GB2135387A

GB2135387A - Gear-change indicating arrangements

Info

Publication number: GB2135387A
Application number: GB08318883A
Authority: GB
Inventors: Norbert Stelter; Friedrich-Wilhelm Kaiser; Johann-Georg Ulrich; Werner Grozinger
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 1982-07-17
Filing date: 1983-07-13
Publication date: 1984-08-30
Also published as: GB8318883D0; DE3226829A1; FR2530203A1; IT8321193A1; JPS5932523A; GB2135387B; DE3226829C2; IT8321193A0; IT1194248B

Abstract

An arrangement is provided for determining and indicating a warning signal 6 to a driver of a motor vehicle that he should change gear. The signal is in response to operating conditions, namely vehicle speed v, engine speed n, injection time ti, cooling water temperature ???, and the gear engaged. An operating range 21 unfavourable for fuel consumption is determined in an injection time-rotational speed diagram by a control apparatus 5 and if the operating point of the engine lies within this operating range, then a visual or audible warning signal is given to change up. The line 19 is so selected that after the change up sufficient acceleration capability is preserved. <IMAGE>

Description

SPECIFICATION Improvements in or relating to gear-change indicating arrangements The present invention relates to an arrangement for the determination and indication of a warning signal for the shifting of a motor vehicle change-speed transmission, informing the driver of the motor vehicle either optically or acoustically to drive the engine in a more economical range by shifting to a higher transmission ratio.

Such an arrangement for providing a gearchange indication, as described in the German Offenlegungsschrift 20 29 634, offers the advantage compared to fuel consumption indicating arrangements that the driver of the motor vehicle is given an indication of how he can economize on fuel. For that purpose, in the known arrangement, the engine rotational speed and the load are indicated by two pointers on two scales in an indicating apparatus of the motor vehicle.

The driver attempts to position the point of intersection of the two pointers by actuation of the accelerator pedal and/or engagement of a higher gear that he falls into a range of low fuel consumption on the curves of the specific fuel consumption visible on the indicating apparatus.

Since the driver of the motor vehicle must therefore constantly observe the load indicator and the rotational speed indicator and must adjust their mutual rotational positions to a favourable fuel consumption by changing his manner of driving, he acts like a part of a control circuit. Such activity can be carried out in stationary installations, but hardly in a motor vehicle which moves in road traffic. It would distract the driver far too much from the traffic.

According to one aspect of the invention, there is provided an arrangement for providing an optical or acoustic indication for notifying a driver of a motor vehicle optically or acoustically to drive an engine of the vehicle in a more economical range by changing to a higher transmission speed by providing a signal determined as a function of measure characteristic magnitudes comprising vehicle velocity, engine rotational speed, load or injection time, and cooling water temperature which are supplied to a control apparatus, in which a fuel-unfavorable operating range of the engine is determined as a function of the temperature and of the engaged speed, which is limited by an operating line injection time as a function of the engine rotational speed, and in which a changing-up signal is produced when the operating point of the engine lies within the operating range.

According to another aspect of the invention, there is provided an arrangement for supplying an indication to a driver of a vehicle to change to a higher transmission ratio, comprising control means for providing a signal, in response to engine load and rotational speed, representing unfavourable fuel consumption, and means for providing the indication to the driver in response to the signal.

It is thus possible to provide an arrangement for providing a gear-change indication which gives to the driver of a motor vehicle unequivocal and easily processable information for the guidance of his driving behaviour, without impairing his attention to traffic.

In a preferred embodiment of the present invention, an operating range of the engine unfavourable to fuel consumption is determined as a function of the temperature and of the engaged speed, which is limited by an operating line injection time as a function of the engine rotational speed, and a shifting-up signal is produced when the operating point of the engine lies within this fuel unfavourable operating range.

The operating range of the engine which is unfavourable with respect to the fuel consumption is thereby calculated by a control apparatus, which produces as its computing result an optical or acoustic indicating signal at an indicating apparatus in order to inform the driver of the vehicle that he can leave the uneconomical operating range by shifting up. It is thus possible for the driver to operate a motor vehicle engine in an economic manner without being distracted from the road traffic.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a schematic block diagram of a shifting arrangement constituting a preferred embodiment of the present invention; and Figure 2 is a flow chart for carrying out computer functions.

