Solenoid valve, especially for slip-controlled motor vehicle braking systems

Abstract

An electromagnetic valve, particularly for hydraulic, slip-controlled motor vehicle braking systems, comprising a valve closing element (5) arranged in a valve housing (13), which, depending on the electromagnetic excitation of a valve coil in the valve housing (13), is able to open a valve passage provided in a valve seat (11), comprising a pressure medium inlet (15) opening into a valve chamber (1) of the valve housing (13) and a pressure medium outlet (16), both of which can be connected to each other via the valve passage in the valve seat (11), comprising a compression spring (8) which is supported on a magnetic core (12) fixed in the valve housing (13) for the purpose of positioning the valve closing element (5), which interacts with a magnetic armature (3) supporting the plunger-shaped valve closing element (5), and comprising an intermediate space (2) bounded by the magnetic armature (3) and the magnetic core (12), which is hydraulically actuated, characterized in thatthat the valve closing element (5) with its plunger section (4) projecting both towards the valve seat (11) and towards the magnetic core (12) on the magnetic armature (3) is movably received in a longitudinal bore (7) vertically penetrating the magnetic armature (3), in which a piston (6) is arranged between two chambers (9, 10) such that pressure medium from the two chambers (9, 10) can be displaced by means of the piston (6) to dampen the impact of the plunger section (4) connected to the piston (6).

Description

[0001] The invention relates to an electromagnetic valve, in particular for slip-controlled motor vehicle brake systems, according to the preamble of patent claim 1.

[0002] An electromagnetic valve of the specified type is already known from DE 10 2012 214 510 A1, in whose valve housing a valve closing body is arranged, which, depending on the electromagnetic excitation of a valve coil, can open a valve passage provided in a valve seat in the valve housing. A pressure medium inlet and a pressure medium outlet open into a valve chamber of the valve housing, both of which are connectable to one another via a passage in the valve seat. For the basic positioning of the valve closing body in the valve housing, a compression spring is supported on a magnetic core fixed in the valve housing, which urges a magnetic armature carrying the valve closing body towards the valve seat. The presented electromagnetic valve has the disadvantage that undesirable noises are generated during switching.

[0003] Furthermore, DE 69 04 282 U discloses an electromagnetic valve comprising a valve housing closed by a magnetic core, wherein a guide tube is fitted into the valve housing, within which is an armature comprising a spring chamber for receiving a return spring which is supported on the magnetic core via a guide pin. A plate-shaped closure piece is used as the valve closing body, which is mounted with radial and axial play in an annular recess 24 of the armature. This ensures that the closure piece is always held sealingly on the valve seat piece. The valve seat piece sits in a bore which is connected to the inlet channel. An annular space surrounding the valve seat piece is connected to the outlet channel.When the solenoid coil is energized, the armature is lifted and the valve plate lifts off the valve seat piece, creating a fluid connection between the inlet channel and the outlet channel, whereby the valve plate is surrounded by fluid on both sides.

[0004] It is the object of the present invention to improve a solenoid valve of the type specified using the simplest, most functional means possible, in a cost-effective and compact manner, so that the aforementioned valve switching noises do not occur.

[0005] This object is achieved according to the invention with an electromagnetic valve according to the features of patent claim 1.

[0006] Further features and advantages of the invention will become apparent from the following description of several embodiments.

[0007] They show: Fig. 1-5 a solenoid valve in longitudinal section in different switching positions to illustrate the mode of operation of the proposed invention, Fig. 6 a variant of the Fig. 1-5 of the magnet armature shown in longitudinal section, whose integrated piston is provided with a noise-reducing coating, Fig. 7 a further variant for the design of the piston integrated in the magnet armature, which is provided with an additional seal on the circumference, Fig. 8 in addition to the piston seal in the magnet armature, a seal of the plunger section connected to the piston in the longitudinal bore of the magnet armature, Fig. 9 which from the Fig. The arrangement shown in Figure 8 is supplemented by a filling valve for supplying the chambers bordering the piston in the magnet armature on both sides, which are connected to each other via a through hole in the piston.

