US3616780A

US3616780A - Electrically controlled fuel injection arrangement for internal combustion engines

Info

Publication number: US3616780A
Application number: US861280A
Authority: US
Inventors: Hans Joachim Helle
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1968-09-28
Filing date: 1969-09-26
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02
Also published as: DE1776155A1; FR2019128A1; DE1776155B2; AT291681B; DE1776155C3; SE341889B; GB1290182A; CH495502A

Abstract

A FUEL INJECTION ARRANGEMENT IN WHICH A MONOSTABLE MULTIVIBRATOR APPLIES CONTROL PULSES TO ELECTROMAGNETICALLY ACTUATED FUEL INJECTION VALVES OF THE ENGINES. A SWITCHING CIRCUIT IS LINKED TO THE THROTTLE OF THE ENGINE FOR THE PURPOSE OF APPLYING AUXILIARY INJECTION BETWEEN EACH TWO SUCCESSIVELY OCCURRING PULSES FROM THE MULTIVIBRATOR WHICH IS ACTUATED SYNCHRONOUSLY WITH THE ROTATIONAL SPEED OF THE ENGINE. THE SWITCHING CIRCUIT INCLUDES A CAM MEMBER WHICH IS COUPLED TO THE THROTTLE THROUGH AN OVERRUNNING SLIP CLUTCH. THE CAM MEMBER IS ROTATED WITH THE THROTTLE ONLY DURING THE OPENING MOTIRON THEREOF, WHEREAS THE CLUTCH DISENGAGES THE CAM MEMBER FROM THE THROTTLE WHEN THE LATTER EXECUTES CLOSING MOTIONS.

Description

H. J. HELLE 3,616,780 ELECTRICALLY CONTROLLED FUEL INJECTION ARRANGEMENT Nov. 2, 1971 FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 1 Filed Sept. 26, 1969 Filed Sept. 26, 1969 Nov. 2,1971 H. J. HELLE I 3,616,780

ELECTRICALLY CONTROLLED FUEL INJECTION ARRANGEMENT.

FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 1 v V 4,. I jg 4,! l/ 9 W n/r04 Am Joac/r/m 14 511 F fl 6/5 Arrow [y United States Patent O" U.S. Cl. 123-32 EA Claims ABSTRACT OF THE DISCLOSURE A fuel injection arrangement in which a monostable multivibrator applies control pulses to electromagnetically actuated fuel injection valves of the engine. A switching circuit is linked to the throttle of the engine for the purpose of applying auxiliary injection between each two successively occurring pulses from the multivibrator which is actuated synchronously with the rotational speed of the engine. The switching circuit includes a cam member which is coupled to the throttle through an overrunning slip clutch. The cam member is rotated With the throttle only during the opening motion thereof, whereas the clutch disengages the cam member from the throttle when the latter executes closing motions.

BACKGROUND OF THE INVENTION The present invention resides in an electrically controlled fuel injection arrangement for internal combustion engines, in which at least one electromagnetically actuated injection valve is provided with a magnetization coil energized from a power transistor connected in series therewith. A control multivibrator, futhermore, is connected in series with the power transistor and becomes actuated or switched to its unstable state, through pulses emitted synchronously with the rotational speed of the engine. The pulses emitted by the control multivibrator provide for opening of the injection valves. After a variable opening duration of the valve determined by the time interval of the multivibrator, the latter returns to its stable state. The throttle flap of the engine is, moreover, operated in conjunction with a switching arrangement for providing additional or auxiliary injection processes during the opening motion of the throttle flap and between two pulses occurring synchronously with the rotational speed of the engine.

Arrangements with electrically controlled fuel injection into the intake manifold of an internal combustion engine are already known in the art. In such conventional arrangements, a throttle flap of the engine is coupled to a pulse generator which include an induction coil into which a permanent magnet dips or is insertable. When the gas pedal is stepped upon, the permanent magnet is inserted into the induction coil and induces, thereby, a voltage into the coil. The magnitude of this voltage increases with the opening speed or velocity of the throttle flap. In the conventional arrangement, this induced voltage is applied to a transistor amplifier through which the reference voltage of the control multivibrator determining the length of the output pulse or duration of this pulse and thereby its resetting instant, may be varied. With this arrangement, the control pulse is extended in duration, and the increased fuel quantity injected by the injection valves over this extended period of time, serve for accelerating purposes through accelerating enrichment.

