DE2834198B2 - Intake pipe heater for a carburetor engine - Google Patents

Description

The invention relates to a suction pipe heating device for a carburetor engine in the preamble of Claim 1 defined genus.

Such Saugrohrheizvorrichtugen serve the To improve mixture preparation in carburettor engines and thus both cold start and warm-up of the Motor as well as the load acceptance of the motor. This is done between the carburetor and Combustion chamber (cylinder) of the engine arranged intake manifold with the exhaust gases from the engine is heated there in heated state fuel and air mix much better. For an optimal mixture preparation, which also for the content of nitrogen oxides in the exhaust gas It is decisive, depending on the load output of the engine and temperature, the heat supply to the Regulate suction pipe.

In a known Saugrohrheizvorrichtung of the type mentioned (US-PS 15 07 315) is the Boiler room in the manner of a bypass below the suction pipe and is via its inlet port with a Exhaust manifold connected to which the exhaust pipes of the individual cylinders of the engine are connected servomotor operated first heating flap and in the collecting line at a distance from the entrance of the A second heating flap, which is also actuated by a servomotor, is arranged in the boiler room. Each heating flap is located via an actuating gear with a vacuum piston connected, which via a vacuum line with a can be connected to the vacuum chamber connected to the suction pipe via a valve device controlled by a bimetal strip. With increasing warming of the suction tube bulges the bimetallic strip and

so the valve device opens. The pistons are then actuated by the negative pressure in such a way that the first The heating flap closes increasingly and the second heating flap opens increasingly part of the exhaust gas quantity that occurs when the intake manifold is cold flows through the boiler room in this, whereby the The boiler room is less heated. The second flap is preferably between the mouth of the the exhaust pipe coming from the third and fourth cylinder of the engine is arranged in the manifold, but can also be provided at the outlet of the collecting line, namely in the outflow direction before the exhaust gases flowing through the boiler room are returned to the collecting line. This known suction tube heating device is satisfactory regarding the control of the heat supply for a optimal mixture preparation in adaptation to the different operating conditions of the engine, especially when the loads are constantly changing

is not subject to. This is disadvantageous especially the long control times, i.e. the time that passes until a required change in the intake manifold 'temperature is reached. An optimization of the In the case of a cold start, mixture preparation can therefore only take place a long time after the start and with constantly changing Operating states of the engine cannot be reached satisfactorily.

From DE-AS 22 23 655 a suction tube heating device for a carburetor engine is known in which the intake pipe, which consists of two intake ducts, is surrounded by a housing at a distance The housing is flanged on the one hand to the carburetor and on the underside by means of a heat exchanger plate completed, which is one of the two Saugrohrkanä-Ien facing boundary wall of the boiler room The boiler room has a supply and an outlet opening from a housing part are covered with the elbow pipe of the Exhaust system is in connection In this housing part, a heating flap is pivotably arranged, each according to position, the entire amount of exhaust gas or part of it passes through the boiler room The housing surrounding the two intake ducts has two control flaps for preheating the two intake 2s arranged pipe ducts These two control flaps consist of a straight part and an approximately right-angled part and are pivoted depending on the position of the two control flaps the fuel / air mixture flowing out of the carburettor is either over the surface of the Heat exchanger plate or - by bypassing the heat exchanger plate - intermediate positions of the control flaps fed to the suction pipe, in which part of the fuel-air mixture is heated on the heat exchanger plate and another part is fed directly to the suction pipe are also possible.

This known Saugrohrheizvorrichtung shows an improved control behavior with respect to the fast Adaptation of the heat supply to the fuel-air mixture, especially when the engine is in different operating states. The tax mecbanism with a total of a heating flap to regulate the amount of exhaust gas flowing past the heat exchanger plate and two further control flaps for the temperature-dependent division of the fuel-air mixture into one mixed flow sweeping over the heat exchanger plate and one directly over the intake manifold supplied mixture flow is quite expensive, which is reflected both in the production costs and low the susceptibility of the Saugrohrheizvorrichtung against Störtn is increased also because of the mutual dependence of the position of the heating flap and the position of the two control flaps this Saugrohrheizvorrichtung relatively difficult to set and adjust.

From DE-OS 25 50 405 a Saugrohrheizvorrichtung for a carburetor engine is known in which A heating space is provided below the suction pipe, ω of the suction pipe only through a heat-conducting one Partition wall is separated The boiler room, which is open at the bottom, is flanged to an exhaust pipe. in the In the boiler room, a heating flap is pivotably arranged, which essentially forms the lower opening of the boiler room can cover completely or completely release, so that the exhaust gases flowing in the exhaust pipe do not or can flow completely through the room.

