US3613650A

US3613650A - Fuel injection system for internal combustion engines

Info

Publication number: US3613650A
Application number: US884206A
Authority: US
Inventors: Gerhard Stumpp; Klaus-Jurgen Peters
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1968-12-14
Filing date: 1969-12-11
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19
Also published as: AT313643B; FR2026172A1; GB1297974A; AT304171B; DE1814848B2; SE354097B; JPS5123649B1; DE1814848A1; DE1814848C3

Abstract

In the suction tube of an internal combustion engine there is disposed a regulator member which is displaceable by air pressure against the force of a return spring tensioned as a function of engine temperatures. Said regulator member is associated with a fuel metering device to vary the proportion of fuel in the fuelair mixture. The fuel quantities are also varied as a function of an arbitrarily set butterfly valve disposed in the suction tube.

Description

United States Patent [72] Inventors Gerhard Stumpp Stuttgart; Klaus-Jurgen Peters, Affalterbach, both of Germany [2 1 Appl. No. 884,206

[22] Filed Dec. 11, 1969 [45] Patented Oct. 19, 1971 [73] Assignee Robert Bosch GmbH Stuttgart, Germany [32] Priority Dec. 14, 1968 [33] Germany [54] FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES 6 Claims, 9 Drawing Figs.

[52] US. Cl 123/119, 123/139 AW, 123/139 80, 123/140 CC, 123/140 FG, 261/39 A, 261/50 A [51 Int. Cl ..F02n 69/00, F02d 3/02 [50] Field ofSearch 123/119, 139 AW, 139 B0, 140 CC, 140 PG; 261/50 A, 50

AA, 39 A, 39 B [56] References Cited UNITED STATES PATENTS 2,098,202 1 H1937 Weber 2,128,079 8/1938 Dawes 2,523,798 9/1950 Winkler 2,583,406 1/1952 Arnold 2,774,343 12/1956 Schafferetal .13.

Primary Examiner-Wendell E. Burns Attorney Edwin E. Greigg 261/50 AA 261/50 AA 261/50 AA 261/50 AA ABSTRACT: In the suction tube of an internal combustion engine there is disposed a regulator member which is displaceable by air pressure against the force of a return spring tensioned as a function of engine temperatures. Said regulator member is associated with a fuel metering device to vary the proportion of fuel in the fuel-air mixture. The fuel quantities are also varied as a function of an arbitrarily set butterfly valve disposed in the suction tube.

PATENTEDUCT 19 I971 SHEET 8 0F 7 5P 5 w w; W mama 4 w. 6 m

BACKGROUND OF THE INVENTION This invention relates to a fuel injection system for externally ignited internal combustion engines of automotive vehicles and is of the type wherein the supply of air is controlled by an arbitrarily operable butterfly valve disposed in the suction tube. The intake air flows past a regulator member which is responsive to the pressure (particularly the dynamic pressure) of the air in the suction tube, and which is disposed at least partially inside the suction tube and is displaceable against the force of a return spring. The position of the regulator member is a function of the flow rate of air determined by the setting of said butterfly valve. The regulator member, by virtue of its displacement, automatically determines a flow passage section in the suction tube and, according to said flow passage section, meters the fuel continuously by varying an adjustable throttle through which the fuel flows with a constant pressure drop.

The purpose of a fuel injection system of the aforenoted type is to automatically provide, in an Otto-engine, in all operational ranges a favorable ratio of fuel-air mixture in order to achieve a possibly complete combustion of the fuel and thereby ensure the highest possible efficiency of the engine, a lowest possible fuel consumption and further ensure that the generation-of poisonous exhaust gases is eliminated or at least very substantially reduced. For this purpose the fuel quantity has to be very accurately metered for each operational range of the engine. Conventionally, the butterfly valve is arbitrarily set dependent upon the required power, while the regulator assembly has the function to meter the fuel for obtaining the optimal ratio of fuel-air mixture.

In known fuel injection systems of the above-discussed type, as disclosed, for example, in British Pat. No. 1,066,721, the fuel is metered in the aforeoutlined manner as a function of the flow rate of air in the suction tube. Since it is insufficient to set a constant fuel-air ratio for each operational range of the engine, this ratio is adjusted to the operational conditions by means of additional devices, for example, by increasing the fuel proportion for large loads or as long as the engine operates below a desired temperature. In such known fuel injection systems, the ratio control of the fuel-air mixture is perfonned A. by a pressure-sensitive regulator member disposed upstream of the butterfly valve and displaceable against the force of a spring to control automatically the effective flow passage section of a variable channel in the suction tube and to simultaneously control the flow passage section of a fuel-metering nozzle, and

B. by pressure control means, which under constant rpm. and identical load conditions maintain a constant pressure drop at the metering nozzle, but which, however, alter such pressure drop for enriching the mixture, for example, when the engine runs cold.

