Closure lid with a pressure-controlled or temperature-controlled directional control valve for an expansion tank and cooling system of an internal combustion engine

Abstract

A closure lid for an expansion tank of a cooling system of an internal combustion engine has integrated therein a directional control valve that decouples the expansion tank from the cooling circuit by pressure control or temperature control and integrates the expansion tank again into the cooling circuit after the internal combustion engine has reached its operating temperature.

Description

For cooling the waste heat produced in operation of internal combustion engines, water cooling is accepted practice in automobiles as well as in commercial vehicles.

The most important components of such water cooling are the water jacket of the internal combustion engine itself, a circulation pump, referred to also as water pump, an air-cooling agent cooler, a cooling agent expansion tank, and a thermostat.

In FIG. 7, such a cooling system is illustrated in a greatly simplified and schematic way.

The cooling agent expansion tank, in the following also referred to as expansion tank, has several functions. On the one hand, it serves to reliably separate gas bubbles generated during cavitation primarily at the suction side of the pump.

Also, the air volume in the expansion tank serves to enable fast pressure build-up upon heating and expansion of the cooling agent and to prevent escape of cooling agent when shutting down.

Because today's cooling systems are operated with overpressure, the expansion tank is closed off by a closure cap or a lid that, upon surpassing the permissible maximum pressure, enables blow-off into the environment. A further function of this closure lid resides in that opening of the expansion tank is to be prevented as long as the temperature of the cooling agent is elevated and, as a result of this, also the pressure of the cooling agent is significantly higher than the ambient pressure.

For environmental protection reasons and reasons of convenience, there is the desire to provide a cooling system that upon cold start of the internal combustion engine enables heating of the internal combustion engine as quickly as possible. This reduces fuel consumption in the cold start phase, and emissions in the cold start phase are also significantly reduced. A further goal is to be able to heat as quickly as possible the interior of the vehicle.

The invention has the object to provide a closure lid and a cooling system of an internal combustion engine which support these goals.

This object is solved according to the invention by a closure lid according to claim 1.

Advantageous configurations of the directional control valve according to the invention and its integration into the closure lid are claimed in the dependent claims and will be explained in detail in the following in the drawings and their description.

Because the directional control valve according to the invention opens with its outlet into the expansion tank, the expansion tank is separated hydraulically from the rest of the cooling system until the cooling water circulating in the rest of the cooling system has reached a certain minimum temperature and, as a result thereof, a predetermined overpressure is established in the cooling system.

As long as the minimum temperature or the overpressure has not yet been reached, the directional control valve is closed and the volume of the cooling agent circuit is reduced in the cold start phase by the contents of the expansion tank so that the “active” part of the cooling system and the internal combustion engine will heat up faster.

The advantage of a pressure-controlled directional control valve is to be viewed in that, independent of the positioning of the expansion tank, the pressure at the inlet side of the directional control valve corresponds to the pressure which is present in the cooling system. Accordingly, the pressure is a very direct and reliable criterion for opening the directional control valve after reaching operating temperature. Of course, it is also possible to use a temperature-controlled directional control valve in the closure lid instead of a pressure-controlled directional control valve.

In the embodiment illustrated in the Figures, it is advantageous when the pressure spring is supported with one end at a spring plate fixedly secured within the housing and the pressure spring is supported with the other end at the valve member.

In a service position of the lid, the entire directional control valve is moved out from a seal-tight contact with a housing so that the cooling water can bypass the directional control valve. By integration of the directional control valve in the closure lid, this functionality is realized without any additional costs.

In other words, when the cover is tightly screwed on and a pressure build-up in the cooling system is thus possible, the directional control valve according to the invention opens only at the time when a constructively predetermined overpressure in the system exists.

It has been found in many situations to be advantageous when the sealing seat is designed as a plate seat. In this way, the manufacture is simplified, a satisfactory seal-tightness is also achieved, and the directional control valve according to the invention is robust with regard to smaller contaminations or deposits.

Further advantages and advantageous embodiments can be taken from the following drawings, their description, and the claims.

Drawings

It is shown in:

FIG. 1 a longitudinal section of a first embodiment of a pressure-controlled directional control valve according to the invention in the closed state;

FIG. 2 the pressure-controlled directional control valve in the open state;

FIG. 3 the closure lid in the service position; and

FIG. 4 a schematic illustration of a cooling system of an internal combustion engine.

DESCRIPTION OF THE EMBODIMENTS

In FIG. 1, a part of an expansion tank 1 with screwed-on safety closure lid 2 is illustrated in section. The safety closure lid 2 comprises in the upper part an overpressure valve, an underpressure valve, and an unscrewing safety (no reference character) that will not be explained in more detail.

In connection with the invention, it is however important that the lid 2 is screwed into a socket 1a of an expansion tank 1. In FIG. 1, the so-called closed position is reached. This means that the lid 2 can no longer be screwed any deeper into the socket (without reference character) of the expansion tank 1.

In the closed position, the lid 2 seals the expansion tank 1 relative to the environment. The safety valve (no reference character) integrated into the lid 2 opens only when a pre-adjusted overpressure is reached in order to avoid impermissibly high pressure loads of the cooling system. Alternatively, the directional control valve can also open temperature-dependent.

In the lower section of the lid 2 in FIG. 1, a pressure-controlled directional control valve 8 according to the invention is integrated.

