GB2062749A

GB2062749A - Internal Combustion Engine With EGR Cooler

Info

Publication number: GB2062749A
Application number: GB8032675A
Authority: GB
Original assignee: Ford Motor Co Ltd; Ford Motor Co
Current assignee: Ford Motor Co Ltd; Ford Motor Co
Priority date: 1979-10-09
Filing date: 1980-10-09
Publication date: 1981-05-28
Also published as: DE3034971C2; DE3034971A1; GB2062749B

Abstract

An exhaust gas recirculation (EGR) cooler or heat exchanger is constructed for direct mounting to the engine intake manifold, the cooler being flat and having an engine coolant inlet 46 at one end of an oblong casing 44 and a coolant outlet 48 at the other end to flow coolant past a U-shaped tube 60 containing EGR gases to be cooled. <IMAGE>

Description

SPECIFICATION Engine With EGR Cooler This invention relates in general to internal combustion engines.

Known internal combustion engines for motor vehicles comprise a cylinder block, an engine intake manifold connected to the block, and an exhaust gas recirculation (EGR) system included in the intake manifold.

It is known to include EGR coolers in EGR systems. For example, U.S. 3,937,196 shows and describes an internally mounted EGR cooler. In this case, the intake manifold is designed specifically to accept such a cooler. Such design, however, generally will be more complicated and less economical than a conventional intake manifold with an externally mounted EGR cooler.

Figure 1 shows a known type of externally mounted EGR cooler 1 in which water or engine coolant is circulated between tubes 2 and 4 through an outer cylinder of the cooler than contains an internal cylinder through which exhaust gases flow from a tube 6 to a conduit 8 to be recirculated into the engine through an EGR valve 9. This system is typical of many of the externally mounted EGR coolers in that it is a mish-mash of tubes, insulator socks, brackets, hoses, clamps and fittings providing an awkward arrangement.

According to the present invention, there is provided an internal combustion engine comprising a cylinder block, an engine intake manifold connected to the block, the intake manifold includes an exhaust gas recirculation (EGR) system, and an EGR gas cooler characterised in that the EGR gas cooler is mounted on the underside of the manifold and is connected to the EGR system for cooling of the EGR gases by engine coolant.

Preferably, the engine is of V-type, which has a dual bank of cylinders defining a valley therebetween, the manifold being connected to both banks of cylinders, and the cooler being nested in the valley.

Where the EGR system is totally contained within the intake manifold, the EGR cooler can be constructed as a flat compact unit contiguous with the underside of the manifold in the valley between the two banks of engine cylinders thereby eliminating the usual external tubes, hoses, insulator socks, brackets and other paraphernalia usually associated with an externally mounted EGR cooler.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawings, in which: Figure 1 is a view of an EGR cooler assembly known in the prior art; Figure 2 schematically illustrates, in exploded view form, a V-8 type engine construction embodying the invention; Figure 3 is an enlarged top or plan view of the intake manifold shown in Figure 2; Figure 4 is a bottom view of the intake manifold shown in Figure 3, looking up; Figures 5 and 6 and 7 are cross-sectional views of portions of the intake manifold taken on planes indicated by and viewed in the direction of the arrows 5-5 and 6-6 and 7-7 of Figure 3, and illustrating the path of movement of the EGR gases; Figure 8 is a reproduction of a portion of Figure 3;; Figure 9 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows 9-9 of Figure 3; Figure 10 is a perspective view of the cooler installed on the intake manifold; Figure 11 is an enlarged plan view of the cooler shown in Figure 10; Figure 12 is a longitudinal cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows 12-1 2 of Figure 1 1; and Figures 13 and 14 are cross-sectional views taken on planes indicated by and viewed in the direction of the arrows 13-13 and 14-14, respectively, of Figure 11.

