SOLENOID VALVE FOR A MOTOR VEHICLE AND METHOD FOR MANUFACTURING A MOTION UNIT COMPLETING AN ARMORED AND A VALVE UNIT FOR SUCH A SOLENOID VALVE

Description

[0001] The invention relates to an electromagnetic valve for a motor vehicle comprising a housing having an inlet and an outlet, a flow cross-section formed between the inlet and the outlet and surrounded by a valve seat, a one-piece valve unit with a coupling element and a control element that can be placed on and lifted off the valve seat, and an electromagnetic actuator with an armature having an axial through-bore into which the coupling element of the valve unit projects and which is movable with the armature, as well as a method for manufacturing a motion unit consisting of an armature and a valve unit for such an electromagnetic valve.

[0002] These types of solenoid valves have a wide range of applications. One notable use is as a coolant valve to shut off or release the flow of coolant in a vehicle's cooling circuit. Such an electromagnetic coolant valve typically has a control element made of plastic, which must be connected to a magnetizable armature, usually made of metal, to provide a coupling mechanism. This coupling allows the control element to be lowered onto or lifted from a valve seat by energizing the electromagnet. The coupling between the control element and the armature can be achieved via coupling elements and force-fit or positive-locking connections, with the coupling element material being either metal or plastic.It is known to design the control body with an axial projection which is fastened in a bore of the anchor by means of a press connection.

[0003] For example, DE 10 2012 010 140 A1 discloses an electromagnetic bypass valve in which the valve body is connected to the armature via a ball joint. To reduce switching times, this valve has through-holes in the control body and the armature, thus achieving pressure equalization between the side of the control body facing the valve seat and the side of the control body and armature assembly facing away from the valve seat. This prevents unintentional opening of the valve in the event of increased total pressure in the inlet port of the valve device and ensures insensitivity to pulsations. However, the connection of the armature to the control body is quite complex to manufacture, as the metallic armature must first undergo extensive machining to produce the ball joint and the through-holes.It also has a high weight compared to plastic parts, which also means a higher moment of inertia, leading to greater required actuating forces.

[0004] From EP 3 263 962 A1, an electromagnetic valve is known with a valve unit comprising a coupling element that extends through an opening in an armature plate and is attached to the armature plate by forming. Several additional elements are arranged between the control body of the valve unit and the armature plate.

[0005] From EP 1 717 501 A1, an electromagnetic valve is known with a valve unit which rests against the bottom of a pot-shaped armature and whose opposite end rests on the opposite side of the bottom and has an extension there.

[0006] Furthermore, EP 3 372 809 A1 discloses a spool valve whose valve unit has a coupling section with an external thread, via which the valve element is connected to an armature having a corresponding internal thread. A similar solenoid valve is known from US 5,961,052 A.

[0007] Additionally, an electromagnetic valve is known from GB 2 334 552 A, the valve element of which is fixed to the armature by means of a screw with a stop plate in between.

[0008] Accordingly, the disadvantage is that the known solenoid valves are too heavy, especially in the area of ​​the movement unit consisting of the armature and the control body, and are too expensive to manufacture, particularly if pressure equalization is to be provided at the movement unit.

[0009] The task is therefore to provide an electromagnetic valve suitable as a coolant valve, as well as a method for manufacturing an electromagnetic valve or the motion unit of the electromagnetic valve, which can reduce the manufacturing costs and weight of the valve and which also has pressure compensation via the motion unit in order to reduce the actuation times and required actuation forces.

[0010] This problem is solved by an electromagnetic valve for a motor vehicle with the features of main claim 1 and a method for manufacturing a motion unit from an armature and a valve unit for such an electromagnetic valve with the features of main claim 8.

