JPH04347344A - Driving speed controller of fork lift - Google Patents

Abstract

PURPOSE:To travel safely at a decreased vehicle speed within a pre-determined limited speed when a vehicle is run at night or inside a site, by fixing the highest value of target rotational speed to a specified value lower than no-load highest rotational speed of an engine in response to the driving condition of the vehicle. CONSTITUTION:Target rotational speed corresponding to a stepping-in quantity of the acceleration pedal 5 of an engine 1 is set, and a throttle moving distance for setting the real engine speed to the target rotational speed is calculated, and a means which moves the throttle based on the moving distance is provided. There is also provided a means which can fix the highest value of the target rotational speed to a specified value lower than the no-load highest rotational speed of the engine 1 in response to the driving condition of the vehicle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of the running speed of a forklift truck, and more particularly to a maximum speed control device for driving at night or within a premises.

0002

[Prior Art] Conventionally, it is necessary to limit the maximum speed of a forklift when driving within a premises or at night, but conventional methods include a method that warns with an alarm when the vehicle exceeds the maximum speed, There is a method in which the engine is automatically returned to idle speed when the speed is exceeded.

FIG. 6 shows an example of a system configuration of a conventional forklift traveling speed control device. In the figure, when an accelerator pedal 21 is depressed, a throttle wire 22 connected to the accelerator pedal 21 moves, which moves a throttle lever 23 to open and close a throttle valve 24 to control the rotational speed of an engine 20. The amount of depression of the accelerator pedal 21 is controlled by the throttle lever 23.
An actuator 25 is provided in the middle of the transmission, but the actuator 25 is normally in an OFF state.
As described above, the throttle valve 24 is opened and closed independently of the actuator 25 in response to depression of the accelerator pedal 21.

When the vehicle exceeds the speed limit, the actuator 25 is turned on when it is determined that the vehicle has reached the speed limit based on a signal from a vehicle speed sensor 27 that is input to an ECU (electronic control unit) 26. As a result, even if the accelerator pedal 21 is depressed, the throttle wire 22
will not operate, the throttle will remain closed, and the engine will return to idle speed. At this time, when the accelerator pedal 21 is released, the idle switch 28 is pushed by the accelerator pedal 21, the actuator 25 is turned off again by the signal from the ECU 26, and the opening/closing of the throttle valve 24 by the accelerator pedal 21 is resumed. .

[0005]

Among the above-mentioned methods, in the method of warning with an alarm, although the alarm sounds, the speed of the vehicle cannot actually be limited unless the driver takes measures to decelerate in response. In addition, with a method in which the engine speed automatically returns to idle speed, the engine speed suddenly drops, causing a shock, which can be dangerous, and is difficult to operate because it will not return to normal unless the accelerator is released.

[0006] In view of the above problems, in the present invention, without using the above-mentioned means, when a vehicle runs at night or within a yard, the speed of the vehicle is reduced to within a preset speed limit. The purpose is to provide a means for driving safely.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a vehicle in which the throttle opening of a carburetor is adjusted according to the amount of depression of the accelerator pedal of the engine. A means is provided for setting a corresponding target rotation speed, calculating a throttle movement amount for making the actual engine rotation speed match the target rotation speed, and moving the throttle based on the movement amount, so as to correspond to the running state of the vehicle. The present invention provides a traveling speed control device for a forklift, comprising means capable of fixing the maximum value of the target rotation speed to a predetermined value lower than the no-load maximum rotation speed of the engine.

[0008]

[Operation] When the engine accelerator pedal is depressed, the target rotation speed is set according to the accelerator opening degree, and on the other hand,
The actual engine speed of the engine is detected, and a throttle movement amount for making the actual engine speed match the target engine speed is calculated from the deviation value between the two engine speeds, and the throttle is moved based on this. This target rotational speed is fixed at a predetermined value whose maximum value is lower than the engine's maximum no-load rotational speed depending on the driving condition of the vehicle at that time. In this case, the traveling speed of the vehicle is limited by a means capable of limiting the maximum rotational speed of the engine to ensure safety.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings. FIG. 1 shows the system configuration of the first embodiment. As shown in the figure, an actuator 3 is attached to a carburetor 2 of an engine 1, and the actuator 3 opens and closes the throttle of the carburetor 2 in response to a signal from an ECU 7.

The amount of depression of the accelerator pedal 5 is detected by the accelerator sensor 5a and input to the ECU 7, and a target rotational speed is set in accordance with the amount of depression of the accelerator pedal 5. Here, the deviation between the actual engine rotation speed calculated from the input signal of the rotation sensor 4 and the target rotation speed is calculated, PID calculation etc. are performed so that the actual engine rotation speed becomes the target rotation speed, and the throttle opening is controlled. It will be done.

[0011] Here, when the limit switch 6 is OFF,
Depending on the depression of the accelerator pedal 5, the speed changes from idle to NMR (No Load Maximum Revo).
However, when the limit switch 6 is turned on, the NMR is limited, and no matter how much you press the accelerator pedal, the engine will not rise above the predetermined rotation speed, and the vehicle speed will not reach the predetermined speed. limited by speed.

