JP2000291478A - Control device for automatic stop of vehicle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a special outside air temperature sensor and reduce the number of part items and cost by detecting cooling water temperature and intake temperature of an engine, obtaining a temperature difference between the detected cooling water temperature and intake temperature, and estimating outside air temperature according to the intake temperature, when the temperature difference is a prescribed value or less. SOLUTION: In a vehicle having a system, where when a designated stop condition is established, an engine is stopped automatically and when a designated re-start condition is established, the engine is restarted as one of stop conditions for the engine, the condition 'the outside air temperature is at a prescribed value or higher' is provided. The outside air temperature is estimated to determine whether this stop condition related to the outside air temperature is satisfied. In estimating the outside air temperature, when the engine is at cold start, the engine water temperature and the intake temperature are substantially equal values, so that it agrees with the outside air temperature. Therefore, the temperature difference between the cooling water temperature of the engine and the intake temperature of the engine is detected, and when the temperature difference is a prescribed value or smaller, the outside air temperature is estimated according to the intake temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outside air temperature estimating apparatus for a vehicle having no sensor for detecting outside air temperature.

[0002]

2. Description of the Related Art In recent years, the engine is automatically stopped when a predetermined stop condition is satisfied when the vehicle is stopped such as when waiting for a traffic light or during a traffic jam, and the engine is restarted when a predetermined restart condition is satisfied. The technology has been proposed and is already in practical use. With such a technology that automatically stops the engine, especially when the outside temperature is extremely low or when the engine is automatically stopped at extremely low temperatures in winter or other seasons, it becomes difficult to heat with the residual heat of the engine alone, and There was a problem that the comfort of the car was impaired.

Further, if the engine is stopped for a long time while the blower fan of the heating device is operated, the battery mounted on the vehicle is over-discharged, causing a so-called dead battery, which makes restarting difficult.

Therefore, taking this into consideration, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 8-140442 proposes a technique for preventing the automatic stop control of the engine from being performed when the outside air temperature is lower than a predetermined temperature.

[0005]

However, in order to detect the outside air temperature, a dedicated outside air temperature sensor is generally indispensable, and the number of parts increases and the cost increases accordingly.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and it is effective to use a sensor other than an outside air temperature sensor which is normally provided in a vehicle without installing an outside air temperature sensor exclusively. Accordingly, an object of the present invention is to provide a device for estimating an outside air temperature of a vehicle which can omit a special installation of an outside air temperature sensor by estimating the outside air temperature, and can reduce the number of components and thereby the cost.

[0007]

According to a first aspect of the present invention, there is provided an apparatus for estimating an outside air temperature in a vehicle having no sensor for detecting an outside air temperature, comprising: means for detecting a cooling water temperature of an engine; Means for detecting, and means for detecting a temperature difference between the cooling water temperature of the engine and the intake air temperature of the engine, and when the temperature difference is equal to or less than a predetermined value,
The above problem has been solved by estimating the outside air temperature based on the intake air temperature.

In general, the engine itself naturally cools down (same temperature as the outside air temperature) when the engine is stopped and sufficient time has passed. At this time, the engine water temperature W and the intake air temperature K usually show almost the same values as the outside air temperature. Starting the engine from this state (cold start)
It can be predicted to occur at least once a day. At this time, the temperature difference between the cooling water temperature of the engine and the intake air temperature of the engine is detected, and when the temperature difference is equal to or smaller than a predetermined value, that is, immediately after the cold start described above. When possible, the outside air temperature is estimated based on the intake air temperature.

In order to detect the temperature of the engine cooling water, an engine cooling water temperature sensor which is already installed in a commercially available vehicle may be used. Similarly, an intake air temperature sensor of a permanently installed engine may be used.

In this manner, the outside air temperature can be estimated by effectively utilizing the intake air temperature sensor and the engine cooling water temperature sensor which are generally provided permanently in the vehicle. There is no need to provide a dedicated device. For this reason, it is possible to reduce the number of parts and thereby the cost of parts. Further, it is useful in that the check can be always performed (when the conditions are satisfied) at the first engine start of the day.

According to a second aspect of the present invention, there is provided an external air temperature estimating apparatus for a vehicle having no sensor for detecting an external air temperature, comprising: means for detecting an intake air temperature of an engine; and means for detecting a vehicle speed. The above problem is also solved by estimating the outside air temperature based on the intake air temperature of the engine when the vehicle travels at a predetermined vehicle speed or more for a predetermined time or more.

