DK143518B - PRESSED COMBUSTION ENGINE SPECIFICALLY PRESSED DIESEL ENGINE - Google Patents

Description

143518

The invention relates to an internal combustion engine, in particular a diesel engine, with a turbocharger driven from the engine, which is designed to supply charging air to the engine, and an bypass between the outlet of the compressor and the turbine, which bypass of the engine may be permanently open, but which contains throttle means with at least one throttle passage, whose flow cross-section is variable to produce a pressure difference between the outlet of the compressor and the turbine approach.

The starting point of the invention is a system consisting of an internal combustion engine and one of the engine's exhaust gases driven turbo compressor, which delivers air at overpressure, partly to the engine cylinders and partly through a bypass line outside the engine directly to the turbine part's inlet. Installations of this kind are described in the two older Danish patent applications 2153/71 (now patent no. 140,291) and 2858/71 (now patent no.

128,952).

20 At the engine plants described in the two applications mentioned, it is a condition that during the operation of the engine the bypass line is constantly open, the compressor supplying through the bypass line the amount of air not consumed in the engine to the turbine which on this way is always enabled to work close to its pump or instability limit, which in turn causes the turbo compressor to work at a high efficiency in all operating conditions, regardless of variations in charge pressure and in the combustion engine's air consumption. A further effect of the high efficiency is that the temperature of the turbine's propellant gases remains within acceptable limits even at high charge pressure.

As already mentioned, in the two 35 older applications, it is assumed that the bypass line is constantly open and thus does not produce any noticeable drop in pressure, so that the pressures at the combustion engine's approach and departure are practically the same. Although this ratio has certain advantages, it also results in a less efficient flushing of the motor cylinders, which is particularly the case. noted by two-stroke engines, but also by high-performance four-stroke engines.

The technical problem, the solution of which is contemplated by the present invention, consists in preserving the advantages arising from the presence of a bypass line which can conduct all the air flow not occupied by the engine while at the same time providing improved rinsing. Furthermore, the invention aims to reduce the power consumption allowed to remove the exhaust gases from the engine cylinders and thus increase the utility output provided by the engine.

According to the invention, the problem is solved in that the throttle means are controlled substantially by the pressures before and after the throttle passage and in such a way that an increase of the pressure after the throttle passage leads to a decrease in the flow cross-section and an increase in the pressure before the throttle passage causes an increase in the flow-through cross-section, and the pressure difference induced by the throttle means changes in the same direction as the pressure in the circulation line before the throttle passage.

The substantially "pure" pressure control of the flow cross section automatically causes the pressure drop across the throttle bodies to be independent of the air flow through the throttle passage.

If the amount of air varies, the cross-sectional area automatically adjusts to the effect of the pressures in such a way that the pressure difference corresponding to the throttle passage is maintained. Thus, the pressure drop across the throttle means remains constant at a certain pressure prior to the throttle passage, even though the internal combustion engine's speed and thus with the amount of air consumed by the engine varies considerably, the latter again causing significant variations in the air flow through the bypass line.

Furthermore, for the optimum function of the overall system, it is very important that the pressure difference produced by the throttle bodies varies in the same direction as the pressure in the bypass line on the upstream side of the throttle passage. In other words, the pressure difference should grow as the rinse and charge pressure grows, and decrease 15 with decreasing rinse and charge pressure. It is particularly advantageous for the pressure difference to vary linearly or at least substantially linearly with the variation in the charge pressure before the throttle passage.

The invention causes the relationship between the compression ratio of the compressor part and the expansion ratio of the turbine part to remain constant. A consequence of this is that at any moment the power required to operate the turbine is obtained with minimum gas temperatures. Another consequence of the variation of the pressure difference as a function of the charge pressure is that the flushing of the internal combustion engine takes place under optimal conditions.

The control of the throttle means in the bypass line, mainly solely under the influence of the pressures before and after the throttle passage, is in itself a new feature, the advantages of which are explained above. It is also new to control the throttle means in such a way that the pressure difference produced by the throttle means varies in the same direction as the charge pressure on the upstream side of the throttle means. Finally, it is also new to use such a throttle in a bypass line, which is permanently open during operation of the plant, thereby allowing the compressor to operate near its instability limit.

