GB2387647A

GB2387647A - Engine cooling system with tangentially ported thermostsatic valve assembly

Info

Publication number: GB2387647A
Application number: GB0304776A
Authority: GB
Inventors: William Richard Hutchins
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2002-03-07
Filing date: 2003-03-03
Publication date: 2003-10-22
Anticipated expiration: 2023-03-03
Also published as: GB0304776D0; GB2387647B; GB0205380D0

Abstract

An engine cooling system has a thermostatic valve assembly and includes a radiator arranged with a bypass flow. The thermostatic valve operates to distribute a portion of the engine coolant flow through the radiator and the bypass. The thermostatic valve has a housing defining a cylindrical valve chamber (19 fig 5), a radiator port within a radiator return tube 14 to connect the valve chamber to the radiator, a bypass port within a bypass entry tube 16 to connect the valve chamber to the bypass duct and an engine port 18A within an engine return tube 18 to connect the valve chamber to the engine. At least one of the radiator port and the engine port is arranged tangentially to the valve chamber such that its axis is offset from the axis of the valve chamber. The tangential port induces swirl in the valve chamber from the moving flow stream. Both the engine port and radiator port may be arranged tangential to the valve chamber, and the engine port may be inclined with respect to an axis which is parallel to the valve chamber. At least one of the engine or radiator ports may be blended into the inner wall of the valve chamber.

Description

- 1 Thermostatic Valve Assembly for use in an Enaine Cooling System This

invention relates to thermostatic valve assemblies for use in the cooling systems of internal combustion engines, particularly but not exclusively for use in engine cooling systems of motor vehicles.

Such thermostatic valve assemblies can produce considerable flow restrictions 5 when the flow of coolant is at or near a maximum. This is primarily due to sudden changes in the size of the coolant flow passages as they join the main valve chamber of the valve assembly and to changes in the direction of flow of the coolant entering and leaving the valve assembly.

It is an object of this invention to provide an improved thermostatic valve 10 assembly which alleviates the above disadvantage.

According to a first aspect of the invention there is provided a thermostatic valve assembly for use in an engine cooling system which includes a radiator through which a proportion of the flow of coolant through the engine can be passed as a radiator flow and a bypass duct through which another proportion of the flown through the engine can 15 be passed as a bypass flow without passing through the radiator, the thermostatic valve assembly being operative to distribute the proportions of the radiator flow and the bypass flow and comprising a housing defining a cylindrical valve chamber, a radiator port to connect the valve chamber to the radiator, a bypass port to connect the valve chamber to the bypass duct and an engine port to connect the valve chamber to the 20 engine, wherein at least one of the radiator port and the engine port is arranged tangentially to the valve chamber such that its axis is offset substantially from the axis of the valve chamber and flow through said at least one port to induces swirl in the valve chamber.

c -2 In a preferred arrangement, the thermostatic valve assembly is arranged to control the flow of cold coolant from the radiator (a socalled bottom hose position) so that the engine port is an engine return port for the return of coolant to the engine, the radiator port is a radiator return port for the flow of coolant from the radiator and the 5 bypass port is for coolant flowing from the bypass duct. However, the thermostatic valve assembly may also be arranged to control the flow of hot coolant into the radiator (a so-called top hose position) so that the engine port is an engine outlet port for the flow of coolant from the engine, the radiator port is a radiator delivery port for the flow of coolant to the radiator and the bypass port is for coolant flowing into the bypass 1 0 duct.

In a preferred embodiment, the engine port and the radiator port are both arranged tangentially to the valve chamber. However, installation constraints may prevent this arrangement and only one of these ports may be arranged in this way.

Conveniently, the engine port is aligned at an angle inclined to a line lying parallel 15 to the axis of the valve chamber.

Said at least one of the engine port and the radiator port may be arranged so that a substantial portion of the inner wall of the port is blended into the adjacent inner wall of the valve chamber.

