GB2478006A

GB2478006A - An engine intake tumble flow plate

Info

Publication number: GB2478006A
Application number: GB1003051A
Authority: GB
Inventors: Peter Rothenberger; Winfried Rogge
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2010-02-23
Filing date: 2010-02-23
Publication date: 2011-08-24
Also published as: GB201003051D0

Abstract

An air intake system 51 for combustion engines and more particularly for the generation of tumble flow 59 for good fuel-air mixing homogeneity via continuous adjustment of a shutoff plate 53 from a plurality of tumble configurations to a non-tumble configuration, in which the shutoff plate 13 is fully retracted from the air intake system 51, so that no unwanted flow losses occur. Adjustment of the plate 53 may be via an up-down or sideway movement wherein the actuator 54 may take the form of an eccentric pin 55 driven by a rotatable disc or a tiltable pin connected to a rotatable shaft. The rotatable shaft or disc being driven by an electric motor, a pneumatic or hydraulic device, a Bowden cable or memory metal.

Description

Device for creating a tunble flow

Description

The invention relates to the field of air intake

systems for combustion engines and more particularly to the creation of tumble flow for good fuel-air mixing homogeneity.

From the state of the art it is known that high exhaust gas recirculation rates are a way to reduce fuel consumption of combustion engines by recirculating a portion of an engine's exhaust gas back to the engine cylinders. In a gasoline engine this inert exhaust reduces the amount of combustable matter in the cylinder thereby leading to less heat generation during combustion. At the same time the combustion still creates the same pressure against the piston at lower temperature. In a diesel engine, the exhaust gas replaces some of the excess oxygen in the pre-combustion mixture.

Moreover, exhaust gas recirculation is a nitrogen oxide (NOx) emission reduction technique used in most petrol/gasoline and diesel engines. Since NOx forms primarily when a mixture of nitrogen and oxygen is subjected to high temperature, and exhaust gas recirculation lowers the temperature of combustion, the technique effectively reduces the amount of NOx generated during the combustion.

Apart from exhaust gas recirculation, in-cylinder flows such as tumble and swirl have an important influence on engine combustion efficiencies and emission formation. In particular, tumble flow, which is dominant in current high performance combustion engines, has an important effect on fuel consumption and exhaust emission under part-load conditions, since a high tumble flow motion leads to good fuel-air mixing homogeneity, which is a prerequisite for efficient combustion in the engine cylinder.

One example of a system aiming at generating tumble flow in order to maximise engine combustion efficiencies and minimize emission formations is described in EP085279A2. In this example the intake system of a combustion engine includes a plurality of primary intake runners and a slot spaced from either end of the primary runner, extending at least partially around its periphery. A throttle plate is mounted in and extends across the slots, with the throttle plate also including a plurality of openings therethrough operatively engaging the slots. By moving the plate the plurality of openings will selectively block off portions of the intake runners and thus can provide tumble port control as well as engine throttling, and also port deactivation if so desired.

It is a disadvantage of such kind of system that the alignment of the openings with the slots has to match perfectly; otherwise unwanted flow losses will occur in completely open position during full load. This perfect alignment, however, is difficult and hence expensive to control.

Another solution to achieve both tumble flow and high exhaust gas recirculation rates exists, where a moulded separating plate is needed in the passages and tumble throttles are situated in the middle of the intake runner.

It is a disadvantage of such kind of a solution that the built-in components always lead to unwanted flow losses in completely open position during full load. I0

It is the object of the present invention to provide a device for the creation of a tumble flow in the air intake system of a combustion engine that does not cause unwanted flow losses during full load.

It is another object of the present invention to provide a device for the creation of a tumble flow in the air intake system of a combustion engine, which is less complicated to manufacture and hence more cost-effective than devices known from the art.

The solution of the objects is achieved by the features of claim 1. Preferred embodiments are given in the dependent claims.

These and other aspects of the invention will be apparent from and elucidated with reference to a preferred embodiment described hereinafter.

