DE102012213180B4 - Linear actuator and valve actuator - Google Patents

Abstract

Electromagnetic, linear actuator for activating a gas exchange valve, the actuator being formed from a fixed part (5, 1) and a linearly movable part (2, 3) and the fixed part (5, 1) at least one housing (5, 25) and a first coil (1) fastened in the housing (5, 25) and the movable part (2, 3) has at least one plunger (3) and a second coil (2) fastened on the plunger (3) , whereby both coils (1, 2) are arranged concentrically around the plunger (3) and, when energized, the second coil (2) axially approaches the first coil (1) and / or moves at least partially into it and on the plunger (3) a movement damper (6) is attached, which is provided for interaction with a movement-limiting element (23).

Description

The invention relates to an electromagnetic, linear actuator for activating a gas valve, wherein the actuator is formed of a fixed part and a linearly movable part. Furthermore, the invention relates to a valve actuating device with such an electromagnetic, linear actuator.

Such an actuator is used in internal combustion engines that do not require a camshaft and whose gas valves are controlled by the electromagnetic actuators and a control electronics in the sense of the known engine operation. Thus, rotating, weighty mechanical parts are replaced by the actuator with control electronics, which in addition to a weight advantage and a space advantage in the engine compartment of a vehicle arise.

The valves, as described in the patent EP 1 170 489 B1 are disclosed are actuated by means of actuators which are arranged on the cylinder head, and thus the internal combustion engine operated optimally.

Solenoid valves for this application are also from the DE 197 35 375 C1 or the US Pat. No. 6,810,841 A1 known. Therein, the magnetic function of energized coils is used such that a magnetizable metal plate, which is connected to the gas exchange valve, between two positions within the magnetic switch can be switched back and forth. The two positions thus correspond to a valve opening or a valve closure.

The problem with the already known solutions is that, given the required actuating force, the actuating units assume a considerable size, which unfavorably fills the space around the cylinder head. However, a minimum required operating force does not allow further reduction of this unit.

An electromagnetic linear actuator of the type mentioned is from the DE 10 2011 080 065 A1 known.

The invention has for its object to provide an actuator or a valve actuating device which applies a high actuation force and yet requires only little space.

This object is achieved by an actuator having the features specified in claim 1 or by a valve actuating device according to claim 8.

According to the electromagnetic linear actuator for actuating a gas valve from a fixed part and a linearly movable part is formed. In this case, the fixed part has at least one housing and a first coil mounted in the housing. Furthermore, the movable part has at least one plunger and a second coil mounted on the plunger. By a corresponding energization, the first and second coils interact electromagnetically, so that an actuation or a linear movement is caused. The first coil is mounted in the housing, which in turn is mounted in the engine compartment, in particular in the vicinity of the cylinder head. When energized, therefore, the second coil and everything attached to it is forced to move linearly. Thus, the second spool in particular drives the plunger with which it is connected in order to achieve an actuation of the gas exchange valve connected to the plunger.

The two coils are arranged concentrically around the plunger. When energized, the second coil approaches axially to the first coil or is even partially drawn into this. In the case of opposite energization, a return movement may possibly also take place.

In an advantageous embodiment, a restoring element, in particular a spring, builds up a restoring force when energized, in order to move the movable part relative to the fixed part into an initial position. In other words, when energized, the movable part moves with the plunger in the actuated position to get back to the starting position with decreasing or dropping current. This would not require a counter current to the return movement of the movable part.

Advantageously, the housing is at least partially or entirely made of deep-drawn metal. Deep-drawn metal can be cold formed and is much easier to use for the manufacture of the housing, ie auszustanzen or otherwise transform. In addition, the performance characteristics of the actuator can be improved because the material used is very thin-walled and thus more space for the coils and the plunger remain. This applies in particular to the radial direction, in which both coils can occupy more space in the respective housing part radially outwards and thus contribute significantly to an increase in operating force. As already indicated above, it is advantageous to allow only one direction of movement during energization. For such embodiments, it is again preferred if the movable part has a motion damper, in which, for example, the motion damper is mounted on the plunger, wherein the Movement steamer is provided for interaction with a movement-limiting element. The movement-limiting element is attached directly or indirectly to the housing of the actuator, and absorbs the kinetic energy of the plunger, unless it is already braked down by the gas valve to be actuated, so that a further deceleration would no longer be required. Thus, the movement-limiting element also limits the actuation path of the actuator. It is advantageous that both the motion damper and the motion-limiting element can be arranged substantially in the coil interior of the first coil and thus further save installation space.

The movement-limiting element may at least partially comprise a bearing of the plunger. The plunger could be roller-mounted with respect to the housing, so that it is already movable from its initial position into the actuated position with the lowest possible magnetic force. In this way, the static friction can be largely reduced.

It is definitely advantageous if the first coil at least partially encloses the movement-limiting element and / or the motion damper so that the interior of the first coil can be utilized optimally.

