Combustion Motor

Abstract

A combustion motor in combination with a device for the automatic quantitative controlling of the air intake through a suction canal including a throttle valve, an apparatus for measuring the number of revolutions of the motor and deriving an actual value signal therefrom, a desired value source for providing an electrical magnitude corresponding to the desired value of the number of revolutions of the motor, a device for deriving the difference between the actual value and desired value magnitudes, and a switching logic for determining the control relationship affecting the positioning means of the throttle valve.

Parent Case Text

This is a continuation, of application Ser. No. 90,606, filed Nov. 18, 1970 now abandoned.

Description

FIELD OF THE INVENTION

The present invention relates generally to a combustion motor, and more particularly, it relates to a combustion motor having a device for the automatic quantitative controlling of the air intake.

BACKGROUND OF THE INVENTION

According to past experience it has been desirable for various reasons to provide a combustion motor with a device for the automatic and quantitative regulation or control of the air intake through a suction canal having a choke or throttle therein. For example, it has been attempted to obtain a possibly stable and low idle which would substantially depend only from the air intake. The solution of this attempt has been made difficult by the fact that the air requirement for a constant idle of the motor is different for each temperature in which the motor is operating. For example, at cold start a relatively large amount of air is necessary, while the quantity of the air has to be reduced in the next warm running phase. It became known to handle this situation by the provision of an additional air valve operable with a heated bimetal control member. The control characteristics of this control process cannot be, however, selected exclusively with the consideration of the constant number of revolutions, since there are also other factors which should be drawn into consideration so that a compromise could be reached.

In addition to the constant aspect of the motor revolutions during the stationary idle run, in connection with motors which operate with a reduced fuel feed above a predetermined number of revolutions or rotational speed of the motor, one may find it of interest to retain a constant number of revolutions per minute or speed also during the motor braking or decelerating operation after the number of revolutions per minute or speed of the motor falls below the predetermined number of revolutions.

Furthermore, there might be cases of interest in which instead of a constant number of revolutions rather a predetermined relationshihp between the air intake and the number of revolution of the motor is required. This problem can, for example, arise in connection with attempts to purify the exhaust gas.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a combustion motor having an automatic quantitative control of the rate of air intake at certain instances of the operation. It is a more specific object of the present invention to provide a control arrangement in a combustion motor for the automatic quantitative control of the air intake during a stationary idle run or during deceleration.

The combustion motor according to the present invention is provided with a device for the automatic quantitative control of the rate of air flow through a suction canal having a throttle valve therein and wherein the control arrangement includes the throttle valve itself as an adjustable member and a position drive therefore, a device for the measuring of the actual number of revolutions per minute or speed of the motor and providing an actual value reading thereof, a device for supplying a magnitude corresponding to the desired value of the motor revolutions, a member forming the difference between the actual and desired values of the motor revolutions per minute or speed, a switching or logic member connected between the positioning drive and the difference forming member and operable for determing the control relations in response to the difference magnitude and operating positioning drive of the throttle valve. According to the invention preferably an electronic tachometer is used for the measuring of the revolutions of the motor.

The throttle valve may be in the form of a control element having a straight line control movement, that is, a slide valve. In the preferred embodiment of the present invention, however, the throttle valve together with a positioning drive are formed as an electro-mechanical angular adjustable member. The invention also provides that the adjustable member is either null-symetrically or not null-symetrically formed. In the first mentioned case, the adjustable member as soon as the revolutions of the motor reach a desired value, becomes current-free or deenergized for the warm motor, and the throttle valve takes up a median position. In the case of a not-null-symetrical adjustable member even after the desired value of the motor revolution per minute or motor speed has been reached, an excitation of the adjusting or positioning drive is still necessary. The rest position of the throttle valve here corresponds to its fully open or fully closed state.

As have been pointed out above the invention provides a member for the forming of the difference between the actual and desired values of the motor revolutions. This member is constructed in the form of a difference amplifier.

According to the invention it is preferred that between the switching or logic member and the throttle positioning drive, a difference-power amplifier is connected which then responds to the switching or logic member. The function of the switching or logic member is described in more detail hereinafter and it can be said in general that its function is to determine the regulating characteristics and, as the case might be, to impose certain control magnitudes on the regulating magnitudes. A preferred form for the construction of the difference-power amplifier is characterized by the presence of a pair of transistor devices which are controlled by signals derived from the actual and desired values and further controlled by the switching or logic member.

