Two-stage solenoid valve

Abstract

To reduce the whole stroke of a magnetic armature without restricting functions of a solenoid valve.SOLUTION: A valve cartridge 10 comprises a pole core 14, a magnetic armature 16 which can move axially between a closing position and an opening position against force of a return spring 17 with magnetic force generated by a magnet assembly 3 inside a valve sleeve 12, a front stage 20 which has a first valve seat 24 and a first closing element 26, and a main stage 30 which has a larger second valve seat 34 and a second closing element 36. The magnetic armature 16 is connected to the first closing element 26, and also coupled to the second closing element 36 through a spring element 28 to enable relative motion, restricted with an adjustable front-stage stroke hV, between the first closing element 26 and second closing element 36 against elastic force of the spring element 28, and an adjustable operation gap 18 between the magnetic armature 16 and pole core 14 sets the whole stroke hG of the magnetic armature 16 in advance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The starting point is the two-stage solenoid valve. [Background technology]

[0002] In hydraulic braking systems of vehicles with ESP functionality (ESP: Electronic Stability Program), ASR functionality (ASR: Traction Control System) and / or ABS functionality (ABS: Anti-lock Brake System), valves configured as solenoid valves for adjusting the fluid flow for the different functions are used for driving dynamics control. The solenoid valves are used as technical components for controlling the intake or discharge of fluid or for open-loop and / or closed-loop control of the flow direction and / or the fluid quantity. From the field of hydraulic braking systems of such vehicles, various systems are known in which an active or partially active pressure boost in a hydraulic or hydraulic unit is realized via a high-pressure changeover valve with a front stage and a main stage and configured as a currentless closed-valve two-stage solenoid valve. Two-stage solenoid valves are used in particular when a high volume flow or high pressure must be switched over at a low pressure. When actuated or operated, the two-stage solenoid valve opens the flow path, for example, between the master brake cylinder or the primary circuit and the pump element or the secondary circuit. The two-stage configuration allows the solenoid valve to open or the flow path to be opened even when the pressure difference is large. In this case, the primary circuit is connected to the first fluid opening of the two-stage solenoid valve, and the secondary circuit is connected to the second fluid opening, with the first closing element of the front stage and the second closing element of the main stage being arranged between these fluid openings.

[0003] From the patent DE 10 200 03 13 599 A1 a corresponding two-stage solenoid valve is known, which comprises a magnet assembly surrounding a coil winding arranged in a casing jacket and a valve cartridge, which comprises a pole core, a magnetic armature axially movable between a closed position and an open position in a valve sleeve, at least one first fluid opening, at least one second fluid opening, a front stage with a first valve seat and a first closing element, and a main stage with a larger second valve seat and a second closing element. The magnetic armature is connected to the first closing element and is coupled to the second closing element via a spring element. Between the first and second closing elements, a relative movement limited by an adjustable front stage stroke is possible against the repulsive force of the spring element, and an adjustable operating gap between the magnetic armature and the pole core predefines the full stroke of the magnetic armature. The valve cartridge has an end on the pole core side at least partially inserted into the magnet assembly, an upper end of the magnet assembly abutting against the pole core, and a lower end of the magnet assembly abutting against the valve sleeve. The magnet assembly generates a magnetic field by energizing the coil winding, and the magnetic field moves the magnetic armature against the force of the return spring. Typically, when the solenoid valve opens, the magnetic armature first lifts the first closing element from the first valve seat by a first stage stroke toward the pole core when the fluid force caused by the current pressure difference between the at least one first fluid opening and the at least one second fluid opening is greater than the repulsive force of the spring element, thereby opening the front stage with a smaller seat diameter. Then, the magnetic armature lifts the second closing element from the second valve seat to a stopper by the remaining stroke, and at the same time, the first closing element continues to move to the stopper by the remaining stroke toward the pole core, thereby opening the main stage. After pressure compensation between the at least one first fluid opening and the at least one second fluid opening, the resilience of the spring element moves the second closing element having the first valve seat by a front stage stroke in the direction of the pole core to the first valve seat, or the front stage is closed and the second valve seat or main stage is fully open.That is, the total stroke of the magnetic armature is composed of the front stage stroke and the remaining stroke, and is therefore large. When the fluid force caused by the current pressure difference between the at least one first fluid opening and the at least one second fluid opening is smaller than the repulsive force of the spring element, the front stage remains closed, and the magnetic armature moves the first closing element and the second closing element simultaneously by the full stroke toward the pole core to the stopper, thereby directly opening the main stage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 102008001864 A1 Summary of the Invention

