KR20230171498A - Methods for interlocking control of hydrostatic transmission and brake pedal for agricultural vehicle - Google Patents

Abstract

The control method according to the present invention allows the vehicle to decelerate quickly or slowly depending on the speed at which the brake pedal is pressed when the brake pedal is pressed in a hydrostatic transmission type vehicle. The control method according to the present invention can be applied to agricultural vehicles, construction machinery, industrial vehicles, etc.

Description

Method for interlocking control of hydrostatic transmission and brake pedal for agricultural vehicle {Methods for interlocking control of hydrostatic transmission and brake pedal for agricultural vehicle}

The present invention relates to a method for controlling the hydrostatic transmission and the brake pedal of a vehicle in conjunction with each other. More specifically, when the brake pedal is pressed in a vehicle with a hydrostatic transmission, the transmission control unit is activated in response to the speed at which the brake pedal is pressed. This is about an interlocking control method that causes vehicle deceleration to occur quickly or slowly.

The interlocking control method according to the present invention can be applied to agricultural vehicles, construction machinery, industrial vehicles, etc.

Typically, agricultural vehicles such as tractors are equipped with a transmission that determines the degree of power transmission according to forward, reverse, or driving speed in order to transmit the output of the engine to the driving wheels.

Agricultural work vehicles mainly use manual transmissions that have a simple structure and excellent fuel efficiency, but manual transmissions have the disadvantage of being difficult to operate and shifting shocks during shifting. Accordingly, in order to compensate for the shortcomings of the manual transmission, automatic transmissions, which can conveniently operate the driver and prevent the occurrence of shift shock, are being applied to agricultural vehicles.

Among automatic transmissions applied to agricultural vehicles, the hydrostatic transmission adjusts the discharge flow rate of the hydraulic pump by raising or lowering the swash plate angle of the hydraulic pump according to the angle of the forward or reverse pedal included in the user control panel, and rotates the hydraulic motor accordingly. As the speed changes, the speed of the agricultural vehicle changes.

Since the swash plate of the hydraulic pump is connected to the hydraulic piston, the swash plate moves simultaneously with the movement of the hydraulic piston, and the hydraulic piston is operated by the pressure of oil supplied into it. Additionally, the pressure of the oil supplied inside the hydraulic cylinder is controlled by the opening amount of the spool, and the movement of the spool is controlled by an electronic proportional pressure control valve.

The current output (current supply) to the proportional pressure control valve is mainly determined by the forward and reverse pedals, and the target current output according to the forward and reverse pedal angles is determined by a predetermined map as shown in FIG. 1.

The target current output and actual current output operate according to a certain time delay, which allows the agricultural vehicle to smoothly shift gears according to the user's forward and reverse pedal operations.

However, in agricultural vehicles, etc., the hydrostatic transmission operates independently of the brake pedal, so when the brake pedal is pressed while the hydrostatic transmission transmits engine power to the driving wheel, sudden start after stopping, engine ignition off, and too fast Problems such as braking time or braking time that is too slow may occur.

For example, as shown in Figure 2(a), if you press the brake pedal in a situation where the swash plate angle decreases by taking your foot off the forward or reverse pedal while driving, the vehicle stops, but when you take your foot off the brake pedal again, the swash plate angle decreases. If is not 0, it starts and stops again.

In addition, as shown in Figure 2(b), when the brake pedal is pressed in a situation where the swash plate angle decreases by taking the foot off the forward or reverse pedal while driving, the engine is turned off due to the load from the driving unit of the agricultural vehicle and the load from the brake. This can happen.

The present invention was proposed to solve the above problems, and when the brake pedal is pressed in a hydrostatic transmission type vehicle, the transmission control unit is linked to quickly or slowly decelerate the vehicle in response to the speed at which the brake pedal is pressed. The purpose is to provide a control method.