The invention also provides, according to a second aspect thereof, an engine 20 cooling system comprising a radiator through which a proportion of the flow of coolant through the engine can be passed as a radiator flow, a bypass duct through which another proportion of the flow through the engine can flow without passing rough the radiator and a thermostatic valve assembly according to said first aspect.

-3 The invention will now be described by way of example and with reference to the accompanying drawings, of which: Fig.1 is a diagrammatic representation of a cooling system of an internal combustion engine of a motor vehicle and incorporating the invention; 5 Fig.2 is a plan view of a thermostatic valve assembly according to the invention for use in the cooling system shown in Fig.1; Fig.3 is a side view of the assembly shown in Fig.2; Fig.4 is an end view in the direction of arrow V in Fig. 2; Fig. 5 is a scrap cross-section through the valve assembly shown in Fig.2 on the 10 axis Y-Y; and Fig. 6 is a geometric line drawing showing the alignment of an engine return port of the valve assembly shown in Fig.2.

The engine cooling system illustrated in Fig.1 comprises an airooled radiator R connected to an engine E by a top hose TH. A thermostatic valve assembly 10 is 15 positioned between a bottom hose BH leading from the radiator R and the return line RL to control the flow of coolant through the radiator R and a bypass duct B. An engine-driven pump P in a return line RL returns coolant to the engine E and hence circulates the coolant around the cooling system. A heater matrix H through which air for the interior of the vehicle can be driven by a fan F takes a supply of hot coolant 20 from the top hose TH and returns it to the return line RL downstream of the thermostatic valve assembly 10.

With particular reference to Figs.2 to 6 the thermostatic valve assembly 10 comprises a housing 12 defining a cylindrical valve chamber 19 having a longitudinal axis X-X, a radiator return tube 14 defining radiator return port for connection to the 25 bottom hose BH from the radiator R. a bypass entry tube 16 defining a bypass port for connection to the bypass duct B and an engine return tube 18 defining an engine return port 1 8A forconnection to the return line RL.

A thermostat valve (not shown, but typically being as shown and described in EP-A-0794327) is mounted within the chamber 19 to control the flow of coolant entering via the return and bypass tubes 14 and 16. The thermostat valve includes a main valve member which, when the cooling system is cold (i.e. at ambient 5 temperature), abuts an annular seat to close off the radiator return port. In response to an increasing temperature in the bypass flow from the bypass duct, the main valve member becomes unseated to define an annular flow channel between the main valve member and the annular seat. A bypass valve member is provided to regulate the flow through the bypass entry tube 16. Thus a proportion of the flow of coolant through the 10 engine can be passed as a radiator flow and another proportion of the flow through the engine can flow through the bypass duct without passing through the radiator, the thermostatic valve assembly being operative to distribute the proportions- of the radiator flow and the bypass flow The engine return tube 18 has a bore of diameter d1 forming the engine return 15 port 18A. As shown particularly in Figs.5 and 6, the longitudinal axis Y-Y of the engine return tube 18 (and thus the engine return port 1 8A) is arranged at a tangent to a circle "Q" centred about the longitudinal axis X-X of the valve chamber 19 and is thus offset substantially from the axis X-X. The longitudinal axis Y-Y of the engine return port 1 8A is also inclined at an angle O with respect to a line Z-Z parallel to the axis X-X. The line 20 Z-Z intersects the axis Y-Y at a point P where the axis Y-Y meets the circle Q at a tangent. The engine return port 1 8A is arranged so that the portion of the inner wall of the port which is furthest offset from the valve chamber axis X-X is almost tangential to the adjacent inner wall of the valve chamber 19 and, as can be seen at 19B, blends into the valve chamber inner wall.

