KR20150039248A - Speed control structure of forklift by controlling engine rpm - Google Patents

Abstract

The present invention relates to a running speed control structure of a forklift by controlling an engine rpm. More specifically, the speed control structure of a forklift controls a running speed of the forklift through an engine control portion which controls the running speed of the forklift as controlling the engine rpm. The speed control structure of a forklift controls the engine rpm controlling to prevent a rapid acceleration of the forklift by controlling the amount of increase of the engine rpm when a current running speed is included within a preset control speed range of a speed limit by comparing the running speed of the forklift with the limit speed.

Description

TECHNICAL FIELD [0001] The present invention relates to a control system for a forklift,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control system for a running speed of a forklift by controlling an engine RPM, and more particularly, By controlling the increase amount of the engine RPM when the current running speed is within the predetermined control speed range of the limit speed by comparing the running speed of the current forklift with the limit speed, The present invention relates to a control system for a running speed of a forklift.

Generally, a forklift truck used for transporting heavy cargo in the industrial field is mainly used in a space such as a warehouse where cargo is loaded. The forklift typically travels with the cargo loaded to lift the cargo to a desired position or to carry the cargo within a predetermined area.

The forklift has a vertical mast extending in two stages in front of the vehicle. Two forks, which are engaged with the vertical mast, are formed. The fork is transported by pushing the fork under the cargo.

Therefore, since the ordinary forklift lifts the cargo through the fork arranged forward, a large load is applied to the front wheel of the car, and the front wheel is moved to the center of the front wheel so that the cargo placed in front of the car can be stably transported to a desired position. It is common to steer the rear wheels and drive the front wheels.

Since the forklift constructed as described above lifts the cargo by using only the fork disposed in front of the car so that the cargo can be easily lifted and lowered, it is possible to prevent the forklift in front of the car It is important to ensure the stability of the running so as to prevent the cargo from being damaged due to the dropping of the loaded cargo or the shaking during the speeding operation.

Therefore, in the conventional fastening vehicle, the warning lamp is blinked so that the driver can recognize that the vehicle is overspeed when the vehicle is overspeed, or a warning buzzer or the like is used to notify the user that the vehicle is overspeed, A warning device is placed.

However, since the overspeed warning device as described above is an indirect means that depends only on the judgment of the driver, it may happen that the driver does not recognize or ignore the overspeed warning device. Therefore, There is a problem that stability can not be ensured while driving because it can not be a fundamental countermeasure.

Therefore, recently, a forklift is provided with a speed control device for limiting the speed of the vehicle.

The conventional speed control device has a structure in which a stopper is provided at a lower portion of an accelerator pedal provided in a vehicle, and the stopper functions to stop the rotational motion of the accelerator pedal at a predetermined position. When the accelerator pedal is depressed, it limits the pedal from being stepped beyond the set position. Therefore, by restricting the movement of the accelerator pedal, the engine output is prevented from rising above the set output, so that the speed limit of the vehicle is restricted to not increase beyond the set speed.

However, the conventional speed control device as described above is not effective because it prevents the speed of the accelerator pedal from being increased by interfering with the rotation of the accelerator pedal by the stopper, and it is difficult to control the speed accurately. Further, since the speed increase is not limited until the speed increase is restricted by the stopper, there is a possibility that an accident may be caused by rapid acceleration of the vehicle.

The present invention has been made to solve the above problems,

In a speed control structure of a forklift, a running speed of a forklift is controlled through an engine control unit for controlling the running speed of the forklift by controlling an engine RPM, and the current running speed of the forklift is compared with a limiting speed, And more particularly to an engine speed control system for a forklift that controls an increase amount of the engine RPM so as to prevent rapid acceleration of the forklift.