To improve the heat transfer between the boiler room and the intake manifold, the two face each other Hermetically shielding partition in the Heizt aum protruding ribs. The heating flap is through an external device, not shown, driven in such a way that the heating flap when starting from cold Opening in the boiler room completely releases, so that almost the entire amount of exhaust gas through the The boiler room flows through, and completely covers the boiler room after the engine has warmed up The heating flap therefore has only two positions depending on whether the engine is cold or warm.

This type of control of the heat supply to the intake manifold is in no way satisfactory for an optimal mixture preparation. Even if you know this Intake manifold heater would improve the heating flap depending on e.g. Intake pipe removed parameters is controlled directly, this does not lead to an essential Improvement of the mixture preparation in adaptation to the different operations? engine status, especially if the engine is constantly changing Operating conditions are also subject to effect here - as in the case of the known one described at the outset Intake manifold heater - especially the long control times disadvantageous. The time that goes by to one Change in the control parameters is converted into a corresponding change in the intake manifold temperature too long to make the necessary quick adjustment even with constantly changing operating conditions of the engine to achieve the heating of the mixture.

The invention is based on the object of providing a suction pipe heating device of the type mentioned at the beginning to create a change in the control parameters in the intake manifold caused by a change in the operating state of the engine immediately and quickly into a corresponding change in the intake manifold temperature and thus in all, also rapidly changing Operating states of the engine, be it cold start. Partial load or full load delivery, ensures an optimal mixture preparation be producible at low cost.

In the case of a suction tube heating device, this task is of the type defined in the preamble of claim 1 solved according to the invention by the Merkmaie in the characterizing part of claim 1

As a result of the measures according to the invention, the suction pipe is heated intensively and over a large area. The geometric design of the boiler room with two separate, spatially extended flat heating chambers significantly improves the heat transfer between the exhaust gas and the intake manifold Simultaneous compact and stocky, space-saving design of the suction tube heating device. the Distribution of the primary heating of the Si «i> large for Available amount of exhaust gas on two separate, but closely arranged Heating chambers, each with a separate - albeit synchronously controlled - heating flap are provided, enables a much faster and finer dosage of the heating of the Suction pipe used amount of exhaust gas than is the case with the known suction heating devices which the entire amount of exhaust gas fed to a single boiler room and only through one only heating flap can be dosed. Overall, changes in the amount of exhaust gas have an effect

synchronous adjustment of the heating flaps to the temperature very quickly in the intake manifold. The remaining delays when changing the control parameters in Intake manifold up to the appropriate adjustment of the intake manifold temperature to these changes are very small amount. The intake manifold temperature can therefore very quickly adapt to the changed operating conditions of the engine be adapted, even with constant load changes and also in the partial load range. In all operating states of the In this way, the optimum mixture preparation can be achieved very quickly in the engine. The fuel consumption sinks. When starting, the optimal intake manifold temperature is reached much faster, which is reflected in a improved cold start behavior of the engine. The synchronous coupling of the heating flaps enables the use of only a single servomotor. This creates the prerequisite that the heating flaps depending on one or more control parameters taken from the intake manifold, such as negative pressure and / or temperature, can be adjusted without this adjustment additional control tolerances occur between the two heating flaps. The suction tube heater according to the invention can be used both with an intake manifold with two intake manifold channels and with one intake manifold a single suction pipe can be used in an equally advantageous manner. In both cases, the Intake manifold ducts - or the intake manifold duct - heated quickly and evenly

Overall, the measures according to the invention result in an inexpensive and compact intake manifold heating unit with high efficiency, which takes up relatively little additional space and is advantageous in Motor vehicles, even in modern so-called. Compact cars, can be used.

Further refinements are the subject of the subclaims.

The invention is described below with reference to an embodiment shown in the drawing. It shows

F i g. 1 shows a cross section of the suction tube heating device,

F i g. 2 shows a section along the line II-II in FIG. 1,

F i g. 3 shows a section along the line IH-IfI in FIG. 1.

F i g. 4 shows a plan view of the actuating segment from direction A in FIG. 1.

