bolts 58 held together by the top 14 of the housing to the bottom 15 run and screwed to the cylinder head 60 are.

Through the housing of the electromagnetic multiple actuator run several anchor stems 9. Each is in bushings 4 led. For each anchor shaft 9 is a bushing 4 in Upper housing part 1, the other fixed in the lower housing part 3.

In Figs. 2 and 3 is the lower housing part 3 with the Coil core 6 and the windings 8 shown in more detail.

In Fig. 2 it can be seen that for the multiple actuator only a single lower coil core 6 for all electromagnets the bottom is provided. This coil core 6 has suitable Slots 19 for receiving the windings 8 and a hole 18 for each anchor shaft 9. Aligned to everyone Hole 18 is a bushing 4 below the coil core 6, which is fixed in the lower housing part 3 and the corresponding Anchor shaft 9 leads. The slots 19 act with corresponding Profiling of the inner wall of the lower housing part 3 together, so that recordings for the windings 8th result, as can be clearly seen in FIG. 3. By appropriate Openings project the connections 20 of the windings 8 to the outside, so that they are contacted and connected to the driver circuits can be connected. In the corners of the lower part of the housing 3 holes 17 are provided through which the stud bolts 58 run, the housing parts with each other and with the Connect the cylinder head 60 of the internal combustion engine.

The structure described on the one hand ensures that the housing underside 15 the available area on Cylinder head 60 optimally uses the internal combustion engine. Thereby can separate cooling of the multiple actuator omitted, since there is a large area for heat transfer between given lower housing part 3 and the cooled cylinder head 60 is.

The upper housing part 1 is analogous to that in FIGS. 2 and 3 assembled lower housing part 3 built. Between these the two housing parts 1, 3, the housing middle part 2 is arranged, the guide elements 19a, the longitudinal guide take over the anchor 10 (see FIG. 1). Through this A separate anti-twist device is not required because the Anchor 10 no longer that caused by the springs 12, 68 Rotation follows, which occurs when they are compressed.

Over the side walls of the housing, for example over the Side wall 16 (see FIG. 2) made of a good warming material, in this case aluminum, is a good one Heat transfer from the upper housing part 1 to in contact with the lower housing part 2 located with the cylinder head 60 possible. Thus, the one that arises in the upper electromagnet Heat loss well transported to the bottom 15 of the housing where they are through contact with the cooled cylinder head 60 is dissipated.

By arranging several anchor shafts 9 with their anchors 10 and the associated electromagnets in one housing the studs with which the housing parts 1, 2 and 3 with each other and these are attached to the cylinder head 60 move the outermost edge of the housing so that the armature 10 make optimal use of the available space. The gas exchange valves can be driven with maximum force.

Through the anchor guide by means of the guide elements 19a no separate guide side walls on the coil cores 5, 6 necessary, which is the pole face and thus that of the actuator would reduce applicable force. At the same time, the case falls more stable, and the coil cores 5, 6 are better too anchor.

In an alternative embodiment, the housing is in two parts executed. It is first made in one piece and a predetermined breaking point is grooved. Then the case turns on this predetermined breaking point broken into an upper and a lower part. Then the liners 4, the coil cores 5,6 as well as the windings 7, 8 and the armature shafts 9 introduced with the anchors 10. Then top and bottom reassembled, with a very high dimensional accuracy is achieved. In addition, the Heat transfer over this fracture surface due to its large size Gearing better than normal abutting surfaces. Finally there are no processing steps on the contact surfaces, thereby the manufacturing cost for the housing decreases.

To measure the stroke position of the armature 10 and that driven by it Valve plates 62 is the armature 9 through the liner 4 led out of the upper housing part 1. At anchor 9, a permanent magnet 50 is attached outside the housing. It is advantageous if the anchor shaft 9 from one largely non-magnetic material.

Near the permanent magnet 50 is on the top 14 of the housing by means of a holder 52 and screws 53 a magnetic field sensitive Sensor 51 attached. It is about around a giant MR sensor. But as a sensor 51 also working according to another principle, or a Combination of sensors possible.

The sensor 51 does not deliver its output signal cables shown in more detail to an evaluation electronics. His Output signal is only from the direction of the field lines of the dependent on the magnetic field generated by the permanent magnet 50, on the other hand not or only slightly from the field strength. Thereby can the position of the permanent magnet 50 and so the armature 10 and thus the valve plate 62 even with tolerances regarding the distance between permanent magnet 50 and sensor 51 or with respect to the field strength of the permanent magnet 50 can be determined safely.

Since a rotation of the armature shaft 9 through the anchor longitudinal guide the guide elements 19 is excluded is a separate one Protection against rotation is not necessary. To be on the safe side however, an annular permanent magnet 50 may be used, which is rotationally symmetrical to the axis of the armature shaft 9.

Of course, it is also possible to use several magnetic field sensitive devices Sensor 51 in an arrangement, e.g. a Wheatstone bridge or in a differential arrangement on an anchor shaft 9 to provide the position of a permanent magnet 50 determine.

In a modification of the concept according to the invention, the Permanent magnet 50 firmly connected to the sensor 51 be, and the valve stem 9 or a component attached to it made of soft magnetic or ferromagnetic material his. This material then moves relative to the sensor, which is in the air gap between the moving part and the Permanent magnet 50 is located.