According to the invention, the throttle means may comprise a movable guide member having surfaces influenced by the pressure prevailing before and after the throttle passage, respectively, in which the effective area of the faces of the control member affected by the pressure prior to the throttle passage is less than 10 shows the effective area of the faces of the control member which is affected by the pressure after the throttle passage. Hereby, with a constructively simple embodiment, a linear dependence is obtained between the pressure drop in the throttle passage and the pressure in the bypass line on the upstream side of the passage 15, expressed by the formula Δ P = a'P, where Δ P is the pressure drop and P is the upstream side while a 'is a constant.

In one embodiment, where the throttle means comprise at least one valve body cooperating with a stationary valve seat, the valve body may be associated with a compensating piston which is influenced by the pressure in the bypass line before or after the throttle fit. This adds a virtually constant force effect to the valve body, namely the atmospheric pressure acting on the outside of the equalizer piston, whereby the above formula is changed to ΔΡ = a'P + 3 ', where 3' is a constant different from zero.

In addition, the movable member of the throttle member, which is controlled by the pressures in the bypass line before and after the throttle passage, may be loaded by an elastic member which acts to increase the flow cross-section of the throttle passage. In this embodiment, the throttle passage is kept open when the pressures before and after the throttle passage are the same when the engine is at a standstill, which allows the turbine and compressor to be started before the engine is started. In addition, the spring force of the elastic member is included in the constant β ', and by using a means with adjustable spring force, the size of the constant can be varied.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail below with reference to the drawing, in which 1 schematically shows a pressurized diesel engine according to the invention, equipped with a combustion chamber and a single fresh air inlet; FIG. 2 schematically shows a pressurized diesel engine equipped with a combustion chamber and two fresh air approaches, according to an embodiment of the invention, wherein the combustion chamber is fed from a return nozzle injection nozzle; FIG. 3 is a schematic diagram of a pressurized diesel engine equipped with a two-chamber combustion chamber for fresh air, according to an embodiment of the invention, wherein the combustion chamber is fed from a non-return injection nozzle; FIG. 4 is a partial view of a variant of FIG. 2; and FIG. 5 is a graph showing the operation of a motor according to the invention.

In FIG. 1 is shown a diesel engine 101 which is pressurized by a turbocharger assembly 102.

The turbo compressor assembly 102 comprises a compressor 103 which supplies compressed air to the engine through a duct, and a turbine 104 which pulls the compressor 103 through an intermediate shaft 30 105 and is driven by exhaust gas from the engine 101.

A bypass line 106 allows a direct and permanent passage of fresh air from the compressor 103 to the exhaust gas from the engine. A combustion chamber 107 on the upstream side of the turbine 104 is fed with exhaust gas and with fresh air from the bypass line 106.

6 143518

Variable cross-sectional throttle members 108 are arranged in such a way that they flow through air from the bypass line 106. Between the upstream portion of the bypass 106, i.e. the portion connected 5 to the compressor 103 and the downstream portion of the bypass line, i. the part connected to the turbine 104 through the combustion chamber 107, the throttle means 108 produces a pressure difference ΔΡ, which is a growing function, preferably a linear or substantially linear function, of the pressure prevailing in the upstream part P.

This linear function can be written: Δ P = a'P + 8 '.

In the embodiment shown in FIG. 1 of the invention, the throttle members 108 comprise a valve body 108a which cooperates with a fixed seat 108e in the bypass line 106.

The valve body 108a is mounted on a stem 108b, the other end of which is integral with a compensating piston 108c connected to the bypass line 106 through a bellows 108d.

The diameter of the valve body 108a and the diameter of the piston 108c are sized such that the valve body 108a is balanced by the pressure P on the upstream side and the inside of the piston 108c, by the pressure P - Δ P on the downstream side, and by the atmospheric pressure on the outside of the piston 108c.