According to an aspect of the present invention,

An engine RPM control structure of a forklift, comprising: an engine control unit for controlling a speed of an engine in response to an input of an accelerator pedal; A control unit connected to the engine control unit through CAN communication to control the engine control unit; And a speed sensor unit connected to the control unit and measuring the speed of the forklift. The control unit receives the engine RPM value from the engine control unit, receives the speed information from the speed sensor unit, Wherein the engine control unit calculates a limit RPM for controlling the engine RPM when the running speed is within a predetermined control speed range and transmits the limited RPM to the engine control unit when the limited RPM is received from the control unit, And the engine RPM is controlled according to the engine RPM.

In addition, the control unit may further increase the limit RPM when the running speed recognized from the speed information is within the predetermined control speed range, thereby controlling the amount of increase of the engine RPM to be reduced.

The control unit further receives the position of the accelerator pedal from the engine control unit and calculates the limited RPM so as to be proportional to the position of the accelerator pedal in the calculation of the limited RPM.

The control unit further receives the position of the accelerator pedal from the engine control unit and calculates the limited RPM so as to be in inverse proportion to the position of the accelerator pedal in the calculation of the limited RPM.

Further, the control speed range is characterized in that the running speed of the forklift is 90% to 95% of the limit speed.

In addition, the control unit may calculate the limited RPM by the formula: RPM = previous RPM - current RPM * (pedal position / proportional constant) * variable value,

In the calculation of the variable value, the variable value is calculated by a formula: variable value = ((current speed / limit speed - (limit speed - current speed) / 40) - 1).

The control unit may stop the engine RPM control by not calculating the limited RPM when the running speed recognized from the speed information is included in a range not less than a predetermined control speed range and a speed limit speed or less do.

The present invention having the above-

The speed of the forklift is controlled by controlling the speed of the forklift by controlling the speed of the forklift by controlling the speed of the forklift, The rapid increase of the engine RPM is controlled so that the rapid acceleration of the forklift can be prevented.

FIG. 1 is a block diagram briefly illustrating a speed control structure of a forklift according to a preferred embodiment of the present invention.
FIG. 2 is a flowchart illustrating a process of calculating a limited RPM by the controller constructed as described above.
3 is a graph showing the control speed range of the present invention as described above.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram briefly illustrating a speed control structure of a forklift according to a preferred embodiment of the present invention.

(Engine ECU) for controlling the speed of the engine of the forklift is connected to the control unit 10 via the internal communication network (CAN communication) of the forklift, And receives the limited RPM value from the controller 10 and controls the engine RPM in response to the limited RPM value.

As shown in FIG. 1, the present invention includes an engine control unit 20, a control unit 10, and a speed sensor unit 30.

The engine control unit 20 controls the running speed of the forklift by controlling the engine rotation speed of the forklift, that is, the engine RPM, and is connected to the control unit 10 and the accelerator pedal unit 40 for this purpose.

The accelerator pedal 40 (accelerator) is a known component for calculating an input value of an accelerator pedal disposed in a driver's seat and inputting the input value to the engine control unit 20 in order to accelerate the speed of the forklift. So that the driver can step on the foot. At this time, when the driver of the forklift presses the accelerator pedal to drive the forklift, an accelerator signal is generated and transmitted to the engine control unit 20. Generally, an accelerator signal having a higher voltage is generated as the accelerator pedal is depressed deeper So as to expect a speed increase proportional to the input of the accelerator pedal. Accordingly, the engine control unit 20 can recognize the input of the accelerator pedal (hereinafter, referred to as 'pedal position') through the accelerator signal received from the accelerator pedal unit 40, and transmits it to the control unit 10 do.

Meanwhile, the engine control unit 20 continuously and / or periodically transmits the engine RPM to the control unit 10, thereby providing information for the control unit 10 to monitor the engine RPM.

The speed sensor unit 30 is provided for measuring the traveling speed of the forklift truck, and may include any known speed sensor. The speed sensor unit 30 continuously and / or periodically measures the traveling speed of the forklift and transmits the measured speed to the controller 10. Therefore, the control unit 10 can store and monitor the traveling speed received from the speed sensor unit 30. Preferably, the speed sensor unit 30 may be configured to recognize the running speed of the vehicle by recognizing the rotation of the wheel or recognizing the rotation speed by one or more of the wheels of the forklift, The present invention is not limited thereto, and any known arrangement for measuring the traveling speed of the forklift can be included.

