JPS628629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a tube wall surrounding a mixing chamber with a series of main flow passages, the tube wall having a fuel distribution device in the upstream portion of the mixing chamber. It is provided in the form of an annular conduit opening into and configured as a heating wall downstream of the mixing chamber up to a throttle which can be actuated at will approximately from the area of the fuel distribution device, onto which the fuel distribution device directs the fuel. This invention relates to a mixture generator for an internal combustion engine, which comprises introducing the following.

Mixture generators of this type consist of a combination of the preparation of a sufficiently vaporizable mixture in the suction pipe in the mixing chamber and good conveying and distribution capabilities of the mixture.
When the mixture enters the suction pipe, almost no liquid fuel components are present anymore, and wetting of the walls in the mixing chamber is suppressed. The heat supplied via the heating wall causes direct heating and vaporization of the wall film of fuel over a short distance, thus avoiding excessive temperature rise of the suction mixture. Due to the rapid and short-distance evaporation of the wall film of fuel, no significant compositional errors of the suction mixture occur even in unsteady operation.

The object of the invention is to obtain improved mixture transport and pressure-dependent vaporization conditions in the mixing chamber within various engine operating ranges in the case of approximately constant underpressure conditions, i.e. The aim is to configure a mixture generator of the type mentioned at the outset in such a way that flow conditions are set without swirls or backflows.

To achieve this objective, a mixture generator of the type mentioned at the outset has the following features according to the invention. i.e. between a rotationally symmetrical air throttle which can be moved linearly in its longitudinal direction upstream of the mixing chamber and an inlet region of the tube wall which widens in the direction opposite to the flow direction. an annular air inlet that can be controlled by the constriction in a cross-section of a passage, and the air constriction being moved in the opening direction against the bias of the opening/closing spring until the forces are balanced by the negative pressure in the mixing chamber; a regulating unit connected to the air throttle which controls the air flow, and a control unit flow-connected to the annular line of the fuel distribution device which controls the position of the air throttle depending on the respective air charge; and one fuel metering device.
With such a mixture generator, the advantageous and uniform flow and mixture preparation conditions mentioned above result.
In the isobaric section of the mixing chamber, the suction air flows in an annular manner over the tube wall within the area of the fuel distribution device, so that the fuel is uniformly sucked into the mixing chamber from the annular channel in the tube wall, with No significant swirl or backflow occurs. The fuel already present in the wall area is vaporized indirectly in the area of the heated wall, unless it is entrained into the suction stream in minimal drops. The position of the air throttle corresponding to the respective air charge is used to introduce a fuel quantity into the isobaric zone that is suitable for the particular operating state. The special arrangement, configuration and direction of movement of the air throttle are such that the mixture generator according to patent application No. 55-160091 can be effectively established in connection with the isobaric principle stated for mixture preparation and mixture transport. It is possible to do so.

One particularly simple, expedient and advantageous embodiment with respect to the flow conditions is a conical widening of the tube wall facing away from the flow direction in the area of the air inlet and for said widening. and one circular plate-shaped air constriction with a complementary conical peripheral slope. This results in an annular conical air inlet, variable with respect to its thickness, which allows the uniform annular introduction of the sucked air flow into the isobaric section and the advantageous circumferential overflow into the annular fuel inlet. Make it possible to introduce it within the range. In addition, the contours corresponding to the air intakes associated with the adjusting unit allow for perfect air volume measurement.
The air charge is then proportional to the stroke of the air throttle.

The diaphragm box, which serves in particular as a regulating unit for the air throttle, is provided with a tube which mechanically connects the actuating diaphragm of the diaphragm box to the air throttle and flows through the working chamber of the diaphragm box to the mixing chamber. Link.
The connecting tube thereby retains a dual function, which simplifies the construction of the overall arrangement. The configuration is particularly suitable in combination with one diaphragm box connected in series to the mixing chamber at intervals on its longitudinal axis and an air inlet on the side between the diaphragm box and the annular air inlet. It is a purpose. Such an arrangement saves space on the one hand and favors flow on the other hand. This is because the air to be sucked in flows from all directions into the area between the diaphragm box and the annular air inlet and can be sucked in in a targeted manner through this. The connecting tube extends along the longitudinal axis of the mixing chamber and thus does not pose any hindrance to the air that surrounds this tube and is to be drawn in.

