EP0970298B1 - Electromagnetic valve drive mechanism - Google Patents

Description

The invention relates to an electromagnetic drive the features of the preamble of claim 1.

Such an electromagnetic drive is from DE 3616540 A1 known. There is one indirectly from an anchor driven lever directly with a valve to be driven coupled. Between the articulation point of the lever, which by a torsion spring is given, and the lever end that the Valve stem operated, is an operating rod with side play coupled with the anchor of the electromagnetic drive is connected and by this is driven. The actuation rod and thus the anchor are stored separately using a roller bearing.

From utility model 66 06 789.8 and from GB-PS-1524322 are electromagnetic vibration drives with a Spring bearing of the anchor is known. In the first Writing is the anchor on a one-sided clamp Leaf spring stored, in the other script is for storage a torsion spring is provided at the non-clamped end a rotating anchor is attached.

From GB-A-1471537 is an electromagnetic drive for a valve of an internal combustion engine is known, in which two Pairs of electromagnets two anchors alternating in two Bring end positions. The anchors are hinged on one side Lever trained. They work together on the shaft of one Valve. Without excitation a magnet represents one Spiral spring the drive in the one end position, in which the Valve is closed. Each lever only has one per end position a working pole. As a result, the power of the Magnet system for each lever only very low. A disadvantage of this drive is also that the entire magnetic flux over the Storage of each lever flows, which increases Bearing friction and thus a quick wear results.

The invention is based on the object electromagnetic drive of the type mentioned create that has a very low bearing friction and moreover due to a reduction in the moving masses as well as optimal power transmission with lower performance can be operated.

This task is characterized by the characteristics of the Claim 1 solved.

The solution according to the invention creates a simplified one low-wear bearing with little friction. So that is no permanent oil lubrication required either. In particular in that the lever is direct, i.e. without an intermediate part that carries electromagnetically movable part, become the acting Forces forwarded directly without fasteners, from where a mass reduction results, a smaller one Control power entails.

The drive is formed by two electromagnets, between whose poles turn on by alternately switching the excitation currents Anchor as an electromagnetically movable part back and forth is movable.

The construction is characterized in that the Anchor, without power consumption of the drive by spring forces is held in an intermediate position.

Further advantageous embodiments of the invention are in the Subclaims mentioned in connection with the Drawing description are highlighted.

A special weight reduction also results from the exclusive storage of the lever by means of the torsion bar according to claim 5, resulting from a weight saving improved efficiency of the drive results.

An optimal utilization of the acting forces results in a construction according to claim 6. In particular if this applies to the element to be driven, e.g. a valve acting actuator between the lever bearing and the is attached electromagnetically movable part, is due the lever ratios a reduction of the stroke e.g. of Anchor before.

The ratio is reduced accordingly required force and also the effective moving mass for Movement of a valve so that the drive is correspondingly smaller and can be dimensioned more easily.

Because of the smaller magnet volume, it is possible Magnetic circuit in the area of the magnetic yoke slightly larger dimension, from which advantageously less Iron losses result.

Drives also have advantageous effects with the features of claim 1, where to reduce the Movable masses actuator and element to be driven are directly coupled to one another or according to claim 9, because then e.g. by an elastic element, e.g. on Spring element valve and drive mass effectively from each other can be decoupled what is due to the acting Shock forces are advantageous. The spring element can e.g. as Abhubhubfeder be designed with a stop that the stroke of for example controlled valve or the armature limited. By having a high magnetic force corresponding to the gas forces, can e.g. with an exhaust valve higher gas forces to be dealt with.

In systems with a valve return spring, their Spring force in the closed state should be such that the Force is greater than the gas force of the exhaust back pressure. This requirement means a considerable additional weight. at a rigid coupling between armature and valve actuation can this momentarily acting gas force by the magnetic force be balanced. This means a significant one Weight savings.

There is a particular variability and possible application by the features of the further subclaims.

Exemplary embodiments of the invention are shown in the drawing explained in more detail.

Fig. 1

eine Drehstablagerung eines Ankers in einem Antrieb mit zwei Elektromagneten;

Fig. 2, 3

eine Drehstablagerung in zwei Ansichten mit einer Zwei-Stufen-Rückstellfederkraft;

Fig. 4

ein Diagramm zur Darstellung der Zwei-Stufen-Rückstellfederkraft gemäß den Fig. 2 und 3;

Fig. 5 und 6

zwei Ausführungsbeispiele mit einer Überhubfeder;

Fig. 7,8 und 9

Details der Überhubfeder;

Fig. 10

unterschiedliche Anordnungen einer Überhubfeder;

Fig. 11

den Einsatz einer Biegefeder statt Überhubfeder;

Fig. 12

die gegebenen Hebelverhältnisse zur Kraftoptimierung.

