JP2005282453A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent vehicle stopping at an ascent road from reversing without giving a driver a sense of incongruity. <P>SOLUTION: An engine ECU executes a program including a step S130 estimating a stop position of a vehicle at the ascent road, a step S140 acquiring ascent road gradient at the vehicle stop position from a navigation system, a step S150 calculating idling up speed from the ascent road gradient, and a step S170 executing idling up process if engine speed of the vehicle drops to idling up start speed or less (YES in S160) when an accelerator is turned off during travel on the ascent road (YES in S110) and brake is applied (YES in S120). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device, and more particularly, to a device for controlling creep torque so that a vehicle can maintain a stop state on an uphill using the creep torque of an automatic transmission.

  An automatic transmission mounted on a vehicle is configured to include a transmission mechanism that is connected to an engine via a torque converter or the like and has a plurality of power transmission paths. For example, an automatic transmission is automatically set based on an accelerator opening and a vehicle speed. The power transmission path is automatically switched, that is, the gear ratio (travel speed stage) is automatically switched. Generally, a vehicle having an automatic transmission is provided with a shift lever operated by a driver, and a shift position (for example, a reverse travel position, a neutral position, a forward travel position) is set based on the shift lever operation. The automatic shift control is performed within the thus set shift position (usually in the forward travel position).

  In a vehicle having such an automatic transmission, in a state where the forward traveling position is set and the vehicle is stopped, the driving force from the idling engine is transmitted to the transmission via the torque converter, which is the wheel. Therefore, a so-called creep phenomenon occurs. The creep phenomenon has useful points such as maintaining the stop state of the vehicle on the uphill road and allowing the vehicle to start smoothly from the stop state.

  Japanese Laid-Open Patent Publication No. 61-99762 (Japanese Patent Publication No. 1-39507: Patent Document 1) uses the creep torque of an automatic transmission to control the creep torque so that the vehicle can be held on an uphill road. A creep torque control device for an automatic transmission is disclosed. The creep torque control device for an automatic transmission includes a road surface gradient sensor that detects a road surface gradient and a creep torque that balances a reverse torque according to the road surface gradient in a vehicle that is driven by power from an engine via the automatic transmission. Engine speed setting means for setting the target engine speed for generating engine, engine speed detection means for detecting the actual engine speed, and idle speed for controlling the engine so that the actual engine speed becomes the target engine speed Control means.

According to this automatic transmission creep torque control device, the idle speed control means idle controls the engine so that the engine speed detected by the engine speed detection means becomes the target speed set by the engine speed setting means. . For this reason, the creep torque of the automatic transmission is balanced with the reverse torque according to the road surface gradient, and the vehicle can be automatically held on the steep ascending slope without the accelerator operation.
Japanese Patent Application Laid-Open No. 61-99762 (Japanese Patent Publication No. 1-39507)

  However, in Patent Document 1 described above, after it is determined that the vehicle is not desired to start, the engine speed increases so that the necessary creep torque can be generated based on the road surface gradient. . In this case, the engine speed increases after the vehicle stops on the uphill road, which gives the driver a sense of discomfort.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle control device that can prevent the vehicle from retreating on an uphill road without causing the driver to feel uncomfortable. It is to be.

  According to a first aspect of the present invention, there is provided a vehicle control apparatus that controls a vehicle that travels driving force from an engine via an automatic transmission. The control device predicts that the vehicle stops on the uphill road, and if the vehicle is predicted to stop on the uphill road, the control device sets the engine speed before stopping the vehicle on the uphill road. Control means for controlling the engine so as to be raised according to the road surface gradient of the uphill road.

  According to the first invention, when it is predicted that the vehicle stops on the uphill road, the engine speed is increased according to the road surface gradient of the uphill road before the stop. Thus, the engine speed can be increased so that a creep force corresponding to the road gradient of the uphill road can be generated before the vehicle stops. For this reason, after the vehicle stops on the uphill road, the vehicle does not increase the idle rotation speed so that the creep force according to the road surface gradient on the uphill road can be generated, and the driver does not feel uncomfortable. The engine speed can be increased before stopping. As a result, it is possible to provide a vehicle control device that can prevent the vehicle from retreating on an uphill road without causing the driver to feel uncomfortable.