In yet another configuration, one compression spring with adjustable bias as one opening/closing spring on the diaphragm side in the working chamber and an air inlet on the side of one chamber on the other diaphragm side. There is one flow connection venting between. In particular, the venting flow connection of the chamber, which serves as a damper, is designed as a constriction. The suction air supplied to the air inlet, for example via an air filter, can therefore be used at the same time to vent the chamber of the diaphragm box. In addition, a more or less restricted flow connection achieves a greater or lesser damping process, so that the actuating diaphragm and thus the air throttle adapts its position in a correspondingly delayed manner to the respective operating situation. This will dampen transient driving shifts.

Instead of a ventilation flow connection or an associated part designed as a constriction of the diaphragm box, it is advantageous to provide a constriction in the working chamber of the diaphragm box, which has a pipe connected to the mixing chamber. Regardless of the presence and type of the throttle mentioned at the outset, this makes it possible, in particular, to brake the opening movement of the throttle without delay and thus to better adapt it to the respective operating situation. It is something.

The position of the air throttle, and thus also of the tube connecting it to the diaphragm box, corresponds to the respective air charge, so that in one simple embodiment the tube of the diaphragm box and the fuel metering can be A mechanical connection can be provided between the container and the container, for example in the form of a rigid rod. A change in the basic adjustment of the fuel metering device is possible by correspondingly changing the bias of the opening/closing spring in the working chamber of the diaphragm box.

One very advantageous alternative embodiment is an inductive displacement pick-up for producing an electrical measurement signal corresponding to an air throttle position and thus an air charge and an electrical measurement signal dependent on the air intake. It has a control device for regulating the fuel charge using a fuel metering device connected to an electro-magnetic valve. It is advantageous in this case to use a control device which has at least one correction variable input for varying the fuel/air ratio as a function of the measured operating parameter. Mixture generators of this type are significantly more variable and better adapted to the particular operating situation than those with one mechanical connection between the tube of the diaphragm box and the fuel metering device. It is something to do. Moreover, in this case there is no dependence on the local installation of the tube of the diaphragm box on the one hand, and of the fuel metering device on the other hand, which gives rise to further versatility. In addition, the basic adjustment of the fuel metering device can be carried out on the control device itself, so that no modification of the diaphragm box opening/closing spring is necessary for this purpose.

In order to distribute as uniformly as possible the fuel to be sucked in from one float chamber via the fuel metering device into the annular channel of the tube wall using equal pressure in the mixing chamber, at least one approximately radially joined It is expedient to provide two fuel lines and at least one auxiliary air line which join approximately tangentially. This results in a well-distributed premixture in the annular line to be drawn into the mixing chamber. It is particularly expedient in this case to provide two auxiliary air lines which are tangentially joined to the annular lines of the same direction, facing each other almost diametrically, and which are flow-wise connected to the air inlet on the side. One of them is connected approximately to the joining position of the fuel pipe line. This leads to a homogeneous premixture with good circumferential distribution in the annular conduit, so that this premixture can be introduced from the annular conduit into the mixing chamber uniformly over the entire circumference. .

In a further embodiment, the annular conduit is joined with a wide uniform circumferential distribution into the mixing chamber obliquely in the flow direction via the air intake conduit. In contrast to purely radial joints, diagonal joints have the advantage that strong flow diversions and thus swirls or backflows of the fuel are avoided. In addition, the distance of the junction point of the annular line from the air inlet is controlled depending on the presence of approximately the same negative pressure within this range and, therefore, the position of the air restriction with the fuel metering. It has the advantage that it can be done via a fuel metering device.

In particular, a thermal insulation is present between the heating wall and the annular conduit on the one hand and the float chamber connected thereto on the other hand. This avoids heating up the area of the float chamber and the fuel present therein.

In one particularly simple embodiment, the heating wall is configured as a heat exchange double wall through which engine cooling water flows. However, in principle other types of heating can also be used, such as electrical resistance heating as well as heating with hot engine gases.

The invention will be described in detail below with reference to illustrated embodiments.

The following description relates to the two embodiments of FIGS. 1 and 2 on the one hand and of FIG. 3 on the other hand, unless differences in this regard are indicated otherwise.

The mixture generator has a tube wall 1 surrounding a cylindrical mixing chamber 2 . The mixing chamber 2 is delimited downstream by a throttle 3 which can be actuated optionally in the form of a pivotable governor valve. In the area disposed toward the upstream side of the mixing chamber 2, there is a pipe wall 1.
a fuel distribution device 4 annularly connected from the chamber into the chamber;
is present together with one annular channel 5 in the tube wall 1. This annular conduit 5 joins into the mixing chamber 2 via a number of suction conduits 6 which are uniformly distributed along the circumference. These lines 6 are oblique to the longitudinal axis or main flow direction (arrow A) of the mixing chamber 2, and the fuel or premixture is already moving in the direction of arrow A in the suction line 6. It is becoming powerful.

