GB1571335A

GB1571335A - Liquidcolled internal conbustion engine

Info

Publication number: GB1571335A
Application number: GB1437777A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1976-04-10
Filing date: 1977-04-05
Publication date: 1980-07-16
Also published as: JPS52124544A; IT1079499B; JPS5912848B2; FR2347531A1; FR2347531B1

Description

(54) LIQUID-COOLED INTERNAL COMBUSTION ENGINE (71) We, DAIMLER-BENZ AKTIEN GESELLSCHAFT, of Stuttgart-Untertiirkheim, Germany, a Company organised under the laws of the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to a liquid-cooled internal combustion engine of the kind in which the temperature of the coolant in its cooling circuit is controlled by a thermostatic mixer valve comprising a mixing chamber in open communication with the suction connection of a circulating pump in the said circuit, a return-flow chamber which is connected to a return duct from the coolant outlet of a radiator and can be shut off from the mixing chamber by a return-control valve element, and a short-circuit duct, which can be shut off from the mixing chamber by a short-circuit control valve element, which short circuit duct is connected to the coolant outlet of the engine and has an outlet connection by a forward-flow duct to the coolant inlet of the radiator.

In engines of this kind, known for instance from German Patent Specification AS 1295255, the two control valve elements are actuated by an expansible element disposed in the mixing chamber and responsive to the coolant temperature arising in that chamber. When the engine is cold, the return-control valve element is closed and the short-circuit control valve element open. Consequently, if the cooling system is filled, there will be a risk that a considerable air pocket may form in the system between the radiator and the return-control valve element and interruption of the coolant flow may occur. The present invention seeks to prevent the formation of such an air pocket at the return control valve element.

According to the invention in an engine of the kind set forth, the return-flow chamber of the mixer valve is connected by a venting connection to an auxiliary chamber which is supplied by the pump with coolant for forming a liquid seal and which has in turn a vent to a point at a high level in the coolant circuit for the purpose of promoting air separation.

With such an engine, effective venting during filling of the cooling system is provided for the system upstream of the return-control valve element. Moreover, during running of the engine, the liquid seal of the auxiliary chamber prevents the drawing in of air through the venting system, for filling, of the return flow chamber and return duct, by the pump when the return-control valve element is open. The pump could, for example, be connected to the auxiliary chamber by way of a separate supply duct for continuously replenishing the said seal.

The particular disposition of the auxiliary chamber, which might, for example, be vented into a known expansion vessel permitting volume compensation and air separation of the coolant, is not material for the invention.

In one advantageous embodiment of the engine in which the upper header of the radiator serves as air-separating chamber, a trough disposed in the said header is supplied with coolant for the seal by way of the forward-flow duct and is connected to the return-flow chamber of the mixer valve. With this arrangement, the trough is open upwardly to the air space of the header, thus dispensing with the need for a separate venting line. This applies similarly if a separate supply line is provided for the seal, whose function is thus also served by the forward-flow duct because, when the reutrn control valve element is open, the forward-flow duct automatically carries at least a proportion of the amount of coolant forced by the pump through the cooling spaces of the engine in a given time.

A separate connection for supplying the trough venting may be avoided if the trough is located below the connection to the chamber of the forward-flow duct in a protected, non-turbulent, region of the coolant flow.

It is a further object of the present invention to provide an economical design of means for venting the return-flow chamber.

This can be achieved if the auxiliary chamber is connected in series between two venting ducts of which one is connected to the said return-flow chamber and the other to the said forward-flow duct.

In this case, the forward-flow duct may assume essentially the function of removal of vented particles from the auxiliary chamber as the cooling system is filled, so that expenditure on a duct for this purpose is kept low.

In engines with a thermostatic mixer valve, it is usual for the valve to have two communicating valve connections, of which one connects the short-circuit duct to the coolant outlet of the engine and the other connects the forward-flow duct to the coolant outlet of the engine. In the application of the invention to such an engine, advantageously the mixer valve has in its body a passage which connects a venting connection from the return-flow chamber to a venting connection to the forward-flow duct. Very short duct lengths can then be obtained for the venting, for filling, of the return-flow chamber.

