Vehicle controller

Abstract

To provide a vehicle controller capable of determining an appropriate target idle speed according to both a water temperature of an engine and an oil temperature of a transmission.SOLUTION: A control unit has a correction amount table in which a correction amount is determined according to a cooling water temperature of an engine and an oil temperature of a transmission. The control unit always detects the water temperature and the oil temperature, and determines a target idle speed by adding the correction amount based on the correction amount table to a standard target idle speed determined based on the water temperature. The correction amount table determines the correction amount according to a combination of the water temperature and the oil temperature. Alternatively, the correction amount table determines the correction amount based on a temperature difference between the water temperature and the oil temperature.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 describes an idle speed control device that detects the temperature of the oil in the transmission and corrects the target idle speed of the engine to a higher speed if the oil temperature is below a predetermined temperature. This idle speed control device corrects the target idle speed to a higher speed by a fixed value only if the transmission oil temperature is below the predetermined temperature after the engine water temperature has risen (see Figures 3 and 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 03-115755 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 1 cannot correct the target idle speed in consideration of the transmission oil temperature before the engine water temperature rises. Furthermore, the correction amount is a constant value regardless of the transmission oil temperature. Therefore, the technology described in Patent Document 1 has the problem of being unable to determine an appropriate target idle speed in accordance with both the engine water temperature and the transmission oil temperature.

[0005] The present invention has been made in light of the above-mentioned circumstances, and aims to provide a vehicle control device that can determine an appropriate target idle speed in accordance with both the engine water temperature and the transmission oil temperature. [Means for solving the problem]

[0006] The present invention provides a vehicle control device that is mounted on a vehicle having an engine and a transmission that changes the speed of rotation transmitted from the engine, and that includes a control unit that determines a target idle speed of the engine.The control unit has a correction amount table in which a correction amount is determined according to the water temperature of the engine's cooling water and the oil temperature of the transmission, and determines the target idle speed by constantly detecting the water temperature and the oil temperature and adding the correction amount based on the correction amount table to a standard target idle speed that is determined based on the water temperature. [Effects of the Invention]

[0007] As described above, according to the present invention, it is possible to provide a vehicle control device that can determine an appropriate target idle speed in accordance with both the engine water temperature and the transmission oil temperature. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a correction amount table to which the vehicle control device according to the embodiment of the present invention refers. [Figure 3] FIG. 3 is a diagram showing another example of a correction amount table to be referred to by the vehicle control device according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the correlation of friction with oil temperature of a transmission in a vehicle control device according to an embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing the correlation of friction with respect to the rotation speed and oil temperature of the transmission in the vehicle control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to one embodiment of the present invention is mounted on a vehicle having an engine and a transmission that changes the speed of rotation transmitted from the engine, and includes a control unit that determines a target idle speed of the engine, wherein the control unit has a correction amount table in which correction amounts are determined according to the temperature of engine coolant and the temperature of transmission oil, and determines the target idle speed by constantly detecting the water temperature and the oil temperature and adding the correction amount based on the correction amount table to a reference target idle speed determined based on the water temperature. This allows the vehicle control device according to one embodiment of the present invention to determine an appropriate target idle speed according to both the engine water temperature and the transmission oil temperature. [Example]

[0010] A vehicle control device according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 10 includes an engine 20, a transmission 30, and a control unit 50 that controls the vehicle 10 in an overall manner.

[0012] The engine 20 has multiple cylinders. In this embodiment, the engine 20 is configured to perform a series of four strokes for each cylinder: an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. Cooling water flows through the engine 20.

[0013] The transmission 30 changes the speed of the rotation transmitted from the engine 20 and transmits the changed rotation to a drive shaft and drive wheels (not shown). The transmission 30 is an automatic transmission that uses a planetary gear mechanism to change gears in stages. Oil circulates inside the transmission 30. The transmission 30 is equipped with a torque converter 38, and changes the speed of the rotation transmitted from the engine 20 via this torque converter 38.

