electromagnetic actuators

Abstract

The proposal relates to an electromagnetic actuator comprising an armature movable in an armature chamber along an axis, a magnetic coil for generating a magnetic field for moving the armature, a control element coupled to the movement of the armature, and a magnetic flux guide arranged at an axial end of the magnetic coil with an axially extending recess in which the control element is movably arranged, wherein the magnetic flux guide is constructed in two parts. It is proposed that the magnetic flux guide is constructed in two parts of a base part facing the armature and a head part facing away from the armature, and the control element is supported in a first bearing site constructed at the head part and in a second bearing site constructed at the base part in a manner movable along the axis.

Description

Technical Field

[0001] This invention relates to an electromagnetic actuator. Background Technology

[0002] Automatic transmissions in motor vehicles are known to use hydraulically operated clutches for gear shifting. To ensure that gear shifting occurs without sudden shocks and imperceptibly to the driver, it is advantageous to set the hydraulic pressure on the clutch with the highest possible accuracy according to a predetermined pressure ramp. For this purpose, it is known that the necessary pressure is provided by means of a hydraulic spool valve. The spool valve can be operated either via a pilot valve or directly via an electromagnetic actuator. In the latter case, the mechanical connection between the electromagnetic actuator and the hydraulic clutch section is crucial. It must be ensured that the high acceleration and running forces occurring in the automatic transmission during operation are absorbed without damage by the fixed structure of the electromagnetic actuator. Furthermore, it is important to position the movable actuating element of the actuator extremely accurately relative to the hydraulic system, as this determines the position of the hydraulic spool valve piston, operated by the actuating element, relative to the control edge of the hydraulic control mechanism. If this position is heavily skewed with tolerances, it is possible that the spool valve will shift into an undesirable position, resulting in either excessively high or low flow rates in the hydraulic lines.

[0003] The mechanical connection of the electromagnetic actuator has been proven to meet these requirements, with an annular slot arranged in the flux guiding section of the actuator. In the automatic transmission, a spring plate is fitted into this slot, supported on the outer wall of the hydraulic control mechanism, and the electromagnetic actuator is pressed against a reference surface within the hydraulic control mechanism, thereby positioning the actuator.

[0004] An electromagnetic actuator, for example, is known from DE 10 2012 223 430 A1, comprising: an armature movable in an armature chamber along a longitudinal axis; a magnetic coil extending around the longitudinal axis for generating a magnetic field to move the armature; an actuating element coupled to the armature's movement; and a flux disk body disposed at the axial end of the magnetic coil, having a groove extending along the longitudinal axis, in which the actuating element is movably supported. The flux disk body serves, on the one hand, to guide the magnetic flux. On the other hand, it is a mechanical interface with an actuator loaded by the actuated element, which, for example, can be configured as a spool piston guided within the valve body of a hydraulic valve.

[0005] Furthermore, a similarly constructed electromagnetic actuator is known in DE 10 2016 224 288 A1. This electromagnetic actuator also includes: an armature movable axially within an armature chamber; a magnetic coil for generating a magnetic field to move the armature; an actuating element coupled to the armature's movement; and a flux guiding portion disposed at the axial end of the magnetic coil, the flux guiding portion having an axially extending groove in which the actuating element is movably disposed. However, DE 10 2016 224 288 A1 does not describe a one-piece flux guiding portion, but rather a two-part flux guiding portion with a base connected to the flux disk by a slotted connection. The advantage of this is that the base can be manufactured by sintering without machining. However, the load-bearing capacity of the slotted connection is limited. Summary of the Invention

[0006] This invention describes an electromagnetic actuator comprising: an armature movable along an axial direction within an armature chamber; a magnetic coil for generating a magnetic field to move the armature; an actuating element coupled to the armature's movement; and a flux guiding portion disposed at an axial end of the magnetic coil, having an axially extending groove in which the actuating element is movably disposed. According to the invention, the flux guiding portion is constructed of a base portion facing the armature and a head portion facing away from the armature, and the actuating element is supported axially in a first bearing portion at the head portion and a second bearing portion at the base portion.

[0007] In the context of this application, "drilling" refers to a slightly elongated, cylindrical channel or channel segment, regardless of the manufacturing method.