Examples of ways in which the invention may be put into effect will now be more fully described with reference to the accompanying drawings, in which: Figure 1 is a diagram of one form of cooling system for an internal combustion engine, Figure 2 is a partial section to a larger scale through the upper header of a radiator shown in Figure 1, Figure 3 a view similar to Figure 1, but illustrating a modified system, Figure 4 a detail view of a mixer valve to a larger scale, and Figure 5 a plan view of an annular seal shown in Figure 4.

Cooling spaces 1 and 2 of the internal combustion engine 3, through which liquid coolant, for example water, passes in succession, are connected in a coolant circuit 4 which is divided by a thermostatic mixer valve 5 into a short-circuit section 6 and a radiator section 7. The coolant inlet and outlet of the engine 3 are at 8 and 9 respectively.

A circulating pump 11 driven by the engine and connected at its delivery 10 to the inlet 8 is in open communication by way of suction pipe 12 with the mixing chamber 13 of the valve 5. The valve 5 has two inter-communicating connections, namely a connection 14 to the outlet 9 and a connection 15 to a forward-flow pipe 18, leading to the upper header 16 of a radiator 17, respectively. A short-circuit passage 19 in the valve 5 is connected to the outlet 9 by the connection 14 and by way of a short-circuit control valve element 20 to the chamber 13. A return-flow chamber 23 of the valve 5 is connected through a returnflow pipe 21 to the lower head 22 of the radiator 17 and by way of return-flow control valve element 24 to the chamber 13.

The valve elements 20 and 24 are actuated by an expansible cylinder element 25 filled with a temperature-responsive expansible material and disposed in the mixing chamber. The piston rod 26 of the cylinder is fixed in the valve 5. The valve elements 20 and 24 are operated in per se known manner: When the coolant is hot, the valve element 24 is open and the valve element 20 closed, giving maximum flow through the radiator. When the coolant is cold, the element 24 is closed and the element 20 open, giving a maximum by-pass flow. At an intermediate coolant temperature, the valve elements may be in intermediate positions, so that coolant from the engine is divided between the radiator and by pass.

In the example of Figure 1, the body of the valve 5 has a venting duct 27 which opens at one end into the return-flow chamber 23 and at the other end into a venting line 28. The line extends to an auxiliary chamber, in the form of a trough 29 open at the top 32, in the upper header 16 below the opening 30 (Figure 2) of the connection 31 for the forward-flow pipe 18 leading into that header. The open top 32, which affords a vent to a point at a high level in the coolant circuit, is located in a region protected from turbulent coolant flow from the opening 30. Thus the trough 29 will always contain a reverse of liquid, supplied by way of the pipe 18 from the pump 11, which will prevent air from being drawn out of the header 16 via 28-23-12 by the pump when the valve element 24 is open.

When the cooling system is filled, the trough 29 will be empty, so the return-flow pipe 21 and chamber 23 will be vented to atmosphere by way of the line 28 and the filler 33, opened by removal of the cap, on the header 16.

The system illustrated in Figure 3 differs from that of Figure 1 in the following respects: The body of the mixer valve 5 has a passage 29' connected to the duct 27 for venting the return-flow chamber 23. The passage 29' acts as auxiliary chamber for a liquid reserve and communicates via a vent 32', to a point at a high level in the coolant circuit, with the connection 15 to the forward-flow pipe 18.

When the system is being filled by way of the opened filler 33, the return-flow control valve element 24 will be closed.

Any air enclosed in the pipe 21 and chamber 23 will escape by way of 27-29'-32'-1518-33 to the atmosphere. When the engine is running, drops or bubbles of water will constantly pass from the connection 15 to the pipe 18 by way of the vent 32' into the passage 29' in the valve body, where they collect and act after the fashion of a liquid seal and prevent the drawing in of air from the upper header 16 by the pump 11, in the event of a slight fall in the level of liquid in the radiator 17 and, therefore, also in the pipe 18, which might otherwise result in interruption of the coolant flow due to an air bubble.

