Electromagnetic valve and internal combustion engine cooling system with electromagnetic valve

Abstract

A solenoid valve (1), in particular for closing a bypass in a coolant circuit of an internal combustion engine, with an energizable winding (3) and an armature (2) that is adjustable in the direction of a core by energizing the winding, which armature (2) force-loads a valve plunger (8) with energized winding (3) in the direction of a closing position, in particular against the spring force of a resetting spring (18), wherein when the armature (2) is energized a pin (12) which is adjustable together with the armature for adjusting the valve plunger (8) in the direction of the closing position is provided, by way of which the valve plunger (8) by way of adjusting the armature (2) upon energization can be force-loaded in the direction of the closing position, and which is spring force-loaded by a pressure limiting spring (13) in the direction of the closing position of the valve plunger (8) and which by way of the valve plunger (8) upon an axial valve plunger movement of the valve plunger (8) out of its closing position is adjustable for opening the solenoid valve (1) despite the armature (2) that is adjustable in the direction of the core (6) against the spring force of the pressure limiting spring (13).

Claims

1. A solenoid valve (1) for closing a bypass in a coolant circuit of an internal combustion engine, with an energizable winding (3) and an armature (2) that is adjustable in the direction of a core by energizing the winding, which armature (2) force-loads a valve plunger (8) in the direction of a closing position against the spring force of a resetting spring (18) when the winding (3) is energized, wherein a pin (12) is adjustable together with the armature for adjusting the valve plunger (8) in the direction of the closing position when the armature (2) is energized, whereby the valve plunger (8) can be force-loaded in the direction of the closing position, wherein the pin (12) is spring force-loaded by a pressure limiting spring (13) in the direction of the closing position of the valve plunger (8), whereby the valve plunger (8) is adjustable out of its closing position against the spring force of the pressure limiting spring (13) for opening the solenoid valve (1) despite the armature (2) being force-loaded in the direction of the core (6), wherein a magnetic flux circuit of the winding (3) and the pressure limiting spring (13) are designed so that in the case of a control voltage that is minimally necessary for closing the solenoid valve, the closing force exerted on the valve plunger (8) via the armature (2) is lower than the spring force exerted on the valve plunger (8) by the pressure limiting spring (13) and with a maximum control voltage, and a limit voltage between the minimum control voltage and the maximum control voltage, the closing force exerted on the valve plunger (8) by way of the armature (2) is greater than the spring force exerted on the valve plunger (8) by way of the pressure limiting spring (13).

2. The solenoid valve (1) according to claim 1, wherein means for maintaining a minimum pressures limiting spring preload are provided.

3. The solenoid valve (1) according to claim 1, wherein the pin (12) is arranged in an armature bore (11) of the armature (2).

4. The solenoid valve (1) according to claim 3, wherein the pressure limiting spring (13) spring force-loads the pin (12) against a pin stop (16) formed on the armature (2).

5. The solenoid valve (1) according to claim 3, wherein the pressure limiting spring (13) is arranged within the armature bore (11).

6. The solenoid valve (1) according to claim 5, wherein the pressure limiting spring (13) supports itself on the side facing away from the pin (12) on an abutment element (15) that is fixed in or on the armature (2), by way of the axial position of which relative to a pin stop (16) in the armature (2) the preload of the pressure limiting spring (13) is adjustable.

7. The solenoid valve (1) according to claim 1, wherein the pin (12) and the compression spring (13) are arranged in a cage that is arranged between the armature (2) and the valve plunger (8) for limiting a maximum elongation of the pressure limiting spring (13), wherein the cage with the valve plunger (8) located in the closing position is adjusted, at least in portions, axially into the core.

8. The solenoid valve (1) according to claim 7, wherein the pressure limiting spring (13) on the side facing away from the pin supports itself on an abutment element, fixed on or in the cage (22), through the axial position of which relative to a pin stop (16) in the cage (22) the preload of the pressure limiting spring (13) is adjustable.

9. The solenoid valve (1) according to claim 1, wherein a spring force of the pressure limiting spring (13) with the armature (2) adjusted in the direction of the core and the valve plunger (8) located in the closing position is greater than the spring force of the resetting spring (18).

10. The solenoid valve (1) according to claim 1, wherein the pin (12) supports itself directly on the valve plunger (8).

11. The solenoid valve (1) according to claim 1, wherein the valve plunger (8) interacts with a closing body (9) which by the valve plunger (8) in its closing position is pressed against a valve seat.

12. The solenoid valve (1) according to claim 1, wherein the solenoid valve (1) is voltage controlled.

13. The solenoid valve (1) according to claim 1, wherein the armature (2) with minimal voltage for closing the solenoid valve (1) with the valve plunger (8) in the closing position is spaced from the core (6) by way of a residual air gap or supports itself, with maximum permissible voltage, on the core (6), by way of a non-stick disc (19) or non-stick groove.