The invention is directed at a device for creating a tumble flow in an air intake system of a combustion engine, said device comprising: a) a shutoff plate which is disposed near the air intake system, and b) an actuator capable of continuously adjusting the position of said shutoff plate with respect to the intake system, in such a way that the shutoff plate can be continuously actuated from a plurality of tumble configurations, in which the shutoff plate is adjusted to block between »= 0,1 % and «= 80 % of the intake system's cross section, to a non-tumble configuration, in which the shutoff plate is fully retracted from the air intake system's cross section.

Thus, if the shutoff plate is situated in one of the plurality of tumble configurations, it partially blocks the air intake system's cross section thereby creating a tumble flow. This tumble flow in turn leads to optimal fuel-air and/or fuel-air-exhaust mixing homogeneity, which is a prerequisite for efficient combustion in the engine cylinder and hence for better fuel economy and reduced emission rates. During full load, on the other hand, the shutoff plate can be fully retracted from the air intake system's cross section thus preventing unwanted flow losses.

The device according to the invention enables better fuel economy as the creation of tumble flow is combined with gas recirculation. Moreover it is more cost effective during manufacture as the shutoff has no openings, thus only the shutoff plate itself has to match the dimensions of the air intake system but no matching between an opening and an intake runner or intake port has to be ensured. Additionally every cross section in the air intake system, that is to be blocked, only needs one opening in order to enable continuous adjustment of the shutoff plate as the plate only has to be moved into the air intake system, but not through it. Thus the complexity and hence the cost of the system are reduced.

As used herein the term "shutoff plate", refers to a plate that has no openings, which is disposed near the air intake system and which can be actuated by an actuator.

The term "continuous adjustment" as used herein, refers to a stageless i.e. infinitely variable movement of the shutoff plate.

JO The term "air intake system" as used herein, refers to a channel, in which the air and/or the air/exhaust mixture of the intake system flows e.g. it refers to a plenum and/or an intake port and/or an intake runner.

The term "actuator" as used herein, refers to the driving element that moves the shutoff plate i.e. it takes energy for instance created by muscles, air, electricity or liquid and converts it into motion.

Examples of possible actuators include plasma actuators, pneumatic actuators, electric actuators, motors, hydraulic cylinders and linear actuators.

The term "tumble configurations" as used herein, refers to positions of the shutoff plate that will, by partly blocking the air intake system, create a tumble flow in the at least one cylinder of the combustion engine thereby leading to better fuel-air and/or fuel-air-exhaust mixing homogeneity and overall to better fuel economy and fewer emissions.

In such case, it is preferred that the shutoff plate blocks between »= 0,1 % and «= 1% i.e. 0,1, »=0.2, »= 0.3, »= 0.4, »= 0.5, »= 0.6, »= 0.7, »= 0.8, »= 0.9 or «= 1 % of the intake system's cross section. It is even more preferred that the shutoff plate blocks between 1 % and «= 10% i.e. »=l, »=2, »=3, »=4, »=5, »=6, »=7, »=8, »=9 or «= 10 % of the intake system's cross section. It is even more preferred that the shutoff plate blocks between »= 10 % and «= 80% i.e. »= 10, »= 20, »= 30, »= 40, »= 50, »= 60, »= 70 or «= 80% of the intake system's cross section. It has to be understood that the most preferred value will differ with each engine type, since every engine type has its own requirements regarding the percentage that the shutoff plate blocks of the intake system's cross section in order to create optimal tumble flow.

The term "fully retracted" as used herein, refers a position of the shutoff plate where the plate is disposed completely outside of the air intake system, so that no unwanted flow losses occur.

As used herein the term "opening", refers to an opening for example a slit through which the shutoff plate enters the air intake system. The opening preferably fits tight around the shutoff plate, if the shutoff plate is blocking the cross section of the intake system. If the shutoff plate is in non-tumble configuration i.e. retracted from the air intake system, the opening can for example be closed by the top of the shutoff plate itself, thereby preventing air flow though the opening. Alternatively the opening can be blocked by a flexible seal, which closes tightly when the shutoff plate is retracted but also permits passage of the shutoff plate.

In an alternative embodiment, the shutoff plate is clamped between intake manifold and cylinder head.

In a preferred embodiment the actuator comprises an eccentric pin which is driven by a rotatable disc, said pin engages in a slit or nut disposed in the shutoff plate (Fig. 1 and 2) As used herein the term "eccentric pin" refers to an eccentric i.e. to a member disposed in a rotating disc or axle with its centre offset from that of the axle.