[0011] Because the one-piece valve unit has an axial bearing surface against which the armature rests at its first axial end, and a separate fastening element rests at the second axial end of the armature, which is rigidly connected to the coupling element of the valve unit, the armature is clamped between the fastening element and the axial bearing surface of the valve unit. This ensures that the valve unit, along with the armature, is forced to move when the actuator coil is energized. Relative movement of the armature to the control element is thus prevented. The armature can therefore be manufactured from a simply shaped and thus cost-effective metal part, as it has a completely rotationally symmetrical, approximately hollow cylindrical shape. The control element can be manufactured cost-effectively from a plastic and is therefore lightweight.This allows the overall weight of the movement unit, consisting of the armature and the valve unit, to be reduced, which also reduces the actuating forces.

[0012] The fastening element is designed as a pin with a head that rests directly, or with the interposition of a ring, against the second axial end of the anchor, thus forming a second bearing surface on the anchor. This clamps the anchor from both axial sides, allowing the individual components to be manufactured with very large tolerances and making them easy to assemble.

[0013] Assembly is made particularly easy by the fact that the pin protrudes into a blind hole in the coupling link, as this can be used as a pre-fixing mechanism, thus preventing lateral movement between the pin and the coupling link. This avoids assembly errors.

[0014] The valve unit and the pin are made of plastic. The pin is connected to the coupling element by welding, specifically ultrasonic welding. This type of welding creates a permanent, material-bonded connection, thus ensuring the rigid connection between the valve unit and the armature.

[0015] Regarding the method, the problem is solved by inserting a coupling element of the valve unit into a through-hole in the armature until the armature rests with a first axial end on a bearing surface of the valve unit. Subsequently, a fastening element is inserted into the armature and a blind hole in the coupling element located in the armature from a side of the armature opposite a control body of the valve unit. The fastening element is then loaded towards a second axial end of the armature opposite the armature, so that the armature is pressed against the bearing surface of the valve unit. Finally, the fastening element is welded to the coupling element of the valve unit in this position. In this way, a tight fit of the armature between the fastening element and the bearing surface of the valve unit is ensured, thus guaranteeing backlash-free movement between the armature and the valve unit.The connection is simple to create and reliably prevents the valve unit from unintentionally detaching from the armature, even in the event of vibrations or pulsations, thanks to the material-bonded connection of the fastening element to the coupling link. The motion unit is thus manufactured cost-effectively.

[0016] Furthermore, a gap is preferably formed between the coupling element and the armature, and at least one recess is formed on the head of the pin or the ring arranged between the head and the armature. This recess connects the gap fluidically to a chamber located on the axial side of the armature opposite the control body. This allows fluid to flow from the gap to the rear of the armature via the at least one recess for pressure equalization. The size of the gap and the recesses must be adapted to the viscosity of the controlled fluid, ensuring that the movement of the actuator is not slowed down by the forced movement of the fluid when the armature is actuated. This allows for very fast response times with low actuating forces.

[0017] In a further development, the axial bearing surface on the valve unit has at least one recess through which the gap is fluidically connected to a space formed axially between the armature and the control body. This allows fluid to flow to the two opposite sides of the armature without having to flow through the very narrow gap between the armature and the guide sleeve. This gap, which must be very small to prevent tilting of the armature, does not allow for a sufficiently rapid fluid flow. The armature is thus pressure-balanced.

[0018] In a preferred embodiment, the axial bearing surface on the valve unit has three recesses that are arranged offset from each other by 120°, which on the one hand ensures a firm bearing of the armature on the valve unit and on the other hand also ensures a uniform flow through the gap between the armature and the valve unit with a sufficient available flow cross-section.

[0019] Furthermore, the space between the anchor and the control body is advantageously continuously fluidically connected to the inlet via through-openings in the control body. This ensures complete pressure and force equalization with respect to the hydraulic forces across the entire motion unit, since the inlet pressure prevails across the entire unit.

[0020] It is also advantageous if a spring is arranged in the actuator, via which the armature with the valve unit is biased towards the valve seat, with a first axial end of the spring resting against the head of the pin or the ring between the armature and the head of the pin. The spring moves the valve into a safety position in the event of actuator failure, thus ensuring, for example, a coolant flow when used as a coolant valve. The pin serves as a support for the spring, so that wear of the armature is not a concern.