Elastic return means, consisting of a spring 109, supplemented, where appropriate, with the elasticity of the deformable bellows 108d, influence the valve body 108a and thereby determine the value of the coefficient 8 'in equation Δ P = a'P + 8'.

In order to vary the coefficient 8 ', there may be control means which enable adjustment of the force exerted by the resilient return means U3518 7 on the valve body 108a. These control means here consist of a screw 110 which changes the tension of the resilient return means. Thereby one can adjust the pressure difference provided by the throttle means 108 and in particular compensate for pressure loss caused by an air filter 111 at the access to the compressor 103 and / or by a silencer 112 at the exit of the turbine 104.

A hydraulic steam means, which is discussed in more detail below, may act on the throttle means 108 to absorb aerodynamic vibrations to which the valve body 108a may be exposed. This damping means is preferably fed from a variable pressure fluid source.

In the following, an embodiment of the invention will be described in which a combustion chamber is fed with fresh air from a primary air supply for introducing fresh air into a combustion zone and from a secondary air supply for introducing fresh air 20 into a mixing zone.

Referring first to FIG. 2 and 3 showing a diesel engine 1 which is pressurized by a turbocharger compressor assembly 2.

The turbo compressor assembly 2 comprises a compressor 3 which supplies compressed air to feed the engine through a conduit 4, and a turbine 5 which draws the compressor 3 through a shaft 6 and is driven by exhaust gas from the engine 1.

An bypass line 7 enables a direct and permanent permanent supply of fresh air from the compressor 3 to the exhaust gas from the engine.

On the upstream side of the turbine 5 there is a combustion chamber 8 which is fed with exhaust gas through a duct 9 and with fresh air from the bypass 7.

This combustion chamber 8 is further fed with fuel from an injection nozzle 10 which is fed from a reservoir 12 by means of a pump 11.

The supply of exhaust gas and fresh air to this combustion chamber 8 can be effected through a primary air supply 13 for introducing fresh air into a combustion zone 14, through an exhaust gas access 15 for introducing exhaust gas into a mixing zone 16 located on the downstream side of the combustion zone. 14, and through a secondary air supply 17 10 for supplying fresh air off said mixing zone 16.

The primary air supply 13 takes place along a central duct 18 which is coaxial with the combustion chamber 8, the exhaust gas inlet is constituted by a first, 15 annular duct 19 surrounding the middle duct 18, and finally the secondary air supply 17 takes place on a secondary annular duct 20 which surrounds the first annular duct 19.

An annular throttle passage 21 of variable 20 cross-sectional area is flowed through the secondary air and produces between the upstream portion of the bypass 7 connected to the compressor 3 and the downstream portion of the conduit 7 connected to the combustion chamber 8, a pressure drop ΔΡ which varies with the pressure P of 25 preferably according to the aforementioned linear function ΔΡ = α'Ρ + β '. A primary air flow passage 22 has variable flow cross-section, which depends partly on the pressure drop Δ P and partly on the pressure P -ΔΡ, which is explained in more detail below.

The elements providing the variable flow passage 22 are coupled to a regulator 23 for the fuel injected into the combustion chamber 8 in such a way as to maintain a relationship between the consumption of primary air and fuel which ensures good combustion stability, ie a ratio as close as possible to the stoichiometric ratio.

The fresh air 5 withdrawn from the circulation line thus divides as follows:

Primary air passes through passage 22 and primary air access 13 to the combustion zone 14 of the combustion chamber 8, and secondary air passes through the throttle passage 21 and secondary air access 10 17 to the mixing zone 16 of the combustion chamber 8.

The amount of air passing through the bypass line 7 varies in a ratio of 1:10 depending on whether the engine is operating at full speed (the combustion chamber in idle state) or the engine is operating at idle 15 (the combustion chamber maximum loaded).

In contrast, the ratio of fuel consumption needed to ensure the operation of the combustion chamber 8 to allow operation of the turbo compressor assembly 2 at engine start 20 is the fuel consumption sufficient to maintain the function of the combustion chamber 8 at idle. : 1st

The combustion chamber stability is optimal if the primary air flow is only slightly larger than the amount of air corresponding to stoichiometric combustion.