The slit or nut of the shutoff plate allows the shutoff plate to follow the movement of the pin as shown in Fig. 1 and Fig. 2.

Through such an arrangement the shutoff plate can be retracted from or insert into the air intake system in order to cause tumble flow or to prevent unwanted flow losses depending on the requirements of the combustion engine, i.e. whether it is working in full load or not, at any given time.

Moreover this type of actuator is robust i.e. not error prone, easy to use with any kind of shutoff plate, space-saving and cost-effective. Therefore it has several advantages over actuators described in devices for creating a tumble-flow in the state of the art e.g. over a drum take up device. This is the case as the drum take up device can only be used in conjunction with metal foil, is bulky, error-prone and more expensive in manufacture.

In a different preferred embodiment the actuator comprises a tiltable pin connected to a rotatable shaft, said pin engages in a hole or a slit or a nut disposed in the shutoff plate (see Fig. 3 and Fig. 4) As used herein the term tiltable pin" refers to a mechanism, in which the pin is tilted rather than turned in order to adjust the shutoff plate.

The hole or slit or nut of the shutoff plate allows the shutoff plate to follow the movement of the pin as shown in Fig. 3 and Fig. 4.

This arrangement allows for an alternative way to retract and insert the shutoff plate into the air intake system in order to cause tumble flow or to prevent unwanted flow losses depending on the requirements of the combustion engine, i.e. whether it is working in full load or not, at a given time.

Again this type of actuator is robust i.e. not error prone, easy to use with any kind of shutoff plate, space-saving and cost-effective. Therefore it has several advantages over actuators described in devices for creating a tumble-flow in the state of the art e.g. over a drum take up device. This is the case as the drum take up device can only be used in conjunction with metal foil, is bulky, error-prone and more expensive in manufacture.

In a further preferred embodiment the actuator, which is preferably a rotatable disc or a rotatable shaft, is driven by at least one device selected from the group consisting of: a) an electrical motor, preferably a servo motor or a stepper motor b) a pneumatic and/or hydraulic device, and/or c) a bowden cable and/or d) a memory metal An electric motor uses electrical energy to produce mechanical energy, usually through the interaction of magnetic fields and current-carrying conductors. They may be powered by direct current (for example a battery powered portable device or motor vehicle), or by alternating current from a central electrical distribution grid. Electric motors may be classified by the source of electric power, by their internal construction, and by their application. A person skilled in the art has no problem choosing a suitable motor to drive the actuator for a given context the device according to the invention is used in.

A preferred type of electric motor is a servo motor, which operates on the principle of negative feedback, where the control input is compared to the actual position of the mechanical system as measured by some sort of transducer at the output. Any difference between the actual and wanted values (an "error signal") is amplified and used to drive the system in the direction necessary to reduce or eliminate the error.

Another preferred type of electric motor is a stepper motor, which is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. The motor's position can be controlled precisely, without any feedback mechanism.

A different preferred device driving the actuator is a pneumatic and/or hydraulic device.

Hydraulic devices convert hydraulic energy i.e. pressure and flow into mechanical energy usually rotation.

Pneumatic devices, on the other hand, convert energy of compressed air into mechanical work. Typically stored energy in the form of compressed air, nitrogen or natural gas enters the sealed motor chamber and exerts pressure against the vanes of a rotor. Much like a windmill, this causes the rotor to turn at high speed.

A further preferred device driving the actuator is a Bowden cable, which is a type of flexible cable used to transmit mechanical force or energy by the movement of an inner cable (most commonly of steel or stainless steel) relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of a helical steel wire, often lined with plastic, and with a plastic outer sheath. The linear movement of the inner cable is generally used to transmit a pulling force, although for very light applications over shorter distances push may also be used. Usually provision is made for adjusting the cable tension using an inline hollow bolt (often called a "barrel adjuster"), which lengthens or shortens the cable housing relative to a fixed anchor point. Lengthening the housing (turning the barrel adjuster out) tightens the cable; shortening the housing (turning the barrel adjuster in) loosens the cable.

Another preferred device driving the actuator is a memory metal i.e. a metal or an alloy that "remembers" its original, cold, forged shape, and which returns to that shape after being deformed by applying heat.