[0005] A two-stage solenoid valve having the features of independent claim 1 has the advantage that the total stroke of the magnetic armature can be reduced without the function of the solenoid valve being restricted. The reduced total stroke advantageously allows the operating air gap to be adjusted to be smaller, which in turn reduces the magnetic current required to open the solenoid valve. Furthermore, the construction height of the two-stage solenoid valve can be reduced. [Means for solving the problem]

[0006] An embodiment of the present invention provides a second solenoid valve having a magnet assembly and a valve cartridge, the valve cartridge comprising a pole core, a magnetic armature axially movable between a closed position and an open position against the force of a return spring by a magnetic force generated by the magnet assembly in a valve sleeve, at least one first fluid opening, at least one second fluid opening, a front stage having a first valve seat and a first closing element, and a main stage having a larger second valve seat and a second closing element. The magnetic armature is connected with the first closing element and is coupled with the second closing element via a spring element. A relative movement limited by an adjustable front stage stroke between the first closing element and the second closing element is possible against the repulsive force of the spring element, and an adjustable working gap between the magnetic armature and the pole core presets a full stroke of the magnetic armature. In this case, the magnetic armature opens the front stage or the main stage, respectively, with the same full stroke during its opening movement, and the front stage stroke is adjusted to be larger than the full stroke of the magnetic armature.

[0007] The essence of the invention is that the front stage or the main stage, respectively, is opened with the same total stroke. This advantageously results in a smaller total stroke of the magnetic armature in the de-energized state of the solenoid valve, as well as a smaller operating gap between the pole core and the magnetic armature. In this case, in order to be able to close both stages of the solenoid valve, the possible front stage stroke is adjusted to be minimally larger than the total stroke. In particular, the operating gap can be adjusted so that in the energized state, the magnetic armature directly abuts on the pole core. This results in a smaller holding current in the energized state. In addition to this, a smaller operating gap with the same form of magnet assembly makes it possible to use a larger magnetic force to move the magnetic armature, which allows shorter switching times and a larger switchable pressure difference to be achieved with less energy required. In addition, the shorter acceleration distances result in less noise when the solenoid valve is switched. Due to the properties of the spring element, the threshold pressure difference for opening the main stage can be set smaller, so that during pressure compensation when the secondary stage is open, the pressure compensation shock when opening the main stage is smaller.

[0008] In the embodiment of the two-stage solenoid valve according to the invention, only a rough adjustment of the prestroke is necessary, whereby a fixed pre-inpression mass is sufficient to adjust the prestroke at least slightly more than the full stroke, thereby eliminating the need for a laborious adjustment process on the production line. When the two-stage solenoid valve according to the invention is used between the master brake cylinder and the pump element in a hydraulic brake system, there is no different flow cross section depending on the flow rate when closing the second closing element, which results in a better pedal feel.

[0009] Advantageous refinements of the two-stage solenoid valve according to the independent claim 1 are possible by means of the measures and developments set out in the dependent claims.

[0010] It is particularly advantageous that the magnetic armature can open the first valve seat via the first closing element or open the second valve seat via the second closing element depending on the current pressure difference between the at least one first fluid opening and the at least one second fluid opening. Thus, if the current pressure difference between the at least one first fluid opening and the at least one second fluid opening is greater than a threshold value, the magnetic armature can move the first closing element from the first valve seat. In this case, after pressure compensation between the at least one first fluid opening and the at least one second fluid opening, the spring element can move the second closing element from the second valve seat to open the main stage and close the front stage. Furthermore, if the current pressure difference between the at least one first fluid opening and the at least one second fluid opening is equal to or less than a threshold value, the magnetic armature can move the second closing element from the second valve seat to open the main stage while keeping the front stage closed. The threshold value can be preset and adjusted in particular in relation to the properties of the spring element used.