  In the vehicle control apparatus according to the second invention, in addition to the configuration of the first invention, the prediction means further includes means for predicting the position of the uphill road where the vehicle stops. The control device further includes detection means for detecting a road surface gradient at the predicted position of the uphill road.

  According to the second invention, since the road surface gradient at the stop position of the vehicle predicted by the prediction means is detected, the engine speed is set before the vehicle stops so that the creep force corresponding to the road surface gradient can be generated. Can be raised.

  In the vehicle control apparatus according to the third aspect of the invention, in addition to the configuration of the second aspect of the invention, the detection means includes means for detecting a road surface gradient based on information from the navigation device.

  According to the third invention, the road surface gradient of the uphill road at the position where the vehicle is predicted to stop can be detected based on information from the navigation system.

  According to a fourth aspect of the present invention, there is provided a vehicle control apparatus, in addition to the configuration of any one of the first to third aspects, means for acquiring information related to the state of an accelerator pedal operated by a vehicle driver, Means for obtaining information on the state of the brake pedal operated by the driver, and means for detecting the speed of the vehicle. The prediction means includes means for predicting the position of the uphill road where the vehicle stops based on the speed of the vehicle when the accelerator pedal is not depressed and the brake pedal is depressed.

  According to the fourth aspect of the invention, when the brake pedal is depressed while the accelerator pedal is not depressed by the driver, the vehicle can be predicted to stop, and the vehicle speed and, for example, the time change (deceleration) Based on this, it is possible to predict a position where the vehicle speed becomes zero (the vehicle stops).

  In the vehicle control apparatus according to the fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the predicting means includes a position of the uphill road where the vehicle stops based on the speed of the vehicle and the time change rate of the speed. Means for predicting.

  According to the fifth aspect, the position at which the vehicle speed becomes zero (the vehicle stops) can be predicted based on the vehicle speed and the time change (deceleration).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, a block diagram of a vehicle control system including an engine ECU (Electronic Control Unit) 400 which is a control device according to an embodiment of the present invention will be described.

  As shown in FIG. 1, this vehicle is equipped with a power train including an engine 100 as a drive source, a torque converter 200, and an automatic transmission 300. Engine 100 controls the rotation speed of engine 100 by controlling the opening of a throttle valve that controls the amount of intake air based on a throttle rotation command signal from engine ECU 400.

  The torque converter 200 is a device that converts torque using hydraulic oil, and is also called a fluid coupling. It consists of three elements: a pump impeller on the input side, a turbine liner on the output side, and a reactor (stator) that amplifies torque. In the region where the turbine speed is low, the reactor is fixed and the torque is doubled. However, when the turbine speed approaches the pump speed, the reactor idles and acts as a simple fluid coupling.

  The automatic transmission 300 is, for example, a gear type stepped automatic transmission or a belt type continuously variable transmission.

  In such a power train, even when the driver takes his / her foot off the accelerator pedal and is in an idle state, the rotation of the engine 100 is transmitted to the automatic transmission 300 through the torque converter 200, and the vehicle starts to move slowly. Cause a phenomenon. Such a creep phenomenon varies depending on the number of revolutions of the engine 100. In other words, a creep force corresponding to the idle rotation speed of engine 100 is expressed, but if the rotation speed of engine 100 is maintained at a higher rotation speed than the idle rotation speed, a larger creep force can be expressed.

  Engine ECU 400 that is a control device according to the embodiment of the present invention controls the rotation speed of engine 100 so that when the vehicle stops on an uphill road, a creep force corresponding to the uphill road can be expressed. . Further, it is characterized in that the timing for controlling the rotational speed of engine 100 is performed from the time before the vehicle stops.