As has been mentioned above, the extent of the control of the air quantity as well as the behavior of the regulating characteristics depend from the objects which are to be attained by the control itself. Accordingly, the scope of the present invention includes a great variety of possibilities for the construction of the switching or logic member of which only a preferred embodiment is described and illustrated in the drawings. It might be of interest to note that sometimes it is not desired that the control circuit should respond when the motor revolutions deviate somewhat only during a short period of time from the desired value of the revolutions. In order that a certain amount of delay affect could be introduced in this case, it is proposed that a control arrangement according to the present invention should include integrating units for the setting of a time constant associated with the control process.

It is understood that one has to provide for a certain amount of damping in the control circuit in order that the control circuit remain stable and to prevent it from becoming susceptible to oscillations. This can be done by appropriate dimensioning of the resistors, such as in the circuits associated with the control electrodes of the transistors in the circuit.

The structural features associated with the constructing of the suction canal are also within the scope of the present invention. In the preferred embodiment, the suction canal contains a main throttle valve bypassed with a control bypass canal in which a control throttle valve forming the control member is placed. In this case, and in accordance with the invention, the control takes place independently and additionally to the air intake control performed by the accelerator and affecting the main throttle only.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more readily apparent from the following description of preferred embodiments thereof shown in the accompanying drawings, in which:

FIG. 1 is a block diagram of the control circuit according to the present invention;

FIG. 2 is a circuit diagram of a preferred embodiment of the present invention illustrating the essential electronic elements of the control circuit;

FIG. 3 is a circuit diagram illustrating a preferred embodiment of the switching or logic member;

FIG. 4 is a time diagram illustrating the effect of the control process according to the present invention at different stages of the operation of the motor; and

FIG. 5 illustrates an embodiment according to the present invention showing a possible disposition of the control throttle valve with respect to the main throttle valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1 it is seen that a motor 1 receives the air necessary for the burning of the fuel through a suction canal 2 in which as an essential element of the control circuit according to the present invention a positioning element 3 is placed which in the embodiment hereinafter described, is a throttle valve having a positioning drive associated therewith which together form an electro-mechanical angularly adjustable member.

In order to obtain the control signal 4 which is fed to the positioning member 3, a device 5 for the measuring of the number of revolutions, such as a tachometer or other electronic measuring device adapted for this purpose, is used and which is capable of deriving an electrical magnitude U1 corresponding to the instantaneous number of actual revolutions of the motor 1. Furthermore, a reference source of desired number of revolutions 6 in FIG. 1 or 20 in FIG. 2 is present which is so constructed that it develops a voltage U2 which is proportional to the desired number of revolutions of the motor at each instance of regulation. The actual value magnitude U1 and the desired value magnitude U2 are, in this embodiment of the invention, fed to a difference amplifier 7 at the output of which the regulating deviation signal, that is, the difference between the two voltages U1 and U2 appears in the form of a voltage magnitude 8 at points 30, 30a which is adapted to be simply processed further. This control signal 8 is fed to the input of a difference power amplifier 9 which in turn is influenced as described in more detail in connection with FIG. 3 by a switching or logic member 10. The switching or logic member 10 provides the necessary form of the regulating characteristic lines and can also superimpose control characteristic lines onto the regulating characteristic lines as hereinafter described in more detail in connection with FIG. 3.

FIG. 3 is a circuit diagram illustrating the structure of the difference amplifier 7 and of the difference power amplifier 9. FIG. 2 contains furthermore two important switching elements which are shown in a block form by dashed lines, namely, the desired value reference source or generator 20 which can be built in a known manner and an integrating unit 21 which serves for the setting of a predetermined regulating delay, such as explained in connection with short deviations between actual and desired values infra.

Considering first the difference amplifier 7, it comprises as essential elements two transistors 22 and 23 having emitter and collector resistors associated therewith which are dimensioned so that they are capable of preventing an oscillation of the amplifier 7. The base electrode of the transistor 22 is connected over a resistor 24 to a terminal 25 to which the voltage U1 is applied which, as mentioned above in connection with FIG. 1, represents the actual value of the number of revolutions of the motor 1. The base of the transistor 23 receives the voltage U2 corresponding to the desired value of the revolutions of the motors as developed by the desired value sensor or generator 20 at terminal 26. The desired value generator 20 contains as an essential element a Zener diode 27 and resistors 28 and 29 which in a given case are temperature sensitive resistors and form a variable voltage divider together with Zener diode 27 for the setting of the voltage magnitude U2 at point 26 corresponding to the desired value of the number of revolutions. Between points 30 and 30a, that is, between the collectors of the transistors 22, 23 lies the difference between the two voltages U1 and U2 which is also in the form of a voltage magnitude and which is fed over resistors 22a, 23a, 31a, 32a seen in FIG. 2 to the base electrode of transistor 31 and 32 constituting the elements of the difference power amplifier 9. The amplified output voltage of this power amplifier 9 appears as the control magnitude 4 and is fed to the positioning member 3 as mentioned already in connection with FIG. 1.

