THERMOSTAT VALVE AND METHOD FOR OPERATING A THERMOSTAT VALVE

Abstract

A thermostat valve for an internal combustion engine includes a housing with several cooling liquid connections and a drive which drives in rotation a hollow valve element mounted rotationally in the housing, by exerting a drive force, wherein the valve element has several openings delimited by its circumferential face which can be brought selectively in congruence with one or more of the cooling liquid connections of the housing by rotation of the valve element for the throughflow of cooling liquid.

Claims

1. A thermostat valve for an internal combustion engine, comprising a housing with a plurality of cooling liquid connections and a drive which drives a hollow valve element which is mounted rotatably in the housing, rotationally by way of the exertion of a drive force, the valve element having a plurality of openings which are delimited by its circumferential face and can be brought into congruence selectively with one or more of the cooling liquid connections of the housing for the throughflow of cooling liquid by way of rotation of the valve element, wherein adjacently with respect to one of the openings, the circumferential face of the valve element has a depression or a cutout, the valve element can assume a connecting position, a closed position and an intermediate position between the connecting position and the closed position, the relevant opening being in congruence with one of the cooling liquid connections of the housing in the connecting position and a cooling liquid flow being possible between the interior of the valve element and the relevant cooling liquid connection, the relevant opening not being in congruence with the relevant cooling liquid connection of the housing in the closed position and a cooling liquid flow not being possible between the interior of the valve element and the relevant cooling liquid connection, and the relevant opening likewise not being in congruence with the relevant cooling liquid connection of the housing in the intermediate position, a cooling liquid flow being possible between the interior of the valve element and the relevant cooling liquid connection, however, through the depression or the cutout, the intermediate position is defined by a stop element which is prestressed into a blocked position and against which the valve element moves with an actuating section in the case of a drive force which does not exceed a limit force, the stop element being moved counter to its prestress by the actuating section of the valve element by way of the exertion of a drive force which exceeds the limit force, into a released position, in which the valve element can be moved with its actuating section past the stop element in order to leave the intermediate position.

2. The thermostat valve as claimed in claim 1, wherein the movement of the stop element counter to its prestress into the released position is effected by the actuating section of the valve element by way of the exertion of the drive force which exceeds the limit force during a rotation of the valve element out of the intermediate position into the closed position.

3. The thermostat valve as claimed in claim 1, wherein the connecting position and the closed position of the valve element are defined in each case by way of an end stop.

4. The thermostat valve as claimed in claim 1, wherein the stop element is spring-prestressed into the blocked position.

5. The thermostat valve as claimed in claim 4, wherein the stop element is an elastic spring arm which is clamped in fixedly with its one end, the actuating section moving in the blocked position against that free end of the spring arm which lies opposite the end which is clamped in fixedly.

6. The thermostat valve as claimed in claim 5, wherein the spring arm has, at its free end, a bent section, preferably a section which is bent in a V-shape, against which the actuating section moves.

7. The thermostat valve as claimed in claim 1, wherein the actuating section is an actuating projection which is formed on the outer side of the valve element.

8. The thermostat valve as claimed in claim 7, wherein the actuating section is formed at one end of a shaft which mounts the valve element rotationally.

9. The thermostat valve as claimed in claim 1, wherein the valve element is prestressed into the connecting position by way of spring prestress, with the result that the valve element assumes the connecting position if the drive fails.

10. The thermostat valve as claimed in claim 1, wherein the drive is a linear drive which acts eccentrically on a shaft which mounts the valve element rotationally.

11. The thermostat valve as claimed in claim 1, wherein the drive is a vacuum drive or an electric drive.

12. The thermostat valve as claimed in claim 1, wherein at least one of the cooling liquid connections has sealing means which comprise at least one sliding ring which is adapted to the circumferential face of the valve element and at least one elastic sealing ring which prestresses the sliding ring against the circumferential face of the valve element.

13. A method for operating a thermostat valve as claimed in claim 1, comprising the steps of: rotating of the valve element out of the connecting position into the closed position by way of a drive force which exceeds the limit force, the valve element being moved with its actuating section past the stop element with movement of the stop element counter to its prestress into its released position, subsequent rotating of the valve element back out of the closed position beyond the intermediate position as far as into a position, in which the relevant opening of the valve element is in partial congruence with the relevant cooling liquid connection of the housing and a cooling liquid flow is possible between the interior of the valve element and the relevant cooling liquid connection, subsequent rotating of the valve element back into the intermediate position by way of a drive force which does not exceed the limit force, with the result that a cooling liquid flow takes place between the interior of the valve element and the relevant cooling liquid connection through the depression or the cutout.