A variation of the fuel proportion of the fuel-air mixture by changing the pressure drop at the metering nozzle by means of pressure control components is excessively complex and expensive.

The aforenoted known fuel injection system has further the disadvantage that the matching of the fuel-air ratio with the engine characteristics does not follow point by point, but, because of the use of the aforenoted pressure-responsive means, it is performed in such a manner that the metered fuel quantity has an optimal value for some operational conditions, whereas in wide operational ranges the fuel quantities do not correspond accurately to the requirements.

In another known fuel injection system of the type outlined hereinbefore and disclosed, for example, in German Pat. No. 1,191,177, there is provided a device wherein a second throttle member controls a pneumatic setting motor which is associated with a fuel metering valve which, in turn, detennines the fuel-air ratio as a function of the pressure prevailing in the suction tube between the butterfly valve and the aforenamed second throttle member. This second throttle member is disposed in the suction tube upstream'of' the first throttle member (i.e. the butterfly valve) and is operated'in its opening direction by the vacuum prevailing between the two throttle members and bythe pressure prevailing upstream of the second throttle member. For such a system, too, as far as the continuous fuel injection is concerned, the disadvantages mentioned hereinbefore apply.

OBJECT ANDSUMMARY OF THE INVENTION It is an object of the invention to provide an improved fuel injection system from which the above-noted disadvantages are eliminated and, particularly, as longas the engine runs hot, a near perfect combustion of the fuel is achieved with the simplest means.

Briefly stated, according to the invention, thebias or preload on the return force acting on the regulator member is changed as a function of a variable magnitude characterizing the engine operation, such as the engine temperature. The return force is supplied by a return spring, the bias or preload of which is variable by means of a temperature-dependent control element, such as an expansible regulator.

The aforenoted regulator member displaces-as afunction of the flow rate of air in the suction tube and as a function of the preload on said return spring-a three-dimensional cam which, in turn, adjusts a follower pin of a fuel quantity metering device. The three-dimensional cam is also displaceablein a direction normal to the movement caused by the regulator member as a function of the setting of the butterfly valve disposed in the suction tube.

The invention-will be better understood, as well as further objects and advantages will become more apparent, from the ensuing detailed specification of five exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWINGv FIG. I is an axial sectional view of a first embodiment of the invention;

FIG. 2 is a partial sectional view along line Il-II of FIG. 1;

FIG. 3 is a sectional view along line III-III of FIG. 2;

FIG. 4 is an axial sectional view of a second embodiment of the invention;

FIG. 5 is an axial sectional view of a third embodiment of the invention;

FIG. 6 is a partial sectional view along line VIVI of FIG.

FIG. 7 is a sectional view along line VII-VII of FIG. 6;

FIG. 8 is an axial sectional view of a fourth embodiment of the invention; and

FIG. 9 is an axial sectional view of a fifth embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS In the description which follows, the embodiments are discussed in a parallel manner. Reference numerals indicating components of identical structure and/or function are identical and are plain for the embodiments shown in FIGS. 1-4, but are provided with a prime sign for the embodiments depicted in FIGS. 5-9.

In all the embodiments, the intake air flow in the direction of the arrow in the suction tube 1, l and impinges against a baffle plate 2, 2' disposed normal to the direction of air flow and forming part of a pressure-responsive regulator member. The air also flows past an arbitrarily operable butterfly valve 3, 3' and proceeds to the cylinders of an internal combustion engine, not shown. In the embodiments shown in FIGS. 1-4, the baffle plate 2 is disposed upstream of the butterfly valve 3, whereas in the embodiments shown in FIGS. 5-9, the baffle plate 2 is disposed downstream of the butterfly valve 3'. In each figure the baffle plate shown in phantom lines represents a position thereof in which the flow passage section is at a maximum.

As shown in FIGS. 3 and 7, the fuel is drawn from a tank 4, 4' by means of a continuously operating pump 5, 5' and is delivered through a filter 6, 6' to a schematically shown fuelmetering device 7, 7. In order to maintain the pressure at a constant value, between the filter and fuel-metering device there is provided a pressure-limiting valve 8, 8' disposed in a return conduit. From the fuel-metering device 7, 7 there extend several fuel conduits 9, 9' to the fuel injection nozzles l0, 10' (only one shown).