In a preferred embodiment, the motion damper is widened in the interaction with the movement-limiting element perpendicular to the actuation direction of the plunger. This leads to an elastic stress of the motion damper, whereby the kinetic energy is convertible into deformation energy and thus slows down the moving part, in particular the plunger, to a standstill.

In a conical design of the movement-limiting element, a further advantage arises because the elastic constant due to the conical structure is changeable to the effect that with increasing elastic stress, the transformation of the kinetic energy faster, d. H. with shorter braking distance, in elastic deformation energy is accomplished. Alternatively, this could only be accomplished by a greater accumulation of elastic material on the muffler, but this material would take up a great deal of space. The cone thus replaces a larger amount of material on the moving part.

Thus, the valve operating device according to the invention without camshaft can now be implemented with a lever rotatable about an axis and an actuator according to the invention. In this case, a first, long lever piece with respect to the axis of the plunger operable and a second, short lever piece with respect to the axis for actuating the gas exchange valve is provided. Long or short lever piece in this case means that the first lever piece represents the longer lever piece compared to the second lever piece. Both lever pieces or their length ratio also define the ratio of the lever-reinforced actuating force of the gas valve to the actuating force of the actuator.

Advantageously, said lever is made of two metal strips which are fastened to each other. The axis of rotation may be attached to a location of the lever where it separates both metal strips from each other. At this point axle and metal strips can be fastened together, such. B. via a weld or a common deformation. The two end pieces of the lever each define the beginning of the first and second lever piece, both of which end at the axis.

Further advantageous embodiments and preferred developments of the invention can be taken from the description of the figures and / or the dependent claims.

The invention will be described and explained in more detail below with reference to the embodiments illustrated in the figures.

Brief description of the figures

Show it:

1 an electromagnetic actuator in longitudinal section along the actuating plunger,

2 a valve operating device with a lever, linear actuator and electronic control, and

3 the lever off 2 ,

Detailed description of the figures

1 shows the linear electromagnetic actuator in a sectional view. The housing 5 . 25 The actuator consists of two housing parts 5 . 25 , wherein the first housing part 5 the first coil 1 receives and the second housing part 25 the second coil 2 takes up, the coil 2 is shown in its initial position. Both housing parts 5 . 25 are by riveting 11 attached to each other. Here also alternative attachment methods, such. As screws or bolts can be used.

The return spring 10 is by means of fastening 8th on the second coil 2 fixed so that when decreasing energization of the coil 2 along with the pestle 3 and the motion damper can be brought back into the illustrated starting position. In this (pictured) starting position is the return spring 10 not biased.

At each translation of the moving part coming out of the ram 3 , the motion damper 6 and the coil 2 is the moving part by means of a rolling bearing 9 opposite the second housing part 25 stored, or shifted friction. During translation, the gap becomes 7 if necessary for storage 9 used.

Due to the thin wall of the second housing part 5 , in particular in the cylindrical region, the radial extent of the second coil 2 be significantly increased, whereby a higher magnetic flux density, a higher actuation force of the actuator is achieved.

The second coil 2 can, thanks to the storage 9 , almost completely into the coil interior of the first coil 1 to be moved.

If, in such an operation, the actuating force to be applied to the gas valve is not enough to stop the moving part, the interaction of the movement limiting element will be insufficient 23 with the motion damper 6 the movement of the moving part is finished.

The movement-limiting part 23 has a conical outer shape, which is substantially in hollow cone segment of the motion damper 6 fits. However, the outer cone of the movement-limiting element acts 23 nevertheless on the movement damper 6 structurally expanding in the radial direction. From this expansion elastic counterforce is applied, which allows to store a lot of elastic energy and thus destroy kinetic energy.

The motion damper 6 further includes a cylindrical mounting member which is press fit on the plunger 3 is arranged while still a part of the second coil 2 bordered, which is partially also included radially end.

Advantageously, a further storage 4 of the plunger 3 in the movement-limiting element 23 arranged where they are unlike storage 9 the second coil 2 opposite the housing 5 . 25 tight.

2 shows a valve actuator with the lever 12 and the actuator off 1 , The gas valve 14 is at the shorter lever piece 31 or attached to the end. The lever 12 performs an angle-limited rotation about the axis of rotation 23 out by the extension 13 of the plunger 3 on the end of the longer lever piece 30 acts, with which it is connected at the end.

The second housing part 25 can if the first housing part 5 in the cylinder head can be inserted, are designed as a lid. It is important that the actuation force, which is optimized by the already already actuation force optimized linear electromagnetic actuator, can be reinforced by the lever again.

In the embodiment of 2 is a ratio of 1: 2 from the shorter lever piece 31 to the longer lever piece 30 in front. Consequently, on the gas valve 14 a force is applied which is substantially twice as strong as the actuating force of the plunger 3 of the actuator 1 ,

It is also advantageous that the lever 12 is designed as a lightweight lever and consists of two metal strips, which is the axis of rotation 23 between them, which alone due to the metal strip deformation no further fasteners that would contribute further weight, are required. In addition, the bipartite nature of the lever 12 to a length stiffness, which is advantageous for power transmission.

