GB2079370A - Multi-cylinder reciprocating engine with resonance charging - Google Patents

Abstract

At most four cylinders (1, 2, 3; 4, 5, 6) having successive valve control times which at most slightly overlap are each connected by means of pipes (10) to one of two resonance volumes (11, 12) The resonance volumes are inter- connected by a resonance passage (13) and form in conjunction therewith a charging system which is tuned to resonance, The fresh air infeed to such system is accomplished by means of a pipe (14) which is constructed such that its natural vibration frequency is not equal to the resonance vibration frequency of the tuned system. One of the resonance volumes (32), Figures 4 and 5 (not shown), may be formed by a charge air cooler. <IMAGE>

Description

SPECIFICATION Multi-cylinder reciprocating engine with resonance charging Background of the invention The present invention relates to a new and improved construction of a multi-cylinder reciprocating engine with resonance charging.

Under the expression "resonance charging" there is understood in conjunction with multi-cylinder reciprocating engines arrangements located at the inlet side and containing a fresh gas-vibration system which is tuned to resonance. Such vibration system encompasses resonance pipes and, if desired, resonance containers. Such form a vibration system having a well defined natural or sympathetic vibration frequency. The principle of resonance charging can be used perse or in conjunction with turbocharging gs a so-called combined charging. If the vibratable arrangement is connected between the turbo-charger or air infeed pipe and cylinder and if it is energised during movement of the pistons during operation of the machine during the successive suction intervals at a frequency which approximates such natural vibration frequency, then there arises resonance.This resonance produces augmented pressure vibrations by means of which the degree of filling of the engine cylinders is appreciably improved throughout a desired range of rotational speeds of the engine in comparison to internal combustion engines working without such resonance charging. The improved filling of the engine cylinders is attributable to the momentary excess pressure conditions which prevail at the time of closing of the inlet valves and governed by the vibration phenomenon which arises during resonance charging. Further details concerning the above have been disclosed in MTZ Motortechnische Zeitschrift Number 39 (1978), pages 447 to 451.

In arrangements of the aforementioned type located at the inlet side of the engine and known to those skilled in this technology each engine cylinder is connected by means of a long and thin suction pipe with a compensation container into which open all of these equal length suction pipes. The compensation container flow communicates by means of a connection line with the turbocharger or the air infeed pipe following the air filter. This arrangement affords a dynamic charging with superimposed resonance region and the suction pipes function as a resonance pipe.

These state-of-the-art arrangements are afflicted with the decisive drawback that at high engine rotational speeds there results an increased consumption of fuel by virtue of the throttling produced by the long and thin resonance pipes. Furthermore, an additional shortcoming of such prior art arrangements is constituted by their considerable space requirements and complicated constructional expenditure.

In German petty Patent No. 1,723,349 there is disclosed a similar inlet-side arrangement at an engine utilising turbocharging and increased charging by fresh air vibrations at lower engine rotational speeds. With this system design too, at most three cylinders having adequate ignition intervals open in each case into a container from which leads to the turbocharger a pipe which is effective as a resonance pipe. By providing a particularly long design of the resonance pipes it is intended to place in a desired coordination or tuning the duration of the resonance vibrations of the fresh gas infeed system with the suction duration of the related cylinder at lower engine rotational speeds.

An inlet-side arrangement which deviates from the foregoing system designs has been disclosed in German Patent No. 1,935,155 and German Patent Publication No. 2,245,732. The inlet openings of the cylinder of in each case a group of at most four cylinders, the suction intervals of which do not or only slightly overlap, are connected by means of relatively short suction channels with a resonance container. Between each of these resonance containers and a compensation container there are arranged resonance pipes. The compensation container is connected by means of a connection pipe with the pressure side of the turbocharger.A prerequisite of the explained design is that the volume of each resonance container be greater than one half, but smaller than the ten-fold of the entire working volume of the cylinder or cylinders connected with the resonance container, and further, that the length of each resonance pipe be greater than the eight-fold of the diameter of a circle, the area of which is equal to the throughflow crosssectional area of the related resonance pipe.