In simple injection arrangements, this conventional method based upon inductive means for applying fuel enrichment as a function of the throttle flap opening,

3,616,780 Patented Nov. 2., 1971 ice operated satisfactorily. The arrangement requires, however, a relatively large amount of equipment, since the permanent magnetic pulse generator must be constructed with small air gaps, so that considerable manufacturing precision is involved. This situation applies even to small or slow opening motions of the throttle, whereby a sufficiently large inductive signal is realized. Pneumatic systems are known in the art, in which the pressure rise within the intake manifold of the internal combustion engine is differentiated during opening of the throttle flap. These pneumatic arrangements, however, have the disadvantage that the control signal is delayed by approximately 40 to 70 msec. with respect to the throttle flap opening.

Accordingly, it is an object of the present invention to provide fuel enrichment for accelerating purposes, through the use of circuitry which requires only a substantially small amount of components and complexity. The circuit arrangement of the present invention is to be connectable to the throttle .fiap shaft, so that no time delay is encountered with respect to the throttle motion. The fuel enrichment, furthermore, is to be made dependent upon the opening path or motion of the throttle, and the opening speed thereof. It is to be made certain, thereby, that the circuitry be made operable only during the Opening motion and not during the closing motion of the throttle.

The preceding objects can be achieved through an electrically controlled fuel injection arrangement, in which the circuitry includes a rotatable cam having a plurality of sprocket-shaped teeth used for switching purposes. A free-running coupling is provided between the cam and the shaft of the throttle flap. The free-running coupling is arranged so that it will provide coupling action in the opening direction of the throttle shaft.

The circuitry can be advantageously designed when the free-running coupling is concentrically arranged with the cam, and is situated within an interior space of the cam. The free-runing coupling, furthermore, has a hub member which may be slipped onto the throttle shaft and a clamping roller, furthermore, resides between the circumferential surface of the hub member and the interior wall of the cam. The clamping roller lies, preferably, within a pocket-shaped portion of the hub member.

A lever, furthermore, cooperates with the sprocketshaped teeth on the circumference of the cam, and actuates switching contacts which consist, preferably, of at least two switching contacts on leaf springs. It is particularly advantageous when the lever is subjected to forced motion in relation to the cam peripheral area. The lever can be designed, for this purpose, with two arms and having an end zone at each arm resting against the peripheral surface of the cam. In a preferred embodiment, the lever has side walls extending backwards along both of its longitudinal rims. These side walls have transverse slots for mounting the lever upon a pin serving as a bearing member. A leaf spring may be advantageously inserted between these side walls and bent in shape so that it lies in the proximity of both end zones upon which the back side of the lever is in contact with the cam surface. The spring supports itself with its mid dle zone against the bearing pin of the lever, and maintains, thereby, the lever in contact with the sprocket teeth of the cam surface, through its tension. In this manner, an elastic three-point support for the lever may be realized, and forced motion of the lever is obtained for assuring actuation of the switching contacts, as required.

SUMMARY OF THE INVENTION A controlled fuel injection arrangement in which fuel is injected into the engine through the use of electromagnetically actuated injection valves. The control pulses for opening the valves are derived from a monostable multivibrator having a variable time interval corresponding to the unstable state of the multivibrator. The multivibrator is actuated synchronously with the rotation of the engine, by being linked to the crank shaft thereof. The output pulses of the multivibrator are amplified through a power transistor, and then applied to the coils of the electromagnetically actuated injection valves. A switching arrangement is linked to the throttle of the engine and operated as a function of the position thereof, during the opening motion of the throttle, for applying auxiliary injection between each two successively occurring pulses from the multivibrator. The switching arrangement also includes a cam member having sprocketshaped teeth about its circumference and rotatable through the throttle. An overrunning slip clutch, or freewheeling clutch or coupling connects the cam member to the throttle so that the cam becomes rotated only during the opening motion of the throttle. During the closing motion of the throttle, the clutch slips and disengages the cam member from the throttle.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial sectional view of the intake manifold of the internal combustion engine and shows the mounting of the throttle flap upon a shaft projecting with its ends out of the intake manifold and having mounted thereon a throttle flap switch, in accordance with the present invention;

FIG. 2 is a plan view along the axial direction of the throttle flap switch in FIG. 1, with parts broken away;