In a preferred embodiment the device is disposed in close proximity to but upstream of a cylinder head of the combustion engine.

The term "in close proximity" as used herein, refers to a distance, which is small enough for a tumble flow created by the plate to reach the cylinder and thus lead to better fuel-air and/or fuel-air-exhaust mixing homogeneity and overall to better fuel economy and fewer emissions.

The term "upstream" as used herein, refers to the direction of air flow through the air intake system to the cylinders i.e. upstream of the cylinder refers to a position, which the air passes before it reaches the cylinder.

By disposing the device in such a position it is ensured that the tumble flow created by a shutoff plate in tumble configuration will reach the cylinder and hence facilitates a good fuel-air and/or fuel-air-exhaust mixing homogeneity.

A preferred example of such a position is disposing the device and especially the shutoff plate immediately in front of the cylinder head of the combustion engine, thus between the end of the intake runner and the intake port.

In a preferred embodiment the shutoff plate is made from a) steel and/or b) plastic and/or c) aluminium and/or d) fiber glass and/or e) fixed sheet metal.

In case steel is used, the shutoff plate preferably has a thickness of 1 mm, in contrast, if one of the other materials listed above is employed, the shutoff plate preferably has a thickness of 3 mm.

Whereas steel has the advantage that it is very strong the other materials are also favourable since they are light.

In an alternative embodiment the combustion engine comprises multiple devices. Such an arrangement is beneficial, if the combustion engine has multiple cylinders, as each cylinder will typically have its own air intake system. Hence each air intake system preferably has its own shutoff plate. In a preferred variant of a combustion engine comprising multiple devices each shutoff plate is actuated individually for the different air intake systems of the different cylinders. This is especially beneficial if the air intake systems of the different cylinders are not alike.

For instance, the air intake systems could differ in shape or cross section, hence each of them would require a distinct percentage of blocking by the shutoff plate to generate optimal tumble flow. Hence, each shutoff plate should be actuated individually.

In an alternative embodiment the device comprises multiple shutoff plates, which are attached to one shaft, so that they can be controlled simultaneously. The shaft is movable by an actuator and thus drives the continuous adjustment of the shutoff plates in the air intake systems.

Furthermore depending on where the device, especially the actuator, can be fitted best in respect to possible other parts of the combustion engine or the context, in which the combustion engine is used in, the shutoff plate can enter the air intake system from the side, the top, the bottom or any other angle required.

In a preferred embodiment, however, the continuous adjustment of the device is an up-and down or sideward movement relative to the at least one air intake system of the combustion engine.

Preferred is furthermore a method for creating a tumble flow in an air intake system of a combustion engine comprising the steps of: a) providing an air intake system with a shutoff plate and an actuator and b) actuating the shutoff plate into a plurality of tumble configurations or to a non-tumble configuration depending on the requirements of the combustion engine.

Such method, in which the device is for instance part of the combustion engine of a car, could for example proceed as follows: First the air/exhaust gas mixture is drawn through the air intake system into an intake runner of a combustion engine. Immediately in front of a cylinder head of the combustion engine, thus between the end of the intake runner and the intake port, a shutoff plate is situated.

Since the engine is not operating under full load conditions in this example, the shutoff plate is in tumble configuration, for example blocking 66% of the cross section of the intake runner. Thus a tumble flow is created when the air/exhaust gas mixture passes the shutoff plate. This tumble flow is propagated into the cylinder of the combustion engine, where it leads to a good fuel-air/exhaust gas mixing homogeneity. As a result the engine efficiency is increased. Moreover as the exhaust gas is present during combustion, less heat develops, since less combustable matter is available, thus leading to less NOx generated by the combustion.

The following figures illustrate schematically the essential aspects of the invention. It is to be understood that the figures are by no means meant as to limit the scope of the invention.

In the drawings: Fig. 1 Shows in an exemplary fashion, a side view of a preferred embodiment of a device according to the invention comprising an actuator with an eccentric pin.

This eccentric pin is driven by a rotatable disc and engages in a slit disposed in a shutoff plate, thereby controlling the adjustment of the shutoff plate.