The intake manifold heating device for a carburetor engine shown in the figures usually leads to this The intake manifold 10 of the carburetor engine, divided into two channels, consists of two exhaust pipes 11 and 12 are hot Exhaust gases too. The exhaust lines 11 and 12 each have a servomotor-operated heating flap 13 and 14 for Control of the exhaust gas quantities assigned

On the suction pipe 10, two are separated from the suction pipe 10 only by a heat-conducting partition 15 Heating chambers 16 and 17 arranged. The heating chambers 16 and 17 are located at the bottom of the suction pipe 10. One each Heating chamber 16 or 17 is in communication with an exhaust gas line 11 or 12, respectively. The heating chambers 16,17 are each through a transverse wall 18, 19 into two adjacent ones, one after the other from the exhaust gas and in opposite directions flow-through guide channels 20, 21 or 22, 23 divided The heating chambers 16, 17 are geometrical designed in such a way that they extend to below the carburetor stages 24,25,26,27, even below the smallest Carburetor stages 26, 27 extend in the intake manifold 10 (FIG. 2). With carburetor stages are the Openings in the suction pipe 10, drawn in dashed lines in Figure 2, meant. This occurs at part load of the engine Carburetor mixture exclusively through the two small carburetor stages 26, 27, i.e. through the im Diameter of smaller passage openings in the suction pipe 10. At full load, the two become larger Carburetor stages 24.25 switched on, so that carburetor mixture The one not shown here flows into the intake manifold 10 through all four passage openings The carburetor is usually located just above the

ίο suction pipe 10. This configuration of the heating chamber 16, 17 an additional significant advantage is achieved. Since the cold engine is usually in Partial load range works, is through this spatial arrangement and design of the heating chambers 16 and

ii 17 made sure that the suction pipe 10 in the Area of the smallest carburetor stages 26, 27 is heated and thus also here optimal temperatures for the Mixture preparation prevail. A significant improvement in the cold start behavior of the engine will be thus brought about. Suction pipe 10 and heating chambers 16 and 17 are part of a common housing 28 surrounded, to which the two exhaust lines 11 and 12 are connected.

A heating flap 13 or 14 is arranged upstream of each heating chamber 16 or 17. The heating flaps 13 and 14 are Coupled with one another in such a way that a synchronous adjustment of the two heating flaps 13, 14 is ensured. This means that the adjustment of a heating flap 13 is a simultaneous and similar adjustment of the causes other heating flap 14 and vice versa. In the suction pipe heating device described here are the Exhaust pipes 11,12 from the exhaust manifolds 30,31 formed and the heating flaps 13, 14 near the connection points 32, 33 of housing 28 and Exhaust manifolds 30, 31 arranged in the exhaust manifolds 30, 31. At the two connection points 32 and 33 between housing 28 and exhaust manifolds 30 and 31 are seals 34 and 35, respectively intended.

The heating flaps 13, 14 are each rigid with a pivotably mounted adjusting shaft 36 and 37, respectively tied together. The adjusting shafts 36, 37 are connected to one another via a temperature-resistant elastic intermediate member 29 Coupled in a rotationally fixed manner In the suction pipe heating device described here, the intermediate member 29 is as Corrugated pipe 38 is formed, which is firmly connected to the two adjusting shafts 36, 37 of the heating flaps 13, 14, is preferably welded to these. The corrugated pipe 38 allows an elastic, but non-rotatable connection

so are the two adjusting shafts 36 and 37. The adjusting shafts 36 and 37 are each in the walls of the two exhaust manifolds 30.31 stored You step in the storage points 39.40, 41, 42 through the manifold walls. The bearings 39, 40, 41, 42 in the walls of the Exhaust manifolds 30, 31 are conically widened outwards and from the outside by means of the adjusting shafts 36 and 37 axially displaceable, spring-loaded, card-shaped and temperature-resistant sealing elements 43,44,45,46 sealed for this purpose is on each of the actuating shafts 36 and 37, a helical spring 47 and 48, respectively, is provided, which is located on one of the actuating shafts 36 or 37 fixed stop 49 or 50 and supported on a sealing element 43 or 46 The two other sealing elements 44 and 45 on the adjusting shafts 36 and 37 are through these two Helical springs 47 and 48 and in each case a securing element arranged on these sealing elements 44 and 45, respectively 51 or 52 in the conical outward

extended locations 40 and 41 pulled into it.

On one of the control shafts, here on the control shaft 37, A servomotor 53 acts outside the exhaust manifold 30, 31. The servomotor 53 is preferably as Vacuum cell 54 is formed. The vacuum unit 54 is connected to the interior of the suction pipe 10. To adjust the actuating shafts through the vacuum unit 54, the actuating shaft 37 carries outside the Exhaust manifold 31 with the control shaft 37 rigid connected actuating segment 55. On this actuating segment 55 is one of the servomotor 53 or the Vacuum cell 54, actuated control rod 56 articulated in such a way that the end points of the trajectory of the Articulation point 57 when adjusting the heating flaps 13, 14 on one aligned with the control rod axis Straight lines 58 lie (FIG. 4).