Show it

Fig. 1

a torsion bearing of an armature in a drive with two electromagnets;

2, 3

a torsion bar bearing in two views with a two-stage return spring force;

Fig. 4

a diagram showing the two-stage return spring force according to FIGS. 2 and 3;

5 and 6

two embodiments with an overtravel spring;

7,8 and 9

Details of the spring;

Fig. 10

different arrangements of an overtravel spring;

Fig. 11

the use of a spiral spring instead of an overstroke spring;

Fig. 12

the given leverage ratios for power optimization.

In Fig. 1 a torsion spring (torsion bar or rotary tube) storage shown in principle. At this Storage, the masses to be accelerated are very small. It a double magnetic drive is shown, which consists of magnetic cores 1 and 2 with magnetic poles 3 and 4 out on the cores wound windings 5 and 6 and an armature 7, that moves in the field of magnets.

When one of the electromagnets (1, 3, 5) or (2, 4,6) the anchor 7 is moved from the intermediate position shown (e.g. Middle position) towards the magnetic poles 3 or 4.

The magnetic poles 3 and 4 are formed obliquely to the Adapted to the course of the armature 1 rotated about the axis 10 his. The detailed structure of the torsion bar is shown in FIG. 3 removable. A torsion bar 30 is rigidly clamped here at 31. At the free end, there is one that allows twisting Support bearing 32, for example, a needle bearing or plain bearing is provided. With the torsion bar 30 is a bearing lever in the form of a cage 33 connected, which in turn receives the anchor 37. At this Cage 33 is also an operating rod by means of a bearing 29 rotatably mounted. The shaft 34 of the bearing is e.g. about a screw connection or rivets connected to the cage 33.

In Fig. 1, the axis 10 is the axis of rotation of the torsion bar. The Cage 33 of Fig. 3 can also in Fig. 1, the bearing lever 11 of the Anchor 7 be. The anchor 37 is e.g. in the cage 33 riveted. In Figure 3 are to the right and left of the Bearing shaft 34 to recognize the rivet pins.

In Figure 1 is with the armature 7 or the bearing lever 11 Actuating rod 12 rotatably connected via a bearing 13, the in turn via a coupling member 15 with e.g. a valve lifter 16 is connected. As a result, the lateral forces at Low stroke movement. In the example of FIG. 1, it is assumed that the torsion bar (in axis 10) the zero position of the armature causes itself, i.e. applies the entire spring force.

Fig. 2 corresponds to Fig. 1 with the difference that here the Restoring forces from the spring bar 20 and one Valve return spring 32 are formed and at a certain deflection in each direction Spring force increased. 2 this is additional Restoring force by a clamped at the right end Leaf spring pair 23/24 and an extension 25 of the armature 21 realized that an additional a certain deflection the leaf springs 23 or 24 must bend. This is also shown in Fig. 3 in a different view.

4 shows the course of the sum of the 2 and 3 shown two-stage return spring. This two-stage spring has the advantage that the spring characteristic is better adapted to the magnetic force curve FM. Therefore, it can System already from the rest position without the usual Start-up process to be moved to the end position. About that In addition, the steep spring characteristic of the second one Spring a correspondingly high deceleration of the opposite end position arriving anchor, which is significant contributes to damping and position control. Continue wearing the possible high final force of the spring to a high Initial acceleration and thus quick valve opening.

5 is for storing a Anchor 50 a torsion bar 52 is provided which the torsion bar 20 Fig. 2 corresponds. The torsion bar 52 is by means of a Bearing lever 51 connected to the armature 50 so that the armature by two electromagnets (magnetic circuit 53 and 55 and Windings 54 and 56) can be moved up or down. Here, too, the torsion bar generates both spring forces.

An actuating rod 57 is articulated on the bearing lever 51, by means of an overtravel spring 58 with a valve tappet 59 connected is. By means of this overtravel spring 58, the valve is closed moved with an anchor movement.

By using the overtravel spring 58 is compared to the direct coupling e.g. 1 a large one Load on the valve seat due to the mass force of the valve and avoided anchors.

This also enables better end position control. Here too, brief valve openings are caused by a Avoid regulation at the stop.