Referring now to the drawings wherein like reference characters are used throughout the two Figures to designate corresponding parts, and more particularly to Figure 1, a pick-up or transmitter 1 for the engine rotational speed n, a pick-up or transmitter 2 for the vehicle velocity v, a pick-up or transmitter 3 for the injection time ti, and a pick-up or transmitter 4 for the cooling water temperature v are connected to a control apparatus generally designated by reference numeral 5 whose operation is in accordance with the flow chart illustrated in Figure 2 and which controls an indicating apparatus 6.A first comparator step 7 (Figure 2) of the control apparatus 5 determines whether the measured injection time ti is smaller than a predetermined minimum injection time time. If this is the case, then a vehicle coasting operation exists and the arrangement for the shifting-up indication is not rendered operative, i.e. the indication is deenergized. If, in contrast, ti is larger than tri,,,, then the measured characteristic magnitudes are supplied to a calculating step 8 which forms the quotient of the engine rotational speed n and driving velocity vand multiplies the quotient by a factor 2X to give n K=- 2x.

v The exponent x has a value of about 4 or 5 depending on the type of transmission and on the types of pick-ups 1 and 2. The multiplication by the factor sX is necessary in order to increase, from a computational point of view, the transmission ratios which, for example, amount to 2.35; 2.90; 3.20, in such a manner that values which can be distinguished from one another by integers will result ahead of the decimal point.

The output K-value of the calculating step 8 is now supplied to a chain of comparator steps 9, 10, 11, 12 .... The comparator step 9 determines whether K is larger than K1, where K1 has a value of, for example, 1 10; if this is the case, then error information is present since no transmission ratio corresponds to such a high K-value. If K is smaller than Ski, then the value of K is supplied to a comparator step 10 for determining whether K is larger than K2 with a K2-value of, for example, 95. If this condition is fulfilled, it is indicated that the first gear ratio or speed is engaged at that instant in the transmission 22; this transmission speed G 1 is supplied together with the temperature to a step 14 for forming nG=f(G, v).

The value from this step is supplied to a comparator step 1 5 for determining whether n is larger than nG. If the answer is affirmative, then a step 1 6 forms the function tiG=f(nG, n) and the output value is supplied to a comparator step 17 for determining whether ti < tiG. If both conditions n > n5 and ti < tiG are fulfilled, then a control command is produced to the indicating apparatus 6 for providing shifting-up or change-up signal.

If it is determined in the comparator step 10 that the condition K larger than K2 is not fulfilled, then the comparator step 11 for determining whether K is larger then K3 is next performed. If, for example, K3 is selected to be equal to 60 in the step 11 and the comparison is answered in the affirmative, then again error information is present, i.e. an intermediate value between first and second speed or gears which does not exist in the transmission. A K-value corresponding to the second speed is determinable only by means of the comparator step 1 2 for determining whether K is larger than K4 with a K4-value of, for example, 40. If this condition is fulfilled, then the information: second speed or gear is engaged, is supplied to the step for forming dG=f(flG, v).As described hereinabove, after passing through the steps 15, 16, 17, a shifting-up change-up indication is turned on; if the answer is negative in the step 1 5 and in the step 17, the shifting-up indication is turned off. In a similar manner, if the second speed or gear is not engaged, for example, with a five-speed transmission, the further speeds or gears 3 and 4 are tested in corresponding comparator steps. With a positive result, information about the engaged speed is fed to the step 14. If none of the speeds or gears 1 to 4 is recognised, the indication is turned "off" by way of the comparator step 13.

The diagram of injection time ti as a function of the engine rotational speed n is used in the apparatus consists of an upper line 18 (Figure 1) and of an operating line 19. The upper line 18 corresponds to a fuil load curve. The operating line 19, which is formed of a vertical branch extending parallel to the ordinate and of a branch increasing with rotational speed, limits the fuelfavourable range 20 disposed thereabove from the fuel-unfavourable range 21.The operating values are indicated by tiG and nG, while the injection time coordinated to the corner point of the two branches is indicated by tieck The configuration of the operating line 1 9 is selected so that after shifting-up a sufficient accelerating reserve is still present in each speed and at each velocity so that a fuel saving is possible by intentionally shifting-up without limitation of the individual manner of driving conditioned by traffic.