A top view of the actuating segment 55 from the direction of arrow A in FIG. 1 is shown in FIG. One of the actuating segments is pulled out here

Final position, while the üiidcic Enuiägc ucs SiciiäcgiTicFi-

tes 55 is shown in phantom. The pivot point 57 is in each of the two end positions of the Adjusting segment 55 so that the axis of the adjusting rod 56 passes through these two end positions. This ensures that when adjusting the Heating flaps 13, 14 do not attack any transverse forces on the actuating shafts 36 and 37 and these in the bearing points 39-42 do not tilt. Such tilting of the adjusting shafts 36 and 37 would be in the above described design and sealing of the bearing points 39-42 result in a displacement of the sealing element .inte 43-46 and thus to a gas leakage of the exhaust manifold 30 and 31 at the Storage locations 39-42 lead. By choosing the articulation point 57 of the adjusting rod 56 on the adjusting segment 55, this is prevented and thus the gas tightness the exhaust manifold 30 and 31 ensured. For connecting the control rod 56 and the control segment

55, the actuating segment 55 has a bore 59 in which engages a pin 60 protruding substantially at right angles from the actuating rod 56 so as to be rotatable. This pin 60 is used in the present Exemplary embodiment formed by the angled end of the adjusting rod 56.

As shown in FIG. 1 and 4, the adjusting segment 55 carries two spaced-apart stop tabs 61 and 62, which together with a stationary stop pin 63 limit the maximum pivoting movement of the adjusting segment 55 in opposite directions. The stop pin 63 and the two stop tabs 61 and 62 are here assigned to one another in such a way that in each case when a stop tab 61 or 62 rests on the stop pin 63 the heating flaps 13 and 14 take their respective end position. The stop pin 63 is preferably in the Wall of an exhaust manifold, here in the exhaust manifold 31, held. The stop pin 63 is like this arranged that he is on the the end points of the trajectory of the articulation point 57 of Stelistange

56 lies on the straight line 58 connecting the actuating segment 55 during the heating flap adjustment (FIG. A).

The mode of operation of the suction pipe heating device according to the invention is as follows:

The exhaust gas routing is most clearly shown in FIG. 3 in connection with F i g. 2 to recognize. In Fig. 3 take the heating flaps, here representative of the heating flap i4, their one end position in which the Heating chambers, here the heating chamber 17 as a representative, can be charged with the maximum amount of exhaust gas. The exhaust gas passes through the manifold 31 to the connection point 33 between the manifold 31 and the housing 28. The heating flap 14 directs the exhaust gas flow into the heating chamber 17, specifically into the guide channel 22. From from here, the exhaust gas arrives in the guide channel 23 and occurs at the connection point 33 between the housing 28 and elbow 31, now behind the heating flap, re-enters elbow 31 and from here becomes the

directed into exhaust pipes. On his way through the two guide channels 22 and 23, the exhaust gas heats the heat-conducting partition 15 between the heating chamber 17 and the suction pipe 10 very intensively, especially the area of the smallest carburettors level 27. The same process takes place in the other Hit chamber 16 from. Since the two heating flaps 13 and 14 are moved synchronously with one another, the has Heating chamber 16 upstream heating flap 13 has the same position as the heating flap just described

with .

When the engine is started, the vacuum in the suction line is quite high and the vacuum unit 54 has their max. This maximum adjustment stroke corresponds to the position of the flaps 13 and 14 in

2i F i g. 1 and 3. The suction tube 15 is fully heated and the The temperature in the intake manifold increases very quickly, which is beneficial for mixture preparation during a cold start

In addition, a heat sensor, not shown, is also arranged in the suction pipe, which is also connected to the

jo vacuum unit 54 an adjustment of the heating flaps 13 and 14 causes. If the temperature in the intake manifold now rises above the desired intake manifold temperature or is the engine now operated in the partial load range, so that the negative pressure in the intake manifold decreases, the vacuum unit 54 thus effects an adjustment of the flaps 13 and 14 in one of the heating chambers 16 and 17 more covering way. In Figure 3, the heating flap 14 would be adjusted clockwise. Through this Part of the exhaust gas flows directly through the Exhaust manifold 31 (in the same way the exhaust manifold 30) without entering the heating chamber 17 (or into the Heating chamber 16). The heating chambers 16 and 17 are acted upon by a much smaller amount of exhaust gas, as a result of which the heat supply decreases the heating chambers 16 and 17 via the partition 15 to the suction pipe 10.