[0008] Axial direction refers to a direction that extends parallel to or coincidentally parallel to the longitudinal axis of the actuator. The longitudinal axis of the actuator is formed by the axis of the central axis of the coil of the electromagnet, which preferably coincides with the central axis of the sliding actuating element.

[0009] Radial refers to any direction perpendicular to the axial direction.

[0010] The electromagnetic actuator according to the invention has a flux guiding portion that can be manufactured cost-effectively and without a costly production process. This flux guiding portion can be easily fitted with a fixing groove for mechanical fixation to a hydraulic system. The flux guiding portion is constructed of two parts, which can be connected to each other by a simple joining method, thus forming the fixing groove between them. The base portion and the head can be advantageously designed with only two demolding directions, allowing both parts to be manufactured without machining using a cost-effective sintering process. Both parts are therefore made of sintered steel, which meets both magnetic requirements and possesses high strength, heat resistance, and geometric precision.

[0011] Unlike existing technologies, the support structure of the actuating element according to the invention is divided into a first bearing portion in the base portion and a second bearing portion in the head. By dividing the two bearing portions according to two members that engage with each other, the bearing diameter at the member where the bearing is constructed in only one member is avoided from shrinking when the other member is pressed against by deformation forces that occur under adverse conditions. The length of the axial extension region of each bearing portion can be advantageously chosen to be shorter than that of solutions known in the prior art, thus excluding the increased manufacturing tolerances at the bearing diameter. The bearing clearance of the actuating element can therefore be constructed to be small, which has a positive effect on the sliding characteristics and prevents the danger that foreign objects may enter the interior of the electromagnet through excessive bearing clearance and cause malfunction there.

[0012] Advantageous embodiments and extensions of the invention are achieved by means of the features described in the dependent claims.

[0013] The recess for accommodating the actuating element can advantageously be formed by a first borehole extending axially in the head and a second borehole extending axially in the base portion, connected to the first borehole. The two boreholes can be manufactured independently of each other in the head and base portions. The two portions are assembled together by a subsequent joining process such that the first and second boreholes are collinear, that is, the central axes of the two boreholes are oriented such that their central axes lie on a common straight line.

[0014] Specifically, it is possible that the first borehole in the axially extending region of the first bearing portion has a first inner diameter configured to be smaller than the inner diameter of the first borehole in the region outside the first bearing portion, and / or the second borehole in the axially extending region of the second bearing portion has a second inner diameter configured to be smaller than the inner diameter of the second borehole in the region outside the second bearing portion. This ensures that the sliding support of the actuating element is achieved through the two narrow points of the groove in the regions of the two bearing portions and not through the inner wall of the borehole outside the bearing portion.

[0015] It is particularly advantageous that the first bearing portion in the first borehole is located at the end of the head that is away from the base portion, and the second bearing portion in the second borehole is located at the end of the base portion that is away from the head. This achieves a large distance between the two bearing portions, which causes the lateral force acting on the actuating element to result in only a slightly excessive bearing lateral force (the excessive force caused by the "cantilever effect" is reduced).

[0016] In particular, it is likely that the length of the axially extending region of the first bearing portion is less than three times the first inner diameter and / or the length of the axially extending region of the second bearing portion is less than three times the second inner diameter. Based on their small lengths, the bearing portions can be advantageously manufactured with extremely high precision. The risk of forming errors in the bearing portions (e.g., "banana shape") can be advantageously avoided, and extremely small bearing clearances can be selected. Small bearing clearances further reduce the risk of foreign matter intruding into the electromagnet and causing interference there.

[0017] The head of the flux guiding section can advantageously have a protrusion facing the base portion, which is engaged and secured within a receiving portion of the base portion. The head can, for example, have a disc-shaped section facing away from the base portion, and a cylindrical section forming the protrusion, having a smaller diameter than the disc-shaped section, protrudes from the disc-shaped section toward the base portion. The protrusion can, for example, be engaged within the cylindrical inner wall of the receiving portion of the base portion, thus orienting the head relative to the base portion in its radial position about the longitudinal axis of the actuator. The engagement of the base portion and the head creates a circumferential retaining groove between the disc-shaped section and the head, the bottom of which forms the outer wall of the protrusion. The protrusion can be secured in the receiving portion, for example, by force-fit or material fit. This can be accomplished, for example, by screw connection or welding. Alternatively, the protrusion can be pressed into the inner wall of the receiving portion. The press-fit connection between the protrusion and the receiving portion can advantageously have a large overlap length, thus achieving a large connection force. The joint between the two components is advantageously located in a region between the two bearing sections. This ensures that the extrusion process does not cause the bearing section to shrink or narrow in diameter.