On the magnetic circuit 53 and the magnetic circuit 55 are in addition to the Windings 54 and 56 still further holding windings 60 and 61 arranged, the armature 50 during their control in the hold the corresponding end position.

6 differs from FIG. 5 in particular in that that the armature 70 in its end positions by a locking roller 71 and is not held by a holding current. The Locking roller 71, which in Fig. 6 under one with the armature 70th connected locking plate 72 is engaged to trigger the armature movement down by a locking magnet 73 and an associated rocker 75 rotatable about an axis 74 the locking roller is mounted, out of the latch emotional.

The torsion springs now accelerate the armature 70 down and a current pulse on the lower coil brings the armature finally to the other end position. The rolls on the Bracket 74 mounted locking roller along the locking plate 72 to it engages again in the other end position. The Locking magnet 73 and the holder 75 are against by one Force of the locking magnet directed spring not shown in the position shown.

5 and 6, the actuating rod 57 is not hinged directly to the armature 50 but to the bearing lever 51. This is the way of the armature and the valve differently. The end of the operating rod 57 is in the middle position on the valve stem head.

In Fig. 6 it is assumed that the engine is warm. The Residual air gap 76 is small here because the overtravel spring without Stop a corresponding anchor movement regardless of the Allows valve expansion, so that the locking roller 71 engages.

5, however, a cold engine is assumed. Here will the overtravel spring 58 effective after the closing of the Valve 59 is bent and as a result of large gas forces the magnetic force is pressed onto the stop. Remains here a larger residual air gap 67, which is dependent on Valve expansion and valve wear.

In Figures 7, the over-travel spring, its attachment and the stop drawn out in detail, Fig. 7b a Side view and Fig. 7a a view seen from the right shows. The operating rod is at 87, the valve stem at Designated 89. The overtravel spring 88 is with the Actuator rod 87 connected and engages in a fork shape Groove of the valve lifter 89. In Fig. 7b is in the upper part e.g. welded stop (85.86) can be seen. Parts 85, 86, 87 can consist of one piece.

When the overtravel spring 88 is bent open, the fork comes Lift spring with the lower ends of parts 85 and 86 Stop, so that further bending is no longer possible is.

Drawn in is a resilient fork-shaped Centering element 84, which the actuating rod 87 on the Valve stem 89 centered.

In Fig. 8 it is indicated that the overtravel spring is redundant can produce 90 from two springs.

Finally, in Fig. 9 is a spring 98 with an envelope 99 shown, which acts as a catch plate and causes that at a break in the overtravel spring 93 over the stop can be moved into the closing end position without hitting on the piston.

The use of a redundant spring 90 brings high Reliability. The use of the enveloping spring enables closing and shutdown in an emergency Valve.

The overtravel spring can, as shown in FIG. 10, also between the Actuating rod 107 and the connecting part 101 arranged his. The stop is here by a pin 103 and a Elongated hole 102 causes. 10 shows another Adjustment screw 104, with which the distance, i.e. the Valve play between the operating rod and valve lifter, the Coupling is stiff here, can be adjusted.

Fig. 11 shows an example in which the Actuating rod 117 via a spring 118 with the bearing lever 111 is connected. The spring 118 is one here Leaf / spiral spring. This is a wear-free joint possible, with a kink protection for the spiral spring 118 can be provided.

As an alternative to FIG. 11, the actuating rod 117 could be by means of of a leaf spring joint to be articulated on the bearing lever 111.

5, 6, 10 and 11 it was shown that the Operating rod between the turning center and the anchor center can articulate.

The aim of this is the driving force of the electromagnetic Drive increase to either this higher force or to use the magnets while maintaining the same force out.

This design is particularly advantageous for the reduction the moving masses, where the anchor is a relative has a large share. Here it decreases linearly with increasing Leverage ratio the effective mass.

The gear ratio is used here. This Training is particularly important when using the electromagnetic actuator for valve control of Internal combustion engines are an advantage because of the great power in them the end positions and the air gap of the armature is not is dominant.

12, the torsion bar is shown schematically at 120. The bearing lever 121 is shown as a line; the anchor bears the reference numeral 122, the actuating rod the reference numeral 123. The actuating rod 123 is now connected at a distance 11 from the bearing point 120 to the bearing lever 121, while the center of the armature is 12 away therefrom. The magnetic force FM is shown as arrow 124. The force FR acting on the actuating rod 123 is calculated as: FR = FM 12/11 It is increased by the gear ratio 12/11 while the magnet size remains the same.