Thus, there must be a certain relationship between the flow cross-section S for the primary air flow.

P

and the flow cross-section Sg of the secondary air.

If Δ P denotes the pressure difference between the two sides of the throttle passage and P the pressure prevailing in the upstream portion of the bypass line, as mentioned, the growing linear function connecting 1435 18 10 Δ Ρ and Ρ can be written as follows: Δ P = α P + ¾ where α and B are two coefficients.

Furthermore, this pressure difference is proportional to the density m of the fresh air and the square of the velocity V: Δ P = k m V2, since k in the first approximation is constant.

One can then deduce from these two equations the greatest travel of the velocity V: v - k m

The sum of the cross sections S and S is connected so as to the total air consumption Q, ie. the total flow of fresh air in the circulation line by the following equation: p + phase m V 'where S is a function of P which can be written as

f (p). P

Inserting the expression for V gives the following equation: sp + Ss - o [_ £ <«* + e> _ ~% ·

In these circumstances, the primary air consumption · m · v depends only on the pressure P

according to Equation 25 Qp = f (P) (o P + 3) ~ h '

The secondary air consumption is always equal to the difference between the total consumption passed through the bypass line and the primary air consumption Qp 11 143518 Q = Q - Q. s p

Under these circumstances, and to determine the consumption of primary air and secondary air, it is sufficient to affect one flow cross section, e.g. the cross section S, the other being

P

makes themselves the difference.

The control function used, on the one hand, to control the cross section of the primary air, and secondly to control 10 of the pressure P - Δ P prevailing in the downstream portion of the bypass duct 7 can be selected with respect to the combustion chamber's interaction with the unit consisting of engine and turbo compressor. This function will be returned in more detail later, after describing two forms of the invention in the following, the first feeding the combustion chamber from a return nozzle injection nozzle; 2, the second with feeding of the combustion chamber from an injection nozzle without return flow; FIG. Third

20 According to an embodiment of the invention, which is particularly simple from a structural point of view and which can be carried out in two different ways, shown respectively in FIG. 2 and 3, the throttle passageway 21 is delimited by a movable member formed as a cylinder 25 which externally carries a throttle member 25 cooperating with a fixed seat 26. The flow passage 22 is constituted by one or more apertures 27 in the cylinder 24 and thus cooperating openings 28a in the skirt 28b, which align to a greater or lesser degree with the openings 27. The slider forms a piston whose one side is exposed to the pressure of the primary air and whose other side is exposed to a back pressure Ρβ and the effect of a spring 29. The slide 28 is connected to the fuel consumption control means 23.

1435 18 12

The back pressure Pc on the slider 28 may be equal to the atmospheric pressure, but in certain cases, in order to offset the control level, a back pressure Pc greater than the atmospheric pressure can be chosen. Such counterpressure can be provided in a control chamber 30 in connection with the left end surface of the slider 28 and in connection with atmospheric pressure through a throttle opening 31. The chamber 30 can be pressurized through a flexible duct 32 and when the air 10 flowing out of the chamber 30 through the throttle opening 31, an overpressure in the chamber 30 produces the back pressure P.

For this purpose, it is particularly advantageous to connect the flexible duct 32 to a location of the engine installation from which compressed and cooled fresh air can be extracted. Thus, between the motor 1 and an intake cooler R, a branch line 52 can be connected which opens into the flexible duct 32 and contains a regulating needle valve 53 which allows the counter pressure Pc to be adjusted to a value between the atmospheric pressure and the exhaust pressure P.

A control spring 33 acting on the left end of the cylinder 24 enables the regulation of the parameter β in the linear function ΔΡ = α P + β, 25 which indicates the pressure drop across the throttle passage 21. The force from the control spring 33 can be adjusted by a movable stop 34 , against which the spring 33 supports.

Since 30 aerodynamic vibrations can occur in the throttle passage 21, it is advantageous to allow a hydraulic damping member to act on the moving part 24 of the throttle passage, as shown in FIG. 4, wherein the same reference numerals indicate the same means as in FIG. 2. The hydraulic damping means 63 is fed from a variable pressure fluid source 64. The pressure from this source 13 replaces the action of the spring and the pressure variation replaces the effect of the movable stop.

