JPH0261690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for monitoring the fuel consumption of a motor vehicle, and in particular to a device for monitoring the fuel consumption of a motor vehicle, in particular, data characteristic of the motor vehicle fixedly stored in an electronic storage device of the evaluation circuit, and fuel consumption data that can be input to the evaluation circuit. and processing data characteristic of the operating state of the vehicle's drive system to generate an output signal that correlates with the vehicle's instantaneous fuel consumption, and when the driver selects another gear. The present invention relates to a device for monitoring the fuel consumption of a motor vehicle, in particular a commercial vehicle, with a transmission, comprising an evaluation and display device that can be controlled to generate an display signal providing information on the fuel utilization expected of the vehicle.

This type of device is necessary in commercial vehicles, which have a low-power engine compared to passenger cars, but which have a fairly large number of gears, for example 16 gears, in order to be able to make good use of the engine power. be. Assuming that these gears are in a normal phase, for example a so-called geometric phase, the same propulsion force is obtained in many gears despite the different utilization of fuel.

The purpose of a device of the type mentioned in the introduction to this specification is to provide the driver with a speed change in which the engine is operated in the most advantageous efficiency range in a given driving situation with a view to minimizing fuel consumption. The purpose is to provide a decision aid that allows an optimal selection of stages. Known devices of the type mentioned in the introduction to this specification are provided with a rotary display for analog-wise display of the instantaneous consumption of fuel. In this display device, the high and low consumption ranges are indicated by different colors on the display scale to indicate diseconomies or increasing economies. Furthermore, this known device contains fixedly stored characteristic data of the engine and variable data such as the position of the accelerator pedal as a parameter correlated with the instantaneous consumption and as a parameter characteristic of the operating state of the engine or of the vehicle. A reduction in fuel consumption in the operating state of the engine or vehicle caused by the driver looking at the consumption display and shifting higher or lower gears, in conjunction with the engine speed and vehicle speed. A microprocessor is provided which generates an indication signal to the driver that this has been achieved. Despite the very significant fuel savings achieved when the driver presses the accelerator pedal as "sparingly" as possible in accordance with the consumption indication and therefore also follows the gear change recommendation signal given as an optical signal, this known device , the persistent display of instantaneous fuel consumption, which is important for economical driving but cannot be determined by itself, may lead drivers, especially consumption-conscious drivers, to mistakenly overestimate the significance of this quantity. higher engine performance (engine power) for acceleration or maintaining constant vehicle speed
As a result, commercial vehicles generally have to maintain a small output, resulting in lower driving performance (vehicle output) and increased driving time. This often results in poor overall economic utilization of the vehicle, despite fuel savings.

Furthermore, in this known device, the savings achieved by following a gear shifting recommendation presented to the driver in the form of an accept/no offer is only evaluated when the driver actually shifts gear. Ru.
On the one hand, this saving effect is often very small, but on the other hand, shifting gears, for example while driving in the mountains, results in a large change in vehicle speed and the fuel has to be consumed again in order to reach the possible more advantageous consumption range. Compliance with shifting recommendations often leads to higher overall fuel consumption, as acceleration of the vehicle is required. Furthermore, the device known from DE 29 28 318 has essentially the same drawbacks for obtaining statements regarding the economical or uneconomical operation of a motor vehicle. In this device, a speed change recommendation is given to the driver in the form of a proposal to accept or reject, also by means of an optical signal. However, in this known device there is no quantitative consumption display, so that the driver cannot even reliably check the results of following the shifting recommendations, but at least has no idea of the effectiveness of the recommended shifting strategy. Experience values can be obtained and can be taken into account as an aid to decisions to comply with or contrary to indicated shifting recommendations, as the case may be.

It is therefore an object of the present invention to provide a device of the type mentioned in the introduction to this specification, which not only displays a gear change recommendation to the driver, but also provides quantitative information about the expected fuel consumption when changing gears. It is to obtain.

This object is achieved by the features described in the characterizing part of claim 1.