In Fig. 2, the spring forces acting on the armature were by the torsion bar spring 20 and the spring 22 are generated. However, it is also possible the torsion bar spring forces two against each other directional torsional forces to superimpose higher To generate restoring forces.

The electromagnetic drive described above can Driving a gas exchange valve or another comparable valve can be used. One can also use it Pump driven, the valve lifter by a Pump piston is replaced.

But it can also be used in gearboxes because it is there a quick switch from one to the other Position with high strength is desired. Also with others Applications with similar requirements is the invention used.

Claims (21)

1. Electromagnetic valve mechanism with two electromagnets (1, 2) and with an anchor running on bearings, able to move to and fro between the pole faces which when one of the electromagnets is switched on is brought to one of the two end positions, whereby a valve of a combustion engine is operated as a result of the movement of the electro-magnetically controllable anchor (7, 27, 37, 50, 70) and whereby a lever (11, 21, 33, 51) linked at one end directly supports the anchor (7, 27, 37, 50) without any intermediate part, characterized in that the anchor (7, 27, 37, 50) when the electromagnets (1, 2) are switched off is brought by spring force into an intermediate position and held there, and that the lever (11, 21, 33, 51) is connected with a torque rod or tube (10, 20, 30) and the link of an operating element (12, 22, 57) allows it to turn on the anchor (7, 27, 37, 50, 70) or on the lever (11, 21, 33, 51) and that this operating element (12, 22, 57) acts on the valve and that the two poles in each case of one electromagnet (1, 2) in each case form an end position for the anchor or lever.
2. Electromagnetic mechanism according to claim 1, characterized in that the lever forms a frame or cage (33) which surrounds the electro-magnetically controllable anchor.
3. Electromagnetic mechanism according to one of the above claims, characterized in that the torque (30) is held in a support bearing (32).
4. Electromagnetic mechanism according to one of the above claims, characterized in that the torque rod axis is arranged vertically to the movement direction of the driven part (59).
5. Electromagnetic mechanism according to one of the above claims, characterized in that the rotary rod (10, 20) is the only bearing for the lever (11, 21).
6. Electromagnetic mechanism according to claim 5, characterized in that the operating element (12) is fastened to the anchor (7).
7. Electromagnetic mechanism according to claim 6, characterized in that the operating element (57) is fastened to the lever (51) between the lever bearing (52) and the anchor (50).
8. Electromagnetic mechanism according to one of the above claims, characterized in that the link of the operating element (12, 22, 57) allows it to turn by means of a roller bearing (29) on the anchor (7, 27, 37, 50, 70) or on the lever (11, 21, 33, 51).
9. Electromagnetic mechanism according to one of the above claims, characterized in that a spring element (88) is provided to connect the operating element (87) and the element to be driven (89).
10. Electromagnetic mechanism according to claim 9, characterized in that at least one other spring lies parallel to the spring element (90).
11. Electromagnetic mechanism according to claim 9, characterized in that to the spring element (90) is an over lifting spring.
12. Electromagnetic mechanism according to claim 11, characterized in that the over lifting spring (98) comprises a sheathe spring (99).
13. Electromagnetic mechanism according to one of claims 11 or 12, characterized in that a stop (85, 86) is provided for maximum compression of the over lifting spring (88).
14. Electromagnetic mechanism according to one of the above claims, characterized in that a centering element (84) is provided for aligning the operating element (87) to the valve shaft (89).
15. Electromagnetic mechanism according to one of the above claims, characterized in that a spring element (108) is arranged between the lever (101) and the operating element (107).
16. Electromagnetic mechanism according to claim 15, characterized in that the spring element (108) is designed as over lifting spring.
17. Electromagnetic mechanism according to claim 15, characterized in that the spring element is designed as spiral spring (118).
18. Electromagnetic mechanism according to one of the above claims, characterized in that at least one additional spring force pair (24, 25) reinforcing the reset action is effective after a certain excursion of the electro-magnetically controllable part (27) out from the intermediate position.
19. Electromagnetic mechanism according to one of the above claims, characterized in that the operating element (107) comprises an adjustment screw (104) to adjust its length.
20. Electromagnetic mechanism according to one of the above claims, characterized in that the anchor (70) is held firm in the end positions by mechanical locking (71 to 75) which is electro-magnetically controllable.
21. Electromagnetic mechanism according to one of the above claims, characterized in that the anchor (50) can be held firm in the end positions by electromagnetic retaining excitation (60, 61)

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