[0008] The Fig. The electromagnetic valve shown in Figures 1 to 5, considerably enlarged in longitudinal section, is preferably suitable for use in a hydraulic, slip-controlled motor vehicle braking system. It has at least one valve closing body 5 arranged in a cartridge-shaped valve housing 13, which, depending on the electromagnetic excitation of a valve coil 18, is capable of opening a valve passage provided in a valve seat 11 in the valve housing 13. In the present exemplary embodiment, the valve seat 11 is a component of a valve piston 14 guided in the valve housing 13, which, in terms of its function, represents the main stage of a two-stage seat valve that is pilot-controlled via the valve closing body 5 and closed in the basic position.

[0009] Furthermore, at the level of the valve closing body 5, a so-called valve chamber 1 is provided between a pressure medium inlet 15 opening into the valve housing 13 and a pressure medium outlet 16, both of which can be connected to one another exclusively via the passage in the valve seat 11 (which in the present embodiment is not fixedly arranged in the valve housing 13, but in the axially movable valve piston 14), as long as the valve piston 14 rests on its valve seat body 17, which is fixed below the valve piston 14 in the valve housing 13.

[0010] For the basic positioning of the valve closing body 5 on the valve seat 11 of the valve piston 14, a compression spring 8 acting on a magnet armature 3 is supported on a magnet core 12 closing the valve housing 13. For electromagnetic actuation of the valve closing body 5 into its open position, the magnet armature 3 supporting the valve closing body 5 is moved toward the magnet core 12.

[0011] Furthermore, a so-called intermediate space 2 is provided in the valve housing 13, which is delimited by the magnet armature 3 and the magnet core 12, wherein the intermediate space 2 can be permanently connected to the valve chamber 1 for venting and unhindered hydraulic filling, if required, either via the longitudinal bore 7 penetrating the magnet armature 3 or along the armature surface. In order to avoid undesirable impact noise in both stroke directions of the magnet armature, the invention provides that the valve closing body 5, with its tappet section 4 projecting both in the direction of the valve seat 11 and in the direction of the magnetic core 12 on the magnet armature 3, is movably received in a longitudinal bore 7 penetrating vertically through the magnet armature 3, in which a piston 6 is arranged between two chambers 9, 10 in such a way that, in order to dampen impact during the movement of the magnet armature 3, pressure medium must be displaced from one of the two chambers 9, 10 by the piston 6 connected to the tappet section 4. The avoidance of undesirable valve impact noise is thus based on hydraulic damping of the armature movement as a result of the piston 6 arranged on the tappet section 4.

[0012] To maintain a desired damping characteristic, according to the Fig. 1 to 8, each of the two chambers 9, 10 is hydraulically connected either to the valve chamber 1 or to the intermediate chamber 2 via a throttle opening 20 arranged within the magnet armature 3. According to the Fig. 1 to 8, the throttle opening 20 is therefore produced in a particularly simple manner by a radial play dimensioned accordingly for the movable reception of the tappet section 4 in the longitudinal bore 7 of the magnet armature 3, so that the chamber 9 arranged above the piston 6 is connected to the intermediate space 2 via the annular throttle opening 20 located thereabove, while the chamber 10 arranged below the piston 6 is hydraulically connected to the valve chamber 1 via the associated annular throttle opening 20.

[0013] As can be seen from all Fig. 1 to 9, one of the two throttle openings 20 leads through a bushing 21 fixed below the chamber 10 in the longitudinal bore 7 of the magnet armature 3, through which the tappet section 4 extends with its closing head in the direction of the valve seat 11 into the valve chamber 1.

[0014] Based on the Fig. 1 to 5 will now briefly highlight the special features / effects of the subject matter of the invention.

[0015] The Fig. 1 the electromagnetic valve in its electromagnetically non-excited, closed basic position, in which the valve closing body 5 closes the passage in the valve seat 11, for which purpose, under the action of the compression spring 8, the magnet armature 3 in the chamber area directly contacts the piston 6 arranged in the emptied chamber 9 in the manner of a driver.