14. The method as claimed in claim 13, wherein the valve element is subsequently rotated back out of the intermediate position into the connecting position.

Description

[0027] An embodiment of the invention will now be explained in further detail below with reference to the drawings. These show diagrammatically:

[0028] FIG. 1 a thermostat valve according to the invention in a perspective view;

[0029] FIG. 2 the thermostat valve of FIG. 1 in a sectional view;

[0030] FIG. 3 a part of the thermostat valve shown in FIG. 1 in a first operating position in a perspective view;

[0031] FIG. 4 a cross-sectional view through the thermostat valve in the operating position shown in FIG. 3;

[0032] FIG. 5 a part of the thermostat valve shown in FIG. 1 in a second operating position in a perspective view;

[0033] FIG. 6 a cross-sectional view through the thermostat valve according to the invention in the operating position illustrated in FIG. 5;

[0034] FIG. 7 a part of the thermostat valve illustrated in FIG. 1 in a third operating position in a perspective view;

[0035] FIG. 8 a cross-sectional view through the thermostat valve according to the invention in the operating position illustrated in FIG. 7;

[0036] FIG. 9 a part of the thermostat valve illustrated in FIG. 1 in a fourth operating position in a perspective view;

[0037] FIG. 10 a cross-sectional view through the thermostat valve according to the invention in the operating position illustrated in FIG. 9, and

[0038] FIG. 11 a flow chart for illustrating the mode of operation of the drive of the thermostat valve according to the invention.

[0039] Unless stated otherwise, the same reference numerals in the figures designate the same objects. The thermostat valve according to the invention illustrated in FIGS. 1 and 2 serves for the temperature regulation of an internal combustion engine (not shown) of an automobile. The thermostat valve has a housing 10 with a first cooling liquid connection 12 and a second cooling liquid connection 14. The first cooling liquid connection 12 is connected in operation by way of example to cooling channels which run through the internal combustion engine and the second cooling liquid connection 14 is connected during operation by way of example to a radiator. A hollow spherical segment shaped valve element 16 which is designed as a half shell and is shown in FIGS. 3 to 10 is rotationally mounted in the housing 10 by way of a shaft 18. A drive which is here formed as a vacuum drive 22 engages via a drive rod 24 on the shaft 18 eccentrically by way of an eccentric section 20. The drive rod 24 has at its end an articulation section 26 which is mounted for articulation on a bearing pin 28 of the eccentric section 20. A translation movement of the drive rod 24 can be converted by this coupling into a rotational movement of the shaft 18 and thus of the valve element 16 in the housing 10. The vacuum drive 22 generates an adjustable low pressure, such as will be explained in further detail below, through which the drive rod 24 is drawn into the housing of the vacuum drive 22 against the prestress of a resetting spring 30 shown in FIG. 2 and with compression of the resetting spring 30. If the low pressure drops sharply or the vacuum drive fails then the resetting spring 30 presses the drive rod 24 out from the housing of the vacuum drive 22 into the connecting position which is shown in FIGS. 1 and 2 and which will be explained in further detail below.

[0040] An elastic spring arm 36 which can be made by way of example of spring steel is fixedly clamped by its one end in a clamp 34 on a holding plate 32 which is formed on the housing 10 of the thermostat valve. The spring arm 36 forms a stop element. The opposite end of the spring arm 36 is free and is bent in a V-shape in cross-section. The position illustrated in FIGS. 1 and 2 is the blocked position of the spring arm 36. An actuating section which is formed as an actuating projection 38 is moulded on the shaft 18. The actuating projection 38 interacts with the spring arm 36 in the manner which will be explained in further detail below.