As indicated previously, the invention relates to the provision of an EGR cooler that can be easily integrated into a V-8 type engine construction, without incorporating the usual hoses, clamps, tubes and other paraphenalia normally associated with externally mounted EGR coolers. In this instance, the EGR cooler is snugly received in a nesting manner beneath the intake manifold in the valley of the V-8 and cooperatingly constructed to coact with internal EGR passages in the intake manifold.

Figure 2 illustrates in a schematic exploded view an automotive type internal combustion engine of the conventional V-8 type. It consists of the normal dual bank of engine cylinders or blocks 10 that are joined at their lower or bottom crankcase ends and spaced laterally from one another at their upper cylinder head assembly ends 12, as shown. This defines the usual valley 14 within which normally is mounted a single intake manifold 1 6 having passages interconnecting the two cylinder blocks. In this case, as illustrated, a compact, flat sandwich type EGR cooler 1 8 is fitted between the bottom of the intake manifold and a combination cover-gasket 20 normally provided for the valley.As will be described, the EGR cooler 1 8 is integrally mounted to the underside of the intake manifold and has passages for circulation of engine coolant through it and around a tubular member that contains the EGR gas to be recirculated into the engine, as previously described.

Figure 3 is a top view of the intake manifold shown in Figure 2. It contains the usual carburetor mounting flange 30 having two riser bores 32 that are adapted to mate with the riser bores of a downdraft type carburetor (not shown). The bores are interconnected with the conventional logs or runners 34 that connect at opposite edges to the engine cylinder heads for distribution of the air/fuel mixture from the carburetor into the engine proper. The manifold also contains front and rear water passages 36 and 38 for the flow of engine coolant between the cylinder blocks and heads in a known manner.

As best seen in Figures 4, 5, and 7 the manifold also contains an exhaust gas crossover passage 40 connecting the exhaust gases from one bank of engine cylinder to the opposite bank, flowing directly beneath the riser bores 32 for evaporating liquid fuel in the air/fuel mixture prior to its entry into the engine cylinders.

Exhaust gas recirculation (EGR) systems have been in use of automotive engine installations for many years to control the production of Nqx. The usual construction is to tap the exhaust gas crossover passage 40 for a supply of exhaust gases, and redirect this portion of the gases into the engine intake manifold generally at a location below the throttle valve of the carburetor and above the inlet to the intake manifold. This generally lowers the combustion chamber pressures and temperatures to reduce the output of NOx. The use of hot exhaust gases, however, may lead to a greater evaporation of the air/fuel mixture flowing through the carburetor than is desired. Accordingly, an EGR cooler may be desired to cool the exhaust gases prior to their reentering the intake manifold on their way to the engine cylinders.

This invention relates to an EGR system that is essentially totally contained within the intake manifold, and is primarily concerned with an EGR cooler that Is mounted integral to the manifold without the usual appertinences, so as to simplify the construction and provide better assembly reliability.

Tuming now to Figures 4-6 and 9, the EGR passage 40 is provided with a gas outlet or discharge opening 42 for the passage of EGR gases downwardly out of the intake manifold.

Bolted directly to the underside of the intake manifold is a flat, sandwiched-shaped EGR cooler 18 which, as best seen In Figures 10--14, has an elongated oblong type hollow casing 44. The casing is provided with flanged openings at opposite ends constituting an engine coolant inlet 46 and a coolant outlet 48. These openings are aligned directly with mating openings 50 and 52 in the manifold coolant passages 36 and 38. The casing 44 also contains a third mounting flange 54 that contains a pair of openings 56 and 58.

Secured within the latter openings are the open ends of a tube 60 that is bent into a U-shape to provide an arcuately shaped base portion 62 and a pair of legs or leg portions 64 extending from it.

