WO2000068552A1

WO2000068552A1 - Combustion engine with supercharger

Info

Publication number: WO2000068552A1
Application number: PCT/SE2000/000941
Authority: WO
Inventors: Benny Lindbrandt; Håkan SALETTI
Original assignee: Lysholm Technologies Ab
Priority date: 1999-05-11
Filing date: 2000-05-11
Publication date: 2000-11-16
Also published as: AU4964800A; SE9901704L; SE9901704D0

Abstract

The invention relates to an internal combustion engine that includes at least a supercharger which has at least one rotor (6) which is driven by a rotating engine and which includes a driven shaft (10) and is rotatably mounted in a cylindrical working chamber in a supercharger housing (5). For practical reasons, the supercharger is united with the engine as close as possible thereto and, in operation, is heated by the transfer of heat from the engine and by internal compression processes, wherewith the supercharger is constantly subjected to varying thermal stresses. Such thermal stresses have been eliminated to a great extent by means of the invention, by virtue of surrounding the cyndrical working chamber of the supercharger with cooling channels (7) that communicate with the engine cooling channels (8).

Description

Combustion engine with supercharger

The present invention relates to an internal combustion engine equipped with a supercharger that includes at least one rotor which is driven by a rotating shaft of the motor and which includes a drive shaft and is mounted for rotation in a cylindrical working chamber in a supercharger housing.

The internal combustion engine and the supercharger normally attached to the engine undergo mutually different thermal variations in operation, which in extreme cases can result in significant mechanical stresses and subsequent risk of damage. After being started-up, the engine reaches a normal, constant operating temperature relatively quickly, whereas the temperature of the supercharger is dependent partly on the conduction of engine heat through the material of the supercharger, and partly on the operational mode of the supercharger. When the engine is started in extreme low temperatures, e.g. in temperatures of -30°C or lower, the lubricating oil in the supercharger is highly viscous and the clearance between components that move relative to one another is disadvantageous. Thermal stresses also occur between the engine and the supercharger housing. This drawback also occurs in normal operation as the temperature of the supercharger housing falls when only a slight pressure is applied to the accelerator and the supercharger consequently is inactive and subjected to the effect of a cold head wind, and thereafter rise quickly when the engine is accelerated and the supercharger therewith becomes active.

The object of the present invention is to provide a simple and effective solution to these problems and also a solution which provides further improvements to an internal combustion engine of the aforedescribed kind. This is achieved in accordance with the invention with an internal combustion engine designed in accordance with Claim 1. Further improvements will be apparent from Claims 2-8.

The provision of cooling channels that surround the cylindrical working chamber of the supercharger and the connection of these channels to the engine cooling system, as stated in Claim 1, results in equalization of the temperature differences between the engine and the supercharger housing. The best effect will, of course, be achieved when liquid coolant circulates in the cooling channels. As the supercharger housing normally includes lubricant channels, it is suitable to arrange said channels so that they communicate with the engine oil channels through which pressure oil circulates. The temperature of the lubricating oil in the supercharger is also effectively regulated in this way. In order to benefit effectively from the possibility of utilizing the heat generated by the supercharger before it is subjected to full load, there is conveniently connected to the clutch between the engine shaft and the supercharger drive shaft a device which detects the temperature in the supercharger housing and which prevents actuation of said clutch whilst the temperature detected is beneath a given threshold value. With the cooling channels of the supercharger and the engine, and possibly also their lubricant channels, integrated with one another, it is also appropriate to integrate the supercharger housing and the cylinder block or cylinder head of the engine, so as to obtain a compact construction in the absence of unnecessary hoses or pipes.

As disclosed in Claim 9, it may be appropriate in this respect to provide the su- percharger housing with an exchangeable lining that forms the inner surface of the actual cylinder space, similar to the way in which so-called wet cylinder linings are formed in car engines. One gain in this respect is that the temperature of the cylinder chamber in the supercharger is controlled very effectively, whilst another is that the lining can be easily replaced should the cylinder surface be damaged. The aforesaid integration enables the engine cooling system to be connected through the medium of internal channels, and also enables the lubricating system of an oil lubricated supercharger to be connected to the lubricating system of the engine through the medium of internal channels in which engine pressure oil circulates.

A supercharger will often include an hydraulically operated clutch. This clutch may also be connected to the engine hydraulic system through the medium of internal hydraulic fluid channels, via a regulating valve.