Another object of the present invention is to prevent the engine from turning off due to excessive load when the brake pedal is pressed while the vehicle is not stopped, so that the difference between the target engine speed and the actual engine speed is greater than a certain value and When the actual engine speed is lower than the maximum torque engine speed, it is recognized as a situation in which the engine is turned off, and the current is quickly reduced to reduce the load on the engine and provide an interlocking control method to prevent the engine from turning off.

Another object of the present invention is to provide an interlocking control method that can prevent safety accidents by allowing agricultural vehicles to respond quickly when the brake pedal is pressed in dangerous environmental conditions such as slopes.

In order to achieve the above object, a method of interlocking control of the brake pedal and the transmission according to a preferred embodiment of the present invention uses the position value information of the forward and reverse pedal sensors and the position value information of the brake pedal sensor to the transmission control unit. The swash plate angle of the hydrostatic transmission is controlled, and the rotational speed of the hydraulic motor 5 increases or decreases according to the swash plate angle, thereby increasing or decreasing the vehicle speed.

The swash angle is controlled according to the speed at which the brake pedal is pressed, which is transmitted from the brake pedal sensor, so that the vehicle decelerates quickly or slowly. When the speed at which the brake pedal is pressed is fast, the vehicle decelerates quickly, and when the speed at which the brake pedal is pressed is slow, the vehicle decelerates. This can be done slowly.

The transmission control unit obtains actual engine speed information, which may vary depending on vehicle speed, engine target speed, and load changes, and uses the position value information of the forward and reverse pedal sensors and the position value information of the brake pedal sensor together. Thus, the current output supplied to the proportional pressure control valve can be determined. The proportional pressure control valve can supply hydraulic pressure to the hydraulic cylinder in response to the current output to operate the swash plate.

When the brake pedal is pressed quickly, the transmission control unit may set the current output to 0 so that the vehicle does not start again when the vehicle stops and the brake pedal is released.

If the vehicle does not stop when the brake pedal is pressed, the current can be reduced depending on the speed at which the brake pedal is pressed. To explain this specifically, the speed of reducing the current is determined by removing noise or small vibration from the position value of the brake pedal sensor using a low-pass filter, differentiating it, and multiplying it by a predetermined gain. If you press the pedal quickly, the speed of current reduction may increase, and if you press the brake pedal slowly, the speed of current reduction may decrease.

To prevent engine shutdown due to excessive load on the engine while the vehicle is not stopped when the brake pedal is pressed, the difference between the target engine speed and the actual engine speed is greater than a certain value, and the actual engine speed is equal to the maximum torque. When the engine speed is lower than the engine speed, it is recognized as a situation where the engine is turned off, and the current is quickly reduced to reduce the load on the engine and prevent the engine from turning off.

The linked control method can be applied to hydrostatic automatic transmissions such as agricultural vehicles, construction machinery, and industrial vehicles. However, the application field of the interlocking control method is not limited to this.

The present invention has the following effects.

First, it provides an interlocking control method that allows the transmission control unit to quickly or slowly decelerate the vehicle in response to the speed at which the brake pedal is pressed when the brake pedal is pressed in a hydrostatic transmission type vehicle.

Second, in order to prevent the engine from turning off due to excessive load when the brake pedal is pressed while the vehicle is not stopped, the difference between the target engine speed and the actual engine speed is greater than a certain value, and the actual engine speed is the maximum. When the torque is less than the engine speed, it is recognized as a situation where the engine is turned off, and the current is quickly reduced to reduce the load on the engine and prevent the engine from turning off.

Third, after the vehicle stops by pressing the brake pedal, make sure that the vehicle does not suddenly start again when you release the brake pedal.

Fourth, agricultural vehicles can react quickly to prevent safety accidents when the brake pedal is pressed in dangerous environmental conditions such as slopes.

Fifth, it can be applied to various vehicles, such as agricultural vehicles, construction machinery, and industrial vehicles.