[0014] The vehicle 10 is provided with a vehicle speed sensor 15, an accelerator opening sensor 16, and a shift range operation unit 17. The vehicle speed sensor 15 detects the vehicle speed and transmits a detection signal to the control unit 50. The accelerator opening sensor 16 detects the amount of depression of an accelerator pedal (not shown) and transmits a detection signal as an accelerator opening to the control unit 50. The shift range operation unit 17 allows the driver to switch the shift range of the transmission 30.

[0015] The control unit 50 has an engine controller (referred to as ECM in the drawing) 50A that controls the engine 20, and a transmission controller (referred to as TCM in the drawing) 50B that controls the transmission 30.

[0016] The engine controller 50A and the transmission controller 50B are each composed of a computer unit (ECU: Electronic Control Unit) equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0017] The ROM of the computer unit stores various constants, maps, etc., as well as programs for making the computer unit function, and the CPU executes the programs stored in the ROM using the RAM as a working area.

[0018] The engine 20 is provided with an engine speed sensor 27 and a throttle opening sensor 28. The engine speed sensor 27 detects the engine speed generated by the engine 20 based on the rotational position of a crankshaft (not shown) and transmits a detection signal to an engine controller 50A of the control unit 50. The throttle opening sensor 28 detects the opening of a throttle valve (not shown) and transmits a detection signal to the engine controller 50A of the control unit 50.

[0019] A water temperature sensor 20A is provided in the engine 20. The water temperature sensor 20A detects the temperature of the cooling water of the engine 20 and transmits a detection signal to an engine controller 50A of the control unit 50.

[0020] An oil temperature sensor 30A is provided in the transmission 30. The oil temperature sensor 30A detects the temperature of the oil in the transmission 30 and sends a detection signal to the transmission controller 50B of the control unit 50. The oil in the transmission 30, whose temperature is detected by the oil temperature sensor 30A, is not limited to oil that lubricates the internal gear change mechanism of the transmission 30, but may also be oil in the torque converter 38 (so-called AT fluid).

[0021] In the control unit 50, the oil temperature detected by the oil temperature sensor 30A is transmitted from the transmission controller 50B to the engine controller 50A via CAN communication. In this embodiment, the functions are divided between the engine controller 50A and the transmission controller 50B, but these controllers may be integrated into one. In the following description, it is assumed that the control unit 50 is the main controller of the engine 20 and the transmission 30.

[0022] The control unit 50 determines a target idle rotation speed of the engine 20. The target idle rotation speed is a target value of the idle rotation speed.

[0023] After a cold start of the engine 20, the control unit 50 performs idle-up to correct the target idle speed to the increasing side based on the temperature of the coolant of the engine 20, in order to prevent the engine from stalling due to high viscosity and rotational resistance of the engine oil at low temperature. The control unit 50 performs control so that the lower the water temperature of the engine 20, the greater the amount of idle-up correction.

[0024] The load of the transmission 30 is transmitted to the engine 20. The oil in the transmission 30 has a characteristic of becoming more viscous as the oil temperature is low. Therefore, the lower the oil temperature of the transmission 30, the greater the friction inside the transmission 30 and the greater the load transmitted from the transmission 30 to the engine 20, increasing the possibility of engine stall. For example, if the vehicle 10 coasts with the accelerator pedal released immediately after a cold start in a cold region, or if the vehicle is stopped with the shift position of the transmission 30 in D range (forward driving range), a large load is transmitted from the transmission 30 to the engine 20 during idle operation.

[0025] Therefore, in this embodiment, the control unit 50 constantly detects not only the water temperature of the engine 20 but also the oil temperature of the transmission 30, and determines the target idle speed taking both the water temperature and the oil temperature into consideration. In other words, the control unit 50 does not switch whether to increase the target idle speed based on a comparison with a predetermined water temperature threshold or oil temperature threshold that indicates completion of warm-up of at least one of the engine 20 and the transmission 30, but instead constantly monitors the water temperature and oil temperature to set the target idle speed for all temperature conditions.