The device according to the invention thereby displays the difference in fuel consumption that occurs when the driver changes from the currently existing gear to the gear indicated by the call signal sent to the evaluation circuit. From the display of this difference in fuel consumption, given in digital or analogue form, the driver can decide whether to change gears, for example, because the reduction in consumption that can be achieved is so large that after a short time this change is not possible due to traffic conditions or when the road is uphill. Direct recognition of whether it makes sense, even though it is foreseen that it will have to be resolved at some point, or whether this gear change remains unperformed because the expected fuel savings are small. .

It is particularly advantageous if the evaluation circuit can be controlled by a simultaneously displayed high or low shift recommendation signal of the shift recommendation signal generator. In such an arrangement of the device according to the invention, the consumption indication signal is generated and displayed only when a fuel saving is actually also achieved by switching in the direction given by the respective gearshift recommendation.

Further embodiments of the evaluation circuit of the monitoring device according to the invention are provided by the features of claims 3 and 4. In this case, the speed change recommendation output signal of a known speed change recommendation signal generator of any configuration can be used for control that meets the purpose of the evaluation circuit.

The features of claim 5 provide one configuration of the evaluation circuit, which itself is also used as a gear change recommendation signal generator.

The device according to the inventive concept includes an input device in addition to or as a variant of the gear change recommendation signal generator, as given by claim 6. This input device allows the driver to determine the consumption difference for a currently existing gear for any gear of the transmission.

The device 10 for monitoring fuel consumption according to the invention, shown generally in FIG. 1 and in detail in FIGS. 2 or 4, is designed for motor vehicles which are also equipped with a shift recommendation signal generator 11. Without losing generality, the automobile shown in FIG. 1 with only a drive train including an engine 12, a clutch 13, a transmission (transmission gear) 14, and a drive shaft (propeller shaft) 16 is a heavy utility vehicle (commercial vehicle). Assume that It is assumed that the transmission 14 has 16 gears of geometrically or approximately geometrically different grades.

With such a fine grade of transmission 14 and the typical design of engine 12, a constant power output of the engine or a plurality of gears, for example three, may be used or provided to provide the desired operating performance. However, the fuel consumption in terms of unit time and/or reference distance can vary widely by means of different possible gears.

The purpose of the shift recommendation signal generator 11, whose configuration and function are assumed to be known, is to determine at which gear of the transmission 14 a desired engine output or vehicle output can be obtained with the lowest possible fuel consumption. The purpose of this is to generate a display signal to notify the driver that this is the case. The shift recommendation signal generator generates this indication signal from appropriate processing of stored engine characteristic data and measured engine operating data.

It is further an object of the device 10 of the present invention to obtain an indication of possible fuel savings when following shifting recommendations;
Thereby, when this consumption is high, an increase (H) is signaled to the driver by the gear shift recommendation signal generator 11.
This is to provide an additional stimulus in accordance with one of the gear shift recommendation and the down (R) gear shift recommendation. Such an additional incentive provided by the indication of a high potential for savings is in particular within the "expected distance", i.e. within the visible or otherwise known distance and/or in traffic situations. This is necessary when the driver first decides not to change gears.

The central functional element of the device 10 according to the invention is the evaluation circuit 17. This is microcomputer 18
Drive trains 12, 13, 14, 1 stored in
6. In particular, characteristic data of the engine 12 and the transmission 14 and information about the operating state of the engine 12 and the switching state of the transmission 14 that are continuously provided to the microcomputer 18 and the transmission recommendation signal generator 11. From suitable electronic processing with variable data containing information about the most advantageous gear for consumption, the driver follows the H or R gear recommendation signaled by the gear recommendation generator 11. generates an output signal that is less consuming than that which occurs when

Next, using FIGS. 1-3, the monitoring device 10 of the present invention will be described.
The first embodiment will be explained in detail.