As can be seen in FIG. 2, one fuel line 7 is joined radially to the annular line 5, and auxiliary air lines 8, 9, which lie diametrically opposite to each other, are connected tangentially in the same direction. are doing. The junction of the auxiliary air line 8 lies approximately close to the junction of the fuel line 7.
As a result, the fuel entering the annular line 5 is also given an evenly distributed annular flow by the sucked-in auxiliary air, so that the fuel entering the annular line 5 is given a homogeneous flow over its entire circumference. An air-fuel mixture is formed and this pre-air mixture is uniformly sucked into the mixing chamber 2 via the suction pipe 6.

The mixing chamber 2 is delimited at a distance upstream of the junction point of the suction pipe 6 by one air constriction 10 movable in the longitudinal direction of the mixing chamber 2, which constriction in this case It is constructed in the form of a plate with edge slopes not shown. Opposite this, the tube wall 1 of the mixture generator is widened in the direction opposite to the arrow A, so that the complementary slope of the air throttle 10 and the tube wall 1 lie opposite each other. Between these slopes there is an annular air inlet 11, the thickness or passage cross section of which depends on the position of the air throttle 10.

Downstream of the junction of the suction line 6 in the mixing chamber 2, the tube wall 1 is designed as a heating wall 12 approximately up to the throttle 3, and in this case one inlet 1
3 and one outlet 14 as a heat exchange double wall. The heated engine cooling water flows in the directions of arrows B and C, and heats the heating wall 12. Alternatively, heating walls heated electrically or by hot gas can also be used. Furthermore, combinations of these heating types are also possible.

The air restrictor 10 has a 15 in FIG. 1 or 40 in FIG. 3 disposed on the vertical axis of the mixing chamber 2.
Two regulating units are connected in series at intervals. The regulating unit 15 or 40 is mechanically connected to the air throttle 10 via a tube 16 extending along the longitudinal axis of the mixing chamber 2;
On the one hand, one actuating diaphragm 17 of the regulating unit 15 or 40 is mechanically rigidly connected to the air throttle 10, and on the other hand it is possible to control the flow between one working chamber 18 of the regulating unit 15 or 40 and the mixing chamber 2. We are starting to communicate with each other. As a result, a communication channel of a tube 16 (not shown in detail) passes through the actuating diaphragm 17 on the one hand and through the plate-shaped air throttle 10 on the other hand.

In the working chamber 18 there is a biased opening/closing spring 19 which is designed as a compression spring and which means that the air throttle 10 is connected to the air inlet 1.
1 to close the actuating diaphragm 17. The opening/closing spring 19 is supported on one side by the actuating diaphragm 17 and, according to FIG. Adjustment can be made using one screw 21.

On the side of the working diaphragm 17 facing away from the working chamber 18 there is one flow connection 23 leading outwards. This can be throttled more or less strongly in order to provide a certain damping action of the chamber 22 during transient operating transitions. A more advantageous damping is obtained in particular in the opening movement of the air throttle by means of one throttle 48 in the tube 16, which is connected to the flow connection 2.
It exists in place of or as an auxiliary to the constriction section No. 3.

In the circumferential area of the tube 16, the tube wall 1 has several air inlets 24, so that air flowing in the direction of the arrow D, for example from one air filter, can reach the annular air inlet 11. In this case, the auxiliary air lines 8, 9 are likewise connected in this area surrounding the pipe 16, so that the annular line 5 is also supplied with prepurified air.

A fuel metering device 2 in the form of a needle valve, the control of which must be elaborated further.
6 movably belongs to one nozzle 27 of one float chamber, which chamber has one ventilation section 2
9 and one nozzle 27 and has one dip tube 30 immersed in the fuel. The underpressure present in the isobaric section or mixing chamber 2 is transmitted via the suction line 6, the annular line 5 and the fuel line 7 to the fuel metering device 26, so that the fuel flows to the opening position of the fuel metering device 26. It can be inhaled accordingly. The float chamber 28 is directly connected to the region of the tube wall 1 which receives the annular channel 5 and is thermally insulated from the heating wall 12 via an intermediate chamber 31 . In addition, a heat blocking layer 32 is present in the tube wall 1 between the area receiving the annular ring 5 and the area of the heating wall. Heating of the float chamber 28 and the fuel therein can thereby be avoided.