25 The arrangement of the engine return port 18A at a tangent to the chamber 18 has two effects. Firstly, it encourages a circulation or vortex flow within the chamber 19 about the longitudinal axis X-X, as indicated by the arrows "C" in Fig.6, the direction

-5 - of flow "O" in the engine return port 18A being generally uniform and tangential to the flow of coolant circulating in the chamber 19. Secondly, the tangential arrangement increases the cross-sectional area of the engine return port at its intersection with the chamber 19. This can be seen in Fig.6 where the maximum dimension d2 formed at 5 the generally elliptical intersection of the outlet tube 18 with the chamber 19 is greater than the diameter d1 of the engine return port. In addition, because the engine return port 18A is arranged tangentially with respect to the valve chamber 19, there is less loss of momentum as the coolant leaves the chamber 19 and enters the outlet tube 18 resulting in a lower pressure drop. This is particularly beneficial at high engine speeds.

10 The radiator return tube 14 is in the form of an elbow so that the radiator return port defined by the radiator return tube 14 is also arranged so that is main axis A-A is tangential and offset substantially from the axis X-X of the valve chamber 19. Thus flow through the radiator return port also produces a vortex flow around the longitudinal axis X-X within the chamber 19 upstream of the main valve member when the main 15 valve member is unseated. This has the advantage that the coolant flow entering the - chamber 19 does not impinge at right angles upon the annular flow channel formed between the main valve member and the adjacent valve seat but at an angle.

Therefore, when the main valve member is open, coolant flowing through the radiator return port undergoes far less change in direction than if this port is aligned with the 20 axis X-X of the valve chamber 19. Hence the pressure drop across the main valve member can be reduced.

The helical vortex flow induced by the tangential alignment of the radiator return tube 14 enhances the vortex flow produced by the tangential arrangement of the engine return tube 18. It will however be appreciated that if only one of the radiator 25 return tube 14 and the outlet 18 is tangentially arranged a vortex flow will still be created and a reduction in pressure loss achieved. However, the combination of a

-6 tangentially arranged inlet and outlet strengthens the vortex flow produced and maximises the reduction in pressure loss.

In a modification (not shown), the axis Y-Y of the engine return port 18A is further offset from the valve chamber axis X-X than is shown in Fig.5. This creates a 5 downward step for the flow of coolant exiting the valve chamber at the engine return port 18A which step can be blended as previously described. The effect is to reduce the angle at the junction between the wall of the engine return port 18A and the adjacent wall portion of the valve chamber 19 at the point (19C in Fig.5) least offset from the valve chamber axis X-X so that the vortex flow in the valve chamber 19 is 10 more readily divided between the flow exiting at the engine return port 18A and the flow which recirculates around the valve chamber in the directions of the arrows "C".

Claims

1. A thermostatic valve assembly for use in an engine cooling system which includes a radiator through which a proportion of the flow of coolant through the engine can be passed as a radiator flow and a bypass duct through which another proportion of the flow through the engine can be passed as a bypass flow without passing through the radiator, the thermostatic valve assembly being operative to distribute the proportions of the radiator flow and the bypass flow and comprising a housing defining a cylindrical valve chamber, a radiator port to connect the valve chamber to the radiator, a bypass port to connect the valve chamber to the bypass duct and an engine port to connect the valve chamber to the engine, wherein at least one of the radiator port and the engine port is arranged tangentially to the valve chamber such that its axis is offset substantially from the axis of the valve chamber and flow through said at least one port to induces swirl in the valve chamber.

2. An assembly as claimed in claim 1 in which the engine port and the radiator port are both arranged tangentially to the valve chamber.

3. An assembly as claimed in Claim 1 or in Claim 2 in which the engine port is

aligned at an angle inclined to a line lying parallel to the axis of the valve chamber.

4. An assembly as claimed in any preceding claim wherein said at least one of the engine port and the radiator port is arranged so that a substantial portion of the inner wall of the port is blended into the adjacent inner wall of the valve chamber.

5. An engine cooling system comprising a radiator through which a proportion of the flow of coolant through the engine can be passed as a radiator flow and a bypass duct through which another proportion of the flow through the engine can flow

-8 - without passing through the radiator and including a thermostatic valve assembly as claimed in any preceding claim.

6. A thermostatic valve assembly substantially as described herein with reference to the accompanying drawings.

7. An engine cooling system substantially as described herein with reference to the accompanying drawings.