[0012] It should be noted that, when estimating the outside air temperature based on the intake air temperature of the engine, it is performed when "the vehicle runs at a predetermined vehicle speed or more and for a predetermined time or more" in an embodiment described later. As will be described in detail, when the inventor drives the vehicle at a certain vehicle speed or more and for a predetermined time or more, the intake air temperature of the engine converges to a value having a certain difference from the outside air temperature (stabilizes. This is because it was found through experiments that there were characteristics.

[0013] By doing so, similar to the first aspect,
It is not necessary to provide an outside air temperature sensor, so that the number of parts and the cost of parts due to this can be reduced. In addition, even if the environment changes during driving, it can be followed.

According to a third aspect of the present invention, in the second aspect, a means for detecting an average vehicle speed when the vehicle travels at a predetermined vehicle speed or more for a predetermined time or more, and an intake air temperature of the engine. The above-mentioned problem is similarly solved by estimating the outside air temperature based on the vehicle speed and the average vehicle speed.

The present invention embodies the invention of claim 2 on a more practical level.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In this embodiment, an example of a vehicle equipped with a system for automatically stopping an engine when a predetermined stop condition is satisfied and restarting the automatically stopped engine when a predetermined restart condition is satisfied is described as an example. It will be described as. The present invention is not particularly limited to a vehicle that automatically stops and restarts the engine.

In this embodiment, a vehicle equipped with an automatic transmission will be described. However, as described above, the present invention is not particularly limited thereto, and a vehicle equipped with a manual transmission (MT) or a continuously variable transmission (CVT) is also applicable. The invention is applicable.

First, the drive system configuration to which the present embodiment is applied and the input / output relationship of signals when performing engine control and automatic engine stop control will be described with reference to FIG.

In FIG. 2, reference numeral 1 denotes an engine mounted on a vehicle, and 2 denotes an automatic transmission. In the engine 1, a motor generator 3 functioning as a motor and a generator for restarting the engine 1 is connected to a crankshaft 1a of the engine 1 via a clutch 26, a chain 27, and a reduction mechanism R. I have. Note that the engine starter may be provided separately from the motor generator 3, and the starter and the motor generator 3 may be used together when starting the engine, or the starter may be used exclusively at extremely low temperatures.

The reduction mechanism R is of a planetary gear type and has a sun gear 3
3, including a carrier 34, a ring gear 35, and a brake 3
1. It is incorporated between the motor generator 3 and the clutch 28 via the one-way clutch 32.

The oil pump 19 for the automatic transmission 2 is directly connected to the crankshaft 1 a of the engine 1 via clutches 26 and 28. The automatic transmission 2 is provided with a known forward clutch C1 that is engaged during forward traveling.

Reference numeral 4 denotes an inverter electrically connected to the motor generator 3. The inverter 4 varies the supply of electric energy from the battery 5 as a power source to the motor generator 3 by switching, thereby varying the rotation speed of the motor generator 3. Further, switching is performed such that electric energy is charged from motor generator 3 to battery 5.

Reference numeral 7 denotes a controller (hereinafter referred to as an eco-run ECU) for controlling the connection and disconnection of the clutches 26 and 28 and the switching control of the inverter 4 and the battery 5.

The controller 7 is linked to an engine ECU (electronic control unit) 80 for controlling an engine, an automatic transmission, and the like.

Engine ECU 80 and Eco-Run ECU 7
The input signals from the various sensor groups 90 are input and output.

The various sensor groups include, for example, an engine speed sensor 91 for detecting the engine speed NE, an engine coolant temperature sensor 92 for detecting the engine coolant temperature W,
Turbine rotation speed sensor 93 for torque converter, accelerator opening sensor 94 for detecting accelerator opening, engine intake temperature detecting sensor 95 for detecting engine intake temperature, shift position sensor 9 for detecting shift position
6, a sensor 97 for detecting the state of the ignition switch IG, a vehicle speed sensor 98 for detecting the vehicle speed, a switch sensor 99 for an automatic stop running mode (eco-run mode), and the like.

The signals from these sensors are transmitted to the eco-run ECU.
7, or input to the engine ECU 80. As described above, the eco-run ECU 7 and the engine ECU 80 can communicate these sensor input signals with each other.

As will be described later, the eco-run ECU includes:
Engine cooling water temperature sensor 92, engine intake air temperature sensor 9
5. There is a function of estimating the outside air temperature based on the vehicle speed sensor 99 and the like and a function of updating the estimated outside air temperature to a memory (outside air temperature memory).

In this embodiment, no outside air temperature sensor for detecting the outside air temperature is provided.