Also both of the last-mentioned prior art arrangements are extremely complicated in construction due to the required multiplicity of pipes and containers and necessitate a great amount of space which is anyway limited in vehicles.

Summary of the invention Therefore, with the foregoing in mind it is desirable to provide a new and improved construction of multi-cylinder reciprocating engine with resonance charging which is not afflicted with the aforementioned drawbacks and limitations of the prior art proposals.

Another and more specific desirable feature aims at providing a reciprocating engine of the previously mentioned type which, while maintaining the advantages of the heretofore known constructions, realises such advantages with an appreciably reduced constructional expenditure and a likewise appreciably reduced requirement in space and which can be easily tuned.

The invention proceeds from a multi-cylinder reciprocating engine working with resonance charging, wherein there is accomplished utilisation of the vibrations of the fresh gas at the inlet line by means of a multiple system composed of resonance containers and tuned to resonance. At most four cylinders working with successive valve control times which at most slightly overlap are connected with a resonance container. In particular, in accordance with important aspects of the present development a single resonance pipe directly connects in each case two resonance containers. Into one of the resonance containers there opens a fresh gas infeed pipe, whose natural vibration frequency is outside of the resonance vibration frequency of the resonance pipe-resonance container-vibration system.

The constructional simplification and the saving in space which is obtained with such arrangement, in contrast to the previously mentioned prior art constructions, is predominantly predicated upon the fact that the compensation container and/or at least one resonance pipe is dispensed with. In contrast to an arrangement, such as for instance disclosed in the previously mentioned German Patent No. 1,935,155 and German Patent Publication No. 2,245,732, wherein for a six-cylinder engine there are needed apart from two resonance containers in each case for three cylinders also two resonance pipes and a compensation container, the system design according to the present development does not require the use of any compensation or equilisation container and only a single resonance pipe for interconnecting both of the resonance containers.

A particularly compact and material-saving design is realised according to an advantageous embodiment in that a partition or separation wall within a fresh gas collector subdivides such into two resonance containers. The resonance pipe which interconnects the two resonance containers is integrated in the form of a channel in such collector. This channel is formed between a wall which piercingly extends through the partition wall and is directed along the one housing wall of the collector and such housing wall.

The simple design which is proposed herein additionally renders possible, with the use of simple and correspondingly economical means. eliminating a further drawback of the heretofore known constructions which is predicated upon their rigidity. By virtue of the fact that such prior art constructions are only capable of accomplishing their desired action in a limited range they are not particularly suitable for use with engines having a wide operating rotational speed range. Although it was known that it would be possible to eliminate this drawback by providing an adjustability of the vibration system, the realisation of this proposal was not heretofore possible and seemingly failed because of the numerous parts of the prior art vibration systems and the there-with associated structural complications.

Yet, with an internal combustion engine designed according to the teachings of the present development such can be realised, according to a further advantageous design, in that the active or effective length of the single resonance pipe which influences the resonance vibration frequency of the vibration system can be altered or changed.

For instance, for this purpose the resonance pipe can be provided with at least one opening which, for instance, is maintained in a closed condition by a valve or equivalent closure element. Upon actuation of the valve the related opening is freed and the active or effective length of the resonance pipe is correspondingly changed.

When using the concepts of the present development in conjunction with multi-cylinder reciprocating engines working with turbocharging pressure fluctuations are transmitted from the resonance charging system to the compressor of the turbocharger and therefore can excite the same so as to "surge".

This phenomenon can be relatively easily eliminated according to a further advantageous design of the invention when used with exhaust gas turbocharged engines by designing the fresh gasinfeed system such that the natural vibration frequency of such fresh gas-infeed system --composed of the fresh gas-infeed pipe, the resonance container into which opens such fresh gas-infeed pipe, the compressor of the turbo-charger, the air infeed pipe leading thereto, an air filter and its infeed pipe-- is smaller than the resonance vibration frequency of the resonance pipe-resonance container-vibration system.