The baffle plate 2, 2' is fixedly secured to one end of a guiding rod 11, 11' which is axially displaceably held in a sleeve 12, 12 mounted in the suction tube 1, 1' coaxially and stationarily with respect thereto. The guiding rod ll, 11 is provided, at its end distal from the baffle plate 2, 2', with an axial blind bore which threadedly holds a coupling part l3, 13'. The latter is provided with a deep annular groove 14, 14'.

Within the suction tube, perpendicularly to the longitudinal axis thereof, there is rotatably held a shaft 15, 15', the axis of which crosses at a distance that of the suction tube. With

shaft

15, 15 there is fixedly connected a lever 16, 16' which, by means of a lug 17, 17, projects into groove 14, 14"0f the coupling part l3, 13. To the lever l6, 16', between the shaft l5, l5 and the lug 17, 17, there is secured one end of a return spring l8, 18', which, with its other end, engages a setting lever 19, 19' pivotally supported by a stationarily held pin 20, 20'. The

setting lever

19, 19 is moved about the

pivot

20, 20 by means of a temperature-dependent control element 21, 21'. The force exerted by the latter is transmitted by means of a rod 22, 22' associated with a

force accumulator

23, 23.

That portion of the suction tube which lies between the baffle plate 2, 2 and the butterfly valve 3, 3' communicates, by means of a

bypass

24, 24, with another part of the suction tube on the opposite side of the

butterfly valve

3, 3. The lastnamed part of the suction tube is downstream of the butterfly valve 3 in the embodiments shown in FIGS. I4 and is upstream of the butterfly valve 3 in the embodiments illustrated in FIGS. 5-9, as it will be described in more detail as the specification progresses. The flow passage section of

bypass

24, 24 is controlled by a piston 25, 25' which is displaced together with the rod 22, 22' and the

force accumulator

23, 23.

In the embodiments according to FIGS. l-4, the butterfly valve 3 has a support shaft 26 rotatably disposed in the suction tube diametrically thereof and provided, at the end outside the suction tube, with a cam 27 (FIGS. 2 and 3). The cam 27 is in contact with one end of a follower lever 28 which, in turn, is swingable about a fixed pivot 29.

In the embodiments according to FIGS. 5-9, to the shaft 26 of the butterfly valve 3' there is fixedly attached a lever 27 (shown in plan view in FIG. 6) which, with a forked terminus, engages an annular groove of an axially displaceable actuating rod 30'. The other end of the latter has a second annular groove into which there extends a fork of one arm of a bellcrank lever 28' swingably secured about a fixed pivot pin 29'.

The bellcrank lever 28, 28 (FIGS. 2, 3 and 6, 7) engages, by means of a

roller

31, 31, a frontal face of a three-

dimensional cam

32, 32 which is axially displaceable on shaft 15, I5 against the force of a

return spring

33, 33 but which is prevented from rotating relative to said shaft. The threedimensional cam 32, 32' is in engagement with a

follower roller

35, 35 mounted on a

lever

34, 34 which is pivotally secured at one end and which, with its other end, actuates a pin 36, 36' of the fuel-metering device 7, 7.

In the embodiment according to FIG. 9, the pivotal point of lever 34' is stationary during normal engine operation, but is displaced by means of the temperature-dependent control element 21' through a bellcrank lever 38 and the extended rod 22' in order to deliver additional fuel quantities when the engine runs cold.

OPERATION OF THE EMBODIMENTS If the flow rate of intake air is increased in the suction tube due to a rotation of the butterfly valve 3, 3', the velocity of the air also increases in the flow passage section defined by the bafile plate 2, 2 and suction tube 1, 1. As a result, the pressure downstream of the baffle plate decreases and thus, the guiding

rod

11, 11 is displaced in the sleeve 12, 12' under the effect of the altered pressure difference upstream of and downstream of the baffle plate. The displacement of the baffle plate and the guiding rod is effected against the force of spring 18, 18' until, due to the increase in the flow passage section, the air velocity and thus the said pressure difference at least approximately reach their initial value. The

shaft

15, 15 and the three-

dimensional cam

32, 32 rotate during the displacement of the guide rod 11, ll

As the butterfly valve 3, 3' is turned, the three-dimensional cam is axially displaced on the shaft 15, 15' through shaft 26, 26', cam 27 (or lever 27' with the actuating rod 30'), bell crank

lever

28, 28 and roller 31, 31'. The fuel is metered dependent upon the flow rate of the air and upon the setting of the butterfly valve, through three-dimensional cam 32, 32', follower roller 35, 35', lever 34, 34', and follower pin 36, 36'.