Further, in the present embodiment, the control for automatically stopping the engine when a predetermined engine stop condition is satisfied and the control for restarting the engine when the predetermined restart condition is satisfied according to the above configuration. Done.

The conditions for stopping the engine 1 include, for example, "vehicle speed is zero", "accelerator off", "brake on", "the shift position is a driven position", and "the outside air temperature is equal to or higher than a predetermined value". The restart condition is, for example, when any one of the engine stop conditions is not satisfied. Note that the above conditions are merely examples, and the present invention is not limited to these conditions.

The introduction of "outside air temperature is equal to or higher than a predetermined value" as one of the engine stop conditions is particularly attributable to a decrease in the battery charge acceptance performance, a deterioration in the efficient discharge characteristics of the battery, and This is because it is considered that the engine startability is reduced due to an increase in friction and the like. That is, when the outside air temperature is lower than a predetermined value, the automatic stop control of the engine is stopped to prevent the battery from running out, and further to prevent the life from being shortened by the deep discharge.

The estimation of the outside air temperature according to the present invention is applied to determine whether or not the stop condition regarding the outside air temperature is satisfied.

First, a first embodiment of the estimation of the outside air temperature according to the present invention will be described.

When a sufficient time has elapsed since the engine was stopped, the engine itself naturally cools down (has a temperature similar to the outside air temperature). The act of starting the engine from this state (cold start) can generally be expected to occur at least once a day. Only at the time of the cold start, the engine water temperature W and the intake air temperature K become substantially the same value, which can be said to be equal to the outside air temperature.

Therefore, in the present embodiment, the temperature difference between the engine cooling water temperature W and the engine intake temperature K is detected, and when the temperature difference is equal to or less than a predetermined value, the outside air temperature G is determined based on the intake temperature K. Estimate (assuming that intake air temperature = outside air temperature). Further, since the outside air temperature at this time substantially coincides with the intake air temperature and the engine water temperature, it can be used to reset (set a reference point) the estimated value of the outside air temperature set in advance. Then, the memory value of the outside temperature is updated.

In this manner, the outside air temperature can be estimated by effectively utilizing the intake air temperature sensor 125 and the engine cooling water temperature sensor 123 which are generally permanently installed in the vehicle. For this reason, it is possible to reduce the number of parts and thereby the cost of parts.

This method is also advantageous in that the outside air temperature G can be measured at least once a day at the time of departure.

Next, a second embodiment will be described.

In the second embodiment, as in the first embodiment, the vehicle is not provided with an outside air temperature sensor. In the second embodiment, based on respective detection values output from a vehicle speed sensor 99 that is permanently installed in a vehicle that is already on the market and an engine intake air temperature sensor 125 that is also used in the first embodiment. To estimate the outside temperature. This method is useful mainly for detecting (updating) the outside air temperature when the environment changes during running.

Here, the estimation of the outside air temperature will be described in detail based on the results of the experimental data shown in FIGS.

3 to 7, the horizontal axis represents time t, and the vertical axis represents vehicle speed v and temperature Tem, and represents intake air temperature K, engine cooling water temperature W, vehicle speed V, and outside air temperature G, respectively.

In the present embodiment, since the estimation of the outside air temperature is the main, the values of the outside air temperature are also shown in FIGS. 3 to 7 in order to explain the validity of the estimation method.

First, FIGS. 3 to 5 will be described.

FIGS. 3 to 5 have different vehicle speeds in the respective drawings, but in each of the drawings, the vehicle runs at a constant vehicle speed (constant speed). Here, the fixed speeds are respectively set to V1, V2, and V3 (V1 <V2 <V3). Note that the average vehicle speeds are V1 and V
2, V3. In FIGS. 3 to 5, the graphs are displaced up and down because real detection values are taken in real time.

The graph lines shown in FIGS.
a, Vb, Vc are vehicle speeds, Wa, Wb, Wc are engine cooling water temperatures, Ka, Kb, Kc are intake air temperatures, Ga, Gb, Gc.
Indicates the outside temperature.

FIGS. 3 to 5 show a state in which the vehicle speed is generated slightly before time t1, and as is clear from the graph of the engine cooling water temperature W, the engine itself has already been sufficiently warmed up. Data.

According to the data shown in FIGS. 3 and 4, the intake air temperatures Ka and Kb temporarily rise near the time t1 when the vehicle speed occurs. This is because the air intake temperature per unit time is small and the intake air temperature is likely to rise (due to the heat of the engine).

As described above, since the vehicle is traveling at a constant speed in FIGS. 3 to 5, the engine cooling water temperatures Wa, Wb,
Wc does not rise or fall sharply, but eventually shows a tendency to settle down at a substantially constant value.