FIG. 3 is a sectional view taken along line IIIIII in FIG. 1;

FIG. 4 is a sectional view taken along line IVIV in FIG. 2; and

FIG. 5 is an enlarged view of the portions in FIG. 2 within the area outlined by a dash-dot circle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, within the intake manifold 1 of an internal combustion engine, the remainder of which is not shown, is a throttle flap 2 mounted upon a rotatable shaft 3. The throttle shaft 3 projects, with its ends, through the intake manifold. One end of this shaft 3 projects through a bearing boss 4 out of the intake manifold 1, and carries a lever 6. Coupled to this lever 6, is linkage 7 connected to the gas pedal of the internal combustion engine. Through this gas pedal which is not shown, and the linkage 7, the throttle flap may be rotated to the position shown in the drawing, corresponding to the open position, against the action of a return spring. The other end of the shaft 3 is provided with a flattened portion 8 which serves to transmit the rotational motion of the throttle to a hub member 9 of a throttle flap switch.

In particular, the throttle flap switch is comprised of a housing 10 made of plastics, for example, and is provided with two radially projecting mounting portions 11 and 12 having slots 13 for admitting mounting screws, not shown. A ring cam 15 is mounted concentric with the hub 9 and rotatable relative thereto. This ring cam 15 is shaped to have 48 teeth 16 about its circumference, the shape of which is clearly apparent from FIG. 5. This ring cam 15 is made of hardened steel. A shifting lever 17 designated with two arms, operates in conjunction with these teeth 16. The number of teeth is determined by the required number of injection pulses. This number of teeth can, moreover, be enlarged or made smaller through corresponding variation or modification in the lever 17. Forced motion of the lever 17 is realized through the condition that the lever with its end zones 18 and 19 rests against the teeth 16 in a predetermined manner. Thus, with one end zone of its two arms, the lever 17 rests against the rising surface of one of the teeth 16, whereas the other end zone rests against the rising or inclined surface of the seventh tooth counted along the circumference in the forward direction. A leaf spring 20 serves to apply the pressure or force for maintaining the lever 17 against the respective teeth 16. The spring is inserted under severe tension between the ring cam 15 facing the backside of the lever 17, and a bearing pin 22 which forms the rotatable axis of the lever 17.

The bearing pin 22 is secured at the base of the housing 10, and reaches into a guide slot 24 in each one of two side walls 25 and 26'. These side Walls project from the ring cam 15 facing the backside of the lever 17. Two fingers 28 and 29 are connected to the lever 17, and the finger 28, as shown in FIG. 5, reaches between two switching contacts of two switching arrangements. Each of the switching arrangement consists of

springs

35, 36 and 37, 38. Secured to these springs are, respectively,

contact portions

31, 32, 33 and 34. Each of the contact springs is conducti vely or electrically connected with one of the tongues 39 of a pin connector integrally formed with the housing, and not further shown.

When the ring cam is rotated in the direction denoted by the arrow in FIGS. 2 and 5, corresponding to the counter-clockwise direction, the end zone 18 becomes easily raised through contact with the respective tooth 16. With such raising of the end zone 18, the lever 17 turns in the counter-clockwise direction and presses, thereby, with its finger 28 against the contact spring 37, so that the

contact portions

33 and 34 are made to bear against each other. As soon as the particular tooth 16 which has raised the end portion 18 passes from underneath thereof, the other end zone 19* becomes actuated and moves in radial direction through the next on-coming tooth beneath this end zone 19. As a result, the lever 17 is now turned in the clockwise direction and the finger 28, thereby, now actuates the spring 36 so that

contacts

31 and 32 are brought together.

The aforementioned fuel enrichment is required only during the accelerating process which is initiated through stepping upon the gas pedal and thereby increasing the opening angle of the throttle flap. For the purpose of preventing that the throttle flap also actuate the swinging contacts during its closing motion, a free-running coupling is provided between the hub member 9 and the ring cam 15. This free-running coupling consists essentially of a clamping roller 40. For the purpose of receiving this clamping roller, a pocket is provided in the rim zone of the hub member 9 facing the ring cam 15. This pocket is formed through a short and substantially radial wall portion 41, and a Wall 42 so as to form a tangential seating angle for the roller 40, with the wall 41.