Dependent upon the temperature of the engine, the preload on the spring l8, 18' is varied by means of the temperaturedependent control element 21, 21'. If the engine is cold, the said preload is small; on the other hand, if the engine has reached the desired operational temperature, the

return spring

18, 18 is tensioned (preloaded) to an increased extent resulting in a leaner fuel-air mixture. If the engine temperatures increase further, the

spring

18,18 is not tensioned to a greater extent since the lever l9, 19, when the desired temperatures are reached, engages an abutment 37, 37. Subsequent to such engagement it is solely the

force accumulator

23, 23 which takes up the expansion forces of

element

21, 21. As soon as the desired operating temperatures are reached, the bypass 24, 24', affecting the fuel-air mixture, is closed by the piston 25, 25'.

In the embodiments according to FIGS. 1, 5 and 9, the bypass 24, 24' is adapted to establish communication between those parts of the suction tube that are separated by the butterfly valve 3. As long as the bypass 24, 24' is maintained open by piston 25 (cold engine operation), the pressure-responsive regulator member is exposed to an air quantity which is larger than that set by the butterfly valve 3. As a result, an additional quantity of fuel-air mixture is delivered to the engine. This is particularly required because of the substantial frictional resistances prevailing in a cold engine. By an appropriate coordination of the temperature-dependent preload on the spring 18 and the traveled path of the piston 25, a desired ratio of fuel and air density may be obtained.

In the embodiments according to FIGS. 4 and 8, there is provided an additional possibility for affecting the aforenoted ratio. One part of the intake air, prior to its flowing past the butterfly valve or the regulator member, is directed through the bypass from the first section of the suction tube to the last section thereof as long as the engine is cold. The air channeled in this manner has thus no effect on the setting of the regulator member and therefore has no effect on the metered fuel.

The embodiments in which the regulator member is disposed downstream of the butterfly valve (FIGS. 5-9), have, with respect to the other embodiments, the disadvantage that the

shafts

15, 15 and 26, 26' are spaced relatively far from one another and require a linkage means 30'. The embodiments according to FIGS. 5-9 have, however, the advantage that the regulator member, due to the pulsating air flow through the engine cylinders, is in continuous oscillation so that the guide rod 11 is moved substantially without hysteresis losses in the sleeve 12'.

In the last embodiments (according to FIGS. 5-9), during idling, that is, when the butterfly valve 3 is almost closed, the density of the air flow effecting the motion of the regulator member changes downstream of the butterfly valve by virtue of the vacuum generated by the engine in the suction tube. Therefore, the three-dimensional cam 32' should be designed for this range in such a manner that small displacements of the regulator member from its position of rest cause no change in the fuel quantities. in order to obtain during cold engine operation an improvement of the fuel-air mixture, even in the aforenoted range, the pivotal point of the lever 34' is changed by means of the temperature-dependent control element through the bellcrank lever 38 and the rod 22.

The advantages of the fuel injection system according to the invention reside particularly in that by means of the combination of the pressure-responsive regulator member with the three-dimensional cam adapted to the engine characteristics, the fuel may be metered in a very accurate manner. MOre particularly, in the individual operation ranges (full load, partial load, idling) the desired mixture ratio (rich or lean) may be set by controlling the preload of the return spring of the regulator member and controlling a bypass of the suction tube with the aid of temperature-dependent means in such a manner that a desired rich mixture is obtained when the engine runs hot.

What is claimed is:

1. In a fuel injection system for internal combustion engines, said system being of the known type that includes (A) a suction tube for drawing intake air, (B) an arbitrarily operable throttle means disposed in said suction tube for controlling the supply of said air, (C) a regulator member at least partially disposed in said suction tube and displaceable therein the response to the pressure of air, said regulator member, dependent upon the flow rate of air determined by said throttle means, varies a flow passage section in said suction tube, said regulator member, dependent upon said flow passage section and by virtue of its displacement, continuously meters fuel by actuating a variable fuel throttle through which the fuel flows with a constant pressure drop and (D) means supplying a return force exerted on said regulator member and opposing the displacement thereof by said pressure, the improvement comprising A. a fuel-metering device having a following member, the displacement of which determines the fuel quantities delivered by said fuel-metering device,

B. a rotatably and axially displaceably held three-dimensional cam connected with said follower member, said cam is operatively connected with said regulator member and is rotatable thereby, said cam is operatively connected with said arbitrarily operable throttle means and is axially displaceable thereby and C. means for varying the preload on said return force as a function of a variable dependent upon the operation of said engine.