The transition of the intake air temperatures Ka, Kb, and Kc is such that, even when the average vehicle speeds V1, V2, and V3 are different, if the vehicle continuously runs at a certain vehicle speed that is equal to or higher than a certain vehicle speed, all intake air temperatures approach the outside air temperature. Tem with a certain difference from outside temperature
θ1, Temθ2, and Temθ3 (convergence temperature of the intake air temperature) and calm down. The constant differences between the intake air temperature K and the outside air temperature G at this time are denoted by H1, H2, and H3, respectively.

Differences H1 and H between the intake air temperature K and the outside air temperature G
2, H3 depends on the constant vehicle speed V and the outside air temperature G as is clear from FIGS. That is, in other words, for each outside temperature, the vehicle speed V,
If the difference H between the outside air temperature G and the intake air temperature K is mapped, for example, as shown in FIG. 8 (described later), the intake air temperature K and the vehicle speed V
Means that the outside air temperature G is required.

Next, FIGS. 6 and 7 show that the vehicle speed is not constant.
When the temperature changes within a certain range, the outside temperature G, the vehicle speed v,
The relationship between the intake air temperature K and the engine cooling water temperature W will be described.

FIG. 6 shows the vehicle speed in the range of v8 to v10, and FIG. 7 shows the vehicle speed in the range of v8 to v10 (intentionally), with the average vehicle speed being V4 and V5, respectively. It is.

6 and 7, the horizontal axis represents time t, the vertical axis represents vehicle speed v, and the temperature Tem, Vd and Ve represent vehicle speed, Wd and We represent engine coolant temperature, and the graph line in FIG.
Kd and Ke indicate the intake air temperature, and Gd and Ge indicate the outside air temperature, respectively.

In both FIGS. 6 and 7, since the vehicle speed changes within a certain range, the intake air temperature Kd and Ke are affected by the change.
Is also pulsating and changing. It is considered that this is because the intake amount of air per unit time changes due to a change in vehicle speed (acceleration change). However, the intake air temperature K
3 and FIG. 5 (when the vehicle is traveling at a constant speed), while the vehicle is traveling at a predetermined vehicle speed or higher for a predetermined period of time, as shown in FIGS. It can be seen that the air temperature approaches the external air temperatures Gd and Ge, and finally, the air temperature becomes constant Temθ4 and Temθ5 (convergent temperature of the intake air temperature) having certain differences H4 and H5, indicating that the air temperature is calm down.

Next, a third embodiment will be described.

FIG. 8 is a graph (map) for estimating the outside air temperature with the horizontal axis representing the vehicle speed and the vertical axis representing the temperature.

In FIG. 8, points A1, A2, and A3 are points representing the vehicle speed and the convergence temperature of the intake air temperature when traveling at the constant vehicle speed described with reference to FIGS. Points B1 and B2 represent the average vehicle speed and the convergence temperature of the intake air temperature when the vehicle speed fluctuates within a certain range described with reference to FIGS. 6 and 7, respectively.

From these comparisons, the vehicle speed is changed within a certain range on the intake air temperature line created from the data obtained as a result of running at a constant speed at the vehicle speeds V1, V2, V3 described with reference to FIGS. It can be confirmed that the measurement results of the average vehicle speeds V5 and V4 in the case where the vehicle is running are exactly on. That is, from this, if the vehicle speed is equal to or higher than the predetermined value, even if the vehicle is not running at a constant vehicle speed, the reasoning of FIGS. 3 to 5 can be directly extended and applied by taking the average vehicle speed. I understand.

Accordingly, the average vehicle speed (V1 to V5) when the vehicle speed V is equal to or greater than the predetermined value and the vehicle has traveled for a predetermined time or more.
If the intake air temperature K is known, it can be said that the outside air temperature G can be estimated (from a map as shown in FIG. 8) based on the intake air temperature K (even if the vehicle speed is not always constant).

In this way, the outside air temperature can be estimated by effectively using the intake air temperature sensor 125 permanently installed in the vehicle, and it is not necessary to install a special outside air temperature sensor. The number of parts can be reduced, and the manufacturing cost can be reduced accordingly.

By being able to estimate the outside temperature in this way, it can be considered as one of the conditions for the automatic stop control of the engine, as in the above-described embodiment. If it is considered that the blower heating performance is degraded by looking at it, it can be used for more sophisticated automatic control of the air conditioner by judging that it is a situation that will make the driver feel cold. it can.

Next, a control flow based on the first to third embodiments will be described.