The base electrodes of the transistors 31 and 32 are further connected through terminals 34 and 35 with the switching or logic member 10 illustrated in more detail in FIG. 3 so that the operational behavior effect of the difference power amplifier 9 can be controlled in addition to the regulating deviation represented by the voltage difference magnitude between voltages U1 and U2, also by the "program" or operation of the switching or logic element 10 as described in connection with FIGS. 3 and 4.

Short deviations such as oscillations commonly known in the regulating arts in the actual value of the number of revolutions from the desired value are supressed by the integrating member 21. This integrating member 21 consists of a capacitor 36 which is connected in parallel to the input of the voltage magntiude U1, that is, across the terminal 25, whereas in the series branch a resistor 25 is placed which also forms part of the integrating circuit 21.

FIG. 3 is an embodiment illustrating the construction of the switching or logic member 10. An essential element of the circuit is a transistor 40 to which in the present embodiment diodes 41 through 44 are connected in such manner and poling that a NOR-gate is formed as a positive logic member. The switching or logic member 10 shown in FIG. 3, for its operation is connected as illustrated in FIG. 2 through terminals 37 and 38 with the terminal 25 and with the desired value generator 20.

The switching or logic member 10 can be constructed in a manner that under stationary idle conditions a regulation is affected which provides a defined number of revolutions of the motor which, in given cases, can be also made a function of the motor temperature, or constant. During downhill run of a motor vehicle, it is desirable that above a certain number of revolutions per minute of the engine the fuel supply to it be interrupted. This is the so-called "deceleration fuel shut-off operation," which can be performed by a number of well-known arrangements. Upon the deceleration only the fuel already supplied becomes burned up, and no fuel supply takes place. However, if during the deceleration the number of engine revolutions per minute or engine speed falls below a certain minimum number of revolutions, in order to avoid stalling the engine in a subsequent acceleration stage, fuel must be supplied again. In other words, at this minimum number of revolutions or engine speed a suppression of the "deceleration fuel shut-off" takes place. In the event therefore, if we have a combustion motor having a deceleration cut-off above a predetermined value of a number of revolutions of the motor, under this circumstance the switching or logic member 10 can be constructed so that after the suppression of the deceleration fuel shut-off a regulating affect takes place at a constant number of revolutions of the motor. The switching equipment for the above-described type of switching or logic member 10 is relatively small. A construction of the switching or logic member 10 which is equally adapted to regulate the number of revolutions of the motor at a constant value even at a stationary idle run as well as after the suppression of the deceleration fuel shut-off, is characterized by the presence of a transistor, such as transistor 40 mentioned above, through the control throttle valve switch DK as well as through the deceleration fuel shut terminal SA, each being described in more detail in connection with FIG. 4, in such a manner that in the stationary idle run and at the suppression of the deceleration fuel shut-off, to both transistors 31, 32 of the difference power amplifier 9 a signal is fed by it which turns on these transistors.

The switching or logic member 10 can also contain or associated therewith pulse producing means, which upon attainment of the thrust operation stage, provides pulses additionally over conductors 37 and 38 to the positioning drive of the control throttle valve which affect further opening of the throttle valve for a short period of time. Such further opening allows an air intake which serves to completely burn the fuel which is already there, and thereby to avoid releasing unburned gases into the exhaust. These pulses which have been additionally produced do not constitute part of the regulating deviation signal 8 since they appear in the regulating direction after the logic member 10. Such pulse producing means can be in the form of appropriate RC combinations the operational affect of which appears in the form of capacitor discharge at the instant of the attainment of the deceleration stage. By such coupling of control pulses onto the control member 3 one may reduce the undesired carbo-hydrates in the exhaust gas as a result of the increasing air intake for a short period of time. The same will hold also when the deceleration fuel shut-off takes place.

The transistors 31 and 32 of the power amplifier 9 are switched only when the throttle valve switch DK (see FIG. 3) is closed and the terminal SA lies at zero potential, otherwise the transistors 31 and 32 would be blocked by the zero potential through diodes 41 and 42 in the switching member 10.

These conditions for the terminal SA and for the throttle valve switch DK are provided by the electronic control device mentioned hereinbefore in connection with the features of fuel injection and of the deceleration fuel shut-off above a predetermined number of revolutions. Such conditions suggest or require that in order to have a regulating effect, in the deceleration stage the number of revolutions must fall below those number of revolutions at which the deceleration fuel shut-off is suppressed.