The control unit 10 is a component that is connected to the engine control unit 20 through CAN communication and controls the engine control unit 20. The control unit 10 includes a control unit 10, Of a microprocessor. For example, in the preferred embodiment of the present invention, the controller 10 may be an MC9S12C32VFU16 processor.

The control unit 10 receives the engine RPM value from the engine control unit 20 and receives the speed information from the speed sensor unit 30. When the running speed recognized from the speed information is within a predetermined control speed range The control RPM for controlling the engine RPM is calculated and transmitted to the engine control unit 20 so as to control the running speed of the forklift.

When the traveling speed recognized from the speed information is included in a range of a predetermined control speed range or more (greater than a predetermined control speed range) and a speed limit speed or less (less than the limit speed) The engine RPM control is stopped by not calculating the RPM.

FIG. 2 is a flowchart showing a process of calculating the limited RPM by the controller 10 constructed as described above.

As shown in the figure, the limit speed is first set by the driver (S001). The setting of the limit speed is set as the limit speed inputted from the input means (which may be constituted by any known input means) arranged in the driver's seat of the forklift is transmitted to the control portion 10. [

When the limit speed is set, the control unit 10 receives the speed information from the speed sensor unit 30, recognizes the current speed of the vehicle, and compares the current speed of the recognized forklift with the speed limit (S002).

In a preferred embodiment of the present invention, the control of the engine RPM for speed control is performed such that when the current speed is lower than the set speed limit and the current speed is close to the limit speed, that is, The amount of increase is adjusted. 3 is a graph showing the control speed range of the present invention as described above. Therefore, if it is determined in step S002 that the current speed is higher than the limited speed, the controller 10 performs control of the engine RPM as well as normal control.

In this case, the control unit 10 calculates the variable value first in the control of the engine RPM (S003) and calculates the limited RPM in proportion to the variable value (S004).

First, the variable value in the step (S003) is calculated by the following formula.

Variable value = (current speed / speed limit - 1)

The limiting speed in step S004 is calculated by the following formula.

Limit RPM = Current RPM - Current RPM * (Pedal Position / Proportional Constant) * Variable Value

The steps S003 and S004 may be performed in the same manner as the configuration for calculating the limited RPM for controlling the engine RPM.

On the other hand, if it is determined in step S002 that the current speed is lower than the limit speed, the controller 10 determines whether the current speed is within the control speed range (S005). In the preferred embodiment of the present invention, the control speed range may be a speed range of 90% to 95% of the limit speed as shown in FIG. 3, but is not limited thereto.

The reason for setting the control speed range is to prevent the vehicle from suddenly overspeeding if the engine RPM is largely changed at once by the input of the pedal position. In other words, if the driver significantly increases the RPM of the engine by greatly accelerating the accelerator pedal to accelerate the running speed of the forklift, the forklift is rapidly accelerated by the increase of the RPM of the engine and increases the risk of causing an accident . The control unit of the present invention is configured to prevent a rapid acceleration of the vehicle by setting a control speed range as described above in order to prevent this.

Therefore, the control speed range is set to, for example, 90% to 95% of the limit speed, and when the running speed of the vehicle is not within the control speed range, that is, 90% The engine RPM can be controlled to rise normally. However, if the running speed of the vehicle is included in the control speed range, that is, if it is included in the range of 90% to less than 95% In order to avoid exceeding the limit speed, control is performed so that the RPM is slightly increased.

As a result, even if the driver of the forklift presses the accelerator pedal largely to accelerate the running speed, the engine RPM close to the limit speed is slowly raised by the above-described structure, so that rapid acceleration can be prevented.

The above configuration is implemented by calculating the limiting RPM as follows.