[0021] In a further embodiment, an axial section of the head of the pin is radially surrounded by the spring, allowing the head to act as a guide section for the spring, thus reliably preventing displacement or buckling of the spring.

[0022] This results in a solenoid valve that is balanced with respect to hydraulic forces in all positions and exhibits short response times. This is further enhanced by the low weight of the actuator, which can be manufactured particularly cost-effectively and easily due to the use of many lightweight plastic components.

[0023] An embodiment of an electromagnetic valve according to the invention is shown in the figures and is described below using an embodiment as a coolant valve. Figure 1 shows a side view of an electromagnetic valve according to the invention in a cutaway view. Figure 2 shows a perspective view of a section of the motion unit of the solenoid valve. Figure 1 .

[0024] The in Figure 1The coolant valve shown consists of a housing 10, which is designed in two parts and has a flow housing 12 with a flow channel 14 formed therein and an actuator housing 16 attached to the flow housing 12, in which an electromagnetic actuator 18 is arranged.

[0025] The electromagnetic actuator 18 comprises an electromagnetic circuit consisting of a coil 20 wound on a coil carrier 22 and energized via a connector 24, a magnetizable core 26, return elements 28, a yoke 30, and a movable armature 32. When the coil 20 is energized, the armature 32 is moved in the direction of the core 26 by the resulting magnetic forces in a known manner.

[0026] The armature 32 forms a motion unit 40 with a valve unit 34, which is made of plastic and consists of a control body 36 and a coupling element 38. For this purpose, the armature 32 has an axial through-bore 42 into which the coupling element 38 projects. The coupling element 38 is designed as a cylindrical projection of the control body 36 and has a shorter axial length than the through-bore 42 of the armature 32, as well as a slightly smaller diameter, so that a gap 44 is formed between the coupling element 38 and the armature 32 in the through-bore 42. An axially extending blind hole 46 is formed at the axial end of the coupling element 38 projecting into the through-bore 42. According to the invention, a fastening element 48 is inserted into this blind hole and attached to the coupling element 38.

[0027] In the present embodiment, the fastening element 48 consists of a plastic pin 50 with a head 52 of enlarged diameter. To fasten the valve unit 34 to the armature 32, the coupling element 38 is first pushed into the through-bore 42 of the armature 32 until the first axial end 54 of the armature 32, pointing towards the control body 36, abuts an axial bearing surface 56 of the valve unit 34, which is designed as a shoulder of the coupling element 38, so that the coupling element 38 extends from this bearing surface 56 with an enlarged diameter towards the control body 36.

[0028] The contact surface 56 has three recesses 58 arranged at 120° intervals, thus providing a fluidic connection between the gap 44 and a space 60 located between the anchor 32 and the control body 36. Naturally, more or fewer recesses 58 can be provided, with appropriate flow cross-sections to ensure rapid flow depending on the viscosity of the fluid.

[0029] After the valve unit with its coupling element 38 is pushed into the through-bore 42 and against the bearing surface 56, the pin 50, with its head 52 or with a ring 61 surrounding the pin 50 and bearing axially against the head 52, is pressed against the second axial end 62 of the armature 32. In doing so, the pin 50 enters the blind hole 46 of the coupling element 38. In this position, the armature 32 is axially clamped between the head 52 of the pin 50 and the bearing surface 56, so that no axial relative movement of the armature 32 with respect to the valve unit 34 is possible. In this position, the pin 50 is welded to the coupling element 38 by ultrasonic welding and thus secured.

[0030] The head 52 of the pin 50 or the intermediate ring 61 has at least one further recess 64, through which a space 66 on the side of the anchor 32 opposite the control body 36, namely between the anchor 32 and a sleeve 68 in which the anchor 32 is guided, is continuously fluidically connected to the gap 44 between the anchor 32 and the coupling element 38.