All magnetic field-sensitive sensors 51 are preferably used by a protective cover 57 against magnetic and electrical Interference shielded (see Fig. 4). All magnetic field sensitive Sensors 51 of the multiple actuator are on a common power strip 56 connected through which it be contacted to provide them with energy and their Read out measurement signals.

Instead of the double actuators described here also more than two gas exchange valves from a single multiple actuator be operated. For example, it is possible, all valves on the inlet side of an internal combustion engine to drive with an actuator strip. For reasons of stability and to improve the guidance of the anchors then vertical partition walls are provided, which between the individual actuator parts or double actuators are.

Claims (20)

1. Electromagnetic multiple actuator, in particular for at least two gas flow valves of an internal combustion engine, with a housing (1, 2, 3) through which at least two armature shafts (9) pass, on each of which is secured an armature (10), whereby two electromagnets each having a coil core (5, 6) and a winding (7, 8) are provided for each armature, between which electromagnets the respective armature is located, and each armature (10) is acted upon in opposing directions by a first and a second spring (12, 68) to hold it in a neutral position between the electromagnets, whereby the first spring (12) in each case is mounted between a section (3) of the housing and an armature spring retainer disk (13) secured to the armature shaft (9).
2. Multiple actuator according to Claim 1, characterised in that the housing (1, 2, 3) has guide elements (19) on its inner sides, which guide the armatures (10) longitudinally on the axis of the armature shafts (9).
3. Multiple actuator according to one of the preceding claims, characterised in that the housing (1, 2, 3) is designed in such a way on at least one side wall (16) that good heat dissipation is achieved from the upper side of the housing (14) to the lower side of the housing (15) cooled by means of contact with a cooled part (60).
4. Multiple actuator according to one of the preceding claims, characterised in that each armature shaft (10) is guided in bushes (4) which are inserted into the upper and lower sides (14, 15) respectively of the housing.
5. Multiple actuator according to one of the preceding claims, characterised in that the first springs (12) are supported with respect to the housing on washers (11) which can be adjusted in the axial direction for setting the spring tension.
6. Multiple actuator according to one of the preceding claims, characterised in that the housing is in two parts and the two parts of the housing (1, 3) are joined together by way of bolts which pass through at least one side wall (16) of the housing (1, 2, 3).
7. Multiple actuator according to Claim 6, characterised in that the housing parts (1, 3) are manufactured by means of rupture separation of a single-part housing in order that the rupture point ensures that the housing parts fit.
8. Multiple actuator according to one of the preceding claims, characterised in that more than two armature shafts (9) are provided with an armature (10) and associated electromagnets, and that the housing (1, 2, 3) has a subdivision between two armatures and their electromagnets.
9. Multiple actuator according to Claim 8, characterised in that the subdivision has guide elements (19) which guide at least one armature (10) longitudinally on the axis of the armature shaft (9).
10. Multiple actuator according to one of the preceding claims, characterised in that a plurality of electromagnets has a common coil core (5, 6).
11. Multiple actuator for gas flow valves according to one of the preceding claims, characterised in that the second springs (68) are each mounted between a valve spring retainer disk (67) secured to the valve shaft (64) of the actuated gas flow valve and a cylinder head (60) in which the gas flow valves are guided.
12. Multiple actuator according to one of the preceding claims, characterised by a measuring device (50, 51) for each armature (10) with a permanent magnet (50) defined with respect to the armature (10) and a magnetic field sensitive sensor (51) defined with respect to the housing (1, 2, 3).
13. Multiple actuator according to Claim 12, characterised in that at least one of the permanent magnets (50) is secured to the associated armature shaft (9).
14. Multiple actuator according to one of Claims 1 to 11, characterised by a measuring device (50, 51) for each armature (10) with a construction component defined with respect to the armature (10) and a permanent magnet (50) defined in the housing (1, 2, 3) as well as at least one magnetic field sensitive sensor (51) defined with respect to the housing (1, 2, 3), whereby the sensor (51) is situated in the air gap between the construction component and the permanent magnet (50).
15. Multiple actuator according to Claim 14, characterised in that each construction component is made of magnetically soft or ferromagnetic material.
16. Multiple actuator according to one of Claims 12 to 15, characterised in that the output signal from at least one of the sensors (51) essentially depends only on the direction of the magnetic field.
17. Multiple actuator according to one of Claims 12 to 16, characterised in that at least one of the magnetic field sensitive sensors (51) has one or more of the following sensors: anisotropic MR sensor, Hall effect sensor, magnetoresistor, magnetorestrictive giant MR layer system.
18. Multiple actuator according to one of Claims 12 to 17, characterised in that at least one of the permanent magnets (50) is symmetrical with respect to the axis of the armature shaft (9).
19. Multiple actuator according to one of Claims 12 to 18, characterised in that at least one of the magnetic field sensitive sensors (51) is at least partially screened against electrical and/or magnetic interference fields.
20. Multiple actuator according to Claim 19, characterised in that the electromagnets are located in a housing, each armature shaft (9) projects out of the housing, and the permanent magnets (50) and the sensors (51) are located outside the housing.

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