When utilising the principles in conjunction with engines working with turbocharging and boost or charging air cooling there is realised an advantageous design in that one of the resonance containers is constructed as a boost or charging air cooler.

Brief description ofthe drawings The invention will be better understood and feature other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: Figure 1 schematically illustrates in sectional view a six-cylinder diesel engine working with combined charging; Figure2 schematically illustrates a modified embodiment having a regulatable resonance vibration frequency; Figure 3 schematically illustrates a further embodiment for turbocharged six-cylinder engines; Figure 4 schematically illustrates an embodiment forturbocharged six-cylinder engines working with boost or charging air cooling; and Figure 5 schematically illustrates an embodiment for a turbocharged four-cylinder engine with charging or boost air cooling.

Detailed description of the preferred embodiments Describing now the drawings, in Figure 1 there is schematically illustrated a six-cylinder four-cycle engine. The cylinders 1 to 6 arranged in the engine block 7 each possess a not particularly illustrated but conventional inlet valve and outlet valve. The outlet valves are connected by means of outlet channels 8 with a common exhaust gas pipe 9. A respective short suction connection pipe 10 leads to the inlet valve of each cylinder 1 from the inlet side.

Corresponding to the conventional mode of operation of such engine the arrangement of the alternately successive valve control times of the cylinders 1, 3, 2 on the one hand and the cylinders 5, 6,4 on the other hand, is such that the suction intervals or periods both of the cylinders of the group containing the cylinders 1, 2 and 3 and also the cylinders of the group containing the cylinders 4,5 and 6 either do not overlap at all or at most only inconsequentially overlap. The suction connection pipes 10 of the group of cylinders 1,2 and 3 open into a common resonance container 11 and in corresponding manner the suction pipes 10 of the group of cylinders 4, 5 and 6 open into a second resonance container 12 which is arranged coaxially with respect to the first resonance container 11.Connected with both of the resonance containers 11 and 12 is a resonance pipe 13. This resonance pipe 13, in contrast to the heretofore known constructions, directly interconnects in a bypass-like fashion both of the resonance containers 11 and 12 with one another. The fresh gas infeed to the illustrated engine is accomplished by means of a fresh gas infeed pipe or line 14 which, equally in contrast to the heretofore known prior art constructions, opens into one of both resonance containers, in this case the resonance container 12.

This fresh gas infeed line 14 is connected in conventional manner with the outlet or exit side of a turbocharger 15. Arranged at a shaft which is common to a compressor 16 oftheturbocharger 15 is a turbine 17 at which merges the exhaust gas pipe 9.

Continuing, the exhaust gases of the engine move through the exhaust gas pipe 9 into the turbine 17, drive such turbine and then are aspirated into the surroundings. The compressor 16 which is driven by the turbine 17 expresses the air which is sucked-up from the surroundings through the fresh gas infeed pipe or line 14 into the resonance container 12, from which a part arrives by means of the resonance pipe 13 at the second resonance container 11. The fresh gas flows out of both of the resonance containers 11 and 12 into the cylinders. The periodic suction action prevailing at the cylinders then excites the air columns in the vibration system so that such vibrate.

The vibration system is composed of both of the resonance containers 11 and 12 and the resonance pipe 13. To ensure that the air flow in the fresh air infeed pipe or line 14 does not disturb the resonance vibrations of such vibration system, its dimensions must be designed such that its natural vibration frequency in any event is outside of the resonance vibration frequency of the vibration system, constituted by the resonance containers 11, 12 and the resonance pipe 13.