[0011] In an advantageous embodiment of the solenoid valve, the spring force of the spring element may be preset to be greater in the closing direction than the corresponding fluid force when flowing through the second valve seat and to be able to hold the main stage open.

[0012] In a further advantageous embodiment of the solenoid valve, the first valve seat can be arranged, for example, in the first axial through-opening of the second closing element. The second closing body can be arranged at least partially in the pre-capsule, the first valve seat being arranged in the pre-capsule. In this case, the pre-capsule can be rigidly connected with its open end to the connection area of ​​the magnetic armature. The second closing element can thus, for example, with its end facing away from the magnetic armature, pass through the axial opening of the pre-capsule and be supported on the edge of the opening in the pre-capsule via a spring element. In addition to this, a stop can be formed on the second closing element. In this case, the distance between the stop of the second closing element and the edge of the opening in the pre-capsule can determine the pre-stroke. This allows for a simple adjustment of the pre-stroke by presetting a pre-adjusted pushing-in stroke, at which the pre-capsule is pressed against the connection area of ​​the magnetic armature or the magnetic armature is pushed into the pre-capsule. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a schematic cross-sectional view of an embodiment of a two-stage solenoid valve according to the present invention in a closed state with no current. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the two-stage solenoid valve according to the present invention of FIG. 1 when the front stage is open. [Diagram 3] FIG. 3 is a schematic cross-sectional view of the two-stage solenoid valve according to the present invention of FIGS. 1 and 2 when the main stage is open and the front stage is closed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Exemplary embodiments of the invention are illustrated in the drawings and explained in detail in the following description, in which like reference numbers indicate parts or elements that perform the same or similar functions.

[0015] As can be seen from Figures 1 to 3, the illustrated embodiment of a solenoid valve 1 according to the invention comprises a magnet assembly 3 and a valve cartridge 10. The valve cartridge 10 comprises a pole core 14, a magnetic armature 16 axially movable between a closed position and an open position against the force of a return spring 17 by a magnetic force generated by the magnet assembly 3 in the valve sleeve 12, at least one first fluid opening 19.1, at least one second fluid opening 19.2, a front stage 20 having a first valve seat 24 and a first closing element 26, and a main stage 30 having a larger second valve seat 34 and a second closing element 36. The magnetic armature 16 is connected to the first closing element 26 and is coupled to the second closing element 36 via a spring element 28. A relative movement limited by an adjustable pre-stage stroke hV between the first closing element 26 and the second closing element 36 is possible against the resilience of the spring element 28, and an adjustable working gap 18 between the magnetic armature 16 and the pole core 14 pre-sets a total stroke hB of the magnetic armature 16. In this case, the magnetic armature 16 opens the pre-stage 20 or the main stage 30, respectively, during its opening movement with the same total stroke hG, the pre-stage stroke hV being adjusted to be greater than the total stroke hG of the magnetic armature 16.

[0016] As can be further seen from Fig. 2, this means that the magnetic armature 16 opens the first valve seat 24 via the first closing element 26 or opens the second valve seat 34 via the second closing element 36 depending on the current pressure difference P1-P2 between the at least one first fluid opening 19.1 and the at least one second fluid opening 19.2. In this case, the magnetic armature 16 moves the first closing element 26 from the first valve seat 24 if the current pressure difference P1-P2 between the at least one first fluid opening 19.1 and the at least one second fluid opening 19.2 is greater than a threshold value. As can be further seen from Fig. 3, after pressure compensation between the at least one first fluid opening 19.1 and the at least one second fluid opening 19.2, the spring element 28 moves the second closing element 36 from the second valve seat 34 to open the main stage 30 and close the front stage 20. As can be seen from Fig. 3, the magnetic armature 16 moves the second closing element 36 away from the second valve seat 34 to open the main stage 30 while keeping the front stage 20 closed if the current pressure difference P1-P2 between the at least one first fluid opening 19.1 and the at least one second fluid opening 19.2 is below a threshold value. In this case, the first closing element 26 is moved together with the magnetic armature 16 due to its connection with it, but without lifting it off the first valve seat 24. In the illustrated embodiment, the threshold value may be preset and adjusted in relation to the characteristics of the spring element 28 used. In this case, the spring force of the spring element 28 is preset such that, when flowing through the second valve seat 34, it is greater in the closing direction, i.e. from the at least one first fluid opening 19.1 to the at least one second fluid opening 19.2, and is able to hold the main stage 30 open.

