Method and device for displaying engine speed of internal combustion engine

Abstract

To solve the problem that when, after idling stop, a restart request is made before the rotation of a crankshaft is completely stopped, and the display of a pseudo rotation speed N3 is ended, an engine speed to be displayed is increased to cause uncomfortable feeling.SOLUTION: A tachometer 21 displays a first rotation speed N1 based on a crank angle sensor signal during traveling, and it displays a filtered second rotation speed N2 during idling. When idling stop begins (time t1), the tachometer 21 displays a pseudo rotation speed N3, and shows 0 before the rotation of a crankshaft is completely stopped. When a restart request is made, the tachometer continuously displays 0 using the pseudo rotation speed N3 until it is determined that an internal combustion engine is operated (time t4).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for displaying the rotation speed of an internal combustion engine on a tachometer of a vehicle equipped with an idling stop function. [Background technology]

[0002] The rotation speed of an internal combustion engine is generally calculated based on the time intervals of pulse signals from a crank angle sensor output at regular crank angle intervals. In a vehicle equipped with an idling stop function, the time intervals of the pulse signals become longer as the rotation speed decreases during idling stop, resulting in a significant delay before it is determined that the rotation speed has reached zero, which can lead to an unnatural display on the vehicle's tachometer. Patent Document 1 therefore discloses a method for calculating a virtual rotation speed that reaches zero according to a predetermined characteristic, and switching the rotation speed display on the tachometer to this virtual rotation speed when an idling stop condition is met. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-031775 Summary of the Invention [Problem to be solved by the invention]

[0004] After the idle-stop condition is satisfied and fuel injection and ignition of the internal combustion engine are stopped, it takes a certain amount of time, although it is relatively short, for the rotation of the crankshaft to completely stop. During this time, if the idle-stop condition is no longer satisfied, for example, because the driver releases the brake pedal, a restart of the internal combustion engine is requested, and at the same time, the rotation speed display on the tachometer switches from displaying a virtual rotation speed (which is 0 during idle-stop) to displaying a rotation speed based on the pulse signal from the crank angle sensor. Therefore, before the rotation of the crankshaft has completely stopped, the rotation speed displayed on the tachometer suddenly rises from 0, causing a sense of discomfort to the driver. In other words, the rotation speed displayed on the tachometer temporarily increases even though the internal combustion engine has not yet been restarted, creating a sense of discomfort. [Means for solving the problem]

[0005] The present invention provides a method for displaying the rotation speed of an internal combustion engine for a vehicle equipped with an idling stop function on a tachometer of the vehicle, comprising: determining a first rotation speed each time a pulse signal is input based on a time interval between pulse signals of the crank angle sensor; The first rotation speed value outputted in a discrete manner is filtered for smoothing to obtain a second rotation speed; displaying the second rotation speed on the tachometer while the vehicle is idling while stopped, and generating a pseudo rotation speed signal that is pseudo to 0 when the vehicle is idling stop, and displaying the pseudo rotation speed signal on the tachometer; After the internal combustion engine has started to be restarted from the idling stop state, the pseudo rotation speed signal continues to be displayed until it is determined that the internal combustion engine is in operation.

[0006] For example, even if the brake pedal is released immediately after the engine has entered an idling stop state to initiate a restart, the pseudo RPM signal will cause the tachometer to remain at 0 until the internal combustion engine actually starts and is determined to be operational. If the engine were idling immediately after start-up, the display would transition to the second RPM, but at this stage the internal combustion engine has already restarted, so the driver will not feel uncomfortable. [Effects of the Invention]