The fuel consumption control means 23 is shown in two embodiments, respectively 5. 2 and 3.

In FIG. 2, the pump 11 feeds the injection nozzle 10 at constant pressure through a supply duct 35, and the excess fuel not injected into the combustion chamber passes through a return line 10 36 which opens through a flexible duct 37 into the regulator 23.

The member 23 comprises a movable member 38 having a tapered needle 68 which is connected through a spindle 69 to the slides 28 of the passage 22, the adjustment effect being achieved by the needle being inserted shorter or further into an opening 39 thereby changing the opening of the opening. flow cross-section.

The fuel is passed through flexible duct 37 into an inlet chamber 40 and passes therefrom 20 through the adjustable opening 39 into a chamber 41, from which it is returned to reservoir 12 through duct 43 through a flexible duct 42.

In FIG. 2, an increase in pressure on the right side of the slider 28 causes a displacement 25 of the slider to the left with the result that the flow cross-section of the passage 22 is reduced, which causes a reduction in the consumption of primary air and the moving means 38 with the needle 68 in the fuel consumption regulating means 23 is shifted to the left, increasing the flow cross-section of the variable flow opening 39 so that the amount of fuel in the return line 36 is increased, thereby reducing the amount of fuel injected into the combustion chamber.

143518 As the pressure on the slider 28 decreases, the reverse occurs.

In FIG. 3, the same reference numerals indicate the same means as in FIG. 2, but the combustion chamber 8 is fed 5 with fuel through an injection nozzle 10a without return. The injection nozzle 10a is fed by a pump 11a from a reservoir 12 through a fuel consumption regulator 23 and a supply channel 35a.

The regulating member 23 comprises a movable member 38a connected through the spindle 69a to the slide 28. The regulating effect is achieved by the needle 68a being able to pass shorter or further into the opening 39a, thereby varying the flow cross-section of the opening.

The fuel is passed through a flexible channel 37a to an inlet chamber 40a, after which it is swirled through passage through the variable flow opening 39a, before flowing into a chamber 41a, from which 20 it flows out through a flexible channel 42a and at high pressure to the injection nozzle 10a. through a channel 4 3a.

In order to maintain a constant pressure difference between the two sides of the adjustable flow opening 39a, a regulator 44 consists of a cylinder 45 in which a free piston 46 slides or covers an opening 47 in the wall. of the cylinder 45. The piston defines a chamber 48 located at the same side as the opening 47 and communicates with the access chamber 40a in the fuel consumption regulating means 23, and a chamber 49 located on the other side of the opening 47 and is in connection with the chamber 41a of the regulating means 23.

Thus, the free piston 46 is affected by the pressure difference prevailing between the two chambers 40a and 41a, as well as by a spring 50 acting in the opposite direction of this pressure difference.

The aperture 47 is in connection with an outlet duct 54 which opens into the fuel reservoir 12.

In FIG. 3, it is seen that increasing the pressure exerted on the right side of the slider 28 will cause a displacement of the slider 28 to the left, 10 which results, in part, in reducing the flow cross-section of the passage 22, which reduces the consumption of primary air and in part. moving the movable member 38a with the needle 68a of the fuel consumption control means 23 to the left and decreases the flow cross-section of the variable flow opening 39a so that the amount of fuel through the feed duct 35a is reduced.

As the pressure exerted on the slider 28 decreases, the reverse occurs.

In the controller 44, the free piston 46 covers the opening 47 more or less. The displacement of the free piston 46 is very small in that the force exerted by the spring 50 on the free piston 46, 25 is practically constant, and for this reason the pressure difference between the chamber 40a and the chamber 41a is practically constant and independent of it. pressure prevailing in the combustion chamber 8 and of the amount of fuel injected.

The magnitude of this pressure difference is adjusted by adjusting the spring 50, which abuts against an adjustable stop 51.

Thus, the amount of fuel passing through the variable flow opening 39a depends solely on the flow cross-section and, consequently, solely on the charge pressure which determines the position of the slider 28. When one or the other of the respectively in FIG. 2 and 4 and in FIG.