The directional control valve 8 is integrated into a housing 4 which is part of the lid 2. The housing 4 delimits together with the socket 1a of the expansion tank 1 an annular space 5. A bypass line 6 that is part of the cooling circuit of the internal combustion engine (see FIG. 4) opens into the annular space 5. The annular space 5 is delimited by two O-ring seals 10 and 12. The section of the housing 4 between the O-rings 10 and 12 is identified by reference character 13.

The directional control valve 8 is arranged in a recess 14 in the interior of the housing 4.

At a step (no reference character) of the recess 14 there is an annular valve seat 16. The valve seat 16 interacts with a cup-shaped valve member 18. At a collar or web 20 of the valve member 18, a sealing edge 22 is formed which interacts with the valve seat 16.

In the cup of the valve member 18, a pressure spring 24 is inserted that is supported on a spring plate 26. The spring plate 26 is connected fixedly with the housing 4.

The closed position illustrated in FIG. 1, the pressure spring 24 forces the valve member 18 with its sealing edge 22 against the valve seat 16 and interrupts the hydraulic connection between the bypass line 6 and the expansion tank 1. The bypass line 6 is connected hydraulically with the inlet of the directional control valve 8 while the outlet of the directional valve 8 is connected with the expansion tank 1.

Reference character 28 identifies a hydraulic connection between the annular space 5 and the part of the recess which is arranged in FIG. 1 above the valve member 18.

Because of the hydraulic connection 28, the same pressure is acting on the valve member 18 as in the annular space 5 and in the bypass line 6. The thus resulting hydraulic force counteracts the force which is exerted by the pressure spring 24. When the hydraulic force that is acting on the valve member 18 is greater than the force of the pressure spring 24, the valve member 18 is lifted off the valve seat 16 and establishes a hydraulic connection between the bypass line 6 and the expansion tank 1.

It is assumed in this context that the pressure in the expansion tank 1 corresponds approximately to the ambient pressure, in any case however is lower than in the annular space 5 as long as the directional control valve 8 is closed.

The opening pressure of the directional control valve 8 is determined by the pretension of the pressure spring 24 and the surface which is enclosed by the sealing edge 22.

In FIG. 2, the open directional control valve 8 is illustrated. As soon as the directional control valve 8 is opened, cooling liquid can flow from the bypass line 6 into the expansion tank 1 so that the expansion tank 1 becomes part of the cooling circuit.

In FIG. 3, the lid 2 is illustrated in the so-called service position. In the service position, the lid 2 is rotated relative to the closed position illustrated in FIG. 1 by approximately one turn, corresponding to 360 degrees or approximately 3 millimeter, out of the socket of the expansion tank 1. The service position is important when the pressure-controlled directional control valve 8 according to the invention is to be deactivated by a car mechanic in the shop in order to be able to check the function of the cooling system without having to bring the cooling system or the internal combustion engine up to operating temperature beforehand.

When the lid 2 has been brought into the service position illustrated in FIG. 3, the lower O-ring 12 in FIG. 3 lifts off the truncated cone-shaped diameter constriction 30 of the socket 1 a so that a hydraulic “short-circuiting” between the bypass line 6 and the expansion tank 1 is generated. Now the expansion tank 1 is integrated into the cooling water circuit, independent of the pressure or temperature level of the cooling water.

In FIG. 4, a cooling system with an expansion tank 1 is now schematically illustrated wherein the expansion tank 1 is provided with, or is closed off by, a lid 2 according to the invention.

An internal combustion engine carries the reference character 61. An air-water cooler carries the reference character 63. A cooling agent pump 65 circulates the water through lines (without reference characters) in the cooling circuit. A thermostat valve is provided with reference character 67. The expansion tank 1 and the corresponding lid 2 are only schematically indicated.

The bypass line 6, which connects the expansion tank 1 with the cooling water circuit when the directional control valve in the closure lid 2 is open, also has reference character 6 in FIG. 4.

Claims

1.-9. (canceled)

10. A closure lid for an expansion tank of a cooling system of an internal combustion engine, the closure lid comprising:

a housing;

a directional control valve integrated in the housing;

the directional control valve having an outlet connected to the expansion tank;

the directional control valve having an inlet connected to a bypass line;

the directional control valve adapted to open and close by pressure control or temperature control.

11. The closure lid according to claim 10, wherein the housing has a section delimiting in annular space, wherein the housing has a recess in which the directional control valve is disposed, and wherein a hydraulic connection exists between the recess and the section of the housing delimiting the annular space.

12. The closure lid according to claim 11, wherein a valve seat of the directional control valve is formed or arranged in the recess.

13. The closure lid according to claim 12, wherein the directional control valve comprises a valve member and the valve member interacts with the valve seat.

14. The closure lid according to claim 13, wherein the valve member is spring-loaded or is actuated by a bimetal.

15. The closure lid according to claim 14, further comprising a pressure spring that spring-loads the valve member, wherein the pressure spring is arranged between the valve member and a spring plate that is attached at least indirectly to the housing.

16. The closure lid according to claim 13, wherein the valve seat is a plate seat.

17. The closure lid according to claim 10, wherein a blocking function of the directional control valve depends on a screw-in depth of the closure lid in a socket of the expansion tank.

18. A cooling circuit for an internal combustion engine comprising an external cooling agent circuit and an expansion tank, wherein the external cooling agent circuit has an inlet and a return line and supplies waste heat of the internal combustion engine to a cooler of the cooling agent circuit, wherein the expansion tank is connected by a bypass line and by an outlet hydraulically to the cooling agent circuit, wherein the expansion tank has a socket and a closure lid embodied according to claim 10 and adapted to close off the socket.