The described inlet-side arrangement as shown in Figure 1 therefore enables, as will be readily apparent, an appreciable simplification of the constructional expenditure with almost identical dynamic charging action. This is so because the air infeed pipe 14 leading from the turbocharger 15 merges, without interposing a compensation vessel, at one of the resonance containers, here the resonance container 12, and there is only required a resonance pipe 13 which simultaneously establishes the flow connection to the second resonance container 11. By virtue of the alternate suction action of both cylinder groups at their related resonance container there is excited the desired gas vibrations.

When employing the concepts of the invention in conjunction with a reciprocating engine working without any turbocharging then there are dispensed with the parts 15, 16 and 17. With such arrangement the exhaust gases of the engine are directly expelled or by means of a muffler into the surroundings through the exhaust gas pipe 9 and the fresh air infed to the pipe 14 is directly infed thereto or through an airfilter into such pipe 14. The remaining construction of the system remains unaltered with respect to that discussed above in detail in conjunction with the foregoing description of Figure 1.

With the modified embodiment shown in Figure 3, depicting a six-cylinder four-cycle engine with turbocharging, an air infeed pipe or line 18 at which there is connected an air filter 19 is arranged forwardly of the compressor 16. Reference character 19a represents the suction line leading to the filter 19. The pneumatic fresh gas infeed system, which is arranged upstream or forwardly of the resonance pipe-resonance container-vibration system 13, 12, 11, encompasses the pipe section 19a, the filter 19, the compressor 16, the pipe 14 and the resonance container 12. The adaptation or tuning is undertaken such that the natural vibration frequency of this fresh gas infeed system is below the lowermost natural vibration frequency of the resonance system.During the determination of the natural vibration frequency of the pneumatic fresh gas infeed system 12, 14,16, 18, 19 and 19a the volume content of the resonance container 12 constitutes the pneumatic spring, whereas the second resonance container 11 is decoupled by the thus higher natural vibration frequency of the resonance pipe-resonance container-vibration system.

Figures 4 and 5 portray the use of the concepts of the invention in conjunction with turbocharged engines working with charging or boost air cooling.

In particular, Figure 4 schematically illustrates a proposal for a six-cylinder four-cycle engine, whose vibration system is augmented by the resonance container 32, designed as a boost or charging air cooler, and the connection line or conduit 33. The system, composed of the resonance containers 32 and 12 and the connection line or pipe 33, has the same resonance frequency as the system composed of the containers 12 and 11 as well as the connection pipe or line 13. In this case the fresh air is again infed to the system through the line 14 into the container 32. Th remaining construction and the mode of operation remains unaltered in relation to the system design of Figures 1 and 3 and the description of their operation as disclosed in detail heretofore.

Figure 5 illustrates a schematic embodiment for a turbocharged air-cooled four-cylinder four-cycle engine.

In accordance with the mode of operation of such engine the sequence of the valve control times is such that at most there prevails a slight overlapping.

The suction connection pipes 10 of the engine open into a common resonance container 12. A resonance pipe 33 interconnects the resonance containers 12 and 32, wherein the resonance container 32 is here designed as a boost or charging air cooler. The fresh air infeed, also in this case, is accomplished by means of the line or pipe 14 into the resonance container 32. The remaining construction and mode of operation is as described previously in conjunction with the embodiment of Figures 1,3 and 4.

The structural simplification of the described arrangements, in contrast to heretofore known prior art arrangements used for the same purpose, now enables with very simple means altering the vibration frequency of the vibration system, and thus, expanding upon the rotational speed range of the engine with maximum charging effect.

Such an arrangement with controllable active or effective length of the resonance pipe now will be described in detail based upon the illustration of Figure 2, which additionally portrays a particularly compact design of the vibration system. The construction of the vibration system with the embodiment of Figure 2 differs from that of Figure 1 in that, in this case, instead of using two physically separated resonance containers and a resonance pipe which interconnects such resonance containers in a by-pass like fashion, here there is employed a single container 20 which can be constituted by the fresh gas collector pipe of the engine. Such is divided by a intermediate separation or partition wall 21 into two chambers 22 and 23.Reference character 24 designates the inlet channels of the cylinders of the illustrate six-cylinder engine which again are divided into two groups each having three cylinders. The cylinder groups open in groups into a respective one of both chambers 22 and 23. These chambers or compartments 22 and 23 thus correspond to both of the resonance containers 11 and 12 of the embodiment disclosed with reference to Figure 1.