The side or leg portions are spaced laterally from each other by a partition-like combination support-spacer 66 that is fixedly secured within casing 44 closely adjacent to flange 54. The support-spacer 66 has a first pair of spaced holes 68 through which are inserted the legs 64 of the U-shaped tube. A second set of arcuately shaped holes 70 is also provided to permit the flow of water or engine coolant through casing 44 from inlet 46 to outlet 48 past all portions of the tube 60. The tube is shown as tapering or diverging outwardly directly downstream of support-spacer 66 to provide a greater heat transfer or heat exchange between the engine coolant and the walls of the U-shaped tube.

The tube in this case is adapted to contain and flow exhaust gases from the engine EGR system that in this case is totally contained within the intake manifold. The opening 56, therefore, is adapted to be aligned with the gas outlet 42 from the engine exhaust gas crossover passage 40, with the flange 54 being secured directly to the underside of the intake manifold. The opening 56 in the casing of the EGR cooler, therefore, constitutes an outlet for the flow of cooled exhaust gases into an opening 72 provided in the intake manifold for flow upwardly and diagonally through a passage 73, as indicated in Figure 9. As best seen in Figure 8, the topside of the intake manifold is cored to provide a pair of essentially parallel passages 74 and 76 terminating in a mounting flange 78. Passage 74 is connected directly to the diagonal passage 73 to receive the cooled exhaust gases.Passage 76 on the other hand is connected through dual ports 80 directly into the riser bores 32. The exhaust gases in passage 74 at times will be connected with the passage 76 so that they then can flow into the riser bores 32 and be circulated into the intake manifold and therethrough to the engine cylinders.

The mounting flange 78 in this case is adapted to support a known type of reciprocating EGR control valve (not shown) that would be movable either electronically, by vacuum or other suitable means to block or unblock communication between the two passages 74 and 76, in a known manner. In brief, the flow of exhaust gases generally is not desired during engine idle speed and wide open throttle conditions of operation, since at engine idle, the scavenging of exhaust gases is not as efficient as at off idle speeds of operation, and at wide open throttle conditions of operation, the maximum power output is determined by the availability of oxygen.

Accordingly, the EGR valve normally will close off the connection between passages 74 and 76 to prevent passage of EGR gases into the throttle riser bores at these times, and will schedule the flow of EGR gases generally only during off idle, part load conditions of operation.

As thus described, therefore, it will be seen that the engine water or coolant, as the case may be, flows through the intake manifold passage 36 and out the opening 50 into the inlet 46 of the EGR cooler. The coolant then flows longitudinally through the casing 44 towards the coolant outlet 48, passing through holes 70 to totally surround the legs and base of the U-shaped EGR cooler tube 60. It thereby provides a transfer of heat from the hot exhaust gases to the cooler engine coolant. The coolant then passes out into the intake manifold passage 38 at the rear of the engine for flow to the engine radiator to be cooled and recycled for use again in the cooler and other portions of the engine. During this time, a portion of the exhaust gases flowing through the crossover passage 40 are diverted into the outlet 42 and into the inlet 56 of the U-shaped tube 60.

From there, the EGR gases flow around the circuit of the U-shaped tube and out the outlet 58 into the diagonally located passage 73 and into passage 74. If the EGR valve is in an open condition, the exhaust gases will continue to be pulled, by reason of the engine intake manifold vacuum, into the riser bores 32 through the openings 80.

Figures 11-14 illustrate more clearly the specific construction of the EGR cooler 1 8. As stated previously, it has the three mounting flanges adapted to be attached to matingly shaped flanges formed on the underside of the intake manifold, the openings 56 and 58 cooperating with the inlet and outlet 42 and 72, respectively. Figures. 13-14 more clearly show the cross-sectional constructions.

From the foregoing, it will be seen that the invention provides an EGR cooler that can be mounted directly to the underside of the engine intake manifold in the valley of a V-8 type engine thus providing a compact and simplified construction without the use of additional brackets, hoses, fittings and clamps. The simplification of this design provides improved assembly reliability, lower assembly costs, reduced weight and an improved EGR system and engine function. The integral EGR cooler and manifold system also provides an improved package that minimizes damage in engine shipment and in engine installation at the vehicle assembly plants.