3, by influencing the geometry of the passage 22 and the spring 29 influencing the slider 28, a control function can be selected between the cross section and the pressure P - Δ P or the difference between the pressure P - Δ P and the counter pressure P prevailing in the control chamber. 30th

10 For each value of the flow cross-section

Sp corresponds to a value for the primary air consumption Q, corresponding to a fuel quantity q to be introduced into the combustion chamber, and this fuel quantity is determined by the geometry of the variable flow opening.

Taking into account the function of the engine, the following has been achieved:

Within the limits of the combustion chamber's ability to regulate the fuel quantity q in order to prevent the charge pressure from falling below a certain limit, to enable the start of the turbocharger compressor before the engine, and to enable the operation of the combustion chamber at idle with the possibility of a rapid rise to full power without the risk of extinguishing.

25 The fuel quantity q to be introduced into the combustion chamber is hereby dependent on the downstream side pressure P - Δ P or the pressure difference between the downstream side pressure P - Δ P and the backpressure P prevailing in the control chamber 30. This function is illustrated, for example, by the curve in FIG. 5, where, as an abscissa, the relative charge pressure P, expressed in bar, and as ordinate the fuel consumption q in the combustion chamber is plotted.

When there is no back pressure, ie. that the pressure 35 in the control chamber 30 is equal to the atmospheric pressure, the working point of the combustion chamber is on the curve.

If this idle stabilizes at point K, it will pass downward to point C when the engine load increases to approx. 20% of the maximum load, and in addition, the working point shifts between C and D. The combustion chamber is then idle.

The introduction of a back pressure into the control chamber 30 causes the curve to be shifted to higher 10 pressures corresponding to an increase of the predetermined limit value B for the charge pressure.

This simple displacement of the control region by pneumatic path can be accomplished to achieve a power increase at low rpm. It is also possible to utilize the displacement of the control range to accelerate the temperature rise of the engine at idle when the combustion chamber is fully loaded, provided that there are heat exchange means between the hot air from the compressor and the engine's cooling medium.

The introduction of a backpressure, possibly right up to the charge pressure, allows for the offset of the control area to compensate for decreasing atmospheric pressure. Thus, when the atmospheric pressure is reduced, the counterpressure can be given a value corresponding to the charge pressure, which causes a complete opening of the control means and that the combustion chamber is fed at full force (the primary air consumption and the fuel consumption reach their maximum values).

Thus, by means of the invention, both the fuel quantity injected into the combustion chamber 8 and the primary air quantity can be controlled by acting on the geometry of the passage 22 with the openings 27 and 28a and on the tarring and possibly the regulation of the springs 29 and 50. thus say a mixture of air and fuel in the combustion zone

Claims (3)

143518 14 with appropriate ratios in the vicinity of the stoichiometric in order to achieve good stability of the combustion chamber 8 within all engine speeds. An internal combustion engine, in particular a diesel engine, with a turbocharger driven from the engine, which is designed to supply charging air to the engine, and an inlet line between the outlet of the compressor and the turbine, which inlet during operation of the engine 10 may be permanently open but containing throttle means with at least one throttle passage, whose flow cross-section is variable to produce a pressure difference between the outlet of the compressor and the turbine approach, characterized in that the throttle means (108; 25, 26; 24, 28) are controlled essentially solely by the pressures before and after the throttle passage and in such a way that an increase in the pressure after the throttle passage leads to a decrease in the flow cross-section and an increase 20 of the pressure before the throttle passage causes an increase in the flow cross-section and that the pressure difference induced by the throttle means changes in the same direction. such as the pressure in the bypass line (106, 7) before the throttle passage. Engine according to claim 1, characterized in that the throttle means comprise a movable guide member with surfaces which is influenced by the pressure prevailing in the orifice line before and after the throttle passage, and that the effective area of the faces of the guide member, which is affected by the pressure before the throttle passage is less than the effective area of the faces of the control member which is affected by the pressure after the throttle passage. Engine according to any one of claims 1-2, and