[0007] According to this invention, it is possible to avoid the phenomenon in which the rotation speed displayed on the tachometer temporarily rises when the idle stop conditions are not met due to, for example, the brake pedal being released before the rotation of the crankshaft completely stops after the idle stop has started. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating the configuration of a vehicle to which an engine speed display according to an embodiment of the present invention is applied; [Figure 2] 4 is a time chart showing the operation of an embodiment from the start of idling stop to restart. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows the configuration of a drivetrain for a vehicle according to the embodiment. The embodiment is a rear-wheel drive vehicle, with an internal combustion engine 1 connected to a stepped automatic transmission 2, and the output of this transmission 2 drives drive wheels 4 via a final drive unit 3. A vehicle equipped with the internal combustion engine according to the embodiment is equipped with a so-called idling stop function, which automatically stops the internal combustion engine 1 when predetermined idling stop conditions are met, such as when the vehicle is stopped temporarily at an intersection, with the vehicle speed at zero, the accelerator pedal released (idle switch ON), and the brake pedal depressed (brake switch ON). In other words, fuel injection and ignition are stopped in response to a stop command for the internal combustion engine 1, and the crankshaft rotates due to inertia for a short period before coming to a complete stop. Then, in the idle stop state, if any of the predetermined cancellation conditions, such as the brake pedal being released (brake switch OFF), a drop in battery SOC, or the accelerator pedal being depressed (idle switch OFF), is met, a restart request is output and the internal combustion engine 1 is restarted via the starter motor 5. The automatic transmission 2 includes a torque converter, which allows automatic stopping and restart when the vehicle is stopped while keeping the automatic transmission 2 in what is called D range.

[0010] The internal combustion engine 1 is equipped with a crank angle sensor 7 for detecting the rotation speed. The crank angle sensor 7 is a typical crank angle sensor that includes, for example, a disc-shaped signal plate provided at the end of the crankshaft and a pickup that detects the passage of protrusions formed at equal angular intervals on the outer periphery of the signal plate. The crank angle sensor 7 is configured to output a pulse signal shaped into a rectangular wave, i.e., a crank angle sensor signal, for each unit crank angle of, for example, about 6 to 10° CA.

[0011] The internal combustion engine 1 is, for example, a spark-ignition internal combustion engine, or so-called gasoline engine, and is controlled by an on-board controller 11. The controller 11 receives detection signals directly or via other controllers from numerous sensors, including the crank angle sensor 7, an air flow meter 12 for detecting the intake air amount, a water temperature sensor 13 for detecting the coolant temperature, an air-fuel ratio sensor 14 for detecting the exhaust air-fuel ratio, a throttle valve position sensor 15 for detecting the throttle valve position, an accelerator pedal position sensor 16 for detecting the accelerator pedal position operated by the driver, a brake switch 17 for detecting the brake pedal depression, and a vehicle speed sensor 18 for detecting the vehicle speed. Based on these detection signals, the controller 11 optimally controls the fuel injection amount and injection timing of the fuel injection valve, the ignition timing of the spark plug, the throttle valve position, and the like. The controller 11 also executes the above-mentioned idling stop and restart. The throttle valve position sensor 15 also functions as an idle switch, determining that the vehicle is idling when the throttle valve is fully closed.

[0012] Furthermore, the controller 11 calculates the rotation speed of the internal combustion engine 1 based on the pulse signal (crank angle sensor signal) output by the crank angle sensor 7, and displays this rotation speed on the vehicle's tachometer 21. The tachometer 21 may be of any type, such as an analog type with a rotating needle, a digital type that displays the rotation speed discretely by lighting up multiple segments, or a digital type that displays numerical values.

[0013] Next, the rotation speed displayed on the tachometer 21 will be described. Each time a pulse signal is input from the crank angle sensor 7, the controller 11 calculates a basic first rotation speed based on the time interval between the previous pulse signal and the current pulse signal. During normal running other than idling, this first rotation speed is displayed on the tachometer 21. Note that the first rotation speed becomes 0 if the next pulse signal is not input within a predetermined waiting time.

[0014] The controller 11 also performs filtering on the discretely output first rotation speed value to smooth it and calculate a second rotation speed. The filtering can be, for example, a first-order lag filter, but other types of smoothing filters may also be used. During idling, when the actual rotation speed of the internal combustion engine 1 is low, the second rotation speed is displayed on the tachometer 21. This allows the meter display to be provided with small fluctuations in the actual rotation speed during idling removed. For example, when the vehicle shifts from a running state to a stop and an idling state, the display on the tachometer 21 switches from the first rotation speed to the second rotation speed. The calculation of the second rotation speed by filtering may be performed only during idling, or may be performed constantly in the background.