Fig. 2 shows, in an exemplary fashion, a front view of the device of Fig. 1, characterised in that the actuator comprises an eccentric pin, which is driven by a rotatable disc and engages in a slit disposed in the shutoff plate, thereby controlling the adjustment of the shutoff plate.

Fig. 3 shows, in an exemplary fashion, a side view of a preferred embodiment of a device according to the invention comprising an actuator with a tiltable pin.

This tiltable pin is connected to a rotatable shaft, which engages in a slit disposed in a shutoff plate, thereby controlling the adjustment of the shutoff plate.

Fig. 4 shows in an exemplary fashion, a front view of the device of Fig. 3, characterised in that the actuator comprises a tiltable pin connected to a rotatable shaft, which engages in a slit disposed in the shutoff plate, thereby controlling the adjustment of the shutoff plate.

Fig. 5 shows, in an exemplary fashion, a preferred embodiment of a device according to the invention, characterised in that a shutoff plate is located immediately in front of a cylinder of a combustion engine.

Fig. 1 shows a schematic drawing of a side view of a device 10 according to the invention. In this example the device 10 comprises an air intake system 11 with an opening 12 and a shutoff plate 13. An eccentric pin 15 engages in the shutoff plate through a slit 16. The eccentric pin 15 is driven by an actuator 14, here a rotatable disc 14. Whenever the pin 15 -through movement of the rotatable disc 14 -is actuated upwards, the shutoff plate 13 will enter the air intake system 11 through the opening 12 and block the cross section of the air intake system 11 to some extend, e.g. at the most upward position of the pin 15 relative to the rotatable disc 14 the shutoff plate 13, in this example, blocks 50% of the air intake system's cross section. When the pin 15 is at its most downward position relative to the rotatable disc 14 the shutoff plate 13 is fully retracted from the air intake system 11.

Fig. 2 shows a schematic drawing of a device 20, which is the same device as in Fig. 1. Thus it also comprises an air intake system 21 with an opening (not shown), a shutoff plate 23, an actuator 24, here a rotatable disc 24, an eccentric pin 25 and a slit 26.

From this front view of the device 20, the slit 26, in which the eccentric pin 25 engages, can be clearly seen.

In this example the slit 26 is necessary to allow for the relative movement of the eccentric pin 25 in relation to the shutoff plate 23 needed for continuous adjustment of the shutoff plate 23. Again whenever the eccentric pin 25 -through movement of the rotatable disc 24 -is actuated upwards the shutoff plate 23 will enter the air intake system 21 through the opening 22 and block the cross section of the air intake system 21 to some extend. When the pin 25 is at its most downward position relative to the rotatable disc 24 the shutoff plate 23 is fully retracted from the air intake system 21.

Fig. 3 shows a schematic drawing of a side view of a device 30 according to the invention. In this example the device 30 comprises an air intake system 31 with an opening (not shown) and a shutoff plate 33. A tiltable pin 35 engages in the shutoff plate 33 through a slit 36.

The tiltable pin 35 is driven by an actuator 34, here a rotatable shaft 34. Whenever the tiltable pin 35 -through movement of the rotatable shaft 34 -is actuated i.e. tilted upwards the shutoff plate 33 will enter the air intake system 31 through the opening 32 and block the cross section of the air intake system 31 to some extend.

When the tiltable pin 35 is not tilted the shutoff plate 33 is fully retracted from the air intake system 31.

Fig. 4 shows a schematic drawing of a device 40, which is the same device as in Fig. 3. Thus it also comprises an air intake system 41 with an opening 42, a shutoff plate 43, an actuator 44, here a rotatable shaft 44, a tiltable pin 45 and a slit 46. From this front view of the device 40, the slit 46, in which the tiltable pin 45, engages can be clearly seen. In this example the slit 46 is necessary to allow for the relative movement of the tiltable pin 45 in relation to the shutoff plate 43 needed for continuous adjustment of the shutoff plate 43.

Again whenever the tiltable pin 45 -through movement of the rotatable shaft 44 -is actuated i.e. tilted upwards the shutoff plate 43 will enter the air intake system 41 through the opening 42 and block the cross section of the air intake system 41 to some extend. When the tiltable pIn 45 is not tilted the shutoff plate 43 is fully retracted from the air intake system 41.