[0031] The sleeve 68, in which the armature 32 is guided, also receives the core 26 and extends radially inside the actuator 18 to a housing projection 70 of the actuator housing 16, which extends axially into the flow housing 12. An O-ring 72 is arranged between this housing projection 70 and an end region of the sleeve 68, sealing the radially outer region of the sleeve 68 against the conveyed coolant, so that no coolant can reach the coil 20.

[0032] Furthermore, the sleeve 68 defines the space 60, which is formed on a side of the control body 36 facing away from an inlet 74 of the flow housing 12 and axially between the control body 36 and the armature 32, and which is sealed against a radial outlet 76 of the flow housing 12 by means of a lip seal 78, the closed side of which faces the outlet 76. The lip seal 78 moves with the control body 36 and is fastened via its inner leg in a radial groove 80 of the control body 36, with its outer leg bearing against the sleeve 68. Axially, the closed side of the lip seal 78 rests on a bearing surface 82 of the control body 36, which is designed as a circumferential radial projection on the control body 36.

[0033] Chamber 60 is continuously connected to inlet 74 via through-openings 84 formed in the control body 36, which are designed as axial through-bores. This connection of inlet 74 to chamber 60 is not entirely axial via the through-openings 84, as the ends of the through-openings 84 are largely covered by a particle shield 86, which is formed centrally at the end of the control body 36 facing inlet 74. Accordingly, the flow into the through-openings 84 initially occurs between the particle shield 86 and an axially extending annular projection 88, which allows the control body 36 to be mounted on a valve seat 90. From here, the flow is first deflected radially inwards into the through-openings 84 and from there axially into chamber 60.

[0034] In addition, a connection exists via the recesses 58 on the bearing surface 56 of the valve unit 34 to the gap 44 between the armature 32 and the coupling element 38, and via the recesses 64 on the head 52 of the pin 50, a continuous fluidic connection exists to the space 66 formed by the sleeve 68 and the armature 32 on the side of the armature 32 opposite the control body 36. The motion unit 40 is thus pressure-balanced. Since, in addition, the total area of ​​the control body 36 radially within the valve seat 90 at the inlet 74 is equal to the sum of the areas on the armature 32 and on the control body 36, on which the fluid pressure acts in opposite directions, there is also hydraulic force balance, which leads to easy actuation of the solenoid valve.Accordingly, the motion unit 40 is balanced in all positions with respect to the hydraulic forces by the existing connections between the front and back sides of the valve unit 34 and the armature 32, since the fluid can quickly flow from the inlet 74 to the opposite side of the motion unit 40 via the recesses 58, 64, the through-openings 84 and the gap 44, which would not be possible at a sufficient speed via the gap between the sleeve 68 and the armature 32, as this must be designed with a tight clearance to prevent the armature 32 from tilting.

[0035] The only force that the actuator 18 must overcome when opening or closing the valve is therefore the force of a spring 92, which biases the motion unit 35 in a direction away from the core 26. This forces the control element 36 onto the valve seat 90, which is formed in the flow housing 12 between the axial inlet 74 and the radial outlet 76. When the coil 20 is energized, the magnetic force exceeds the force of the spring 92, lifting the control element 36 from the valve seat 90 and thus opening the flow cross-section. In the event of a failure of the actuator 18, an open safety position of the solenoid valve is thus established.

[0036] The spring 92 bears against a shoulder of the head 52 of the pin 50 with its first axial end 94, so that an axial section 96 of the head 52 with a smaller diameter projects into the interior of the spring 92, which is supported at its opposite axial end against the core 26. Thus, the head 52 forms, on the one hand, a bearing surface for the spring 92 and, on the other hand, a guide in the lower region, thereby preventing the spring 92 from shifting.

[0037] The solenoid valve according to the invention ensures rapid adjustability with low actuating forces and is also very easy to manufacture, since the individual parts can be produced with large tolerances and many plastic parts can be used, which can be manufactured easily and cost-effectively, even with complex shapes, using the injection molding process. In addition, the solenoid valve is lightweight due to the high proportion of plastic. Furthermore, the armature, due to its simple shape, can be manufactured with minimal effort, which also results in cost savings.