Figure 1 is a graph showing the current output of an existing hydrostatic transmission control unit according to forward and reverse pedal operations.
Figure 2(a) is a graph showing that when the existing hydrostatic transmission installed in an agricultural vehicle is driven, the vehicle stops by pressing the brake pedal, and then the vehicle starts and stops again when the brake pedal is released. (The 'position (%)' on the y-axis of this graph divides the incline angle of the pedal into 0~100%. When the pedal is fully depressed, it is 100%, and when the pedal is completely released, it is 0%. )
Figure 2(b) shows a situation in which the engine is turned off due to the load of the driving unit and the brake of the agricultural vehicle when the brake pedal is pressed in a situation where the swash plate angle is reduced by taking the foot off the forward and reverse pedals while the agricultural vehicle is driving. Graph showing.
Figure 3 is a configuration diagram showing linked control of the brake pedal and transmission of an agricultural vehicle according to a preferred embodiment of the present invention.
Figure 4 is a diagram showing power and signal flow according to linked control of the brake pedal and transmission of an agricultural vehicle.
Figure 5(a) is a flow chart showing a method of interlocking control of the brake pedal and transmission of an agricultural vehicle.
Figure 5(b) is a graph showing the relationship between engine speed and engine torque of an agricultural vehicle.
Figure 6 is a graph showing the results of interlocking control when the brake pedal is quickly pressed.
Figure 7 is a graph showing the results of interlocking control when the brake pedal is slowly depressed.
Figure 8 is a graph showing that engine start-off is prevented as a result of control using the interlocking control method according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms or words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor should appropriately use the concept of terms to explain his or her invention in the best way. It must be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle of definability. Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only embodiments of the present invention and do not represent the entire technical idea of the present invention, so various equivalents can be substituted for them at the time of filing the present application. It should be understood that there may be variations.

Linked control using the brake pedal of existing passenger vehicles was mainly performed with the engine control unit (ECU). Specifically, when the brake pedal is pressed or released, the engine control unit controls the engine speed or engine torque to prevent the engine from turning off.

However, for linked control of the engine control unit, the software and control algorithm that drive the engine control unit must be modified. However, in the case of agricultural/construction vehicles, it is rare for manufacturers to develop their own engines, so it requires a lot of cost and time to modify the software and control algorithm of the engine control unit.

Transmission control units (TCUs) are often developed directly in agricultural/construction vehicles, and modifying the software and control algorithm of the transmission control unit has the advantage of saving cost and time.

In addition, the brake pedal sensor applied to the agricultural vehicle in the present invention can obtain the position value in analog form, unlike the existing On/Off method, so that the operator of the agricultural vehicle can simultaneously check the position and speed at which the operator of the agricultural vehicle presses the brake pedal. This can prevent shock and engine failure.

Figure 3 is a configuration diagram showing the linked control of the brake pedal and transmission of an agricultural vehicle according to a preferred embodiment of the present invention, and Figure 4 shows the power and signal flow according to the linked control of the brake pedal and transmission of the agricultural vehicle. This is a drawing that shows.

The transmission control unit monitors the forward pedal position sensor, the reverse pedal position sensor, the brake pedal position sensor, the target engine speed (target engine speed), the actually measured engine speed (actual engine speed), and the vehicle speed sensor. Using the input data, determine the current output supplied to the electronic proportional pressure control valve (1).

The forward and reverse pedal position sensor detects the positions of the forward and reverse pedals (incline angles of the forward and reverse pedals) and transmits the signal to the transmission control unit.

Additionally, the brake pedal position sensor detects the position of the brake pedal (incline angle of the brake pedal) and transmits the signal to the transmission control unit. Preferably, the brake pedal position sensor is an analog sensor, and therefore, unlike the existing On/Off method, the brake pedal position sensor can obtain the position value in analog form, so that the position at which the worker of the agricultural vehicle steps on the brake pedal, You can check the speed at the same time, thereby preventing shock and engine failure.

The target engine speed means the engine speed (R.P.M.) predetermined by the position value of the engine throttle pedal or engine throttle lever.

