JP2005145346A - Speed limiting device of commercial car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed limiting device for a commercial car, establishing good acceleration up to a specified limit speed while the limit speed is not exceeded. <P>SOLUTION: The car speed signal from a car speed sensor is read (S1), and the car acceleration is computed from the change rate of the car speed (S2). When the car speed has become equal to or more than the specified speed threshold which is smaller than the limit speed (S3), judgement is made whether the car acceleration is equal to or more than the specified acceleration threshold (S4). If the car acceleration is equal to or more than the acceleration threshold, it is judged as an empty car having a small total weight, and the target car speed for empty car to suit cars in empty condition is set as the target car speed for use in the speed control (S5). If the car acceleration is below the acceleration threshold, it is judged as a loaded car having a large total weight, and the target car speed for empty car to suit cars in the loaded condition is set as the target car speed for use in the speed control (S6). Then, the fuel injection amount to the internal-combustion engine is increased or decreased in accordance with the difference between the actual car speed and the target car speed (S7). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technology for improving acceleration to a speed limit while preventing a predetermined speed limit from being exceeded in a speed limit device for a commercial vehicle such as a truck.

Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 2003-155942 (Patent Document 1) or Japanese Patent Application Laid-Open No. 2002-349912 (Patent Document 2), a speed limiting device that limits a vehicle speed to a predetermined speed limit has been known. is there. In the speed limit device, when the vehicle speed approaches the speed limit, the target speed used for vehicle speed control is temporarily reduced and then gradually limited in order to satisfy the speed overshoot amount and acceleration performance, which are legal requirements, at the same time. “Filter control” to return to speed is performed.
JP 2003-155942 A JP 2002-349212 A

  However, when speed limit control by filter control is applied to a commercial vehicle, the following problems occur. That is, a commercial vehicle such as a truck has a characteristic that the total weight of the vehicle greatly fluctuates due to the weight of the load. For this reason, if speed limit control is performed at a target vehicle speed suitable for an empty vehicle, the total weight of the vehicle in the loaded vehicle is large, so it takes some time to reach the limit speed, and the vehicle driver feels that acceleration is poor. There is a risk that. On the other hand, if the speed limit control is performed at a target vehicle speed suitable for the loaded vehicle, the total vehicle weight is small in the empty vehicle, and thus there is a possibility that the allowable speed overshoot amount may be greatly exceeded.

  Therefore, in view of the above-described conventional problems, the present invention switches the target vehicle speed according to an empty vehicle or a loaded vehicle so that the acceleration up to the limit speed is made good without exceeding the predetermined limit speed. Another object is to provide a speed limiter for commercial vehicles.

  For this reason, in the first aspect of the invention, the vehicle speed detecting means for detecting the vehicle speed, the load state determining means for determining whether the vehicle is empty or loaded, and the vehicle speed detected by the vehicle speed detecting means are predetermined. Target vehicle speed setting means for setting a target vehicle speed according to the determination result by the load state determination means when the speed becomes equal to or greater than a predetermined speed threshold value less than the speed limit, and to the internal combustion engine according to the vehicle speed and the target vehicle speed A speed limiting device for a commercial vehicle is configured including an injection amount increasing / decreasing means for increasing or decreasing the fuel injection amount.

According to a second aspect of the present invention, there is provided acceleration detection means for detecting vehicle acceleration, wherein the load state determination means is an empty vehicle when the vehicle acceleration detected by the acceleration detection means exceeds a predetermined acceleration threshold, It is characterized by determining that the vehicle is loaded at other times.
The invention according to claim 3 is characterized in that the acceleration detecting means calculates and detects vehicle acceleration from a rate of change of the vehicle speed detected by the vehicle speed detecting means.

According to a fourth aspect of the present invention, the target vehicle speed setting means sets a target vehicle speed with reference to a map in which a target vehicle speed corresponding to an empty vehicle or a loaded vehicle is set.
According to a fifth aspect of the present invention, the target vehicle speed setting means calculates and sets the target vehicle speed from the total vehicle weight and the vehicle speed in an empty or loaded state.

  According to the first aspect of the present invention, when the vehicle speed is equal to or higher than a predetermined speed threshold value smaller than the predetermined speed limit, it is determined whether the vehicle is an empty vehicle or a loaded vehicle, and the determination result (empty vehicle or loaded vehicle). ) Is set according to the target vehicle speed. Then, the fuel injection amount to the internal combustion engine is increased or decreased according to the vehicle speed and the target vehicle speed. For this reason, by appropriately setting the target vehicle speed according to the empty vehicle or the loaded vehicle, the target vehicle speed at the time of empty vehicle will gradually return to the speed limit after once decreasing, and the difference between the vehicle speed and the target vehicle speed is small Therefore, it is possible to satisfy the speed overshoot amount, which is a legal requirement, while ensuring acceleration performance. On the other hand, the target vehicle speed at the time of loading will return to the speed limit in a short time after being lowered, and the difference between the vehicle speed and the target vehicle speed is large. Acceleration performance near speed can be secured. Therefore, regardless of whether the vehicle is an empty vehicle or a loaded vehicle, acceleration up to the speed limit can be made favorable while not exceeding the predetermined speed limit.