When the hub member is rotated in the direction of the arrow during the opening motion of the throttle flap, the clamping roller 40 becomes held or clamped between the wall 42 and the inner circumferential surface 43 of the ring cam 15. As a result of this clamping action, the ring cam is carried along. In order to assure a secure clamping effect in this rotational direction, a bore 44 is provided through the shorter wall 41 of the pocket. This bore 44 contains a substantially low-tensioned spring 45. Through a guide member 46, this spring 44 presses against the clamping roll which is consequently pressed between the clamping surfaces, so that during the opening rotational motion of the throttle flap, the ring cam 15 is carried along without any noticable slip. Accordingly, the number of switching actuations carried out on the switching contacts or springs 35, 36 and 37, 38 are made to correspond to the magnitude of the open-motion of the throttle. When the throttle flap closes, however, the clamping roller releases immediately the ring cam so that the latter remains stationary and the lever 17 does not carry out any rotations or oscillations.

For the purpose of maintaining at a minimum the production costs of the throttle flap switch, and to simplify its construction, the position of the ring cam 15 in relation to the clamping roller 40 and the hub member 9, is fixed through two ring-shaped

discs

48 and 49 on both sides of the cam member. These ring discs are soldered to the hub member 9 with the aid of two pins 57 and the stem 50 of a switching pin 51. This switching pin 51 projects from below the ring disc 49, and closes, in the idling state of the throttle flap 2, the two idling contacts 52 and 53 shown in FIG. 3. A spring 55 is, furthermore, secured to the switching pin 51. This spring 55 presses against the flattened portion 8 through an elongated slot 56. With such pressure applied to the flattened portion 8, assurance is had that the hub member is positively carried along with the rotation of the throttle flap shaft.

The particular advantage of the embodiment of the present invention for the throttle flap switch resides in the feature that it may be produced economically and is simple in construction. At the same time, the operating life of this switching arrangement is extremely high. Furthermore, the throttle flap switch may be used for the other rotational direction by interchanging the idling contacts, the transfer contacts, and the reversing of the freerunning action of the clamping roll. Such reversal in rotation may be accomplished without any separate means. Since the rotational direction of the throttle flap opening depends upon the type of the internal combustion engine used, and is different for different engines, it is important to note whether right hand or left hand directions are under consideration.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in fuel injection arrangements for internal combustion engines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In an arrangement of the character described, a combination comprising an intake manifold of an internal combustion engine; a throttle in said manifold movable between open and closed positions; switching means fixed relative to said manifold and linked to said throttle to be operated by movement of the same in opening direction;

cam means in said switching means and rotatable by said throttle, said cam means having a plurality of tooth shaped portions for operating said switch means through the link; and coupling means between said cam means and said throttle for engaging said cam means with said throttle during opening movement of said throttle and disengaging said cam means from said throttle during closing motion of said throttle.

2. The combination as defined in claim '1 wherein said coupling means comprises a hub member linked to said throttle and movable therewith within an interior space of said cam means; and at least one clamping roller member between the circumferential surface of said hub member and the interior wall surface of said cam means.

3. The combination as defined in claim 2 wherein said hub member has a pocket-shaped portion for confining said clamping roller member.

4. The combination as defined in claim 1 including lever means in cooperative operating contact with said tooth-shaped portions of said cam means; and switching contact means actuated by said lever means.

5. The combination as defined in claim 4 including leaf spring means for supporting said switching contact means.

6. The combination as defined in claim 4 wherein said lever means comprises a two-arm lever bearing against the circumferential surface of said cam means with the end portions of the two arms of said lever means.

7. The combination as defined in claim 4 including side walls on said lever means and projecting backwards along both of the longitudinal edges of said lever means, said side walls having transverse slots; and bearing pin means passing through said transverse slots for supporting said lever means.

8. The combination as defined in claim 7 including spring means supported on said cam means and facing said lever means, said spring means extending along the longitudinal direction of said lever means and bearing against said bearing pin means, said spring means being tensioned between said bearing pin means and said lever means.

9. The combination as defined in claim 1 wherein said coupling means comprises an overrunning slip coupling.

10. The combination as defined in claim 8 wherein said spring means comprises a leaf spring lying with its middle portion against said bearing pin means.

References Cited UNITED STATES PATENTS 3,504,656 4/1970 Bastam et al. 123-1l9 X LAURENCE M. GOODRIDGE, Primary Examiner US. Cl. X.R. 123-119, 127