First, if the current speed is not included in the control speed range in step S005, the controller 10 performs control of the engine RPM in the same manner as normal control.

In this case, the control unit 10 calculates the variable value first in the control of the engine RPM (S006) and calculates the limited RPM in proportion to the variable value (S008).

First, the variable value in step S006 is calculated by the following equation.

Variable value = (current speed / speed limit - 1)

The limiting speed in step S008 is calculated by the following formula.

Limit RPM = previous RPM - current RPM * (pedal position / proportional constant) * variable value

The step S006 may also be performed in the same manner as the configuration for calculating the limited RPM for controlling the engine RPM.

On the other hand, if it is determined in step S005 that the running speed of the current forklift is within the control speed range, the controller 10 sets the variable value to be higher than the normal control time, .

In this case, the control unit 10 calculates the variable value first in the control of the engine RPM (S007) and calculates the limited RPM in proportion to the variable value (S008).

First, the variable value in the step S007 is calculated by the following formula.

Variable value = (current speed / speed limit - (speed limit - current speed) / 40-1)

Therefore, the variable value is calculated to be a predetermined amount higher than that in the normal control.

The limiting speed in step S008 is calculated by the following formula.

Limit RPM = previous RPM - current RPM * (pedal position / proportional constant) * variable value

Therefore, when the current speed is within the control speed range, the limited RPM is controlled through the variable value calculated by a predetermined amount higher than that in the normal control. As a result, the engine RPM by the control unit 10 So that the control amount is adjusted.

Thereafter, the controller 10 transmits the calculated limited RPM to the engine controller 20 so that the engine RPM is controlled by the limited RPM (S009).

It will be apparent to those skilled in the art that, in the formulas described in the specification of the present invention, '40' or '1' described as a constant may be replaced by other constants if necessary

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the specific embodiments thereof, I do not want to. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10:
20: engine control unit
30: Speed sensor unit
40: Accelerator pedal section

Claims (7)

In an engine RPM control structure of a forklift,
An engine control unit for controlling the speed of the engine in response to the input of the accelerator pedal;
A control unit connected to the engine control unit through CAN communication to control the engine control unit; And
And a speed sensor unit connected to the control unit and measuring the speed of the forklift,
The control unit receives the engine RPM value from the engine control unit, receives the speed information from the speed sensor unit, and determines whether the running speed recognized from the speed information is within a predetermined control speed range. And transmits the limited RPM to the engine control unit,
Wherein the engine control unit controls the engine RPM in response to the limited RPM upon receiving the limited RPM from the control unit.
The method according to claim 1,
Wherein the control unit controls the engine RPM control unit to decrease the increase amount of the engine RPM by further increasing the limited RPM when the running speed recognized from the speed information is within the predetermined control speed range. Driving speed control structure.
The method according to claim 1,
Wherein,
Further receiving a position of an accelerator pedal from the engine control unit,
Wherein the limiting RPM is calculated so as to be proportional to the position of the accelerator pedal in the calculation of the limiting RPM.
The method according to claim 1,
Wherein,
Further receiving a position of an accelerator pedal from the engine control unit,
Wherein the limiting RPM is calculated so as to be in inverse proportion to the position of the accelerator pedal in the calculation of the limiting RPM.
The method according to claim 1,
The control speed range may be,
Wherein the running speed of the forklift is 90% to 95% of the speed limit.
The method according to claim 1,
In the calculation of the limited RPM,
Limit RPM = previous RPM - current RPM * (pedal position / proportional constant) * variable value
, The limit RPM is calculated,
In the calculation of the variable value,
Variable value = ((current speed / speed limit - (speed limit - current speed) / 40) - 1)
And a variable value is calculated according to the following formula: < EMI ID = 1.0 >
The method according to claim 1,
Wherein,
And the engine RPM control is stopped by not calculating the limited RPM when the running speed recognized from the speed information is included in the range of the predetermined control speed range and lower than the limit speed. Control Structure of Driving Speed of Forklift Trucks.

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