Modern engines are normally of the overhead valve type and include at least one overlying camshaft. In this case it is suitable to integrate the supercharger housing with the cylinder head of the engine, therewith suitably enabling a camshaft to be used to drive the supercharger. One further advantage with such integration, apart from enabling a camshaft to be used as a drive shaft, resides in the nearness to the engine induction channels. Such integration is particularly beneficial in the case of a V-type engine, in which the supercharger is built in between and together with the cylinder heads of the two banks of cylinders.

The invention will be described in more detail with reference to the accompanying drawings which illustrate schematically different embodiments of engines according to the invention and in which

Figure la is a cross-sectional view of a first embodiment of an inventive engine, taken on the line la-la i Figure lb;

Figure lb is a side view of the engine shown in Figure la;

Figure 2a is a cross-sectional view of a second embodiment of an inventive en- gme;

Figure 2b is a side view of the engine shown in Figure 2a;

Figure 3 is a cross-sectional view of a third embodiment of an inventive engine; and

Figure 4 is a cross-sectional view of the upper part of a further embodiment of an inventive engine.

Figure la illustrates an internal combustion engine that includes a cylinder block 1, a cylinder head 2, and an oil tray 3. The cylinder block includes on one side, on which the induction channels 4 are situated, a convex-dished enlargement that forms the housing 5 of a supercharger of the screw-compressor type. The housing 5 comprises a core 5a that includes external cooling fins 5 c which are fitted snugly in an outer cylindrical part 5b. Formed between the core 5a and the cylindrical part 5b is a space which surrounds said core and in which the cooling fins define therebetween a large number of cooling channels 7 that connect with the cooling channels 8 of the engine. Two screw rotors 6 are rotatably mounted in a cylindrical working chamber in the core 5a of the housing, said chamber being surrounded by the cooling channels 7. The supercharger housing 5 is disposed so far forwards on the cylinder block 1 that a pulley 10a mounted on a rotor drive shaft 10 projecting out from the front end- wall 9 of the housing 5 lies in the same plane as a pulley 11 mounted on the crankshaft of said engine, wherewith a supercharger drive belt 12 extends around the two pulleys 10a, 11. The supercharger has an inlet 13 situated on the rear end- wall, and an outlet 14 that opens into a channel 15 in the outer part of said cylindrical part 5b and extends upwards to a channel 16 in the cylinder head 2, where said channel has the same width as the line or bank of induction channels 4. This broad section of the channel 16 includes two water-cooled, series-connected heat exchangers 17 that are provided with external cooling fins and disposed in accordance with the method proposed in SE 9900041-6. The drive shaft 10 of the supercharger is provided conventionally with an hy- draulic disc clutch 18 which enables the supercharger to be disengaged when not required for use. Actuation of the clutch, is effected by means of devices (not shown) in conjunction with engine acceleration. In order to prevent actuation of the clutch when the temperature of the supercharger is below a given threshold value, the temperature sensing device 19 is installed in the supercharger housing for indicating such a tempera- ture state and for actuation of the clutch 18 through the medium of a pipe 24 that leads to a clutch-mounted valve (not shown).

The core 5 a and the cylindrical part 5b of the housing 5 include a removable end- wall part 9 which sealingly closes an opening situated in the front end of said core 5a and said cylindrical part 5b and through which a rotor drive shaft and its associated seal extend. After having removed the pulley 10a, the wall part 9 can be removed and the core 5a withdrawn from the cylindrical part 5b for service or replacement.

Figures 2a and 2b illustrate an alternative embodiment of the described supercharger and its drive mechanism. The entire supercharger housing 5 with core 5a and cylindrical part 5b are cast in one piece with the cylinder block 1 and with flanges or other spacing means for defining the cooling channels 7 surrounding the core 5a. A toothed wheel 20 firmly mounted on the crankshaft of the engine functions to drive a transmission 21 that extends through an opening 22 in the wall of the cylinder block 1 to a toothed wheel 23 firmly mounted on the drive shaft 10 of the supercharger. As a result of this internal drive, the supercharger will be located further to the rear of the engine in comparison with the Figure 1 embodiment. Another difference is that the channel 15 from the supercharger outlet 14 has been formed by a casing 25 sealingly mounted on the supercharger housing 5 and extending to the connections of the induction channels 4 where, as in the earlier case, the heat exchanger tubes 17 of the cooling arrangement are placed, as will be apparent from Figure 2b. As with the earlier embodiment, a tempera- ture sensor 19 is provided for preventing actuation of the clutch, when the temperature of the supercharger housing is below a given threshold value. As with the earlier embodiment, the cooling channels 7 of the supercharger of the Figure 2 embodiment are integrated with the engine cooling channels 8. Channels 26 are provided for conducting pressure oil to the supercharger housing 5 from the engine oil pump 27, for lubricating supercharger bearings and for supplying pressure oil to the disc clutch 18 normally included in the supercharger (Fig. 2b).