14. An internal combustion engine cooling system (23) with a cooling medium pump (24) and with a slide (25) for switching over between a small and a large coolant circuit, wherein the slide (25) is hydraulically actuatable by way of a cooling medium pressure in a switching chamber (26) and wherein a solenoid valve (1) according to claim 1 closes a bypass to a coolant tank, with the valve plunger (8) located in the closing position for increasing the cooling medium pressure and wherein, when there is an impermissibly high cooling medium pressure in the switching chamber (26), and despite energized winding (3) and an armature (2) adjusted in the direction of the core (6), because of the force exerted by the cooling medium, by way of a valve closing body, on the valve plunger against the spring force of the pressure limiting spring (13), the pin (12) moves out of the closing position to open the solenoid valve (1) and thereby open the bypass.

15. An internal combustion engine according to claim 14, wherein the solenoid valve (1), the slide (25) and the cooling medium pump (24) are arranged in a common cast metal housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features and details of the invention are obtained from the following description of preferred exemplary embodiments and by way of the drawings.

(2) These show in:

(3) FIG. 1a a solenoid valve designed according to the concept of the invention in the dropped-out state,

(4) FIG. 1b a detail X from FIG. 1a,

(5) FIG. 2a the solenoid valve according to FIG. 1a in the energized yet, because of its pressure limiting functionality, in the opened state,

(6) FIG. 2b a detail X from FIG. 2a,

(7) FIG. 3 greatly schematically an alternative embodiment, in which a pressure limiting spring and a pin are not integrated in the armature as in the preceding exemplary embodiments, but arranged in a cage that is provided between the armature and the valve plunger,

(8) FIG. 4 highly schematically, an internal combustion engine cooling system with a solenoid valve designed according to the concept of the invention in a merely hinted state.

DETAILED DESCRIPTION

(9) In the figures, same elements and elements with the same function are marked with the same reference characters.

(10) In FIGS. 1a and 1b, a voltage-controlled solenoid valve 1 is shown, preferably for use in an internal combustion engine cooling system, as exemplarily shown in FIG. 4.

(11) The solenoid valve 1 comprises an armature 2, which is axially adjustable along a longitudinal axis L (adjusting axis) by energizing an electrical winding 3, which is arranged on a coil holder 4, namely in the direction of a valve seat 5. In FIGS. 1a and 1b, the dropped-out state is shown, i.e. a state in which the winding 3 is not energized or the applied control voltage is not sufficient to adjust the armature 2 axially along the longitudinal axis L towards a core 6.

(12) From FIG. 1a it is evident that the armature 2 is longitudinally adjustably guided in an armature guiding pot 7, into which the core 6 is pushed.

(13) The core 6 is axially penetrated by an elongated valve plunger 8 which extends along the longitudinal axis L, which, with its end facing away from the armature 2, interacts with a closing body 9 designed as a ball in this case and presses the same into its valve seat 5 when the winding 3 is energized, thereby closing a fluid line 10, in this case specifically a bypass.

(14) As is directly evident from FIGS. 1a and 1b, the armature 2 does not directly interact with the valve plunger 8 but by way of a pin 12 which is adjustable within the armature 2, more precisely within a central armature bore 11 (passage opening) along the longitudinal axis L, which pin 12 is spring force-loaded in the direction of a closing position of the valve plunger 8, i.e. in the direction of the valve seat 5 which is likewise received in the armature bore 12.

(15) The pressure limiting spring 13 supports itself with its end facing away from the pin 12 on an abutment element 15, which is designed here as press-in bush, which is axially pressed into the armature bore 11 (a central bore) from the back, i.e. from a side facing away from the pin 12. The press-in depth in this case determines the preload of the pressure limiting spring 13.

(16) Viewing it together it is evident that within the armature 2 on a side of the pin 12 facing away from the pressure limiting spring 13 a pin stop 16 designed as annular shoulder is realised within the armature 2 in order to limit the relative adjusting movement of the pin 12 relative to the armature 2 in the direction of the valve seat 5.

(17) The pin 12 axially supports itself on a thickened end 17 of the valve plunger 8 and thus adjusts the valve plunger 8 upon adequate energizing of the winding 3 in the direction of a closing position, i.e. in the direction of the valve seat 5.

(18) The aforementioned adjusting movement is counteracted by a resetting force 18, which supports itself on an annular face of the valve plunger 8 facing away from the pin 12, in the specific example of the end 17. The pressure limiting spring 13 in this case is designed stronger than the resetting spring 18.