[0041] Different operating positions of the thermostat valve according to the invention are to be explained using FIGS. 3 to 10. FIGS. 3 and 4 show the connecting position illustrated in FIGS. 1 and 2 and which at the same time is the fail-safe position adopted in the event of a failure of the vacuum drive 22. In this position the drive arm 24 is located in its widest extended position. It can be seen in FIGS. 3 and 4 that the spherical segment shaped valve element 16 has a first opening 40 delimited by its circumferential face and a larger second opening 42 likewise delimited by its circumferential face. The second opening 42 is formed by the open region of the half shell. It should be pointed out that in FIGS. 3, 5, 7 and 9 for reasons of clarity the housing 10 of the thermostat valve including the clamping of the spring arm 36 is not shown. However sealing means of the first cooling liquid connection 12 can be seen in FIGS. 3 to 10, and here comprise a sliding ring 44 adapted to the circumferential face of the valve element 16, as well as an elastic sealing ring 46 which prestresses the sliding ring 44 against the circumferential face of the valve element 16. As can be seen in particular in the sectional illustration in FIG. 4, in the connecting position adopted in FIGS. 3 and 4 the opening 40 of the valve element 26 is in complete congruence with the first cooling liquid connection 12. In this connecting position a maximum cooling liquid throughflow between the cooling liquid connections 14, 12 is possible through the valve element 16. It can furthermore be seen that the circumferential face of the valve element 16 adjoining the smaller opening 40 has a channel-like or trench-like depression 48.

[0042] By applying a high vacuum through the vacuum drive 22 and a drive force by the drive rod 24 which is caused thereby and exceeds a predetermined limit force, the eccentric section 20 can be drawn from the connecting position illustrated in FIGS. 3 and 4 into the closing position of the valve element 16 shown in FIGS. 5 and 6. This drive force must be recognisably large enough so that the actuating projection 38 can press the spring arm 36 against its spring prestress from the blocked position into the free position illustrated in FIG. 5 in which the actuating projection 38 can pass by the spring arm 36, more particularly the V-shaped bent free end of the spring arm 36. In this position of the valve element 16 the first cooling liquid connection 12 of the housing 10 is closed completely by the circumferential face of the valve element 16, as can be seen in particular in FIG. 6. In this closed position of the valve element 16 no cooling liquid throughflow is possible between the cooling liquid connections 14, 12 of the housing 10.

[0043] Through a reduction of the applied vacuum of the vacuum drive 22 the drive rod 24 is forced out again from the housing of the vacuum drive 22 by the resetting spring 30 whereby the valve element 16 is rotated by way of the eccentric section 20 into the position illustrated in FIGS. 7 and 8 in which a partial, by way of example roughly half, congruence exists between the smaller opening 40 of the valve element 16 and the first cooling liquid connection 12 of the housing 10. In this position a cooling liquid throughflow between the cooling liquid connections 14, 12 of the housing 10 can thus take place, as can be seen in particular in FIG. 8.

[0044] Through renewed application of a vacuum through the vacuum drive 22 which leads to a drive force which is exerted by the drive rod 24 during the course of the retraction into the housing of the vacuum drive 22 and is below the predetermined limit force, the valve element 16 is then rotated into the intermediate position illustrated in FIGS. 9 and 10. The intermediate position is clearly defined by the actuating projection 38 stopping against the free end of the spring arm 36, as shown in FIG. 9. The drive force thereby exerted which is below the limit force is not sufficient to prestress the spring arm 36 through the actuating projection 38 out from the blocked position into the release position. As can be seen in FIG. 10, in this intermediate position no congruence is provided between the smaller opening 40 of the valve element 16 and the first cooling liquid connection 12. Nevertheless in this intermediate position of the valve element 16 a small cooling liquid throughflow between the cooling liquid connections 14, 12 of the housing 10 is possible, namely through the depression 48 which adjoins the opening 40. In this intermediate position a small cooling liquid throughflow is guaranteed which is sufficient to avoid undesired hotspots in the internal combustion engine and in order to reliably determine the temperature of the internal combustion engine by way of the temperature of the cooling liquid.

[0045] The flow chart in FIG. 11 diagrammatically illustrates the path of the vacuum applied by the vacuum drive 22, and the positions of the valve element reached hereby. With the so-called “0-vacuum”, an ambient pressure (about 100 kPa) exists, the valve element is located in the connecting position. If a rising low pressure is applied then the drive rod 24 is drawn into the housing of the vacuum drive 22, as shown in FIG. 11 by the traction direction, until reaching the intermediate position. This can be achieved by way of example with an absolute pressure of about 65 kPa (“¾-vacuum”). Up to this vacuum the drive force is not sufficient to press the spring arm 36 through the actuating projection 38 into the released position. If a still higher vacuum is applied the prestress of the spring arm 36 is on the other hand overcome and the valve element 16 can be rotated into the closed position.