Figure 3 illustrates an embodiment of an inventive internal combustion engine in which the supercharger housing 5 is integrated with the cylinder head 2 of the engine. The supercharger housing 5 is positioned so that its outlet 14 is located opposite an inlet to a collecting chamber 13 of the kind proposed in said Swedish Patent Publication 9900041-6 and in which the heat exchanger tubes 17 of a cooling device are contacted transversely by the compressed air of combustion delivered to the line of induction channels 4 of an inline cylinder overhead valve engine. A pulley 31 on the supercharger drive shaft is driven by a belt 32 extending around a pulley 34 which is non-rotatably mounted on a camshaft 33. A corresponding arrangement is provided in the V-engine having overhead valves and shown in Figure 4. In this case, the supercharger housing 5 is placed between the cylinder banks 41, 42 with the outlet 14 of the supercharger facing down towards heat exchanging tubes 17 of the aforedescribed kind disposed in a distribution chamber 43. The outlet openings of the distribution chamber coincide with the rows of induction channels 4a, 4b of the two cylinder banks. As in the earlier case, a pulley 44 on the supercharger drive shaft is driven by a belt 46 which extends around said pulley and also around a pulley 45 non-rotatably mounted on a camshaft.

The embodiments illustrated in Figures 3 and 4 also include a temperature sensor 19 which functions to sense the temperature of the supercharger housing and to prevent actuation of a clutch (not shown) corresponding to the clutch 18 when the temperature sensed is below a given threshold value.

It will be understood that the invention is not restricted to the illustrated and described embodiments thereof and that modifications can be made within the scope of the inventive concept defined in the accompanying claims. For instance, the invention can be applied with superchargers other than screw-rotor type. Other types of intermediate coolers may be used, although it may be difficult to position coolers of other types. The invention can also be applied to air-cooled engines and air-cooled superchargers.

Claims

1. An internal combustion engine that includes a supercharger which has at least one rotor (6) which is driven by a rotating engine shaft and which includes a drive shaft (10) and is rotatably mounted in a cylindrical working chamber in a supercharger housing, characterized in that the cylindrical working chamber in said housing (5) is surrounded by cooling channels (7) that communicate with the cooling channels (8) of said engine.

2. An internal combustion engine according to Claim 1 , characterized in that respective cooling channels (8 and 7) of the engine and supercharger contain circulating liquid coolant.

3. An internal combustion engine according to Claim 1 or 2, characterized in that the supercharger housing includes lubricating oil channels that communicate with the engine oil channels (26) containing circulating pressure oil.

4. An internal combustion engine according to any one of Claims 1-3, characterized by means (19) for sensing the temperature in the supercharger housing, said means being connected to a clutch (18) which is mounted between the rotary shaft of said engine and the drive shaft (10) of said supercharger, wherein the temperature sensing means (19) is adapted to prevent actuation of the clutch (18) when the temperature sensed is beneath a given threshold value.

5. An internal combustion engine according to any one of Claims 1 -3, characterized in that the supercharger housing includes pressure oil channels for controlling an hydraulically operated supercharger clutch, said channels communicating with the pressure oil system (26,27) of the engine for manoeuvring said coupling via a control valve.

6. An internal combustion engine according to any one of Claims 1-5 that includes at least one camshaft (33) in a cylinder head (2), characterized in that the supercharger housing (5) is integral with that part of the engine housing comprised of the cylinder head (2) and associated cylinder head casing; and in that a supercharger drive shaft (31) is in drive connection with said camshaft (33).

7. An internal combustion engine according to any one of Claims 1-5, character- ized in that the supercharger housing (5) is integrated with that part of the engine housing comprised of the cylinder block (1); and in that a supercharger drive shaft (10) is in drive connection with the engine crankshaft (20) via a transmission (21) that extends through an opening (22) in the wall of the cylinder block (1).

8. An internal combustion engine according to any one of Claims 1 -5, characterized in that the supercharger housing (5) is integrated with that part of the engine housing comprised of the cylinder block (1); and in that a supercharger drive shaft (10) is in drive connection with the engine crankshaft (11) via a belt transmission (12) disposed on the outside of the engine housing and supercharger housing respectively.

9. An internal combustion engine according to any one of Claims 1-8, characterized in that the cylinder chamber of the supercharger is constructed with a replaceable lining having an outer surface which forms a wall against the cooling channels of the supercharger