[0016] The Fig. Figure 2 shows the solenoid valve at the beginning of its electromagnetic actuation, in which the solenoid armature 3 is lifted toward the magnetic core 12 against the spring force of the compression spring 8. The stroke of the solenoid armature 3 displaces the fluid located below the piston 6 in the chamber 10 through the throttle opening 20 into the valve chamber 1. The cross-section of the annular throttle opening 20 is designed so that the fluid can only flow out slowly, creating a pressure cushion in the chamber 10 between the bushing 21 and the piston 6. This pressure cushion causes the piston 6, and thus the entire valve closing body 5, to follow the movement of the solenoid armature 3 with hydraulic damping. Since the valve closing body 5, with its tappet section 4, protrudes beyond the upper edge of the solenoid armature 3, the upper end of the tappet-shaped valve closing body 5 first comes into contact with the underside of the magnetic core 12.The protruding plunger of the valve closing body 5 now rests on the magnetic core 12, while the armature 3 continues to move toward the magnetic core 12. Thus, the pressure cushion in the chamber 10 acts as a damper for the armature 3 and slows it down toward the magnetic core 12, preventing the armature impact noise.

[0017] At the same time, due to the two-stage valve design, the piston spring 19 pushes the valve piston 14 towards the magnetic core 12 and the large valve cross-section on the valve seat body 17 is opened.

[0018] When the solenoid valve is fully open, Fig. 3, both the upper tappet end of the valve closing body 5 and the magnet armature 3 touch the magnet core 12; and the piston 6 is no longer in contact with the magnet armature 3, while the chamber 9 arranged above the piston 6 in the magnet armature 3 is filled by the fluid volume displaced from the intermediate space 2. The piston spring 19 presses the valve piston 14 unchanged against the tappet 4, whereby the latter remains in a defined position and the large valve cross-section on the valve seat body 17 remains open.

[0019] The Fig. Figure 4 shows the solenoid valve after the electromagnetic excitation has ceased, so that the compression spring 8 moves the solenoid armature 3 downward in the valve closing direction. Due to the movement of the solenoid armature 3, the fluid in the chamber 9 is displaced by the action of the piston 6 through the throttle opening 20 into the expanding space 2. The cross-section of the annular throttle opening 20 is designed such that the fluid can only flow out slowly and a pressure cushion builds up in the chamber 9. The pressure cushion causes the piston 6 with the valve closing body 5 to follow the downward stroke of the solenoid armature 3 with hydraulic damping.

[0020] The valve closing body 5 thus pushes the valve piston 14 in the closing direction against the spring force of the piston spring 19 until the valve piston 14 hits the valve seat body 17 and closes the large valve passage, while the magnet armature 3 continues to move downward. As a result, the pressure cushion above the piston 6 in the chamber 9 acts as a damper for the magnet armature 3 and slows it down.

[0021] As soon as the chamber 9 is completely emptied, the magnet armature 3 hits the piston 6 in the area of ​​the longitudinal bore 7 at only a low speed, so that finally according to the Fig. 5 a direct coupling is created between the magnet armature 3 and the valve closing body 5, which presses the valve piston 14 against the valve seat body 17 due to the action of the compression spring 8.

[0022] This ensures that the hard impact of the valve piston 14 on the valve seat body 17 and the impact of the magnet armature 3 on the piston 6 do not occur simultaneously, whereby the previous single impact noise is divided into two individual impact pulses that are no longer acoustically perceptible.

[0023] Furthermore, the Fig. 6 a practical design of the piston 6, which is provided on both sides with an elastic coating 23 or, if desired or required, with an elastic disc to optimize the noise behavior.

[0024] For a better design of the pressure cushions in the chambers 9, 10, it may be necessary to introduce one or more channels in the magnet armature 3 and / or in the bushing 21 in addition to the annular throttle openings 20 (see Fig. 7) . In addition, a seal 24 is arranged on the circumference of the piston 6 in order to reliably prevent an undesired hydraulic connection between the two chambers 9, 10 via the piston skirt.

