GB2245956A

GB2245956A - A thermostat assembly for a cooling circuit of an internal combustion engine

Info

Publication number: GB2245956A
Application number: GB9015402A
Authority: GB
Inventors: Frederick George Eysenck; Richard Huish Spray
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1990-07-13
Filing date: 1990-07-13
Publication date: 1992-01-15
Also published as: GB9015402D0

Abstract

A thermostat assembly 14 for a cooling circuit of an internal combustion engine comprises two housing pans 20, 21 which are snap-locked together to define a chamber 34 in which is located a thermostat 19. The thermostat 19 has a circumferential flange 24 upon which is attached sealing material 23 used to provide a seal between the first and second housing pans 20 and 21, which are preferably made from a reinforced polyamide material. <IMAGE>

Description

A THERMOSTAT ASSEMBLY FOR A COOLING CIRCUIT OF AN INTERNAL COMBUSTION ENGINE Tnis invention relates to a tnermostat assemoly tor a cooling circuit of an internal combustion engine.

It is well known to provide a thermostat assembly for tne cooling circuit of an internal combustion engine to restrict the flow of cooling water tnrougn tne engine when tne engine is started from cold.

It is usual to provide a recess in tne cylinder block or cylinder nead into wnicn tne thermostat is fitted and a separate cover connected to the cylinder Blocs or cylinder head by means of several threaded fasteners to define In combination witn sain recess a tnermostat chamber.

It is a disadvantage witn sucn Known tnermostat assemblies tflat it is time consuming during manufacture ot tne engine to connect tne separate cover to the cylinder Dock our cylinder head.

It is an object or tnis invention to overcome tne disadvantage associated with known tnermostat assemblies.

According to a first aspect of tne invention there is provided a thermostat assemoly for a cooling circuit of an internal combustion engine comprising a first resilient part, a second resilient part and a thermostat mounted within a chamber defined by said first and second parts.

The first resilient part and or tne second resilient part may be made from a synthetic plastic material such as polyamide.

The first resilient part may define a bore for cooperation with tne second part, the chamber in which is located said thermostat and at least one conduit for connection of said chamber to the cooling circuit of the engine with which tne assembly is associated in use.

Snap-locK connection means may be provided within said oore and on said second part to provide a connection Detween said tirst and second parts upon insertion of the second part into the bore ot the tirst part.

Preferably, the thermostat may have a circumferential flange by which it is located and secured in the bore ot the first resilient part.

Advantageously, the side faces of the circumferential flange may have a resilient sealing material attached thereto.

Preferably, the resilient sealing material provides a seal between the thirst and second parts and may additionally bias tne flange of tne second part against one face of the circumferential groove.

Tne resilient sealing material may be compressed between an annular race in the bore of the first resilient part and an end face of tne second part.

according to a second aspect of tne invention tnere is providea a cooling circuit tor an internal combustion engine including a tnermostat assemoly according to the first aspect of tne invention.

Preferably, tne tnermostat assemoly is connected. into tne cooling circuit by means of two pUSh fit couplings.

Tne invention will now be described witn reference to tne accompanying drawings ot whicn: Figure 1: is a sci:iematic drawing of a cooling circuit for an internal combustion engine according to a second aspect of tne invention; Figure 2: is a cross section trough a tnermostat assemoly according to a first aspect of the invention; Figure 3: is an enlarged view of the area indicated oy A on Figure 2.

Witn reference to Figure 1 there is shown an engine 11 having a coolant circulation pump 12, a radiator 13 naving a top tank 16 and a Dottom tank 17, a thermostat assemoly 14 interposed Detween the oottom tank 17 and tne coolant circulation pump 12 and a neater unit 15 interposed between a return conduit 10 from the engine to tne top tank 16 and a bypass passage 22 through the thermostat assembly 14.

In operation tne cooling circuit operates as follows, initially, wnen tne engine is cold, tne thermostat assemoly 14 is in a closed position preventing the passage ot coolant from tne bottom tanK 17 into tne engine 11 via tne circulation pump 12. However, to prevent local overneating or tne engine 11 an initial flow of coolant tnrougn tne engine 11 is allowea througn tne bypass passage 22 and neater 15.

Wnen tne temperature of tne coolant passing tnrougn tne thermostat assemoly 14 reaches a predetermined temperature the thermostat asseinsly 14 is operative to allow coolant to gradually be admitted from the bottom tank 17 tnrough the supply tube 18.

When the engine is at its normal running temperature, coolant passes freely from tne bottom tanK 17 througn tne thermostat assembly 14 and into the circulation pump 12 and tnence tnrough the cooling passages (not snown) defined witnin tne engine 11 and back to the top tanx 16 via tne return tube 10 to be cooled for recirculation from tne cotton tank 17.

With particular reference to Figures 2 and 3 tnere is snown a thermostat assemoly 14 comprising a resilient first part 2, a second resilient part 21 snap locked to tne first part 20 and a thermostat 19 mounted within said first and second parts 20 and 21.

The first resilient part 20 is made from a reinforced polyamide material and defines a oore 33 leading to a cnamoer 34, a bypass conduit 22 leading to tne chamber 34 and an outlet conduit 35 leading away from tne cnamoer 34.

Tne bore 33 has a circumferential groove 27 formed tnerein and terminates in an annular face 29 at its juncture witn the cnamoer 34.

The groove 27 has an annular retaining surface 28 faclng towards tne annular face 29.

The outlet conduit 35 has an 'O' ring seal 40 fitted in a groove 41 to provide a push fit connection means used to connect the outlet conduit 35 to tne inlet of tne circulation pump 12.