(19) To optimise the magnetic flux circuit, armature 2 and core 6 interact by way of conical faces, wherein for avoiding sticking of the armature 2 on the core 6 suitable non-stick means 19, for example a non-stick disc or grooving can be provided.

(20) When an adequate control voltage is applied to the solenoid winding 3, a magnetic force acts on the armature 2 so that the same is adjusted in a position shown in FIGS. 2a and 2b in the direction of the core, i.e. in the direction of the valve seat 5. The magnetic flux in this case runs via a metallic housing 20 and the armature guiding pot 7 into the armature 2 and through the same axially in the direction of the core 6, wherein an axial air gap between armature 2 and core 6 is overcome and the magnetic flux in the drawing plane within the core 6 runs further down to a yoke plate 21 and within the same radially to the outside again into the pot-like or yoke-like metal housing 20.

(21) By adjusting the armature 2 in the axial position shown in FIGS. 2a and 2b, the pin 12 presses along the longitudinal axis L against the valve plunger 8 in the direction of its closing position, as a result of which the same with adequately low pressure in the fluid line 10 or below the valve seat 5, closes the valve or the fluid line 10.

(22) When the compressive force within the fluid line 10 rises (i.e. in a region in front of the valve seat) to a value that is greater than the closing force resulting from the magnetic force and the resetting spring force, the armature 2 is axially pressed from the valve seat 5 despite the energization of the winding 3 and the valve opens. Because of the provided pressure limiting functionality, the valve however also opens when the magnetic force with corresponding high control voltage is so high that the compressive force is not sufficient to axially adjust the closing body 9 and the valve plunger 8 including the armature 2 away from the core 6. For if the compressive force is sufficient in order to overcome the resulting force from the spring force of the pressure limiting spring 13 and the resetting spring 18, the closing body 9 and the valve plunger 8, with the armature adjusted in the direction of the core, are moved out of a closing position and the pressure limiting spring 13 is further preloaded through a resulting axial adjusting of the pin 12. The pin 12 in this case moves relatively axially within the and to the armature 2, which remains in its axial position. Because of this, impermissible excess pressures in the fluid line 10 can be avoided.

(23) The exemplary embodiment of a solenoid valve 1 according to FIG. 3 differs in principle from the previously explained embodiment in that the pin 12 and the pressure limiting spring 13 are not received in the armature 2 but in a cage 22 which is either fixed on the armature 2 or preferably separate from this, which is axially located between the armature 2 and the valve plunger 8.

(24) Located opposite, the resetting spring 18 supports itself in an axial bore on the core 6.

(25) The cage 22 prevents an impermissible elongation of the pressure limiting spring 13.

(26) On the side facing away from the pin 12, the pressure limiting spring 13 supports itself on an abutment element 15 fixed in the cage 22.

(27) The axial length of the exemplary embodiment according to FIG. 3 is greater than that of the exemplary embodiment described previously. The functionality however is the same in principle so that with respect to the function reference is made to the previous explanations.

(28) In FIG. 4, an internal combustion engine cooling system 23 is shown in a greatly schematic manner. This comprises a cooling medium pump 24 (circulating pump) for delivering cooling medium, in particular cooling water in two circuits.

(29) For switching over between the circuits a hydraulically actuatable slide 25 is provided, upstream of which a switching chamber 26 is arranged, into which cooling medium is continuously fed via a small pump 27 which is designed for example as a piston pump.

(30) With closed solenoid valve 1, i.e. with the closing body 9 bearing against the valve seat 5, the pressure in the switching chamber 26 rises as a consequence and the slide 25 is moved so that a small cooling medium circuit is switched open. For switching over to a large coolant circuit, the pressure in the switching chamber 26 has to be lowered. This can be realised for example by a suitably low, preferentially temperature-dependent control voltage on the solenoid valve 1, so that its armature is adjusted in an axial direction away from the valve seat 5 and thus opens the solenoid valve and thus opens a bypass to a cooling medium tank 28.

(31) When the control voltage applied to the solenoid valve 1 is high for example because of a high cooling medium temperature and the pressure in the switching chamber 26 rises but not so high that the armature 2 can be adjusted against the active magnetic force, the solenoid valve 1 opens nevertheless because of the realised pressure limiting functionality, in that the pressure limiting spring within the solenoid valve is further preloaded, because of an axial movement of the closing body 9, of the valve plunger 8 and of the pin 12, so that as a result the valve opens and pressure can be removed in the direction of the cooling medium tank 28.

(32) It is particularly practical when the solenoid valve, the slide for switching over between the cooling circuits, the cooling medium pump are arranged in a common housing that is preferentially formed as a cast metal housing, schematically illustrated in FIG. 4 at 40.