[0026] The control unit 50 has a correction amount table in which correction amounts are determined according to the water temperature of the engine 20 coolant and the oil temperature of the transmission 30. The control unit 50 constantly detects the water temperature and oil temperature, and determines the target idle speed by adding a correction amount based on the correction amount table to a reference target idle speed determined based on the water temperature. In other words, the correction amount is an increase in the rotation speed relative to the reference target idle speed determined based on the water temperature, taking into account the oil temperature.

[0027] As shown in FIG. 2, in the correction amount table, a correction amount is determined according to a combination of water temperature (referred to as EG water temperature in the figure) and oil temperature (referred to as TM oil temperature in the figure). In FIG. 2, a correction amount is set for each combination of a plurality of oil temperatures relative to a plurality of water temperatures. This correction amount table sets an appropriate correction amount experimentally determined using an actual vehicle for each combination of the temperature of the coolant in the engine 20 and the temperature of the oil in the transmission 30. Specifically, the lower the coolant temperature and the lower the oil temperature, the larger the correction amount is set so that the number of revolutions (rotational speed) of the engine 20 is increased. Then, the higher the coolant temperature and the higher the oil temperature, the smaller the correction amount (increase).

[0028] When it is desired to utilize a correction for the coolant temperature of the engine 20 that is commonly used in existing vehicles, the correction amount may be determined in a correction amount table according to the temperature difference between the water temperature (referred to as EG water temperature in the figure) and the oil temperature (referred to as TM oil temperature in the figure), as shown in FIG. 3. In FIG. 3, the correction amount is set according to a plurality of temperature differences. This correction amount table also sets an appropriate correction amount experimentally determined using an actual vehicle for each temperature difference between the coolant temperature of the engine 20 and the oil temperature of the transmission 30. Specifically, the correction amount is set to be larger as the temperature difference increases, thereby increasing the rotation speed (rotational speed) of the engine 20. Note that when the coolant temperature is low and the oil temperature is high, no correction is performed even though there is a temperature difference.

[0029] 4, the lower the oil temperature of the transmission 30 (referred to as TM oil temperature in the figure), the greater the friction in the transmission 30, and the higher the oil temperature, the smaller the friction.

[0030] Preferably, the control unit 50 uses the oil temperature at point A, where the oil temperature in transmission 30 is high and friction is low, as a reference, and starts correcting the target idle speed (adding a correction amount to the reference target idle speed) when the oil temperature is below the temperature at point A, and ends the correction (setting the correction amount to 0) when the oil temperature rises to or above point A. Furthermore, when the oil temperature in transmission 30 is at point B, where the oil temperature is low and friction is high, it is preferable to determine the correction amount so as to ensure a friction difference C obtained by subtracting the friction at point A from the friction at point B. Note that the control unit 50 also preferably determines the reference target idle speed, which is based on the water temperature of engine 20 itself and does not take into account the oil temperature of transmission 30, based on the correlation between the water temperature of engine 20 and the friction of engine 20, similar to the correlation shown in FIG. 4.

[0031] As shown in Fig. 5, the friction of the transmission 30 changes depending on the rotation speed of the torque converter 38 of the transmission 30 (referred to as TM rotation speed in the figure). The higher the rotation speed of the torque converter 38 of the transmission 30, the greater the friction of the transmission 30. When calculating the friction of the transmission 30, the control unit 50 preferably determines the correction amount taking into account not only the oil temperature of the transmission 30 but also the rotation speed of the torque converter 38. In other words, it is preferable that the correction amount table is set with the correction amount taking into account the rotation speed of the torque converter 38.

[0032] Note that the control unit 50 may correct the target idle speed when idle stop of the engine 20 is not successful. This allows the correction of the target idle speed only when the engine 20 is operating in a low-temperature environment, excluding situations where the engine 20 is stopped while the vehicle speed is decelerating due to idle stop, thereby making it possible to suppress engine stall.