In addition, the actual engine speed may vary depending on the vehicle speed, target engine speed, load change, etc., and refers to the actually measured engine speed (R.P.M.).

As shown in FIG. 4, the initial current output supplied from the transmission control unit to the proportional pressure control valve 1 is determined by the position value information of the forward/reverse pedal sensor and the position value information of the brake pedal sensor. Then, the output current is applied to the proportional pressure control valve 1 to determine the movement of the spool 2, and the pressure supplied to the hydraulic cylinder is determined by the movement of the spool 2.

The piston moves according to the pressure supplied to the hydraulic cylinder, and the swash plate of the hydraulic pump (3), which is directly connected to the piston, also operates at the same time. And, as the swash plate of the hydraulic pump 3 moves, the discharge flow rate of the hydraulic pump 3 increases or decreases, and the rotation speed of the hydraulic motor 5 also increases or decreases accordingly.

As the rotational speed of the hydraulic motor 5 increases or decreases, the rotational speed of the driving wheel through the gear increases or decreases, and the agricultural vehicle accelerates or decelerates. Additionally, as the agricultural vehicle accelerates or decelerates, the load applied to the engine changes.

After the initial current output, the transmission control unit acquires the vehicle speed, engine target speed, and actual engine speed information, which may vary depending on load changes, and obtains the position values of the forward and reverse pedal sensors and the position values of the brake pedal sensor. Together they can determine the current output. Here, the position values of the forward and reverse pedal sensors mean the inclination angles of the forward and reverse pedals, and the position values of the brake pedal sensor mean the incline angles of the brake pedal.

[Linked control method between brake pedal and transmission of agricultural vehicle]

FIG. 5(a) is a flow chart showing a method of interlocking control between the brake pedal and transmission of an agricultural vehicle, and FIG. 5(b) is a graph showing the relationship between engine rotation speed and engine torque of an agricultural vehicle.

The interlocked control method according to the present invention operates when the brake pedal is pressed while a current output (current supplied from the transmission control unit to the proportional pressure control valve) is applied by the forward or reverse pedal.

(i) As shown in Figures 5(a) and 6, when the speed of the vehicle becomes 0 by quickly pressing the brake pedal (in the case of No in S12), the current output is set to 0 (S13. That is, the swash plate angle = 0°) Make sure the vehicle does not suddenly start again when you release the brake pedal again. (For reference, the 'position (%)' of the y-axis in the graph of Figure 6 divides the inclination angle of the pedal into 0~100%, with 100% being when the pedal is fully depressed and 100% being when the pedal is completely released. Set to 0%.)

(ii) If the vehicle does not stop when the brake pedal is pressed (Yes in S12), the current is reduced according to the movement of the brake pedal. The amount of current to be reduced (current reduction speed) is determined by passing the signal value of the brake pedal sensor (S20) through a low-pass filter to remove noise or small vibrations (S21), differentiating it (S22), and then multiplying it by a specific gain (S23). ) can be decided (S24). In other words, if you press the brake pedal quickly, the amount of current reduction increases (the speed of current reduction is fast), and if you press the brake pedal slowly, the amount of current reduction decreases (the speed of current reduction becomes smaller). Since the value of the specific gain may vary depending on the unit in which the signal value of the brake pedal sensor is received, the difference may be large depending on the case. For example, the value of the specific gain may be -5 to 5, but since it may vary depending on the system and control logic, a value suitable for the system and control logic can be used.

When the brake pedal is pressed (S11) and the vehicle is not stopped (if S12 is Yes), excessive load may be placed on the engine and the engine may turn off. To prevent this, the difference between the target engine speed and the actual engine speed is greater than a certain value (if Yes in S14), and the actual engine speed is the maximum torque engine speed (the engine speed when the maximum torque is generated from the engine). ) (if Yes in S15), the load on the engine is recognized (defined) as a situation in which the engine is turned off and the current is quickly reduced (S16, that is, the swash plate angle of the pump is quickly reduced) to prevent the engine from turning off. You can reduce it to prevent the engine from turning off. Figure 7 shows this process. The current reduction rate (current reduction amount) in step S16 may also use the current reduction rate (current reduction amount) according to the calculation results of S20 to S24.