[0018] In an advantageous embodiment, at least one axially extending longitudinal channel is provided in the support region of the face sections of the protrusion and the receiving portion facing each other. This at least one longitudinal channel can be constructed in a simple manner, for example, as a longitudinal groove or a diameter-flattened structure at the outer sheath of the protrusion and / or on the inner wall of the receiving portion of the base portion.

[0019] The first end of the longitudinal channel can, for example, extend into an annular groove for fixing the actuator at the end of the base portion facing the head, while the second end of the longitudinal channel is connected, for example, to a groove accommodating the actuating element through a gap between the base portion and the head. The longitudinal channel advantageously achieves pressure reduction because it hydraulically connects the region of the groove between the two bearing portions of the actuating element to the annular groove constructed at the flux guiding portion.

[0020] Pressure reduction can be an advantageous additional measure to reduce contaminant input into the electromagnet. If, for example, a hydraulic pressure greater than the pressure in the (normally unpressurized) internal space of the magnet is applied at the coupling point between the valve piston and the actuator's operating element during operation of the electromagnet, a small but continuous flow of hydraulic fluid into the internal space of the magnet may occur, resulting in some contaminant input. This small flow can be advantageously guided into the stationary groove by means of pressure reduction in the longitudinal channel. Attached Figure Description

[0021] Possible embodiments of the present invention will now be explained with reference to the accompanying drawings.

[0022] Figure 1 A schematic cross-section of a first embodiment of the electromagnetic actuator according to the invention is shown; Figure 2 It shows Figure 1 Enlarged detail photos show the grooves that house the control elements; Figures 3a to 3c In separate ( Figure 3a , 3b ) and the connection ( Figure 3c The status shows Figure 1 The head and base of the flux guiding section; Figure 4a and 4b The attached base portion with a magnetic flux guiding section is shown. Figure 4a The electromagnetic actuator according to the present invention ( Figure 4b A schematic cross-section of the second embodiment of ). Detailed Implementation

[0023] Figure 1 A cross-section of one embodiment of an electromagnetic actuator 1 is shown, which can be used, for example, as a spool valve for driving a hydraulically controlled gear clutch.

[0024] As in Figure 1As can be seen, the electromagnetic actuator 1 includes an electromagnet 2, which is configured, for example, as a proportional magnet and consists of a magnetic coil 4 and an armature 5, and preferably has a magnetic pole tube 3 inserted into the magnetic coil 4. The magnetic coil 4 has a coil body carrying the coil winding, which is configured, for example, to be rotationally symmetrical with respect to the longitudinal axis 101 of the actuator 1. The electromagnetic actuator has, for example, an electrical connector 21 for the magnetic coil 4 protruding radially from the longitudinal axis 101. The aforementioned pole tube 3 is arranged in the magnetic coil 4 and has a cylindrical sheath with grooves or openings 23 on its outer circumference. The openings 23 affect the magnetic flux flowing through the pole tube 3. The openings prevent magnetic short circuits. The reduced magnetic cross-section of the iron due to the openings 23 has already saturated under low coil currents and thus acts similarly to the air gap between the magnetic core and the pole shoe. The cylindrical sheath of the pole tube 3 may also have an inner groove 20. The cylindrical armature 5 is slidably supported in the inner groove 20 of the electrode 3. The embodiment with the electrode 3 is considered an exemplary implementation of the electromagnet 2. Of course, other electromagnets without electrodes can also be used.

[0025] Below the armature 5, the pole tube 3 has a through opening for the actuating element 7, which is kinetically coupled to the armature 5. The actuating element 7 may be constructed as a metal pin and movably supported in the groove 10 along the axial direction 100. The armature 5 may have a central inner bore into which the armature bolt 26 is pressed. The armature 5 moves back and forth in the inner groove of the pole tube 3 according to the magnetic force of the magnetic coil 4 and the reaction force acting on the armature 5 by the adjusting element 7 and, if necessary, by a spring (not shown).