The resonance pipe 13 of the embodiment of Figure 1, in the embodiment of Figure 2, corresponds to a channel 25 which is formed within the container 20 between a wall 26 interrupting the partition or separation wall 21 and the neighbouring wall portions of the container 20. The fresh gas infeed pipe has been here designated by reference character 29 and opens into the chamber 22. Apart from the described constructional design the arrangement of Figure 2 therefore completely corresponds to that according to Figure 1, with the vibration system composed of both of the resonance chambers 22 and 23 which are interconnected by a single resonance channel 25.

The wall 26 bounding the channel 25 possesses a lateral opening 27 at which there is formed a valve 30, for instance a charging pressure-dependent valve. The valve 30 constitutes a valve seatforthe valve body 28. By actuating the valve 30 and thus by freeing or closing the opening 27 in the channel 25 it is possible to alter the active length thereof, which affects the resonance vibration frequency of the vibration system, by the length of the channel section 31.

Of course also in this case there is to be taken care to ensure that the air infeed pipe 29 is structured in a manner such that this air infeed pipe 29, to the extent possible, does not cause any vibration effects at the connected resonance container.

Claims (8)

1. A multi-cylinder reciprocating engine working with resonance charging, wherein utilisation of the vibrations of the fresh gas in an inlet line is accomplished by means of a multiple system tuned to resonance and composed of resonance pipes and resonance containers, there being connected at most four cylinders to a resonance container and having successive, at most few overlapping valve control times, and comprises: a single resonance pipe which in each case directly interconnects two resonance containers with one another; a fresh gas infeed pipe opening into one of the resonance containers; and said fresh gas infeed pipe being designed such that its natural vibration frequency is outside of the resonance vibration frequency of the vibration system composed of the resonance pipe and resonance containers.

2. An engine as defined in claim 1, further including: a fresh gas collector; a partition wall provided for the fresh gas collector for subdividing said fresh gas collector into two containers defining said resonance containers; said resonance pipe interconnecting said two resonance containers being integrated in the form of a channel in said collector; said collector having a housing wall; said channel being formed by a wall which piercingly extends through the partition wall and said housing wall; and said channel wall extending along said housing wall in spaced relationship therefrom.

3. An engine as defined in claim 2, wherein: the resonance pipe has an active length which influences the resonance vibration frequency of the vibration system; and said active length of said resonance pipe being structured to be changeable.

4. An engine as defined in claim 1, wherein: the resonance pipe has an active length which influences the resonance vibration frequency of the vibration system; and said active length of said resonance pipe being structured to be changeable.

5. An engine as defined in claim 4, wherein: said resonance pipe is provided with at least one opening; and valve means for selectively closing and freeing said opening, in order to thereby change said active length of said resonance pipe.

6. An engine as defined in claim 1, particularly for use with exhaust gas-turbocharged engines, further including: a fresh gas infeed system composed of said fresh gas infeed pipe, said one resonance container into which opens said fresh gas infeed pipe, a compressor of a turbocharger, an air infeed pipe leading to said compressor of the turbocharger, an air filter and an infeed pipe leading to the air filter; and the natural vibration frequency of said fresh gas infeed system being smaller than the resonance vibration frequency of the resonance pipe-resonance container-vibration system.

7. An engine as defined in claim 6, particularly for use in turbocharged, charging air cooled engines, wherein: one of the resonance containers is structured as a charging air cooler.

8. A multi-cylinder reciprocating engine substan tially as any described herein with reference to the accompanying drawings.