FIG. 2 shows a flowchart of the engine speed control routine by the above system. To explain this flowchart below, in step 1, the accelerator opening is detected by the accelerator sensor 5a, in step 2, the ECU 7 sets a target rotation speed according to the accelerator opening, and in step 3, the limit switch 6 is turned on. If it is ON (Yes), it is determined in step 4 whether the target rotation speed is greater than the maximum rotation speed calculated from the gear ratio with respect to the current limit speed, and if it is (Yes). (If so) In step 5, the target rotational speed is lowered to be equal to the maximum rotational speed limit. Next, in step 6, the deviation value between the actual engine rotation speed and the target rotation speed is calculated, in step 7, the amount of throttle movement is calculated by PID calculation, and in step 8, the throttle valve is moved to reach the predetermined engine rotation speed. control as follows.

As described above, when driving in the premises or at night, the limit switch (Sw) 6 is set so that the maximum speed limit set in advance by the driver is set, and when driving in the premises or at night. When a driver turns on Sw 6 , the maximum speed can be automatically limited regardless of the amount of depression of the accelerator pedal by the driver, and the vehicle can be driven safely without any problems in operability. Also, when driving outside the premises, there is a limit Sw.
If 6 is turned off, maximum rotation up to NMR is possible, speed can be controlled freely, and work efficiency is improved.

Next, a second embodiment will be explained. In the first embodiment, the engine speed set by the limit Sw6 is fixed at a constant value, and therefore the speed limit of the vehicle is also fixed at a constant value, but in the second embodiment, The driver can change the speed limit depending on the surrounding situation while driving.

FIG. 3 shows a diagram of engine speed versus accelerator opening. In the case of the first embodiment, when Sw 6 is ON, the engine rotation speed is fixed to Rs, for example, but in the second embodiment, the range of this rotation speed is expanded and a variable resistor is used. For example, in FIG. 3, the set value of the engine rotation speed is set in several stages from R1 to Rm.

FIG. 4 shows a system configuration diagram of the second embodiment. The difference from the first embodiment in FIG. 1 is that volume 8 and A
Since the other parts are the same except that the /D converter 9 is added to the system, the same reference numerals are given and detailed explanations will be omitted. In this case, the switch 6 and the volume 8 are provided on the operation panel of the driver's cab, and the voltage from the volume 8 is used to convert the voltage from 0 to 255 through the A/D converter 9.
converted into stages (8 bits).

FIG. 5 shows an example of the maximum engine speed setting routine when the maximum value Rmax of the engine speed is set in 10 steps using the above system configuration.
Shown below. In FIG. 5, at step 0, a volume value VR (Volume R
ange, VR: 0 to 255) is input to the ECU 7. If VR ≦ 25 is YES in step 1, proceed to step 01 and the maximum engine speed is Rmax = R
It becomes 1. In step 2, 26≦VR≦50 is YE
If S, Rmax = R2 in step 02. The explanation of steps 3 to 7 is omitted below, and in step 8 17
If 6≦200 is YES, Rmax is set in step 08.
= R8, and in step 9 201≦VR≦2
25 is YES, in step 09 Rmax = R
9, and in step 9 201≦VR≦225
If NO, Rmax = R10 in step 10, and the maximum value Rmax of each engine speed is set. For example, in the case of a forklift engine, 1300 rpm to NMR (approximately 2950
rpm) range is divided into 10 equal parts. however,
The setting stage of this maximum value Rmax is not limited to 10 stages as shown in Fig. 5, but may be set at any stage.
: It is also possible to calculate the value directly from 0 to 255 as a variable.

According to the second embodiment, the maximum set value of the engine speed is made variable by adjusting the volume, so that the speed limit of the vehicle is made variable, so that the driver can easily adjust to the surrounding conditions inside the premises and when driving at night. It becomes possible to change the maximum speed limit in several stages according to the situation, and to control the driving speed in response to the actual situation, thereby enabling safe driving.

[0019]

[Effect of the invention] By implementing the present invention, the restriction Sw
By turning on or setting the volume value, the maximum speed of the vehicle can be automatically and reliably limited regardless of whether the accelerator is depressed, eliminating problems with driving when driving within a forklift yard or at night. , safety is ensured. Also, during general driving, this limit Sw
By turning OFF, the maximum speed is maintained up to NMR, and work efficiency can be improved depending on the situation.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart of an engine rotation speed control routine of the first embodiment.

[Fig. 3] Engine rotation speed of the first and second embodiments of the present invention -
It is an accelerator opening degree diagram.

FIG. 4 is a system configuration diagram of a second embodiment.

FIG. 5 is an example of a maximum engine rotational speed setting routine according to the second embodiment.

FIG. 6 is a diagram showing an example of a system configuration of a forklift traveling speed control device according to the prior art.

[Explanation of symbols]

1...Engine 2...Carburetor 3...Actuator 4...Rotation sensor 5...Accelerator pedal 5a...Accelerator sensor 6...Limit switch 7...ECU 8...Volume 9...A/D converter

Claims (1)

[Claims] Claim 1: In a vehicle in which the throttle opening of the carburetor is adjusted according to the amount of depression of the accelerator pedal of the engine, a target rotational speed corresponding to the amount of depression of the accelerator pedal is set, and the actual engine rotational speed is adjusted to the target rotational speed. The maximum value of the target rotation speed is set to the maximum no-load rotation speed of the engine in accordance with the driving condition of the vehicle. 1. A traveling speed control device for a forklift, comprising means capable of fixing the speed to a predetermined value lower than .