In this embodiment, the microcomputer 18 permanently stores a group of characteristic curves of the automobile engine 12 shown in FIG. 3 in a tabular or analytical format. This characteristic curve group 19 shows the relationship between engine torque M and engine rotational speed n. The abscissa in Figure 3 is the engine rotation speed n, which is the maximum rotation speed n _nax
The ordinate represents the engine torque M in the ratio M/M _nax to _the maximum torque M _nax . This characteristic curve group 19 under the full load curve 21
Each point corresponds to an engine power proportional to the product of the abscissa and the ordinate. The curve branches 22-30, which run approximately parabolically below the full load curve 21, represent operating conditions with the same temporal fuel consumption. The lower left curve 22 indicates a very low fuel consumption, e.g. 10l/
The uppermost right-hand curve branch 30 represents an operating state of high fuel consumption, for example 80 l/h.
Each torque/rpm pair or power value of engine 12 is therefore also uniquely associated with a particular fuel consumption value. This can be determined from the characteristic curve group 19 when the engine torque and rotational speed are known. Similarly, if the instantaneous consumption Q _i of the engine and its rotational speed n are known, the associated engine torque can also be determined from characteristic curve group 19. At this time, it is assumed that the maximum torque M _nax and the maximum rotational speed n _nax of the engine 12 are known.

As variable data, the evaluation circuit 17 receives the following measured quantities in a format suitable for digital processing in the microcomputer 18: 1 Instantaneous fuel consumption Q _i of the engine 12 . This is simply converted into a digital measurement signal, for example by means of a small axial turbine or an oval gear flow meter.

2 Engine speed n. This is preferably detected by an inductive pulse generator located in the area of the toothed rim of the flywheel of the engine.

3 The current gear ratio i of the transmission 14. This can be determined by a suitable measurement of the gearshift output speed and its comparison with the engine speed n or by electrical detection of the gearshift lever position and can be converted into a characteristic digital signal.

4 Output signal i _H/R of the speed change recommendation signal generator 11. This is also a suitable digital format, high (H)
Alternatively, the optimum gear shift for the lowest possible fuel consumption should be selected by switching to low (R).

These inputs are processed in the microcomputer together with the characteristic data of the engine 12 of FIG. 3 stored therein as follows: In a first processing stage 31, the instantaneous consumption measurements are
The engine torque (M) is determined using the characteristic group data stored from Q _i and the rotational speed n of the engine 12. In the second processing stage 32, the torque M obtained when the driver follows the above-mentioned shift recommendation, with the subcondition that the engine output should be the same as before according to the shift recommendation of the shift recommendation signal generator 11. _H/R and engine rotational speed n _H/R are determined. These two quantities are determined in this second processing stage by the relationships M _H/R = i/i _H/R ×M (1) and n _H/R = i _H/R /i×n (2) be done.

From these two quantities, in the third processing stage 33, the fuel consumption associated with the value pair M _H/R , n _H/R is determined using again the stored data representing the characteristic curve group 19.
Q _H/R can be determined. Finally, in a fourth processing stage 34, by subtracting this calculated consumption Q _H/R from the measured value Q, an output signal is generated which is related to the consumption difference ΔQ. This output signal directly corresponds to the achievable fuel savings per unit time and is displayed to the driver in digital or analog form on a display device 36, for example in l/h. This display device 36 can further be provided with a division stage 37 . This divider stage generates an output signal proportional to the ratio ΔQ/Q from the quotient of the ΔQ output signal of the fourth processing stage 34 and the output signal of the consumption measuring device, indicating the fuel savings in percent. Finally, engine speed n
and the speed ratio i of the transmission 14, and the time-related consumption difference signal ΔQ of the processing stage 34, obtained by dividing the time-related consumption difference signal ΔQ, by a signal proportional to the vehicle speed to generate a consumption difference signal related to the traveling distance. Can be done. This consumption signal is displayed on the display device 36 at l/100Km.
It is preferable to display it in units of .