Due to the use of the lightweight lever 12 it is no longer necessary to settle the actuator directly on the cylinder head, which is a further space option is given.

So that a camshaft can be completely replaced, now the linear actuators must be controlled by means of control electronics such that the engine runs optimally. The omission of the camshaft leads to a significant weight savings and thus also to a significant fuel economy, especially since the camshaft belongs to the moving parts of the engine. In addition, electrical control systems have become very inexpensive in recent years, so that hydraulic systems may soon be replaced by electromagnetically linear actuated systems.

The supply lines 22 include two wires to the power supply unit 15 coming from the battery 17 and two other supply lines that provide the linear actuator with control information. The control unit is via a sensor bus 21 with sensors 19 . 20 on the crankshaft 18 which, using the electrical control system, allow the optimum current time for motor operation to be set or calculated. For example, sensor could 19 a speed sensor that measures the angular velocity of the crankshaft. Accordingly, it could be at sensor 20 to act a position sensor, which can indicate the position of the piston in the cylinder as a function of time.

3 shows the lever arm 12 with its enclosed axis of rotation 23 , with the ends of the lever 12 each with the ram extension 13 or is coupled to the gas valve, wherein the return spring 8th ensures a return movement of the gas exchange valve in its starting position.

In summary, the invention relates to an electromagnetic, linear actuator and a valve actuator with a lever and the said actuator, wherein both the device and the actuator are weight-reduced and in conjunction with an electronic control system are able to operate an internal combustion engine without a camshaft. The increased operating force is caused on the one hand by a design of the housing or the housing parts of the actuator from deep drawn sheet metal parts, which remains for the first and second coil of the actuator more space and thus a stronger magnetic interaction can take place during actuation. Further, a lever is proposed, which is to be provided for coupling the plunger with the gas exchange valve and causes an increase in the actuation force via a corresponding translation. Furthermore, there is the advantage that the linear actuator does not have to be arranged directly on the cylinder head. In addition to a large weight savings due to the lack of camshaft can also be benefited by a fuel economy, since there are few moving parts.

LIST OF REFERENCE NUMBERS

1

first coil

2

second coil

3

tappet

4

storage

5

first housing part

6

motion damper

7

gap

8th

spring mounting

9

storage

10

Return spring

11

rivet

12

lever

13

ram extension

14

Gas exchange valve

15

power supply

16

control unit

21

Sensorbus

17

battery

18

crankshaft

19

speed sensor

20

position sensor

22

Aktuatorbus

23

axis of rotation

25

second housing part

Claims (9)

Electromagnetic, linear actuator for activating a gas exchange valve, wherein the actuator consists of a fixed part ( 5 . 1 ) and a linearly movable part ( 2 . 3 ) and the fixed part ( 5 . 1 ) at least one housing ( 5 . 25 ) and one in the housing ( 5 . 25 ), first coil ( 1 ) and the movable part ( 2 . 3 ) at least one plunger ( 3 ) and one on the pestle ( 3 ) attached second coil ( 2 ), both coils ( 1 . 2 ) concentrically around the plunger ( 3 ) are arranged and when energized, the second coil ( 2 ) axially to the first coil ( 1 ) approaches and / or at least partially moves into it and wherein on the plunger ( 3 ) a motion damper ( 6 ) for interaction with a movement-limiting element ( 23 ) is provided. Actuator according to claim 1, wherein a return element ( 10 ), in particular a spring ( 10 ), a restoring force during energization builds up around the moving part ( 2 . 3 ) in relation to the fixed part ( 5 . 1 ) to move to a starting position. Actuator according to claim 1 or 2, wherein the housing ( 5 . 25 ) is at least partially or entirely made of deep-drawn metal. Actuator according to claim 1, wherein the movement-limiting element ( 23 ) a storage ( 4 ) of the plunger ( 3 ) at least partially. Actuator according to claim 1, wherein the first coil ( 1 ) the movement-limiting element ( 23 ) and / or the motion damper ( 6 ) at least partially. Actuator according to claim 1, wherein the motion damper ( 6 ) in the interaction with the movement-limiting element ( 23 ) perpendicular to the direction of movement of the plunger ( 3 ) is widened. Actuator according to claim 6, wherein the movement-limiting element ( 23 ) is conical. Valve operating device with one around an axis ( 23 ) rotatable lever ( 12 ) and an actuator according to one of the preceding claims 1 to 6, wherein a first, long lever piece ( 30 ) in relation to the axis ( 23 ) from the ram ( 3 ) and a second, short lever piece ( 31 ) in relation to the axis ( 23 ) for actuating the gas exchange valve ( 14 ) is provided. Valve operating device according to claim 8, wherein the lever ( 12 ) is made of two metal strips which are fastened to each other and through the axis ( 23 ) are separated from each other at one point.

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