[0025] Another practical embodiment provides for radial sealing of the tappet section 4 in the longitudinal bore 7 and in the bushing 21 with seals 26. For the fluid to flow out, one or more channels are then required in the magnet armature 3 and / or in the bushing 21 (see Fig. 8, Fig. 9)

[0026] In addition to the throttle openings 20 formed by the radial play on the valve closing body, Fig. 7 and Fig. 8 in parallel arrangement to the two throttle openings 20, additional calibrated through holes 22 are provided in the bushing 21 and in the magnet armature 3, which hydraulically connect the valve chamber 1 with the chamber 10 adjacent to the bushing 21 and the intermediate chamber 2 with the chamber 9.

[0027] In addition, it may be useful to Fig. 9 the two chambers 9, 10 are to be designed as a self-contained working chamber which is connected to one another by one or more channels in the piston 6. To do this, the tappet section 4 in the longitudinal bore 7 must be radially sealed with seals 26 and the piston 6 must also be radially sealed with a seal 24. One or more overflow openings must then be introduced into the piston 6, which, when the electromagnet is actuated, allow the fluid to flow from one chamber to the next and back again. The cross-section of the overflow opening must be designed such that the fluid can only flow over slowly and thus a pressure cushion always builds up in one of the two chambers 9, 10.

[0028] To fill the chambers 9, 10, it is advantageous to arrange a check valve 25 in the bushing 21 or in the magnet armature 3. Alternatively, the bore required to fill the chambers 9, 10 can be tightly closed after the filling process (e.g., by pressing in a ball).

[0029] Thus, the Fig. 9 deviating from the Fig.1-8 a closed chamber system, since the two chambers 9, 10 are sealed off from the valve chamber 1 and the intermediate space 2 along the tappet section 4, which is why the piston 6 has a throttle opening 20 for displacing pressure medium from one of the two chambers 9, 10 into the other chamber 9, 10, which throttle opening connects both chambers 9, 10 with each other. For hydraulically filling the chambers 9, 10 with the pressure medium located in the valve chamber 1, a check valve 25 is provided which opens in the direction of the chambers 9, 10 and which, as shown, is arranged either in the through-bore 22 of the bushing 21 or in the magnet armature 3.

[0030] Finally, it should not go unmentioned that the valve closing body 5 and the piston 6 can be designed either as a one-piece component or as an assembly consisting of two or more components.

[0031] In the case of a multi-part assembly, it may be useful to mount the piston 6 in such a way that it can be moved during the assembly process (e.g. using a pressing device) in order to adjust the stroke of the valve.

[0032] Further noise reduction can be achieved if the piston 6 is made of a non-metallic material (e.g., plastic or elastomer). A piston 6 made of an elastomer material has the additional advantage that it can deform elastically at high pressures in the chambers 9, 10, opening up a larger cross-section for overflow. This prevents the increase in fluid viscosity from leading to excessively high pressure in the chambers 9, 10 at temperatures below freezing. This would increase the damping and lengthen the valve's switching times. The same applies to the valve closing body 5, which can also be made of a non-metallic material or coated with an elastic material at the ends. It is also possible to arrange additional components made of non-metallic materials (e.g., plastic or elastomer) at the ends of the tappet-shaped valve closing body 5.

[0033] In order to reduce the noise as effectively as possible, the contour (e.g. spherical, conical, cylindrical) on the contact surface of the valve closing body 5 to the magnetic core 12 must be adapted accordingly.

[0034] As already mentioned at the beginning, the electromagnetic valve shown is a two-stage valve, consisting of a pilot stage and a main stage, which, as shown, is formed by the valve piston 14 resting on the large valve seat body 17, which receives the valve seat 11 for the pilot stage formed by the valve closing body 5, so that only after the electromagnetic actuation of the pilot stage does the valve piston 14 release the valve seat body 17 under the action of a piston spring 19, which is placed between the valve piston 14 and the valve housing 13.