The embodiment of the monitoring device 10 according to the invention, which will be described again in terms of function below with reference to FIGS. 1 and 4-6, is particularly designed for use in motor vehicles with diesel engines and is similar to that described above. differs essentially in that the fuel consumption characteristic input to the microcomputer 18 is obtained from a measurement of the stroke RW of the control rod of the injection pump. Other inputs n, i, i _H/R are the same as in the embodiment described using FIGS. 1 and 2.

Further different from this embodiment, the microcomputer 18 has a characteristic curve group 38 shown in FIGS.
39 is fixedly stored analytically or in the form of a table, and the relationship between the engine torque M and the engine rotation speed n is reproduced using a normalized display of the characteristic curve group 38 corresponding to the display of the characteristic curve group 19 in FIG. do. Curve group 38
The operating conditions are represented by the curves 41-47 at the same control rod path. Bottom curve 4 in Figure 5
1 typically corresponds to a control rod travel of, for example, 5 mm, and the full load curve 48 corresponds to a control rod travel of 11.5 mm. Same control rod length RW between curves 48 and 41
Curves 42-47 correspond to step increases in control rod travel of 1 mm, respectively.

The characteristic curve group 39 in FIG. 6 reproduces the dependence of the fuel consumption Q on the control rod length. The horizontal axis (abscissa) is the control rod travel RW/RW _nax normalized to the maximum control rod travel RW _nax , and the vertical axis is the maximum consumption Q _nax
is the fuel consumption Q/Q _nax normalized to The fuel consumption curves 51-59, which are approximately linear and result in a full load curve 49, each show the dependence at a constant engine speed. In the typical case observed, the lowest consumption curve 51 corresponds to an engine speed of 600 rpm and the highest curve 59 to a speed of 2200 rpm.

fixedly stored in the microcomputer 18,
Processing of data represented by characteristic curve groups 18 and 19 and variable inputs was performed as explained using FIG. 4.

In a first processing stage 61, the engine torque is determined from the measured control rod travel value RW and the engine speed n, taking into account the data stored for the characteristic curve group 38. In the second processing stage 62, the engine torque M _H/R and rotational speed are determined under the same conditions and under the same operation as explained using FIG.
n _H/R is determined. This occurs when the driver complies with the shift recommendations signaled by the shift recommendation signal generator 11. In the third processing stage 63, the stored data of the characteristic curve group 38 is used again to create a pair of values.
The control rod path RW _H/R associated with M _M/R and n _H/R is determined. In a fourth processing stage 64, the fuel consumption Q and Q H/R for the value pairs RW,n and RW _H/R ,n _{H/R are} determined using the stored data of the characteristic curves 39 characteristic of the engine _{. R} can be determined. These represent the consumption Q before the shift recommendation and Q _H/R after the shift recommendation is followed, respectively. From the consumption values obtained on the one hand by measurement and on the other hand by calculation in the microcomputer 18, a consumption difference signal ΔQ used for display is finally generated in the final processing stage 65.

FIG. 7 shows the basic configuration of another embodiment of the device 70 of the present invention. This example is based on that of Fig. 1.
The evaluation circuit 71 not only generates a consumption difference display signal to help the driver make a decision, but also generates a gear change recommendation signal indicating the optimum gear ratio for the driver. The present invention is essentially different in that it also satisfies the function of the speed change recommendation signal generator 11 shown in FIG. 1 when combined with a circuit device. Functional elements of device 70 of FIG. 7 that are functionally the same or similar to those of device 10 of FIG. 1 are provided with the same reference numerals.

The microcomputer 18 of the evaluation circuit 71 receives at a first input 72 an input signal characteristic of the instantaneous fuel consumption, for example the output signal of a fuel flow meter or the output signal of a control rod path monitoring device, and at a second input 73 an input signal characteristic of the instantaneous fuel consumption. receives an input signal characteristic of a rotational speed n. A third input 74 of the microcomputer 18 is supplied with an input signal characteristic of the gear position of the transmission 14 corresponding to the gear ratio i. A fourth input 76 and a fifth input 77 are supplied with the output signal of an interrogation signal generator 78. The interrogation signal generator 78 is provided in place of the gear change recommendation signal generator so that the evaluation circuit 71 instructs the gear position to generate a consumption difference output signal for the current gear position.