According to the second aspect of the present invention, it is determined that the vehicle is empty when the vehicle acceleration is equal to or higher than a predetermined acceleration threshold value, and that the vehicle is loaded at other times. That is, it is possible to easily and accurately determine whether the vehicle is empty or loaded by using the vehicle characteristic that the acceleration is sharp when the total vehicle weight is small and the acceleration is slow when the total vehicle weight is large.
According to the invention of claim 3, the vehicle acceleration is obtained by calculation from the rate of change of the vehicle speed. For this reason, by utilizing a speed sensor that is indispensable for electronically controlling the internal combustion engine, vehicle acceleration can be obtained without adding a new sensor, and an increase in cost can be suppressed.

  According to the invention described in claim 4, the target vehicle speed is obtained with reference to a map in which the target vehicle speed corresponding to the empty vehicle or the loaded vehicle is set. For this reason, by setting the target vehicle speed obtained through experiments or the like in the map, tuning according to the output characteristics of the internal combustion engine can be easily performed. Further, since the target vehicle speed is set only by referring to the map, it is possible to prevent an increase in control load.

  According to the fifth aspect of the invention, the target vehicle speed is obtained by calculation from the total vehicle weight and the vehicle speed in an empty state or a loaded state. For this reason, tuning according to the output characteristics of the internal combustion engine can be easily performed by arbitrarily setting the arithmetic expression.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows the configuration of a speed limiting device constructed by applying the present invention to an internal combustion engine equipped with an electronic fuel injection device (hereinafter referred to as “fuel injection device”).
The speed limiting device includes a control device 10 incorporating a computer, a fuel injection device 14 that injects fuel into the internal combustion engine 12, and a vehicle speed sensor 16 as vehicle speed detection means that detects the vehicle speed. . The control device 10 realizes a load state determination unit, a target vehicle speed setting unit, and an acceleration detection unit, respectively, by a control program stored in a ROM (Read Only Memory), and performs fuel injection based on a vehicle speed signal from the vehicle speed sensor 16. A control signal is output to the device 14. Further, the control device 10 realizes an injection amount increasing / decreasing means by a control program in cooperation with the fuel injection device 14.

FIG. 2 shows the contents of the speed limit control that is repeatedly executed every predetermined time after the internal combustion engine 12 is started.
In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), a vehicle speed signal is read from the vehicle speed sensor 16.
In step 2, the vehicle acceleration indicating the rate of change of the vehicle speed is calculated from the vehicle speed signal. Note that the processing in step 2 corresponds to acceleration detection means.

In step 3, it is determined whether or not the vehicle speed is equal to or higher than a predetermined speed threshold. Here, the speed threshold is a value for determining whether or not the vehicle speed has approached a predetermined speed limit, and is set to a value that is 10 km / h smaller than the speed limit, for example. If the vehicle speed is equal to or higher than the speed threshold value, the process proceeds to step 4 (Yes), while if the vehicle speed is less than the speed threshold value, the process ends (No).
In step 4, it is determined whether or not the vehicle acceleration is equal to or greater than a predetermined acceleration threshold value. Here, the acceleration threshold is a value for determining whether the vehicle is an empty vehicle or a loaded vehicle. For example, according to the output characteristics of the internal combustion engine 12, the maximum acceleration when empty and the Set to approximately the middle value of the maximum acceleration. If the vehicle acceleration is greater than or equal to the acceleration threshold, the process proceeds to step 5 (Yes), while if the vehicle acceleration is less than the acceleration threshold, the process proceeds to step 6 (No). In addition, the process of step 4 corresponds to a load state determination means.

  In step 5, since the vehicle acceleration is equal to or higher than the acceleration threshold value, it is determined that the vehicle is empty, and an empty vehicle target vehicle speed suitable for an empty vehicle is set as the target vehicle speed. Here, the target vehicle speed for the empty vehicle is a value obtained by using the vehicle speed detected by the vehicle speed sensor 16 (hereinafter referred to as “actual vehicle speed”) as a parameter with reference to a map in which the target vehicle speed corresponding to the vehicle speed is set. Alternatively, a value obtained by a predetermined calculation from the total vehicle weight in the empty state and the actual vehicle speed can be used (hereinafter, the target vehicle speed for loading is also the same).