[0026] exist Figure 1 At one end of the magnetic coil 4, the pole piece 27 is fitted onto the pole tube 3. Figure 1 At the other end of the magnetic coil, a flux guiding section 6 is arranged to close the magnetic circuit. For example, in... Figure 1 As can be seen, the flux guiding part 6 is constructed from two parts: a base part 12 facing the armature 5 and a head 11 facing away from the armature 5. The base part 12 and the head 11 can be made of sintered soft magnetic metal. The actuating element 7 loaded by the armature 5 is supported in a first bearing part 13 constructed at the head 11 and in a second bearing part 14 constructed at the base part 12 in a manner that allows it to move along the axial direction 100.

[0027] As in Figure 2As can be seen most clearly in the enlarged detailed view, the recess 10 accommodating the actuating element 7 is formed by a first drill hole 15 extending axially 100 in the head 11 and a second drill hole 16 connected to the first drill hole and extending axially 100 in the base portion. The head 11 is oriented at the base portion 12 such that the central axes of the two drill holes lie on a common straight line of the longitudinal axis 101 of the corresponding actuator 1.

[0028] If still Figure 2 As can be seen, the first bore 15 has a first inner diameter D1 in the axially extending region of the first bearing portion 13 of the operating element 7, which is configured to be smaller than the inner diameter D3 of the first bore 15 in the region outside the first bearing portion 13. The second bore 16 has a second inner diameter D2 in the axially extending region of the second bearing portion 14, which is configured to be smaller than the inner diameter D4 of the second bore 16 in the region outside the second bearing portion 14. The inner diameter D3 of the first bore 15 is preferably configured to be equal to the inner diameter D4 of the second bore 16. Furthermore, the first inner diameter D1 of the first bearing portion 13 can also preferably be configured to be equal to the second inner diameter D2 of the second bearing portion 14.

[0029] The first bearing portion 13 within the first borehole 15 is particularly preferably located at the end of the head 11 remote from the base portion 12, and the second bearing portion 14 within the second borehole 16 is located at the end of the base portion 12 remote from the head 11. The length L1 of the axially extending region of the first bearing portion 13 is clearly configured to be less than three times the first inner diameter D1. The length L2 of the axially extending region of the second bearing portion 14 may additionally or alternatively be configured to be less than three times the second inner diameter D2. The first inner diameter D1 and the second inner diameter D2 can be manufactured with high precision over short lengths L1 and L2. The actuating element 7 is guided radially only through the inner wall of the recess 10, whose diameter narrows, in the regions of the first bearing portion 13 and the second bearing portion 14.

[0030] In addition, Figure 1 It can also be seen that the head 11 of the flux guiding portion 6 has a protrusion 11b facing the base portion 12, which is fitted into the receiving portion 12a of the base portion 12. The head 11 may have a disc-shaped section 11a facing away from the base portion 12, and a cylindrical section with a smaller diameter than the disc-shaped section 11a, forming the protrusion 11b, protrudes from the disc-shaped section toward the base portion.

[0031] The protrusion 11b is fitted into the cylindrical inner wall of the receiving portion 12a of the base portion 12, so that the head 11 is oriented about the longitudinal axis 101 of the actuator 1 in its radial position relative to the base portion 12. The protrusion 11b can be pressed into the receiving portion 12a to secure the protrusion in the receiving portion 12a.

[0032] Figure 3a Head 11 is shown and Figure 3b The base portion 12 of the magnetic flux guiding portion 6 before the extrusion process is shown. Figure 3c The flux guiding section 6 is shown in its final, completed state. An annular groove 30 is formed between the disc-shaped section 11a of the head 11 and the end side 19 of the base portion 12. The bottom of this annular groove forms the outer wall of the protrusion 11b, and the annular groove serves as a fixing groove for securing the actuator 1 to the hydraulic system. (As shown in...) Figure 1 As can also be seen, the compression connection between the protrusion 11b and the receiving portion 12a has a large overlap length P, thus achieving a large connection force.