[0017] As can be further seen from FIGS. 1 to 3, in the illustrated exemplary embodiment, the two-stage solenoid valve 1 is configured as a currentless closed two-stage switching valve, which can be used, for example, as a high-pressure switching valve in a hydraulic brake system of a vehicle. In an ESP system (ESP: Electronic Stability Program), two special valves are used in comparison with an ABS system (ABS: Antilock Brake System). One of the two valves is such a high-pressure switching valve. In the first case, this high-pressure switching valve allows intervention in the brake system without a driver request. For this, the suction passage for the pump must be opened, so that the pump can provide the pressure required for control on behalf of the driver. In the second case, a conflict can occur between the driver's request (brakes) and the ESP control for stabilizing the vehicle. For this, this passage must then be able to be opened against the pressure (high pressure) provided by the driver.

[0018] In the above two cases, the illustrated currentless closed-valve type two-stage solenoid valve 1 may be used, and the valve seats 24, 34 of the solenoid valve can be opened via the movable magnetic armature 16 by energizing the coil winding 3.3 of the magnet assembly 3 depending on the application (no pressure, large seal seat) or the operator's request (high pressure, small seal seat, and large seal seat again with a drop in high pressure).

[0019] 1 to 3, in the illustrated embodiment, a return spring 17 is arranged between the pole core 14 and the magnetic armature 16. In this case, the magnetic armature 16 has a spring receiving portion formed as a central blind hole, which at least partially receives and guides the return spring 17.

[0020] As can be further seen from FIGS. 1-3, in the illustrated embodiment of the two-stage solenoid valve 1 according to the invention, the valve cartridge 10 comprises a valve lower part 19 connected with the valve sleeve 12, which is formed as a sleeve into which the annular valve body 32 is pressed. In the illustrated embodiment of the two-stage solenoid valve 1, the second closing element 34 is formed as a sealing bush 36A, and the first valve seat 24 is arranged in a first axial through-opening 38 of the second closing element 36. In addition to this, the second closing element 36 is at least partially arranged in the pre-stage capsule 22, and the first valve seat 34 is arranged in the pre-stage capsule 22. The pre-stage capsule 22 is rigidly connected with its open end to the connection area 16.1 of the magnetic armature 16. The flow path from the at least one first fluid opening 19.1 to the pre-stage 20 passes through at least one inlet opening 39 in the pre-stage capsule 22. In addition to this, an axial gap 42 is formed between the magnetic armature 16 and the pre-stage capsule 22. In the embodiment shown, a number of inlet openings 39 are made as radial holes into the precapsule 22 and lead into the surrounding axial gap 42 .

[0021] As can be seen further from FIGS. 1 to 3, the second closing element 36 is arranged axially movably in the pre-stage capsule 22. A spring element 28 is arranged here between the pre-stage capsule 22 and the second closing element 36, which in the illustrated embodiment is formed as a compression coil spring, which presses the second closing element 36 in the direction of the magnetic armature 16, so that the first closing element 26 can seal the first valve seat 24 arranged in the first axial through-opening 38 in the current-free state of the solenoid valve 1 shown in FIG. 1. As can be seen further from FIGS. 1 to 3, in the illustrated embodiment, the first closing element 26 is formed as a closing ball 26A and is firmly connected to the magnetic armature 16. The second closing element 36, with its end facing away from the magnetic armature 16, passes through the axial end opening 23 of the pre-stage capsule 22 and is supported by the spring element 28 on the edge 23.1 of the opening 23 in the pre-stage capsule 22. The second closure element 36A is provided with a stop 36.2, which in the illustrated embodiment is formed as a stop shoulder 36.2A. In this case, the distance between the stop 36.2 of the second closure element 36 and the edge 23.1 of the opening 23 in the pre-stage capsule 22 determines the pre-stage stroke hV.