[0038] It should be clear that the scope of protection of the present main claim is not limited to the described embodiment. The bearing surfaces and recesses on the head or the coupling element, as well as the coupling element itself, can be shaped differently or their number varied. A separate ring can also be used between the head and the anchor, in which the recess would then also be formed. Further design modifications are, of course, also conceivable.

Claims

1. A solenoid valve for a motor vehicle with a housing (10), which has an inlet (74) and an outlet (76), a through-flow cross-section, which is formed between the inlet (74) and the outlet (76) and is surrounded by a valve seat (90), a one-piece valve unit (34) with a coupling member (38) and a control body (36), which is able to be placed onto the valve seat (90) and is able to be lifted from the valve seat (90), an electromagnetic actuator (18) with an armature (32), which has an axial through-bore (42), into which the coupling member (38) of the valve unit (34) projects, which is movable with the armature (32), wherein the one-piece valve unit (34) has an axial contact surface (56), against which the armature (32) rests with its first axial end (54), wherein at the second axial end (62) of the armature (32) a separate fastening element (48) rests, which is securely connected with the coupling member (38) of the valve unit (34), the fastening element (48) is a pin (50) with a head (52), which lies directly or with interposition of a ring (61) against the second axial end (62) of the armature (32), the pin (50) projects into a blind hole (46) of the coupling member (38), characterized in that the valve unit (34) and the pin (50) are made of plastic and the pin (50) is connected to the coupling member (38) by welding, in particular by ultrasonic welding.

2. The solenoid valve for a motor vehicle according to Claim 1, characterized in that a gap (44) is formed between the coupling member (38) and the armature (32), and at the head (52) of the pin (50) or the ring (61) arranged between the head (52) and the armature (32) at least one recess (64) is formed, via which the gap (44) is continually connected fluidically with a space (66) which is formed at the second axial end (62) of the armature (32) opposed to the control body (36).

3. The solenoid valve for a motor vehicle according to Claim 2, characterized in that the axial contact surface (56) on the valve unit (34) has at least one recess (58) via which the gap (44) is fluidically connected with a space (60), which is formed axially between the armature (32) and the control body (36).

4. The solenoid valve for a motor vehicle according to Claim 3, characterized in that the axis contact surface (56) on the valve unit (34) has three recesses (58), which are arranged offset by 120° with respect to one another.

5. The solenoid valve for a motor vehicle according to Claim 3 or 4, characterized in that the space (60) between the armature (32) and the control body (36) is continually connected fluidically with the inlet (74) via through-openings (84) in the control body (36).

6. The solenoid valve for a motor vehicle according to one of the preceding claims, characterized in that in the actuator (18) a spring (92) is arranged, via which the armature (32) is loaded with the valve unit (34) in the direction of the valve seat (90), wherein a first axial end (94) of the spring (92) rests against the head (52) of the pin (50) or against the ring (61) between the armature (32) and the head (52) of the pin (50).

7. The solenoid valve for a motor vehicle according to Claim 6, characterized in that an axial portion (96) of the head (52) of the pin (50) is radially surrounded by the spring (92).

8. A method for the production of a movement unit (40) of an armature (32) and of a valve unit (34) for a solenoid valve, in which a coupling member (38) of the valve unit (34) is inserted into a through-bore (42) of the armature (32) until the armature (32) rests with a first axial end (54) on a contact surface (56) of the valve unit (34), subsequently, from a side of the armature (32) opposed to a control body (36) of the valve unit (34), a fastening element (48) is inserted into the armature (32) and a blind hole (46) of the coupling member (38) arranged in the armature (32), then the fastening element (48) is loaded in the direction of an opposed second axial end (62) of the armature (32), so that the armature (32) is pressed against the contact surface (56) of the valve unit (34), and finally the fastening element (48) is fastened in this position on the coupling member (38) of the valve unit (34) by welding.