[0033] Figure 4b A second embodiment of the electromagnetic actuator is shown, which is constructed as closely as possible to... Figure 1 The embodiments are similar. However, unlike the first embodiment, at least one axially extending longitudinal channel 17 is constructed in the support region of the face sections of the protrusion 11b and the receiving portion 12a that face each other. (As in...) Figure 4a As shown, the longitudinal channel 17 can be constructed, for example, by machining a longitudinal groove extending axially 100 into the inner wall of the receiving portion 12. However, the longitudinal channel 17 can also be constructed as a longitudinal groove or a diameter-flattened structure at the outer sleeve of the protrusion 11b. Of course, more than one longitudinal channel 17 can be provided in this way.

[0034] As in Figure 4b As most clearly seen, the first end of the longitudinal channel 17 opens into the annular groove 30 at the end 19 of the base portion 12 facing the head 11. The second end of the longitudinal channel 17 connects to the groove 10 through the gap 18 between the base portion 12 and the head 11. A small amount of hydraulic fluid entering the groove 10 through the first bearing portion 13 can thus advantageously flow out into the annular groove 30 through the gap 18 and the longitudinal channel 17 before reaching the electromagnet 2. This prevents harmful substances contained in the hydraulic fluid from contaminating the electromagnet.

Claims

1. An electromagnetic actuator (1), comprising: An armature (5) movable in an armature chamber (20) along an axial direction (100); a magnetic coil (4) for generating a magnetic field to move the armature (5); an actuating element (7) coupled to the movement of the armature (5); and a flux guiding portion (6) arranged at the axial end of the magnetic coil (4), having a groove (10) extending along the axial direction (100), the actuating element (7) being movably arranged in the groove, wherein the flux guiding portion (6) is constructed of two parts, characterized in that the flux guiding portion (6) is constructed of a base portion (12) facing the armature (5) and a head (11) facing away from the armature (5), and the actuating element (7) is supported in a first bearing portion (13) constructed at the head (11) and in a second bearing portion (11) constructed at the base portion (12) in a manner movable along the axial direction (100). In the second bearing portion (14), the groove (10) is formed by a first bore (15) extending along the axial direction (100) in the head (11) and a second bore (16) connected to the first bore and extending along the axial direction (100) in the base portion, wherein the first bore (15) has a first inner diameter (D1) in the axially extending region of the first bearing portion (13), the first inner diameter being configured to be smaller than the inner diameter (D3) of the first bore (15) in the region outside the first bearing portion (13), and / or the second bore (16) has a second inner diameter (D2) in the axially extending region of the second bearing portion (14), the second inner diameter being configured to be smaller than the inner diameter (D4) of the second bore (16) in the region outside the second bearing portion (14).

2. The electromagnetic actuator according to claim 1, characterized in that, The first bearing portion (13) in the first borehole (15) is located at the end of the head (11) away from the base portion (12), and the second bearing portion (14) in the second borehole (16) is located at the end of the base portion (12) away from the head (11).

3. The actuator according to claim 1 or 2, characterized in that, The length (L1) of the axial extension region of the first bearing portion (13) is less than three times the first inner diameter (D1), and / or the length (L2) of the axial extension region of the second bearing portion (14) is less than three times the second inner diameter (D2).

4. The actuator according to claim 1 or 2, characterized in that, The head (11) has a protrusion (11b) facing the base portion (12), the protrusion being fitted into and fixed in the receiving portion (12a) of the base portion (12).

5. The actuator according to claim 4, characterized in that, The head (11) has a disc-shaped section (11a) facing away from the base portion (12), and a cylindrical section forming the protrusion (11b) with a smaller diameter than the disc-shaped section (11a) protrudes from the disc-shaped section toward the base portion.

6. The actuator according to claim 4, characterized in that, The protrusion (11b) is fitted into the cylindrical inner wall of the receiving portion (12a) of the base portion (12), thereby oriented the head (11) relative to the base portion (12) in its radial position about the longitudinal axis (101) of the actuator (1).

7. The actuator according to claim 4, characterized in that, At least one longitudinal channel (17) extending axially is constructed in the support region of the face sections of the protrusion (11b) and the receiving portion (12a) facing each other.

8. The actuator according to claim 7, characterized in that, The first end of the longitudinal channel (17) extends into the annular groove (30) at the end side (19) of the base portion (12) facing the head (11), and the second end of the longitudinal channel (17) is connected to the groove (10) through the gap (18) between the base portion (12) and the head (11).

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