[0022] As can be seen further from FIGS. 1 to 3, the valve lower part 19 is formed as a sleeve, into which the ring-shaped valve body 32 is pressed. The valve body 32 has a second axial through-opening 33 with a larger cross-section than the first through-opening 38 in the second closing element 36. In the valve lower part 19 formed as a sleeve, a second valve seat 34 is formed along the second through-opening 33. Alternatively, the second valve seat 34 can also be formed along the second fluid opening 19.2 made in the sleeve-shaped valve lower part 19. By the axial movement of the second closing element 36, the second valve seat 34 and thus the main stage 30 can be opened or closed. The sleeve-shaped valve lower part 19 can in particular be made as a multi-stage deep-drawn part. The pre-stage capsule 22 and the second closing element 36 project into the valve lower part 19, so that the second closing element 36 can enter into a sealing cooperation with the second valve seat 34. The valve lower part 19 has a second fluid opening 19.2 at its free end. The valve lower part 19 is then arranged in a fluid block, not shown. As can be further seen from FIGS. 1 to 3, a plurality of first fluid openings 19.1 are made as radial holes in the outer casing surface of the valve lower part 19. In addition to this, a radial filter 5 is arranged in the region of the first fluid openings 19.1, which can capture relatively large dirt particles. The valve 1 can be crimped in the fluid block via a crimping plate 7.

[0023] In the embodiment shown, the pre-capsule 22 is firmly pressed with its open end against the connection area 16.1 of the magnetic armature 16. Alternatively, the connection of the pre-capsule 22 to the connection area 16.1 of the magnetic armature 16 can also be formed as a welded or screwed joint.

[0024] As can be further seen from Figures 1 to 3, the magnet assembly 3 comprises a cover-like casing mantle 3.1, a winding support 3.2 on which the coil winding 3.3 is placed, and a cover plate 3.4 closing the open side of the casing mantle 3.1. The valve cartridge 10 has its pole core end at least partially inserted into the magnet assembly 3, with the upper end of the magnet assembly 3 abutting against the pole core 14 and the lower end of the magnet assembly 3 abutting against the valve sleeve 12. The magnet assembly 3 generates a magnetic field by energizing the coil winding 3.3, which moves the magnetic armature 16 against the force of the return spring 17.

[0025] Instead of having to traverse the pre-stage stroke hV to open the main stage 30, as in conventional two-stage solenoid valves, in the embodiment of the two-stage solenoid valve 1 according to the invention, the full stroke hG of the magnetic armature 16 is utilized to open the pre-stage 20 or the main stage 30. In contrast to conventional solenoid valves, the full stroke hG of the magnetic armature 10 can therefore be adjusted to be much smaller. This results in a much smaller operating gap 18 between the magnetic armature 16 and the pole core 14, which results in a much larger magnetic force. In this case, in order that the second closing element 36 is not pressed into the second valve seat 34 in the closing direction by the fluid forces when flowing through the two-stage solenoid valve 1 and the main stage 30 is closed, the spring force of the spring element 28 is pre-set to be greater than in the case of conventional two-stage solenoid valves. However, when opening, the stronger spring force of the spring element 28 must be overcome. However, this additional expenditure of force is more than compensated for by the larger magnetic force. As can be further seen from FIGS. 2 and 3, in the illustrated embodiment, the magnetic armature 16 directly abuts the pole core 14 in the open state, which can reduce holding current. [Explanation of symbols]

[0026] 1 Solenoid valve 3 Magnet Assembly 3.1 Casing 3.3 Coil Winding 10 Valve Cartridge 12 Valve sleeve 14 Pole Core 16 Magnetic Armature 16.1 Connection Area 17 Return spring 18 Operating gap 19 Lower part of valve 19.1 First fluid opening 19.2 Second fluid opening 20 First stage 22 Capsules 23 Aperture 24 First valve seat 26 First closing element 28 Spring elements 30 Main Stage 32 Ring-shaped valve body 34 Second valve seat 36, 26a Second closing element 36.2 Stopper 36.2A Stopper shoulder 36A Seal bush 38 Through hole 39 Inflow opening 42 Axial clearance hG Full stroke hV Front stroke