To indicate shifting-up, an arrow lights up in the indicating apparatus 6 within the field of vision of the driver. In order to avoid continuous flashing of the arrow under limit conditions, the signal is produced only after a predetermined deiay period which can be preselected.

Additionally, by widening the operating line 1 9 into a band with an inner line 19' and an outer line 1 9", shifting hysteresis is provided. During passage from the fuel-unfavourable range 21 to the fuel-favourable range 20, the outer line 1 9" becomes effective as shifting line whereas during passage in the reverse direction the inner line 19' becomes effective as shifting line.

Claims

1. An arrangement for providing an optical or acoustic indication for notifying a driver of a motor vehicle optically or acoustically to drive an engine of the vehicle in a more economical range by changing to a higher transmission speed by providing a signal determined as a function of measured characteristic magnitudes comprising vehicle velocity, engine rotational speed, load or injection time, and cooling water temperature which is supplied to a control apparatus, in which a fuel-unfavourable operating range of the engine is determined as a function of the temperature and of the engaged speed, which is limited by an operating line injection time as a function of the engine rotational speed, and in which a changingup signal is produced when the operating point of the engine lies within the operating range.

2. An arrangement as claimed in claim 1, in which pick-ups for the engine rotational speed and vehicle velocity are connected to the control apparatus which is arranged to form the quotient of the rotational speed and the velocity and to provide the changing-up signal in response to comparison with predetermined limit values coordinated to transmission ratios of the vehicle transmission.

3. An arrangement as claimed in claim 2, in which for the respectively engaged transmission speed the rotational speed limit value is calculated or taken from a storage device, injection limit value dependent on the rotational speed limit value for increasing rotational speed is calculated or taken from a storage device, and by comparison of the measured rotational speed and injection periods with the respective limit values it is determined whether the engine operating point lies in a fuel-favourable range.

4. An arrangement as claimed in any one of claims 1 to 3, in which, after reaching the limit value, the changing-up indication takes place only after a predetermined time delay.

5. An arrangement as claimed in any one of claims 1 to 4, in which the operating line comprises a band with an inner line and an outer line, and in which during passage from the fuelunfavourable range to the fuel-favourable range, the outer line is effective as boundary line whereas, during passage from the fuelfavourable range to the fuel-unfavourable range, the inner line is effective as boundary line.

6. An arrangement as claimed in any one of claims 1 to 5, in which the configuration of the operating line is changeable during the operation corresponding to the respective engaged transmission ratio.

7. An arrangement as claimed in any one of claims 1 to 6, in which the operating line as a function of load against engine rotational speed is composed of a vertically rising branch and of a branch increasing with rotational speed and is shaped so that, after a change-up signal has occurred, at least as good an acceleration capability of the motor vehicle exists as prior thereto.

8. An arrangement as claimed in any one of claims 1 to 7, in which a clutch of the vehicle disengaged, the indication is suppressed, disengagement of the clutch being detected by a predetermined number of computing operations in which no valid transmission ratio is recognized.

9. An arrangement as claimed in any one of claims 1 to 8, in which means for providing the change-up indication comprises a transparent light mark which is located at the wind-screen of the motor vehicle and which is self-illuminated or is caused to light up by radiation from a light source.

10. An arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

11. An arrangement for supplying an indication to a device of a vehicle to change to a higher transmission ratio, comprising control means for providing a signal, in response to engine load and rotational speed, representing unfavourable fuel consumption, and means for providing the indication to the driver in response to the signal.

12. An arrangement as claimed in claim 11, in which the control means is arranged to receive engine temperature signals or injection timing signals representing engine load.

13. An arrangement as claimed in claim 11 or 12, in which the indication-providing means is a two-state device having a first state providing the indication and a second "off" state.