[0035] Separate from this two-stage design, the invention can also be applied to a single-stage seat valve which is closed in the electromagnetically non-energized basic position and which does not have the described features for the main stage (valve seat 11 and valve seat body 17 integrated in the valve piston 14), so that the valve closing body 5 shown then comes to rest on a valve seat 11 fixed directly in the valve housing 13, without thereby departing from the solution of the proposed invention. List of reference symbols 1 valve chamber 2 space 3 magnet armatures 4 Tappet section 5 valve closing body 6 pistons 7 Longitudinal bore 8 compression spring 9 Chamber 10 chambers 11 Valve seat 12 magnetic core 13 Valve housing 14 valve pistons 15 Pressure medium inlet 16 Pressure medium outlet 17 Valve seat body 18 Valve coil 19 Piston spring 20 Throttle opening 21 socket 22 through hole 23 Coating 24 Seal 25 Check valve 26 Seal

Claims

[1] Electromagnetic valve, in particular for hydraulic, slip-controlled motor vehicle brake systems, with a valve closing body (5) arranged in a valve housing (13), which can open a valve passage provided in a valve seat (11) depending on the electromagnetic excitation of a valve coil in the valve housing (13), with a pressure medium inlet (15) opening into a valve chamber (1) of the valve housing (13) and a pressure medium outlet (16), both of which can be connected to one another via the valve passage in the valve seat (11), with a compression spring (8) which, for the basic positioning of the valve closing body (5), is supported on a magnetic core (12) fixed in the valve housing (13), which interacts with a magnetic armature (3) carrying the tappet-shaped valve closing body (5), and with an intermediate space (2) delimited by the magnetic armature (3) and the magnetic core (12), which is hydraulically acted upon, characterized bythat the valve closing body (5) with its tappet section (4) projecting both in the direction of the valve seat (11) and in the direction of the magnetic core (12) on the magnet armature (3) is movably received in a longitudinal bore (7) penetrating vertically through the magnet armature (3), in which a piston (6) is arranged between two chambers (9, 10) in such a way that pressure medium can be displaced from the two chambers (9, 10) with the aid of the piston (6) in order to dampen the impact of the tappet section (4) connected to the piston (6). [2] Solenoid valve according to claim 1, characterized by that each of the two chambers (9, 10) is hydraulically connected either to the valve chamber (1) or to the intermediate chamber (2) via a throttle opening (20) arranged within the magnet armature (3). [3] Solenoid valve according to claim 2, characterized bythat the throttle opening (20) is formed by a radial play provided for the movable reception of the tappet section (4) in the longitudinal bore (7) of the magnet armature (3) [4] Solenoid valve according to claim 3, characterized by that a bushing (21) fixed in the longitudinal bore (7) has the throttle opening (20) hydraulically connected to the valve chamber (1), through which the tappet section (4) extends in the direction of the valve seat (11). [5] Solenoid valve according to claim 4, characterized by that the bushing (21) has a calibrated through-bore (22) arranged parallel to the throttle opening (20), which hydraulically connects the valve chamber (1) to the chamber (10) adjacent to the bushing (21). [6] Solenoid valve according to claim 1, characterized by that the piston (6) is provided on both sides with an elastic coating (23) or an elastic disc. [7] Solenoid valve according to claim 1, characterized bythat the piston (6) has a seal (24) on its piston skirt for sealing in the longitudinal bore (7). [8] Solenoid valve according to claim 1, characterized by that the two chambers (9, 10) are hydraulically separated from the valve chamber (1) and the intermediate space (2) along the tappet section (4), and that the piston (6) has a throttle opening (20) which connects both chambers (9, 10) to one another in order to displace pressure medium from one of the two chambers (9) into the other chamber (10). [9] Solenoid valve according to claim 8, characterized by that for the hydraulic filling of the chambers (9, 10) with the pressure medium located in the valve chamber (1), a check valve (25) opening in the direction of the chambers (9, 10) is provided, which is arranged either in the through-bore (22) of the bushing (21) or in the magnet armature (3).

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