The second resilient part 21 is made from a tiore reinforcea polyamide material and is essentially tubular having a circumferential flange 26 at one end for insertion into tne first part 20 and an 'O' ring seal 43 fitted in a groove 44 to provide a pusn fit connection means used to connect tne second part 21 to the supply tube 18.

The flange 2t has a front face 31 and a rear race 32 tne front face having a chamfer 3U around its outer peripnery to assist engagement of tne flange 26 witn the oore 33.

Tne thermostat 19 nas a circumferential flange 24 usea to mount tne tnermostat 19 witn the oore 33.

Elastomeric sealing material 2J attacned to sldes Laces or the flange 26 to provide a seal between the first and second parts 20 and 21.

The first and second parts 20 and 21 are neld together by a snap-locK coupling formed by the groove 27 in the bore 33 and tne flange 26 on the second part 21.

When the first and second parts 20 and 21 are in tneir pre-assembled state the outside diameter of the flange 26 on the second part 21 is greater tnan the oore 33 in the first part 20 into which it is to be fitted.

Upon assembly of the the first and second parts 20 and 21 tne first and second parts 20, 21 are elastically deformea by tne insertion of tne flange 26 into the oore 33.

As the second part 21 is engaged with the first part 20 tne sealing material 23 is compressed between the front face 31 of tne tlange 26 and tne annular face 29 thereby forming a seal oetween the first and second parts 2O, 21.

Upon tull engagement of the flange 26 witn tne groove 27 tne first and second parts 20 and 21 undergo partial elastic recovery and tne oore 33 returns to a diameter smaller tnan tnat or tne flange 26 tnereoy locking tne first and second parts ZU and 21 togetner.

Tne compression of tne sealing material 23 oy the insertion of tne second part 21 produces a residual force within the sealing material 23 acting to bias the rear face 32 of tne flange 26 into contact witn tne retaining face 28 of the groove 27.

Altnough tne invention has been described by way or exampie with reference to a water cooling circuit for an internal combustion engine it will be appreciated that it could be similarly used in a thermostatically controlled oil cooling circuit.

Similarly, altnougn the thermostat assembly nas seen described as being interposed between tne bottom tanK ot tne radiator and tne circulation pump it could equally De positioned between tne engine and tne top tanK of the radiator.

Claims

ChAI.'lS

1. A thermostat assemoly for a cooling circuit of an internal combustion engine comprising a first resilient part, a second resilient part and a thermostat mountea within a chamber defined by said first and second parts.

2. A thermostat assemoly is claimed in Claim 1 in whicn tne first resilient part is made from a synthetic plastic material.

3. A tnermostat assemoly as claimed in any preceeding laim in which tne second part is made from a synthetic plastic material.

4. A tnermostat assemoly as claimed in Claim 2 or in claim 3 in which tne synthetic plastic material is a reinforced polyamide material.

5. A thermostat assemoly as claimed in any preceeding claim in which tne first resilient part defines a bore for cooperation with tne second part, tne chamber in which is located said thermostat and at least one conduit for connection of said chamber to tne cooling circuit of tne engine with which the assembly is associated in use.

6. A thermostat assemtaly as claimed in Claim 5 in which snap-locK connection means are provided within said sore and on said second part to provide a connection oetween said first and second parts upon insertion of tne second part into the bore of the first part.

7. A tnermostat assemoly as claimed in Claim 5 or in Claim u in which the bore of tne first resilient part nas a circumferential groove defined therein for cooperation witn a circumferential flange on tne second part to -orm said snap lock connection means.

d. thermostat assemoly as claimed in any of iaims 5 to 7 in which the thermostat nas a circumferential flange oy wnicn it is located and secured in the oore of tne first resilient part.

9. A thermostat assembly as claimed in Claim 8 in which tne side faces of the circumferential flange nave resilient sealing material attached thereto.

lU. A thermostat assembly as claimed in Claim 9 in which tne resilient sealing material provides a seal between the first and second parts.

11. A thermostat assemoly as claimed in Claim 9 or in Claim 1U in which the resilient sealing material biases tne flange of the second part against one face of tne circumferential groove.

12. A thermostat assemoly as claimed in Claim 10 or in Claim 11 in which the resilient sealing material is compressed between an annular face in tne oore or tne first resilient part and an end face of tne second part.

13. A thermostat assembly as claimed in any preceding Claim in wnicn tne first part has push fit coupling means tnereon for connecting tne first part to tne cooling circuit witn which it is associated in use.

14. thermostat assemoly as claimed in any preceding Claim ln which the second part nas push fit coupling means tnereon for connecting tne second part to tne cooling circuit with wnicn it is associated in use.

L5. A thermostat assemoly as claimed in Claim 13 or in Claim 14 in which the push fit coupling means is an ' o ' ring seal located in a groove.

16. A thermostat assembly for a cooling circuit of an internal combustion engine substantially as described herein witn reference to tne accompanying drawings.

17. A cooling circuit for an internal combustion engine including a tnermostat assembly as claimed in any of claims 1 to 10 in which tne cooling circuit is a water cooling circuit.

18. A cooling circuit for an internal zo.nDustion engine including a thermostat assemoly as claimed in any of claims 1 to 1U in which the cooling circuit is an oil cooling circuit.

19. cooling circuit for an internal combustion engine including a thermostat assemoly as claimed in Claim 14 ih wnicn tne thermostat assembly is connected into tne cooling circuit by means of two push fit coupling.

20. A cooling circuit for an internal combustion engine suostantially as descriDed nerein witn reference to tne accompanying drawings.