  As shown in FIG. 1, a vehicle speed signal, an accelerator pedal opening signal, and a brake signal are input to engine ECU 400. In addition, a navigation system 500 is mounted on the vehicle, and gradient information is input from the navigation system 500 to the engine ECU 400.

  With reference to FIG. 2, a map indicating the relationship between the slope of the uphill road and the idle up rotation speed stored in the memory of engine ECU 400 will be described.

  As shown in FIG. 2, a map is stored in the memory of engine ECU 400 such that the idling up speed decreases as the slope of the uphill road decreases, and the idling up speed increases as the slope of the uphill road increases. In other words, the greater the slope of the uphill road, the stronger the vehicle that stops at that position will receive a reverse force. Therefore, increasing the idle-up rotation speed and increasing the rotation speed during idling generates a large creep force. To prevent the vehicle from moving backward.

  With reference to FIG. 3, a control structure of a program executed by engine ECU 400 of FIG. 1 will be described.

  In step (hereinafter step is abbreviated as S) 100, engine ECU 400 detects that the vehicle is traveling on an uphill road with accelerator ON. In S110, it is determined whether or not the accelerator is turned off. Whether the accelerator in S100 is ON or that the accelerator in S110 is OFF is performed based on an access pedal opening signal input to engine ECU 400. Further, whether the accelerator in S100 is in the ON state or that the accelerator in S110 is in the OFF state may be performed based on a signal from an idle switch that changes from the OFF state to the ON state when the accelerator pedal is closed. . If the accelerator is in an OFF state (YES in S110), the process proceeds to S120. If not (NO in S110), the process returns to S110.

  In S120, engine ECU 400 determines whether or not the brake is on. This determination is made based on a brake signal input to engine ECU 400. If the brake is ON (YES in S120), the process proceeds to S130. If not (NO in S120), the process returns to S120.

  In S130, engine ECU 400 predicts the stop position of the vehicle on the uphill road. At this time, engine ECU 400 predicts the stop position of the vehicle based on the vehicle speed signal input to engine ECU 400 and the time rate of change (deceleration) of the vehicle speed signal obtained by differentiating the vehicle speed signal. In S140, engine ECU 400 obtains the uphill slope at the stop position predicted in S130 from navigation system 500.

  In S150, engine ECU 400 calculates the idle-up rotation speed from the uphill slope. At this time, the map shown in FIG. 2 is used.

  In S160, engine ECU 400 determines whether or not the engine speed has reached the target idle speed. The timing for idling up is set to the target rotational speed + α, and when the engine rotational speed of the vehicle is equal to or lower than (target engine rotational speed + constant α) (YES in S160), the process proceeds to S170. It is. If not (NO in S160), the process returns to S160. The constant α can also be indicated by a map or the like based on a reduction in engine rotation speed. An example of this map is shown in FIG.

  In S170, engine ECU 400 outputs a throttle opening degree command signal for realizing idling up for engine 100. Based on the throttle opening command signal, the engine speed is increased to the engine speed increased from the normal idle engine speed by the idle-up engine speed. In S180, engine ECU 400 detects the stop of the vehicle.

  An operation of engine ECU 400 serving as the vehicle control apparatus according to the present embodiment based on the above-described structure and flowchart will be described.

  The driver depresses the accelerator pedal and travels on the uphill road with the accelerator on (S100). At this time, when the driver finds the vehicle ahead of the host vehicle, the driver returns the accelerator pedal (YES in S110). Further, when the driver depresses the brake pedal (YES in S120), the stop position of the vehicle on the uphill road is predicted (S130).

  The uphill slope at the predicted stop position of the vehicle is acquired from the navigation system 500. The idle up rotation speed is calculated from the climb slope using the map shown in FIG. 2 (S150). If the engine speed of the vehicle ≦ (target engine speed + constant α) (YES in S160), the idle-up process is executed so as to increase the engine speed by the calculated idle-up speed ( S170). Thereafter, the vehicle stops (S180).