In this embodiment, the interrogation signal generator 78
A first partial circuit 79 generates interrogation signals indicative of higher and lower gears than the current one in a time-controlled cyclic sequence; A second partial circuit 81 is thus able to generate an interrogation signal indicating any gear higher or lower than the current one. These two sub-circuits are respectively connected to a fourth input 76 of the microcomputer 18 and a first output 8 as shown.
4 and 86, an interrogation signal indicating a higher gear of the transmission 14 than the current one is generated, and the second outputs 87 and 88, which are connected to the fifth input 77 of the microcomputer 18, each have a higher gear than the current one. An interrogation signal indicating a lower gear is configured to be generated.

The processing of these input signals takes place in the microcomputer 18 in the manner described in detail with reference to FIGS. An output signal for reproducing the target consumption Q _i is generated, and its second and third outputs 91 and 92 respectively have
An output signal is generated which reproduces the expected fuel consumption Q _iH or Q _iR when the driver selects the gear indicated by the interrogation signal of the first or second subcircuit 79 , 81 .

A comparison circuit 93 is provided as an output stage of the evaluation circuit 71. The latter determines, from a comparison of the output signals Q _i , Q _iH , Q _iR of the microcomputer 18 which are proportional to these consumptions, a threshold value at which the lower consumption associated with the gear selection described below can be determined. When exceeded, a shift recommendation signal is generated favoring the gear for the lowest consumption.

This comparator circuit 93 comprises a first comparator stage 44 which receives as a first input signal the Q _i instantaneous consumption signal of the microcomputer 18 or possibly the flow meter and as a second input signal the Q _iH output signal of the microcomputer 18. and the same as the first input signal
a second receiving the Q _i instantaneous consumption signal and the Q _iR output signal of the microcomputer 18 as a second input signal;
and a comparison stage 96. The Q _iR output signal is the degree of fuel consumption when shifting to a lower gear. Comparison stage 9
4 and 96 are the differences ΔQ _iH = Q _i −Q _iH and ΔQ _iR = Q _i
−Q Generates an output signal proportional to _iR . These signals are each proportional to the lower or higher consumption achieved by shifting (gear shifting), depending on which of the consumption values is greater. Each time the consumption difference output signal of one or the other of the comparator stages 94, 96 signals a small consumption amount (signals to reduce the consumption amount) when the consumption amount exceeds the above threshold value, this small consumption is The amount is displayed on the display device 36.
is displayed in an appropriate unit on the display window 97 or 98. At the same time, a display window 99 or 101 is associated with a corresponding high or low gear shift recommendation for the driver.
will be displayed. A third display window 102 can also be provided for displaying the instantaneous consumption Q _i .

Advantageously, the use of the evaluation circuit 71 for generating the gear change recommendation signal in the device 70 simplifies the overall construction.

A common advantage when using the devices 10, 70 of the invention as described above is that the display signal that attracts the driver's attention is activated when a significant reduction in consumption is achieved by changing gears or when the driver receives an interrogation signal. The reduction in consumption achieved is expressed very accurately as a difference in consumption.

[Brief explanation of drawings]

FIG. 1 is a highly simplified schematic diagram showing the basic structure of a device for monitoring fuel consumption according to the invention. FIG. 2 is a simplified block diagram of a first embodiment of an evaluation circuit for generating a fuel consumption signal used in the apparatus of FIG. FIG. 3 is a group of characteristic curves showing the relationship between engine torque and engine speed at various fuel consumptions over time, in order to explain the function of the evaluation circuit of FIG. FIG. 4 is a simplified block diagram of a second embodiment of an evaluation circuit for generating a fuel consumption signal using the device of FIG. 5 and 6 show, respectively, the relationship of the engine torque to the engine speed at various values of the control rod stroke of an injection pump of an automobile with a diesel engine and various values for explaining the functioning of the evaluation circuit of FIG. 2 is a group of characteristic curves showing the relationship between fuel consumption and control rod travel at engine speeds of . FIG. 7 is a diagram corresponding to FIG. 1 of another embodiment of the device of the invention. 10, 70... Fuel consumption monitoring device, 11... Shift recommendation signal generator, 12... Engine, 13...
Clutch, 14...Transmission device, 16...Drive shaft,
17, 71...Evaluation circuit, 36...Display device, 7
8...Question signal generator, 93...Comparison circuit.