In S14, the 'constant value' may be approximately 200 to 500 R.P.M., but this range may vary depending on vehicle characteristics (e.g., tractor characteristics, etc.).

If the difference between the target engine speed and the actual engine speed in S14 is below a certain value, the pump swash plate angle may be reduced at a predetermined speed, for example, the current reduction speed (current reduction amount) according to the calculation results of S20 to S24. (S17).

In addition, if the actual engine speed is greater than the maximum torque engine speed in S15, the pump swash plate angle may be reduced at a predetermined speed, for example, the current reduction speed (current reduction amount) according to the calculation results of S20 to S24 (S17) .

Meanwhile, previously, if the brake pedal was pressed while the forward and reverse pedals were slowly released while driving and the swash plate angle was reduced, the load on the engine increased and the engine could be turned off. However, as shown in FIG. 8, in the present invention, it is possible to predict a situation in which the engine will be turned off while the brake pedal is pressed and quickly reduce the current output to prevent the situation in which the engine will be turned off.

1: Proportional pressure control valve 2: Spool
3: Hydraulic pump 5: Hydraulic motor

Claims (6)

Using the position value information of the forward and reverse pedal sensors and the position value information of the brake pedal sensor, the transmission control unit controls the swash plate angle of the hydrostatic transmission, and according to this swash plate angle, the rotation speed of the hydraulic motor increases or decreases to drive the vehicle. Speed increases or decreases,
The swash angle is controlled according to the speed at which the brake pedal is pressed, which is transmitted from the brake pedal sensor, so that the vehicle decelerates quickly or slowly. When the speed at which the brake pedal is pressed is fast, the vehicle decelerates quickly, and when the speed at which the brake pedal is pressed is slow, the vehicle decelerates. A method of interlocking control of the brake pedal and transmission, characterized in that this is performed slowly. According to paragraph 1,
The transmission control unit acquires information on the actual engine speed, which can vary depending on the vehicle speed, engine target speed, and load changes, and uses it along with the position value information of the forward and reverse pedal sensors and the position value information of the brake pedal sensor. Determine the current output supplied to the proportional pressure control valve,
A method of interlocking control of a brake pedal and a transmission, characterized in that the proportional pressure control valve supplies hydraulic pressure to the hydraulic cylinder in response to the current output to operate the swash plate. According to paragraph 2,
When the brake pedal is pressed quickly, the transmission control unit sets the current output to 0 so that the vehicle does not start again when the vehicle stops and the brake pedal is released, and the transmission control unit interlocks the brake pedal and the transmission. method. According to paragraph 2,
If the vehicle does not stop when the brake pedal is pressed, the current is reduced according to the speed at which the brake pedal is pressed,
The speed of reducing the current is determined by removing noise or small vibrations from the position value of the brake pedal sensor using a low-pass filter, differentiating it, and multiplying it by a predetermined gain. However, if the brake pedal is pressed quickly, the current decreases. A method of interlocking control of a brake pedal and a transmission, characterized in that the current reduction rate decreases as the speed increases and the brake pedal is slowly depressed. According to paragraph 2,
To prevent engine shutdown due to excessive load on the engine while the vehicle is not stopped when the brake pedal is pressed, the difference between the target engine speed and the actual engine speed is greater than a certain value, and the actual engine speed is equal to the maximum torque. A method of interlocking control between the brake pedal and the transmission, characterized in that when the engine speed is lower than the engine speed, it is recognized as a situation in which the engine is turned off, and the current is quickly reduced to reduce the load on the engine and prevent the engine from turning off. According to any one of claims 1 to 5,
A method of interlocking control of the brake pedal and transmission, characterized in that it is applied to a hydrostatic automatic transmission of an agricultural vehicle.