[0015] The controller 11 also has a function of generating a pseudo rotation speed signal to display the rotation speed at the start of idling stop. The pseudo rotation speed signal is generated so that it changes from the displayed rotation speed (first rotation speed or second rotation speed) at the start of idling stop to 0 with a predetermined decrease characteristic and maintains 0 during idling stop. The initial decrease characteristic may be a linear characteristic with a substantially constant gradient (rate of change) or a curved characteristic with a varying gradient. However, this decrease characteristic is set so that the pseudo rotation speed reaches 0 before the first rotation speed reaches 0 during idling stop. When idling stop conditions are met and idling stop is started, the display on the tachometer 21 is switched from the second rotation speed to the pseudo rotation speed based on this pseudo rotation speed signal. In other words, the display on the tachometer 21 reaches 0 without waiting for the rotation of the crankshaft to completely stop.

[0016] The display of the pseudo rotation speed (i.e., display of 0) on the tachometer 21 continues after the start of restart of the internal combustion engine 1 until it is determined that the internal combustion engine 1 is in operation. If a restart request is issued, for example, by releasing the brake pedal during idling stop, the restart is performed by cranking the starter motor, as described above. Then, the internal combustion engine 1 transitions to so-called independent operation and, for example, reaches a predetermined rotation speed, and it is determined that the internal combustion engine 1 is in operation. When this operation determination is made, the display of the pseudo rotation speed ends and is switched to display of the second rotation speed or the first rotation speed.

[0017] For example, if the brake pedal is released but the throttle valve opening is still 0 and the vehicle is determined to be idling, the second engine speed that has undergone filtering will be displayed. If the accelerator pedal is depressed and the idling stop is released and the vehicle immediately begins to move, the first engine speed will be displayed.

[0018] 2 is a time chart showing the operation of one embodiment from the start of idling stop to restart. Column (a) in the figure shows the first rotation speed N1, second rotation speed N2, and pseudo rotation speed N3 described above. Column (b) shows the ON / OFF state of the idling stop operation flag. When the idling stop conditions are met, the idling stop operation flag is turned ON, and when the idling stop conditions are not met, the idling stop operation flag is turned OFF. Column (c) shows the engine state determination flag, which is turned ON when it is determined that the internal combustion engine 1 is stopped (more specifically, that fuel injection and ignition are stopped) and turned OFF when it is determined that the internal combustion engine 1 is operating.

[0019] In the illustrated example, at time t1, the idling stop condition is met and the idling stop activation flag is turned ON. At substantially the same time, fuel injection and ignition are stopped and the engine state determination flag is turned ON. With this initiation of idling stop, the rotation speed display on the tachometer 21 is switched to displaying the pseudo rotation speed N3. The pseudo rotation speed N3 quickly decreases in accordance with a predetermined decrease characteristic from the rotation speed at the start of idling stop, for example, the value of the second rotation speed N2, and reaches 0 at time t2. Therefore, it appears to the driver as if the rotation speed immediately became 0 with the initiation of idling stop.

[0020] Because the crankshaft continues to rotate due to inertia even after fuel injection and ignition are stopped, the first rotation speed N1 based on the crank angle sensor 7 gradually decreases after time t1. Because the first rotation speed N1 is a value obtained each time a crank angle sensor signal is input, its change is step-like, as shown in the figure. The second rotation speed N2 obtained by filtering the first rotation speed N1 also gradually decreases with a delay from the stop of fuel injection and ignition at time t1. For example, at time t2 when the rotation speed indication on the tachometer 21 becomes zero based on the pseudo rotation speed N3, the first rotation speed N1 and the second rotation speed N2 have not yet reached zero.

[0021] 2, at time t3 when the first rotation speed N1 and the second rotation speed N2 have not yet reached 0, the idling stop activation flag is turned OFF, for example, when the driver releases the brake pedal. However, the rotation speed display on the tachometer 21 continues to display the pseudo rotation speed N3, that is, continues to display 0.