In the first embodiment according to FIG. 1, the fuel metering device 26 is connected via a mechanical connection 25 to the line 16 of the regulating unit 15 in the following manner. This means that the fuel metering device 26 has a direct cooperative movement with respect to the nozzle 27 in response to the movement of the air throttle 10 and thus to the air charge. This results in an automatic adaptation of the fuel charge to the respective air charge. The position of the air throttle 10 and thus the basic adjustment of the fuel metering device 26 can be adjusted by biasing the screw 21, ie the opening/closing spring 19. Another possibility is that the connection position of the fuel metering device 26 can be changed correspondingly to the mechanical connection 25.

The second embodiment according to FIG. 3 differs from the first embodiment only in the following points. That is, the first
Instead of the mechanical connection 25 shown in the figure, an electrical control device is provided for the fuel metering device 26, which operates as a function of the movement of the air throttle 10. For this purpose, the tube 16 of the regulating unit 40 is equipped with one plunger-type armature 41 on the end side.
, which in one stationary coil 42 can engage more or less widely into the cap-shaped extension of the diaphragm box. The elements 41, 42 constitute an inductive displacement pick-up, the electrical measurement signal of which is proportional to the air charge of the mixture generator according to the position of the air throttle 10. This measurement signal is sent via an electrical connection 43 to an electrical control device 44, which via an electrical connection 45 and a magnetic valve 46 also determines the amount of fuel sucked in. The fuel metering device 26 is controlled in a manner proportional to the position of the air throttle 10 and thus to the air charge. At the same time, suitable operating parameters can be provided to the control device 44 via further inputs, thereby making it possible to correct the fuel-air ratio. Such corrections can prove useful, for example, in the case of cold starts, in the case of warm operation and in the case of compensation of measuring altitudes. The basic adjustment of the fuel metering device 26 can be carried out with the aid of the control device 44 itself, so that the support is now on the one hand relative to the actuating diaphragm 17 and on the other hand relative to the diaphragm box casing. It is not absolutely necessary to be able to separately adjust the bias of the opening/closing spring that is connected. A tube passage opening 47 is present between the tube 16 and the plunger armature 41;
This ensures that, regardless of the depth of penetration of the armature 41 into the coil 42, the working chamber 18 can always maintain the negative pressure of the mixing chamber 2.

In both embodiments, when the opening of the restrictor 3 is adjusted, the underpressure in the isobaric section or in the mixing chamber 2 increases. This negative pressure is transmitted into the working chamber 18 of the regulating unit 15 or 40, so that the actuating diaphragm 17 is moved upwards in the diagram against the action of the opening/closing spring 19. This means that the isobaric section or mixing chamber 2 is ventilated and the air intake is increased. When an equilibrium is achieved between the spring force of the opening/closing spring 19 and the negative pressure in the working chamber 18, the actuating diaphragm 17 and thus also the air throttle 10 remain stationary. This adaptation phenomenon of maintaining negative pressure only occurs under the assumption that the surface of the actuating diaphragm 17 is larger than the surface of the air restriction 10. There is a direct dependence between the negative pressure in the mixing chamber 2 and the spring force of the closing spring 19, as well as between the stroke of the air throttle 10 and the intake air charge. . In conjunction with the corresponding contours of the actuating diaphragm 17, the opening/closing spring 19, the working chamber 18 and the air intake 11, the air throttle 10 forms an air quantity meter, the air charge being determined by the air throttle 10. is proportional to the journey of The actuation of the fuel metering device 26 corresponds to the stroke of the air throttle 10, so that the fuel metering occurs in response to the air charge of the mixture generator. This mixture generator is most effective with respect to mixture conveyance and mixture preparation due to the special type of heating wall 12 and fuel supply and configuration, which is largely free from swirls or backflows and is quickly adapted to new operating conditions. It is suitable for Transient and other critical operating conditions are thereby also possible without any difficulty being considered. In addition, this mixture generator has the advantageous space-saving design mentioned above.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of a mixture generator in a schematic longitudinal section. Figure 2 is the first
A cross section along the - line in the figure is shown. FIG. 3 shows a second embodiment of a mixture generator in a schematic longitudinal section. 1... Pipe wall, 2... Mixing chamber, 3... Squeezer, 4
... Fuel distribution device, 5 ... Annular pipe, 6 ... Suction pipe, 7 ... Fuel pipe, 8, 9 ... Auxiliary air pipe, 10 ... Air throttle section, 11, 24 ... Air Suction port, 12... Heating wall, 15, 40... Adjustment unit, 16... Tube, 17... Operating diaphragm, 18... Working chamber, 19... Opening/closing spring, 22
... chamber, 23 ... flow connection, 25 ... mechanical connection, 26 ... fuel metering device, 28 ... float chamber, 31, 32 ... thermal insulation, 41, 42 ... inductive displacement Pickup, 44... Control device, 46
... Solenoid valve, 48 ... Throttle section.