Fig. 5 shows a schematic drawing of a device 50 according to the invention. It comprises an air intake system 51 with an opening 52, a shutoff plate 53, an actuator 54, an eccentric pin 55, a slit 56 and a cylinder 57 (not shown) . In this example, the shutoff plate 53 blocks about 66% of the cross section of the air intake system 51 and the shutoff plate 53 is located immediately in front of the cylinder 57. Thus if air or an air/exhaust gas mixture flows along the air intake system 51 towards the cylinder 57, i.e. in direction of the arrow 58, the shutoff plate 53 will cause a tumble flow 59, which will reach the cylinder 57. Inside the cylinder the tumble flow 59 will lead to a good fuel-air and/ or fuel-air-exhaust mixing homogeneity and thereby to an efficient combustion producing fewer emissions.

EXAMPLES

Experiments have been done with two kinds of devices to demonstrate tumble flow creation.

In both cases the devices were situated in an air intake system of a combustion engine, more particularly between the cylinder-head end of an intake runner and the intake port. In this case the combustion engine had four cylinders and one air intake system for each cylinder i.e. also four shutoff plates one for each air intake system. The shutoff plates were made from fixed sheet metal.

Via continuously and simultaneously actuating the shutoff plates, up to 66% of the cross section of the intake runners were blocked. Thus the air was forced to flow over the top of the shutoff plates into the intake ports, which caused an asymmetry in the air flow. This asymmetry persisted up to the intake valves and caused a strong tumble flow in the cylinder, as demonstrated by flow measurements.

In inactive mode the shutoff plates were completely retracted from the air intake systems. Thus they did not impair the flow behaviour during full load.

Example 1

In this example the shutoff plates were actuated by an eccentric pin, which in turn was driven through a movable disc by an electric motor.

Example 2

In the second example the shutoff plates were actuated by a tiltable pin, which in turn was driven angle-dependent through a rotatable shaft by an electric motor. The pin engaged in a slit disposed in the shutoff plate.

Claims

CLAIMS1. Device (10) for creating a tumble flow (59) in an air intake system (11) of a combustion engine, said device comprising: a) a shutoff plate (13) which is disposed near the air intake system (11), and b) an actuator (14, 34) capable of continuously adjusting the position of said shutoff plate with respect to the air intake system (11), in such way that the shutoff plate (13) can be continuously actuated from a plurality of tumble configurations, in which the shutoff plate (13) is adjusted to block between »= 0,1 % and «= 80 % of the air intake system's cross section, to a non-tumble configuration, in which the shutoff plate (13) is fully retracted from the intake system's cross section.
2. Device according to claim 1, wherein the actuator (14, 34) comprises an eccentric pin (15) which is driven by a rotatable disc, said pin (15) engages in a slit (16) or a nut disposed in said shutoff plate (13)
3. Device according to claim 1, wherein the actuator (14, 34) comprises a tiltable pin (35) connected to a rotatable shaft, said pin engages in a hole or a slit (16) or a nut disposed in said shutoff pLate (13)
4. Device according to any of the aformentioned claims, wherein the actuator (14, 34), preferably the rotatable disc or the rotatable shaft, is driven by at least one device selected from the group consisting of: a) an electrical motor, preferably a servo motor or a stepper motor b) a pneumatic and/or hydraulic device, and/or c) a bowden cable, and/or d) a memory metal.
5. Device according to claim 1, wherein the device is disposed in close proximity to but upstream of a cylinder head (57) of said combustion engine.
6. Device according to claim 1, characterized in that the shutoff plate (13) is made from a) steel, and/or b) plastic, and/or C) aluminium, and/or d) fiber glass, and/or e) fixed sheet metal.
7. System comprising at least two devices according to claim 1, whose at least two shutoff plates (13) are disposed on one shaft.
8. Device according to claim 1, characterized in that the adjustment is an up-and down or sideward movement.
9. A method for creating a tumble flow (59) in an air intake system (11) of a combustion engine according to claim 1, comprising the following steps: a) providing an air intake system (11) with a shutoff plate (13) and an actuator (14, 34) and b) actuating the shutoff plate (13) into a plurality of tumble configurations or to a non-tumble configuration depending on the requirements of the combustion engine.