[0022] When the idling stop operation flag is turned OFF, the restart process of the internal combustion engine 1 is started, and at time t4, an operation determination of the internal combustion engine 1 is made. That is, the engine state determination flag is turned OFF. In response to this operation determination, the rotation speed display on the tachometer 21 is switched from the pseudo rotation speed N3 to, for example, the second rotation speed N2 (in the case of idling). That is, if the vehicle remains in the idling state, the display of the second rotation speed N2 is resumed. Thereafter, the second rotation speed N2 is displayed while idling, and the first rotation speed N1 is displayed once the vehicle starts traveling.

[0023] As a comparative example, if the rotation speed display on the tachometer 21 is switched from the pseudo rotation speed N3 to the second rotation speed N2 (or the first rotation speed N1) at time t3 in response to the idling stop activation flag being turned OFF, the value of the tachometer 21 will rise suddenly and temporarily from 0 to the value N2(t3) of the second rotation speed N2 at that time, as can be easily understood from Fig. 2. In other words, to the driver, it will appear as if the rotation speed display has risen suddenly while the internal combustion engine 1 is still stationary, which will cause the driver to feel uncomfortable.

[0024] As in the above embodiment, if the display is switched from the pseudo rotation speed N3 to the second rotation speed N2 at time t4 when the operation determination of the internal combustion engine 1 is completed, the driver will not feel any discomfort because the rotation speed will increase when the internal combustion engine 1 actually starts to operate.

[0025] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, the present invention can be applied to an internal combustion engine that is a so-called diesel engine. Furthermore, the transmission is not limited to a stepped automatic transmission, and may be a combination of a continuously variable transmission or a manual transmission with an internal combustion engine. [Explanation of symbols]

[0026] 1...Internal combustion engine 7...Crank angle sensor 11...Controller 21...Tachometer

Claims

1. A method for displaying the rotation speed of an internal combustion engine for a vehicle equipped with an idling stop function on a tachometer of the vehicle, comprising: determining a first rotation speed each time a pulse signal is input based on a time interval between pulse signals of the crank angle sensor; The first rotation speed value outputted in a discrete manner is filtered for smoothing to obtain a second rotation speed; displaying the second rotation speed on the tachometer while the vehicle is idling while stopped, and generating a pseudo rotation speed signal that is pseudo to 0 when the vehicle is idling stopped, and displaying the pseudo rotation speed signal on the tachometer; After restarting the internal combustion engine from an idling stop state, the display of the pseudo rotation speed signal is continued until it is determined that the internal combustion engine is in operation. A method for displaying the rotation speed of an internal combustion engine.

2. The pseudo rotation speed signal is generated so as to decrease from the actual rotation speed during idling stop to 0 at a predetermined rate of change.

2. The method for displaying the rotational speed of an internal combustion engine according to claim 1.

3. After determining that the internal combustion engine is in operation, if the vehicle is in an idling state while stopped, the display of the second rotation speed is resumed.

2. The method for displaying the rotational speed of an internal combustion engine according to claim 1.

4. while the vehicle is running, displaying the first rotation speed on the tachometer; 2. The method for displaying the rotational speed of an internal combustion engine according to claim 1.

5. an internal combustion engine for a vehicle equipped with an idling stop function; a crank angle sensor that outputs a pulse signal for each unit crank angle of the internal combustion engine; a tachometer provided in the vehicle; a controller for displaying the rotation speed of the internal combustion engine on the tachometer; In an internal combustion engine rotation speed display device comprising: The above controller is determining a first rotation speed every time a pulse signal is input based on a time interval between pulse signals of the crank angle sensor; The first rotation speed value outputted in a discrete manner is filtered for smoothing to obtain a second rotation speed; displaying the second rotation speed on the tachometer while the vehicle is idling while stopped, and generating a pseudo rotation speed signal that is pseudo to 0 when the vehicle is idling stopped, and displaying the pseudo rotation speed signal on the tachometer; After restarting the internal combustion engine from an idling stop state, the display of the pseudo rotation speed signal is continued until it is determined that the internal combustion engine is in operation. RPM display device for internal combustion engines.

Images