The arrangement of the heating chambers 16 and 17 under the suction pipe 10 and the geometric The design of these heating chambers changes

so intake manifold temperature very quickly with the changed heat supply. The control of the intake manifold temperature is therefore very sensitive and adapts quickly Changes in the operating condition of the engine. This means that even if the Operating condition of the engine, for example between full and partial load output, always the one for optimal Mixture preparation in the intake manifold required temperature can be set or maintained very precisely. The benefits are improved cold start and When the engine runs, an improvement in the load assumption and an improvement in exhaust gas. The fuel consumption decreases

The suction tube heating device according to the invention is absolute despite its simple design gas-tight, so that no exhaust gases can escape, for example at the bearings 39-42. This gas tightness is achieved by the design of the bearing parts 39-42 and the sealing elements 43-46 arranged there

guaranteed. The inventive design of the adjusting segment 55 ensures that this gas tightness of the bends 30 and 31 in no phase of the adjustment of the heating flaps 13 and 14 in Question is asked.

For this purpose 2 sheets of drawings

Claims (9)

Claims; t. Intake pipe heating device for a carburetor engine with one arranged at the bottom of the intake pipe, from this separated by a thermally conductive partition, acted upon by exhaust gases Boiler room and with two servomotor operated heating flaps upstream of the boiler room Control of the amount of exhaust gas flowing through the boiler room, characterized in that that the boiler room has two extensive, flat heating chambers (16, 17) which are separated from each other are separated and along the suction pipe (10), below the intended carburetor stage or Carburetor stages, extend side by side so that each heating chamber (16 or 17) through a transverse wall (18 or 19) is divided into two adjacent guide channels (20, 21 and 22, 23) arranged one behind the other in the longitudinal direction of the suction pipe (10), whose exhaust gas flow direction is successively opposite Uiid that each heating chamber (16 or 17) is connected to a separate exhaust gas line (11 or 12) and each heating chamber (16 or 17) one of the heating flaps (13 or 14) is assigned and that between the two Heating flaps (13, 14) a coupling for synchronous adjustment is provided 2. Device according to claim 1, characterized in that the suction pipe (10) and the heating chambers (16, 17) of a common housing (28) are surrounded, to which the two exhaust manifolds (30,31) are connected, and that the heating flaps (13,14) in the exhaust manifolds (30,31) near their connection points (32, 33) with the housing (28) are arranged 3. Apparatus according to claim 1 or 2, characterized in that the coupling between two rotatably mounted actuating shafts (36, 37) each rigidly connected to one of the heating flaps (13, 14) is arranged, and is formed by a non-rotatable corrugated tube (38). 4. Apparatus according to claim 3, characterized in that the adjusting shafts (36, 37) each in the Walls of the two exhaust manifolds (30, 31) are stored and in the bearing points (39,40,41,42) pass through the walls and that on one of the adjusting shafts (37) outside the exhaust manifold (30,31) engages a servomotor (53). 5. Apparatus according to claim 4, characterized in that the bearing points (39,40,41,42) in the Walls of the exhaust manifold (30, 31) flared to the outside and from the outside by means of the Adjusting shafts (36,37) arranged to be axially displaceable, spring-loaded, dome-shaped, temperature-resistant sealing elements (43,44,45,46) are sealed. 6. Apparatus according to claim 4 or 5, characterized in that on one of the adjusting shafts (37) arranged outside the exhaust manifold (30, 31) is an actuating segment (55) which is rigidly connected to it and on which one actuated by the servomotor (53) The control rod (56) is articulated in such a way that the two end points of the movement path resulting from the adjustment of the heating flaps (13, 14) Articulation point (57) lie on a straight line (58) aligned with the control rod axis. 7. Apparatus according to claim 6, characterized in that the adjusting segment (55) has a bore (59), in which one of the control rod (56) essentially right-angled pin (60) engages rotatably 8, device according to claim 6 or 7, characterized in that the adjusting segment (55) has two in Distance from each other arranged stop tabs (61, 62) carries, which one in the wall of the adjacent exhaust manifold (31) held stationary stop pin (63) is assigned 9. Device according to one of claims 1-8, characterized in that the servomotor (53) is designed as a vacuum unit (54)