The null-symetrical angular control element 3 (see FIG. 1) is in a current-free or unenergized by power amplifier 9 mid-point position when the throttle switch DK opens up or when the deceleration fuel shut-off terminal SA is operative. In this case the transistor 40 becomes switched from the DK or SA terminals by the aforementioned electronic control device so that the transistors 31 and 32 are blocked through the diodes 41 and 42.

FIG. 4 illustrates the time duration of the control process as a function of the potential present on the terminal SA as well as on the throttle valve switch DK. As a criterion for the effectiveness and the suppression of the regulation, the potential on the terminal 45 in the switching logic 10 (see FIG. 3) is used. Under operating conditions where either the throttle valve switch DK is open or on the terminal SA there is a potential which is different from zero, the transistor 40 is switched on and as a result the potential on the terminal 45 is so low that transistors 31 and 32 in the difference power amplifier 9 become blocked (see FIG. 2).

This blocking of the transistors can be further enhanced by a diode 39 in the common emitter circuit of the transistors 31 and 32.

The associated operating ranges of the motor can be seen in FIG. 4 as follows: The ranges b and c are the so called load and thrust operating ranges. FIG. 4 shows the potentials on the terminals SA and 45 as well as the throttle valve switch DK as plotted against a time axis.

On the other hand, in the ranges a and d which respectively correspond to the stationary idle run and to the onset of the fuel feed after the motor fell below a certain number of revolutions, at which the thrust cut-off becomes inoperative, the transistor 40 is blocked, so that the potential on the terminal 45 and thereby the potential on the bases of transistors 31 and 32 in the difference power amplifier 9 lie at such level that the power amplifier 9 and thereby the regulating process is in effect. In addition to the above-described pure regulating process a control magnitude can be added to the regulating characteristics through the terminals 37 and 38 (see FIG. 2).

FIG. 5 illustrates the constructive arrangement of the positioning member 3, comprising the control throttle valve 50, with respect to the air intake canal 51. The air intake canal consists of a main branch 52 as well as of a by pass 53 which bridges the main throttle valve 54 placed in the main branch 52. The reference numeral 55 identifies the positioning arrangement for the control throttle valve 50 which is energizable by the signals of the power amplifier 9 controled by the regulating magnitude 4. In the arrangement shown the control throttle valve 50 and the positioning arrangement 55 form together the positioning member 3 of the regulating circuit. While the positioning of the throttle valve 50 depends from the instantaneous regulating deviation and, in certain cases mentioned above, in addition also from other control instructions, which might be given by the switching member 10, the position of the main throttle valve 54 remains controlled only by the accelerator.

From the above, it is apparent that although the invention has been described hereinbefore with respect to certain specific embodiments thereof, it is evident that many modifications and changes may be made without departing from the spirit of the invention. Accordingly, by the appended claims, we intend to cover all such modifications and changes as fall within the true spirit and scope of this invention.

Claims

We claim:

1. A combustion motor comprising an air intake canal, throttle valve means in said canal determining the rate of air flow through said canal, a throttle valve switch operatively connected to said throttle valve means, said switch being closed during deceleration operation of the motor and said throttle valve means being moved into its closed position during deceleration operation of the motor and idling, a device for automatically controlling the motor speed during operation modes of the motor different from load and deceleration fuel shut off, said device comprising by-pass canal means bypassing said throttle valve means, a control throttle disposed in said by-pass canal means and comprising an electrical positioning arrangement, first means for measuring the actual value of the motor speed and deriving an electrical actual value signal therefrom, second means for providing an electrical desired value signal corresponding to the desired value of the motor speed, difference deriving means having input and output means, said first and second means being operatively connected to said input means of said difference deriving means, said positioning arrangement of said control throttle being operatively connected to said output means, switching means operatively connected to said input means, said switching means comprising a semiconductor device having a control electrode connectable via said throttle valve switch to an electrical potential adapted to block said semiconductor device and further connected to an electrical circuit point having an electrical potential also adapted to block said semiconductor device only during deceleration fuel shut off, said input means being connectable via said semiconductor device to an electrical potential adapted to block said difference deriving means, whereby during load operation and deceleration fuel shut off no electrical signal representing the difference between actual value and desired value of the motor speed is fed to said positioning arrangement from said difference deriving means.

2. The combination as claimed in claim 1, wherein said difference deriving means comprises a difference power amplifier.

3. The combination as claimed in claim 1, said device further comprising an integrating means for the setting of a time constant for said regulating process.