[0033] Furthermore, control unit 50 may correct the target idle speed when the shift position is in a position other than D range. As a result, when the driver sets the shift position to sport mode or L range because he or she wants to use engine braking, friction increases due to the gear ratio in transmission 30, and engine stall due to this increase in friction can be suppressed by correcting the target idle speed.

[0034] Furthermore, the control unit 50 may correct the target idle speed when the steering wheels are steered at a specific steering angle in the electric power steering. This makes it possible to suppress engine stalls caused by increased friction in the electric power steering by correcting the target idle speed.

[0035] Furthermore, the control unit 50 may correct the target idle speed when it is determined that the vehicle 1 is decelerating suddenly because the deceleration of the vehicle speed is large or the brake pedal is depressed heavily, or when it is determined that the vehicle 1 is decelerating suddenly because a G sensor provided for operating an airbag or the like is equal to or greater than a specific value. As a result, in addition to the control to increase the intake amount that is performed to prevent engine stall when the vehicle 1 is suddenly decelerating, the correction of the target idle speed according to this embodiment is also performed, so that engine stall can be effectively suppressed.

[0036] As described above, in this embodiment, control unit 50 has a correction amount table in which correction amounts are determined according to the water temperature of the coolant for engine 20 and the oil temperature for transmission 30. Control unit 50 constantly detects the water temperature and oil temperature, and determines the target idle speed by adding a correction amount based on the correction amount table to a reference target idle speed determined based on the water temperature.

[0037] This makes it possible to determine an appropriate target idle speed in accordance with both the load on engine 20, which is dependent on the water temperature of engine 20, and the load on transmission 30, which is dependent on the oil temperature of transmission 30. As a result, it is possible to determine an appropriate target idle speed in accordance with both the water temperature of engine 20 and the oil temperature of transmission 30. Furthermore, because it is possible to determine an appropriate target idle speed, it is possible to avoid setting an unnecessarily high target idle speed, thereby suppressing deterioration in fuel economy.

[0038] In this embodiment, the correction amount table defines the correction amount according to the combination of the water temperature and the oil temperature.

[0039] This makes it possible to determine an appropriate target idle speed in accordance with both the load on the engine 20, which is dependent on the water temperature of the engine 20, and the load on the transmission 30, which is dependent on the oil temperature of the transmission 30.

[0040] As a result, an appropriate target idle speed can be determined in accordance with both the water temperature of the engine 20 and the oil temperature of the transmission 30. Furthermore, because an appropriate target idle speed can be determined, it is possible to avoid setting an unnecessarily high target idle speed, thereby suppressing deterioration in fuel economy.

[0041] In this embodiment, the correction amount table defines the correction amount according to the temperature difference between the water temperature and the oil temperature.

[0042] This makes it possible to determine an appropriate target idle speed in accordance with both the load on the engine 20, which is dependent on the water temperature of the engine 20, and the load on the transmission 30, which is dependent on the oil temperature of the transmission 30.

[0043] As a result, an appropriate target idle speed can be determined in accordance with both the water temperature of the engine 20 and the oil temperature of the transmission 30. Furthermore, because an appropriate target idle speed can be determined, it is possible to avoid setting an unnecessarily high target idle speed, thereby suppressing deterioration in fuel economy.

[0044] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0045] 10 vehicles 20 Engine 30 Transmission 50 control section

Claims

1. The vehicle is equipped with an engine and a transmission that changes the speed of rotation transmitted from the engine, A vehicle control device including a control unit that determines a target idle speed of the engine, The control unit a correction amount table in which a correction amount is determined according to the temperature of the engine cooling water and the temperature of the transmission oil; a control device for a vehicle, characterized in that the target idle speed is determined by constantly detecting the water temperature and the oil temperature, and adding the correction amount based on the correction amount table to a reference target idle speed determined based on the water temperature.

2. 2. The vehicle control device according to claim 1, wherein the correction amount is determined in the correction amount table according to a combination of the water temperature and the oil temperature.

3. 2. The vehicle control device according to claim 1, wherein the correction amount is determined in the correction amount table according to a temperature difference between the water temperature and the oil temperature.

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