While the invention has been shown and illustrated in its preferred embodiment, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.

Claims

1. An internal combustion engine comprising a cylinder block, an engine intake manifold connected to the block, the intake manifold includes an exhaust gas recirculation (EGR) system, and an EGR gas cooler characterised in that the EGR gas cooler is mounted on the underside of the manifold and is connected to the EGR system for cooling of the EGR gases by engine coolant.

2. An engine according to Claim 1, in which the engine is of the V-type and has a dual bank of cylinder blocks defining a valley therebetween, the manifold is connected to both banks of cylinders and the cooler is nested in the valley.

3. An engine as in Claim 1 and Claim 2 wherein the EGR system is totally contained within the intake manifold for tke flow of exhaust gases from the exhaust manifold through the intake manifold to the engine cylinders.

4. An engine according to any one of Claims 1 to 3 wherein the exhaust gas flow passages connecting engine exhaust gases to carburettor air/fuel flow inlet riser bores are integral with the manifold and are adapted to be connected to an EGR control valve mechanism operable to control flow through the passages, the cooler having an engine coolant inlet and an outlet each connected to the engine coolant flow passages, the cooler also having an EGR gas inlet and outlet connected to the exhaust gas flow passages for cooling of the EGR gases by the engine coolant.

5. An engine according to any one of Claims 1 to 4 wherein a combination valley cover and gasket are located in the valley beneath the intake manifold, the cooler being nestled between the intake manifold and the cover-gasket.

6. An engine according to Claim 5, the cooler being flat so as to nestle between the cover and the intake manifold.

7. An engine according to any one of Claims 1 to 6 wherein the intake manifold contains an exhaust gas crossover passage connected at opposite ends to the exhaust manifold in each bank, the latter passage containing a connection to the gas inlet of the EGR gas cooler, the EGR gas outlet by-passing the crossover passage and being adapted to be connected to the EGR control valve mechanism.

8. An engine according to any one of Claims 1 to 7 wherein the cooler comprises a flat sandwich-type casing mounted contigous to the manifold and connected to both the engine coolant system and to the EGR system for cooling of the EGR gases by engine coolant, the casing being of tubular oblong shape connected at opposite ends to engine coolant passages in the manifold, and an essentially U-shaped tube mounted within the casing surrounded by coolant and having the open pair of end portions of the tube connected one to the EGR system to constitute an inlet for receiving EGR gases therein and the other connected to the EGR system to constitute an outlet for the discharge therefrom of the exhaust gases cooled by heat transfer to the coolant.

9. An engine according to Claim 8 wherein the coolant inlet and outlet extend through the top portion of the casing essentially at right angles to the direction of coolant flow longitudinally through the cooler.

10. An engine according to Claim 8 or Claim 9 wherein the coolant inlet and outlet and EGR gas inlet and outlet are all in the same plane and extend through that portion of the cooler contiguous with the manifold.

11. An engine according to any one of claims 8 to 10 wherein the cooler includes a plurality of flange manifold mounting means fixed one to each of the coolant inlet and outlet and a further one to the EGR gas inlet connection to the EGR system.

12. An engine according to any one of Claims 8 to 11 wherein the U-shaped tube has a pair of side leg portions extending from an arcuate base portion, the side portions flaring laterally away from one another at a location in the casing closer to the EGR gas inlet and outlet than to the base member to Increase the coolant flow area between the side portions for a greater heat transfer.

13. An engine according to any of Claims 8 to 12 wherein the cooler includes an upright tube support member secured within the casing adjacent the EGR gas inlet and outlet, the tube having a pair of leg portions secured to a base member, the support member having a first pair of laterally spaced openings each receiving therethrough one leg portion, the support member having a second pair of openings therethrough from the flow of coolant therethrough.

14. An engine substantially as hereinbefore described, and as illustrated in the drawings.