In FIG. 1, in step 200, the engine starts and this routine starts to run. In step 210, a temperature difference between the engine cooling water temperature W and the intake air temperature K is detected, and it is determined whether the temperature difference is equal to or less than a predetermined value a. If it is determined that the temperature difference is equal to or smaller than the predetermined value a, the process proceeds to step 220, and the intake air temperature K is regarded as the outside air temperature G, and the memory value of the outside air temperature is updated. At step 210,
If it is determined that the temperature difference between the engine water temperature W and the intake air temperature K is larger than the predetermined value a, the process proceeds to step 230, and the previous external temperature memory value is used.

The temperature difference between the engine cooling water temperature W and the intake air temperature K can be detected as long as the temperature difference is within a predetermined value a regardless of which temperature is higher. (Intake temperature).

In step 240, it is determined whether or not the vehicle is running at a predetermined vehicle speed or more and for a predetermined time or more. If this condition is not satisfied, the process loops in this step. If the condition is satisfied, the process proceeds to step 250, where the outside air temperature is estimated from a map of the intake air temperature and the average vehicle speed during the predetermined time. Then, the external temperature memory value is determined.

In step 260, the ignition IG
Is determined to be off. When the ignition IG is turned off, the external temperature determined at that time is stored, and this routine ends. When the ignition IG remains on, the process returns to step 240, and the process loops in the mode for estimating the outside air temperature.

[0069]

According to the present invention, it is possible to eliminate the need to specially provide an outside air temperature sensor, thereby realizing a reduction in the number of parts and a reduction in the cost of parts.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of control contents of an embodiment for estimating an outside temperature of a vehicle according to the present invention.

FIG. 2 is a diagram showing a system configuration of an engine drive device of a vehicle to which the present invention is applied, and a relationship between input and output signals to an engine ECU and an eco-run ECU.

FIG. 3 is a diagram showing the intake air temperature, the engine cooling water temperature, and the outside air temperature at a fixed vehicle speed V1, the time on the horizontal axis, and the vehicle speed and temperature on the vertical axis.

FIG. 4 is a diagram showing the intake air temperature, the engine cooling water temperature, and the outside air temperature at a fixed vehicle speed V2 along time on the horizontal axis and vehicle speed and temperature on the vertical axis.

FIG. 5 is a diagram showing the intake air temperature, the engine cooling water temperature, and the outside air temperature at a fixed vehicle speed V3 along the time on the horizontal axis and the vehicle speed and temperature on the vertical axis.

FIG. 6 is a diagram showing intake air temperature, engine cooling water temperature, and outside air temperature when the vehicle speed changes within a certain range (average vehicle speed V4), with time on the horizontal axis and vehicle speed and temperature on the vertical axis.

FIG. 7 is a diagram showing the intake air temperature, the engine cooling water temperature, and the outside air temperature when the vehicle speed changes within a certain range (average vehicle speed V5), with time on the horizontal axis and vehicle speed and temperature on the vertical axis.

FIG. 8 is a graph (map) for estimating an outside air temperature in which a horizontal axis represents a vehicle speed and a vertical axis represents a temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Automatic transmission 3 ... Motor generator 4 ... Inverter 5 ... Battery 7 ... Eco-run ECU 19 ... Oil pump 40 ... Eco-run switch 80 ... Engine control ECU 85 ... Vehicle speed 123 ... Engine cooling water temperature sensor 125 ... Engine intake temperature sensor G: Outside air temperature W: Engine cooling water temperature K: Intake air temperature

Claims (3)

[Claims] An apparatus for estimating an outside air temperature in a vehicle having no sensor for detecting an outside air temperature, a means for detecting a cooling water temperature of an engine, a means for detecting an intake air temperature of an engine, a cooling water temperature of the engine and the engine Means for detecting a temperature difference between the intake air temperature and the intake air temperature, wherein when the temperature difference is equal to or less than a predetermined value, an external air temperature is estimated based on the intake air temperature. 2. An external air temperature estimating apparatus for a vehicle having no sensor for detecting an external air temperature, comprising: means for detecting an intake air temperature of an engine; and means for detecting a vehicle speed. And an outside air temperature estimating device for estimating the outside air temperature based on the intake air temperature of the engine when the vehicle travels for a predetermined time or more. 3. The vehicle according to claim 2, further comprising: means for detecting an average vehicle speed when the vehicle travels at a predetermined vehicle speed or more for a predetermined time or more, and based on the engine intake temperature and the average vehicle speed. An outside air temperature estimating device for a vehicle, wherein the outside air temperature is estimated.