In step 6, since the vehicle acceleration is less than the acceleration threshold value, it is determined that the vehicle is loaded, and the target vehicle speed for loading suitable for the vehicle in the loaded state is set as the target vehicle speed.
In addition, a series of processes in step 3 to step 6 correspond to the target vehicle speed setting means.
In step 7, a control signal is output to the fuel injection device 14 in order to increase or decrease the fuel injection amount in accordance with the difference between the target vehicle speed and the actual vehicle speed. That is, if the target vehicle speed is greater than the actual vehicle speed (target vehicle speed> actual vehicle speed), a control signal for increasing the fuel injection amount according to the engine operating state is output, while if the target vehicle speed is smaller than the actual vehicle speed (target vehicle speed <actual vehicle speed). Speed), a control signal for reducing the fuel injection amount according to the engine operating state is output. It is desirable to dynamically increase or decrease the fuel injection amount according to the difference between the target vehicle speed and the actual vehicle speed. In addition, the process of step 7 corresponds to the injection amount increasing / decreasing means.

  In this way, as shown in FIG. 3, when the actual vehicle speed approaches the speed limit and reaches the speed threshold, it is determined whether the vehicle is empty or loaded in accordance with the vehicle acceleration at that time. That is, it is possible to easily and accurately determine whether the vehicle is empty or loaded by using the vehicle characteristic that acceleration is sharp when the total vehicle weight is small and acceleration is slow when the total vehicle weight is large. And the target vehicle speed used for vehicle speed control is variably set according to the empty vehicle or the loaded vehicle, and the fuel injection amount is increased or decreased according to the difference between this and the actual vehicle speed.

  For this reason, by appropriately setting the target vehicle speed according to the empty vehicle or the loaded vehicle, as shown in the figure, the target vehicle speed at the time of empty vehicle is gradually lowered to the speed threshold and then gradually returns to the speed limit. Since the difference between the target vehicle speed and the actual vehicle speed is small, it is possible to satisfy the speed overshoot amount, which is a legal requirement, while ensuring acceleration performance. On the other hand, the target vehicle speed at the time of loading is reduced to the speed threshold and then returns to the speed limit in a short time.There is a large difference between the target vehicle speed and the actual vehicle speed. Acceleration performance near the speed limit can be ensured while satisfying. Therefore, regardless of whether the vehicle is an empty vehicle or a loaded vehicle, acceleration up to the speed limit can be made favorable while not exceeding the predetermined speed limit.

  Whether the vehicle is an empty vehicle or a loaded vehicle may be determined, for example, by detecting the sprung weight based on a signal from a strain sensor attached to the axle and depending on the weight of the weight. When an air suspension that holds the vehicle height substantially constant is mounted, it may be determined whether the vehicle is an empty vehicle or a loaded vehicle from the air pressure supplied to the air spring. Further, instead of obtaining the vehicle acceleration by calculation from the vehicle speed, the acceleration may be detected directly from the acceleration sensor.

Configuration diagram of speed limiting device according to the present invention Flow chart showing the contents of speed limit control Explanatory drawing of the effect produced by the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control apparatus 12 Internal combustion engine 14 Fuel injection apparatus 16 Vehicle speed sensor

Claims (5)

Vehicle speed detection means for detecting the vehicle speed;
A load state determination means for determining whether the vehicle is an empty vehicle or a loaded vehicle;
Target vehicle speed setting means for setting a target vehicle speed according to a determination result by the load state determination means when the vehicle speed detected by the vehicle speed detection means is equal to or higher than a predetermined speed threshold value smaller than a predetermined limit speed;
Injection amount increasing / decreasing means for increasing or decreasing the fuel injection amount to the internal combustion engine according to the vehicle speed and the target vehicle speed;
A speed limiting device for a commercial vehicle characterized by comprising An acceleration detection means for detecting vehicle acceleration;
2. The load state determination unit according to claim 1, wherein the load state determination unit determines that the vehicle is empty when the vehicle acceleration detected by the acceleration detection unit is equal to or higher than a predetermined acceleration threshold, and determines that the vehicle is loaded at other times. Speed limiter for commercial vehicles.   3. The speed limiting device for a commercial vehicle according to claim 2, wherein the acceleration detecting means calculates and detects vehicle acceleration from a rate of change of the vehicle speed detected by the vehicle speed detecting means.   The said target vehicle speed setting means sets a target vehicle speed with reference to the map in which the target vehicle speed according to an empty vehicle or a loaded vehicle was set, The Claim 1 characterized by the above-mentioned. Speed limiter for commercial vehicles.   The commercial vehicle according to any one of claims 1 to 3, wherein the target vehicle speed setting means calculates and sets a target vehicle speed from a total vehicle weight and a vehicle speed in an empty state or a loaded state. Speed limiter.

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