Claims (1)

[Scope of Claims] 1. Vehicle-specific data fixedly stored in the electronic storage device of the evaluation circuit; and data characteristic of fuel consumption and the driving state of the vehicle's drive system that can be input to the evaluation circuit. an evaluation that generates an output signal correlated with the vehicle's instantaneous fuel consumption from processing with a display signal that provides the driver with information regarding expected fuel utilization when selecting another gear. device for monitoring the fuel consumption of a motor vehicle with a manual transmission, comprising a display device and a display device, the evaluation circuit 17; 71 being controllable with a call signal indicating the gear ratio to be taken into account when changing gears; The response signal generated in the evaluation circuit 17; 71 is then determined to reduce fuel consumption when changing from the current gear to the gear indicated by the respective call signal, when the engine power is constant. A monitoring device characterized in that it is provided with a display device 36 which indicates whether the consumption difference is increased or increased and further displays a response signal proportional to the consumption difference in an appropriate unit. 2. Gear stage (gear ratio) that makes optimal use of fuel
According to claim 1, the evaluation circuits 17 and 18 can be controlled by the speed change recommendation signal from the speed change recommendation signal generator 11. monitoring equipment. 3. The evaluation circuit 17 includes a fuel flow meter that generates an electric output signal correlated with instantaneous fuel consumption and a rotation speed signal generator that generates an electric output signal proportional to the engine rotation speed. When the gear change recommendation is followed from the processing of the measured values of consumption Q _i and engine speed n, and the stored data 19 including the relationship characteristic of the engine between the engine torque M and these measured values. Claim 1, characterized in that a low fuel consumption (reduction in consumption) indication signal is generated by comparing an output signal correlated with fuel consumption expected for a fuel flow meter with an output signal of a fuel flow meter. monitoring equipment. 4. A signal characteristic of the instantaneous fuel consumption is obtained from monitoring the position of the control rod of the fuel injection pump, and the evaluation circuit 17; A first output signal proportional to the instantaneous fuel consumption from the processing of the measured values and stored data including an engine-specific relationship between the engine torque and a second output signal proportional to the fuel consumption when following the shifting recommendation. the output signal from the first and second
2. A monitoring device according to claim 1, wherein a consumption reduction output signal is generated from a comparison of the output signals. 5. The evaluation circuit 71 determines, in subsequent test cycles, a first signal proportional to the consumption characteristic of the current gear i of the transmission 14 and the fuel consumption when the next higher gear i _H is present. a proportional second signal;
a third output signal proportional to the fuel consumption when a lower gear stage i _R is present, and a shift recommendation signal favoring the lowest consuming gear stage from a comparison of these consumption-proportional signals; Claim 1-- characterized in that a comparator circuit 93 is provided, which occurs when the resulting reduced consumption exceeds a predeterminable or predetermined threshold.
The monitoring device according to any of Item 4. 6. Monitoring device according to any of claims 1 to 5, characterized in that it is provided with an input device 78 with which an interrogation signal relating to possible gears can be input into the evaluation circuit 71. 7. The monitoring device according to any one of claims 1 to 6, wherein the display device 36 displays the difference in fuel consumption in units of l/100Km. 8. The monitoring device according to any one of claims 1 to 6, wherein the display device 36 displays the difference in fuel consumption as a percentage of fuel consumption with respect to the currently existing gear position.