2. An improvement as defined in claim 1, wherein said means for varying the preload on said return force is a temperature-dependent control element, said improvement further includes A. a lever pivotable about an axis, said three-dimensional cam is connected with said follower member through said lever, said lever is operatively connected with said temperature-dependent control element and displaceable thereby to shift said last-named axis parallel to itself,

B. a bypass interconnecting portions of said suction tube and C. means connecting said temperature-dependent control element with said bypass to establish and break communication between said portions in response to the temperature of said engine.

3. An improvement as defined in claim 15, wherein said regulator member includes A. a baffle plate disposed in said suction tube normal to the flow of said air therein,

B. a guide rod fixedly attached to said baffle plate and extending parallel with the flow of said air and C. a guide sleeve fixedly held within said suction tube coaxially therewith, said guide sleeve slidably receives said guide rod.

4. An improvement as defined in claim 3, including A. a lever connected to said guide rod and turnab e thereby and B. a shaft affixed to said lever and rotatable thereby, said three-dimensioned cam is axially slidably mounted on said shaft and is constrained to rotate therewith as a unit.

5. An improvement as defined in claim 4, wherein said means supplying said return force is a spring, said means for varying the preload on said spring is a temperature-dependent control element; one end of said spring is attached to said lever, the other end of said spring is attached to an additional lever displaceable by said temperature-dependent control element for varying the preload on said spring.

6. An improvement as defined in claim 3, including A. a shaft rotatably held in said suction tube and carrying a throttle member fixedly attached thereto and forming part of said arbitrarily operable throttle means,

B. a cam affixed to said shaft and rotating therewith in unison,

C. a level pivotable about a stationary axis, one end of said lever carries a follower in engagement with said lastnamed cam, the other end of said lever is in engagement with said three-dimensional cam to displace the latter axially dependent upon the rotation of said shaft and D. a spring in engagement with said three-dimensional cam to oppose the axial displacement of the latter caused by said lever.

Claims

1. In a fuel injection system for internal combustion engines, said system being of the known type that includes (A) a suction tube for drawing intake air, (B) an arbitrarily operable throttle means disposed in said suction tube for controlling the supply of said air, (C) a regulator member at least partially disposed in said suction tube and displaceable therein the response to the pressure of air, said regulator member, dependent upon the flow rate of air determined by said throttle means, varies a flow passage section in said suction tube, said regulator member, dependent upon said flow passage section and by virtue of its displacement, continuously meters fuel by actuating a variable fuel throttle through which the fuel flows with a constant pressure drop and (D) means supplying a return force exerted on said regulator member and opposing the displacement thereof by said pressure, the improvement comprIsing A. a fuel-metering device having a following member, the displacement of which determines the fuel quantities delivered by said fuel-metering device, B. a rotatably and axially displaceably held three-dimensional cam connected with said follower member, said cam is operatively connected with said regulator member and is rotatable thereby, said cam is operatively connected with said arbitrarily operable throttle means and is axially displaceable thereby and C. means for varying the preload on said return force as a function of a variable dependent upon the operation of said engine.

2. An improvement as defined in claim 1, wherein said means for varying the preload on said return force is a temperature-dependent control element, said improvement further includes A. a lever pivotable about an axis, said three-dimensional cam is connected with said follower member through said lever, said lever is operatively connected with said temperature-dependent control element and displaceable thereby to shift said last-named axis parallel to itself, B. a bypass interconnecting portions of said suction tube and C. means connecting said temperature-dependent control element with said bypass to establish and break communication between said portions in response to the temperature of said engine.

3. An improvement as defined in claim 15, wherein said regulator member includes A. a baffle plate disposed in said suction tube normal to the flow of said air therein, B. a guide rod fixedly attached to said baffle plate and extending parallel with the flow of said air and C. a guide sleeve fixedly held within said suction tube coaxially therewith, said guide sleeve slidably receives said guide rod.

4. An improvement as defined in claim 3, including A. a lever connected to said guide rod and turnable thereby and B. a shaft affixed to said lever and rotatable thereby, said three-dimensioned cam is axially slidably mounted on said shaft and is constrained to rotate therewith as a unit.

6. An improvement as defined in claim 3, including A. a shaft rotatably held in said suction tube and carrying a throttle member fixedly attached thereto and forming part of said arbitrarily operable throttle means, B. a cam affixed to said shaft and rotating therewith in unison, C. a level pivotable about a stationary axis, one end of said lever carries a follower in engagement with said last-named cam, the other end of said lever is in engagement with said three-dimensional cam to displace the latter axially dependent upon the rotation of said shaft and D. a spring in engagement with said three-dimensional cam to oppose the axial displacement of the latter caused by said lever.