The mixer valve 5 comprises a body 34 (Figure 4) with a separating surface 35 on which is mounted a cover 36 with a corresponding surface 37. The rim 38 of a valveseating disc 39 is clamped between the body and cover. Supported on the valve seating disc 39 in known manner are coaxial valve heads 40 and 41 of the short-circuit and return-flow control valve elements 20 and 24 respectively. The passage 29' in the body comprises a section 43 extending parallel to the common axis 42 of the heads 40 and 41 and passing through the surfaces 35 and 37. The rim 38 is enclosed by an annular seal 44 which, at the position of - the passage 29', has a tongue-shaped lug 45 (Figure 5) with a cylindrical through hole 46 which is installed in alignment with the passage section 43. To determine this position, the seal 44 is provided with three locating projections 47.

WHAT WE CLAIM IS: - 1. A liquid-cooled internal combustion engine of the kind set forth, wherein the return-flow chamber of the mixer valve is connected by a venting connection to an auxiliary chamber which is supplied by the pump with coolant for forming a liquid seal and which has in turn a vent to a point at a high level in the coolant circuit for the purpose of promoting air separation.

2. An engine according to claim 1, wherein the upper header of the radiator serves as air-separating chamber and a trough disposed in the said header is supplied with coolant for the seal by way of the forward-flow duct and is connected to the return-flow chamber of the mixer valve.

3. An engine according to claim 1 or 2, wherein the auxiliary chamber or trough is situated, at a lower level than the connection to the radiator of the forward-flow duct, in a 7protected region of coolant flow.

4. An engine according to claim 1, wherein the auxiliary chamber is connected in series between two venting ducts of which one is connected to the said returnflow chamber and the other to the said forward-flow duct.

5. An engine according to claim 4, wherein the mixer valve has two communicating valve connections, of which one connects the said short-circuit duct to the coolant outlet of the engine and the other connects the said forward-flow duct to the said oultet, the said valve having in its body a passage which connects a venting connection from the return-flow chamber to a venting connection to the forwardflow duct.

6. An engine according to claim 5, wherein valve heads of the short-circuit control valve element and return-flow control valve element are supported on a valveseating disc whose rim is clamped between corresponding separating surfaces of the valve body and a cover therefor, the said passage comprising a section extending close to the said rim and passing through the said surfaces.

7. An engine according to claim 6, wherein the said rim co-operates with an annular seal having a radial, tongueshaped, lug with a through hole in alignment with the said section of passage.

8. An internal combustion engine substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

9. An internal combustion engine substantially as hereinbefore described with reference to Figures 3 to 5 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. passage 29' connected to the duct 27 for venting the return-flow chamber 23. The passage 29' acts as auxiliary chamber for a liquid reserve and communicates via a vent 32', to a point at a high level in the coolant circuit, with the connection 15 to the forward-flow pipe 18. When the system is being filled by way of the opened filler 33, the return-flow control valve element 24 will be closed. Any air enclosed in the pipe 21 and chamber 23 will escape by way of 27-29'-32'-1518-33 to the atmosphere. When the engine is running, drops or bubbles of water will constantly pass from the connection 15 to the pipe 18 by way of the vent 32' into the passage 29' in the valve body, where they collect and act after the fashion of a liquid seal and prevent the drawing in of air from the upper header 16 by the pump 11, in the event of a slight fall in the level of liquid in the radiator 17 and, therefore, also in the pipe 18, which might otherwise result in interruption of the coolant flow due to an air bubble. The mixer valve 5 comprises a body 34 (Figure 4) with a separating surface 35 on which is mounted a cover 36 with a corresponding surface 37. The rim 38 of a valveseating disc 39 is clamped between the body and cover. Supported on the valve seating disc 39 in known manner are coaxial valve heads 40 and 41 of the short-circuit and return-flow control valve elements 20 and 24 respectively. The passage 29' in the body comprises a section 43 extending parallel to the common axis 42 of the heads 40 and 41 and passing through the surfaces 35 and 37. The rim 38 is enclosed by an annular seal 44 which, at the position of - the passage 29', has a tongue-shaped lug 45 (Figure 5) with a cylindrical through hole 46 which is installed in alignment with the passage section 43. To determine this position, the seal 44 is provided with three locating projections 47. WHAT WE CLAIM IS: -

1. A liquid-cooled internal combustion engine of the kind set forth, wherein the return-flow chamber of the mixer valve is connected by a venting connection to an auxiliary chamber which is supplied by the pump with coolant for forming a liquid seal and which has in turn a vent to a point at a high level in the coolant circuit for the purpose of promoting air separation.