Claims (1)

[Claims] 1 Consists of one tube wall that is connected to the main flow path and can be heated at a portion in the longitudinal direction, and one mixing chamber provided inside the tube wall, and the downstream side of the mixing chamber is It is limited to one restrictor that can be operated at will, and a fuel distribution device opens in the upstream portion of the restrictor, and the outer wall of the mixing chamber extends from the opening of the fuel distribution device approximately to the restrictor. is configured as a heating wall, the fuel distribution device guides the fuel to the heating wall, and the pipe wall is further provided with an annular pipe opening into the mixing chamber. One plate-shaped air constriction 10 located upstream of the chamber 2 and having a rotationally symmetrical conical peripheral slope movable linearly in its longitudinal direction, the conical peripheral slope of the air constriction 10 and the flow in this area. an annular air ring, which can be controlled by an air restriction 10 in the cross-section of the channel, between a conical widening complementary to the peripheral slope of the tube wall 1 widened in the opposite direction; The suction port 11 and the negative pressure in the mixing chamber 2 cause the air throttle part 10 to move in the opening direction against the spring force of the opening/closing spring 19 until the force reaches equilibrium with the opening/closing spring. Adjustment unit 15, 40 connected to the air throttle 10 for the air throttle 10 depending on the respective air charge
one fuel metering device 26 controlled according to the position of the fuel distribution device 4 and flow-wise connected to the annular conduit 5 of the fuel distribution device 4; A mixture generator characterized in that an annular pipe 5 is provided with openings opening into the mixing chamber obliquely in the direction in which air flows with respect to the vertical axis of the mixing chamber 2 with a peripheral distribution. 2 Adjustment unit 15 for air throttle section 10,
The diaphragm box serving as 40 is provided with a tube 16 which mechanically connects the actuating diaphragm 17 of the diaphragm box to the air constriction 10.
The mixture generator according to claim 1, characterized in that the working chamber 18 of the diaphragm box is connected to the mixing chamber 2 according to the flow. 3. characterized in that the mixing chamber 2 comprises one diaphragm box connected in series at intervals on its longitudinal axis and an air inlet 24 on the side between the diaphragm box and the annular air inlet 11; A mixture generator according to claim 2. 4 One compression spring with adjustable bias as one opening/closing spring 19 arranged on the diaphragm side in the working chamber 18 and one chamber 22 on the other diaphragm side and an air inlet 24 on the side. 4. Mixture generator according to claim 3, characterized in that it comprises one flow connection (23) for venting between. 5. Mixture generator according to claim 4, characterized in that the venting flow connection 23 of the chamber 22, which serves as a damper, is constructed as a throttle. 6 one constriction 4 in the working chamber 18 of the diaphragm box with the tube 16 connected to the mixing chamber 2;
8. The air-fuel mixture generator according to any one of claims 1 to 5, characterized by: 7. A mixture generator according to any one of claims 1 to 6, characterized by a mechanical connection 25 between the pipe 16 of the diaphragm box 15 and the fuel metering device 26. 8 an inductive displacement pick-up 41, 42 for producing an electrical measurement signal corresponding to the air throttle position and thus to the air charge;
One fuel metering device 26 connected to two solenoid valves 46
7. Mixture generator according to any one of claims 1 to 6, characterized in that it includes a control device (44) for adjusting the fuel charge using a fuel mixture generator. 9 at least one for varying the fuel-air ratio depending on the measured operating parameters S ₁ , S ₂ , S ₃
9. A mixture generator according to claim 8, characterized in that the control device 44 has two correction quantity inputs. 10. Claim 1 characterized by one annular line 5 with at least one fuel line 7 joining approximately radially and at least one auxiliary air line 8, 9 joining approximately tangentially The air-fuel mixture generator according to any one of items 9 to 9. 11 Two auxiliary air pipes 8 and 9 are provided, which are tangentially joined to the annular pipe 5 in the same direction, facing each other in exact opposite directions, and connected along the flow with the air suction port 24 on the side surface. 11. The air-fuel mixture generator according to claim 10, wherein one of the fuel pipes is joined at approximately the joining position of the fuel pipe line 7. 12 Float chamber 2 between the heating wall 12 and the annular pipe 5 on the one hand and connected thereto on the other hand
12. The air-fuel mixture generator according to any one of claims 1 to 11, characterized by thermal insulators 31 and 32 between the air and the air. 13. The air-fuel mixture generator according to any one of claims 1 to 12, wherein the heating wall 12 is configured as a heat exchange double wall through which engine cooling water flows.