  This is shown using the timing chart shown in FIG. FIG. 4 shows changes over time in engine speed and vehicle speed. In the engine speed, a solid line indicates a state when executed by the engine ECU 400 according to the embodiment of the present invention, and a dotted line indicates a state when controlled by a conventional control device.

  As shown in FIG. 4, it is assumed that the accelerator pedal is turned off at time T (1) (YES at S110), and the brake is turned on at time T (2) (YES at S120). The engine speed and the vehicle speed gradually decrease with time from the time T (2) to the time T (3). When the engine speed of the vehicle becomes equal to or lower than the idle up start speed at time T (3) (YES in S160), an idle up process is executed, and at time T (3), the engine speed is greater than the idle speed. Also increases by the idle-up speed. Thereafter, the vehicle stops at time T (4).

  Conventionally, after the vehicle has stopped at time T (4), the rotational speed of engine 100 has been increased. On the other hand, in the present invention, at the time T (3) before the vehicle stops, the engine speed is increased by the amount corresponding to the idle increase than the idle speed. Therefore, after time T (4), the driver is not given an uncomfortable feeling that the rotational speed of engine 100 is increased while the vehicle is stopped. Conventionally, since the number of revolutions of engine 100 has increased in a state in which the vehicle has been presented after time T (4), the driver feels uncomfortable. In the present invention, the driver is not given an uncomfortable feeling due to the increase in the rotational speed of the engine 100 after the vehicle stops.

  As described above, according to the engine ECU that is the vehicle control device according to the present embodiment, when the vehicle is predicted to stop on the uphill road, before the stop, according to the road surface gradient of the uphill road. The engine speed is increased. Thus, the engine speed can be increased so that a creep force corresponding to the road gradient of the uphill road can be generated before the vehicle stops. For this reason, the idling speed is not increased so that the creep force according to the road surface gradient on the uphill road can be generated after the vehicle stops on the uphill road, and the driver does not feel uncomfortable. The engine speed can be increased before the vehicle stops. As a result, the vehicle can be prevented from retreating on the uphill road without giving the driver a sense of incongruity.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram including an engine ECU which is a vehicle control apparatus according to the present embodiment. It is a figure showing the map which shows the relationship of the gradient of an uphill road and idle-up rotation speed memorize | stored in engine ECU. It is a flowchart which shows the control structure of the program performed by engine ECU. It is a timing chart which shows a time change of engine speed and vehicle speed. It is a figure which shows the map showing the relationship between engine speed deceleration and the constant (alpha) used for idle up start determination.

Explanation of symbols

  100 engine, 200 torque converter, 300 automatic transmission, 400 engine ECU, 500 navigation system.

Claims (5)

A control device for a vehicle that travels driving force from an engine via an automatic transmission,
Predicting means for predicting that the vehicle stops on an uphill road;
When it is predicted that the vehicle will stop on the uphill road, the engine is controlled so that the engine speed is increased according to the road surface gradient of the uphill road before the vehicle stops on the uphill road. And a control means for the vehicle. The predicting means includes means for predicting the position of the uphill road where the vehicle stops,
The vehicle control device according to claim 1, wherein the control device further includes detection means for detecting a road surface gradient of the predicted uphill road position.   The vehicle control device according to claim 2, wherein the detection unit includes a unit for detecting the road surface gradient based on information from a navigation device. The control device includes:
Means for obtaining information relating to a state of an accelerator pedal operated by a driver of the vehicle;
Means for obtaining information relating to a state of a brake pedal operated by a driver of the vehicle;
Means for detecting the speed of the vehicle,
The predicting means includes means for predicting the position of the uphill road where the vehicle stops based on the speed of the vehicle when the accelerator pedal is not depressed and the brake pedal is depressed. The vehicle control device according to any one of claims 1 to 3. The vehicle control device according to claim 4, wherein the prediction unit includes a unit for predicting a position of an uphill road where the vehicle stops based on the speed of the vehicle and a time change rate of the speed. .

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