Claims

1. The valve cartridge comprises a magnet assembly (3) and a valve cartridge (10), the valve cartridge comprising a pole core (14), a magnetic armature (16) axially movable between a closed position and an open position against the force of a return spring (17) by a magnetic force generated by the magnet assembly (3) in a valve sleeve (12), at least one first fluid opening (19.1), at least one second fluid opening (19.2), a front stage (20) having a first valve seat (24) and a first closing element (26), and a main stage (30) having a larger second valve seat (34) and a second closing element (36), the magnetic armature (16) being connected to the first closing element (26) and via a spring element (28) to the first closing element (26). In a two-stage solenoid valve (1) in which a relative movement between the first and second closing elements (26, 36) is possible against the repulsive force of the spring element (28), the movement being limited by an adjustable pre-stage stroke (hV), and an adjustable working gap (18) between the magnetic armature (16) and the pole core (14) pre-determines the total stroke (hB) of the magnetic armature (16), the magnetic armature (16) opens the pre-stage (20) or the main stage (30) respectively with the same total stroke (hG) during its opening movement, the pre-stage stroke (hV) being adjusted to be greater than the total stroke (hG) of the magnetic armature (16), the magnetic armature (16) displaces the first closing element (26) from the first valve seat (24) when a current pressure difference (P1-P2) between the at least one first fluid opening (19.1) and the at least one second fluid opening (19.2) is greater than a threshold value, and the spring element (28) displaces the second closing element (36) from the second valve seat (34) after pressure compensation between the at least one first fluid opening (19.1) and the at least one second fluid opening (19.2), opening the main stage (30) and closing the front stage (20); The spring force of the spring element (28) is greater in a closing direction than a corresponding fluid force when flowing through the second valve seat (34) and is preset to hold the main stage (30) in an open state.

2. A valve cartridge (10) comprising a magnet assembly (3) and the valve cartridge comprising a pole core (14), a magnetic armature (16) axially movable between a closed position and an open position against the force of a return spring (17) by a magnetic force generated by the magnet assembly (3) within a valve sleeve (12), at least one first fluid opening (19.1), at least one second fluid opening (19.2), a front stage (20) having a first valve seat (24) and a first closure element (26), and a main stage (30) having a larger second valve seat (34) and a second closure element (36), the magnetic armature (16) being connected to the first closure element (26) and via a spring element (28). In a two-stage solenoid valve (1) in which a relative movement between the first and second closing elements (26, 36) is possible against the repulsive force of the spring element (28), the movement being limited by an adjustable pre-stage stroke (hV), and an adjustable working gap (18) between the magnetic armature (16) and the pole core (14) pre-determines the total stroke (hB) of the magnetic armature (16), the magnetic armature (16) opens the pre-stage (20) or the main stage (30) respectively with the same total stroke (hG) during its opening movement, the pre-stage stroke (hV) being adjusted to be greater than the total stroke (hG) of the magnetic armature (16), the magnetic armature (16) displaces the second closing element (36) from the second valve seat (34) and opens the main stage (30) while keeping the front stage (20) closed if a current pressure difference (P1-P2) between the at least one first fluid opening (19.1) and the at least one second fluid opening (19.2) is equal to or less than a threshold value; The spring force of the spring element (28) is greater in a closing direction than a corresponding fluid force when flowing through the second valve seat (34) and is preset to hold the main stage (30) in an open state.

3. An solenoid valve (1) as described in claim 1 or 2, characterized in that the first valve seat (24) is arranged in a first axial through opening (38) of the second closure element (36).

4. An solenoid valve (1) as described in any one of claims 1 to 3, characterized in that the second closure element (36) is at least partially arranged in a front-stage capsule (22) and the first valve seat (34) is arranged within the front-stage capsule (22).

5. An electromagnetic valve (1) as described in claim 4, characterized in that the pre-stage capsule (22) is firmly connected at its open end to the connection area (16.1) of the magnetic armature (16).

6. The solenoid valve (1) as described in claim 5, characterized in that the second closure element (36) has an end portion facing away from the magnetic armature (16) that passes through an axial opening (23) of the front capsule (22) and is supported by the edge (23.1) of the opening (23) in the front capsule (22) via the spring element (28).

7. An solenoid valve (1) as described in claim 6, characterized in that a stopper (36.2) is formed on the second closure element (36), and the distance between the stopper (36.2) of the second closure element (36) and the edge (23.1) of the opening (23) in the pre-stage capsule (22) determines the pre-stage stroke (hV).

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